Copyright

Firstpublishedin2013byTheCrowoodPressLtdRamsburyMarlboroughWiltshireSN82HRwwwcrowoodcomThise-bookfirstpublishedin2013copyTheCrowoodPress2013AllrightsreservedNopartofthispublicationmaybereproducedortransmittedinanyformorbyanymeanselectronicormechanicalincludingphotocopyrecordingoranyinformationstorageandretrievalsystemwithoutpermissioninwritingfromthepublishersBritishLibraryCataloguing-in-PublicationDataAcataloguerecordforthisbookisavailablefromtheBritishLibraryISBN9781847976413

Contents

TitlePageCopyrightIntroduction

1BuyingYourFirstLathe2InstallingtheLatheandUsingItSafely3CuttingToolPrinciplesFeedsandSpeeds4SharpeningToolsandHoldingThemintheLathe5WorkholdingintheChuck6TurningbetweenCentresandFaceplateWork7ColletsandMandrels8TaperTurningandLatheAccessories9DrillingandReaming10BoringToolsandBoringHeads11KnurlingRadiusTurningandProductionMethods12TapsDiesandScrewcuttingAcknowledgementsandUsefulContactsIndex

AMyfordlathedatingfromthemid-twentiethcenturyassuppliedtoGamagesaLondondepartmentstore

Introduction

The lathe is often called the King ofmachine tools It is veryversatile and can be used to make all sorts of engineeringcomponentsHenryMaudslaywhomadehis first screwcuttingand metal-working lathe in England shortly before 1800 wasone of the first engineers to incorporate the slide rest aleadscrew and change gears into one machine This made itpossibletomakeinterchangeablescrewthreadswhichinturnrevolutionizedtheproductionofmachinesandmachinetoolsThis book is for you the practising or aspiring engineer

Whether you are working in an industrial environment or ahome workshop this book will help you to acquire importantnewskillsandgiveyouinsidertipsyouwonrsquotfindelsewherePerhapsyoudonrsquothaveaknowledgeablefriendtoteachyou

or you arenrsquot able to join a club It does not matter whatprevious experience you have this book will teach you thebasics of lathe work from first principles to advanced turningtechniques You will find all you need to know within thesepagesDuringmore than thirty years in the engineering industry I

haveworkedwithmanyengineersbothbeginnersandexpertsandhavetaughtmanyyoungpeopleduringtheirfirststepsintoengineeringWorkingasaself-employedengineerIlearntquickand accurate ways of working both frommy own experienceand from other engineers Since 2008 I have edited ModelEngineer and Model Engineersrsquo Workshop the two main UKmagazines formachining in the homeworkshop and this hasgiven me an insight into what amateur (and sometimesprofessional)engineersarelookingforIhavealsobeenabletoadvisemanyamateurengineersonhowtosolvetheirworkshopproblemsorjusttogetthemstartedontherightlines

ModelEngineersrsquoWorkshopintroducedin1990isarelativenewcomertothemodelengineeringsceneItdealsmainlywithtoolsandprocessesandisnowpublishedeveryfourweeks

ModelEngineerwhichcurrentlyappearseveryfortnighthasbeenpublishedcontinuouslysince1898Itismainlyaboutmakingprecisionmodelsbutoftenincludestechniquesforturninginthelathe

I would like to pass on some of this knowledge This bookMetal Turning on the Lathe is the first of three for CrowoodPressonaspectsofworkshopengineeringitwillbefollowedbyMilling and Introduction to Workshop Tools and TechniquesEachbookwillbeacomprehensiveguideforboththeamateurandprofessionalengineerAlatheisessentialtoallbutthemostbasicofworkshopsIt

enablesyoutoproduceturnedcomponentstoahighdegreeofaccuracywiththeminimumofeffort

ThebasicMyfordmodeltheML7wasmanufacturedformanyyearsTensofthousandsarestilltobefoundingaragesfactoriesandhomeworkshopsaroundtheworldThisistheprototypeML7LatheasrebuiltbyMyfordLtd

ThelaterML7RandSuper7modelswerefittedwithaclutchasstandardThissaveswearandtearontheelectricalcomponentsandthemotorTheyalsohadmorespeedsLaterversionsoftheSuper7canbefoundwithapowercrossfeedTheillustrationshowstheprototypeSuper7latheagainithasbeenrebuilttofactorystandardsbyMyfordLtd

TheAtoZofalathe(A)Changewheelguard(B)Countershaftpulleyguard(C)Drivebeltguard(D)Countershaft(E)Belttensionlever(F)

Oiler(G)Motor(H)Tumblergearoperatinglever(I)Headstock(J)Backgearoperatinglever(K)Mandrelnose(L)Left-handleadscrewbearing(M)Leadscrew(N)Halfnutoperatinglever(O)Toolclamp(P)Topslide(Q)Crossslide(R)Saddle(S)Apron(T)Carriagehandwheel(U)Screwthreadindicator(V)Lathebed(W)Rack(X)Tailstock(Y)Tailstockhandwheel(Z)Right-handleadscrewbearing

AnearlyMyfordlatheAlthoughverybasicitcandoalotofusefulworkintheworkshopespeciallyiftimeisspentonmakingafewsimpleaccessories

This book will show you how to use the lathe safely andeffectively in your workshop but first you should ensure thatyou are familiar with the main parts of the lathe and theirterminologywhichmaybefoundonpage9Chapter1ofthisbookisaboutchoosingalathewhatsizeof

lathe to buy the different types available desirable featuresandwhetheryoushouldbuyneworsecond-handChapter 2 covers installing a lathe how to lubricate it and

maintain it in good condition and advice on general safety inyourworkshopwithparticularemphasisonhowtousea lathesafelyChapter3will lookatthematerials fromwhichcuttingtools

aremadeaswellastheirbasicshapeandgeometryThenwe

willlookatselectingsuitablespeedsandfeedsChapter 4 dealswith sharpening lathe tools andhow to set

themupinthelatheChapter 5 covers the different types of chucks how to use

themandsetworkupaccuratelyinthemChapter 6 teaches you basic turning between centres and

then introduces turning with the work mounted on the lathefaceplateChapter7isaboutholdingworkinacolletandhowyoucan

make and use several different types of mandrel forworkholdingChapter 8 explains how to turn a taper using the top slide

theuseoffixedandtravellingsteadiesandmakingaformtoolChapter9explainshowtousedrillsandreamersinthelathe

includinghowtoselectthecorrectspeedsandfeedsChapter 10 shows the different ways to bore holes in the

lathewiththeworkheldinachuckmountedonthefaceplateorheldonthecrossslideChapter 11 explains how to use knurling tools and radius

turning tools as well as making simple form tools and basicproductionmethodsChapter 12 shows you how to use taps and dies to cut

internalandexternal threads in the lathe Italsoexplainshowto set upa simplegear train and cut a screw threadwith thehelpofascrewcuttingdialindicator

1BuyingYourFirstLathe

WHATSIZEOFLATHEDOIREQUIRE

ThefirstthingtoconsiderwhenbuyingalatheisthesizeoftheworkthatyouwanttodoWhatisthelargestdiameteryouwillwanttoturnonitandwhatisthelongestlengthyouwillneedtoturnA3frac12times18in(90times457mm)lathewillallowamaximumdiameterof7in (178mm) tobe turnedover the lathebed thelatterfigureisknownastheswingInpracticethoughthisisatheoreticalmaximumas it is stillnecessary toholdandclampthe article being turned The swing over the cross slide isusuallymuchsmallertypically2in(50mm)Many lathes however aremanufacturedwith a gapbed at

the headstock end to enable short items of a large diametersuchaslocomotiveortractionenginewheelstobeturnedLathes are also sometimes available as standard and long

bed lathes The long bed lathe as the name suggests allowslongermaterial to be turned within the capacity of the latheWhen turning longermaterial the diameter will be limited bytheswingoverthecrossslideThiswillbealotsmallerthantheswingoverthebedIfbuildingamodelsuchasatractionengineoralocomotive

the deciding factor for the size of lathe is likely to be thediameterof the largestpairofwheels thatneed tobe turnedBefore deciding on the size of lathe required you shoulddetermine the size of the largest diameter and the longestlength of material that needs to be turned Another factor indeterminingwhat lathe tobuy is theavailabilityof sparesand

accessoriesisthecompanystilltradingwillitstillbetradinginthe future and are there large amounts of secondhand partsandaccessoriesavailablefromtooldealersoroneBay

Atypicalinvertertoconvert240voltssinglephaseto240volts3phase

LATHEELECTRICS

Single phase electric is where the lathe plugs into the mainssupplyinyourhouseThemotorwillhavetheusualliveneutraland earth leads Lathes supplied for factory use usually havethree phase motors and require three live wires each of adifferentphaseThinkofaphaseasan incomingwaveon theseashore three successive waves make up the three phasesneededEachphaseisthesameastheprecedingonebuttheyareoutofsyncandallpeakatadifferenttime

Aforwardreversecontrolboxforaninverter

Convertersandinverters

Youcan runsome3phasemotors fromasinglephasesupplyviaaconverteroraninverterThemotor informationplatewillusuallysay240volts440voltsif it iscapableofrunningonaninverter Inside the motor there will be changeover tags tochange the motor from 440V down to 240V Follow theconverterinverter manufacturerrsquos instructions for furtherinformation It isnotusuallyverycomplicatedto runa240V3phasemotor from an inverter and thiswill give a quieter andsmoother running motor than a single phase supply canprovide This usually requires some simple programmingexplainedintheinverterrsquosinstructionsanditusuallytakesfiveminutestogetthemotorworkingproperly

ThismotorispartoftheinverterpackageshowninthepreviousillustrationNowiringisinvolvedasthemotorleadplugsstraightintotheinverterbox

Theinverterrunsataconstantvoltagebutthespeedofthemotor will change as the frequency is raised or lowered Isuggest limitingyour inverter from full speed tohalf speed sothatthefanstillcoolsthemotorandstopsitfromoverheatingyoucanthenusethebeltstochangethemainspeedstepsasusual(Ifyoumustuseveryslowrunningitispossibletoaddaseparatefansuchasacomputercoolingfantogiveconstantairflow) Most inverter suppliers offer a forwardreverse andspeedcontrolboxthatcanbesetupinaconvenientpositiononthe machine These are well worth fitting for convenience inuse

Thisinverterisdesignedformountingonthefrontofthelathe

While inverters are designed to run only onemachine youcangetconverterstopowermorethanonemachineatatimeDependingonthesizeandpoweroutputconverterscostaboutthreetofourtimesasmuchasaninverterTherearetwomaintypesofconverterRotaryconvertersare

designedtorunmorethanonemotoratatimeThisis ideal ifyouwanttorunmorethanonemachineortwomotorsononemachineforexamplethemainmachinemotorandperhapsanauxiliary motor that drives the machinersquos coolant pump orpowerfeedsystem

Arotaryconvertercapableofpoweringmorethanone3phasemotor

ThesecondtypeisthestaticconverterwhichisdesignedtorunonemotoratatimeThereisofcoursenothingtostopyouusingthestaticconverteronmorethanonemachinebyfittingasuitablefemaleelectricalconnectortothestaticconverterandmatchingmaleconnectorstotheindividualmachinesThiswayyoucanconnectthestaticconvertertoonlyonemachineatatime

Thisstaticconverterissuitableforpoweringone3phasemotorIfyoufitasocketontheoutputhoweverdifferentindividualmachinescanbepluggedintoitoneatatime

Theelectricalloadingonrotaryorstaticconvertersmustnotexceed theirmaximumrating If indoubton the loadcapacityneeded to run your machine(s) you should consult the

manufacturerorsupplieroftheconverter

AnearthleakagetripisidealforquicklyeliminatingamotorwheretheelectricalinsulationisbreakingdownItisusefulfordetectingcertainelectricalearthingfaultsbutshouldnotbeusedasaguaranteeofelectricalsafety

Simpleelectricaltestingandsafety

Whenbuyingasmallsinglephasesecondhandlathetakewithyouanearth leakage testerof the typeused for lawnmowersandothergardentoolsIonceboughtaUnimat3lathetookithomeandpluggeditinItkeptblowingtheearthleakagetripinthefuseboxeventhoughithadworkedperfectlyatthesellerrsquoshouseIsolditonatalossbutthebuyerdidknowtherewasaproblemwiththeelectricsIt is most important that the metal parts of any lathe are

connectedtotheearthwirewhichisinturnconnectedtoearthMake sure that themotor frame is also connected toearthassome motors have dampening rubber mounts that insulatethem from themachine itself If in doubt about any aspect ofelectricalinstallationpleaseconsultaqualifiedelectrician

Acontinuousbedisidealwhenworkingwiththefaceplateorwithcollets

LATHEBED

Thelathebedisthebackboneoftheentirelatheandisthepartthat is mounted on the bench or stand There are two maintypesoflathebedtheplainbedandthegapbedTheplainbedisusuallycontinuousallthewayalongitslengthwhilethegapbedhasas itsnamesuggestsagap in thebedThis isnotaliteralgapbutasteppedsectionthatallowsbiggerdiameterstobeturnedthanyouwouldotherwisebeabletoturnonaplainbed latheThisgap isameansofmakinga lathesmaller thanwouldberequiredforaplainlatheabletoturnasimilarsizeof

componentSome continuous lathe beds have a section next to the

headstock that can be removed to increase the diameter thatcanbeturnedThisfeatureisusuallyonlyfittedtolargerlathessuchasaremostlyfoundinfactoriesSome lathes have hardened beds although most are just

plaincast ironTherearethreemaintypesofbedwayscalledshearstheplainflatbedwithsquarewaysabedwithaflattopand a 60 degree dovetail at each side and a bedwith raisedandinvertedVeewaysOnthelastofthesethetailstockusuallyrunsononesetofVeesand thecarriageonadifferent setofVees resulting in lesswear to themain slidesWidebedsarebetterandmoreaccurateasthelathecarriageislesslikelytotwistonawidebed

Close-upviewofatypicallathebedwithagapAgapbedlathehasalargerturningdiametercapacitythantheequivalentsizedcontinuousbedlathe

Someveryearly lathessuchas thosemadebyDrummondhad a round bed Although they worked well there is noadjustmentforwearinthelathebed

TheMyfordrangeoflatheshasasquareformofbed

ThistypeofbedhasaflattopwithaninvertedVeeateachsideTheVeesareusuallysetat60degreesbutcanvarywithdifferentmakers

The Unimat SL lathe was sold for many years and manysecondhandexamplesarestillavailableThismodeldiffersfrommostlathesinthatithastwosteelbarsasabedThisisnotaproblemhoweverastheUnimatisintendedonlyforverysmallandlightweightmodel-makingworkandthereistheadvantagethatthebedcanbereplacedbyfittingnewbarsWhen buying a secondhand lathe it is most important to

checktheconditionofthebedYouneedtomakesurethebedis reasonably free from dings rust and hacksaw marksHacksawmarksneartheheadstockareoftencausedbysawing

offworkwhile it isheld inthechuckdingsareusuallycausedbydroppingthechuckonthelathebedwhenscrewingitonoroffthemandrelAsimplechuckboardplacedonthebedwhilefittingorremovingthechuckwillprotectthebedItisalsoidealfor protecting the bed when filing or hacksawing work in thechuck

AlathebedwithraisedandinvertedVeesThecarriageusuallyslidesononesetofVeesandthetailstockslidesontheother

AmodernChineselathebedwithaninvertedraisedVeeThecarriageandtailstockusuallyslideonthesameVee

Wear ismost commonly found at the headstock end of thelathe as a result of machining many short components andrelatively few long ones Make sure the lathe carriage isproperlyadjustedattheheadstockandthenrunitalongasfaras you can towards the tailstock The carriage should bereasonablyfreebutnotlooseallthewayalongthebed

OldroundbedDrummondlathesarestillavailablesecondhandThisparticularexampleistreadledriven

AflatbedlathewithsquarebedwayssuchasaMyfordcanbe checked for wear on the lathe bed using amicrometer orvernierCheckovertheworkingpartofthelathebedonwhichthe carriage slides rather than the part that is not used forguidance Check both the width and the thickness of the bedwaysThetailstockshouldalsobeagoodslidingfitonanyguiding

surfaces Wear is most likely to be found on the tenon thatslidesbetween thebedwaysAworn tenoncouldprobablybereplacedbutthereisnotmuchyoucandoifthetenonguidesarewornTheonlyway to fixawornbed requiresacompletebedregrindThisislikelytobeexpensivesoitwouldbebettertolookforanunwornlatheDecentunwornlathesareouttheresincemanymodelengineersmayhaveboughtthemnewfortyorfiftyyearsagoandhardlyusedthem

TheUnimatSLisaverypopularsmalllatheItsbedconsistsoftwosteelbarsthatcanbereplacedveryeasilywithsilversteeliftheygetwornormorelikelywhentheygetrusty

Asimplewoodenchuckboardwillprotectthelathebedfromdingsandhacksawmarks

LATHEHEADSTOCK

Theheadstockisthelargecomponentmountedattheleft-handside of the lathe bed It needs to have good bearings An all-gearedheadwillalmostcertainlyhaveballorrollerraceswhilethe older type of lathe for amateurs may well have plainbearings either phosphor bronze or whitemetal These areperfectlyadequatebutyoushouldmakesurethere isnowearinthemSomelathesalsohaveamandrelthatrunsdirectly inbored holes in the cast iron headstock casting Plain bearingswillbeperfectlysatisfactoryas longasadequate lubrication isused

Close-upviewofaMyfordheadstockonanML7RNotethelargebronzebearingatthefrontTheearlierML7latheshadwhitemetalbearingsalthoughtheC7capstanhadbronzebearingsandahardenedlathespindle

Tocheck forwear in the lathersquosbearings fitachuck to themandrelandputadialtestindicatorontopofthechuckGentlytry levering the chuck up and down by using a steel bar orsimilarheldinthechuckYouarelookingforminimalmovementhereespeciallyonaheadstockfittedwithballraces

CheckingthelathebearingsforwearAnymovementupanddownindicateswearinthebearing

The mandrel is mounted in the headstock and is usuallythreaded to take a chuck or faceplate The lathersquos mandrelshould not move back and forth in the bearings If it doeshowever itwillprobablybepossibletoadjust ittocorrectanyendwise movement The mandrel should not be too stiff butshouldturneasilybyhandWhentestingalathemakesuretheheadstockbearingsare

correctlyadjustedsothatwherepossiblethereisnoplaySeta tool up take a trial cut alonga length of bar and check forchatter If you are using a correctly set tool and a suitablespeedchatterisasuresignofwornbearings

Manylatheshaveathree-orfour-stepdrivepulleyasthesecondstageofthedrivechain

POWERDRIVE

Manylatheshaveathree-orfour-steppulleyonthemandreltotake the drive from a similar pulley on the countershaft Thecountershaft is in turn driven from the motor which is oftenmounted at the back of the headstock and completes theintegral drive system that is so popular on most amateursrsquolathes

Thisparticularlathehasatwo-stepmotorpulleyandcountershaftwhichdoublestheavailablespeeds

SpeedchartonthebeltguardofaMyfordML7Rlathe

AfewlatheshaveaclutchfittedasstandardorasanoptionalextraTheclutchsaveshavingtostartandstopthemotorwhileitisrunningThishelpstostopwearandtearonthemotorandelectricalsystemAdifferenttypeofclutchsystemtheTriLevaspeedselector

wasonlyfittedtoMyfordML7orC7lathesThishasthreeleversfor setting threedifferent speedsDependingon the leveryoudepressyougetahighmediumorlowspeedIfyoupressoneof the levers downwhile another is right down the first leverwilldisengagethesecondsostoppingthemandrelfromgoinground If the lathe is switched off and all three handles aredepressed the mandrel is locked preventing rotation This isusefuliffilingorhacksawinginthelathe

TheclutchisnormallymountedinsidethelargecountershaftpulleyItisusuallyoperatedbyaleverattheright-handsideoftheheadstockattachedtoapushrodthatpassesrightthroughthecountershaft

TheMyfordTriLevaattachmentwillonlyfitML7andC7lathesandisnotsuitableforML7RorSuper7lathes

Therehasbeenatrend inrecentyearstodoawaywiththecountershaftandpulleysystemandtoreplacethemotorwithavariable speed one with an electronic controller This isacceptable except that at low revolutions it does not providethe torque that can be obtained from a countershaft systemThereisalsothedisadvantagethatthereisnowaytodrivethelatheifthecontrollercircuitboardfailswhereasyoucanjustfita new one if the belt breaks The board could of course befixed provided that a circuit diagram is available and theelectronic components can be identified Sometimes thecomponents are marked with internal house numbers ratherthan commercially recognized part numbers that can beorderedasareplacementfromacatalogueSomeboardsmighteven have the identification marks removed to make repairsalmostimpossible

ThethreadedendofalathemandrelisdesignedsothatthechuckbackplaterunstrueIfthechuckmountingfaceofthebackplateismachinedinsituthechuckshouldruntrueaswell

CHUCKMOUNTINGSYSTEMS

The threaded lathe mandrel nose is not by itself a suitablelocationforachuckorfaceplatesothenoseisusuallygivenaturned register on which to locate the chuck The chuck isscrewedrightontothemandrelovertheregisterandbuttsuptoaturnedcollartokeepthechuckrunningtrueTheothersideof the mandrel collar butts up against the main headstockbearingwhichusuallyactsasathrustfaceThemandrelisusuallyboredthroughandmachinedtotakea

MorsetapercentreforturningbetweencentresDonotputyourfingerineitherendofthemandreltocleanitwhilethelatheisrunningAneasywaytocleanthetaperintheheadstockiswithabottlebrush often sold in chemists to cleanbabiesrsquo bottlesAnalternativeisasoftfeltshotgunbrushdonotuseonemadefromwire

ThislathehasaplainregisterAccuracyreliesonthelathechuckbeingagoodfitontheregister

There are various systems of chuck mounting in useespeciallyon the larger lathesTheproblemwith thescrew-ontype with a register mentioned above is that the chuck orfaceplatecanunscrewwhenthelatheisrunninginreverseTheonly timeyoushould run this typeofmandrel in reverseveryslowly and without taking a cut is if you need to return thescrewcuttingtooltothestartofthethreadyouarecuttingAlternativespindlenosescanbeaplaindiscwitharegisterto

boltthechuckontooracamlockwherethechuckisheldontightlybyturningstudstolockthechuckontothemandrelTheplain discwith register relies on having chuckswith amatingregistertoworkproperly

AnAmericanstandardCamLockchuckmountingbackplateandCamLockchuckplatefittedtoachuckTheyareusuallyfittedtolargerindustriallathes

TheAmericanDstyleCamLocksystemeithertakesachuckor faceplate directly or it has a backplate that can have aregisterturnedonittosuittherequiredchuckAlthoughmanylathe mandrels with Cam Lock fittings have six holes thematchingchuckorfaceplateoftenhasonlythreelockingpinsThe advantage of both of the last two systems is that they

canberuninreversewithoutthechuckcomingoffthemandrel

Theleadscrewisdrivenfromthemandrelviaageartrain

SCREWCUTTINGGEARS

The left-hand end of the mandrel will often have a gearmountedonittodrivethechangewheelgearsandleadscrewThe mandrel gear usually drives a pair of gears called

tumblergearswhicharemountedona leveratthe leftoftheheadstock The direction of the leadscrew can be changed bybringingeitheroneortheotherintogearbyraisingorloweringaleverThereisusuallyacentralneutralpositionwhereneithergearisinmeshThissaveswearonthelathechangewheelsandleadscrew bearings as well as reducing noise while workingMandrelandtumblergearswillbediscussedfurtherinChapter12whenwesetupascrewcuttinggeartrain

A set of changewheels usually comprises about a dozengearsbutthiscanvarydependingonthemanufacturerThesechangewheels which take the drive from the tumbler gearsdown to the leadscrew are mounted on moveable studs toensurethegearsareinmeshwitheachotherDependingonthenumber of gears in the train the leadscrew will turn eitherclockwiseoranti-clockwiseThedirectionof the leadscrewcanbe reversed using the tumbler gears to enable right-hand orleft-handthreadstobecut

Oftentherearetumblergearsinthegeartrainthatcanreversethedirectionoftheleadscrew

YoucanusuallysetthegearstocutaveryfinepitchsothattheleadscrewactsasaselffeedwhenturningfromthesaddleIf you anticipate the need to do any screwcutting check thatthesuppliedscrewcuttinggearswilldotherangeofpitchesyourequire It has been known for certain lathes to be unable tohandle somecommonpitches a typical examplebeing26TPI(teeth per inch) A pitch of 26 TPI is often needed to repairmotorcycles and bikes made before the introduction ofmetrication

MakesurethatafullsetofchangegearsisincludedwiththelatheIfnottheyarereadilyavailablesecondhand

LEADSCREW

The leadscrew ismounted at the front of the lathe there areusuallybearings to support the leadscrewateitherendof thelathe bed It is used tomove the lathe saddle along the bedeither for a self acting feed or for screwcutting Some lathesalso have a graduated handwheel mounted at the right-handendoftheleadscrewforturningthemandrelbyhandSome of the larger lathes also have a separate feed shaft

whichisusuallyaplainroundshaftwithakeywaycutalongittodrivethesaddleusingafinefeedThissaveswearandtearontheleadscrewwhichisthenonlyusedforscrewcutting

Mostleadscrewscanhaveagraduatedhandwheelmountedontheright-handendoftheleadscrew

SCREWCUTTINGFACILITIES

Ausefulfeatureonanylatheistheabilitytocutscrewthreadsof different pitches Leadscrews come in different pitches acommon one being 8 TPI but many variations are fitted todifferent lathes including leadscrews with a metric pitch It isawkward tomachinemetricscrewswithan imperial leadscrewandviceversaSometimesmetricconversionsetsareavailablebuttheycanbehardtofindareusuallyexpensiveandrequirethe lathe to be changed over often using 127 tooth gearwheels This figure is derived from multiplying the metricequivalentof1in(254mm)byfivea127toothwheelisthusadirectconversiontoametricthreadonalathewithanimperialleadscrewA127 toothgear isusuallyvery large if itmatchesthepitchoftheremainingscrewcuttinggearsbutyoucouldusesmallergearswitha smallerDP (diametralpitch)but stillwith127 teeth Youwould also need amatching gear of say fiftyteethtogiveyoua2541ratio

Thislathehasbothaleadscrewforscrewcuttingandadriveshaftforthesaddleandcrossslidefeeds

Ascrewcuttingdialindicatorusuallymountedtotherightofthe carriage is a useful feature This is a small dial withdivisionsmarkedonitmountedonashaftTheotherendoftheshafthasagearthatmesheswiththeleadscrewandmakesthedial go roundWhen the clasp nuts are engaged the carriagemoves and as the gear moves at the same speed as thecarriagethedialstopsgoingroundWhen you engage the clasp nuts on the leadscrew the

positionwhereyouengagedependsonthepitchofthethreadbeing cut Some thread pitches allow you to engage at anydivision of the dial while others need to be engaged at aparticularpositionof thedialTheuseof thescrewcuttingdialindicator will be covered in Chapter 12 When using the finefeedyoucanengagetheclaspnutsatanymarkedpositiononthedialsoavoidingweartotheclaspnuts

AtypicalscrewthreaddialindicatorThisoneisengagedanddisengagedbylooseningtheboltandengagingthedrivegearwiththeleadscrew

LATHESADDLEANDAPRON

The saddle is thepart that slides on top of the lathebedandusually has the cross slide and top slide mounted on it Theapron ismounted to the frontof the saddleYoushouldmakesure there isnoplay in the saddle either sidewaysorupanddownandthatittravelsfreelyfromoneendofthelathebedtotheotherwithnotightspotsAtthefrontnearesttheoperatorthereisusuallyapairofclaspnuts(thesearesplitnuts)Thesecan be engaged or disengaged from the leadscrew forscrewcuttingormovingthesaddlealongwiththeleadscrewOncheaper lathes there is usually a solid nut that cannot bedisengaged

ThelathesaddleslidesalongthelathebedTheapronisboltedtothefrontofthesaddle

There is often a rack at the front of the lathe bed thatmatches upwith a handle and gears on the lathe apron Thiscan be used to move the carriage along the bed withoutwearingouttheleadscrewSomelatheshavethecarriagefeedwheel on the right but others have it on the left where hotswarfcanfallontoyourhandsThecheaperlatheshavenorackandrelyontheleadscrewtowindthecarriagebackandforth

ATee-slottedcrossslidemakesthesmalllathemoreversatile

CROSSSLIDE

On top of the carriage is the cross slidewhich canbewoundbackandforthacrossthelathebedWhenusingthecrossslideforfacingacrosstheworkthecarriageshouldbelockedtostopitmovingalongthebedLathesforamateurusearemorelikelytohaveaTee-slottedcrossslidewhilelargercommerciallathesare unlikely to have this facility The Tee-slotted cross slide isveryusefulespeciallyifyoudonrsquothaveamillingmachineYoucanboltworktothecrossslideformachiningusingacutterinthechuckorforboringworkpiecesthataretoolargetoswinginthechuckZero settingdials aredesirable for both the cross slide and

thetopslideTheyallowyoutosetthedialtozerowhichmakesiteasiertomeasuretheamountyouaretakingoffwithonecutInusewindthetooluptotheworkandtouchonsetthedialtozeroandwind the toolbackoff from theworkYounowknowwherezeroisonthetoolandcantaketherequireddepthofcut

withouthavingtoworkitout

Zerosettingdialsmaketurningandscrewcuttingtodepthveryeasy

Apairofzerosettingdialsreadytofit

LathescanbepurchasedwithimperialormetricfeedscrewsMostmodeldesignsareimperialbutmetricismakingheadwayandthismaywellbethewaytogoBewarelatheswithimperialfeedscrewsandmetricdialsTypically thesewillhavea funnynumber of handwheel divisions rather than a whole numberMostofthelathesyoumightcomeacrossareunlikelytohavea

power cross feed for facing This does notmatter as you caneasilywindthecrossslideacrossbyhandTheonlytimeIhavefound a power cross feed to be of use is when I had to faceacross a faceplate to true it up I have trued up similar sizefaceplatesbyhanditjusttookalittlelonger

Thetopslideismountedonthecrossslide

TOPSLIDE

ThetopslideismountedontopofthecrossslideThetopslideisnormallysetat90degreestothecrossslidealthoughitcanusually be swivelled around to various angles for turning ataperanangleorforscrewcuttingSomeofthecheaperlathesdonrsquothaveatopslideasstandardbutitisaveryusefulfeatureif you can get one The top slide should be able to rotateespecially for screwcutting but the top slide handlemay foulthecrossslideincertainpositionssocheckifthisisaproblemTheturningtoolisusuallymountedonthetopofthetopslideItcan either be clamped on directly usually with packing stripsunderneathorthetoolcanbemountedinatoolholdersuchasathree-orfour-waytoolpostoraquickchangetoolpostWewilllook at tool holding methods in Chapter 4 when discussingsettingupturningtools

TAILSTOCK

The component at the right-hand end of the lathe is thetailstock This usually has a handwheel to feed a drill into theworkbut leverfeedandcapstan-style feedingmechanismsarealso available You can lock the tailstock anywhere along thebed The tailstock has a barrel inside it that can bewound inandouttogivealinearmovementtodrillaholeinworkheldinthechuckThetailstockisusuallyboredtoaMorsetaperoftenof a similar size to the headstock so it can take accessoriessuchasdrillchucksmountedonaMorsetaperItcanalsotakeacentre for turningworkbetweencentres It is important thatboth the headstock and tailstock tapers are free frommarksscratchesandburrs

AlathetailstockwiththebarrelextendedNotethatitisnotusuallyaproblemifthechuckkeyisleftinthetailstockwhilenotinuse

Adjustment is usually provided between the base and themain body of the tailstock to allow for setting the tailstock inlinewith theheadstock Tailstocks canbe self ejectingwherethetool isextractedas it iswoundbackwhilesometailstockshavea throughholeandneeda tapwithabar to remove thetool Handwheel depth graduations for drill drilling to a

particularholedepthareveryusefulbutarenotoftenincludedon the cheaper lathes although industrial lathes usually havegraduatedtailstockhandwheelsThebettermakesoflathehavea lever clamping tailstock arrangement while the cheaperlathesoftenhaveaclampingspanneroranAllenscrewclamp

Allguardsshouldbefittedinplacebeforeoperatingthelathe

MACHINEGUARDS

Thedrivemotorcountershaft(iffitted)andpulleybeltsshouldallbeproperlyguarded It isveryeasy togetcaughtup inanunguardedmachineandtheconsequencescanbequitenastyThis has never happened to me but I have seen someonecaught up in a machine and it was not very nice I dorecommend that you make sure your machine guards arecorrectlyfitted

OTHERDESIRABLEFEATURES

Digitalreadoutsareusefulonalatheastheycanshowyouhowmuch to move the handwheels and how much material hasbeentakenoffTheyarequiteexpensivebutyoucan fit themyourself if youare carefulUnfortunatelymost of the cheaperversionsdislikesolubleoilorothercoolantifyougetitintothereadouthead

Adigitalreadoutsuitableformountingonalathe

Youwillneedtwoslidesoneforeachaxis

A soluble pump for cutting fluid is useful and often comesfittedasstandardonthelargerlathesHoweveratinofcuttingoilandabrushwillbegoodenoughformostworkandthatmaysuityoufine

Solubleoilpumpsandreservoirsarereadilyobtainable

Formostjobsyoucangetawaywithsomecuttingoilabowlandabrush

TheMyfordlsquoNortonrsquostylequickchangescrewcuttinggearbox

A Norton quickchange screwcutting gearbox saves time asyou donrsquot have to set up changewheel trains A gearboxhowever considerably increases the price of the averagesecondhand lathe A Myford Norton gearbox has twenty-fourpitchesandiscontrolledbytwoleversReversingtwogears inthe Myford changewheel train gives the gearbox twenty-fourfine feeds insteadof the twenty-fourscrewcuttingpitchesThegearboxhasa setofgearsarrangedasaconeBysliding thelever along and dropping themaster gear onto the cone youcanchangethegearboxratioandsothepitch

TheconegearsinsideatypicalNortonscrewcuttinggearbox(notanoriginalMyfordone)

SeveraldesignshavebeenpublishedtomakeyourownNortontypescrewcuttinggearboxThisoneisavailablefromHemingwayKits

SPINDLESPEEDS

Thespeed rangeneededona lathedependson thework it is

requiredtodoAgoodrangeofspindlespeedsisdesirablewithnoobviousgapsWithelectroniccontrolthisshouldnotbetoomuchofaproblemIdeally a back-geared lathe would be best but this means

either a good secondhand machine such as a Myford or aBoxford or alternatively one of the larger Asian-made latheswithanall-gearedheadstock

Thisbackgeararrangementisswitchedinandoutbyturningthetoggleonthepulleyandliftingaleveratthefrontofthelathe

Backgearnormallyconsistsoffourgearstwolargeonesandtwosmalloneswhichcanbeswitched inorout toreducethespeedofthelathebyaratioofusuallyabout51dependingonthe maker to enable you to turn large diameter workpiecesThis reduction is also essential on a screwcutting lathe asotherwisethemandrelwillbegoingtoofastwhilescrewcuttingandyouwonrsquotbeable tostop in the rightplaceat theendofthethreadIf buying a back-geared lathe check that both gearwheels

havealltheirteethItisamajorjobtostripdownalatheandfitnewgearwheelsassumingtheyareevenavailableassparesCheckthelatheinallgearrangeswiththelatherunningIfa

back-geared lathe or an all-geared head is noisy it could

indicatewearitwillalsobeanuisanceinyourworkshopasnoonewants to hear a noisymachine runningNoise could be amajorproblemespeciallyifyouhaveneighboursnearbyGearedheadsusuallyhaveawiderangeofspeedsthelarger

industrial lathescangoup tospeedsof2000rpmandsmallerversionsareoftenhigher

Anall-gearedheadonamodernindustrialsizelathe

On the more usual amateursrsquo lathe there is often acountershaft usually tensioned by a lever which tightens upthebeltreadyforuseThemiddlespeedofthecountershaft isusually chosen to be about one quarter of the motor speedMost small lathes have three speeds and the back geararrangement adds another three speeds giving six in all TheMyfordSuper7rangeoflatheshavefourspeedsandbackgearmaking eight speeds but there is also a double pulley on themotor countershaft section making sixteen speeds in allalthoughtheverylowestback-gearedspeedswillrarelyifeverbeusedSomeoftheolderColchesterChipmasterlatheshavewhatis

knownasaKoppVariatordriveThis isavariable speeddrivecontrolledbyadialandthesystemworkswellbuttheVariator

isveryhardtoreplaceifthedrivefails

ThissmallCowellslatheiscapableofdecentworkandatthetimeofwritingisprobablytheonlylathestillbeingmadeinBritain

MOUNTINGTHELATHE

There are three main options for mounting a lathe benchmounting portable or on a stand Ideally a makerrsquos standshouldbeusedformountingamediumto large latheandthestandisoftenanintegralpartof larger lathesAsmaller lathesuch as a Unimat or a Cowell can bemounted on a woodenchopping board or a similar small board These lathes can beputawayinacupboardafteruseThe alternative is a workbench but these are often made

from wood which can expand or contract depending on themoistureintheairWoodisnotagoodmaterialfromwhichtomakea stand for a larger latheas itwill attractmoisture andmayexpandshrinkordistortAmetalstandisabetteroptionWewilllookatinstallingthelatheinChapter2

AnArcEuroTradeC3screwcuttinglathemadebySiegThisisaverypopularentrylevellatheandmanyaccessoriesareavailable

Amedium-sizedscrewcuttinglathesuitableforgardenshedworkshops

SHOULDIBUYNEWORSECONDHAND

Beginnerssettingupaworkshopoftenaskifitisbettertobuyanew lathe or secondhand The preceding pages should have

given some guidance but there are more points to be takenintoconsideration

Alargerindustriallathewithafoot-operatedemergencycut-offswitchandbrake

BuyingNew

Thelistoflathesuppliersincludedatthebackofthisbookwereall in business at the time of writing Most will be willing todemonstratetheirrangeofmachinesattheirpremisesorwhileattendingmodelengineeringexhibitionsPaycloseattentiontomechanical noise the general paint finish and the workingslideway surfaceswhich should begroundDoes themachinehave sharpor roughedges (Handwheelsareespeciallypronetosharpedges)The main thing to consider though is the attitude of the

supplier Were they willing to talk to you and answer yourquestionseitheratanexhibitionoroverthephoneHowlongdo they take toanswer thephonewhenyou ring their servicedepartment Do they know the answer to a simple questionstraightawayordotheyhavetogetbacktoyouIsthemanual

written in English or Chinglish (translated awkwardly fromMandarinorCantonese)There are several suppliers of new lathes inmost countries

aroundtheworldbutthemajorityoflathesaremadeintheFarEastOftensupplierArsquosmachinescomefromthesamefactoryassupplierBrsquostheyarejustpaintedadifferentcolourandhavedifferentnamesandlabelsfittedAftersales service can vary greatly Usually companies that

havebeeninbusinesslongerwillofferbetteraftersalesservicebutotherpeoplersquosexperiencescanbefoundonInternetforumsoratlocalmodelengineeringclubsUsually theAsian lathesare reasonablywellmadebut they

often suffer from having plastic gears instead of metal onesOneortwocompaniessupplymetalgearsasstandardso it isworthaskingiftheirmachineshavemetalorplasticdrivegearsSome companies also offer after-market replacement metalgears

BuyingSecondhand

There aremany good quality secondhandmachines availablebut there is also a lot of worn-out rubbish If possible take aknowledgeable friend with you when purchasing a lathe Becareful when buying at online auctions such as eBay MostsellersaregenuinebutsomearenotNeverpartwiththecashuntil youhavechecked the latheover IhaveboughtoneBaywithoutproblemsbut Iamcarefulwhat IbuyandwhofromAsmall latheforacoupleofhundredpoundsisunlikelytobreakthe bank if it is a bit of a dog but a lathe that costs severalhundredpounds is adifferentmatter ThegreenMyfordML7RpicturedthroughoutthisbookwaspurchasedfromeBayItwasbrand new the motor had never been fitted and it was abargainwhencomparedwiththeretailpriceIdidpaycashoncollectionbutIwouldhavewalkedawayif ithadnotmatchedthedescriptioninanywayWhether purchasing new or secondhand check what

accessoriescomeaspartofthepackageandwhatwillneedto

bepurchasedseparatelyEssentialtoolingcanoftendoublethecost of a newmachine if it is not included in the price whilededicatedtoolingmaynotevenbeavailable forasecondhandbargainlathe

Youshouldnowhaveanideaofthesizeoflatheyouneedthefunctionofthedifferentpartsofthelatheandwhetheryouarebuying new or secondhand In Chapter 2 we will look atinstallingthelatheandsafetyintheworkshop

2InstallingtheLatheandUsingItSafely

If you are buying a new lathe completewith delivery to yourworkshopyoucangostraighttothesectiononsettingthelatheupIfyouarecollectingthelatheyourselfhoweveryoushouldpayattentiontoafewwordsonmovingit

Ifyouhaveroomtomanoeuvreanenginehoistcanbeusedtomovemachineryaroundsafely

MOVINGTHELATHE

MOVINGTHELATHE

When going to collect your lathemake sure someonewill betheretohelpyouloaditortakesomeonewithyouUnlessitisaminiaturelatheitwillbetooheavyforonepersontoliftHelpisalsoneededwhenyougetthelathehomeLiftingthelatheoutofacarcanbeharder than lifting it in It isadvisable tohavethreepeoplewhenunloading twoat theheavyheadstockendandoneliftingthelightertailstockendYoucanrentorbuyanenginehoist fora reasonablepriceand this canmakemovingthemachineeasierIf the machine is a substantial industrial type it would be

besttohireatransportcompanythatspecializes inmachineryremovals Professional machinery removers will usually haveproperlyequippedtransporttomoveheavymachinesThiswillprobablyworkoutcheaperthanattemptingtodoityourselfbutmake sure they have insurance in place in case they damagethelatheoryourpropertyYoushouldalsoensuretheyknowithas to beput in place as required in theworkshop youdonrsquotwanthalfatonofmachinerydumpedonyourdrivewithnowayofmovingitintopositionLathesareusuallytopheavywhenbeingmovedandcantip

overifyouarenotcarefulTheMyfordML7seriesforexampleoftenhasthemotorandcountershaftboltedtothebackofthelathe bed and this type of lathewill tend to tip backwards Asimple solution is to bolt two lengths of wood about 4 times 2in(100times50mm)tothelathefeetOneboltineachendwilldoifyou canrsquot drill holes in the correct position This will stop thelathe tipping backwards and also make it easier to lift IfpossibleyoushouldremovethetailstockThisisoftenaheavylumpofmetalbutitisusuallyveryeasytoslideitofftheendofthelathebedAnyotherlargeobjectsthatcanberemovedandreplacedlaterwillmakethelathelighterandeasiertomove

Twoplanksofwoodboltedtothelathefeetwilloftenturnanunmanageablemassofmetalintoaneasilyhandledmachine

Azerovoltsswitchisessentialequipmentonanymachinetool

Wearoldclotheswhenmovingyourlatheandhaveplentyofold rags to wipe off swarf and oil Lay down old blankets ordecoratorsrsquosheetsinsidethecarandasheetofthickcardboardMDForplywoodtohelpprotectthebootareawhenslidingthelatheintothecar

AsmallishlathecanoftenbefittedintoastandardhatchbackorestatecarYoumayfindhowever thatyouhavetodotwotrips one for the lathe and accessories and another for thecabinetthelathestandsonTosaveawastedjourneyIusuallytrytofitthelathecabinetinfirstIfIthenfindthatthecabinetdoesnrsquotfitIcanstillbringthelatheandtoolinghomeknowingthat Ihave tohireavan tocollect thecabinetbutalso that IhavenothadawastedjourneyIfyouhavetosplittheelectricsforexampletotakethelathe

offthecabinetdrawadiagramoftheelectricalconnectionssoyoucanrewirethelathewhenyougetithomeAdigitalcameraisalsoagoodmethodofrecordingthewiringconnectionsbutIwouldnotrelyonthecameraaloneIf the lathedoesnothaveazerovoltsswitch itwouldbea

good idea to fit one after you get the lathe home They areavailable quite cheaply andare easily fitted If in doubt aboutyourabilitytodoelectricalwiringconsultaqualifiedelectrician

Adjustablefeetareveryusefulforlevellingupthelathe

SETTINGUPTHELATHE

Somelathesusuallythelargerindustrialoneshaveanintegral

bedandcabinetThelathecanbesettotruewithjustshimmingunderthefeetorbyadjustingthefeetOther lathes may need to be mounted level and true to

ensureaccuracywhenturningSetthebenchstandas levelasyou can in both directions using a spirit level as a guide Anycheapspirit levelwilldoas longas it isaccurateYoucantesttheaccuracyofaspiritlevelbyturningitround180degreesifitisaccurateitshouldreadthesamebothwaysOnce the stand is reasonably level youcan level the lathe

ThisinvolvesjackingorshimmingupthelatheuntilitistrueinbothdirectionsIfusingawoodenbenchputmetalplatesunderthe feet tospread the loadShimoradjust the latheuntil it isreasonablylevel

Putthespiritlevelonthecabinetrsquoslongitudinalaxisandusetheadjustablefeettolevelthelathe

Insertalengthofbarinthechuckandputadialtestindicatoron top of the tailstock end of the bar Nip the headstock endmounting bolts down first and then tighten down the tailstockendboltsAdjustorshimthetailstockenduntilthereisnosignof movement on the test indicator Next 64repeat theprocedure with the dial test indicator on the front of the barAgainyouare looking fornomovementCheckbothdirectionsagainmakingsurethereisnomovementeitherhorizontallyorverticallywhenyoutightenthelathedownAdjustorshimuntil

there is no movement in either direction when the lathe isclampeddownAslongasthebedisnottwistedthelathebedshouldnowbetrue

1Insertapieceof⅛in(3mm)packingunderthespiritlevelatthetailstockendThiswillresultinarunonthedriptrayandalltheoldoilwillruntotheendofthelathemakingiteasiertocleanup

2Placethespiritlevelonthecabinetcrossaxisandusetheadjustablefeettolevelthelathe

3Putthespiritlevelonthelathecrossaxisattheheadstockendandlevelitasbestyoucan

4Putthespiritlevelonthelongitudinalaxisandlevelalongthelathe

5Testthetopofthebarthereshouldbenomovementwhenthelatheisclampeddown

6Testthefrontofthebaragainensuringthatthereisnomovementwhenthelatheisclampeddown

Alignthetailstockbyusingadialtestindicatorintheheadstock

AligningtheTailstock

NowweneedtosetthetailstockinlinewiththeheadstockDothisbyputting thedial test indicator into theheadstockchuckandtestthetailstockboreAdjustthetailstocktowardsthefrontortothebackofthebeduntilthetestindicatorreadstrueandtighten theclampscrewsA slightdifference inverticalheightwillnotbetheendoftheworlditjustmeansthereisprobablysomeweartothebaseofthetailstockcastingbutthereshouldbenovariationfromfronttobackinthehorizontalalignmentPutalongbarbetweenthecentresandtakealightcutalong

it using a fine power feed Run along the bar a couple moretimes at the same setting to remove any push offWhen youmeasure thebar it shouldmeasure the sameatbothends Ifthe bar is larger at the tailstock end you need to reduce theheightofthebedatthefrontofthetailstockslightlyIfsmalleratthetailstockendyouneedtoreducetheshimatthebackofthe tailstockend Itprobablywonrsquotneedmuchadjustmentasslightadjustmentstotheshimoradjustersatthetailstockendwillsoonbringitintoline

Usingatestbartocheckforparallelturning

LubricatingtheLathe

You should follow the manufacturerrsquos recommendations forlubrication Usually this is thin oil for the headstock oftenhydraulicoilandslidewayoil forthemovingpartsLubricationshouldbedoneregularlyIfthelatheisfittedwithasightfeedoileritshouldshowoilinitAdjustablesightfeedoilersasusedonMyfordandsimilarlathesshouldbeadjustedsothattheoildripswhen the lathe is running but does not dripmuchwhenthe lathe is stopped The slight vibration when the motor isrunningisusuallyenoughtocausetheoiltodripToomuchoilisbetterthannotenoughoilisfarcheaperthannewbearings

Atypicaldrip-feedlubricator

UseanoilgunonalltheoilnipplesYoucangetaroundthetendencyfortheoiltogoeverywhereexceptintothenipplebyputtingapieceofwritingpaperoverthenippleandthenusingthe oil gun as normal The paper will stop the oil squirtingeverywhereThemandrelbackgearalsoneedstobelubricatedWheninusethemainbackgearisrunningontheoutsideofthelathemandrelandneedstobelubricatedoftenoritwillgethotandwearChangewheels should be lubricated with oil not grease If

youusegreaseswarfwillsticktothechangewheelsandcauseunnecessarywearTo stopswarf running through themandrelanddroppingoutontothechangewheelsputawinebottlecorkor similar into the left-hand end of the mandrel This willeffectivelystopanyswarfgettingthroughtothechangewheelsOil the saddle and cross slide and also the nipples on the

tailstock Make sure oil is showing at the edge of the slidingsurfaces A squirt of oil on the cross slide and topslide feedscrew bearing is needed as well Check the manufacturerrsquosinstructions for lubricating the rest of the lathe Follow themotormakerrsquosrecommendationforlubricatingthemotorTrytoavoidusingWD40onthelatheWhileitisanexcellent

lubricantwaterdisplacerittendstodiscolourthelathebed

Useabitofpaperundertheoilguntostoptheoilsquirtingeverywhere

AvoidingtheRustFairy

Rust canplayhavocwith a lathe quickly turning thebedandother parts into a brownmess Various sizes of plastic coverssuitable forcovering lathesareoftensold foruseasbarbecuecoversinDIYstoresAplasticlathecoverwillhelptokeeprustatbaybutmoreneeds tobedoneAbagcontainingsilicagelplacedundertheplasticcoverforexamplewillabsorbexcessmoisturesilicagelcanbeboughtverycheaplyoneBay

SilicageliseasilyobtainablefromeBay

Alternatively you can buy a vapour phase inhibitor forprotecting the lathe The vapour phase inhibitor chemical issuppliedonafeltpadinsideaplasticpotThechemicalformsaprotectivelayeroneverysurfaceBecauseitisavapouritwillfind its way into every cranny and is also used for protectingtools and accessories in tool cabinets and drawers It usuallylasts for twelvemonths ifenclosedby theplasticcoverSomemachinetooldealersareabletosellsuppliesofthisproductinsmall ready to use containers rather than in industrialquantitiesAlwayscleanthelathedownafteruseswarfwillsoonrustif

leftonalatheasitwillprobablybecleanfromturningandwillnotbeprotectedbyoilTheuseofanovencookingtrayunderthe lathe bedmakes it easy to remove swarf at the end of aturning session The tray also helps to retrieve a parted offcomponentora lost screw froma tipped turning toolAnotheralternativeistocoverthelathechiptraywithnewspaperwhenyouhave finished turning remove thenewspaper screw it upandthrowitawayWhenfittingachuckorfaceplatetothelathemakesureyou

cleanthemandrelthreadtheregisterandthefaceYoushouldalso clean the mating threads the bore and the face on thechuckorfaceplateYoucancleanthethreadandboreeasilybyusing two toothbrushes bolted back to back with spacers inbetween Make sure the Morse tapers in the headstock andtailstock are cleanbefore fitting aMorse taper accessory TheMorse taper to be fitted should be free from scratches burrsandbruisesIt is good idea tomake a chuck board for usewhen fitting

chucks to a lathe or removing them This is a piece of wood(plywood will do) that sits on the lathe bed while you arescrewingthechuckonandoffThechuckboardwillprotectthelathe ifyoudrop thechuck It canalsobeused toprotect thelathebedwhenyouarehacksawingorfilinginthelatheIf you keep your lathe clean and lubricate it regularly it

shouldlastalifetime

AlargetraywillcatchmuchoftheswarfandtheholeslettheoildrainawayUsenewspapertosoakuptheexcessoil

SAFETYINTHEWORKSHOP

RememberyouareresponsibleforyourownsafetySafetyisamajorconcernintheworkshopTherearecertain

thingsyoushoulddoandobviouslythingsyoushouldnotByitsverynatureaworkshopcanbeadangerousplaceallwecandoismakeitassafeaspossiblewhilestillallowingustoworkinit

WorkingAlone

Mostofyoureadingthisbookwillprobablybeworkingaloneinasmallworkshopgarageorgardenshed IfyougethurtyoumaypossiblybeonyourownAsapriorityIsuggestyoutakeamobilephoneintotheworkshopandkeepitinyourpocketTheability to contact your family a friend or the emergencyservicesquicklycouldsaveyour lifeKeepthephoneswitchedoff while in the workshop however as it is an unnecessarydistraction

FirstAid

FirstAid

AFirstAidboxwithcontentsisanecessityandshouldincludeaneye-bathandeyewashYoushouldparticularlylearnhowtostopbloodflowingThereareplentyofwebsitesthatwilltellyouhowtodothisCheckthemoutnowbeforeyougobackintotheworkshop

ElectricalSafety

Checkforearthcontinuitywhilethemachineisunpluggedwithavoltohmmeterfromtheearthpinonthethreepinplugtothemetalpartofthelathe(somepaintmayhavetoberemovedforareadingtotakeplace)Youshouldgetareadingofzeroohmsorabeep if themeterhasacontinuity rangeYoushouldalsobe sure that the electrical sockets on the wall are correctlyearthedIfindoubtconsultacompetentelectricianLightingandelectricheatingshouldbeonaseparatecircuit

tothemachinessoyouwillstillhavelightifthemachinestripoutPlugasmalllightintothemachinecircuitsoyouhavesomelight if the lighting circuit trips out When I go on holiday Ialwaysturnoffthefusetripsforthelightinginordertomakeitmore difficult for intruders to move about quickly Leave thehouse alarm and smoke detectors on (The house alarmmayactivateeighthoursafter theelectricity is turnedoffwhenthebatteryexpires)

Adigitalmultimeterisveryusefulinthehomeworkshop

BeAware

Bementally alert while using the lathe Avoid operations thatmightputyourhandsatriskofenteringthemovingpartsofthelathe Do not operate any lathe while under the influence ofdrugs alcohol or prescription medication that may causedrowsinessorotherwiseaffectyourability to control the lathesafelyDonotattempttoworkonalatheandtalkatthesametimeIfyouhavetotalktosomeoneswitchoffthelathebeforedoingso

KeepItClean

TheareaaroundalatheshouldbekeptfreeofobstructionsThefloorshouldbecleananddrywithanyoilorotherspillscleanedup immediately The lathe should be kept clean and tidyMachinedangerareasshouldbemarkedontheworkshopfloorand observed Workbenches placed near a lathe should be

strongandequippedwithanon-slipsafetysurfacetostoptoolsor other items rolling onto the floor a rubber car mat willsufficeA rubberdoormat on the floorwill allow swarf todropthrough in order to save you getting swarf embedded in thesolesofyourshoes

Asuitablefloormatwillallowswarftodropthroughandhelpkeepyourfeetwarminwinter

LearntoUsetheLathe

Donotuseany lathebeforeyouare familiarwith thecontrolsandareawareofthedifferentwaysofstoppingitThismaybea clutch an onoff switch a No Volts release switch or anemergency stop button I strongly advise fitting a No VoltsreleaseswitchifyourlathedoesnothaveoneAswellasbeingusefulforstoppingthelatheinanemergencyitwillpreventthelathefromstartingupbyitselfafterapowercutIfyouarenotcomfortableworkingwith electrical equipment get a qualifiedelectriciantofittheswitchforyou

StaywiththeLathe

Nevereverwalkawayevenforamomentwhilethelatheyouare using is switched on Switch it off if you are leaving itunattended and only leave the lathe after it has come to a

completestopNeverleavealatheinanunsafeconditionMakesure that you have not left the chuck key in the chuck Thechancesarethatifyouarehalfwaythroughsettingupthelathewhen you return you will forget what you have or have notdoneIfindoubtleaveabignoticeremindingyourselftocheckthatthelatheissafebeforecontinuing

Donotleavethechuckkeyinthechuck

SwitchOffwhenAdjustingtheLathe

Shut off the power supply to the motor before starting anyoperationsrequiringaccesstothelathesuchaschangingtoolsmeasuring work mounting or removing accessories changingspeed and setting up change gears The lathemust be safelystopped Just zeroing a variable-speed drive is not safelystoppingitusethezerovoltsswitchtoswitchthepoweroffaswell

CheckbeforeStartingtheLathe

AlwaysrotateyourworkpiecebyhandtomakesureitclearsthetoolrestsaddleandbedDoublechecktomakesureyourworkis securely clamped in the chuck or between centres beforestartingthelatheBecertainthattheworkpieceturnsfreelyand

isfirmlymountedThespeedofthelathemustbecheckedbeforeturningiton

When turning irregular shapes start the lathe on a low speedandincreasethespeedbyapulleystepeachtimeIfthelatheisbouncingabout lowerthespeedandorbalancethework Ifthe work vibrates stop the lathe and check the reason ThechancesarethatyouarerunningthelathetoofastMeasuringequipment toolingandworkpiecesshouldnotbe

leftona latheastheycanvibrateoff intomovingcomponentsand be thrown around the room Check for loose items on alathebeforeuse

UsetheLatheGuards

NewlatheswillbefittedwithguardsoverthemotorshaftdrivebeltandspindlepulleysTheseguardsshouldalwaysbeinplacebefore using the lathe Any other moving parts should beguardedtopreventanythingfallingontothemovingpartsAlthoughguardsareoften removedbymachinistsprovided

they are constructed from clearmaterials and open and closeeasily theyaddsafetywithout interferingwith theworkbeingdone Guards will at the same time deflect swarf and anycoolantthatisbeingusedGuardsfittedtothelatheshouldnotbe removed while it is in use They should be made fromsuitablematerialandnothavesharpedgesTheyshouldnotberemovedforadjustmentandlubricationofthelatheunlessthisis unavoidable Lathemanufacturers donrsquot usually supply chipguards soaddingoneshouldbeconsideredChipguardswithmagnetic bases are available although they can attract steelswarftothemagnetPutthebaseintoaplasticbagtoaidswarfremoval

UseEyeProtection

Lathes can throw sharp metal chips considerable distancesespecially at high cutting speeds Apart from deep cuts thechipsmay leave the tool red hot cause skin burns and even

burnholes in clothing Youmust use safety goggles or propersafetyspectacleswhileintheworkshopAlwayswearindustrialqualitysafetyglassesfittedwithsideshieldsSpectacleswithoutsafety lenses are not adequate eye protection When theglasses get dirty do not wipe them off as they will becomescratchedWashthemoffunderthetapinstead

TakeCarewhenRemovingSwarf

Do not attempt to remove chips or turnings with your handsAlwaysswitchoff the lathefirstandeitherpull theswarfawaywithalargemetalhookorliftitoffusingapairofglovesIftheswarf is tangled around the lathe untangle it with a pair ofpliersandnotaglovedhandasitwillcutstraightthroughtheglovesandintoyourhandUseadustpanandbrushtoremovesmall chips and swarf from the swarf tray ndash never use yourhandsWhenswarfbecomesstringyandbuildsuponthetoolortoolpostturnoffthelathebeforeremovingit

AvoidLooseClothing

IfyouarenotwearingoverallswearshortsleevedshirtsorrolllongshirtsleevesabovetheelbowsLoosesleevescancatchonrotatingworkandquicklypullyourhandorarmintothe latheObviously though keep your arms protected if hot swarf isflyingaroundSwarf can get inside protective clothing especially collars

(useaclothespegtokeepyourcollartight)pocketsandshoesTostopthesleevesofanoverallcatchingsewelastic intothecuffsorwrapacoupleofthickelasticbandsaroundthecuffstostopthesleevesgettingcaughtupUnder no circumstances wear a necktie when operating a

latheProtectiveglovesshouldneverbewornwhileoperatingalathe Protective gloves may be worn when swarf is beingremovedbuttheymustberemovedbeforeswitchingthelathebackon

UseSturdyFootwear

WearsteeltoecapsafetybootstheyarenotexpensiveandwillhelptoprotectyourfeetfrominjuryifyoudropaheavyobjectonthemThelsquotrainerrsquoversionisparticularlycomfortableDonotallow stringy swarf to fall on the floor as youwill get cuts onyouranklesandmayeventripoverit

AvoidJewellery

Do not wear wristwatches rings or jewellery when in theworkshop as it could catch on a rotating part of the lathe orworkpieceThisalsoapplieswhenmovingalatheintooroutoftheworkshopsincetheycouldcatchona falling lathe IfyourotherhalfcomplainsthatyouhavetakenoffyourweddingringexplainthatyouwouldnrsquotbeabletowearitagainifyourfingerismissingduetoanaccidentLonghairshouldbetiedbackasyoucouldbepulledintothelatheifitgetscaughtintherotatingwork

LiftingintheWorkshop

Back injuries can be caused by incorrect lifting practices It isimportant to bend your legs when lifting rather than bendingyour back A hoist or engine lift should be used to lift heavyitems A stool in theworkshopwill take the pressure off yourlegs and will provide a welcome break after you have beenstoodatthelatheforawhile

Self-ignitingMaterials

If you machine titanium or magnesium which can ignite andburn vigorously keep the accumulation of turnings to aminimum If thematerialdoescatch firedonrsquotusewaterorawater-based coolant as an extinguisher since it will makematters much worse Before starting to machine titanium ormagnesiumfillalargebucketwithdrysandcoveritandkeep

it by the lathe The sand will smother the flames veryeffectivelyYoucouldalsobuyoneofthespecialfireretardantsusedinindustryBeware also of grinding aluminium on the bench grinder

Aluminium and steel filings are the ingredients of Thermite apowerful explosive that can also burn If you grind aluminiumandthenchangeovertogrindingsteeltheredhotsparksareliable to set the steelaluminium mix on fire This is a verydangerous combination ofmaterials and should be avoided atallcosts

SafetywithBarStock

Bar stock should be contained within the headstock and notallowed to protrude from the rear of themandrel I once sawsomeone switchona lathewhenabrassbarwas stickingoutfrom the back of the headstock by about two feet With thelathe running at 2000rpm the bar whichwas aboutfrac34in (19mm) in diameter was bent at right angles and caused theheavy lathe which weighed 1280kg to jump about Luckilysomeone managed to switch the lathe off before any majordamageoccurredItwasnottheoperatorhehadrunwellawayandwasnowheretobeseen

SomeFinalWordsonSafety

Wherever possible the machine height should be adjusted tosuittheuserWearestillusingfifty-year-oldmachinesbutfiftyyearsagothenationwasshorterTheworkplaceshouldbeprovidedwithuniformlightingthat

gives an adequate level of illumination Individual machinelightsarebestThe lathemust be set to operate at the speeds and feeds

recommended for thespecificmetalbeingturned If themetalrotatestooslowlyortooquicklyorthefeed istooslowortoofastaccidentsarelikelytooccurThe area directly in front of and behind the workpiece is

known as the lsquofiring zonersquo or the lsquored zonersquo This is where apiece of work is likely to go as it leaves the lathe Make it ahabit to keep clear of this zone when you turn the lathe onLearnwhere theNoVolts switch is as youmightneed to turnthelatheoffquicklyByfollowingalltheaboveadviceyoushouldnowbeableto

worksafelyfullyawareofanysafetyproblemsthatmightariseAtthispointyounowknowhowtoinstallthelathelookafter

itclean itandmaintain it InChapter3wewill lookatcuttingtoolsandexaminehowtoselectcuttingspeedsandfeeds

Thisbarisstickingouttoofarfromthebackofthelathe

3CuttingToolPrinciplesFeedsandSpeeds

The first part of this chapter will look at the materials fromwhichcuttingtoolsaremadeaswellastheirbasicshapeandgeometryWewill thenconsider selectingsuitablespeedsandfeeds

MAINTYPESOFTURNINGTOOLS

There are three main types of turning tool used in modernworkshops HSS (high speed steel) tools carbide brazed-ontoolsandinsertedtiptoolsAllhavetheirusesintheworkshopandformost jobsthere isnopreferenceforonetypeovertheothersTherearealsocarbonsteeltoolbitsalthoughinpracticetheyarejustaboutobsoleteCarbonsteeltoolscanbemadeinthe homeworkshop but apart frombeing used tomake formtools(seeChapter11)thereaderisunlikelytousethismaterialfortools

Ageneral-purposeHSSturningtoolsuitableformildsteel

HSSTOOLS

HSStoolscanbepurchasedsinglyorinsetsalreadygroundtothecorrectshapeIt ischeaperhowevertopurchasethemassquare tool blanks in various sizes ready for you to grind toshapeThecompleteready-groundsetswillprobablycomewithseveralshapesincludedthatyouwillneveruseIfyoucanbuyafewready-groundtoolscheaplytheywillbeofuseasguidestoseehowtosharpenyourownHSStoolblanksHSS form tools from industry are often available second-

handTheseareespeciallygroundtomachineacomplex formall in one go You can often find some that are ground to asuitable shape to form the end of a threaded componentincludingtheundercut

HSSformturningtools

Brazed-onCarbideTools

Brazed-on carbide-tipped tools are quite useful especially forfacing and boring cast iron but they really need a diamond-facedgrindingwheeltokeepthemsharpCarbidetipsandtoolscomeinvarioussizesandhardnesstosuitindividualmaterialscarbidetoolsforsteelwilloftenbepaintedbluethoseforcastiron are painted red and those for stainless steel are paintedyellowThecolourindicatesthesuitabilityofthetoolforcertainmaterials

Brazed-oncarbide-tippedtoolscomeinvariousgradesshapesandsizes

InsertedTipTools

InsertedcarbidetiptoolsareveryusefulbuttheyarenotcheapThe tipsarenotusually sharpenedafterwearingout you justthrow the tip away and fit a new one Most modern carbide

inserts however do have more than one cutting facesometimestheyhavetwoandoccasionallyfourormorecuttingedgesareavailableYoucanevengetformturningtoolswheretheinsertisroundandcanberotatedafull360degrees

Theleft-handtoolisblueindicatingitisformildsteelwhiletheright-handtoolisredindicatingitisforturningcastiron

Some diamond-shaped tips can be used in different toolholders two edges are used in one tool holder and the othertwoedgesareusedinanothertoolholdersoyougettwicethelifepertipInserted tip tools are available for internal and external

screwcuttingwherethetipsareheldat thecorrecthelixangleofthethreadinthetoolholderThedrawbackisthecostofthetipsandeachsizeofthreadusuallyneedsitsownsizeoftip

Aninsertedtipcarbideturningtool

Carbidegroovingtools

InsertedtipgroovingtoolsareidealformachininggroovesforOrings and circlips Theyare available inmany standardwidthsandcanoftenbeusedasparting-offtoolsforsmallerdiametersOneof themostusefulgrooving tools forsmallersizegroovesandpartingoffistheMiniThinsystemassoldbyMSCIndustrialSupplyCo

TheMiniThintoolholderisidealforgroovingandalsoforpartingoffsmalldiametersTheshankissostrongcomparedwiththecutbeingtakenthatusinganoverhangasshownisquite

safe

Coatingstoreducetoolwear

Tipsarealsoavailablewith various coatings that improve toollifeThemostcommoncoatingistitaniumnitride(TiN)whichisgold in colour Other coatings that offer slightly better wearresistancearetitaniumcarbonnitride(TiCN)whichisbluegreyincolourandtitaniumaluminiumnitride(TiAlN)whichisvioletbronzeReady-groundHSScuttingtoolssuchasdrillstapsandreamers are also available with these coatings but once yousharpenthecutterthecoatingisgoneTipped toolsneedadeeper cut ahigher feedandahigher

speed than HSS tools Thismeans that the lathe needs to bestrongrigidandhaveamplepowertodrivethe lathemandrelwhen taking a heavy cut this rules out using tipped tools onlathessmallerthanabout2in(50mm)centreheightSmaller tools are made to fit the Unimat and similar small

lathesbutthesemachinesjustdonrsquothavethepowerneededtodrivethemAtbesttakingacutwillstopthelatheatworstthetoolwillchip

Insertedtiptypes

Inserted tip tools come in many shapes and sizes Some tipshapes and sizes are made to an international standard andothers are to the makerrsquos own standards Wherever possibleuse ISOstandardtoolsas thetipswillbe interchangeablewiththosefromothermanufacturersandwillprobablybecheaperaswell The ANSI system commonly used in the USA is notcompatiblewiththeISOsystemusedintherestoftheworldIfyour lathe ispowerfulenoughyoucantakeadvantageof

insertedtippartingoffbladesThesearemounted inaspecialtoolblockandthebladecanbeslidinoroutdependingonthediameteryouarepartingoffThebladecarriesan inserted tipspecially designed for parting off There are three types of tipavailablesquare-endedtipstipsthatareangledtotheleftand

tips that are angled to the right Square tips are used forgeneral parting off tips angled to the left are usedwhen youdonrsquotwanttoleaveapiponthebackendoftheworkandtipsangledtotherightareusedwhenyouwantacleanfaceonthefrontoftheworkThe parting off blade is oftenmounted upside down at the

backofthe lathecrossslideTheactionofpartingofftendstolift the whole cross slide slightly and forces the cross slidetightly into thematching dovetail whichmakes itmuchmorerigidIfthepartingofftooldigsinwhileinthebacktoolpostthetool tends to lift and push away from the work whereas in afronttoolpostthetooltendstodiginandpullintothework

Simplifieddiagramofpartingofftoolangles(A)straightpartingtool(B)angledtotheleft(C)angledtotheright

POWERREQUIREMENTS

Whenturningmildsteelorstainlesssteelwithanycarbidetoolthe machine horse power required is considerably more thanthat required forordinaryHSStoolsThe twomain reasons forthisarethatcarbidetoolsoftenhaveanegativerakeangleonthecuttingedgeasthistypeofedgelastsmuchlongerthanapositiveangle especially for intermittent cuts andbecause in

industrial use carbide tips are called on to remove largerquantitiesofmetalathigherspeedsandfeedsFor guidance on using tipped tools in the small workshop

wheretimeisnotasimportantasinanindustrialenvironmentIwould recommendusing twice the speedused fornormalHSStools and a fine feed of about 0002in (005mm) per rev as astarting point This can be adjusted up or downdepending ontheresultsThemaindifferencebetweenHSStoolsandcarbidetippedtools(eitherbrazed-onorinsertedtip)isthehorsepowerrequirementofthemachineinuse

Thispartingofftoolismountedatthebackofthelatheinaspecialbacktoolholder

SELECTINGTHECORRECTSPEEDSFORDIFFERENTMATERIALS

Overmanyyears through trialanderror cuttingspeedshavebeendeterminedthatgiveanoptimumtoollifebalancedwithadecent surface finish These speeds are normally quoted inlsquosurfacespeedinfeetperminutersquoSpeeds and feeds used on industrial machines where the

primary tools will have inserted tips will be a lot higher than

thoseusedinthesmallworkshopwhereHSStoolsarethenormThe accompanying table gives an idea of the speeds that

shouldbeused forvariouscommon typesofmaterial likely tobefoundintheworkshopThespeedslistedshouldbesuitableforbothturninganddrillinginthelatheForreaminguseabout25percentoftherecommendedspeedsThe table is a guide only and it is likely that the machine

speedsavailablewillnotbeexactlythoserequiredandyoumayhavetoresorttolsquonearenoughisgoodenoughrsquoSetthelathetothe nearest speed lower than indicated in the table for thediameterandmaterialbeingcutThiswillbefineforHSStoolsDouble the recommended HSS speed for carbide tools For

parting off use about 30 per cent of the recommended HSSspeed For form tools use about 50 per cent of therecommended speed for the initial cuts and then engage thecorresponding back gear (just switch to back gear leaving thebelts on the same pulley) and gently tap the handle until itreachesthefinishedsizeandallowittofinishthecutbyitselfYou may have to adjust the speed down if you get a lot ofchatter

Forturningcastironuseacarbide-tippedtoolrunningattheHSSspeedtoremovetheskinYoucanthenfinishtheturningwithaHSSsteeltoolifyouwishPlease remember if doing any work that might be

unbalancedstartoffslowlyandincreasethespeedabeltstepatatime

THEACTIONOFCUTTINGTOOLS

Basicallya lathe tool isawedge that is forced into theendofthe rotating bar to remove metal As long as the tool is fedforwardwhilethelatheisrotatingmaterialwillberemovedA typical right-hand turning tool has a cutting angle of 90

degreeslessthesideclearancelessthesiderakeThecuttingangle for this example is 90ndash10ndash10= 70 degrees This is theangle that is wedged into the work to remove the materialSoftermaterialswillhaveasmallercuttinganglewhilehardermaterials will have a larger cutting angle Tool angles varydependingonthetypeofmetalbeingturnedToolsforturningsofter metals usually have higher rake angles than thosedesigned for harder metals since a turning tool will normallyholditsedgeforlongerinsoftermaterialsBrassalthoughsoftusuallyhasnotoprakeonthetoolatallOther angles to be aware of are the top rake and the side

rake

CUTTINGTOOLSHAPES

The followingaresomeof thedifferent shapes thatyoumightfindusefulforgeneralturningandmetalremoval

Right-handknifeturningtoolAllrakeanglesare10degrees

Right-hand knife tool This is used for general turning andfacingofbarstockDependingontheworkyouaredoingyoumayfindaleft-handversionofthistooluseful

Typicalroughingtool

Right-handroughingtoolIthasaleadingangleandasmallradius on the tip of the tool This tool is used for fast metalremovalwherefinishisnottooimportantAgainyoumayfindaleft-handversionusefulAroughingtoolcuttingatanangletoabarwillremoveachip

widerandthinnerthanatoolcuttingat90degreestothebarThis improves tool life although you will have to square theturningupwithastandardknifetool

Typicaldouble-sidedroughingtool

Double-sided roughing tool It can turn towards the left orright It canalsobeusedasaplunge tool to removematerialfroma groove orwhere the component needs to be lsquowaistedrsquodown

Simplepartingofftool

Simple parting off tool This is suitable formostmaterialsYouwillprobablyneedalargeoneforpartingofflargediameterbarsaswellasasmalloneforpartingoffsmallcomponents

Internal(top)andexternal(bottom)screwcuttingtools

ScrewcuttingtoolThisisusedforcuttingscrewthreadsTheanglewilldependonthethreadyouarecutting60degreesformetric55degreesforWhitworthandBSFetc

Shallowboringtoolcapableoffacingacrossthebottomofahole

Boring and facing tool This toolrsquos unusual shape will befound very useful when recessing a large bore It will plungestraight intoasmalldrilledholeandwillalso face rightacrossthebottomoftherecess

Double-endedchamfertoolchamferingadiameter

Double-ended chamfering tool It has 45 degree angles atbothendssoitcanbeusedtochamferexternaldiametersandinternalbores

Double-endedchamfertoolchamferingabore

Othershapescanbeusefulbutthetoolsshownhereshouldbesufficienttogetyougoing

BORINGTOOLS

Boring tools are used to clean up a previously drilled holepossiblytomakeitruntruebutmorelikelytoensuretheholeistothecorrectsizeTheyarenormallylongerthanordinarytoolsandtendtostickoutfurtherfromthetoolholderHSStoolsaresuitableformostusesCarbideinsertedtipboringbarsarealsoreadilyavailableandarethebestbetforturningcastironinthesmallworkshop

HSSboringbar

For really small holes down to2or3mm indiameter solidHSSandcarbideboringbarsarereadilyavailableAlthoughtheyarenotcheaptheywillbefoundveryusefulandquicktouseAnothermethodofboringahole is tousea longseriesslot

drillasaboringtoolInuseclamptheshankinthetoolholderwiththepointatcentreheightmakingsuretherestoftheslotdrillisclearofthesideoftheboreYoucanthenrunitthroughtheboreinasimilarmannertoastandardboringbar

Asmallcarbideboringbarinsertedintoamildsteelshank

PARTINGOFFTOOLS

PartingofftoolsprovideaquickwayofcuttingoffworkfromtheparentbarThereisrarelyanyneedtoworryaboutcuttingthecomponentofftothecorrectlengthtogetagoodfinishAslongasthecomponentislongerthanrequireditcanbeputbackintothe chuck or a collet and the parted off face can be faced tolengthorotherwiseworkedonThepartingofftoolcuttingfacecaneitherbesquareoritcan

beangledtotheleftorright(seepage43)Thesideofthepartingofftoolcouldevenberadiusedsothat

it forms a radius on the end of the next component orchamferedtoformalead-inedgeforthenexttool

CUTTINGLUBRICANTS

Tomake cutting tools cut easily and to prolong their life it issometimesbesttouseacuttinglubricantForsteelIpreferneatcuttingoilItlubricatesbutisnotidealforcoolingtheworkIn industry coolant is normally used This is oil that has an

additivetomakeitsolubleinwaterMostsolubleoilswilldobutthe synthetic ones tend to sting your hands if you have anyopen cuts I would not recommend using soluble oils on thehome workshop lathe as I think they tend to wash thelubricating oil off the slideways and can encourage rustHowever this ismypersonalpreferenceandmanypeopleusesolubleoilinthehomeworkshopwithoutanyproblemsOil is suitable for use when cutting steels mild steels

stainlesssteelsandhighcarbonsteelssuchassilversteelThebestlubricantwhencuttingaluminiumisparaffinItstops

thealuminiumfrombuildinguponthecuttingtoolBrassandcast ironarenormallycutdryWhenturningcast

ironona lathe if the latheisfittedwithasolubleoiltankthecastirondustwillhaveanaffinityforthesolubleoilIfthelatheisthenusedonaluminiumthefreecarboninthecast ironcancontaminatethealuminiumwithblackstreaks

Inormallyplacetheoilorparaffininasmalldish(actuallyacatordogfoodbowl)andapply itbyhandwithasmallbrushThisdoesallIneedThenextchapterlooksatgrindinglathetools

4SharpeningToolsandHoldingThemintheLathe

ThenexttaskistogrindasetofusefullathetoolsThe first thing you will need is an off-hand grinder The

grindercanbeadangerousmachineso itshouldbeusedwithcare Eye protection must be worn the guards should becorrectlyfittedandtheremustbeadequateilluminationIdonrsquotlike using a grinder in a small workshop as the grinding dustflies everywhere and canget onto themachine slideways andtools generally making the workshop dusty and dirty Ifpossible set up thegrinder in a separate areaaway from theworkshopIhavemygrindermountedonafoodchoppingboardso I can carry it outside to use This has the addedbenefit ofdaylight although you are dependent on the weather or youmightneedtouseitafterdark

Theguardofthisoff-handgrinderhasbeenwidenedtoacceptarecessedwheel

GRINDINGWHEELS

IthasalwaysbeenstatedthatyoushouldnevergrindatoolonthesideofthegrindingwheelSofollowingthistheorywewillbeusingarecessedwheelwhereitswidthismuchthickerthanthepartofthewheelusedtoclampthewheeltothegrinderIstruggledtofindarecessedwheelof6in(150mm)diameterandfinally found a 60 grit grinding wheel on a personal visit toAxminster Power Tools in Devon (I could find only an 80 gritwheel in theircatalogue)Thewheels I like touse forgrindingare A60K5V if I can get them and I prefer the white wheelsdesigned for the harder tool steels rather than the grey orbrown wheels which are more suitable for softer mild steelsThedesignationbreaksdown like thisA stands foraluminiumoxide 60 is the grit size K is the hardness (I J and K beingmediumhard)5 is thestructure(thespacebetweengrainsofgrit) and V is for vitrified the method of bonding the grainstogetherTheKandthe5canvaryabiteitherwayandthegrit

shouldbe4660or80with60beingpreferredThe80gritisabitfineandwillclogupquitequicklySo-called green grit wheels made from silicon carbide are

available for sharpening carbide tools They are usually softerthanaluminiumoxidewheelsinordertoallowthegrittobreakdownbeforethewheelbecomesglazedfromgrindingthemuchhardercarbide

Witharecessedwheelyoucancutontheouterfaceoftherecessedsideofthewheel

TestingtheWheel

The first thingyoushoulddowhenbuyingawheel is tomakesurethat it is ratedatasufficientlyhighspeedfor thegrinderon which it is to be used Off-hand grinders usually run ataround2900rpmsoyouwillneedawheelratedtoatleastthatspeed it is all the better if the grinding wheel is rated at ahigher speed than the grinder Care should be taken whenhandlinggrindingwheelsastheyarequitefragileifknockedordropped A grinding wheel should only be purchased from areputableengineeringsupplierSupportyourgrindingwheelona piece of wood and tap the wheel gently with a plasticscrewdriver handle or similar The wheel should lsquoringrsquo if itsoundsdullitshouldbebrokeninhalfandeitherthrownawayorusedontheworkbenchasasharpeningstoneNeverthrowawheelawaywithoutbreaking it into twoyouneverknowwho

mightgettheirhandsonit

Thistoolrestwasdesignedtosharpenplaneironsandchiselsbutitisfineforlathetools

Amoderndigitalanglegaugeisidealforsettingthetoolrest

MountingtheWheel

The wheelrsquos bore should be the same as the spindle of thegrindingwheelOften theborewillbe largerandyouwill then

need some plastic spacers to reduce it Spacers should bereadilyavailable fromyour localengineeringsupplierYoucanturn thespacers fromplastic if youcanrsquotbuyany ready-madeonesAt each side of the wheel you should fit a paper washer

thesearemadeofblottingpapertypematerialandwillprobablyhave been supplied already stuck on the wheel The grindershould have twometal flanges one to fit at each side of thewheel Both flanges should be the same diameter These willhold the wheel true and spread the tightening load on thewheelThegrinderwillhavetwodifferent threadsontheendsof its spindle The right-hand side of the grinder will have aright-hand thread and the left-hand side will have a left-handthreadThedifferentthreadsaretostoptheclampingnutsfromunscrewingwhenthegrinderisrunningTofitthewheelremovetheguardandundothenutRemove

the metal flange and then the wheel Make sure the flangesdonrsquothaveany remainsof theoldpaperwasheron themPutthenewwheelontothegrinderspindle(rememberthespacerthepaperwashersandtheflangesateitherside)andscrewthenuthand-tightFinallyholdthewheelgentlyandgivethenutapinchupwithaspannerYoudonrsquotneedtoover-tightenthenutjustsufficiently tostop thewheel fromcoming looseRefit theguard and spin thewheel by hand to ensure it is not rubbinganywhereNowwearealmost ready to switch thegrinder onBeforedoingsohoweverputonyoureyeprotectionandstandtoonesideofthegrindersoyouarenotinlinewiththewheelshould it burst Then switch the grinder on All should be fineandthewheelshouldberotatingsafely

TOOLREST

Theworkrestsuppliedwithanoff-handgrinderisusuallyjustabitofbentsheetmetalboltedonItisusablebutonlyjustI recently purchased a ready-made tool rest as a basis for

makinganimprovedgrindingrestThiswasoriginallydesigned

forsharpeningplanebladesandchiselsforwoodworkingbutitmakes an ideal rest for sharpening lathe tools It is made ofaluminiumandisfullyadjustableforangleThebestmethodofsetting the rest to the correct angle is to use a digital anglegauge These are now very cheap and are readily obtainableThepositionoftherestinrelationtothegrindingwheelcanbeadjusted on its sliding base Many designs for tool rests havebeenpublishedandyoucouldmakeoneofthoseinsteadifyouwishtosavemoneyThetoolclampassupplied isdesignedtoclampplane irons

andchiselssothisneedstobechangedLathetoolsneedtobepresented to the grinding wheel at the correct angles If youdonrsquot have a digital angle gauge this can be achieved usingsimpleguidesmadefromanglesheetmetalandsomescrewsIused gauge plate made from a high carbon steel with anaccurategroundfinishthatcanbehardenedandtemperedbutmild steel would be perfectly suitable if you donrsquot have anygaugeplateavailableYouwillfindaprotractorusefulyoucangetasteelonewith

an adjustable blade for a reasonable price The protractorwillbeusedtosetthetoolanglethatisgroundonthetools

Sheetmetalprotractorsareavailableverycheaply

LATHETOOLGEOMETRY

LathetoolsneedtobegroundtocertainanglesbuttheanglesdonrsquothavetobeexactFormosttoolssomewherehandywilldounless you are grinding a form tool to a particularly accurateshapeIthasbeennormalforbookstoshowtheanglesontoolsas used in a production environment where tools will ideallyhavealonglifeoftenthislifeiscalculatedaslastinganeight-hourshiftsothetoolonlyhastobesharpenedandresetonceadayInthehomeworkshopwecan increasethesecuttingangles

andgetbettercuttingattheslightexpenseofshortertoollifeWehavealreadyexplainedtheshapesof the tools thatyou

willfindmostusefulToolanglesareknownbytechnicaltermstop rake front rakeside rakeandback rakeThe rakeanglesvary depending on thematerial to bemachined but a set ofstandardtoolswillgetyoustartedSomeoftheaccompanyingphotographsareactuallyoflarge-scalewoodenmodels

Theleft-handtoolissuitableforbothfacingandturningtheright-handtoolissuitableforturningonly

Left-handsideofthefacingandturningtoolshowingthefrontandtoprake

Topofthefacingandturningtoolshowingthefrontandsiderelief

Left-handsideoftheturningtoolshowingthefrontclearanceandthetoprake

Topoftheturningtoolshowingthefrontandsideclearanceandthetoprake

GRINDINGATOOL

WhengrindingHSStoolstrytokeepthemascoolaspossibleIfan HSS tool becomes too hot and is then quenched in waterminutecrackswillformonthecuttingedgesThesecrackswillmakethetoolcuttingedgebreakdownveryquicklywhenusedThe best practice is to grind a little bit off the tool and thenquenchitwhileslightlywarmDonotletthetoolgethotdipitin thewater little andoften This should ensure the tool edgedoesnotbreakdowninuse

GrindingYourFirstTool

Most angles can be ground by using the tilting table whileothersmayneedtobefixedinrelationtotheperipheryofthegrindingwheelThefrontandsideofthetoolcanbegroundbytippingthetableatthecorrectanglewhereasthetoprakecanbegroundontheperipheryofthewheelThegrinder should first be switchedoff andunplugged Set

thetoolresttotherequiredangleusingthedigitalanglegaugeoranangletemplateandtightenuptherestBefore switching on the grinder ensure that everything is

freetorotatebyspinningthegrindingwheelbyhandIf all is well put on your safety glasses and switch on the

grinderPlacethetoolonthetoolrestupagainstthesideoftheprotractor Slide the tool along the table until it reaches thegrindingwheel andmetal starts to be removed Slide the toolbackwards and forwards slowly along the restwhile putting alittle light pressure on the tool so that it continues to pressagainst the grinding wheel When you have removed a smallamountofmaterialcoolthetoolbitdownAtnotimeallowthetool bit to get hot Continue grinding until you have removedsufficientmaterialfromthetoolbit

Thegrindingrestissettothecorrectangleof10degreestogrindtheendofthetool

Grindingthefirstangle

TurnthetooltotheotherangleanddothesamesothatnowboththefrontandsideclearanceangleshavebeengroundThis toolwill be enough for brass but for steelwe need to

grindthetoprakeWhengrindingthetoprakeonaright-handtool the slide rest needs to be higher than the centre of thegrinding wheel so that it grinds the tool at approximately 10degrees

Thefirstanglehasbeenground

You have now ground your first lathe tool The tool asreceivedfromthegrinderwillbetooroughtousehoweversoyouwillneedtohonethecuttingedgesYoucandothisonanoilstone(usedwithfineoillike3in1)orwithadiamondlaporusing a combination of the two Lightly lap the front and sideclearanceanglesuntilyougetagoodfinishand lightlyhoneaverysmallradiusonthetipofthetoolFinallyhonethetoprakeangleandyourtoolisreadyforuse

Grindingthesecondangle

Thesecondanglehasbeenground

AllofyourHSSturningtoolscanbedoneinthiswayOnlytheangleswillvaryandthesecanbesetusingadigitalanglegaugeandprotractorAnoccasionalhonewillresharpenyourtoolsaslongasyoutreatthemwithcareA similar range of HSS tools and a parting off tool all with

zero top rake shouldbeavailable if youwill be turningbrassUnless you are doing quantity production one tool holdershouldbesufficientforbrassAsatoolforbrasshasnotoprakeandyouwouldnotnormallygrindthetopawayaslongasyoubuy tool steel of the same size the tip height will remain thesameYoucanthenusethedifferenttoolsinoneholderwithouthavingtoresettheheight

MACHININGCASTIRON

Carbide-tippedtoolsareidealformachiningcastironAsimplebrazedupcrankedtoolwithasmallchamferonthenosewilldoforbothturningandfacingcastironcomponentsThemainuseof this tool will however probably be truing up the faceplatethat comes with the lathe The large diameter combined withtheintermittentcutovertheboltgrooveswoulddestroyanHSStoolinafewsecondsAsmalltippedboringbarwillbeidealfor

taskslikeboringcastironcylinders

Grindingthethirdangle

Asimplediamondlap

Thethirdanglehasbeenground

Tosharpentippedtoolsyouneedadiamondwheelorifyouwant to remove large amounts of carbide a silicon carbidewheeloftencalledagreengritwheelowingtoitsusualcolourSilicon carbide wheels are much softer than aluminium oxidewheels as they need to break down faster to present newsharpergrainstothecarbidetoolAdiamondwheelisonlydesignedtolightlylapatippedtool

itisnotsuitableforremovinglargeamountsofcarbide

Diamondcupwheel

TOOLHOLDING

Smallerlathessuchasarefoundinmostworkshopsmayhaveatopslidewithatoolclampforindividualtoolsablockwithasingle slot to take the tool a four-way turret (or sometimes athree-way)oraquick-changetoolblockandholdersetThereisalsotheso-calledAmericantoolpostwhichisaroundbarwitha slot through it and a bolt in the top to clamp the tool ItusuallycomeswithmatchingdishedwasherstoadjustthetoolheightThistypeisnolongerverycommononlathes

Quick-changeToolPost

Themostversatiletoolholdingsystemisthequick-changetoolblockwithmatchingholdersThedrawbackwiththissystemisthe cost of extra tool holders you need quite a few one foreachtoolThequick-changetoolblockmountsonthefrontofthelathe

normallyontopofthetopslide(Blockscanbefitteddirectlyon

thecrossslidebytheuseofaraisingblocktoaidrigidity)

Quick-changetoolblock

Each holder is set up with its own particular tool The toolholderscanbe individuallysetso that the turning tool isdeadoncentreheightandispresentedcorrectlytotheworkpiece

Quick-changetoolholder

Quick-change tool holders are available with a straight cutslottotakestandardsquareshanktoolholderswithastraightcutwiththeadditionofaVeecut-outinthebottomforusewithroundtoolssuchasboringbarsandasafrontpartingoff tool

holdertotakeahighspeedsteelpartingoffbladeRearpartingoff tool holders are available to take an inverted parting offbladeeitherahighspeedsteelbladeoran insertedtipbladeLeft-handed and right-handed extended tool holders are alsoavailableandmayoccasionallybequiteusefulThetoolblock isnormallymountedonthetopslidebutyou

cangetraisingblockstouseinsteadofthetopslideThismakesthetoolholderblockmuchmorerigidAbackquick-changetoolblockwillneedmountingonaraisingblock

Backofaquick-changetoolholdershowingthedovetailtypeofmounting

Right-handandleft-handextendedtoolholders

StandardtoolholderwithaVeetotakeroundtoolholders

Frontpartingofftoolholder

ToolClamp

Satisfactoryworkcanbedonewithatoolclampedontothetopslideusingshimsteel toset thecentreheightof the toolThemaindrawbacksarethatyoulosethepositionofthetoolwhenyoutakeitoffthetopslidetofitthenexttoolandyoualsolosetheaccuratecentreheightofthetoolunlessyoukeepthetoolandshimstogetherIfyouaremakingonlyonecomponentthisisnotaproblembutitisanuisanceifyouaremakingabatchofmatchingcomponents

Simpletoolclamp

Single-slotBlockToolPost

AblocktoolpostisoftensuppliedwiththecheaperlathesThetoolpostisliterallyablockofmetalwithaslotcutinittotakethe turning tool It is relatively easy to set the tool up at thecorrectcentreheightbyusingvariousthicknessesofshimThisisfineforthebeginnertoturningwhoisjuststartingoutbutitisbesttoreplaceitwithafour-waytoolpostoraquick-changetool post You could of coursemake several block tool postsandkeepeachonesetwithadifferenttool

Four-waytoolpost

Backtoolpost

Four-wayToolPost

Four-wayToolPost

Thefour-waytoolpost isagoodcompromiseona latheasyoucansetfourtoolsintheturretandrotateeachoneintopositionas needed This speeds up production and is a lot faster thanusingasimpletoolclampThedrawback isthatthetoolsstickoutof the turret fourdifferentwaysandyoumightcatchyourhandonasharp toolAsimple ratchetstopensures thateachtool repeats its position when the tool post is rotated so theworkisaccuratelyturnedeachtimethetoolisusedAduplicatefour-waytoolpostwithtoolsforbrasswillspeedupproductionevenmoreCastingsareavailabletomakeyourownthree-waytoolpost The three-way toolposthas theadvantageofbeingable to get close to the work when you are turning betweencentresFor the front tool post I would recommend right-hand and

left-hand roughing tools right-hand and left-hand finishingtools a tool groundup to face barswhile using a half centreand a Mini Thin inserted tip grooving tool with grooving andparting off inserts You will also need large and small boringbarsbothHSSandwithinsertedtipsTheHSStoolsshouldbegroundupforuseasgeneral-purposeturningtoolsformildsteelandsimilarmaterialsThecarbideinsertedtipboringbarshouldbefineforcastiron

BackToolPost

You can fit a quick-change tool block to theback of the crossslideaswellasthefrontSpecialholdersareavailabletotakeaHSSparting off blade or an inserted tip parting off blade Thebladewill be angleddown to give top clearancewhenpartingoffTheseback-mountedtoolblocksareveryhandyastheycanalsobefittedintotoolholderswithafacingtoolorachamferingtoolFor a back tool holder set-up I would recommend an HSS

partingoffbladeafacingtoolforcastironandadouble-ended45-degree chamfering tool that can be mounted parallel with

the chuck or at 90 degrees to it This set-upwill allow you tofaceaworkpiecechamfertheoutsidediameterandortheboreandpartitofftolengthThenextchapterlooksatholdingworkinachuck

5WorkholdingintheChuck

This chapter covers the different types of chucks how to usethemandsetupworkinthemaccurately

Aself-centringthree-jawchuckfittedwithlsquodrilljawsrsquoNotetheexternaljawswhichareinterchangeablewiththedrilljaws

USINGCHUCKS

Themostusefultoolsforworkholdinginthelathearethree-andfour-jaw chucks The three-jaw chuck is usually of the self-centringvarietythistypeofchuckcomesasstandardwithtwosets of jaws The first set of jaws are known as inside or drilljaws as they are most useful for holding round and hexagonbarsTheother setof jawsareoutside jawswhichholdworkusuallyindiscformontheoutsideSelf-centringmeansthatwhenyouinsertabitofbarintothe

chuck and turn the chuck key the chuck centralizes theworkpieceas it tightensup It isunlikely to runperfectly truebutitshouldruntruewithin3or4thouYou can also purchase soft jawswhich are exactly as their

namesuggestsYoucan thenbore themout to fit thework Ifyouborethemonthelatheyouaregoingtousethemontheworkwillrundeadtrue

Asetofsoftjawscanbeturnedorboredtosuittheworktobeheld

Aself-centringfour-jawchuckThesealsocomewithexternaljawsandsoftjawsareusuallyavailable

Self-centring four-jaw chucks can be used for square barsTheyarealsousefulforholdingroundbarswithmoregripthanathree-jawself-centringchuckSoft jawsarealsoavailableforfour-jawself-centringchucks

Afour-jawindependentchuck

Youare howevermuchmore likely to comeacross a four-jaw independent chuck than a four-jaw self-centring chuckIndependent means that the jaws can be moved individuallyand the jaws can also be reversed one two three or four ofthemdependingontheworktobedone

Abaseplatecastinginafour-jawindependentchuck

Wewillfirstlookatthethree-jawchuckThebestmethodofmaking a component in one of these is if possible to turn itcompletely at one set-up If you put a piece of bar into thechuck face the end centre drill drill and ream it skim thediameterandpartitoffitshouldbeconcentricalloverThisisbecausewehaveturneditallatthesamesettingwithouttakingit out of the chuck If we need to machine the other endhoweverwhenwe turn it roundandput it back in the chuckthechancesareitwillnotruntrueThis iswherethe four-jaw independentchuckcomes inYou

canput thecomponent intoa four-jawchuckandset it to runtrueusingthedialtestindicatorAnyworkyoudoonthepartedoff end should then be concentric with the rest of thecomponentWhensettingworkinafour-jawindependentchuckfor a second operation use some thin shimbetween the jawsandtheworkpiecetoavoidmarkingtheworkWorkisoftenheldinafour-jawchuckbecauseitisacasting

anoddshapeorsquareandsowonrsquotfitintoathree-jawchuckIf thework just requires tobe faced flat rightacross the facethereisnoneedtosettheworkrunningradiallytrueItshouldbe near enough on the centre line as long as the work is

reasonablybalancedYou could of course put the component into a three-jaw

chuckbyfittingsoft jawsandmachiningorboringthemouttotake the component This is the best option ifmaking severalcomponentsthatneedtobeidenticalbutifyouonlyneedoneor two components a four-jaw independent chuck will be thequickestmethodofmachiningthemLargerdiameterscanbeheld ina three-jawchuckbyusing

theoutsidejawsThesehavealargeradiusontheinsideofthejaw ifthisradiusis largerthantheworkpiecethejawsshouldnot tend to dig into the work and mark it Outside jaws areuseful forholding components like small flywheels locomotivewheels and chuck backplates when machining the bores ofholesorwhenmachiningacrossthefaceWhenmachining thindiscs it isuseful toputsomepacking

behindthedisctomakeitstandproudofthejawsTostopthepackingflyingoutwhenthemachineisrunningmakeasetofthree or four packing pieceswith grooves at each end and fittensionspringstothemTheyshouldallbethesamediametersothatthebackoftheworkisparalleltothechuckThelengthand grooves can vary slightly as they donrsquot affect theparallelismTheyarequickandsimpletomakesoacoupleofsets of different diameters should find their way intoeverybodyrsquostoolbox

AlthoughmostlathechuckkeyshavesquareendstheyareoftenofdifferentsizesKeepeachkeywithitsownchuck

ChuckKeys

I have alreadymentioned that the chuck key should never beleftinthechuckwhenitisunattended(seeChapter2)PutthekeyintothechuckuseitandputitsafelyawayassoonasyouhavefinishedwithitIfyouswitchonthelathewiththekeystillinthechuckyoumightneedatriptothehospitalDonotuseexcessive forcewhenyou tightenup the chuck

Do not use a piece of tube a spanner or anything else as alever thechuckkeyon itsownshouldbesufficient to tightenthechuckontotheworkWhenusinga four-jawchuckasmallchuckkey littlemore

thanaknurledknobwithasquareoncanbeusedtoadjustthejawsinandoutpriortotighteningupwiththeproperchuckkeyThiswill save timeover adjusting the jawswith a large chuckkeyTo turn the independent four-jaw chuck jaws round a

carpenterrsquosbracewithapieceofsquarebarinittofitthechuckwillmakeshortworkofreversingthe jawsbutdonrsquotuse it forthefinaltighteningasitisliabletostrainthejaws

STARTINGTOTURN

Before going any further you need to learn how to do basicturningFor thisyouneed toput the three-jawchuckonto themandrelStartbycleaningthemandrelwithacleanbitofragorsimilar(Ikeeparollofpaperkitchentowellingintheworkshop)Nowyouneed toclean thechuckrsquosboreand threadusing thetwotoothbrushmethod(seeChapter2)BoththemandrelandthechuckshouldbecleanbeforeyouattempttofitthechucktothelatheSelecting and grinding turning tools has already been

discussed (see Chapter 4) so by now you should have acorrectlygroundturningtoolsuitableforroughingoutapieceofsteelbar

Barwithapiptoolaboveorbelowcentreheight

MakingaToolCentreHeightSettingGauge

Thistoolneeds itscuttingedgesettothecentreheightofthelatheThereareseveralwaystodothisbutoneoftheeasiestiswith a home-made height gaugeWhen starting out this is achickenandeggsituationyouneedtomakethegaugetosettheheightbutyoualsoneedatoolsetatthecorrectheighttomakethegaugeThesimplestwaytoovercomethisproblemistosetthelathe

tooltotheapproximatecentreheightandtakeacutacrossthefaceofthebarDependingonwhetherthereisapipremainingon theendof thebaryoushouldgetan ideahow farout thetoolheightisIfthereisnopipthismeansthetoolisoncorrectcentre height or too high A pipmeans the tool is too lowOfcourse you may have been lucky so try dropping the toolslightly until a pip remains You can then raise the tool a fewthouatatimeuntilthepipdisappearsThetoolshouldthenbeoncentreheight

Barwithnopiptooloncentre

Nowthatthetoolisatcentreheightyoucanmakeasimpleheight gauge Turn a piece of bar down to as close to frac12in(12mm)asyoucangetandleaveitinthelathechuckMeasurefromthetopofthecrossslidetothetopofthebarwithacheapheightgaugeLowertheheightgaugebyhalfthebardiameterTheheight

gaugeshouldbeexactlyonthelathecentrelineMakeanoteofthisdimensionWe now need to look at how to turn a bit of bar to an

accuratediameterWhenturningabartosayfrac12in(12mm)youneedtostartwithsomethingslightlylargerInthiscasethiswillbe⅝in(16mm)diametermaterialasthisisastandardsizeCutapieceofmaterialabout2in(50mm)longandputitinto

thechuckwithabout1in(25mm)stickingoutSkimtheoutsidedown to about 0510 thou or 1225mm which is 10 thou(025mm) above the size required (You should be aware thatmosthobbylathedialsremovetwicewhattheysayaonethoudivisionforexamplewillusuallytake2thoufromthediameterLargercommercial lathesaremuchmore likelytotakeoffonethoupergraduation)Nowtakesmallcutsuntilalmosttosizeusingpowerfeedif

you have it andmaking sure you knock the feed off before ithitsthechuckStopthelatheandwindthecarriagetothestart

of the bar Take another cut at the same setting andmake anoteofthediameterTakeanothershallowcutbutthistimegoonly about frac14in (6mm) along the bar knock the feed off andturn the lathe off Move the carriage towards the tailstock sothat you can measure the bar Continue making this cut andmeasureuntilthesizeiscorrectThenrunthetoolalongthefulllengthof the jobWindthecarriagebacktowardsthetailstockand take a finishing cut or two at the same setting ThediametershouldnowbetheexactsizerequiredIt is not difficult to turn accurately it just takes a little

patienceandpracticeThemoreturningyoudotheeasieryouwill find it is to hold accurate limits If you turn everythingaccuratelywhetheritneedstobeaccurateornotyouwillsoonlearntoturnwithinathouorsowithoutanyproblems

Measuringtheheightofthebarabovethecrossslide

Now we need to make a tool height setting gauge Cut alengthofbarjustoverthedimensionsyouwrotedownandfaceone end turn it round in the chuck and face the other endMeasurethelengthandfindouthowmuchyouhavetotakeoffit to give the dimension you want Put the bar back into thechuck and bring the tool up to the face of the bar Lock thecrossslideFacethebartolengthbyusingthetopslideindexmovingforwardsafewthouatatimeuntiltherequiredlength

is reached Younowhavea tool height settinggauge suitableforthefrontandreartoolsIf you have an inverted Vee bed lathe or if for any reason

youcanrsquotusetheheightgaugeflatonthebedyoucanputtheheightgaugeonaplateon topof the lathebedwhileyouaresettingthetoolheight

Settingtheheightgaugetothelathecentreheight

Settingtheheightofthetool

Usingthesettinggaugetosettheheightofthereartool

TurningtoaSpecificLengthandDiameter

Nowwewill turnabarwithastepon theendToensure thatthestep isthecorrect lengthwewilluseabedstopThiscanbe as simple as a block clamped to the lathe bed to stop thecarriage moving any further I use a simple home-made bedstopthatdoesallIrequireSetthebedstopthenmovethecarriageuntilittouchesthe

stop and lock it Wind the top slide so that the tool is justtouching the end of the bar and lock the carriage For thisexercise we will make the step 16mm long and 12mm indiameterWindthetopslidealong159mmWecannowroughout thestepateachendTurn theenddown toabout02mmabove the finisheddiameterbywinding thecarriagebackandforthYoucanusethe fine feedbutmakesureyouknockthefeed off before the carriage reaches the stop and finish up tothestopbyhandWindthetopslidealongtheremaining01mmto12mmandfinishthediametertosizeandlengthtakinglightcuts as previously Donrsquot forget to clean up the face of theshoulderyouhavejustturnedIfyouneedtouseabedstopatthetailstockendofthelathe

asimplemethodofdoingthisistouseabarplacedonthelathe

bed against the tailstock The bar acts as a stop when thecarriageiswoundbacktowardsthetailstockThistailstockendbed stop is useful when you are turning a groove in acomponentandyouneedstopssetatboth theheadstockandtailstockendsofthelathe

Ahome-madebedstop

TurningWorkontheOutsideoftheInsideJaws

Theoutsideoftheinside(drill)jawsareusefulforturninglargerdiameterwork that is too large to fit inside thedrill jawsThiswillmostoftenbe in the formofa flywheelcastingFlywheelswithsixspokesareidealforturninginathree-jawchuckasthespokes can fit between the chuck jaws Ideally you need totighten up the flywheel until it is tight but not so tight as todistorttherim

TurningasteponabarusingthestopThebarisheldinthethree-jawchuckandsupportedwiththetailstockcentre

Ausefultailstockendbackstopmethod

Holdingaflywheelinathree-jawchuck

Holdingaflywheelintheoutsidejaws

To ensure concentricity you should do as much work aspossibleonthecastingatthesametimeYoushouldbeabletoturntheoutsiderimofthecastingfacetherimfacethebossand drill bore and ream for the crankshaft all at the samesettingAllyouneedtodothenistofittheoutsidejawsreversethecastinginthechucktapitgentlybackontothestepsoftheoutsidejawsandfaceacrossthesecondsideoftherimandthehubUseabitofshimtoprotecttheflywheeldiameterItdoesnotmatter if the flywheel runs exactly true or not as you areonlyfacingitparallelandtowidthnotturninganydiametersto

size

UsingtheSoftJaws

Soft jaws are very useful when a component has to run deadtrue in the jaws for example when making something like agrindingspindlewhereconcentricityisimportantSoftjawslikelytobefoundinthehomeworkshoparesimple

rectangles of steel with the scroll and groove formed directlyintothesoftjawsAnothertypeofjawyoumaycomeacrosshasa grooved pattern in the main jaws that matches a similarpattern in theactualsoft jawsThesoft topsof these jawsareusually interchangeable They are more likely to be found onlarger chucks but you could make your own version for thesmallersizesofchuckifyouwishThemain use of soft jaws is for second operationwork for

examplewhenyouhaveturnedacomponentcomplete fromabitofbarandparteditoffNowyouneedtoholdthecomponenttruetofinishoffthesecondendYoucandothisbyboringoutthechuckjawstotheexactdiameteroftheworkpieceToborethesoft jawstheyshouldbetightened inthesame

direction as they will be tightened in use so that they areoperatingonthesamepartofthechuckscrolleverytimeIfyouhaveathincomponenttomachinefitthesoftjawstothechuckandtightenthejawsontoabitofbarheldinthechuckBesureto leaveenoughspace in frontof thebarsoyoucanbore thejawstofitthework

BoringsoftjawstofittheworkThejawsareclosedontoanoddmentofbartoturntheshallowregistersothatittakesthework

AlwaysusethesamechuckkeyholewhentighteningupthejawsThisappliestoanythingyoudowithaself-centringchuckStampacrossoracentrepopmarkagainstoneof the jaws IsuggestdoingthisnexttojawNo1butanyonewilldoaslongas you always use the samemarked hole Youmight as wellmarkallyourself-centringchucksinthesamemannerCarefullyborethejawstotheexactdiameteroftheworkto

be machined Try to get it exactly on size Undo the jawsslightly remove the bar and replace it with the workpiecewhichshouldnowrundeadtrueAusefulmodificationtothesoftjawsistodrillandtapahole

inthemiddleofthejawsandfitanAllenscrewtoeachholeIfyouwant toholda longbar in thesoft jaws it isnoweasy toboreallthewaythroughthejawsratherthanjustboringastepor part way through All you need to do now is find a disc ofmaterial to put into the chuck ensuring there is sufficientmaterialleftontheinsideedgesofthechuckjawstoborerightthroughtotakethebar

Holdthedisconthescrewheads ifnecessarydrillthediscbeforeboringBorerightthroughthediscandthejawsuntilyouarenearlytosizeatwhichpointyoucanborethroughthediscand test the resultingborewith theworkpieceMakesureyouclean the bore thoroughly before trying the workpiece sinceloose dust can make the hole seem smaller than it really isWhentheworkpieceenterstheborefinishboringrightthroughthe jawsgo througha coupleof timesat the samesetting totakeoutanyspringintheboringbarYoucannowremovethedisc clean the jaws and put the workpiece right through thechuckcheckingthatitrunsdeadtrueThisoperationmaysoundtimeconsumingforasingle item

but if you have several components to make it will save aconsiderable time on setting up each bar individually to runtrue

BoringsoftjawsusingaringThesoftjawshavethreeAllenscrewsthatarecloseddownontotheringwhileboring

TurningtheoutsideofthesoftjawsusingaringThesoftjawshavethreeAllenscrewsthatareopenedupontotheringwhileturning

NowthescrewsareinplacewecanworktheotherwayroundandholdcomponentsontheoutsideofthejawsTodothisyouwillneedaringofasuitablesizeontowhichyoucantightenthejawswith the jaw loading acting outwards so any componentyouputontheoutsideofthejawswillberunningconcentricallyThiswill be ideal for itemssuchas tractionenginewheel rimsandotherlargehollowortubularworkpiecesOne other use for soft jaws is to hold irregular-shaped

components Put a piece of bar into the soft jaws and bore aholeofanysizeand thencleanup theboreso thatallof thejawsare true Transfer the chuck to themillingmachine tableandclampitdownUseatestindicatortocheckthattheholeinthechuckistrueYou can now mill a nest to take any irregularly shaped

component confident that when the chuck is returned to thelatheitwillberunningtrue

Plungertypedialtestindicator

Levertypedialtestindicator

DialTestIndicators

Therearetwomaintypesofdialtestindicatortheplungertypedial test indicator as its name suggests works on a plungerprinciplewhilethelevertypedialtestindicatorhasastylusonthe end The lever stylus is usually ball-or pear-shaped and isfixedtothedialtestindicatorwithafrictionfitmeaningthatitcanbemovedupanddownontheendofthedialtestindicator

throughawidearctoputitintothebestpositionforuseThe plunger type dial indicator usually has a maximum

plungermovementoffrac12in (12mm)butplungermovementsofupto2in(50mm)areavailableTheplungertypedialindicatoris non-reversing and needs an adaptor to enable it to clockholes true Instead of a stylus it has an interchangeable endoften with a ball fitted various interchangeable ends areavailableoryoucanmakeyourownThe lever dial test indicator has a much smaller range of

travelarangeof0008in(02mm)isverycommonItisusuallyeither self-reversing (itmoveswhen in contact with theworkdependingonwhichwayitismoving)oritmaybereversedbyusinga lever on the sideof thedial test indicator both typesarequite commonSince the stylus isdelicate combinedwithitslimitedtravelrangeyoumustbeverycarefulnottobreakitAplungerdialindicatorcanbeusedasadirectreadoutofthe

travel and will be found to be very accurate Owing to therelativelylongtravelifyouwantedperhapstooffsetthecentreofabitofbar in the four-jawchuckby0125in (318mm) thiscanbedonebyturningthechuckbyhandandsettingthebaruntil the indicator travel shows 0250in (635mm) which is0125in (318mm) offset The lever dial test indicator is of nouseforgivingdirectreadingslikethisbutshouldbeusedasacomparatorwherethereadingtakenisforexamplezeroatallpointsofthetravelThedial test indicator is usuallymounted on amagnetic or

vacuum base but is sometimes fixed to a block that can beclampedtothelathemostoftenonthecrossslideSometimesthedialtestindicatorcomesasacompletekitincludingvariousmountingcomponents

Clockingtheendofacastinginafour-jawchuck

Four-jawChuck

To set thework up in an independent four-jaw chuckwe firstneed to know what part of the workpiece should be on thecentre If theworkpiece is a castingwemay have an outsidediameter or a hole that needs to run true in this case wewould put a dial test indicator onto the work and adjust thechuckalittleatatimeuntilthediameterrunstrueDonotturnthe chuck with the indicator in the hole Instead wind thecarriage forwards until the clock enters the hole and take areadingWind thecarriageback rotate thechuck90degreeswindthecarriageforwardandtakeanotherreadingAdjusttheworkinthechuckuntilitrunstrue

WhereacastingisstickingoutashereyoushouldtrytosupportthecastingwitharunningcentreThiswillhelptostopthecastingshiftinginthechuck

LatheCentreFinder

If there isnodiameterorholeyoumayhave tomarkout thecentreontheworkusingaheightgaugeandcentrepopitwithacentrepunchThenyoucanuseawobblerandatestindicatortosettheworktrueItwasoncepossibletogetalathecentrefinderconsistingof

a bar about 6in (150mm) long pointed at both ends with auniversaljointabout1in(25mm)fromthefrontendInusetheshortfrontendgoesinthecentrepopoftheworkinthechuckWhen you rotate the chuck by hand the pointed short endfollows the eccentricity of the centre hole which ismagnifiedaboutsixtimesatthetailstockendYouthenjusthavetoadjustthechuckuntilthetailstockendisrunningtrueatwhichpointthe centre in the work will also be running dead true I donrsquotknow anyone who makes these and second-hand ones areextremelyrare

Asimplehome-madecentrefinder

You can make a simple version of this that works well byusingamillingmachinepointedcentrefinderThisisaparallelbarwithaseparatemoveablepointedendThetwocomponentsare held together with a spring inside You need the pointededge finder a Morse taper parallel adaptor (the Morse tapershould fityour tailstock)aspringandashortstubofbar thatwillfitinsidethetaperedholderrsquosboretostopthespringgoingrightthroughPuttheshortstubofbarintothetaperinsertthespring follow up with the centre and put the Morse taperadaptorintothetailstockBringthetailstocktowardsthechuckuntil the centre of the centre finder is in the centre pop ThespringwillholditinplaceTousetheimprovisedcentrefinderput a dial test indicator onto the parallel part of the centrefinderrsquospointandrotatethechuckbyhandThepointwillrotateeccentricallyadjust thechuckuntil thecentre finderrsquospoint isrunningtrue

Usingascribingblockwithadialtestindicator

Move the tailstock along the bed until the point of thewobblerisinthecentrepopontheworkPutthetestindicatoronthefrontdiameterofthewobblerandadjustthechuckjawsuntilthewobblerisrunningtrueWhensettingupacastingorsomethingsimilarwherenotall

of the diameters are machined you should use the dial testindicator on diameters thatwill not bemachined such as theinsideofaflywheelrimWhenyouhaveturnedallthefinisheddiameters they should then be true with the unmachineddiametersSetting work in the four-jaw chuck depends on the

componenttobemachinedIfyouareusingroundmaterialyoucansetittoruntrueusingadialtestindicatorHoweverifyouaresettingaroughcastingthevariationofsizeandroughnessofthecastingsmaywellbeunsuitableforadialtestindicatorThere are alternativemethods of settingwork up in a four-

jawchuckespeciallyforcastingsOneofthesimplestmethodsis toholdasquarebar in the lathetoolholderandusethis tosetthejobtrueInuseyouwindthebaruptotheworkandsetthedial tozeroorotherwisemakeanoteofwhere it isWindthebaroutorawayfromtheworkTurnthechuck180degreesand wind the bar up against the work again You can

immediatelyseewhichwaythebarneedstomovesothatitisrunningtrueAdjustthecastinginthefour-jawchuckandmovethecastingtowardsthecentrepointRepeatuntilthecastingisrunning true This method is also useful if you are setting asquarebar to run true Justcheckeach faceof thesquarebarwiththebitofmetal

Settingacastingbyusingasquarebar

StickyPinMethod

An alternative the sticky pin method is especially suited tolocomotive wheels or flywheels An ordinary household pin ismounted in plasticine or Blu-tack perhaps stuck on the lathetool and is arranged to point to the inside diameter of thewheelor flywheel thearea that isnotmachinedbut is leftascastAdjustthecastinguntiltheunmachinedfaceisrunningastrueasyoucangetitandthewheelisreadytoturnThestickypinmethodisalsousefulforsettingupworkthathasachuckingspigot such as a locomotive smokebox door Just hold thechucking spigot in the four-jaw chuck and adjust the castinguntilitrunstrueontheoutsidediameterandthefrontface

Usingacommercialstickypintosetworktrue

Themethodsofcentringworkinthefour-jawchuckthathavebeen discussed are also suitable for setting work true on thefaceplate The next chapter looks at turning between centresandusingthefaceplate

6TurningbetweenCentresandFaceplateWork

Thischapterdealswithbasicturningbetweencentresandthenintroduces turning with the work mounted on the lathefaceplate

Headstockcentreanddriverplate(alsoknownasacatchplate)

TURNINGPLAINBARSBETWEENCENTRES

The most basic way of holding work for turning is between

centres Turning between centres is literally holding thecomponenttobemachinedbetweentwocentreseachofwhichhas a 60-degree included angle The headstock centre usuallygoes round with the headstockmandrel although some olderlatheshadanon-rotatingcentreandthedrivetotheworkwasbyapulleymountedontheworkThetailstockcentreisoftenafixedcentrethatdoesnotgoroundalthoughcentreswithballbearingscalledrunningcentresarereadilyavailable

Tailstockplaincentre

The component to be turned usually a shaft has a female60-degreecentreinbothendsthatisusedtosupporttheworkThe work can be turned round between centres so that bothends of the shaft can be machined Because the work ismountedbetweencentresbothendsoftheworkwillbetruetoeachother

Tailstockrunningcentreso-calledbecauseitrunsonballraces

CentringtheBar

FirstwehavetoputthecentresintoeachendofthebarIfthebarisshortsayuptoabout6inlongholdtheworkinthethree-jawchuckanduseacentredrillinthetailstockdrillchucktoputacentre intothebarAcentredrill isashortdrillwithasmallpilot on the end that has a 60-degree taper to the bodydiameterAbettermethodof centring thebar especially longbars is by using a three-jaw chuck and the fixed steady Thebarisheldinthethree-jawchuckwiththeotherendsupportedin the fixedsteadyand thecentre is formed in theendwithacentredrillAusefultoolthatcanbeusedtofindthecentreoftheshaftis

thecentresquarewhichisametalbladewithaVeeonitthatlocatesonthediameterofthebarMarkalineacrosstheendofthebarwitha scriber turn the centre square90degreesandthenscribeanotherlineWherethetwolinescrossisthecentreof thebar Tomake it easier to see the scribed linesblackenthe end of the bar with a permanent felt tip marker beforescribingCentrepunchthepointwherethetwolinescrossandput a 60-degree centre in each end of the bar using a centre

drill in a power drillHold thebar in a bench vicewhile doingthisPutacentredrillintothetailstockdrillchuckandinsertthebar in the three-jaw chuck Make sure the lathe is on a lowspeedabout300rpmwindthetailstockinandjustlightlycleanupthecentreholewiththecentredrilltotrueitupAnotherusefultooltofindthecentreofabarisabellcentre

punchThiscomprisesaconewithacentrepunchinthemiddleIn use place the bell end on the end of the bar and tap thecentrepunchwithahammertomarkthecentreTheendofthebar though needs to be reasonably square if using the bellpunchmethodThere are other similarmethods of centring bars but those

givenherewillbealltheturnerneedstolearn

Turningbetweencentres

Centringthebarusingthefixedsteady(Notethatthefrontclampisnormallydoneupwhileinuse)

Asimplecentresquare

Crosssectionofbellcentrepunch

MachiningtheBar

NowweneedtomountthebarbetweencentresThisissimplyamatterofputtingthebarbetweencentresandtighteningthetailstocksoitislightlypressingintothecentreintheendofthework To drive the work a carrier is fixed to the shaft andengagesapininacatchplatemountedonthelathemandrelAcatchplateissimplyablankdiscwithapinstickingouttodrivethecarrierthat isfittedtotheworkThecarrier isfittedtotheworkusinganAllenscreworboltTostopanymovementofthebarinrelationtothecatchplatethecarriercanbewiredtothecatchplatepinThiswill stop thecarrierand thework flappingaboutItisparticularlyimportanttostoptheworkfrommovingin relation to the catchplate when screwcutting betweencentres

Facingoffabarusingthehalfcentre

Nowthatthebarissafelymountedbetweencentreswecanstart turning it tosizeNormally the first thing todo is to facetheendsofthebartothefinishedlengthDecidewhichendofthebarhastheshallowercentreWewillmachinethisendfirstYouwillneedahalfcentreso-calledbecausealmosthalfofthecentre is missing This means the lathe tool can reach rightacrosstheendoftheworkwithouttouchingthehalfcentreWhenusinganyfixedcentreinthetailstockputabitofoilor

grease into the centre before use and top up as necessaryLightlywindthetailstockbarrelagainstthecentreandlockthebarrel so it canrsquotmoveSwitch the latheonandwind the toolacross to clean up the end Reverse the work and clean theotherendupat thesamesettingBothcentresshouldnowbethesamedepthMeasuretheoveralllengthofthebarTakethefinished length required from the overall measurement youhavejustmeasuredDividethisbytwoandthisishowmuchweneed to take off each end of the shaft so it finishes at therequiredlength

Askimmedbar

Ifyouhaveonechangethetailstockhalfcentretoarunningcentre if you donrsquot have a running centre change to a fixedcentreThehalfcentreshouldonlybeusedwhenfacingtheend

of the bar We will nowmachine the rest of the bar For thepurposeofthisexamplewewillassumethebarhasafinisheddiameter in themiddle with a step at each end First we willmachine the overall diameter to size To do this we need toskimthediameterandcheckthesizeTakeafinecutalongthebarusingthefinefeedifyouhaveoneMeasurebothendsofthebar Ifyouhavesetthelatheupcorrectly(seeChapter2)thebarshouldbeparallelIfitisnotadjustthetailstockbeforecontinuingAssumingthebarisparalleltakeanothercutortwosothatyouareabout01mmlargerthanthefinisheddiameterNowmove the tool in until almost at finished size and take alight cut about 10mm long along the bar Repeat this cut toensure the tool is notpushingoffMeasure thisdiameter youwill probablyhave towind the tailstockbarrel back toget themicrometerontotheendofthebarOnlymovethebarrelbackdo not slide the entire tailstock backMeasure the bar to findouthowmuchtoremovefromthediameterTakeanothershortcutandcheckforsizeWhenthebariscuttingtosizemachineall thewayalongYouwillprobablyhave to take twoor threecuts at the same setting until the bar ismachined to finishedsizeNowwewill turn the stepson theends Toensure that the

stepsare thecorrect lengthwewilluse thebedstopSet thebedstopthenwindthetopslidesothatthetoolisjusttouchingthe end of the bar For this exercise we will make the steps12mm long Wind the top slide along until the tool is justtouching the end of the turned bar Wind the top slide along119mmWecannowroughoutthestepateachendTurntheenddowntoabout02mmabovethefinisheddiameterYoucanusethefinefeedbutmakesureyouknockthefeedoffbeforethecarriagereachesthestopandfinishuptotheendbyhandRepeat for the other end Wind the top slide along theremaining01mmto12mmandfinisheachendinthesamewayasyoufinishedthemaindiameterDonrsquotforgettocleanupthefaceoftheshoulderyouhavejustturnedCongratulations you have just turned an accurate shaft

Donrsquotworryiftheshaftisatinybitundersizeyoucanprobably

makethematingholestofit

Thefinishedshaft

Usingachuckandarunningcentre

Usingthemethodsetoutaboveyoushouldnowbeabletoturn any shaft you require within the capacity of the lathe Avariationoftheabovemethodwheretheshaftissingle-endedistoholdoneendinthethree-orfour-jawchuckandsupporttheotherendwithacentreinthetailstock

Alargefaceplatesmalleronesareavailable

FACEPLATEWORK

Another basic way of holding work is on the faceplate Thismethod is used when the component is too large or isawkwardly shaped andwould be difficult to hold in a three-orfour-jaw chuck Usually the work is clamped directly onto thefaceplate often with a packing piece behind it to protect thefaceplateThefaceplateshouldbeflatandtruesothefirstthingtodo

whenyougetthelatheistocheckthefaceplatewithadialtestindicatorCarefullycleanthemandrelnoseandtheinternalholeinthefaceplateMakesurethemandrelcanturnfreelybyhandwith the lathe switched off and check that the face of thefaceplateisrunningtrueasclosetotheouteredgeasyoucanget If it is runningtrue runthetest indicatoracross the frontfaceofthefaceplatethisshouldbetrueaswellIfthefaceplateis running out itwill need to bemachined Put the lathe intobackgear if ithas it (topbackgearwillprobablybe fine)Youwill need a carbide-tipped tool ideallywith a small 45-degreechamferonthetipBringthetooluptothefaceplateand lockthe carriage Next you need to lightly face the faceplate right

acrossitsdiameterIfyouhaveapowercrossfeeditwillmakelight work of this but if not you can feed across by handFortunatelymost faceplateshavea series of rings on them toaid in setting up the work Machine the faceplate from theoutsidetothefirstringandstopforarest feedtothesecondring and so on until finished Depending upon how badly outyourfaceplateisyoumayhavetodothismorethanonceuntilit iscleanedupbutwhen it isdoneyouwill rarelyneedtodothisexerciseagain

Machiningaholeinablock

Asmentionedpreviously the ringsmachined on the faceplateareguidestohelpyousetuptheworkThiswilldoiftheworkisaroundcomponentbutweneedadifferentmethodiftheworkis square Take a block of metal for example that has beenmachinedalloverWewanttomachineaholeinit2infromoneedgeand1in fromanother edgeMarkout thepositionof theholeandcentrepunch it Put adeadcentre into the tailstockholdtheblockontothefaceplatebringthetailstockuptowardsthechuckandlockitWindthetailstockbarrelandcentreuptothe component and engage with the centre pop Lock thetailstock barrel Clamp the block to the faceplate using somepackingpiecesandfourclampsontheblockTheholeisnowoncentreandwecanmachineitinthecorrectplaceIf we need more than one hole placed accurately in the

componentwecanusetoolmakerrsquosbuttonstoensuretheholesare in the correct place Toolmakerrsquos buttons usually come insetsof fourOnebutton isusually longer than the rest soyoucanstillclockthediameterwhenitisclosetoanotherholeSetsare often available second-hand on eBaywhile they probablyhaveanobscureAmerican threadyoucanclamp themto theblock using your own BA or metric screws together with awasher

Settingupthefaceplateusingthetailstock

Asetoftoolmakerrsquosbuttons

Tofitthemtothecomponenttobeboredmarkoutdrillandtap holes in the approximate positions where the holes areneeded If you need a pair of parallel holes place thecomponentonasurfaceplate looselyfitthebuttonsandpushthem down onto a parallel or similar block of the correctthicknessandnipthescrewsupThespacershouldbesmallerthanrequiredbyhalfthediameterofabuttonIftheholesneedtobeacertaindistanceapartuseaspacer

of the correct size between the buttons (Remember tomake

thespacersmallerbyonediameterofthebutton)

Settingupacomponentusingtoolmakerrsquosbuttonstogetafixeddistancefromtheedgeofacomponent

TherearelotsofdifferentwaystosetthespacingofbuttonsItismainlyamatterofcommonsenseCastingsandflatcomponentscanbeboltedtothefaceplate

for machining A typical example of a flat component is aneccentric strap This type of component is usually made of acomponentthatiscutinhalfandboltedbacktogetherAholeisthenboredinitonthecentrelinetofittheeccentricThistypeofcomponentisoftendifficulttoholdinthelathechuckandisprone to distortion Castings are often too large to fit into alathechuckandso the faceplate iscalledon toundertake theworkAcastingcanoftenbebolteddirectlytothefaceplatetofacilitateeasymachining

Settingupacomponentusingtoolmakerrsquosbuttonstogetafixeddistancebetweenthecentresofacomponent

Work on the faceplate is often an odd shape or is set off

centreThiscauses it tobeunbalancedandasaconsequencethe lathemayvibratewhile thework is turningTocounteractthis tendency the faceplate should be counterbalanced byboltingweightsontoitAusefulsourceofweightsisthelathersquoschange wheels By bolting a change wheel or two onto thelightersideofthefaceplateyoucanbringthewholeassemblybackintobalanceAfterboltingthechangewheelsonspinthelathe by hand to check the balance The faceplate should notshowatendencytostopatoneparticularpointWhenyouarehappy that the faceplate is in balance the work and balanceweightsareboltedontightlyandsothattheworkdoesnotfoulthe lathewhen turnedbyhand switch themachine on in lowback gear to check for vibration Depending on what you areturning you should be able to run in top back gear or evenbottomdirectspeed

Asimpleclampsetisveryusefulwhenmachiningacastingonthefaceplate

TurningaFlywheel

Oneofthemainusesofafaceplateisturningalargediameteriron casting typically a flywheel or a locomotive wheel for asteamengineTheflywheelshouldbemountedsothattheinneredgeoftherimandtheouteredgeofthehubruntrueIfeitherofthemrunsoutitwouldbebetterthatthehubrunsoutasthe

rimwillbemorenoticeableonthefinishedengineClamp the flywheel down with some packing under the

spokessothatyoucanturnrightacrosstherimBecarefulthatyouclamptheflywheeltightenoughsothat itdoesnotmovebutnotsotightthatitdistortsRoughturn theoutsidediameterand facetherimusingthe

backgearUsingadirectdrivespeeddrillandborethecentrehole and either finish off with the boring tool or use a reamDonrsquot try reamingwithout boring the chances are that if youdotheholewillnotbetruewiththerimasthedrillprobablydidnotcutanaccurateholeDropdowntothetopbackgearspeedface the rim and turn the outside of the rim to the finisheddiameter Turn the flywheel over and finish the other face towidth

Astubarborsuitableforcentralizingalocomotivewheelorflywheel

TurningLocomotiveWheelFlanges

LocomotivewheelflangescanbeturnedonafaceplateYoucanpurchase blank end Morse taper arbors that fit into theheadstocktaperFitoneoftheseandturnaspigotonittotake

thewheel bore Thewheel bores should all be the same sizebut if they are different sizes machine the spigot to fit thelargestboremachinetheflangeonthatonethenmachinethespigotdowntofitthenextonemachinetheflangeandsoonIdeally the wheel bores should all be the same size but if

theyarenotproceedas followsSkimtheoutsidediameterofthe wheel flangemeasure and take it to the correct finishedsizeMovethelathetoolinbythedepthoftheflangeandturnthe tread Deal with all wheels like this machining all of theflangeoutsidediameterstothesamesizemovinginthecrossslidebythesameamounteachtimesothatallthetreadsendupthesamesize

UsingtheKeatsVeeangleplatetoturnaneccentriccomponent

KeatsVeeAnglePlate

TheKeatsVeeangleplate ismountedon the faceplateand isusedtoholdroundbarsquarebarandmiscellaneouscastingssuch as cylinders and steam chests The angle plate can bemountedanywhereonthefaceplateaslongasthelathecanbe

rotated safely and is in balance When spun by hand thefaceplateshouldnotshowatendencytostopatanyparticularplacewhenrununderpowerthelatheshouldnotvibrateAswellasholdingbarandcastingsforturningtheKeatsVee

angleplateisveryusefulformakingeccentriccomponentssuchastheeccentricsforasteamengineTo turn an eccentric use a test indicator to check that the

roundbarisrunningreasonablytrueWhenthisissatisfactoryyoucanturntheoutsidediameterofthebartofittheeccentricstrap (or component) including any step or groove requiredNextoffsettheKeatsVeeangleplatebytheamountyouwantthe eccentric lsquothrowrsquo to be Use the dial test indicator tomeasure the offset of the outside of the eccentric The offsetshouldbetwicethethrowYoucannowdrillboreandreamtheholeintheeccentricYounowhaveenoughbasic knowledge to carryout turning

between centres andwork accurately on the faceplate In thenext chapterwewill lookat holdingwork in a collet andonamandrel

7ColletsandMandrels

Thischapterexplainsallaboutholdingworkinacolletandhowyou canmake and use several different types of mandrel forworkholding

ERcollets

USINGCOLLETS

Quite a few different collet systems are to be found inworkshops Some are used for holding tools such as millingcutterssomeareusedforbarorworkpieceswhilesomemaybeusedwithbothbarandworkpiecesOne of the commonest is the ER collet which comes in

severaldifferent sizeseachhavingadifferent largediameterTheERcolletsystemallowsupto0039in(1mm)collapseofa

colletalthough in thesmaller sizesyoucanbuy thecollets in05mmincrementsA16mmcolletforexamplewillholdroundmaterialdownto15mmdiameterWhatevertheERcolletsizetheyallappear togodownto1mmminimumwhichwillclosedownto05mm

ERcolletadaptor

TherearemanytypesandsizesofERholderavailableAlltheusualMorse taper shank sizes are available and you can alsobuyvariousdiametersofextendedparallel shankholdersTheproblemwiththeseisthattheyaregreatforholdingtoolsthathave a short shank but because you need to use the holderwithadrawbaryoucanrsquotputlongbarstockrightthroughthemTo overcome this for lathe work you can also buy ER colletholdersdesignedtobefittedtoachuckbackplatethatyoucanmachine to suit your lathe so ensuring good concentricityBecause they donrsquot use a drawbar you can fit bar stock rightthroughandintotheheadstockmandrel

ERcolletadaptorfittedtoabackplateIalwaysleavebackplatesoversizesoIhavesomethingwithwhichtoclampthemdownwhenusedonamillordrill

When buying new and second-hand ER collets make surethey have the retaining groove near the nose end The older(andobsolete)EandEScollet typesdonothavetheretaininggrooveandarenotinter-changeableYouaremostlikelytofindEandEScolletsincludedwithasecond-handUnimatlatheDraw-in collets are usedwith a drawbar or collet tube The

drawbardrawsthecolletuptightbydrawingit intothelathersquosmandrelbyabar that runs through thecentreof themandreland screws into the centre of the collet Thismeans that youcannotputbarstockrightthroughthecolletToovercomethissome Morse taper collets use a hollow draw tube the collethaving an external thread tomatch the internal thread of thedrawtube

Draw-incollet

Special collets are made for the Myford ML7 Super 7 andML10 lathes These are Morse taper collets but rather thanhavingadrawbartheyareclosedwithanoseringthatfitsoveragrooveinthecolletThenoseringtightensthecolletintotheheadstockmandrelrsquos Morse taper It is extracted after use byundoing the nose piece which draws the collet out from theMorsetaperbythenosegrooveImperialandmetriccolletsareavailableuptofrac12in(12mm)diameterDead lengthcolletsareavailable that fit intoanattachment

usually fixed to the front of the lathersquosmandrel These colletsarecalleddeadlengthbecausetheydonotmovelongitudinallyunlike draw-in collets You are more likely to find collets likethesesecond-handratherthannew

BoxedsetofMyfordcollets

Deadlengthcollet

AvariationofthedeadlengthcolletistheCrawfordMultiborecolletThissystemhascolletsmadeofsegmentsheldtogetherbyspringsThecolletsareofvariablediameterandhavequitea

largeclosurerangeTheyaremorelikelytobefoundonalargercommercial lathe although you can get collets for smallermachinesWatchmakerrsquoscolletscanbeused inmost lathesbymaking

an adaptor for the headstock and a drawbar (or tube)Watchmakerrsquos collets are very accurate and can go down toverysmallsizesbuttheyhavelimiteduseinmostworkshopsYou can get a special watchmakerrsquos spindle for the EmcoUnimatlatheandthereisalsoaversionoftheCowellslathetheCW90thattakeswatchmakerrsquoscolletsFormost of thework carried out on the lathe youwill find

thatanERholder thatmountsontoachuckbackplate ismostuseful

Simpleexpandingmandrel

Simpleplainmandrel

MAKINGMANDRELS

There are several types of mandrel in common use inworkshops The most common is probably the expandingmandrelwhichcaneasilybemadeinanyworkshopInitsmostbasic form it is a bar turned to a size to fit the bore in theworkpieceItisthenthreadedwithataperedtapandslitat90degrees togive foursegmentswhichare thenexpandedbyascrewfittedintotheendofthemandrelAnother common mandrel is the tapered mandrel This is

usuallyalsquobetweencentresrsquomandrelandisoftenmadetotaperfromjustacoupleofthouovernominalsizetoacoupleofthouunder nominal size It is usually hardened and has a groundfinishTheworkpieceisheldinplacebybeingpushedontothemandreluntilitistightToremoveitjustpressitbackoutthewayitwentinWhereconcentricityisnotquitesoimportanttheworkpiece

canbeputonaplain turnedmandrelandtightenedupwithaboltandflatwasherExpandingmandrelsarealsomadecommerciallybutasyou

need a mandrel for each individual size of hole it can getexpensive if you need more than one or two different sizesCommercialmandrelscanbeobtainedwithMorsetapershanksto plug straight into the headstock Thismethod ensures thatthe mandrel should run dead true assuming both the Morsetapermandrel and theMorse taper in the headstock are bothcleanandfreefrommarksorswarfYou can also purchase Morse taper arbors with blank end

pieces from which to make your own mandrels First we willmake an expandingmandrel from a blank Morse taper arborYouwillneedtoturnthearbordowntofittheworkpieceboreIusually turn themandrelabout0010in (0025mm)oversize tostartwithandthenIdrillandtapthearborwithataperedtapThe drilled hole can go quite deep but the tapped hole onlyneedstogoinuntilthelockingbolt isabouthalfwaydownthelengthwheretheworkpiecewillsitPut the mandrel into the vice and cut along the mandrel

making four cuts around the circumferenceRetap thehole to

cleartheswarf fromthethreadandputthemandrelback intothe headstock taper Now you can lightly nip the screw up toexpandthemandrelslightlySkimthemandrel to finishedsizeuntil the workpiece will fit on without shake You can nowfurther tighten the screw so that the workpiece tightens ontothe mandrel When you slacken the screw the workpiece willcome off easily as you have skimmed it while it was slightlyexpandedYoucanmakeanexpandingmandrelfromabarheldin the three-or four-jawchuckorperhapsacollet inasimilarway Ifheld inachuck itmaynotgoback true ifyouneed touseitagainsoifpossibleyoushouldholdthearborinacolletFor aplainmandrel turn thediameter to fit theworkpiece

anddrillandtapforacapscreworaboltThereisnoneedtosplit this type ofmandrel You simply put the workpiece ontothemandrelandholditonwithaflatwasherAgainitdoesnotmatterwhetheryouuseabarinachuckorcolletorifyouusea Morse Taper blank arbor Arbors are very useful in theworkshop If youmake them fromMorse taper blanks or holdtheminacollettheycanbeusedoverandoveragain

8TaperTurningandLatheAccessories

Thischapterexplainshowyoucanturnataperusingatopslidetheuseoffixedandtravellingsteadiesandformtools

Turningataperwiththetopslide

TAPERTURNING

SometimesyouwillhavetoturnataperintheworkshopThatisa fairly easy jobWhat ismore difficult however is having toturnmatchingmaleandfemaletapers

Themethodyouaremostlikelytouseintheworkshopistoturn the two tapers with the top slide You should be able toturna taper longenough foraMorsetaperusingthismethodThemostimportantthingwhenturningtapersistoensurethatthe tool tip is at the exact centre height of the lathe This isbecause the taper will vary if the tool is not dead-on centreheightProbably the easiestmethod of turning aMorse taper is to

useadial test indicator toclocka lathecentreof therequiredMorse taper between centres The smaller end of the tapershouldbeatthetailstockendofthelatheThetopslideshouldbewoundalongthetaperby itshandwheelwhilethecarriageremainslockedThetopslideshouldbeadjustedangularlyuntilthedialtestindicatorreadszeroallthewayalongNowyoucanfinish turn the external Morse taper using an internal MorsetapersleeveasagaugetocheckthattheangleiscorrectTodothis make marks with a felt tipped pen along the taper andcheck that the test sleeve rubs evenly all the way along themaletaperAdjustifnecessaryuntilyouhaveaperfectfitToturnthematchingfemaletaperthelargeendofthetaper

willbeat the tailstockendand theboringbarwillbe invertedandcuttingon thebackof theholeDoing thismeans thataslongasbothofthetoolsareatcentreheightthetapersshouldmatchWecanusethemaletaperthathasjustbeenturnedasatestbarBoreoutthetaperverycarefullyyouwonrsquotneedtoremovemuchmaterial before the test taper goes too far intothe finishedbore Testwitha felt tippedpenuntil youhaveaperfectfitYou can turn any taper you need this way you are not

restrictedtoMorsetapersAnothermethodmostoftenusedforlongshallowtapersistouseataperturningattachmentTheseattachments are often available as extras on higher qualitylathes They comprise a slide mounted onto the back of thelathe Often the guide is dovetailed with a sliding blockattached to the cross slide to guide the tool on a taper ThedepthofcutisusuallyputonusingthetopslidesincethecrossslideisusuallydisconnectedfromthefeedscrewInthiswayit

isfreetomoveinandoutcontrolledbytheguide

Taperturningattachment

Settingthetopslidebyclockinganexistingtaper

Anothermethodweshalllookatfortaperturningistooffsetthe tailstock on its base This will make the work turnedbetween centres become tapered either large or small at thetailstockenddependingonwhichwaythe tailstock isoffset ifsettowardsthebackofthelathethediameterwillbelargerat

the tailstock end if the tailstock is moved to the front thetailstockendwill be smaller indiameter Theamountof taperthatcanbeturnedinthismannerislimitedsincetheheadstockandtailstockcentresareoutoflineThe final method of offsetting the workpiece is by using a

boringhead inthetailstockYouneedahome-madehardenedsolidcentrethatfitswheretheboringtoolwouldnormallygo(AsmallUnimatlathesizerunningcentremightbeideal)SettheboringheadsothetooltravelishorizontalYoucanthenoffsettheboringheadcentresocreatingataperThisisthesameassetting the tailstock over but you donrsquot have to realign thetailstockafterwards

Usingthefixedsteady

USINGFIXEDANDTRAVELLINGSTEADIES

The fixedsteady isusedmainly to turn theendofabaror tocentre a workpiece that is too large to fit through the chuckObviously bar stock should not protrude from the chuckmorethan is necessary to work on This is where the fixed steadycomesinThefixedsteadycanbesettothediameterofthebarsothattheendofthebarcanbemachinedsafely

Thesteadycanbesetusingachuckmountedonthistailstockadaptor

Travellingsteady

Settingthesteadybyusingachuckmountedonanadaptor

Onewaytosetthefixedsteadytosizeistoturnabitofbarin the chuck to the same size as the barwewant to use thesteadyonThenwecanmovethefixedsteadyalongthelathebedandfittheworkpieceintothechuckandinthesteadyTheendof thebar nearest to the tailstock shouldnowbe runningtrueandcanbeworkedonsafelyThebarcanbecentredrilledfacedorotherwiseworkedonAn alternative way to set the steady is to support the

tailstockendof thebarwitha threejawchuckmounted in thetailstockAdaptors to take the threejawchuckareavailableoryoucouldmakeyourownJustsupportthebaratbothendsinthethreejawchucksandsetthesteadyfingerstothebarThe fixed steadycanalsobeused to support tubes thatdo

nothaveanymaterialinthecentreThe fingers of the steady need to be lubricated regularly

while inuseThis iseasilydonebydrillinga smallhole in thetopfingerwithacountersinkinsidetheslottotakeoilThetravellingsteady ismostoftenusedwhenturningdown

small diameterbarsor screwcutting long slenderbars It boltsonto the front of the cross slide in line with the chuck and

travelsalongwhenthecrossslideismovedalongthelathebedWhen turning the travelling steady can either be set to thediameterofthebarbeforeturningandtoleadthetooloritcanbesettothefinisheddiameterrequiredandtofollowthetoolNormallythefingersaresetto leadtheturningtoolbut if thebarisroughforexampleifitisdentedorrustyitisbetterforthefingerstotrailtheturningtoolIfscrewcuttingthetravellingsteadyshould lead the toolso that itdoesnotdeflectorwearduetoaburrbeingthrownupbythescrewcuttingtoolSteadies will not be used very often but they are

indispensableontheoccasionswhentheyareneeded

Travellingsteadywithleadingfingers

Travellingsteadywithtrailingfingers

MAKINGASIMPLEFORMTOOL

Youmay often need to produce a particular shape such as aradiusonacomponentTheeasiestmethodtodothisiswithaformtoolAsanexamplewewillmakeasimpleformtooltocutahalfcircleonabarofbrassForaradiusof3mmforexampleweneedtoproducea formtoolusinga6mmdiameterdrillorreamFormaterialwewillusegaugeplateahighcarbonsteelthatcomesintheformofagroundflatbarApieceabout5mmthick and10mmwide is needed although the size is not thatimportantaslongasthegaugeplateisthickenoughtoabsorbanyturningstressesIdeallyweneedataperedreamerthatwillproduce a 6mm diameter hole somewhere along its lengthalthough you could use a parallel 6mm reamer a slot drill orendmillorevenastandardtwistdrillDrill a hole through the gauge plate and open up to 6mm

diameterAim togetagoodsurface finishon thesidesof thehole Hacksaw and file half the hole away to leave the shaperequired on the finish turned component Now we need to

harden the tool although ifweare justdoingacomponentortwoinbrasswecouldprobablygetawaywithouthardeningitHardeningissimpleenoughheattheworkingendofthetool

toredstopheatingandletthegaugeplaterestforacoupleofminutesThiswillgive thegaugeplateachance tochange itsinternalstructureReheattoredandquenchinatubofwaterThisshouldhardenthetoolAlthoughabitbrittle itshouldbefine for making a few components Stone the top of the tooluntil thecuttingedge issharp Ifnecessaryyoucanpolishtheinside of the radius that is going to do the cutting There areseveralmethodsyoucanuse includingapieceofwetanddrypaperaroundabitofbaraverysmallgrindingwheelcalledamounted point or a bit of round bar with fine valve grindingcompoundonitWhicheveryouuseaimforapolishedfinishasthe finish on the turned component is directly related to thefinish on the form tool You canmakeall sorts of simple formtools with gauge plate a typical example being a facing toolwitha30-degreechamfertofaceandchamfernuts

CopytemplatereadytouseMetal

MachiningfromaTemplate

MachiningfromaTemplate

YoucanmachineaprofilefromasimpletemplateThetemplatecanbecutfromgaugeplatewithafileormachinedbutitdoesnot need to be hardened The template could be used tomachinea large radius suchasa smokeboxdoor Inuse thetemplateismountedonablockonthelathebedandthecrossslide is kept in contact with the template by being pushedagainstthetemplatewithaballracefixedtothecrossslideInthenextchapterwewillbelookingatdrillingandreaming

9DrillingandReaming

ThischapterexplainshowtousedrillsandreamersinthelatheTherearemanydifferenttypesofdrillsandreamersTheyareessentialtomakingcomponentsinthelatheWewilllookatthevarioustypesandhowtochoosethespeedsandfeedsforusingthem

Thisdrillchuckrequiresachuckkey

TYPESOFDRILL

Drills are normally held either in the tailstock if they have aMorsetaperor inadrillchuckiftheyhaveaparallelshankA

drillchuckismountedonaMorsetapershankthatisusuallythelargestMorsetaperthatthetailstockwilltakeThelargestsizeof drill that will normally fit a drill chuck is frac12in (13mm) indiameter although larger chucks are available at a cost Thesmallest sizeofdrill thatafrac12in (13mm)drill chuckwill take isusually about 116in (15mm) This is because the larger drillchuck is incapableofclosingdownenoughto take thesmallersizesofdrillThismeanswewillprobablyneedtwodrillchucksoneforlargerdrillsandoneforsmallerdrills

Hand-tighteningdrillchuck

TherearetwomaintypesofdrillchuckOneistightenedbyusinga chuckkeywhichhasa small bevelgearbuilt on to itthatmates with the outer sleeve of the drill chuck itself Theother type is hand tightenedwhere the outer chuck sleeve isknurledtotightenthedrillthesleeveisturnedbyhandLargerdrillsabovefrac12in(13mm)usuallyhaveaNo1orNo2

MorsetapershankYoucangetMorsetapersleevestoconvertalargeMorsetoasmallerMorsetaperYoucanalsogetasmallMorsetolargeMorsetaperconverteraswell

Drillwithataperedshank

Some larger drills are also available with parallel shanksTheyaremadewithasteppeddownfrac12inparallelshankandarecalledblacksmithrsquosdrills

Blacksmithrsquosdrill

Themostusefuldrills in theworkshopcomeassetsofhighspeedsteeljobberdrillsinacaseThemostpopularsetcovers1mmto6mm increasingby01mmstepsAnotheruseful setcoversfrom6mmto10mmalsoincreasingby01mmstepsIfyouareintomodelengineeringasetofnumberdrillsfromNo1toNo60istoberecommended

Asetofmetricdrillscovering1ndash6mm

Drills are also available in different lengths Stub drills areshorter than standard jobber drills Several lengths of longseries drills are also available ranging from one and a halftimesthelengthofajobberdrilluptoseveraltimesthelength

Differentlengthsofdrills

Mostdrillshavetwoflutesbutcoredrillsarealsotobehadwith three four or evenmore flutes As their name suggeststhese are usually used for drilling out cored holes in castings

CoredrillsarenotnormallycapableofstartinganewholebutareusedforopeningupexistingholesAstandarddrillusuallyhasanincludedangleof118degrees

Stub drills and cobalt drills often have a 135 to 140 degreeangle for use on hardermaterials such as stainless steel andaircraftsteelsBack rakeondrills is oftenground radially Another typeof

pointhoweverhasfourfacetstothepointFour-facetdrillsaremuch better at starting a hole than a standard jobber drillwhich tends towanderunless followingacentrepoporcentredrill Four-facet drills also require less pressure to drill a holesincethepointisthinnerthanastandarddrillandtheyarefareasier to sharpen accurately by hand than standard jobberdrillsDormerdoarangeoffour-facetdrillscalledA002withatitaniumnitridecoating(TiN)andafour-facetpoint

Three-flutecoredrill

DormerA002four-facetdrillpoint

To drill an accurate sized hole requires two ormore stepsfirst youdrill the hole undersize (by perhapsfrac12mm) then youfollowthroughwithasizedrillThechancesaretheseconddrillwillcutdeadtosizeasitisonlycuttingasmallamountfromthediameter Obviously if you are drilling a large hole moreintermediatestepsmayberequiredSpeedsfordrillingarethesameasthosegivenforturninginthetableinChapter3

Setofcentredrills

REAMERS

There are several types of reamers available for use inworkshops again with either Morse taper or parallel shanksSomehavesizeparallelshankstheshankbeingthesamesizeas the reamer while others are availablewith shanks smallerthanthereamedsizeThereisalsothewaistedreamerwheretheshankisthesamesizeasthereamerthemiddleissmaller(waisted)andthecuttingendistheholesizeYoucanalsogetadjustablereamerswheretheendisexpandedbytheuseofascrewinthecuttingendofthereamer

Handreamerthefrontparthasaslighttaper

Straightshankmachinereamer

Waistedshankmachinereamer

Morsetapershankmachinereamer

Parallelreamersaredividedintotwotypesparallelmachinereamerswhere thecuttingdiameter is thesameallalong theream and hand reamers where the cutting end is slightlysmallerandtapersuptothefulldiameterWhen drilling a hole for reaming it is advisable to use the

two-holemethodfordrillingYouaremore likelytogetagoodsize hole prior to reaming For small reamers up to 04in(10mm) leave about 0012in (03mm) for the reamer toremoveForreamersuptofrac34in(19mm)leave0016in(04mm)and over frac12in (13mm) leave 0020in (05mm) For reamingspeedsuseabouta third toahalfof thedrillingspeed for thesamediameterFeedsshouldbefrom0002to0004in(0025ndash005mm)per toothper revMultiply the feedper toothby thenumberofteethtogivethefeedperrevolutionItisbesttouseneatcuttingoilformostmaterialsexceptfor

aluminiumforwhichparaffinshouldbeusedandplasticwhichrequirescompressedairorplainwaterYoushouldnotuseoilasacuttinglubricantforanytypeofplasticasitcanattackandordegradetheplastic

10BoringToolsandBoringHeads

Thischaptershowsyouhowtoboreholesinthelathewiththeworkheldinachuckmountedonthefaceplateorfixedtothelathecrossslide

TypicalHSSboringbar

DIFFERENTTYPESOFBORINGBARS

BoringaholetosizeisoneofthemostexactingjobsyoucandoinalatheItisrelativelyeasytoturnashafttofitaholebutitis much harder to bore an accurate hole to fit a shaft Ifpossibleyoushouldboretheholebeforeturningtheshaft

YouarelikelytocomeacrossHSSboringbarsorinsertedtipboringbarsBothhavetheirusesTheHSStoolisidealformostgeneralhole-boringjobsbuttheinsertedtiptoolisfarsuperiorfor materials such as cast iron The boring bar should be aslargeasyoucangetintotheholewhilestillallowingswarftoberemovedTheboringbarshouldonlyprotrudefarenoughtoenableitto

go completely through the bore Any more protrusion than isnecessarymay result in chatter or a dig in in the bore Thefront clearance on the boring bar tip should be as small aspossiblewithoutrubbingasstrengthisimportantBoringcanbeusedtofinishaholetosizeorsimplytotruea

holeupafterdrillingandpriortoreaming It isbesttoruntheboringtoolthroughtheholeusingafinefeedtothecarriageifyouhave the feedoptiononyour latheThe final finishingcutshouldbeputthroughtwoorthreetimesatthesamesettingtoeliminateanyspringinthetoolworkorlatheIftheholehasanintermittentcutthroughitsuchasacrossholetheholeisbestboredtosizeIt ispossible toborequite smallholes if youhave the right

tool Commercial lsquosmall holersquo boring tools are very expensivebut Ibuythemsecond-handwhenever Iseethemso Iusuallyhave a stock It is easy if time consuming to grind up smallboringbarsbuttheyareveryusefulespeciallywhenyouneedtotrueupasmallholepriortotappingorreamingEndmillsandslotdrillsmakeusefulboringtoolsAs longas

yougetthecuttingedgeoncentreheighttheywillboreaswellasaproperboringbarespeciallyinaluminiumYoucanmakesimplehome-madeboringtoolsbydrillingand

reamingaholetotakeaHSStoolbitintoasteelshankIdeallythe shank should be made of high tensile material or silversteelThetoolbitshouldbesecuredwithahightensilesocket-headedgrub screwor similar The tool bit caneitherprotrudefromthesideoftheboringbarforthroughholesorprotrudeatthe frontof theshankat45degrees ifyouareboringablindholeRoundboringbarscaneitherbeclampedintotheVeegroove

foundinsometoolholdersorheldinasplitsquareshankEithermethodissuitableespeciallyastheshankcanbeslidinoroutofthetoolholdertominimizeprotrusionSpeciallyshapedtoolbitscanbeusedtoundercuttheendof

the borewhen it needs to be screwcut and canrsquot be cut rightthrough Inserted HSS boring bars can also be ground up forundercuttingbeforescrewcuttingThereareseveralmethodsofcheckingaboreforaccuracyIf

youhavetoboretheholetofitanexistingcomponentperhapsaballraceyoucanuse theexistingcomponentasagaugeorturnupagaugeRoughout theborewithina few thouof thefinishedsize taking twoor threespringcutsUsea telescopicgaugeapairofcalliperswithamicrometeroradigitalverniertomeasuretheholeBorethestartoftheholebynomorethanonethouata timedonotgoright throughtheboreTest thefrontoftheboreifthegaugedoesnotgointotheborerunthetool right throughunderpower feedBoreout the frontof theholebyanotherthouchecktheboreandrepeatuntilthegaugejustgoesintothestartoftheholeFinishtheboreatthesamesetting checking that the gauge just enters Take a couple ofspringcutstoensuretheboreisparallelYoushouldnowhaveanaccuratelysizedholeThe trick to boring is to finish with very fine cuts Many

engineersdonotrecommendfinecutsbutIhaveneverhadaproblemaslongasthetoolissharp

Asetoftelescopicgaugesforcheckingaboreusedinconjunctionwithamicrometer

Checkingaborewithahome-madegaugeTheleadinisonethousmallerthantheborerequired

USINGABORINGHEADINTHELATHE

AnothermethodofboringacomponentinthelatheistoboltitdowntothecrossslideWhentheworkpieceisbolteddownandtheholeposition is linedupwith theheadstock youcanboretheholeintheworkpieceinseveralwaysFirst however you might need to put a hole into the

workpiece to clear the centre of the hole out of theway Youcandothisbyusingadrillinathree-orfour-jawchuck(smallerdrillscouldbeusedinadrillchuck)Startwithasmalldrillandworkupalmosttothefinishedsizeoftheholetobebored

Boringaholereadyforreaming

Toboretheholethefirstoptionistoholdaboringbarinthethree-jaw chuck This is a good basic method of boring aworkpieceonthecrossslideTheonlyawkwardbitisadjustingtheboringbarsothatasizeholeisboredThisisusuallydonebyanadjustingscrewpressingontothebackofthetipoppositethe cutting edge The tip itself is usually clamped by a grubscrewthroughthesideoftheboringbarHoweveryoucanuseaboringbarthatisafewthouundertherequiredsizeandfinishoffwithareamerA similar way that is easier to adjust is to use the same

boringbar in the independent four-jawchuckThen insteadofadjusting the tip in the boring bar you can adjust the entireboringbar inthefour-jawchuckThisasyoucanimaginewillbealoteasierthantryingtoadjustthetipintheboringbarThethirdmethodofboringworkonthecrossslideistousea

properboringheadThis iseasy toadjustas it isdesigned forthisverypurposeFinallyyoucouldusea lsquobetweencentresrsquoboringbarwhich

isheldbetweentheheadstockandtailstockcentresThisistheonly option when you are doing a long bore such as a largecylindercastingforalocomotiveortractionengine

Boringtheholeusingthefour-jawchuckmethod

Usingtheboringheadinthelathemandrel

Unlike when you are facing and boring a component in achuck you will not be able to face across the front of thecomponent (Boring heads with the ability to face across theworkareavailablebutareunlikelytobefoundintheamateurrsquosworkshop) Thismeans you will have to face across the workwith a flycutter in order to keep the face true with the boreFlycutters are available quite cheaply or you couldmake yourownandholditinthefour-jawchuck

Aflycuttersuitableforfacingthefrontofacomponentthathaspreviouslybeenboredonthe

crossslide

11KnurlingRadiusTurningandProductionMethods

This chapter explains how to use knurling tools and radiusturningtoolsaswellasusingbasicproductionmethods

KNURLING

Knurlingistheprocessofformingorimpressingapatternonapiece of metal often for the purpose of making a grip for apieceofequipmentsuchasaknobBothstraightanddiamondknurlscanbeproduceddependingonthetypeofknurlyouareusing Diamond knurling is usually done with two knurlingwheelsalthoughsingle-wheeldiamondknurlsareavailableKnurls are also available in fine medium and coarse sizes

although the size is relative fromdifferentmakers The speedfor knurling is usually about half of the turning speed for thesame diameter bar Normal knurling is of the male patternwheretheknurlingconsistsofraisedpyramidsFemaleknurlingismuchrarerandconsistsofdepressedpyramidsThere are threemain types of knurling tool but only two of

these are found in the average workshop The first type ofknurling tool is the so-called lsquocutrsquo knurling toolwhichactuallycutsaknurlratherthanpressestheknurlintotheworkThisisaspecialized tool more often used in industry and is veryexpensivesoitisnotfoundinmanyhomeworkshops

lsquoBumprsquoKnurling

The most common knurl is the single-or double-wheel knurlsometimes called a lsquobumprsquo knurling tool The wheels aremountedat the frontof the tool This typeof knurl is pressedintotheworkbyusingthecrossslideandcanproduceagoodqualityknurlHowever itdoesputveryheavypressureonthemandrelandlathebearings

Acommerciallyavailablestraddleknurlingtool

StraddleKnurling

Thebest typeofknurl foroccasionaluse is thestraddleknurlwhich has two knurling wheels that completely straddle theworkpieceThistypeofknurldoesnotputastrainonthelathebearings and so is preferred bymost lathe users (Two-wheelknurlingtoolsareavailablethatresemblestraddleknurlingtoolsbut they donrsquot open up to take anything more than smalldiameters relying on pressure at the side of the job like alsquobumprsquoknurl)To set the straddle knurl up wind the tool against a bit of

plateheldontothesideofthebarRemovetheplateandmovethetoolinbythethicknessoftheplatehalftheknurldiameterandhalfthebardiameterThiswillputthetoolontothecentrelineofthebar

Settingtheknurlingtool

In use set the knurling wheels to the centre as describedabove wind the knurls onto the outside diameter of the barwindtheknurlawayfromthebarandmovetheknurlingwheelsclosertogetherbytwicethedepthoftheknurlpatternSwitchthelatheonandwindthetoolbackontothecentrelineandthetool should start to form the knurl You can now traverse theknurlingtoolalongtheworkpieceto formtheknurl remembertousecuttingoilNote that theknurlsshouldhavechamferedsidesifyouaretraversingalongtheworkpieceYouneedtogodeepenoughsotheknurlisfullyformedbut

notsodeepastodeformtheknurlBecausetheknurlstraddlestheworktheknurlsstartoff independentlyandmaynotbe inalignment around the diameter Once you start moving theknurlingtoolbackwardsandforwardsalongtheworkhoweverthetoolshouldlineitselfupThismeansyoumayhavetoturndownorpartoffthebarwhereyoustartedtheknurlIfyougotoodeepespeciallyinaluminiumthewholedepth

ofknurlcouldgetdestroyedandevendropoff theparentbarThis is called flakingKnurling isnotadifficultprocessa littlepracticewillsoonhaveyouknurlinglikeaprofessionalengineer

Anaccomplishedbitofknurling

AformtoolcuttingaballTheinsetviewshowstheformtoolandafinishedball

RADIUSTURNING

Sometimesweneedtoformanexternalradiusontheendofabit of bar perhaps for a ball-shaped handle We can use asimple lathe attachment to do this Basically the attachment

consists of a short turning tool mounted onto a U-shapedcomponent that is arranged to pivot on another U-shapedcomponentheldinthelathetoolpostBy pivoting the attachment back and forth a radiuswill be

generatedForatrueradiusthepivotpointshouldbesetonthecentrelineofthebarTheradiusgeneratedwilldependonhowfarthetoolbitissetbackfromthecentrelineoftheworkpieceTosetthetoolupwindtheattachmentuptoaplateheldto

the sideof thebar youareworkingon remove theplate andwindinthewidthoftheplatehalfthewidthofthebarandthewidthofthefixturetothecentrelineofthepinThiswillputthepivotonthecentrelineThenyoucansetthetooltotheoutsidediameterofthebarThiswillproduceaballthesamediameterasthebarTo turnan internaldiameteruse the samemethodbut the

turning tool will need to pass through the centre of the pivotand out the other side You will be limited to shallowdepressionsratherthanlargesemicirclesbutthistechniquecanstillbeusefulonoccasionThealternativemethodof formingaball iswithaball form

tool

Astopbarblockforthecarriagestop

PRODUCTIONMETHODS

PRODUCTIONMETHODS

Foreaseofproductionthefirstthingyouneedtouseisabedstop (see Chapter 5) The chances are that you will need tomakeyourownTheoneIuseisveryversatileandconsistsofablockmountedatthefrontofthelatheheadstocktogetherwitharodtoactasthestopDependinguponwhatyouaredoingitmaybeusefultohave

morethanonestopbareachwithitsownseparatestopblockInusethebarisinsertedintothemainblockasfarasthestopblock(if fitted)andlockedinplaceThefirststopbarcouldbeusedto facetheworkpieceandthesecond(shorterbar)couldbe used to turn along the diameter while a third bar couldpositionthepartingofftoolAnalternativeadditiontothestopbarcouldbeawasher(orwashers)ofknownthicknessplacingthewasher(orwashers)onthebarwillextendthestoppositionbythethicknessofthewashersusedAusefultipistostampanumberonthestopblockssothat

eachone isnumberedYoucouldalso stamp the thicknessonthewasherssoyoudonrsquothavetokeepmeasuringthemandjustpickthemupinthecorrectorderItsavesalittletimeandhelpsavoiderrorsThe whole point about using a stop is the consistency of

positionwhichistransferredtotheaccuracyofthecomponentit gives Once you have learnt to use a stop youwill wonderhowyoumanagedwithoutitEvenforone-offcomponentsitwillsaveyoutimeForatypicalone-offsteppedshaftsetthestopsotheturning

tooljustfacesthebarandfaceoffMove the top slide along for the length of the turned step

requiredTurnthestepYounowhaveastepontheendofthebarofaknownlengthNofiddlingnomeasuringndashyouknowitiscorrectUsing the bed stop offers a simple way of doing repeat

turning of lengths and diameters in the lathe Stops are notlimited to production methods they are very useful formachiningone-offsaswell

A single stop bar will serve for much of the work you aredoingbutsometimesyouneedmorethanonestopTheanswerhereistousemorethanonestopbarinconjunctionwithastopblockEachbarhasitsownstopblockthatcanbetightenedupThenyoucaninterchangethestopbarsandeachbarcanbesettotherequiredlengthbyusingavernierorruleYoujustsetthetwostopblockstothedifferencerequiredandlockthestopbarintheholderasnormalWhenyouneedmorethanoneofeachitemitisveryeasyto

save time in theworkshop once the lathe is set up you canmake several items in quick succession A typical example ofthis type of production is a simple spacer Set a facing andchamferingtoolinonetoolholderapartingofftoolinanothertoolholderandadrillinthetailstockchuckThefacingtoolandparting off tool are in fixed positions to each other so it is asimplematter of drilling thehole facingoffwithone tool andparting off with the other As long as the gap between thepartingofftoolandthefacingtoolremainsconstantthespacerswill remain at the samewidth each time youmachine one ofthemTheeasywaytosetthethicknessofthewasheristofaceoff

theendofthebarbringthepartingofftooluptothefinishedface and lock the cross slide Wind the parting off tool backslightly so you can move the bar forward in the chuckMeasuring with the vernier calliperrsquos depth rod from therighthandfaceofthepartingofftoolbringthebaroutslightlylonger than is needed for the washer thickness Using thetailstock chuck drill the hole using a centre drill for the firstwashertoensurethedrill runstrueNowsetthefacingtool inpositionfaceoffthewasherandpartofffromthebarMeasurethe washer and adjust the facing tool either way so that thethicknessof thewasher iscorrectPull thebar fromthechuckslightlyfurtherthanthefacingtoolsothateachwashercanbefaced to lengthYoucanmakeasmanywashersasyouneedall of the same thickness The same applies to nuts and anyothercomponentthatneedstobeasetlengthIfmakingboltsor screws theprinciple is thesamebutyou

willneed to turndown thediameter tobe threadedThis timethedifferencebetweenthepartingofftoolandtheturningtoolisthethicknessoftheheadInordertofacetolengthhoweverawasher of a known sizemust be inserted between the stopblockandthecrossslideThiswasherwillbethelengthoftheturneddownportionofthecomponentIfyouwanttomakeabatchofcomponentsbutdonrsquotwantto

keepmovingorchangingtoolsyoucanmachinethebatchonestepata timedoingoneoperationoneachcomponentbeforedoing the next operation on all the components Repeat thisuntil the complete batch ends up as completed componentsYou have the added advantage that the components willprobablyallbethesameshapeandsizesomethingthatisnotalwayspossiblewhenmachiningeachcomponentindividuallyTo make a batch of components such as washers to the

samethicknessisquitesimpleSetupapartingtooltopartoffthe components and set up a facing tool to face thecomponentsThedifferenceinpositionbetweenthefacingtooland the parting toolwill be the thickness of thewashers Youcanadjustthethicknessofthewasherbymovingthefacingtoolbackwardsor forwardswith the topslide toadjust it The rearpartingofftooldoesnotmoveotherthantopartoffthewasher

Makingwasherstothesamelengthusingfixedpositiontools

TAILSTOCKTURRET

AnotherusefulaccessoryisthetailstockturretThisisarotatingheadthatisusuallysetbackatanangleItfitsintothetailstockof the lathe and has multiple stations to take different toolsoftenitwilltakefourfiveorsixtoolsThebenefitofthisisthatitcanhaveabarendstopacentredrilladrillacountersinkatapandadieoranycombinationthereofallsetupreadytousein sequence The tools normally fit into holes bored into theturretToavoidtoolsstickingouttoofar it isbesttousestubdrillsinsertedintoroundbarsthatfitintotheturret

Anindexingturretthatfitsdirectlyintothetailstockofthelathe

YoucaneitherdrillandtaptheroundbarsoruseLoctite tosecure the drill in the round bar You can also buy roundadaptorswithaJacobschucktapermachinedontheendtotakechucksAnothermethodoffittingchucksistodrillandtaptheround bar to take chucks with threaded extensions ThesechuckscanoftenberetrievedfrombrokenBlackampDeckertypedrillsDieholderscanslideonapieceofroundrodintheturretFor

smaller diameter threads you can stop the die from rotatingusing your hand There is no need to reverse the lathe whenthreading just stop it and spin the die off by hand the samegoes for taps For larger taps and dies you can use a shorttommybartostoprotationbutmakesurethatthetommybarpositionisclosertotheworkthantheendofanyofthedrillsorthetommybarwillsnapthedrillsifyouletgoofitorifthetapordiejamsupYoucanalsomakeorbuyarunningcentretofitintotheturrettosaveremovingitwhenyouneedtousealathecentreOnlydothiswithsmallorlightworknotheavybarsorfor largecutsWhenused inconjunctionwithagoodbedstop

system a tailstock turret becomes a very versatile productionfacilityTheturretcanbemademoreversatilebyfittingalever-feed

tailstockattachmentoracapstan-style feedattachmenttothetailstockturretEitheroftheseattachmentswillmaketheturretveryfastinoperation

Anindexingturretsetupwithastopandacentredrill

Standardlever-feedtailstock

SECONDOPERATIONWORK

SECONDOPERATIONWORK

Sometimes it is necessary to do second operation work on apart-machinedcomponentUsually thiswillbeon theoppositeend to the one already turned There are two main ways ofholding theworkpiece in the correct position for furtherworkthechuckbackstopandsoftchuckjawsThechuckbackstopisquitesimpletomakeItconsistsofa

draw-incolletapieceofplainbarforthestopabitofthreadedbar a nut and a top hat collar The collet goes into the lathemandrelandisdrawninbythethreadedbarThethreadedbargoesthroughthemandrelandislockedinplacebythenutandthe tophatcollarat the left-handendThe tophatcollar is toprotecttheendofthemandrelThestopbarfitsthecolletandispositionedsothattheworkislocatedattherightdepthinthechuckThismeansthateachcomponentput intothechuckupagainstthebackstopwillalwaysbeheldinthesameposition

Capstan-stylelever-feedtailstock

Adraw-inbackstop

Softjawswithhexagonsadded

The secondmethod is to hold the component in soft jawswhich are bored out to hold the component (see Chapter 5)ThismeansthecomponentshouldrundeadtrueandeachonewillbeheldinthesamepositionreadytobemachinedSoft jaws tend to be used for larger components while the

backstop ismore likely tobeused forbarworkYoucanboltextension pieces to soft jaws to hold larger diameters orextensions can be machined to make a nest to take largercomponentsWhensoft jawsarewornoutandfaceddowntoo

lowforfurtheruseyoucanboltapieceofhexagonbartoeachjawtogivethemanewleaseoflifeIfyouhaveabatchofthreadedcomponentstofinishonthe

second end you can screw them into a bit of bar held in thechuck If theyarehexagonbolts just tightenup lightlywithaspanneriftheyareroundheadandtheheadwillbemachinedlateryoucouldtightenanduntightenthemwithapairofpliersThe more production work you do the more varied the

methods you will learn and the quicker you will makecomponentstoahighstandardofaccuracyA sensitive drilling attachment can be very useful when

drillingwith tiny drills The feed is by hand which gives it itssensitivity The attachment can also be used for small tapswherethetravelisfairlyshort

Machiningscrewheadsbyholdingthescrewinathreadedmandrel

Asensitivedrillingattachmentthatfitsintothe

tailstockchuck

ThisVeeattachmentisusedforcrossdrillingandcanbeusedintheheadstockorthetailstockofthelathedependingonthelengthofthebartobecrossdrilled

ThisisarevolvingtaperforthetailstockIfyoufitadrillchucktoityoucanuseitasarunningsupportforsmallbarwhereacentreisnotpermissible

12TapsDiesandScrewcutting

Thischaptershowshowtousetapsanddiestocutinternalandexternal threads in the lathe Italsoexplainshowyoucansetupasimplegeartrainandcutascrewthreadwiththehelpofascrewcuttingdialindicator

Atypicaldie

CUTTINGTHREADS

Threadcuttingeither internalorexternal isan importantpartoflearningtousealatheThepurposeofathreadisusuallysothatyouareabletoholdpartstogetheralthoughotherusesforthreadssuchasleadscrewsandfeedscrewsformachinetoolsareoftencalledfor

Safetyhasalreadybeencoveredindepth(seeChapter2)butafewextrawordsonsafetywhenthreadcuttingarecalledforWhen tapping a hole or threading a bar from the tailstock atailstocktapordieholderisoftenusedForthesmallerthreadstheholdershaveaknurledbodyandrotationcanbestoppedbysimplyholdingthebodyoftheholderinyourhandAslongasyoukeepyourhandawayfromthechuckandany

sharp lathe tools on the cross slide you should be fine (ifpossible remove either the tool holder or the tool itself )Providedthereisnothingtocatchorsquashyourhandonyoucan hold the knurled tap or die holder in your handwhile thelathe is running slowly under power and releasing the holderwhen the full length of the thread is cut or the pressurebecomes too great for you to stop the rotation (By slowly Imeaninveryslowbackgear)For largerthreadshoweveratommybarwilloftenneedto

beusedtostopthetapordieholderfromrotatingWhenusingthe tommy bar to prevent rotation do not under anycircumstances use the lathe under power Instead switch themachinerightoffandunplugit ifpossibleTurnthetapordieholdingthetommybarwiththerighthandandstopthechuckfromrotatingwiththelefthandThere are already many published charts providing thread

data covering such factors as tapping hole sizes minimummaximum and effective diameters as well as pitches andthreadsperinchIwillnotbeprovidingthemherebutwishtopoint out that tapping size drills can vary with the materialbeingcutWhenIamtappingsmallsizes instainlesssteel forexampleIusuallydrillthehole0004in(01mm)largerthanthefigurestated in thechartThisway Iam less likely tobreakatapinthehole

HSSorCarbonSteel

TapsanddiesareusuallymadefromcarbonsteelorHSSHSStapsanddiestendtoremainsharpformuchlongerthancarbonsteeltapsbutcarbonsteelisusuallycheaperNewcarbonsteel

tapsanddieswillprobablybefineforsmallerholesandsoftermaterials but wherever possible HSS should be your firstchoice Second-hand taps and dies are sometimes availablefromtoolshopsoroneBaybutinmyexperiencetheyareoftenbluntandnotworthbotheringwith

Lubricants

Whether tapping threading with a die or screwcutting it isnormallyessentialtousealubricantevenonbrassForbrassaluminium and bronze kerosene (paraffin) or white spirit isgenerallyusedandcanwithadvantagehaveasmallamountofcuttingoiladdedFor steel and stainless steel amodernpaste-based tapping

compound or cutting oil should be used This can also beappliedtocopperthismetalcanbestickybuttakeiteasyandall should gowell I also use paste or cutting oil on cast ironAlthoughmostrecommendationsaretocutcastirondryIhavefoundalubricanttobeveryhelpful

Screwthreadpitchgauge

ThreadGauges

When following a published design you will probably use thethread sizes as recommended by the designer If you are

making a thread to match an existing thread however youneedtofigureoutwhattheexistingthreadisThisiseasiesttodoonanexternalthreadIfyouhaveonlythenuttrytofindaboltthatwillfititandusethattocheckthethreadIfyoucanrsquotfindamatchingboltandtheholeinthenutisbigenoughyoucouldtrypressingabitofplasticineintotheinternalthreadandmeasuringthatTomeasuretheexternalthreadweneedtodeterminethree

thingsusingathreadpitchgauge theoutsidediameterof thethread the pitch of the thread and the thread angle Thesethree checks will probably be sufficient to decide what thethreadactuallyisBritish threads such as British Standard Fine and British

Standard Whitworth and also the Model Engineer threadsystemhaveanangleof55degreesAmerican threads such as UNF (Unified Fine) UNC (Unified

Coarse) UNEF (Unified Extra Fine) ANF (American NationalFine)ANC(AmericanNationalCoarse)are60degreesasisISOmetricUnusually theBritishStandardCycle thread is also60degreesThe other thread youmight come across is the BA (British

Association)threadThishasathreadangleof47frac12degreesandismetricbasedThelargestBAthreadis0BAwhichhasa6mmdiameterwith a 1mmpitch TheBA series godown to 22BAbutinpracticeyouareunlikelytocomeacrossanythingsmallerthanabout14BA

TAPS

TappingistheprocessofcuttinganinternalthreadwithatapFirst a hole is centre drilled and drilled in the workpiece Irecommend that you give the top of the hole a 90-degreecountersinktogivealead-intothetapandalsotostopthetapfromthrowingupaburrontothefaceofthework

Setofhandtaps

TypesofTap

The many types of tap can be divided into hand taps andmachinetapsHandtapsarenormallyheldinatapwrenchbutcan be held in the lathersquos tailstock chuck or a purpose-madetailstocktapholder

Close-upofahandsecondtap

WhentappingbyhandstartthetapuntilitstartstobiteandgiveitanextraturnorsoReversethedirectionofthetapforaturn to break the chip Continue forward for a couple of turnsand then reverseasbeforeContinue todepthor through theworkpiece by continually tapping a couple of turns reversingandcontinuingforwardThisshouldclearthechipsandpreventthetapfrombreakingIfthetapgetshardtoturntakeitrightoutoftheholetoclearanyswarfaddsomemorelubricantandcontinuetappingA set of hand taps will normally comprise a taper tap a

secondtapandaplugtapUsuallyyouwillstartaholewithataper tap This is a tap where the outside of the thread isreducedtowardsthepointbygrindingitonataperThistypeoftap can be used to start the hole but if the hole goes rightthrough the work it may be possible to screw the tap rightthroughtheholesoformingafullthreadrightthroughIfthetapertapistooshortorifyouaretappingablindhole

youneedtofollowthetapertapwiththesecondtapwhichhasmuch lessofa taper In fact itonlytapersrightat thestartofthetapTheplugtapisfinallyusedusuallytofinishoffablindhole

Theplugtaphasnotaperonitjustashortlead-inontheendBetween the three you should be able to tap themajority ofholesintheworkshopWhentappingblindholesitisbesttoworkoutthedepthand

fromtherethenumberofturnsneededforthetaptoreachthebottomoftheholeAsanexamplesaytheholeis9mmdeeptothepointThe tapenters2mminto theholebeforestarting tocutSo9mmless2mmgives7mmThepitchofthetapis05mm7mmdividedby05equals14sothenumberofturnstothebottomoftheholeis14Inpractice12or13turnswillbethemaximumneededWhen tapping blind holes make sure that all swarf is

removedfromthebottomoftheholebeforestartingtotap

Selectionoftapholders

HoldingTaps

TherearetwomaintypesoftapwrenchthehandtapwrenchwhichisdesignedtobeheldwithbothhandsandtheTeetypetapwrenchwhichoncestartedcanoftenbeusedone-handedTapsusuallyhaveeitheracentreholedrilledintheshankor

theshankisgroundtoapointThismeanswecansupportthetapfromthetailstockeitherbyusingalathecentreorbyabitofbarinthetailstockchuckwithafemalecentreinitTeetypetapwrenchesoftenhaveafemalecentreintheendandcanbesupported on a running centreWhen the tap is supported bythe tailstock at one end and the hole in theworkpiece at the

otheritmustbeinlinewiththeholeintheworkpiece

Machinetap

MachineTaps

Themaintwotypesofmachinetaparethespiralpointandthespiral flute The spiral point pushes swarf downwards throughthe hole while the spiral flute pulls the swarf out of the holeSpiralflutetapsaremuchweakerthanspiralpointtapsandintheory should not be used for tapping by hand However inpractice you can often get away with hand tapping using aspiralpointtapifyouareverycarefulIneithercasethetapisdesigned for continuous rotation swarf being automaticallycleared so the regular reversal as with a hand tap is notnecessaryIf you are careful you can probably get away with using a

hand tap under power but only do this with a hand-held tapholderwhereyoucanquicklyletgoifthetapstartstostickYou can also getmachine taps thatwill cut a thread under

powerbyscrewingthroughthejobwithoutstopping

Spiralflutetap

SpeedsforTapping

Tappingspeedsshouldbe low lowbackgearspeedshouldbefineWhenyouhavetappedtheholetodepthorrightthroughtheworkpiecestopthelatheandspinthetapoutbyhandThiswillbequickerthanreversingthelathe

ThreadingfromtheTailstock

For small taps you can use the sensitive drilling attachment(seeChapter11)orifthetapislargeryoucoulduseaslidingtapholderThiscanbeassimpleasachuckmountedonataperat one endwith a parallel hole through the chuck shank ThechuckthenslidesonabarheldinthemaintailstockchuckForlargetapsyoucanuseatommybartostopthetapholderfromturningbutthetommybarshouldnotbesolongastofoulthelathebedoranyotherpartofthemachineifyouhavetoletgoInfactitisfarsaferifyoudonotusethetommybartothreadunderpower

DIES

Dies also come in carbon steel andHSS versions The outsidediameterofadieoftenvarieswiththesizeofthethreadbeingcutalthoughthediameterwillbetooneofasetstandardDiesusually have themakerrsquos name and the thread details on thefrontof thedieThis is theside that ispresented to theworkThediewill havea short lead-in if this isnot requiredon thefinishedthreadyoucanreversethedieanditwillcleanuptoashoulder

SlidingtapholderSlidingdieholdersarealsoavailable

When cutting a thread especially a small one it pays tomaketheinitiallengthofthreadlongerthanthatrequiredThisissoyouhaveabitat thefronttoplaywithtogetthethreadright Then you can part off the excess length leaving a goodthreadoftherequiredlengthDies are usually split so you can adjust them to cut a size

threadIdeallyyoushouldhaveadieholderforeachdiesoyoucansetthedietocutsizewithouthavingtoresetiteverytimeyouchangethedieThedieshouldbesetsothatitcutsasizethreadinonepassDie nuts are often hexagonal in shape They are used to

cleanupanexistingthreadthat isdamagednot tocutanewthreadfromscratchFor each thread you are going to cut you should make a

home-madegaugetappedwithyourowntapWhenyoucutthethreadanditfitsthisgaugeyoushouldthenhaveagoodbutnottightorloosethreadYoushoulduseatailstockdieholderwithaslidingbodywhen

threadingfromthetailstockasthiswillholdthedietruetothethreadIdeally the tailstock die holder should be knurled and also

haveatommybarholeforeaseofuseThe speed for threading with a die in the lathe should be

quitelowamaximumof60rpmshouldbefineformostjobs

SCREWCUTTINGATHREAD

Whilecuttingathreadwithtapsanddiesisperfectlyadequatefor most applications the ability to cut an accurate screwthreadbyusingthelatheisaveryusefulfacilitytohaveIfthethread is large or non-standard taps and dies may not beavailable or they may be so expensive as to be out of thequestionforuseintheamateurrsquosworkshopVariouspitchesofthreadcanbecutbythesimpleexpedient

of changing the configuration of the change gears or alteringtheleversonthescrewcuttinggearboxifoneisfittedWewillconcentrate on a lathe with change gears if you have ascrewcutting gearbox please refer to the manufacturerrsquoshandbookMost lathes that youwill comeacross are likely to have an

imperialpitch leadscrewThiswillbeapitchofsomany teethper inch (TPI) Typically this will be 4 or 8 TPI although otherpitchesareavailableForourexamplewewillbeusingalathewithan8TPI leadscrewandasetofchangewheelscomprisingthefollowingnumbersofteeth2times202530353840455055606570and75

SETTINGUPTHECHANGEGEARS

Letrsquostakeatypicalthreadpitchof20TPIForeveryturnofthemandrel the leadscrew needs to move forward 120in Thismeans we have to set the change gears so the mandrel toleadscrewturnratio iscorrect Inpracticethemandrelgear islikely tobe20 teethand this is unlikely to change nomatterwhat thread we are cutting This means we will change theleadscrew gear which has to have the correct ratio to themandrelTheTPIwewishtocutis20usingaleadscrewwithapitchof

8TPI20dividedby8givesusaratioof251Thismeansthatthe mandrel gear needs to rotate at 25 times the leadscrewgearAsthemandrelhas20teeththeleadscrewgearneedstobe25times20teethwhichisa50toothgearInpracticea20toothgearanda50toothgearmaybetoosmalltotransferthedrive from the mandrel to the leadscrew and intermediategear(s)willneedtobeusedThese gears are called idler gears and they can have any

number of teeth Youmay think these idler gears change theratio of the mandrel to the leadscrew but they do not Theysimply transfer the drive from the mandrel gear to theleadscrew and the ratio stays the same This concept can behardtograspsoIwilltrytoexplainitsimplySay the mandrel gear does one turn This makes the idler

gearorgearsmoveexactly20teethandthisinturnmovestheleadscrewgearexactly20teethAsyoucanseetheratiodoesnotaltertheleadscrewgearmoves20teethforevery20teeththemandrelgearmovesandtheratiostaysthesameThistypeofset-upisknownasasimplegeartrain

Simplegeartrain

Compoundgeartrain

Letuslookatanothercommonthreadpitch32TPITheratioofleadscrewtoTPIis41(8times4=32)Sotheleadscrewgearneeds to be themandrel gear 20 teeth times 4 = 80 teethLookingattheavailablegearswedonrsquothavean80toothgearThismeanswewillhavetouseadifferentmethodtogetour41ratioWithamandrelgearof20teethwecouldusea40toothto

give us a ratio of 21 We are now halfway there but needanotherpairofgearswitha21ratioWedohavea30anda60

toothgearsothiswouldgiveusoursecond21ratioWecouldnot set these gears up as in the previous example howeversince the two intermediate gears would just act as idlers andtheratiowouldbe2150percentoutfromwhatisrequiredWhatwewouldhavetodoismountthe40toothandthe30

tooth gears on the same spindle so they rotate at the samespeedaseachother(The20toothgearmustdrivethe40toothgearandthe30toothgearmustdrivethe60toothgearinthisorder)Thiswouldgiveusthecorrect41ratiothatweneedAswehavemountedtwogearsononespindlethisisknownasasinglecompoundgeartrainDependingonyourlatheyoumayneedanidlergearbetweenthe30toothgearandthe60toothgearAgainthiswillnotalterthegearratiosYou can also have double compoundgear trainswhere two

lots of gears are mounted together on two spindles This istaking us into complicated territory however and I will referreaders to the screwcutting chart provided for their particularlathe Ifyour lathedoesnotcomewithascrewcuttingchartasearchon the Internet should findone that you candownloadandprintoutThemost likely application of double compound gear trains

would be to cutmetric threads with an imperial leadscrew orimperialthreadsover60TPII have tried to keep this explanation of setting up

screwcutting gears simple and the maths to a minimum Theexplanationgiventogetherwiththescrewcuttingchartforyourlatheshouldbemorethansufficienttogetyougoing

ExternalscrewthreadtoolmadefromaCoventry

diechaser

CUTTINGTHETHREAD

The speed for screwcutting should be about mid-back gear ifyouhaveitpreferablysomewherearound30ndash40rpmatmostTherearetwomainmethodsofscrewcuttinginthelatheThe

firstoneinvolvesthetopslidesetparalleltotheworkandintheothermethodthetopslideissetonanangletothework

Externalsinglepointscrewthreadtoolsettinggauge

Cuttinga20TPIThreadwiththeTopSlideParallel

For a 20 TPI Whitworth thread the pitch is 0050in and thethreaddepthisaconstant064ofthepitchsothethreaddepthis 0050 times 064 = 0032in This is the depth the cross slideshouldbewoundinWhilethedepthofthreadis0032inyoualsoneedtomove

the top slide forwardat eachpass Fora standardVee threadthisneedstobehalfthein-feedofthescrewcuttingtoolsoyoumovethecrossslideinby0010inandmovethetopslidealongbyhalfthis0005in

Cuttingascrewthreadwiththetopslidesetparalleltothelathe

Cuttingascrewthreadwiththetopslidesetatanangletothelathe

Theendresulta20TPIfinishedthreadbeforetidyinguptheendandundercutting

Cuttinga20TPIThreadwiththeTopSlideatanAngle

This angle will vary according to the thread being cut but itshouldbeabout1degree less thanhalf the includedangleofthethreadforaWhitworththreadof55degreesforexampletheangleshouldbehalfof55degreesminus1degreegiving265degreesNotethattheangleistakenwiththetopslidesetat90degreestotheworkWiththetopslidehandlefacingyou(at90degreestohowit isnormallyused)rotatethetopslidethe required number of degrees (265) to the right Beginnersoften rotate the top slide 265 degrees to the left from thenormalpositionwhichwouldgivean included threadangleof127degreesThisisclearlywrongBecausethetopslideissetonanangleyouwillneedtofeed

thetopslideinfurtherthanifthetopslideissetparalleltothelatheYoucan findthe increaseddepthof threadbyusingthefollowingformula

c=bcosineofA

whereAistheanglecalculatedathalftheincludedthreadangleminus1degreegiving265degreesb is thedepthof thread(forWhitworththreadsthisis064timesthepitch)andcisthecalculatedangulardepthofthreadFor a 20 TPIWhitworth thread the pitch is 0050in and the

threaddepthisaconstant064ofthepitchsothethreaddepthis0050times064=0032inThecompensateddepthofthreadisthen0032individedbythecosineof265degrees=00357

UsingtheThreadCuttingIndicator

With an 8 TPI leadscrew if the thread being cut has an evennumber of threads the leadscrew can be engaged at anypositionof the threadcuttingdial indicator If the thread isanoddnumberyoushouldusethesamenumberoranyalternatenumberthatisoneorthreetwoorfourForthreadswithahalfpitch always use the same number For metric threads orpeculiar numbers do not disengage the clasp nuts withdrawthescrewcuttingtoolandreversethemotoruntilthetoolgoesback to the start If the thread is an exact multiple of theleadscrewtheclaspnutscanbeengagedatanypositionIfindoubtalwaysengageatthesamenumberoneIttakes

verylittletimetotraversetheextradistancerequiredFor leadscrews other than 8 TPI please refer to your lathe

manual

AcknowledgementsandUsefulContacts

I would like to thankMy TimeMedia Ltd (Publishers ofModelEngineer and Model Engineersrsquo Workshop) Ken Wilson TonyJeffreeandTranswavePowerCapacitorsLtdfortheuseoftheirphotographs

USEFULCONTACTS

UnitedKingdom

ArcEuroTradeLtd10ArchdaleStreetSystonLeicesterLE71NATelephone01162695693Fax01162605805EmailinformationarceurotradecoukhttpwwwarceurotradecoukSuppliersofmachinetoolsandaccessories

ChesterMachineToolsHawardenIndustrialParkHawardenChesterCH53PZTelephone01244531631EmailsaleschestermachinetoolscomhttpwwwchestermachinetoolscomSuppliersofmachinetoolsandaccessories

CowellsSmallMachineToolsLtdTendringRoadLittleBentleyColchesterEssexCO78SH

AMyfordlathedatingfromthemid-twentiethcenturyassuppliedtoGamagesaLondondepartmentstore

Introduction

The lathe is often called the King ofmachine tools It is veryversatile and can be used to make all sorts of engineeringcomponentsHenryMaudslaywhomadehis first screwcuttingand metal-working lathe in England shortly before 1800 wasone of the first engineers to incorporate the slide rest aleadscrew and change gears into one machine This made itpossibletomakeinterchangeablescrewthreadswhichinturnrevolutionizedtheproductionofmachinesandmachinetoolsThis book is for you the practising or aspiring engineer

Whether you are working in an industrial environment or ahome workshop this book will help you to acquire importantnewskillsandgiveyouinsidertipsyouwonrsquotfindelsewherePerhapsyoudonrsquothaveaknowledgeablefriendtoteachyou

or you arenrsquot able to join a club It does not matter whatprevious experience you have this book will teach you thebasics of lathe work from first principles to advanced turningtechniques You will find all you need to know within thesepagesDuringmore than thirty years in the engineering industry I

haveworkedwithmanyengineersbothbeginnersandexpertsandhavetaughtmanyyoungpeopleduringtheirfirststepsintoengineeringWorkingasaself-employedengineerIlearntquickand accurate ways of working both frommy own experienceand from other engineers Since 2008 I have edited ModelEngineer and Model Engineersrsquo Workshop the two main UKmagazines formachining in the homeworkshop and this hasgiven me an insight into what amateur (and sometimesprofessional)engineersarelookingforIhavealsobeenabletoadvisemanyamateurengineersonhowtosolvetheirworkshopproblemsorjusttogetthemstartedontherightlines

ModelEngineersrsquoWorkshopintroducedin1990isarelativenewcomertothemodelengineeringsceneItdealsmainlywithtoolsandprocessesandisnowpublishedeveryfourweeks

ModelEngineerwhichcurrentlyappearseveryfortnighthasbeenpublishedcontinuouslysince1898Itismainlyaboutmakingprecisionmodelsbutoftenincludestechniquesforturninginthelathe

I would like to pass on some of this knowledge This bookMetal Turning on the Lathe is the first of three for CrowoodPressonaspectsofworkshopengineeringitwillbefollowedbyMilling and Introduction to Workshop Tools and TechniquesEachbookwillbeacomprehensiveguideforboththeamateurandprofessionalengineerAlatheisessentialtoallbutthemostbasicofworkshopsIt

enablesyoutoproduceturnedcomponentstoahighdegreeofaccuracywiththeminimumofeffort

ThebasicMyfordmodeltheML7wasmanufacturedformanyyearsTensofthousandsarestilltobefoundingaragesfactoriesandhomeworkshopsaroundtheworldThisistheprototypeML7LatheasrebuiltbyMyfordLtd

ThelaterML7RandSuper7modelswerefittedwithaclutchasstandardThissaveswearandtearontheelectricalcomponentsandthemotorTheyalsohadmorespeedsLaterversionsoftheSuper7canbefoundwithapowercrossfeedTheillustrationshowstheprototypeSuper7latheagainithasbeenrebuilttofactorystandardsbyMyfordLtd

TheAtoZofalathe(A)Changewheelguard(B)Countershaftpulleyguard(C)Drivebeltguard(D)Countershaft(E)Belttensionlever(F)

Oiler(G)Motor(H)Tumblergearoperatinglever(I)Headstock(J)Backgearoperatinglever(K)Mandrelnose(L)Left-handleadscrewbearing(M)Leadscrew(N)Halfnutoperatinglever(O)Toolclamp(P)Topslide(Q)Crossslide(R)Saddle(S)Apron(T)Carriagehandwheel(U)Screwthreadindicator(V)Lathebed(W)Rack(X)Tailstock(Y)Tailstockhandwheel(Z)Right-handleadscrewbearing

AnearlyMyfordlatheAlthoughverybasicitcandoalotofusefulworkintheworkshopespeciallyiftimeisspentonmakingafewsimpleaccessories

This book will show you how to use the lathe safely andeffectively in your workshop but first you should ensure thatyou are familiar with the main parts of the lathe and theirterminologywhichmaybefoundonpage9Chapter1ofthisbookisaboutchoosingalathewhatsizeof

lathe to buy the different types available desirable featuresandwhetheryoushouldbuyneworsecond-handChapter 2 covers installing a lathe how to lubricate it and

maintain it in good condition and advice on general safety inyourworkshopwithparticularemphasisonhowtousea lathesafelyChapter3will lookatthematerials fromwhichcuttingtools

aremadeaswellastheirbasicshapeandgeometryThenwe

willlookatselectingsuitablespeedsandfeedsChapter 4 dealswith sharpening lathe tools andhow to set

themupinthelatheChapter 5 covers the different types of chucks how to use

themandsetworkupaccuratelyinthemChapter 6 teaches you basic turning between centres and

then introduces turning with the work mounted on the lathefaceplateChapter7isaboutholdingworkinacolletandhowyoucan

make and use several different types of mandrel forworkholdingChapter 8 explains how to turn a taper using the top slide

theuseoffixedandtravellingsteadiesandmakingaformtoolChapter9explainshowtousedrillsandreamersinthelathe

includinghowtoselectthecorrectspeedsandfeedsChapter 10 shows the different ways to bore holes in the

lathewiththeworkheldinachuckmountedonthefaceplateorheldonthecrossslideChapter 11 explains how to use knurling tools and radius

turning tools as well as making simple form tools and basicproductionmethodsChapter 12 shows you how to use taps and dies to cut

internalandexternal threads in the lathe Italsoexplainshowto set upa simplegear train and cut a screw threadwith thehelpofascrewcuttingdialindicator

1BuyingYourFirstLathe

WHATSIZEOFLATHEDOIREQUIRE

ThefirstthingtoconsiderwhenbuyingalatheisthesizeoftheworkthatyouwanttodoWhatisthelargestdiameteryouwillwanttoturnonitandwhatisthelongestlengthyouwillneedtoturnA3frac12times18in(90times457mm)lathewillallowamaximumdiameterof7in (178mm) tobe turnedover the lathebed thelatterfigureisknownastheswingInpracticethoughthisisatheoreticalmaximumas it is stillnecessary toholdandclampthe article being turned The swing over the cross slide isusuallymuchsmallertypically2in(50mm)Many lathes however aremanufacturedwith a gapbed at

the headstock end to enable short items of a large diametersuchaslocomotiveortractionenginewheelstobeturnedLathes are also sometimes available as standard and long

bed lathes The long bed lathe as the name suggests allowslongermaterial to be turned within the capacity of the latheWhen turning longermaterial the diameter will be limited bytheswingoverthecrossslideThiswillbealotsmallerthantheswingoverthebedIfbuildingamodelsuchasatractionengineoralocomotive

the deciding factor for the size of lathe is likely to be thediameterof the largestpairofwheels thatneed tobe turnedBefore deciding on the size of lathe required you shoulddetermine the size of the largest diameter and the longestlength of material that needs to be turned Another factor indeterminingwhat lathe tobuy is theavailabilityof sparesand

accessoriesisthecompanystilltradingwillitstillbetradinginthe future and are there large amounts of secondhand partsandaccessoriesavailablefromtooldealersoroneBay

Atypicalinvertertoconvert240voltssinglephaseto240volts3phase

LATHEELECTRICS

Single phase electric is where the lathe plugs into the mainssupplyinyourhouseThemotorwillhavetheusualliveneutraland earth leads Lathes supplied for factory use usually havethree phase motors and require three live wires each of adifferentphaseThinkofaphaseasan incomingwaveon theseashore three successive waves make up the three phasesneededEachphaseisthesameastheprecedingonebuttheyareoutofsyncandallpeakatadifferenttime

Aforwardreversecontrolboxforaninverter

Convertersandinverters

Youcan runsome3phasemotors fromasinglephasesupplyviaaconverteroraninverterThemotor informationplatewillusuallysay240volts440voltsif it iscapableofrunningonaninverter Inside the motor there will be changeover tags tochange the motor from 440V down to 240V Follow theconverterinverter manufacturerrsquos instructions for furtherinformation It isnotusuallyverycomplicatedto runa240V3phasemotor from an inverter and thiswill give a quieter andsmoother running motor than a single phase supply canprovide This usually requires some simple programmingexplainedintheinverterrsquosinstructionsanditusuallytakesfiveminutestogetthemotorworkingproperly

ThismotorispartoftheinverterpackageshowninthepreviousillustrationNowiringisinvolvedasthemotorleadplugsstraightintotheinverterbox

Theinverterrunsataconstantvoltagebutthespeedofthemotor will change as the frequency is raised or lowered Isuggest limitingyour inverter from full speed tohalf speed sothatthefanstillcoolsthemotorandstopsitfromoverheatingyoucanthenusethebeltstochangethemainspeedstepsasusual(Ifyoumustuseveryslowrunningitispossibletoaddaseparatefansuchasacomputercoolingfantogiveconstantairflow) Most inverter suppliers offer a forwardreverse andspeedcontrolboxthatcanbesetupinaconvenientpositiononthe machine These are well worth fitting for convenience inuse

Thisinverterisdesignedformountingonthefrontofthelathe

While inverters are designed to run only onemachine youcangetconverterstopowermorethanonemachineatatimeDependingonthesizeandpoweroutputconverterscostaboutthreetofourtimesasmuchasaninverterTherearetwomaintypesofconverterRotaryconvertersare

designedtorunmorethanonemotoratatimeThisis ideal ifyouwanttorunmorethanonemachineortwomotorsononemachineforexamplethemainmachinemotorandperhapsanauxiliary motor that drives the machinersquos coolant pump orpowerfeedsystem

Arotaryconvertercapableofpoweringmorethanone3phasemotor

ThesecondtypeisthestaticconverterwhichisdesignedtorunonemotoratatimeThereisofcoursenothingtostopyouusingthestaticconverteronmorethanonemachinebyfittingasuitablefemaleelectricalconnectortothestaticconverterandmatchingmaleconnectorstotheindividualmachinesThiswayyoucanconnectthestaticconvertertoonlyonemachineatatime

Thisstaticconverterissuitableforpoweringone3phasemotorIfyoufitasocketontheoutputhoweverdifferentindividualmachinescanbepluggedintoitoneatatime

Theelectricalloadingonrotaryorstaticconvertersmustnotexceed theirmaximumrating If indoubton the loadcapacityneeded to run your machine(s) you should consult the

manufacturerorsupplieroftheconverter

AnearthleakagetripisidealforquicklyeliminatingamotorwheretheelectricalinsulationisbreakingdownItisusefulfordetectingcertainelectricalearthingfaultsbutshouldnotbeusedasaguaranteeofelectricalsafety

Simpleelectricaltestingandsafety

Whenbuyingasmallsinglephasesecondhandlathetakewithyouanearth leakage testerof the typeused for lawnmowersandothergardentoolsIonceboughtaUnimat3lathetookithomeandpluggeditinItkeptblowingtheearthleakagetripinthefuseboxeventhoughithadworkedperfectlyatthesellerrsquoshouseIsolditonatalossbutthebuyerdidknowtherewasaproblemwiththeelectricsIt is most important that the metal parts of any lathe are

connectedtotheearthwirewhichisinturnconnectedtoearthMake sure that themotor frame is also connected toearthassome motors have dampening rubber mounts that insulatethem from themachine itself If in doubt about any aspect ofelectricalinstallationpleaseconsultaqualifiedelectrician

Acontinuousbedisidealwhenworkingwiththefaceplateorwithcollets

LATHEBED

Thelathebedisthebackboneoftheentirelatheandisthepartthat is mounted on the bench or stand There are two maintypesoflathebedtheplainbedandthegapbedTheplainbedisusuallycontinuousallthewayalongitslengthwhilethegapbedhasas itsnamesuggestsagap in thebedThis isnotaliteralgapbutasteppedsectionthatallowsbiggerdiameterstobeturnedthanyouwouldotherwisebeabletoturnonaplainbed latheThisgap isameansofmakinga lathesmaller thanwouldberequiredforaplainlatheabletoturnasimilarsizeof

componentSome continuous lathe beds have a section next to the

headstock that can be removed to increase the diameter thatcanbeturnedThisfeatureisusuallyonlyfittedtolargerlathessuchasaremostlyfoundinfactoriesSome lathes have hardened beds although most are just

plaincast ironTherearethreemaintypesofbedwayscalledshearstheplainflatbedwithsquarewaysabedwithaflattopand a 60 degree dovetail at each side and a bedwith raisedandinvertedVeewaysOnthelastofthesethetailstockusuallyrunsononesetofVeesand thecarriageonadifferent setofVees resulting in lesswear to themain slidesWidebedsarebetterandmoreaccurateasthelathecarriageislesslikelytotwistonawidebed

Close-upviewofatypicallathebedwithagapAgapbedlathehasalargerturningdiametercapacitythantheequivalentsizedcontinuousbedlathe

Someveryearly lathessuchas thosemadebyDrummondhad a round bed Although they worked well there is noadjustmentforwearinthelathebed

TheMyfordrangeoflatheshasasquareformofbed

ThistypeofbedhasaflattopwithaninvertedVeeateachsideTheVeesareusuallysetat60degreesbutcanvarywithdifferentmakers

The Unimat SL lathe was sold for many years and manysecondhandexamplesarestillavailableThismodeldiffersfrommostlathesinthatithastwosteelbarsasabedThisisnotaproblemhoweverastheUnimatisintendedonlyforverysmallandlightweightmodel-makingworkandthereistheadvantagethatthebedcanbereplacedbyfittingnewbarsWhen buying a secondhand lathe it is most important to

checktheconditionofthebedYouneedtomakesurethebedis reasonably free from dings rust and hacksaw marksHacksawmarksneartheheadstockareoftencausedbysawing

offworkwhile it isheld inthechuckdingsareusuallycausedbydroppingthechuckonthelathebedwhenscrewingitonoroffthemandrelAsimplechuckboardplacedonthebedwhilefittingorremovingthechuckwillprotectthebedItisalsoidealfor protecting the bed when filing or hacksawing work in thechuck

AlathebedwithraisedandinvertedVeesThecarriageusuallyslidesononesetofVeesandthetailstockslidesontheother

AmodernChineselathebedwithaninvertedraisedVeeThecarriageandtailstockusuallyslideonthesameVee

Wear ismost commonly found at the headstock end of thelathe as a result of machining many short components andrelatively few long ones Make sure the lathe carriage isproperlyadjustedattheheadstockandthenrunitalongasfaras you can towards the tailstock The carriage should bereasonablyfreebutnotlooseallthewayalongthebed

OldroundbedDrummondlathesarestillavailablesecondhandThisparticularexampleistreadledriven

AflatbedlathewithsquarebedwayssuchasaMyfordcanbe checked for wear on the lathe bed using amicrometer orvernierCheckovertheworkingpartofthelathebedonwhichthe carriage slides rather than the part that is not used forguidance Check both the width and the thickness of the bedwaysThetailstockshouldalsobeagoodslidingfitonanyguiding

surfaces Wear is most likely to be found on the tenon thatslidesbetween thebedwaysAworn tenoncouldprobablybereplacedbutthereisnotmuchyoucandoifthetenonguidesarewornTheonlyway to fixawornbed requiresacompletebedregrindThisislikelytobeexpensivesoitwouldbebettertolookforanunwornlatheDecentunwornlathesareouttheresincemanymodelengineersmayhaveboughtthemnewfortyorfiftyyearsagoandhardlyusedthem

TheUnimatSLisaverypopularsmalllatheItsbedconsistsoftwosteelbarsthatcanbereplacedveryeasilywithsilversteeliftheygetwornormorelikelywhentheygetrusty

Asimplewoodenchuckboardwillprotectthelathebedfromdingsandhacksawmarks

LATHEHEADSTOCK

Theheadstockisthelargecomponentmountedattheleft-handside of the lathe bed It needs to have good bearings An all-gearedheadwillalmostcertainlyhaveballorrollerraceswhilethe older type of lathe for amateurs may well have plainbearings either phosphor bronze or whitemetal These areperfectlyadequatebutyoushouldmakesurethere isnowearinthemSomelathesalsohaveamandrelthatrunsdirectly inbored holes in the cast iron headstock casting Plain bearingswillbeperfectlysatisfactoryas longasadequate lubrication isused

Close-upviewofaMyfordheadstockonanML7RNotethelargebronzebearingatthefrontTheearlierML7latheshadwhitemetalbearingsalthoughtheC7capstanhadbronzebearingsandahardenedlathespindle

Tocheck forwear in the lathersquosbearings fitachuck to themandrelandputadialtestindicatorontopofthechuckGentlytry levering the chuck up and down by using a steel bar orsimilarheldinthechuckYouarelookingforminimalmovementhereespeciallyonaheadstockfittedwithballraces

CheckingthelathebearingsforwearAnymovementupanddownindicateswearinthebearing

The mandrel is mounted in the headstock and is usuallythreaded to take a chuck or faceplate The lathersquos mandrelshould not move back and forth in the bearings If it doeshowever itwillprobablybepossibletoadjust ittocorrectanyendwise movement The mandrel should not be too stiff butshouldturneasilybyhandWhentestingalathemakesuretheheadstockbearingsare

correctlyadjustedsothatwherepossiblethereisnoplaySeta tool up take a trial cut alonga length of bar and check forchatter If you are using a correctly set tool and a suitablespeedchatterisasuresignofwornbearings

Manylatheshaveathree-orfour-stepdrivepulleyasthesecondstageofthedrivechain

POWERDRIVE

Manylatheshaveathree-orfour-steppulleyonthemandreltotake the drive from a similar pulley on the countershaft Thecountershaft is in turn driven from the motor which is oftenmounted at the back of the headstock and completes theintegral drive system that is so popular on most amateursrsquolathes

Thisparticularlathehasatwo-stepmotorpulleyandcountershaftwhichdoublestheavailablespeeds

SpeedchartonthebeltguardofaMyfordML7Rlathe

AfewlatheshaveaclutchfittedasstandardorasanoptionalextraTheclutchsaveshavingtostartandstopthemotorwhileitisrunningThishelpstostopwearandtearonthemotorandelectricalsystemAdifferenttypeofclutchsystemtheTriLevaspeedselector

wasonlyfittedtoMyfordML7orC7lathesThishasthreeleversfor setting threedifferent speedsDependingon the leveryoudepressyougetahighmediumorlowspeedIfyoupressoneof the levers downwhile another is right down the first leverwilldisengagethesecondsostoppingthemandrelfromgoinground If the lathe is switched off and all three handles aredepressed the mandrel is locked preventing rotation This isusefuliffilingorhacksawinginthelathe

TheclutchisnormallymountedinsidethelargecountershaftpulleyItisusuallyoperatedbyaleverattheright-handsideoftheheadstockattachedtoapushrodthatpassesrightthroughthecountershaft

TheMyfordTriLevaattachmentwillonlyfitML7andC7lathesandisnotsuitableforML7RorSuper7lathes

Therehasbeenatrend inrecentyearstodoawaywiththecountershaftandpulleysystemandtoreplacethemotorwithavariable speed one with an electronic controller This isacceptable except that at low revolutions it does not providethe torque that can be obtained from a countershaft systemThereisalsothedisadvantagethatthereisnowaytodrivethelatheifthecontrollercircuitboardfailswhereasyoucanjustfita new one if the belt breaks The board could of course befixed provided that a circuit diagram is available and theelectronic components can be identified Sometimes thecomponents are marked with internal house numbers ratherthan commercially recognized part numbers that can beorderedasareplacementfromacatalogueSomeboardsmighteven have the identification marks removed to make repairsalmostimpossible

ThethreadedendofalathemandrelisdesignedsothatthechuckbackplaterunstrueIfthechuckmountingfaceofthebackplateismachinedinsituthechuckshouldruntrueaswell

CHUCKMOUNTINGSYSTEMS

The threaded lathe mandrel nose is not by itself a suitablelocationforachuckorfaceplatesothenoseisusuallygivenaturned register on which to locate the chuck The chuck isscrewedrightontothemandrelovertheregisterandbuttsuptoaturnedcollartokeepthechuckrunningtrueTheothersideof the mandrel collar butts up against the main headstockbearingwhichusuallyactsasathrustfaceThemandrelisusuallyboredthroughandmachinedtotakea

MorsetapercentreforturningbetweencentresDonotputyourfingerineitherendofthemandreltocleanitwhilethelatheisrunningAneasywaytocleanthetaperintheheadstockiswithabottlebrush often sold in chemists to cleanbabiesrsquo bottlesAnalternativeisasoftfeltshotgunbrushdonotuseonemadefromwire

ThislathehasaplainregisterAccuracyreliesonthelathechuckbeingagoodfitontheregister

There are various systems of chuck mounting in useespeciallyon the larger lathesTheproblemwith thescrew-ontype with a register mentioned above is that the chuck orfaceplatecanunscrewwhenthelatheisrunninginreverseTheonly timeyoushould run this typeofmandrel in reverseveryslowly and without taking a cut is if you need to return thescrewcuttingtooltothestartofthethreadyouarecuttingAlternativespindlenosescanbeaplaindiscwitharegisterto

boltthechuckontooracamlockwherethechuckisheldontightlybyturningstudstolockthechuckontothemandrelTheplain discwith register relies on having chuckswith amatingregistertoworkproperly

AnAmericanstandardCamLockchuckmountingbackplateandCamLockchuckplatefittedtoachuckTheyareusuallyfittedtolargerindustriallathes

TheAmericanDstyleCamLocksystemeithertakesachuckor faceplate directly or it has a backplate that can have aregisterturnedonittosuittherequiredchuckAlthoughmanylathe mandrels with Cam Lock fittings have six holes thematchingchuckorfaceplateoftenhasonlythreelockingpinsThe advantage of both of the last two systems is that they

canberuninreversewithoutthechuckcomingoffthemandrel

Theleadscrewisdrivenfromthemandrelviaageartrain

SCREWCUTTINGGEARS

The left-hand end of the mandrel will often have a gearmountedonittodrivethechangewheelgearsandleadscrewThe mandrel gear usually drives a pair of gears called

tumblergearswhicharemountedona leveratthe leftoftheheadstock The direction of the leadscrew can be changed bybringingeitheroneortheotherintogearbyraisingorloweringaleverThereisusuallyacentralneutralpositionwhereneithergearisinmeshThissaveswearonthelathechangewheelsandleadscrew bearings as well as reducing noise while workingMandrelandtumblergearswillbediscussedfurtherinChapter12whenwesetupascrewcuttinggeartrain

A set of changewheels usually comprises about a dozengearsbutthiscanvarydependingonthemanufacturerThesechangewheels which take the drive from the tumbler gearsdown to the leadscrew are mounted on moveable studs toensurethegearsareinmeshwitheachotherDependingonthenumber of gears in the train the leadscrew will turn eitherclockwiseoranti-clockwiseThedirectionof the leadscrewcanbe reversed using the tumbler gears to enable right-hand orleft-handthreadstobecut

Oftentherearetumblergearsinthegeartrainthatcanreversethedirectionoftheleadscrew

YoucanusuallysetthegearstocutaveryfinepitchsothattheleadscrewactsasaselffeedwhenturningfromthesaddleIf you anticipate the need to do any screwcutting check thatthesuppliedscrewcuttinggearswilldotherangeofpitchesyourequire It has been known for certain lathes to be unable tohandle somecommonpitches a typical examplebeing26TPI(teeth per inch) A pitch of 26 TPI is often needed to repairmotorcycles and bikes made before the introduction ofmetrication

MakesurethatafullsetofchangegearsisincludedwiththelatheIfnottheyarereadilyavailablesecondhand

LEADSCREW

The leadscrew ismounted at the front of the lathe there areusuallybearings to support the leadscrewateitherendof thelathe bed It is used tomove the lathe saddle along the bedeither for a self acting feed or for screwcutting Some lathesalso have a graduated handwheel mounted at the right-handendoftheleadscrewforturningthemandrelbyhandSome of the larger lathes also have a separate feed shaft

whichisusuallyaplainroundshaftwithakeywaycutalongittodrivethesaddleusingafinefeedThissaveswearandtearontheleadscrewwhichisthenonlyusedforscrewcutting

Mostleadscrewscanhaveagraduatedhandwheelmountedontheright-handendoftheleadscrew

SCREWCUTTINGFACILITIES

Ausefulfeatureonanylatheistheabilitytocutscrewthreadsof different pitches Leadscrews come in different pitches acommon one being 8 TPI but many variations are fitted todifferent lathes including leadscrews with a metric pitch It isawkward tomachinemetricscrewswithan imperial leadscrewandviceversaSometimesmetricconversionsetsareavailablebuttheycanbehardtofindareusuallyexpensiveandrequirethe lathe to be changed over often using 127 tooth gearwheels This figure is derived from multiplying the metricequivalentof1in(254mm)byfivea127toothwheelisthusadirectconversiontoametricthreadonalathewithanimperialleadscrewA127 toothgear isusuallyvery large if itmatchesthepitchoftheremainingscrewcuttinggearsbutyoucouldusesmallergearswitha smallerDP (diametralpitch)but stillwith127 teeth Youwould also need amatching gear of say fiftyteethtogiveyoua2541ratio

Thislathehasbothaleadscrewforscrewcuttingandadriveshaftforthesaddleandcrossslidefeeds

Ascrewcuttingdialindicatorusuallymountedtotherightofthe carriage is a useful feature This is a small dial withdivisionsmarkedonitmountedonashaftTheotherendoftheshafthasagearthatmesheswiththeleadscrewandmakesthedial go roundWhen the clasp nuts are engaged the carriagemoves and as the gear moves at the same speed as thecarriagethedialstopsgoingroundWhen you engage the clasp nuts on the leadscrew the

positionwhereyouengagedependsonthepitchofthethreadbeing cut Some thread pitches allow you to engage at anydivision of the dial while others need to be engaged at aparticularpositionof thedialTheuseof thescrewcuttingdialindicator will be covered in Chapter 12 When using the finefeedyoucanengagetheclaspnutsatanymarkedpositiononthedialsoavoidingweartotheclaspnuts

AtypicalscrewthreaddialindicatorThisoneisengagedanddisengagedbylooseningtheboltandengagingthedrivegearwiththeleadscrew

LATHESADDLEANDAPRON

The saddle is thepart that slides on top of the lathebedandusually has the cross slide and top slide mounted on it Theapron ismounted to the frontof the saddleYoushouldmakesure there isnoplay in the saddle either sidewaysorupanddownandthatittravelsfreelyfromoneendofthelathebedtotheotherwithnotightspotsAtthefrontnearesttheoperatorthereisusuallyapairofclaspnuts(thesearesplitnuts)Thesecan be engaged or disengaged from the leadscrew forscrewcuttingormovingthesaddlealongwiththeleadscrewOncheaper lathes there is usually a solid nut that cannot bedisengaged

ThelathesaddleslidesalongthelathebedTheapronisboltedtothefrontofthesaddle

There is often a rack at the front of the lathe bed thatmatches upwith a handle and gears on the lathe apron Thiscan be used to move the carriage along the bed withoutwearingouttheleadscrewSomelatheshavethecarriagefeedwheel on the right but others have it on the left where hotswarfcanfallontoyourhandsThecheaperlatheshavenorackandrelyontheleadscrewtowindthecarriagebackandforth

ATee-slottedcrossslidemakesthesmalllathemoreversatile

CROSSSLIDE

On top of the carriage is the cross slidewhich canbewoundbackandforthacrossthelathebedWhenusingthecrossslideforfacingacrosstheworkthecarriageshouldbelockedtostopitmovingalongthebedLathesforamateurusearemorelikelytohaveaTee-slottedcrossslidewhilelargercommerciallathesare unlikely to have this facility The Tee-slotted cross slide isveryusefulespeciallyifyoudonrsquothaveamillingmachineYoucanboltworktothecrossslideformachiningusingacutterinthechuckorforboringworkpiecesthataretoolargetoswinginthechuckZero settingdials aredesirable for both the cross slide and

thetopslideTheyallowyoutosetthedialtozerowhichmakesiteasiertomeasuretheamountyouaretakingoffwithonecutInusewindthetooluptotheworkandtouchonsetthedialtozeroandwind the toolbackoff from theworkYounowknowwherezeroisonthetoolandcantaketherequireddepthofcut

withouthavingtoworkitout

Zerosettingdialsmaketurningandscrewcuttingtodepthveryeasy

Apairofzerosettingdialsreadytofit

LathescanbepurchasedwithimperialormetricfeedscrewsMostmodeldesignsareimperialbutmetricismakingheadwayandthismaywellbethewaytogoBewarelatheswithimperialfeedscrewsandmetricdialsTypically thesewillhavea funnynumber of handwheel divisions rather than a whole numberMostofthelathesyoumightcomeacrossareunlikelytohavea

power cross feed for facing This does notmatter as you caneasilywindthecrossslideacrossbyhandTheonlytimeIhavefound a power cross feed to be of use is when I had to faceacross a faceplate to true it up I have trued up similar sizefaceplatesbyhanditjusttookalittlelonger

Thetopslideismountedonthecrossslide

TOPSLIDE

ThetopslideismountedontopofthecrossslideThetopslideisnormallysetat90degreestothecrossslidealthoughitcanusually be swivelled around to various angles for turning ataperanangleorforscrewcuttingSomeofthecheaperlathesdonrsquothaveatopslideasstandardbutitisaveryusefulfeatureif you can get one The top slide should be able to rotateespecially for screwcutting but the top slide handlemay foulthecrossslideincertainpositionssocheckifthisisaproblemTheturningtoolisusuallymountedonthetopofthetopslideItcan either be clamped on directly usually with packing stripsunderneathorthetoolcanbemountedinatoolholdersuchasathree-orfour-waytoolpostoraquickchangetoolpostWewilllook at tool holding methods in Chapter 4 when discussingsettingupturningtools

TAILSTOCK

The component at the right-hand end of the lathe is thetailstock This usually has a handwheel to feed a drill into theworkbut leverfeedandcapstan-style feedingmechanismsarealso available You can lock the tailstock anywhere along thebed The tailstock has a barrel inside it that can bewound inandouttogivealinearmovementtodrillaholeinworkheldinthechuckThetailstockisusuallyboredtoaMorsetaperoftenof a similar size to the headstock so it can take accessoriessuchasdrillchucksmountedonaMorsetaperItcanalsotakeacentre for turningworkbetweencentres It is important thatboth the headstock and tailstock tapers are free frommarksscratchesandburrs

AlathetailstockwiththebarrelextendedNotethatitisnotusuallyaproblemifthechuckkeyisleftinthetailstockwhilenotinuse

Adjustment is usually provided between the base and themain body of the tailstock to allow for setting the tailstock inlinewith theheadstock Tailstocks canbe self ejectingwherethetool isextractedas it iswoundbackwhilesometailstockshavea throughholeandneeda tapwithabar to remove thetool Handwheel depth graduations for drill drilling to a

particularholedepthareveryusefulbutarenotoftenincludedon the cheaper lathes although industrial lathes usually havegraduatedtailstockhandwheelsThebettermakesoflathehavea lever clamping tailstock arrangement while the cheaperlathesoftenhaveaclampingspanneroranAllenscrewclamp

Allguardsshouldbefittedinplacebeforeoperatingthelathe

MACHINEGUARDS

Thedrivemotorcountershaft(iffitted)andpulleybeltsshouldallbeproperlyguarded It isveryeasy togetcaughtup inanunguardedmachineandtheconsequencescanbequitenastyThis has never happened to me but I have seen someonecaught up in a machine and it was not very nice I dorecommend that you make sure your machine guards arecorrectlyfitted

OTHERDESIRABLEFEATURES

Digitalreadoutsareusefulonalatheastheycanshowyouhowmuch to move the handwheels and how much material hasbeentakenoffTheyarequiteexpensivebutyoucan fit themyourself if youare carefulUnfortunatelymost of the cheaperversionsdislikesolubleoilorothercoolantifyougetitintothereadouthead

Adigitalreadoutsuitableformountingonalathe

Youwillneedtwoslidesoneforeachaxis

A soluble pump for cutting fluid is useful and often comesfittedasstandardonthelargerlathesHoweveratinofcuttingoilandabrushwillbegoodenoughformostworkandthatmaysuityoufine

Solubleoilpumpsandreservoirsarereadilyobtainable

Formostjobsyoucangetawaywithsomecuttingoilabowlandabrush

TheMyfordlsquoNortonrsquostylequickchangescrewcuttinggearbox

A Norton quickchange screwcutting gearbox saves time asyou donrsquot have to set up changewheel trains A gearboxhowever considerably increases the price of the averagesecondhand lathe A Myford Norton gearbox has twenty-fourpitchesandiscontrolledbytwoleversReversingtwogears inthe Myford changewheel train gives the gearbox twenty-fourfine feeds insteadof the twenty-fourscrewcuttingpitchesThegearboxhasa setofgearsarrangedasaconeBysliding thelever along and dropping themaster gear onto the cone youcanchangethegearboxratioandsothepitch

TheconegearsinsideatypicalNortonscrewcuttinggearbox(notanoriginalMyfordone)

SeveraldesignshavebeenpublishedtomakeyourownNortontypescrewcuttinggearboxThisoneisavailablefromHemingwayKits

SPINDLESPEEDS

Thespeed rangeneededona lathedependson thework it is

requiredtodoAgoodrangeofspindlespeedsisdesirablewithnoobviousgapsWithelectroniccontrolthisshouldnotbetoomuchofaproblemIdeally a back-geared lathe would be best but this means

either a good secondhand machine such as a Myford or aBoxford or alternatively one of the larger Asian-made latheswithanall-gearedheadstock

Thisbackgeararrangementisswitchedinandoutbyturningthetoggleonthepulleyandliftingaleveratthefrontofthelathe

Backgearnormallyconsistsoffourgearstwolargeonesandtwosmalloneswhichcanbeswitched inorout toreducethespeedofthelathebyaratioofusuallyabout51dependingonthe maker to enable you to turn large diameter workpiecesThis reduction is also essential on a screwcutting lathe asotherwisethemandrelwillbegoingtoofastwhilescrewcuttingandyouwonrsquotbeable tostop in the rightplaceat theendofthethreadIf buying a back-geared lathe check that both gearwheels

havealltheirteethItisamajorjobtostripdownalatheandfitnewgearwheelsassumingtheyareevenavailableassparesCheckthelatheinallgearrangeswiththelatherunningIfa

back-geared lathe or an all-geared head is noisy it could

indicatewearitwillalsobeanuisanceinyourworkshopasnoonewants to hear a noisymachine runningNoise could be amajorproblemespeciallyifyouhaveneighboursnearbyGearedheadsusuallyhaveawiderangeofspeedsthelarger

industrial lathescangoup tospeedsof2000rpmandsmallerversionsareoftenhigher

Anall-gearedheadonamodernindustrialsizelathe

On the more usual amateursrsquo lathe there is often acountershaft usually tensioned by a lever which tightens upthebeltreadyforuseThemiddlespeedofthecountershaft isusually chosen to be about one quarter of the motor speedMost small lathes have three speeds and the back geararrangement adds another three speeds giving six in all TheMyfordSuper7rangeoflatheshavefourspeedsandbackgearmaking eight speeds but there is also a double pulley on themotor countershaft section making sixteen speeds in allalthoughtheverylowestback-gearedspeedswillrarelyifeverbeusedSomeoftheolderColchesterChipmasterlatheshavewhatis

knownasaKoppVariatordriveThis isavariable speeddrivecontrolledbyadialandthesystemworkswellbuttheVariator

isveryhardtoreplaceifthedrivefails

ThissmallCowellslatheiscapableofdecentworkandatthetimeofwritingisprobablytheonlylathestillbeingmadeinBritain

MOUNTINGTHELATHE

There are three main options for mounting a lathe benchmounting portable or on a stand Ideally a makerrsquos standshouldbeusedformountingamediumto large latheandthestandisoftenanintegralpartof larger lathesAsmaller lathesuch as a Unimat or a Cowell can bemounted on a woodenchopping board or a similar small board These lathes can beputawayinacupboardafteruseThe alternative is a workbench but these are often made

from wood which can expand or contract depending on themoistureintheairWoodisnotagoodmaterialfromwhichtomakea stand for a larger latheas itwill attractmoisture andmayexpandshrinkordistortAmetalstandisabetteroptionWewilllookatinstallingthelatheinChapter2

AnArcEuroTradeC3screwcuttinglathemadebySiegThisisaverypopularentrylevellatheandmanyaccessoriesareavailable

Amedium-sizedscrewcuttinglathesuitableforgardenshedworkshops

SHOULDIBUYNEWORSECONDHAND

Beginnerssettingupaworkshopoftenaskifitisbettertobuyanew lathe or secondhand The preceding pages should have

given some guidance but there are more points to be takenintoconsideration

Alargerindustriallathewithafoot-operatedemergencycut-offswitchandbrake

BuyingNew

Thelistoflathesuppliersincludedatthebackofthisbookwereall in business at the time of writing Most will be willing todemonstratetheirrangeofmachinesattheirpremisesorwhileattendingmodelengineeringexhibitionsPaycloseattentiontomechanical noise the general paint finish and the workingslideway surfaceswhich should begroundDoes themachinehave sharpor roughedges (Handwheelsareespeciallypronetosharpedges)The main thing to consider though is the attitude of the

supplier Were they willing to talk to you and answer yourquestionseitheratanexhibitionoroverthephoneHowlongdo they take toanswer thephonewhenyou ring their servicedepartment Do they know the answer to a simple questionstraightawayordotheyhavetogetbacktoyouIsthemanual

written in English or Chinglish (translated awkwardly fromMandarinorCantonese)There are several suppliers of new lathes inmost countries

aroundtheworldbutthemajorityoflathesaremadeintheFarEastOftensupplierArsquosmachinescomefromthesamefactoryassupplierBrsquostheyarejustpaintedadifferentcolourandhavedifferentnamesandlabelsfittedAftersales service can vary greatly Usually companies that

havebeeninbusinesslongerwillofferbetteraftersalesservicebutotherpeoplersquosexperiencescanbefoundonInternetforumsoratlocalmodelengineeringclubsUsually theAsian lathesare reasonablywellmadebut they

often suffer from having plastic gears instead of metal onesOneortwocompaniessupplymetalgearsasstandardso it isworthaskingiftheirmachineshavemetalorplasticdrivegearsSome companies also offer after-market replacement metalgears

BuyingSecondhand

There aremany good quality secondhandmachines availablebut there is also a lot of worn-out rubbish If possible take aknowledgeable friend with you when purchasing a lathe Becareful when buying at online auctions such as eBay MostsellersaregenuinebutsomearenotNeverpartwiththecashuntil youhavechecked the latheover IhaveboughtoneBaywithoutproblemsbut Iamcarefulwhat IbuyandwhofromAsmall latheforacoupleofhundredpoundsisunlikelytobreakthe bank if it is a bit of a dog but a lathe that costs severalhundredpounds is adifferentmatter ThegreenMyfordML7RpicturedthroughoutthisbookwaspurchasedfromeBayItwasbrand new the motor had never been fitted and it was abargainwhencomparedwiththeretailpriceIdidpaycashoncollectionbutIwouldhavewalkedawayif ithadnotmatchedthedescriptioninanywayWhether purchasing new or secondhand check what

accessoriescomeaspartofthepackageandwhatwillneedto

bepurchasedseparatelyEssentialtoolingcanoftendoublethecost of a newmachine if it is not included in the price whilededicatedtoolingmaynotevenbeavailable forasecondhandbargainlathe

Youshouldnowhaveanideaofthesizeoflatheyouneedthefunctionofthedifferentpartsofthelatheandwhetheryouarebuying new or secondhand In Chapter 2 we will look atinstallingthelatheandsafetyintheworkshop

2InstallingtheLatheandUsingItSafely

If you are buying a new lathe completewith delivery to yourworkshopyoucangostraighttothesectiononsettingthelatheupIfyouarecollectingthelatheyourselfhoweveryoushouldpayattentiontoafewwordsonmovingit

Ifyouhaveroomtomanoeuvreanenginehoistcanbeusedtomovemachineryaroundsafely

MOVINGTHELATHE

MOVINGTHELATHE

When going to collect your lathemake sure someonewill betheretohelpyouloaditortakesomeonewithyouUnlessitisaminiaturelatheitwillbetooheavyforonepersontoliftHelpisalsoneededwhenyougetthelathehomeLiftingthelatheoutofacarcanbeharder than lifting it in It isadvisable tohavethreepeoplewhenunloading twoat theheavyheadstockendandoneliftingthelightertailstockendYoucanrentorbuyanenginehoist fora reasonablepriceand this canmakemovingthemachineeasierIf the machine is a substantial industrial type it would be

besttohireatransportcompanythatspecializes inmachineryremovals Professional machinery removers will usually haveproperlyequippedtransporttomoveheavymachinesThiswillprobablyworkoutcheaperthanattemptingtodoityourselfbutmake sure they have insurance in place in case they damagethelatheoryourpropertyYoushouldalsoensuretheyknowithas to beput in place as required in theworkshop youdonrsquotwanthalfatonofmachinerydumpedonyourdrivewithnowayofmovingitintopositionLathesareusuallytopheavywhenbeingmovedandcantip

overifyouarenotcarefulTheMyfordML7seriesforexampleoftenhasthemotorandcountershaftboltedtothebackofthelathe bed and this type of lathewill tend to tip backwards Asimple solution is to bolt two lengths of wood about 4 times 2in(100times50mm)tothelathefeetOneboltineachendwilldoifyou canrsquot drill holes in the correct position This will stop thelathe tipping backwards and also make it easier to lift IfpossibleyoushouldremovethetailstockThisisoftenaheavylumpofmetalbutitisusuallyveryeasytoslideitofftheendofthelathebedAnyotherlargeobjectsthatcanberemovedandreplacedlaterwillmakethelathelighterandeasiertomove

Twoplanksofwoodboltedtothelathefeetwilloftenturnanunmanageablemassofmetalintoaneasilyhandledmachine

Azerovoltsswitchisessentialequipmentonanymachinetool

Wearoldclotheswhenmovingyourlatheandhaveplentyofold rags to wipe off swarf and oil Lay down old blankets ordecoratorsrsquosheetsinsidethecarandasheetofthickcardboardMDForplywoodtohelpprotectthebootareawhenslidingthelatheintothecar

AsmallishlathecanoftenbefittedintoastandardhatchbackorestatecarYoumayfindhowever thatyouhavetodotwotrips one for the lathe and accessories and another for thecabinetthelathestandsonTosaveawastedjourneyIusuallytrytofitthelathecabinetinfirstIfIthenfindthatthecabinetdoesnrsquotfitIcanstillbringthelatheandtoolinghomeknowingthat Ihave tohireavan tocollect thecabinetbutalso that IhavenothadawastedjourneyIfyouhavetosplittheelectricsforexampletotakethelathe

offthecabinetdrawadiagramoftheelectricalconnectionssoyoucanrewirethelathewhenyougetithomeAdigitalcameraisalsoagoodmethodofrecordingthewiringconnectionsbutIwouldnotrelyonthecameraaloneIf the lathedoesnothaveazerovoltsswitch itwouldbea

good idea to fit one after you get the lathe home They areavailable quite cheaply andare easily fitted If in doubt aboutyourabilitytodoelectricalwiringconsultaqualifiedelectrician

Adjustablefeetareveryusefulforlevellingupthelathe

SETTINGUPTHELATHE

Somelathesusuallythelargerindustrialoneshaveanintegral

bedandcabinetThelathecanbesettotruewithjustshimmingunderthefeetorbyadjustingthefeetOther lathes may need to be mounted level and true to

ensureaccuracywhenturningSetthebenchstandas levelasyou can in both directions using a spirit level as a guide Anycheapspirit levelwilldoas longas it isaccurateYoucantesttheaccuracyofaspiritlevelbyturningitround180degreesifitisaccurateitshouldreadthesamebothwaysOnce the stand is reasonably level youcan level the lathe

ThisinvolvesjackingorshimmingupthelatheuntilitistrueinbothdirectionsIfusingawoodenbenchputmetalplatesunderthe feet tospread the loadShimoradjust the latheuntil it isreasonablylevel

Putthespiritlevelonthecabinetrsquoslongitudinalaxisandusetheadjustablefeettolevelthelathe

Insertalengthofbarinthechuckandputadialtestindicatoron top of the tailstock end of the bar Nip the headstock endmounting bolts down first and then tighten down the tailstockendboltsAdjustorshimthetailstockenduntilthereisnosignof movement on the test indicator Next 64repeat theprocedure with the dial test indicator on the front of the barAgainyouare looking fornomovementCheckbothdirectionsagainmakingsurethereisnomovementeitherhorizontallyorverticallywhenyoutightenthelathedownAdjustorshimuntil

there is no movement in either direction when the lathe isclampeddownAslongasthebedisnottwistedthelathebedshouldnowbetrue

1Insertapieceof⅛in(3mm)packingunderthespiritlevelatthetailstockendThiswillresultinarunonthedriptrayandalltheoldoilwillruntotheendofthelathemakingiteasiertocleanup

2Placethespiritlevelonthecabinetcrossaxisandusetheadjustablefeettolevelthelathe

3Putthespiritlevelonthelathecrossaxisattheheadstockendandlevelitasbestyoucan

4Putthespiritlevelonthelongitudinalaxisandlevelalongthelathe

5Testthetopofthebarthereshouldbenomovementwhenthelatheisclampeddown

6Testthefrontofthebaragainensuringthatthereisnomovementwhenthelatheisclampeddown

Alignthetailstockbyusingadialtestindicatorintheheadstock

AligningtheTailstock

NowweneedtosetthetailstockinlinewiththeheadstockDothisbyputting thedial test indicator into theheadstockchuckandtestthetailstockboreAdjustthetailstocktowardsthefrontortothebackofthebeduntilthetestindicatorreadstrueandtighten theclampscrewsA slightdifference inverticalheightwillnotbetheendoftheworlditjustmeansthereisprobablysomeweartothebaseofthetailstockcastingbutthereshouldbenovariationfromfronttobackinthehorizontalalignmentPutalongbarbetweenthecentresandtakealightcutalong

it using a fine power feed Run along the bar a couple moretimes at the same setting to remove any push offWhen youmeasure thebar it shouldmeasure the sameatbothends Ifthe bar is larger at the tailstock end you need to reduce theheightofthebedatthefrontofthetailstockslightlyIfsmalleratthetailstockendyouneedtoreducetheshimatthebackofthe tailstockend Itprobablywonrsquotneedmuchadjustmentasslightadjustmentstotheshimoradjustersatthetailstockendwillsoonbringitintoline

Usingatestbartocheckforparallelturning

LubricatingtheLathe

You should follow the manufacturerrsquos recommendations forlubrication Usually this is thin oil for the headstock oftenhydraulicoilandslidewayoil forthemovingpartsLubricationshouldbedoneregularlyIfthelatheisfittedwithasightfeedoileritshouldshowoilinitAdjustablesightfeedoilersasusedonMyfordandsimilarlathesshouldbeadjustedsothattheoildripswhen the lathe is running but does not dripmuchwhenthe lathe is stopped The slight vibration when the motor isrunningisusuallyenoughtocausetheoiltodripToomuchoilisbetterthannotenoughoilisfarcheaperthannewbearings

Atypicaldrip-feedlubricator

UseanoilgunonalltheoilnipplesYoucangetaroundthetendencyfortheoiltogoeverywhereexceptintothenipplebyputtingapieceofwritingpaperoverthenippleandthenusingthe oil gun as normal The paper will stop the oil squirtingeverywhereThemandrelbackgearalsoneedstobelubricatedWheninusethemainbackgearisrunningontheoutsideofthelathemandrelandneedstobelubricatedoftenoritwillgethotandwearChangewheels should be lubricated with oil not grease If

youusegreaseswarfwillsticktothechangewheelsandcauseunnecessarywearTo stopswarf running through themandrelanddroppingoutontothechangewheelsputawinebottlecorkor similar into the left-hand end of the mandrel This willeffectivelystopanyswarfgettingthroughtothechangewheelsOil the saddle and cross slide and also the nipples on the

tailstock Make sure oil is showing at the edge of the slidingsurfaces A squirt of oil on the cross slide and topslide feedscrew bearing is needed as well Check the manufacturerrsquosinstructions for lubricating the rest of the lathe Follow themotormakerrsquosrecommendationforlubricatingthemotorTrytoavoidusingWD40onthelatheWhileitisanexcellent

lubricantwaterdisplacerittendstodiscolourthelathebed

Useabitofpaperundertheoilguntostoptheoilsquirtingeverywhere

AvoidingtheRustFairy

Rust canplayhavocwith a lathe quickly turning thebedandother parts into a brownmess Various sizes of plastic coverssuitable forcovering lathesareoftensold foruseasbarbecuecoversinDIYstoresAplasticlathecoverwillhelptokeeprustatbaybutmoreneeds tobedoneAbagcontainingsilicagelplacedundertheplasticcoverforexamplewillabsorbexcessmoisturesilicagelcanbeboughtverycheaplyoneBay

SilicageliseasilyobtainablefromeBay

Alternatively you can buy a vapour phase inhibitor forprotecting the lathe The vapour phase inhibitor chemical issuppliedonafeltpadinsideaplasticpotThechemicalformsaprotectivelayeroneverysurfaceBecauseitisavapouritwillfind its way into every cranny and is also used for protectingtools and accessories in tool cabinets and drawers It usuallylasts for twelvemonths ifenclosedby theplasticcoverSomemachinetooldealersareabletosellsuppliesofthisproductinsmall ready to use containers rather than in industrialquantitiesAlwayscleanthelathedownafteruseswarfwillsoonrustif

leftonalatheasitwillprobablybecleanfromturningandwillnotbeprotectedbyoilTheuseofanovencookingtrayunderthe lathe bedmakes it easy to remove swarf at the end of aturning session The tray also helps to retrieve a parted offcomponentora lost screw froma tipped turning toolAnotheralternativeistocoverthelathechiptraywithnewspaperwhenyouhave finished turning remove thenewspaper screw it upandthrowitawayWhenfittingachuckorfaceplatetothelathemakesureyou

cleanthemandrelthreadtheregisterandthefaceYoushouldalso clean the mating threads the bore and the face on thechuckorfaceplateYoucancleanthethreadandboreeasilybyusing two toothbrushes bolted back to back with spacers inbetween Make sure the Morse tapers in the headstock andtailstock are cleanbefore fitting aMorse taper accessory TheMorse taper to be fitted should be free from scratches burrsandbruisesIt is good idea tomake a chuck board for usewhen fitting

chucks to a lathe or removing them This is a piece of wood(plywood will do) that sits on the lathe bed while you arescrewingthechuckonandoffThechuckboardwillprotectthelathe ifyoudrop thechuck It canalsobeused toprotect thelathebedwhenyouarehacksawingorfilinginthelatheIf you keep your lathe clean and lubricate it regularly it

shouldlastalifetime

AlargetraywillcatchmuchoftheswarfandtheholeslettheoildrainawayUsenewspapertosoakuptheexcessoil

SAFETYINTHEWORKSHOP

RememberyouareresponsibleforyourownsafetySafetyisamajorconcernintheworkshopTherearecertain

thingsyoushoulddoandobviouslythingsyoushouldnotByitsverynatureaworkshopcanbeadangerousplaceallwecandoismakeitassafeaspossiblewhilestillallowingustoworkinit

WorkingAlone

Mostofyoureadingthisbookwillprobablybeworkingaloneinasmallworkshopgarageorgardenshed IfyougethurtyoumaypossiblybeonyourownAsapriorityIsuggestyoutakeamobilephoneintotheworkshopandkeepitinyourpocketTheability to contact your family a friend or the emergencyservicesquicklycouldsaveyour lifeKeepthephoneswitchedoff while in the workshop however as it is an unnecessarydistraction

FirstAid

FirstAid

AFirstAidboxwithcontentsisanecessityandshouldincludeaneye-bathandeyewashYoushouldparticularlylearnhowtostopbloodflowingThereareplentyofwebsitesthatwilltellyouhowtodothisCheckthemoutnowbeforeyougobackintotheworkshop

ElectricalSafety

Checkforearthcontinuitywhilethemachineisunpluggedwithavoltohmmeterfromtheearthpinonthethreepinplugtothemetalpartofthelathe(somepaintmayhavetoberemovedforareadingtotakeplace)Youshouldgetareadingofzeroohmsorabeep if themeterhasacontinuity rangeYoushouldalsobe sure that the electrical sockets on the wall are correctlyearthedIfindoubtconsultacompetentelectricianLightingandelectricheatingshouldbeonaseparatecircuit

tothemachinessoyouwillstillhavelightifthemachinestripoutPlugasmalllightintothemachinecircuitsoyouhavesomelight if the lighting circuit trips out When I go on holiday Ialwaysturnoffthefusetripsforthelightinginordertomakeitmore difficult for intruders to move about quickly Leave thehouse alarm and smoke detectors on (The house alarmmayactivateeighthoursafter theelectricity is turnedoffwhenthebatteryexpires)

Adigitalmultimeterisveryusefulinthehomeworkshop

BeAware

Bementally alert while using the lathe Avoid operations thatmightputyourhandsatriskofenteringthemovingpartsofthelathe Do not operate any lathe while under the influence ofdrugs alcohol or prescription medication that may causedrowsinessorotherwiseaffectyourability to control the lathesafelyDonotattempttoworkonalatheandtalkatthesametimeIfyouhavetotalktosomeoneswitchoffthelathebeforedoingso

KeepItClean

TheareaaroundalatheshouldbekeptfreeofobstructionsThefloorshouldbecleananddrywithanyoilorotherspillscleanedup immediately The lathe should be kept clean and tidyMachinedangerareasshouldbemarkedontheworkshopfloorand observed Workbenches placed near a lathe should be

strongandequippedwithanon-slipsafetysurfacetostoptoolsor other items rolling onto the floor a rubber car mat willsufficeA rubberdoormat on the floorwill allow swarf todropthrough in order to save you getting swarf embedded in thesolesofyourshoes

Asuitablefloormatwillallowswarftodropthroughandhelpkeepyourfeetwarminwinter

LearntoUsetheLathe

Donotuseany lathebeforeyouare familiarwith thecontrolsandareawareofthedifferentwaysofstoppingitThismaybea clutch an onoff switch a No Volts release switch or anemergency stop button I strongly advise fitting a No VoltsreleaseswitchifyourlathedoesnothaveoneAswellasbeingusefulforstoppingthelatheinanemergencyitwillpreventthelathefromstartingupbyitselfafterapowercutIfyouarenotcomfortableworkingwith electrical equipment get a qualifiedelectriciantofittheswitchforyou

StaywiththeLathe

Nevereverwalkawayevenforamomentwhilethelatheyouare using is switched on Switch it off if you are leaving itunattended and only leave the lathe after it has come to a

completestopNeverleavealatheinanunsafeconditionMakesure that you have not left the chuck key in the chuck Thechancesarethatifyouarehalfwaythroughsettingupthelathewhen you return you will forget what you have or have notdoneIfindoubtleaveabignoticeremindingyourselftocheckthatthelatheissafebeforecontinuing

Donotleavethechuckkeyinthechuck

SwitchOffwhenAdjustingtheLathe

Shut off the power supply to the motor before starting anyoperationsrequiringaccesstothelathesuchaschangingtoolsmeasuring work mounting or removing accessories changingspeed and setting up change gears The lathemust be safelystopped Just zeroing a variable-speed drive is not safelystoppingitusethezerovoltsswitchtoswitchthepoweroffaswell

CheckbeforeStartingtheLathe

AlwaysrotateyourworkpiecebyhandtomakesureitclearsthetoolrestsaddleandbedDoublechecktomakesureyourworkis securely clamped in the chuck or between centres beforestartingthelatheBecertainthattheworkpieceturnsfreelyand

isfirmlymountedThespeedofthelathemustbecheckedbeforeturningiton

When turning irregular shapes start the lathe on a low speedandincreasethespeedbyapulleystepeachtimeIfthelatheisbouncingabout lowerthespeedandorbalancethework Ifthe work vibrates stop the lathe and check the reason ThechancesarethatyouarerunningthelathetoofastMeasuringequipment toolingandworkpiecesshouldnotbe

leftona latheastheycanvibrateoff intomovingcomponentsand be thrown around the room Check for loose items on alathebeforeuse

UsetheLatheGuards

NewlatheswillbefittedwithguardsoverthemotorshaftdrivebeltandspindlepulleysTheseguardsshouldalwaysbeinplacebefore using the lathe Any other moving parts should beguardedtopreventanythingfallingontothemovingpartsAlthoughguardsareoften removedbymachinistsprovided

they are constructed from clearmaterials and open and closeeasily theyaddsafetywithout interferingwith theworkbeingdone Guards will at the same time deflect swarf and anycoolantthatisbeingusedGuardsfittedtothelatheshouldnotbe removed while it is in use They should be made fromsuitablematerialandnothavesharpedgesTheyshouldnotberemovedforadjustmentandlubricationofthelatheunlessthisis unavoidable Lathemanufacturers donrsquot usually supply chipguards soaddingoneshouldbeconsideredChipguardswithmagnetic bases are available although they can attract steelswarftothemagnetPutthebaseintoaplasticbagtoaidswarfremoval

UseEyeProtection

Lathes can throw sharp metal chips considerable distancesespecially at high cutting speeds Apart from deep cuts thechipsmay leave the tool red hot cause skin burns and even

burnholes in clothing Youmust use safety goggles or propersafetyspectacleswhileintheworkshopAlwayswearindustrialqualitysafetyglassesfittedwithsideshieldsSpectacleswithoutsafety lenses are not adequate eye protection When theglasses get dirty do not wipe them off as they will becomescratchedWashthemoffunderthetapinstead

TakeCarewhenRemovingSwarf

Do not attempt to remove chips or turnings with your handsAlwaysswitchoff the lathefirstandeitherpull theswarfawaywithalargemetalhookorliftitoffusingapairofglovesIftheswarf is tangled around the lathe untangle it with a pair ofpliersandnotaglovedhandasitwillcutstraightthroughtheglovesandintoyourhandUseadustpanandbrushtoremovesmall chips and swarf from the swarf tray ndash never use yourhandsWhenswarfbecomesstringyandbuildsuponthetoolortoolpostturnoffthelathebeforeremovingit

AvoidLooseClothing

IfyouarenotwearingoverallswearshortsleevedshirtsorrolllongshirtsleevesabovetheelbowsLoosesleevescancatchonrotatingworkandquicklypullyourhandorarmintothe latheObviously though keep your arms protected if hot swarf isflyingaroundSwarf can get inside protective clothing especially collars

(useaclothespegtokeepyourcollartight)pocketsandshoesTostopthesleevesofanoverallcatchingsewelastic intothecuffsorwrapacoupleofthickelasticbandsaroundthecuffstostopthesleevesgettingcaughtupUnder no circumstances wear a necktie when operating a

latheProtectiveglovesshouldneverbewornwhileoperatingalathe Protective gloves may be worn when swarf is beingremovedbuttheymustberemovedbeforeswitchingthelathebackon

UseSturdyFootwear

WearsteeltoecapsafetybootstheyarenotexpensiveandwillhelptoprotectyourfeetfrominjuryifyoudropaheavyobjectonthemThelsquotrainerrsquoversionisparticularlycomfortableDonotallow stringy swarf to fall on the floor as youwill get cuts onyouranklesandmayeventripoverit

AvoidJewellery

Do not wear wristwatches rings or jewellery when in theworkshop as it could catch on a rotating part of the lathe orworkpieceThisalsoapplieswhenmovingalatheintooroutoftheworkshopsincetheycouldcatchona falling lathe IfyourotherhalfcomplainsthatyouhavetakenoffyourweddingringexplainthatyouwouldnrsquotbeabletowearitagainifyourfingerismissingduetoanaccidentLonghairshouldbetiedbackasyoucouldbepulledintothelatheifitgetscaughtintherotatingwork

LiftingintheWorkshop

Back injuries can be caused by incorrect lifting practices It isimportant to bend your legs when lifting rather than bendingyour back A hoist or engine lift should be used to lift heavyitems A stool in theworkshopwill take the pressure off yourlegs and will provide a welcome break after you have beenstoodatthelatheforawhile

Self-ignitingMaterials

If you machine titanium or magnesium which can ignite andburn vigorously keep the accumulation of turnings to aminimum If thematerialdoescatch firedonrsquotusewaterorawater-based coolant as an extinguisher since it will makematters much worse Before starting to machine titanium ormagnesiumfillalargebucketwithdrysandcoveritandkeep

it by the lathe The sand will smother the flames veryeffectivelyYoucouldalsobuyoneofthespecialfireretardantsusedinindustryBeware also of grinding aluminium on the bench grinder

Aluminium and steel filings are the ingredients of Thermite apowerful explosive that can also burn If you grind aluminiumandthenchangeovertogrindingsteeltheredhotsparksareliable to set the steelaluminium mix on fire This is a verydangerous combination ofmaterials and should be avoided atallcosts

SafetywithBarStock

Bar stock should be contained within the headstock and notallowed to protrude from the rear of themandrel I once sawsomeone switchona lathewhenabrassbarwas stickingoutfrom the back of the headstock by about two feet With thelathe running at 2000rpm the bar whichwas aboutfrac34in (19mm) in diameter was bent at right angles and caused theheavy lathe which weighed 1280kg to jump about Luckilysomeone managed to switch the lathe off before any majordamageoccurredItwasnottheoperatorhehadrunwellawayandwasnowheretobeseen

SomeFinalWordsonSafety

Wherever possible the machine height should be adjusted tosuittheuserWearestillusingfifty-year-oldmachinesbutfiftyyearsagothenationwasshorterTheworkplaceshouldbeprovidedwithuniformlightingthat

gives an adequate level of illumination Individual machinelightsarebestThe lathemust be set to operate at the speeds and feeds

recommended for thespecificmetalbeingturned If themetalrotatestooslowlyortooquicklyorthefeed istooslowortoofastaccidentsarelikelytooccurThe area directly in front of and behind the workpiece is

known as the lsquofiring zonersquo or the lsquored zonersquo This is where apiece of work is likely to go as it leaves the lathe Make it ahabit to keep clear of this zone when you turn the lathe onLearnwhere theNoVolts switch is as youmightneed to turnthelatheoffquicklyByfollowingalltheaboveadviceyoushouldnowbeableto

worksafelyfullyawareofanysafetyproblemsthatmightariseAtthispointyounowknowhowtoinstallthelathelookafter

itclean itandmaintain it InChapter3wewill lookatcuttingtoolsandexaminehowtoselectcuttingspeedsandfeeds

Thisbarisstickingouttoofarfromthebackofthelathe

3CuttingToolPrinciplesFeedsandSpeeds

The first part of this chapter will look at the materials fromwhichcuttingtoolsaremadeaswellastheirbasicshapeandgeometryWewill thenconsider selectingsuitablespeedsandfeeds

MAINTYPESOFTURNINGTOOLS

There are three main types of turning tool used in modernworkshops HSS (high speed steel) tools carbide brazed-ontoolsandinsertedtiptoolsAllhavetheirusesintheworkshopandformost jobsthere isnopreferenceforonetypeovertheothersTherearealsocarbonsteeltoolbitsalthoughinpracticetheyarejustaboutobsoleteCarbonsteeltoolscanbemadeinthe homeworkshop but apart frombeing used tomake formtools(seeChapter11)thereaderisunlikelytousethismaterialfortools

Ageneral-purposeHSSturningtoolsuitableformildsteel

HSSTOOLS

HSStoolscanbepurchasedsinglyorinsetsalreadygroundtothecorrectshapeIt ischeaperhowevertopurchasethemassquare tool blanks in various sizes ready for you to grind toshapeThecompleteready-groundsetswillprobablycomewithseveralshapesincludedthatyouwillneveruseIfyoucanbuyafewready-groundtoolscheaplytheywillbeofuseasguidestoseehowtosharpenyourownHSStoolblanksHSS form tools from industry are often available second-

handTheseareespeciallygroundtomachineacomplex formall in one go You can often find some that are ground to asuitable shape to form the end of a threaded componentincludingtheundercut

HSSformturningtools

Brazed-onCarbideTools

Brazed-on carbide-tipped tools are quite useful especially forfacing and boring cast iron but they really need a diamond-facedgrindingwheeltokeepthemsharpCarbidetipsandtoolscomeinvarioussizesandhardnesstosuitindividualmaterialscarbidetoolsforsteelwilloftenbepaintedbluethoseforcastiron are painted red and those for stainless steel are paintedyellowThecolourindicatesthesuitabilityofthetoolforcertainmaterials

Brazed-oncarbide-tippedtoolscomeinvariousgradesshapesandsizes

InsertedTipTools

InsertedcarbidetiptoolsareveryusefulbuttheyarenotcheapThe tipsarenotusually sharpenedafterwearingout you justthrow the tip away and fit a new one Most modern carbide

inserts however do have more than one cutting facesometimestheyhavetwoandoccasionallyfourormorecuttingedgesareavailableYoucanevengetformturningtoolswheretheinsertisroundandcanberotatedafull360degrees

Theleft-handtoolisblueindicatingitisformildsteelwhiletheright-handtoolisredindicatingitisforturningcastiron

Some diamond-shaped tips can be used in different toolholders two edges are used in one tool holder and the othertwoedgesareusedinanothertoolholdersoyougettwicethelifepertipInserted tip tools are available for internal and external

screwcuttingwherethetipsareheldat thecorrecthelixangleofthethreadinthetoolholderThedrawbackisthecostofthetipsandeachsizeofthreadusuallyneedsitsownsizeoftip

Aninsertedtipcarbideturningtool

Carbidegroovingtools

InsertedtipgroovingtoolsareidealformachininggroovesforOrings and circlips Theyare available inmany standardwidthsandcanoftenbeusedasparting-offtoolsforsmallerdiametersOneof themostusefulgrooving tools forsmallersizegroovesandpartingoffistheMiniThinsystemassoldbyMSCIndustrialSupplyCo

TheMiniThintoolholderisidealforgroovingandalsoforpartingoffsmalldiametersTheshankissostrongcomparedwiththecutbeingtakenthatusinganoverhangasshownisquite

safe

Coatingstoreducetoolwear

Tipsarealsoavailablewith various coatings that improve toollifeThemostcommoncoatingistitaniumnitride(TiN)whichisgold in colour Other coatings that offer slightly better wearresistancearetitaniumcarbonnitride(TiCN)whichisbluegreyincolourandtitaniumaluminiumnitride(TiAlN)whichisvioletbronzeReady-groundHSScuttingtoolssuchasdrillstapsandreamers are also available with these coatings but once yousharpenthecutterthecoatingisgoneTipped toolsneedadeeper cut ahigher feedandahigher

speed than HSS tools Thismeans that the lathe needs to bestrongrigidandhaveamplepowertodrivethe lathemandrelwhen taking a heavy cut this rules out using tipped tools onlathessmallerthanabout2in(50mm)centreheightSmaller tools are made to fit the Unimat and similar small

lathesbutthesemachinesjustdonrsquothavethepowerneededtodrivethemAtbesttakingacutwillstopthelatheatworstthetoolwillchip

Insertedtiptypes

Inserted tip tools come in many shapes and sizes Some tipshapes and sizes are made to an international standard andothers are to the makerrsquos own standards Wherever possibleuse ISOstandardtoolsas thetipswillbe interchangeablewiththosefromothermanufacturersandwillprobablybecheaperaswell The ANSI system commonly used in the USA is notcompatiblewiththeISOsystemusedintherestoftheworldIfyour lathe ispowerfulenoughyoucantakeadvantageof

insertedtippartingoffbladesThesearemounted inaspecialtoolblockandthebladecanbeslidinoroutdependingonthediameteryouarepartingoffThebladecarriesan inserted tipspecially designed for parting off There are three types of tipavailablesquare-endedtipstipsthatareangledtotheleftand

tips that are angled to the right Square tips are used forgeneral parting off tips angled to the left are usedwhen youdonrsquotwanttoleaveapiponthebackendoftheworkandtipsangledtotherightareusedwhenyouwantacleanfaceonthefrontoftheworkThe parting off blade is oftenmounted upside down at the

backofthe lathecrossslideTheactionofpartingofftendstolift the whole cross slide slightly and forces the cross slidetightly into thematching dovetail whichmakes itmuchmorerigidIfthepartingofftooldigsinwhileinthebacktoolpostthetool tends to lift and push away from the work whereas in afronttoolpostthetooltendstodiginandpullintothework

Simplifieddiagramofpartingofftoolangles(A)straightpartingtool(B)angledtotheleft(C)angledtotheright

POWERREQUIREMENTS

Whenturningmildsteelorstainlesssteelwithanycarbidetoolthe machine horse power required is considerably more thanthat required forordinaryHSStoolsThe twomain reasons forthisarethatcarbidetoolsoftenhaveanegativerakeangleonthecuttingedgeasthistypeofedgelastsmuchlongerthanapositiveangle especially for intermittent cuts andbecause in

industrial use carbide tips are called on to remove largerquantitiesofmetalathigherspeedsandfeedsFor guidance on using tipped tools in the small workshop

wheretimeisnotasimportantasinanindustrialenvironmentIwould recommendusing twice the speedused fornormalHSStools and a fine feed of about 0002in (005mm) per rev as astarting point This can be adjusted up or downdepending ontheresultsThemaindifferencebetweenHSStoolsandcarbidetippedtools(eitherbrazed-onorinsertedtip)isthehorsepowerrequirementofthemachineinuse

Thispartingofftoolismountedatthebackofthelatheinaspecialbacktoolholder

SELECTINGTHECORRECTSPEEDSFORDIFFERENTMATERIALS

Overmanyyears through trialanderror cuttingspeedshavebeendeterminedthatgiveanoptimumtoollifebalancedwithadecent surface finish These speeds are normally quoted inlsquosurfacespeedinfeetperminutersquoSpeeds and feeds used on industrial machines where the

primary tools will have inserted tips will be a lot higher than

thoseusedinthesmallworkshopwhereHSStoolsarethenormThe accompanying table gives an idea of the speeds that

shouldbeused forvariouscommon typesofmaterial likely tobefoundintheworkshopThespeedslistedshouldbesuitableforbothturninganddrillinginthelatheForreaminguseabout25percentoftherecommendedspeedsThe table is a guide only and it is likely that the machine

speedsavailablewillnotbeexactlythoserequiredandyoumayhavetoresorttolsquonearenoughisgoodenoughrsquoSetthelathetothe nearest speed lower than indicated in the table for thediameterandmaterialbeingcutThiswillbefineforHSStoolsDouble the recommended HSS speed for carbide tools For

parting off use about 30 per cent of the recommended HSSspeed For form tools use about 50 per cent of therecommended speed for the initial cuts and then engage thecorresponding back gear (just switch to back gear leaving thebelts on the same pulley) and gently tap the handle until itreachesthefinishedsizeandallowittofinishthecutbyitselfYou may have to adjust the speed down if you get a lot ofchatter

Forturningcastironuseacarbide-tippedtoolrunningattheHSSspeedtoremovetheskinYoucanthenfinishtheturningwithaHSSsteeltoolifyouwishPlease remember if doing any work that might be

unbalancedstartoffslowlyandincreasethespeedabeltstepatatime

THEACTIONOFCUTTINGTOOLS

Basicallya lathe tool isawedge that is forced into theendofthe rotating bar to remove metal As long as the tool is fedforwardwhilethelatheisrotatingmaterialwillberemovedA typical right-hand turning tool has a cutting angle of 90

degreeslessthesideclearancelessthesiderakeThecuttingangle for this example is 90ndash10ndash10= 70 degrees This is theangle that is wedged into the work to remove the materialSoftermaterialswillhaveasmallercuttinganglewhilehardermaterials will have a larger cutting angle Tool angles varydependingonthetypeofmetalbeingturnedToolsforturningsofter metals usually have higher rake angles than thosedesigned for harder metals since a turning tool will normallyholditsedgeforlongerinsoftermaterialsBrassalthoughsoftusuallyhasnotoprakeonthetoolatallOther angles to be aware of are the top rake and the side

rake

CUTTINGTOOLSHAPES

The followingaresomeof thedifferent shapes thatyoumightfindusefulforgeneralturningandmetalremoval

Right-handknifeturningtoolAllrakeanglesare10degrees

Right-hand knife tool This is used for general turning andfacingofbarstockDependingontheworkyouaredoingyoumayfindaleft-handversionofthistooluseful

Typicalroughingtool

Right-handroughingtoolIthasaleadingangleandasmallradius on the tip of the tool This tool is used for fast metalremovalwherefinishisnottooimportantAgainyoumayfindaleft-handversionusefulAroughingtoolcuttingatanangletoabarwillremoveachip

widerandthinnerthanatoolcuttingat90degreestothebarThis improves tool life although you will have to square theturningupwithastandardknifetool

Typicaldouble-sidedroughingtool

Double-sided roughing tool It can turn towards the left orright It canalsobeusedasaplunge tool to removematerialfroma groove orwhere the component needs to be lsquowaistedrsquodown

Simplepartingofftool

Simple parting off tool This is suitable formostmaterialsYouwillprobablyneedalargeoneforpartingofflargediameterbarsaswellasasmalloneforpartingoffsmallcomponents

Internal(top)andexternal(bottom)screwcuttingtools

ScrewcuttingtoolThisisusedforcuttingscrewthreadsTheanglewilldependonthethreadyouarecutting60degreesformetric55degreesforWhitworthandBSFetc

Shallowboringtoolcapableoffacingacrossthebottomofahole

Boring and facing tool This toolrsquos unusual shape will befound very useful when recessing a large bore It will plungestraight intoasmalldrilledholeandwillalso face rightacrossthebottomoftherecess

Double-endedchamfertoolchamferingadiameter

Double-ended chamfering tool It has 45 degree angles atbothendssoitcanbeusedtochamferexternaldiametersandinternalbores

Double-endedchamfertoolchamferingabore

Othershapescanbeusefulbutthetoolsshownhereshouldbesufficienttogetyougoing

BORINGTOOLS

Boring tools are used to clean up a previously drilled holepossiblytomakeitruntruebutmorelikelytoensuretheholeistothecorrectsizeTheyarenormallylongerthanordinarytoolsandtendtostickoutfurtherfromthetoolholderHSStoolsaresuitableformostusesCarbideinsertedtipboringbarsarealsoreadilyavailableandarethebestbetforturningcastironinthesmallworkshop

HSSboringbar

For really small holes down to2or3mm indiameter solidHSSandcarbideboringbarsarereadilyavailableAlthoughtheyarenotcheaptheywillbefoundveryusefulandquicktouseAnothermethodofboringahole is tousea longseriesslot

drillasaboringtoolInuseclamptheshankinthetoolholderwiththepointatcentreheightmakingsuretherestoftheslotdrillisclearofthesideoftheboreYoucanthenrunitthroughtheboreinasimilarmannertoastandardboringbar

Asmallcarbideboringbarinsertedintoamildsteelshank

PARTINGOFFTOOLS

PartingofftoolsprovideaquickwayofcuttingoffworkfromtheparentbarThereisrarelyanyneedtoworryaboutcuttingthecomponentofftothecorrectlengthtogetagoodfinishAslongasthecomponentislongerthanrequireditcanbeputbackintothe chuck or a collet and the parted off face can be faced tolengthorotherwiseworkedonThepartingofftoolcuttingfacecaneitherbesquareoritcan

beangledtotheleftorright(seepage43)Thesideofthepartingofftoolcouldevenberadiusedsothat

it forms a radius on the end of the next component orchamferedtoformalead-inedgeforthenexttool

CUTTINGLUBRICANTS

Tomake cutting tools cut easily and to prolong their life it issometimesbesttouseacuttinglubricantForsteelIpreferneatcuttingoilItlubricatesbutisnotidealforcoolingtheworkIn industry coolant is normally used This is oil that has an

additivetomakeitsolubleinwaterMostsolubleoilswilldobutthe synthetic ones tend to sting your hands if you have anyopen cuts I would not recommend using soluble oils on thehome workshop lathe as I think they tend to wash thelubricating oil off the slideways and can encourage rustHowever this ismypersonalpreferenceandmanypeopleusesolubleoilinthehomeworkshopwithoutanyproblemsOil is suitable for use when cutting steels mild steels

stainlesssteelsandhighcarbonsteelssuchassilversteelThebestlubricantwhencuttingaluminiumisparaffinItstops

thealuminiumfrombuildinguponthecuttingtoolBrassandcast ironarenormallycutdryWhenturningcast

ironona lathe if the latheisfittedwithasolubleoiltankthecastirondustwillhaveanaffinityforthesolubleoilIfthelatheisthenusedonaluminiumthefreecarboninthecast ironcancontaminatethealuminiumwithblackstreaks

Inormallyplacetheoilorparaffininasmalldish(actuallyacatordogfoodbowl)andapply itbyhandwithasmallbrushThisdoesallIneedThenextchapterlooksatgrindinglathetools

4SharpeningToolsandHoldingThemintheLathe

ThenexttaskistogrindasetofusefullathetoolsThe first thing you will need is an off-hand grinder The

grindercanbeadangerousmachineso itshouldbeusedwithcare Eye protection must be worn the guards should becorrectlyfittedandtheremustbeadequateilluminationIdonrsquotlike using a grinder in a small workshop as the grinding dustflies everywhere and canget onto themachine slideways andtools generally making the workshop dusty and dirty Ifpossible set up thegrinder in a separate areaaway from theworkshopIhavemygrindermountedonafoodchoppingboardso I can carry it outside to use This has the addedbenefit ofdaylight although you are dependent on the weather or youmightneedtouseitafterdark

Theguardofthisoff-handgrinderhasbeenwidenedtoacceptarecessedwheel

GRINDINGWHEELS

IthasalwaysbeenstatedthatyoushouldnevergrindatoolonthesideofthegrindingwheelSofollowingthistheorywewillbeusingarecessedwheelwhereitswidthismuchthickerthanthepartofthewheelusedtoclampthewheeltothegrinderIstruggledtofindarecessedwheelof6in(150mm)diameterandfinally found a 60 grit grinding wheel on a personal visit toAxminster Power Tools in Devon (I could find only an 80 gritwheel in theircatalogue)Thewheels I like touse forgrindingare A60K5V if I can get them and I prefer the white wheelsdesigned for the harder tool steels rather than the grey orbrown wheels which are more suitable for softer mild steelsThedesignationbreaksdown like thisA stands foraluminiumoxide 60 is the grit size K is the hardness (I J and K beingmediumhard)5 is thestructure(thespacebetweengrainsofgrit) and V is for vitrified the method of bonding the grainstogetherTheKandthe5canvaryabiteitherwayandthegrit

shouldbe4660or80with60beingpreferredThe80gritisabitfineandwillclogupquitequicklySo-called green grit wheels made from silicon carbide are

available for sharpening carbide tools They are usually softerthanaluminiumoxidewheelsinordertoallowthegrittobreakdownbeforethewheelbecomesglazedfromgrindingthemuchhardercarbide

Witharecessedwheelyoucancutontheouterfaceoftherecessedsideofthewheel

TestingtheWheel

The first thingyoushoulddowhenbuyingawheel is tomakesurethat it is ratedatasufficientlyhighspeedfor thegrinderon which it is to be used Off-hand grinders usually run ataround2900rpmsoyouwillneedawheelratedtoatleastthatspeed it is all the better if the grinding wheel is rated at ahigher speed than the grinder Care should be taken whenhandlinggrindingwheelsastheyarequitefragileifknockedordropped A grinding wheel should only be purchased from areputableengineeringsupplierSupportyourgrindingwheelona piece of wood and tap the wheel gently with a plasticscrewdriver handle or similar The wheel should lsquoringrsquo if itsoundsdullitshouldbebrokeninhalfandeitherthrownawayorusedontheworkbenchasasharpeningstoneNeverthrowawheelawaywithoutbreaking it into twoyouneverknowwho

mightgettheirhandsonit

Thistoolrestwasdesignedtosharpenplaneironsandchiselsbutitisfineforlathetools

Amoderndigitalanglegaugeisidealforsettingthetoolrest

MountingtheWheel

The wheelrsquos bore should be the same as the spindle of thegrindingwheelOften theborewillbe largerandyouwill then

need some plastic spacers to reduce it Spacers should bereadilyavailable fromyour localengineeringsupplierYoucanturn thespacers fromplastic if youcanrsquotbuyany ready-madeonesAt each side of the wheel you should fit a paper washer

thesearemadeofblottingpapertypematerialandwillprobablyhave been supplied already stuck on the wheel The grindershould have twometal flanges one to fit at each side of thewheel Both flanges should be the same diameter These willhold the wheel true and spread the tightening load on thewheelThegrinderwillhavetwodifferent threadsontheendsof its spindle The right-hand side of the grinder will have aright-hand thread and the left-hand side will have a left-handthreadThedifferentthreadsaretostoptheclampingnutsfromunscrewingwhenthegrinderisrunningTofitthewheelremovetheguardandundothenutRemove

the metal flange and then the wheel Make sure the flangesdonrsquothaveany remainsof theoldpaperwasheron themPutthenewwheelontothegrinderspindle(rememberthespacerthepaperwashersandtheflangesateitherside)andscrewthenuthand-tightFinallyholdthewheelgentlyandgivethenutapinchupwithaspannerYoudonrsquotneedtoover-tightenthenutjustsufficiently tostop thewheel fromcoming looseRefit theguard and spin thewheel by hand to ensure it is not rubbinganywhereNowwearealmost ready to switch thegrinder onBeforedoingsohoweverputonyoureyeprotectionandstandtoonesideofthegrindersoyouarenotinlinewiththewheelshould it burst Then switch the grinder on All should be fineandthewheelshouldberotatingsafely

TOOLREST

Theworkrestsuppliedwithanoff-handgrinderisusuallyjustabitofbentsheetmetalboltedonItisusablebutonlyjustI recently purchased a ready-made tool rest as a basis for

makinganimprovedgrindingrestThiswasoriginallydesigned

forsharpeningplanebladesandchiselsforwoodworkingbutitmakes an ideal rest for sharpening lathe tools It is made ofaluminiumandisfullyadjustableforangleThebestmethodofsetting the rest to the correct angle is to use a digital anglegauge These are now very cheap and are readily obtainableThepositionoftherestinrelationtothegrindingwheelcanbeadjusted on its sliding base Many designs for tool rests havebeenpublishedandyoucouldmakeoneofthoseinsteadifyouwishtosavemoneyThetoolclampassupplied isdesignedtoclampplane irons

andchiselssothisneedstobechangedLathetoolsneedtobepresented to the grinding wheel at the correct angles If youdonrsquot have a digital angle gauge this can be achieved usingsimpleguidesmadefromanglesheetmetalandsomescrewsIused gauge plate made from a high carbon steel with anaccurategroundfinishthatcanbehardenedandtemperedbutmild steel would be perfectly suitable if you donrsquot have anygaugeplateavailableYouwillfindaprotractorusefulyoucangetasteelonewith

an adjustable blade for a reasonable price The protractorwillbeusedtosetthetoolanglethatisgroundonthetools

Sheetmetalprotractorsareavailableverycheaply

LATHETOOLGEOMETRY

LathetoolsneedtobegroundtocertainanglesbuttheanglesdonrsquothavetobeexactFormosttoolssomewherehandywilldounless you are grinding a form tool to a particularly accurateshapeIthasbeennormalforbookstoshowtheanglesontoolsas used in a production environment where tools will ideallyhavealonglifeoftenthislifeiscalculatedaslastinganeight-hourshiftsothetoolonlyhastobesharpenedandresetonceadayInthehomeworkshopwecan increasethesecuttingangles

andgetbettercuttingattheslightexpenseofshortertoollifeWehavealreadyexplainedtheshapesof the tools thatyou

willfindmostusefulToolanglesareknownbytechnicaltermstop rake front rakeside rakeandback rakeThe rakeanglesvary depending on thematerial to bemachined but a set ofstandardtoolswillgetyoustartedSomeoftheaccompanyingphotographsareactuallyoflarge-scalewoodenmodels

Theleft-handtoolissuitableforbothfacingandturningtheright-handtoolissuitableforturningonly

Left-handsideofthefacingandturningtoolshowingthefrontandtoprake

Topofthefacingandturningtoolshowingthefrontandsiderelief

Left-handsideoftheturningtoolshowingthefrontclearanceandthetoprake

Topoftheturningtoolshowingthefrontandsideclearanceandthetoprake

GRINDINGATOOL

WhengrindingHSStoolstrytokeepthemascoolaspossibleIfan HSS tool becomes too hot and is then quenched in waterminutecrackswillformonthecuttingedgesThesecrackswillmakethetoolcuttingedgebreakdownveryquicklywhenusedThe best practice is to grind a little bit off the tool and thenquenchitwhileslightlywarmDonotletthetoolgethotdipitin thewater little andoften This should ensure the tool edgedoesnotbreakdowninuse

GrindingYourFirstTool

Most angles can be ground by using the tilting table whileothersmayneedtobefixedinrelationtotheperipheryofthegrindingwheelThefrontandsideofthetoolcanbegroundbytippingthetableatthecorrectanglewhereasthetoprakecanbegroundontheperipheryofthewheelThegrinder should first be switchedoff andunplugged Set

thetoolresttotherequiredangleusingthedigitalanglegaugeoranangletemplateandtightenuptherestBefore switching on the grinder ensure that everything is

freetorotatebyspinningthegrindingwheelbyhandIf all is well put on your safety glasses and switch on the

grinderPlacethetoolonthetoolrestupagainstthesideoftheprotractor Slide the tool along the table until it reaches thegrindingwheel andmetal starts to be removed Slide the toolbackwards and forwards slowly along the restwhile putting alittle light pressure on the tool so that it continues to pressagainst the grinding wheel When you have removed a smallamountofmaterialcoolthetoolbitdownAtnotimeallowthetool bit to get hot Continue grinding until you have removedsufficientmaterialfromthetoolbit

Thegrindingrestissettothecorrectangleof10degreestogrindtheendofthetool

Grindingthefirstangle

TurnthetooltotheotherangleanddothesamesothatnowboththefrontandsideclearanceangleshavebeengroundThis toolwill be enough for brass but for steelwe need to

grindthetoprakeWhengrindingthetoprakeonaright-handtool the slide rest needs to be higher than the centre of thegrinding wheel so that it grinds the tool at approximately 10degrees

Thefirstanglehasbeenground

You have now ground your first lathe tool The tool asreceivedfromthegrinderwillbetooroughtousehoweversoyouwillneedtohonethecuttingedgesYoucandothisonanoilstone(usedwithfineoillike3in1)orwithadiamondlaporusing a combination of the two Lightly lap the front and sideclearanceanglesuntilyougetagoodfinishand lightlyhoneaverysmallradiusonthetipofthetoolFinallyhonethetoprakeangleandyourtoolisreadyforuse

Grindingthesecondangle

Thesecondanglehasbeenground

AllofyourHSSturningtoolscanbedoneinthiswayOnlytheangleswillvaryandthesecanbesetusingadigitalanglegaugeandprotractorAnoccasionalhonewillresharpenyourtoolsaslongasyoutreatthemwithcareA similar range of HSS tools and a parting off tool all with

zero top rake shouldbeavailable if youwill be turningbrassUnless you are doing quantity production one tool holdershouldbesufficientforbrassAsatoolforbrasshasnotoprakeandyouwouldnotnormallygrindthetopawayaslongasyoubuy tool steel of the same size the tip height will remain thesameYoucanthenusethedifferenttoolsinoneholderwithouthavingtoresettheheight

MACHININGCASTIRON

Carbide-tippedtoolsareidealformachiningcastironAsimplebrazedupcrankedtoolwithasmallchamferonthenosewilldoforbothturningandfacingcastironcomponentsThemainuseof this tool will however probably be truing up the faceplatethat comes with the lathe The large diameter combined withtheintermittentcutovertheboltgrooveswoulddestroyanHSStoolinafewsecondsAsmalltippedboringbarwillbeidealfor

taskslikeboringcastironcylinders

Grindingthethirdangle

Asimplediamondlap

Thethirdanglehasbeenground

Tosharpentippedtoolsyouneedadiamondwheelorifyouwant to remove large amounts of carbide a silicon carbidewheeloftencalledagreengritwheelowingtoitsusualcolourSilicon carbide wheels are much softer than aluminium oxidewheels as they need to break down faster to present newsharpergrainstothecarbidetoolAdiamondwheelisonlydesignedtolightlylapatippedtool

itisnotsuitableforremovinglargeamountsofcarbide

Diamondcupwheel

TOOLHOLDING

Smallerlathessuchasarefoundinmostworkshopsmayhaveatopslidewithatoolclampforindividualtoolsablockwithasingle slot to take the tool a four-way turret (or sometimes athree-way)oraquick-changetoolblockandholdersetThereisalsotheso-calledAmericantoolpostwhichisaroundbarwitha slot through it and a bolt in the top to clamp the tool ItusuallycomeswithmatchingdishedwasherstoadjustthetoolheightThistypeisnolongerverycommononlathes

Quick-changeToolPost

Themostversatiletoolholdingsystemisthequick-changetoolblockwithmatchingholdersThedrawbackwiththissystemisthe cost of extra tool holders you need quite a few one foreachtoolThequick-changetoolblockmountsonthefrontofthelathe

normallyontopofthetopslide(Blockscanbefitteddirectlyon

thecrossslidebytheuseofaraisingblocktoaidrigidity)

Quick-changetoolblock

Each holder is set up with its own particular tool The toolholderscanbe individuallysetso that the turning tool isdeadoncentreheightandispresentedcorrectlytotheworkpiece

Quick-changetoolholder

Quick-change tool holders are available with a straight cutslottotakestandardsquareshanktoolholderswithastraightcutwiththeadditionofaVeecut-outinthebottomforusewithroundtoolssuchasboringbarsandasafrontpartingoff tool

holdertotakeahighspeedsteelpartingoffbladeRearpartingoff tool holders are available to take an inverted parting offbladeeitherahighspeedsteelbladeoran insertedtipbladeLeft-handed and right-handed extended tool holders are alsoavailableandmayoccasionallybequiteusefulThetoolblock isnormallymountedonthetopslidebutyou

cangetraisingblockstouseinsteadofthetopslideThismakesthetoolholderblockmuchmorerigidAbackquick-changetoolblockwillneedmountingonaraisingblock

Backofaquick-changetoolholdershowingthedovetailtypeofmounting

Right-handandleft-handextendedtoolholders

StandardtoolholderwithaVeetotakeroundtoolholders

Frontpartingofftoolholder

ToolClamp

Satisfactoryworkcanbedonewithatoolclampedontothetopslideusingshimsteel toset thecentreheightof the toolThemaindrawbacksarethatyoulosethepositionofthetoolwhenyoutakeitoffthetopslidetofitthenexttoolandyoualsolosetheaccuratecentreheightofthetoolunlessyoukeepthetoolandshimstogetherIfyouaremakingonlyonecomponentthisisnotaproblembutitisanuisanceifyouaremakingabatchofmatchingcomponents

Simpletoolclamp

Single-slotBlockToolPost

AblocktoolpostisoftensuppliedwiththecheaperlathesThetoolpostisliterallyablockofmetalwithaslotcutinittotakethe turning tool It is relatively easy to set the tool up at thecorrectcentreheightbyusingvariousthicknessesofshimThisisfineforthebeginnertoturningwhoisjuststartingoutbutitisbesttoreplaceitwithafour-waytoolpostoraquick-changetool post You could of coursemake several block tool postsandkeepeachonesetwithadifferenttool

Four-waytoolpost

Backtoolpost

Four-wayToolPost

Four-wayToolPost

Thefour-waytoolpost isagoodcompromiseona latheasyoucansetfourtoolsintheturretandrotateeachoneintopositionas needed This speeds up production and is a lot faster thanusingasimpletoolclampThedrawback isthatthetoolsstickoutof the turret fourdifferentwaysandyoumightcatchyourhandonasharp toolAsimple ratchetstopensures thateachtool repeats its position when the tool post is rotated so theworkisaccuratelyturnedeachtimethetoolisusedAduplicatefour-waytoolpostwithtoolsforbrasswillspeedupproductionevenmoreCastingsareavailabletomakeyourownthree-waytoolpost The three-way toolposthas theadvantageofbeingable to get close to the work when you are turning betweencentresFor the front tool post I would recommend right-hand and

left-hand roughing tools right-hand and left-hand finishingtools a tool groundup to face barswhile using a half centreand a Mini Thin inserted tip grooving tool with grooving andparting off inserts You will also need large and small boringbarsbothHSSandwithinsertedtipsTheHSStoolsshouldbegroundupforuseasgeneral-purposeturningtoolsformildsteelandsimilarmaterialsThecarbideinsertedtipboringbarshouldbefineforcastiron

BackToolPost

You can fit a quick-change tool block to theback of the crossslideaswellasthefrontSpecialholdersareavailabletotakeaHSSparting off blade or an inserted tip parting off blade Thebladewill be angleddown to give top clearancewhenpartingoffTheseback-mountedtoolblocksareveryhandyastheycanalsobefittedintotoolholderswithafacingtoolorachamferingtoolFor a back tool holder set-up I would recommend an HSS

partingoffbladeafacingtoolforcastironandadouble-ended45-degree chamfering tool that can be mounted parallel with

the chuck or at 90 degrees to it This set-upwill allow you tofaceaworkpiecechamfertheoutsidediameterandortheboreandpartitofftolengthThenextchapterlooksatholdingworkinachuck

5WorkholdingintheChuck

This chapter covers the different types of chucks how to usethemandsetupworkinthemaccurately

Aself-centringthree-jawchuckfittedwithlsquodrilljawsrsquoNotetheexternaljawswhichareinterchangeablewiththedrilljaws

USINGCHUCKS

Themostusefultoolsforworkholdinginthelathearethree-andfour-jaw chucks The three-jaw chuck is usually of the self-centringvarietythistypeofchuckcomesasstandardwithtwosets of jaws The first set of jaws are known as inside or drilljaws as they are most useful for holding round and hexagonbarsTheother setof jawsareoutside jawswhichholdworkusuallyindiscformontheoutsideSelf-centringmeansthatwhenyouinsertabitofbarintothe

chuck and turn the chuck key the chuck centralizes theworkpieceas it tightensup It isunlikely to runperfectly truebutitshouldruntruewithin3or4thouYou can also purchase soft jawswhich are exactly as their

namesuggestsYoucan thenbore themout to fit thework Ifyouborethemonthelatheyouaregoingtousethemontheworkwillrundeadtrue

Asetofsoftjawscanbeturnedorboredtosuittheworktobeheld

Aself-centringfour-jawchuckThesealsocomewithexternaljawsandsoftjawsareusuallyavailable

Self-centring four-jaw chucks can be used for square barsTheyarealsousefulforholdingroundbarswithmoregripthanathree-jawself-centringchuckSoft jawsarealsoavailableforfour-jawself-centringchucks

Afour-jawindependentchuck

Youare howevermuchmore likely to comeacross a four-jaw independent chuck than a four-jaw self-centring chuckIndependent means that the jaws can be moved individuallyand the jaws can also be reversed one two three or four ofthemdependingontheworktobedone

Abaseplatecastinginafour-jawindependentchuck

Wewillfirstlookatthethree-jawchuckThebestmethodofmaking a component in one of these is if possible to turn itcompletely at one set-up If you put a piece of bar into thechuck face the end centre drill drill and ream it skim thediameterandpartitoffitshouldbeconcentricalloverThisisbecausewehaveturneditallatthesamesettingwithouttakingit out of the chuck If we need to machine the other endhoweverwhenwe turn it roundandput it back in the chuckthechancesareitwillnotruntrueThis iswherethe four-jaw independentchuckcomes inYou

canput thecomponent intoa four-jawchuckandset it to runtrueusingthedialtestindicatorAnyworkyoudoonthepartedoff end should then be concentric with the rest of thecomponentWhensettingworkinafour-jawindependentchuckfor a second operation use some thin shimbetween the jawsandtheworkpiecetoavoidmarkingtheworkWorkisoftenheldinafour-jawchuckbecauseitisacasting

anoddshapeorsquareandsowonrsquotfitintoathree-jawchuckIf thework just requires tobe faced flat rightacross the facethereisnoneedtosettheworkrunningradiallytrueItshouldbe near enough on the centre line as long as the work is

reasonablybalancedYou could of course put the component into a three-jaw

chuckbyfittingsoft jawsandmachiningorboringthemouttotake the component This is the best option ifmaking severalcomponentsthatneedtobeidenticalbutifyouonlyneedoneor two components a four-jaw independent chuck will be thequickestmethodofmachiningthemLargerdiameterscanbeheld ina three-jawchuckbyusing

theoutsidejawsThesehavealargeradiusontheinsideofthejaw ifthisradiusis largerthantheworkpiecethejawsshouldnot tend to dig into the work and mark it Outside jaws areuseful forholding components like small flywheels locomotivewheels and chuck backplates when machining the bores ofholesorwhenmachiningacrossthefaceWhenmachining thindiscs it isuseful toputsomepacking

behindthedisctomakeitstandproudofthejawsTostopthepackingflyingoutwhenthemachineisrunningmakeasetofthree or four packing pieceswith grooves at each end and fittensionspringstothemTheyshouldallbethesamediametersothatthebackoftheworkisparalleltothechuckThelengthand grooves can vary slightly as they donrsquot affect theparallelismTheyarequickandsimpletomakesoacoupleofsets of different diameters should find their way intoeverybodyrsquostoolbox

AlthoughmostlathechuckkeyshavesquareendstheyareoftenofdifferentsizesKeepeachkeywithitsownchuck

ChuckKeys

I have alreadymentioned that the chuck key should never beleftinthechuckwhenitisunattended(seeChapter2)PutthekeyintothechuckuseitandputitsafelyawayassoonasyouhavefinishedwithitIfyouswitchonthelathewiththekeystillinthechuckyoumightneedatriptothehospitalDonotuseexcessive forcewhenyou tightenup the chuck

Do not use a piece of tube a spanner or anything else as alever thechuckkeyon itsownshouldbesufficient to tightenthechuckontotheworkWhenusinga four-jawchuckasmallchuckkey littlemore

thanaknurledknobwithasquareoncanbeusedtoadjustthejawsinandoutpriortotighteningupwiththeproperchuckkeyThiswill save timeover adjusting the jawswith a large chuckkeyTo turn the independent four-jaw chuck jaws round a

carpenterrsquosbracewithapieceofsquarebarinittofitthechuckwillmakeshortworkofreversingthe jawsbutdonrsquotuse it forthefinaltighteningasitisliabletostrainthejaws

STARTINGTOTURN

Before going any further you need to learn how to do basicturningFor thisyouneed toput the three-jawchuckonto themandrelStartbycleaningthemandrelwithacleanbitofragorsimilar(Ikeeparollofpaperkitchentowellingintheworkshop)Nowyouneed toclean thechuckrsquosboreand threadusing thetwotoothbrushmethod(seeChapter2)BoththemandrelandthechuckshouldbecleanbeforeyouattempttofitthechucktothelatheSelecting and grinding turning tools has already been

discussed (see Chapter 4) so by now you should have acorrectlygroundturningtoolsuitableforroughingoutapieceofsteelbar

Barwithapiptoolaboveorbelowcentreheight

MakingaToolCentreHeightSettingGauge

Thistoolneeds itscuttingedgesettothecentreheightofthelatheThereareseveralwaystodothisbutoneoftheeasiestiswith a home-made height gaugeWhen starting out this is achickenandeggsituationyouneedtomakethegaugetosettheheightbutyoualsoneedatoolsetatthecorrectheighttomakethegaugeThesimplestwaytoovercomethisproblemistosetthelathe

tooltotheapproximatecentreheightandtakeacutacrossthefaceofthebarDependingonwhetherthereisapipremainingon theendof thebaryoushouldgetan ideahow farout thetoolheightisIfthereisnopipthismeansthetoolisoncorrectcentre height or too high A pipmeans the tool is too lowOfcourse you may have been lucky so try dropping the toolslightly until a pip remains You can then raise the tool a fewthouatatimeuntilthepipdisappearsThetoolshouldthenbeoncentreheight

Barwithnopiptooloncentre

Nowthatthetoolisatcentreheightyoucanmakeasimpleheight gauge Turn a piece of bar down to as close to frac12in(12mm)asyoucangetandleaveitinthelathechuckMeasurefromthetopofthecrossslidetothetopofthebarwithacheapheightgaugeLowertheheightgaugebyhalfthebardiameterTheheight

gaugeshouldbeexactlyonthelathecentrelineMakeanoteofthisdimensionWe now need to look at how to turn a bit of bar to an

accuratediameterWhenturningabartosayfrac12in(12mm)youneedtostartwithsomethingslightlylargerInthiscasethiswillbe⅝in(16mm)diametermaterialasthisisastandardsizeCutapieceofmaterialabout2in(50mm)longandputitinto

thechuckwithabout1in(25mm)stickingoutSkimtheoutsidedown to about 0510 thou or 1225mm which is 10 thou(025mm) above the size required (You should be aware thatmosthobbylathedialsremovetwicewhattheysayaonethoudivisionforexamplewillusuallytake2thoufromthediameterLargercommercial lathesaremuchmore likelytotakeoffonethoupergraduation)Nowtakesmallcutsuntilalmosttosizeusingpowerfeedif

you have it andmaking sure you knock the feed off before ithitsthechuckStopthelatheandwindthecarriagetothestart

of the bar Take another cut at the same setting andmake anoteofthediameterTakeanothershallowcutbutthistimegoonly about frac14in (6mm) along the bar knock the feed off andturn the lathe off Move the carriage towards the tailstock sothat you can measure the bar Continue making this cut andmeasureuntilthesizeiscorrectThenrunthetoolalongthefulllengthof the jobWindthecarriagebacktowardsthetailstockand take a finishing cut or two at the same setting ThediametershouldnowbetheexactsizerequiredIt is not difficult to turn accurately it just takes a little

patienceandpracticeThemoreturningyoudotheeasieryouwill find it is to hold accurate limits If you turn everythingaccuratelywhetheritneedstobeaccurateornotyouwillsoonlearntoturnwithinathouorsowithoutanyproblems

Measuringtheheightofthebarabovethecrossslide

Now we need to make a tool height setting gauge Cut alengthofbarjustoverthedimensionsyouwrotedownandfaceone end turn it round in the chuck and face the other endMeasurethelengthandfindouthowmuchyouhavetotakeoffit to give the dimension you want Put the bar back into thechuck and bring the tool up to the face of the bar Lock thecrossslideFacethebartolengthbyusingthetopslideindexmovingforwardsafewthouatatimeuntiltherequiredlength

is reached Younowhavea tool height settinggauge suitableforthefrontandreartoolsIf you have an inverted Vee bed lathe or if for any reason

youcanrsquotusetheheightgaugeflatonthebedyoucanputtheheightgaugeonaplateon topof the lathebedwhileyouaresettingthetoolheight

Settingtheheightgaugetothelathecentreheight

Settingtheheightofthetool

Usingthesettinggaugetosettheheightofthereartool

TurningtoaSpecificLengthandDiameter

Nowwewill turnabarwithastepon theendToensure thatthestep isthecorrect lengthwewilluseabedstopThiscanbe as simple as a block clamped to the lathe bed to stop thecarriage moving any further I use a simple home-made bedstopthatdoesallIrequireSetthebedstopthenmovethecarriageuntilittouchesthe

stop and lock it Wind the top slide so that the tool is justtouching the end of the bar and lock the carriage For thisexercise we will make the step 16mm long and 12mm indiameterWindthetopslidealong159mmWecannowroughout thestepateachendTurn theenddown toabout02mmabove the finisheddiameterbywinding thecarriagebackandforthYoucanusethe fine feedbutmakesureyouknockthefeed off before the carriage reaches the stop and finish up tothestopbyhandWindthetopslidealongtheremaining01mmto12mmandfinishthediametertosizeandlengthtakinglightcuts as previously Donrsquot forget to clean up the face of theshoulderyouhavejustturnedIfyouneedtouseabedstopatthetailstockendofthelathe

asimplemethodofdoingthisistouseabarplacedonthelathe

bed against the tailstock The bar acts as a stop when thecarriageiswoundbacktowardsthetailstockThistailstockendbed stop is useful when you are turning a groove in acomponentandyouneedstopssetatboth theheadstockandtailstockendsofthelathe

Ahome-madebedstop

TurningWorkontheOutsideoftheInsideJaws

Theoutsideoftheinside(drill)jawsareusefulforturninglargerdiameterwork that is too large to fit inside thedrill jawsThiswillmostoftenbe in the formofa flywheelcastingFlywheelswithsixspokesareidealforturninginathree-jawchuckasthespokes can fit between the chuck jaws Ideally you need totighten up the flywheel until it is tight but not so tight as todistorttherim

TurningasteponabarusingthestopThebarisheldinthethree-jawchuckandsupportedwiththetailstockcentre

Ausefultailstockendbackstopmethod

Holdingaflywheelinathree-jawchuck

Holdingaflywheelintheoutsidejaws

To ensure concentricity you should do as much work aspossibleonthecastingatthesametimeYoushouldbeabletoturntheoutsiderimofthecastingfacetherimfacethebossand drill bore and ream for the crankshaft all at the samesettingAllyouneedtodothenistofittheoutsidejawsreversethecastinginthechucktapitgentlybackontothestepsoftheoutsidejawsandfaceacrossthesecondsideoftherimandthehubUseabitofshimtoprotecttheflywheeldiameterItdoesnotmatter if the flywheel runs exactly true or not as you areonlyfacingitparallelandtowidthnotturninganydiametersto

size

UsingtheSoftJaws

Soft jaws are very useful when a component has to run deadtrue in the jaws for example when making something like agrindingspindlewhereconcentricityisimportantSoftjawslikelytobefoundinthehomeworkshoparesimple

rectangles of steel with the scroll and groove formed directlyintothesoftjawsAnothertypeofjawyoumaycomeacrosshasa grooved pattern in the main jaws that matches a similarpattern in theactualsoft jawsThesoft topsof these jawsareusually interchangeable They are more likely to be found onlarger chucks but you could make your own version for thesmallersizesofchuckifyouwishThemain use of soft jaws is for second operationwork for

examplewhenyouhaveturnedacomponentcomplete fromabitofbarandparteditoffNowyouneedtoholdthecomponenttruetofinishoffthesecondendYoucandothisbyboringoutthechuckjawstotheexactdiameteroftheworkpieceToborethesoft jawstheyshouldbetightened inthesame

direction as they will be tightened in use so that they areoperatingonthesamepartofthechuckscrolleverytimeIfyouhaveathincomponenttomachinefitthesoftjawstothechuckandtightenthejawsontoabitofbarheldinthechuckBesureto leaveenoughspace in frontof thebarsoyoucanbore thejawstofitthework

BoringsoftjawstofittheworkThejawsareclosedontoanoddmentofbartoturntheshallowregistersothatittakesthework

AlwaysusethesamechuckkeyholewhentighteningupthejawsThisappliestoanythingyoudowithaself-centringchuckStampacrossoracentrepopmarkagainstoneof the jaws IsuggestdoingthisnexttojawNo1butanyonewilldoaslongas you always use the samemarked hole Youmight as wellmarkallyourself-centringchucksinthesamemannerCarefullyborethejawstotheexactdiameteroftheworkto

be machined Try to get it exactly on size Undo the jawsslightly remove the bar and replace it with the workpiecewhichshouldnowrundeadtrueAusefulmodificationtothesoftjawsistodrillandtapahole

inthemiddleofthejawsandfitanAllenscrewtoeachholeIfyouwant toholda longbar in thesoft jaws it isnoweasy toboreallthewaythroughthejawsratherthanjustboringastepor part way through All you need to do now is find a disc ofmaterial to put into the chuck ensuring there is sufficientmaterialleftontheinsideedgesofthechuckjawstoborerightthroughtotakethebar

Holdthedisconthescrewheads ifnecessarydrillthediscbeforeboringBorerightthroughthediscandthejawsuntilyouarenearlytosizeatwhichpointyoucanborethroughthediscand test the resultingborewith theworkpieceMakesureyouclean the bore thoroughly before trying the workpiece sinceloose dust can make the hole seem smaller than it really isWhentheworkpieceenterstheborefinishboringrightthroughthe jawsgo througha coupleof timesat the samesetting totakeoutanyspringintheboringbarYoucannowremovethedisc clean the jaws and put the workpiece right through thechuckcheckingthatitrunsdeadtrueThisoperationmaysoundtimeconsumingforasingle item

but if you have several components to make it will save aconsiderable time on setting up each bar individually to runtrue

BoringsoftjawsusingaringThesoftjawshavethreeAllenscrewsthatarecloseddownontotheringwhileboring

TurningtheoutsideofthesoftjawsusingaringThesoftjawshavethreeAllenscrewsthatareopenedupontotheringwhileturning

NowthescrewsareinplacewecanworktheotherwayroundandholdcomponentsontheoutsideofthejawsTodothisyouwillneedaringofasuitablesizeontowhichyoucantightenthejawswith the jaw loading acting outwards so any componentyouputontheoutsideofthejawswillberunningconcentricallyThiswill be ideal for itemssuchas tractionenginewheel rimsandotherlargehollowortubularworkpiecesOne other use for soft jaws is to hold irregular-shaped

components Put a piece of bar into the soft jaws and bore aholeofanysizeand thencleanup theboreso thatallof thejawsare true Transfer the chuck to themillingmachine tableandclampitdownUseatestindicatortocheckthattheholeinthechuckistrueYou can now mill a nest to take any irregularly shaped

component confident that when the chuck is returned to thelatheitwillberunningtrue

Plungertypedialtestindicator

Levertypedialtestindicator

DialTestIndicators

Therearetwomaintypesofdialtestindicatortheplungertypedial test indicator as its name suggests works on a plungerprinciplewhilethelevertypedialtestindicatorhasastylusonthe end The lever stylus is usually ball-or pear-shaped and isfixedtothedialtestindicatorwithafrictionfitmeaningthatitcanbemovedupanddownontheendofthedialtestindicator

throughawidearctoputitintothebestpositionforuseThe plunger type dial indicator usually has a maximum

plungermovementoffrac12in (12mm)butplungermovementsofupto2in(50mm)areavailableTheplungertypedialindicatoris non-reversing and needs an adaptor to enable it to clockholes true Instead of a stylus it has an interchangeable endoften with a ball fitted various interchangeable ends areavailableoryoucanmakeyourownThe lever dial test indicator has a much smaller range of

travelarangeof0008in(02mm)isverycommonItisusuallyeither self-reversing (itmoveswhen in contact with theworkdependingonwhichwayitismoving)oritmaybereversedbyusinga lever on the sideof thedial test indicator both typesarequite commonSince the stylus isdelicate combinedwithitslimitedtravelrangeyoumustbeverycarefulnottobreakitAplungerdialindicatorcanbeusedasadirectreadoutofthe

travel and will be found to be very accurate Owing to therelativelylongtravelifyouwantedperhapstooffsetthecentreofabitofbar in the four-jawchuckby0125in (318mm) thiscanbedonebyturningthechuckbyhandandsettingthebaruntil the indicator travel shows 0250in (635mm) which is0125in (318mm) offset The lever dial test indicator is of nouseforgivingdirectreadingslikethisbutshouldbeusedasacomparatorwherethereadingtakenisforexamplezeroatallpointsofthetravelThedial test indicator is usuallymounted on amagnetic or

vacuum base but is sometimes fixed to a block that can beclampedtothelathemostoftenonthecrossslideSometimesthedialtestindicatorcomesasacompletekitincludingvariousmountingcomponents

Clockingtheendofacastinginafour-jawchuck

Four-jawChuck

To set thework up in an independent four-jaw chuckwe firstneed to know what part of the workpiece should be on thecentre If theworkpiece is a castingwemay have an outsidediameter or a hole that needs to run true in this case wewould put a dial test indicator onto the work and adjust thechuckalittleatatimeuntilthediameterrunstrueDonotturnthe chuck with the indicator in the hole Instead wind thecarriage forwards until the clock enters the hole and take areadingWind thecarriageback rotate thechuck90degreeswindthecarriageforwardandtakeanotherreadingAdjusttheworkinthechuckuntilitrunstrue

WhereacastingisstickingoutashereyoushouldtrytosupportthecastingwitharunningcentreThiswillhelptostopthecastingshiftinginthechuck

LatheCentreFinder

If there isnodiameterorholeyoumayhave tomarkout thecentreontheworkusingaheightgaugeandcentrepopitwithacentrepunchThenyoucanuseawobblerandatestindicatortosettheworktrueItwasoncepossibletogetalathecentrefinderconsistingof

a bar about 6in (150mm) long pointed at both ends with auniversaljointabout1in(25mm)fromthefrontendInusetheshortfrontendgoesinthecentrepopoftheworkinthechuckWhen you rotate the chuck by hand the pointed short endfollows the eccentricity of the centre hole which ismagnifiedaboutsixtimesatthetailstockendYouthenjusthavetoadjustthechuckuntilthetailstockendisrunningtrueatwhichpointthe centre in the work will also be running dead true I donrsquotknow anyone who makes these and second-hand ones areextremelyrare

Asimplehome-madecentrefinder

You can make a simple version of this that works well byusingamillingmachinepointedcentrefinderThisisaparallelbarwithaseparatemoveablepointedendThetwocomponentsare held together with a spring inside You need the pointededge finder a Morse taper parallel adaptor (the Morse tapershould fityour tailstock)aspringandashortstubofbar thatwillfitinsidethetaperedholderrsquosboretostopthespringgoingrightthroughPuttheshortstubofbarintothetaperinsertthespring follow up with the centre and put the Morse taperadaptorintothetailstockBringthetailstocktowardsthechuckuntil the centre of the centre finder is in the centre pop ThespringwillholditinplaceTousetheimprovisedcentrefinderput a dial test indicator onto the parallel part of the centrefinderrsquospointandrotatethechuckbyhandThepointwillrotateeccentricallyadjust thechuckuntil thecentre finderrsquospoint isrunningtrue

Usingascribingblockwithadialtestindicator

Move the tailstock along the bed until the point of thewobblerisinthecentrepopontheworkPutthetestindicatoronthefrontdiameterofthewobblerandadjustthechuckjawsuntilthewobblerisrunningtrueWhensettingupacastingorsomethingsimilarwherenotall

of the diameters are machined you should use the dial testindicator on diameters thatwill not bemachined such as theinsideofaflywheelrimWhenyouhaveturnedallthefinisheddiameters they should then be true with the unmachineddiametersSetting work in the four-jaw chuck depends on the

componenttobemachinedIfyouareusingroundmaterialyoucansetittoruntrueusingadialtestindicatorHoweverifyouaresettingaroughcastingthevariationofsizeandroughnessofthecastingsmaywellbeunsuitableforadialtestindicatorThere are alternativemethods of settingwork up in a four-

jawchuckespeciallyforcastingsOneofthesimplestmethodsis toholdasquarebar in the lathetoolholderandusethis tosetthejobtrueInuseyouwindthebaruptotheworkandsetthedial tozeroorotherwisemakeanoteofwhere it isWindthebaroutorawayfromtheworkTurnthechuck180degreesand wind the bar up against the work again You can

immediatelyseewhichwaythebarneedstomovesothatitisrunningtrueAdjustthecastinginthefour-jawchuckandmovethecastingtowardsthecentrepointRepeatuntilthecastingisrunning true This method is also useful if you are setting asquarebar to run true Justcheckeach faceof thesquarebarwiththebitofmetal

Settingacastingbyusingasquarebar

StickyPinMethod

An alternative the sticky pin method is especially suited tolocomotive wheels or flywheels An ordinary household pin ismounted in plasticine or Blu-tack perhaps stuck on the lathetool and is arranged to point to the inside diameter of thewheelor flywheel thearea that isnotmachinedbut is leftascastAdjustthecastinguntiltheunmachinedfaceisrunningastrueasyoucangetitandthewheelisreadytoturnThestickypinmethodisalsousefulforsettingupworkthathasachuckingspigot such as a locomotive smokebox door Just hold thechucking spigot in the four-jaw chuck and adjust the castinguntilitrunstrueontheoutsidediameterandthefrontface

Usingacommercialstickypintosetworktrue

Themethodsofcentringworkinthefour-jawchuckthathavebeen discussed are also suitable for setting work true on thefaceplate The next chapter looks at turning between centresandusingthefaceplate

6TurningbetweenCentresandFaceplateWork

Thischapterdealswithbasicturningbetweencentresandthenintroduces turning with the work mounted on the lathefaceplate

Headstockcentreanddriverplate(alsoknownasacatchplate)

TURNINGPLAINBARSBETWEENCENTRES

The most basic way of holding work for turning is between

centres Turning between centres is literally holding thecomponenttobemachinedbetweentwocentreseachofwhichhas a 60-degree included angle The headstock centre usuallygoes round with the headstockmandrel although some olderlatheshadanon-rotatingcentreandthedrivetotheworkwasbyapulleymountedontheworkThetailstockcentreisoftenafixedcentrethatdoesnotgoroundalthoughcentreswithballbearingscalledrunningcentresarereadilyavailable

Tailstockplaincentre

The component to be turned usually a shaft has a female60-degreecentreinbothendsthatisusedtosupporttheworkThe work can be turned round between centres so that bothends of the shaft can be machined Because the work ismountedbetweencentresbothendsoftheworkwillbetruetoeachother

Tailstockrunningcentreso-calledbecauseitrunsonballraces

CentringtheBar

FirstwehavetoputthecentresintoeachendofthebarIfthebarisshortsayuptoabout6inlongholdtheworkinthethree-jawchuckanduseacentredrillinthetailstockdrillchucktoputacentre intothebarAcentredrill isashortdrillwithasmallpilot on the end that has a 60-degree taper to the bodydiameterAbettermethodof centring thebar especially longbars is by using a three-jaw chuck and the fixed steady Thebarisheldinthethree-jawchuckwiththeotherendsupportedin the fixedsteadyand thecentre is formed in theendwithacentredrillAusefultoolthatcanbeusedtofindthecentreoftheshaftis

thecentresquarewhichisametalbladewithaVeeonitthatlocatesonthediameterofthebarMarkalineacrosstheendofthebarwitha scriber turn the centre square90degreesandthenscribeanotherlineWherethetwolinescrossisthecentreof thebar Tomake it easier to see the scribed linesblackenthe end of the bar with a permanent felt tip marker beforescribingCentrepunchthepointwherethetwolinescrossandput a 60-degree centre in each end of the bar using a centre

drill in a power drillHold thebar in a bench vicewhile doingthisPutacentredrillintothetailstockdrillchuckandinsertthebar in the three-jaw chuck Make sure the lathe is on a lowspeedabout300rpmwindthetailstockinandjustlightlycleanupthecentreholewiththecentredrilltotrueitupAnotherusefultooltofindthecentreofabarisabellcentre

punchThiscomprisesaconewithacentrepunchinthemiddleIn use place the bell end on the end of the bar and tap thecentrepunchwithahammertomarkthecentreTheendofthebar though needs to be reasonably square if using the bellpunchmethodThere are other similarmethods of centring bars but those

givenherewillbealltheturnerneedstolearn

Turningbetweencentres

Centringthebarusingthefixedsteady(Notethatthefrontclampisnormallydoneupwhileinuse)

Asimplecentresquare

Crosssectionofbellcentrepunch

MachiningtheBar

NowweneedtomountthebarbetweencentresThisissimplyamatterofputtingthebarbetweencentresandtighteningthetailstocksoitislightlypressingintothecentreintheendofthework To drive the work a carrier is fixed to the shaft andengagesapininacatchplatemountedonthelathemandrelAcatchplateissimplyablankdiscwithapinstickingouttodrivethecarrierthat isfittedtotheworkThecarrier isfittedtotheworkusinganAllenscreworboltTostopanymovementofthebarinrelationtothecatchplatethecarriercanbewiredtothecatchplatepinThiswill stop thecarrierand thework flappingaboutItisparticularlyimportanttostoptheworkfrommovingin relation to the catchplate when screwcutting betweencentres

Facingoffabarusingthehalfcentre

Nowthatthebarissafelymountedbetweencentreswecanstart turning it tosizeNormally the first thing todo is to facetheendsofthebartothefinishedlengthDecidewhichendofthebarhastheshallowercentreWewillmachinethisendfirstYouwillneedahalfcentreso-calledbecausealmosthalfofthecentre is missing This means the lathe tool can reach rightacrosstheendoftheworkwithouttouchingthehalfcentreWhenusinganyfixedcentreinthetailstockputabitofoilor

grease into the centre before use and top up as necessaryLightlywindthetailstockbarrelagainstthecentreandlockthebarrel so it canrsquotmoveSwitch the latheonandwind the toolacross to clean up the end Reverse the work and clean theotherendupat thesamesettingBothcentresshouldnowbethesamedepthMeasuretheoveralllengthofthebarTakethefinished length required from the overall measurement youhavejustmeasuredDividethisbytwoandthisishowmuchweneed to take off each end of the shaft so it finishes at therequiredlength

Askimmedbar

Ifyouhaveonechangethetailstockhalfcentretoarunningcentre if you donrsquot have a running centre change to a fixedcentreThehalfcentreshouldonlybeusedwhenfacingtheend

of the bar We will nowmachine the rest of the bar For thepurposeofthisexamplewewillassumethebarhasafinisheddiameter in themiddle with a step at each end First we willmachine the overall diameter to size To do this we need toskimthediameterandcheckthesizeTakeafinecutalongthebarusingthefinefeedifyouhaveoneMeasurebothendsofthebar Ifyouhavesetthelatheupcorrectly(seeChapter2)thebarshouldbeparallelIfitisnotadjustthetailstockbeforecontinuingAssumingthebarisparalleltakeanothercutortwosothatyouareabout01mmlargerthanthefinisheddiameterNowmove the tool in until almost at finished size and take alight cut about 10mm long along the bar Repeat this cut toensure the tool is notpushingoffMeasure thisdiameter youwill probablyhave towind the tailstockbarrel back toget themicrometerontotheendofthebarOnlymovethebarrelbackdo not slide the entire tailstock backMeasure the bar to findouthowmuchtoremovefromthediameterTakeanothershortcutandcheckforsizeWhenthebariscuttingtosizemachineall thewayalongYouwillprobablyhave to take twoor threecuts at the same setting until the bar ismachined to finishedsizeNowwewill turn the stepson theends Toensure that the

stepsare thecorrect lengthwewilluse thebedstopSet thebedstopthenwindthetopslidesothatthetoolisjusttouchingthe end of the bar For this exercise we will make the steps12mm long Wind the top slide along until the tool is justtouching the end of the turned bar Wind the top slide along119mmWecannowroughoutthestepateachendTurntheenddowntoabout02mmabovethefinisheddiameterYoucanusethefinefeedbutmakesureyouknockthefeedoffbeforethecarriagereachesthestopandfinishuptotheendbyhandRepeat for the other end Wind the top slide along theremaining01mmto12mmandfinisheachendinthesamewayasyoufinishedthemaindiameterDonrsquotforgettocleanupthefaceoftheshoulderyouhavejustturnedCongratulations you have just turned an accurate shaft

Donrsquotworryiftheshaftisatinybitundersizeyoucanprobably

makethematingholestofit

Thefinishedshaft

Usingachuckandarunningcentre

Usingthemethodsetoutaboveyoushouldnowbeabletoturn any shaft you require within the capacity of the lathe Avariationoftheabovemethodwheretheshaftissingle-endedistoholdoneendinthethree-orfour-jawchuckandsupporttheotherendwithacentreinthetailstock

Alargefaceplatesmalleronesareavailable

FACEPLATEWORK

Another basic way of holding work is on the faceplate Thismethod is used when the component is too large or isawkwardly shaped andwould be difficult to hold in a three-orfour-jaw chuck Usually the work is clamped directly onto thefaceplate often with a packing piece behind it to protect thefaceplateThefaceplateshouldbeflatandtruesothefirstthingtodo

whenyougetthelatheistocheckthefaceplatewithadialtestindicatorCarefullycleanthemandrelnoseandtheinternalholeinthefaceplateMakesurethemandrelcanturnfreelybyhandwith the lathe switched off and check that the face of thefaceplateisrunningtrueasclosetotheouteredgeasyoucanget If it is runningtrue runthetest indicatoracross the frontfaceofthefaceplatethisshouldbetrueaswellIfthefaceplateis running out itwill need to bemachined Put the lathe intobackgear if ithas it (topbackgearwillprobablybe fine)Youwill need a carbide-tipped tool ideallywith a small 45-degreechamferonthetipBringthetooluptothefaceplateand lockthe carriage Next you need to lightly face the faceplate right

acrossitsdiameterIfyouhaveapowercrossfeeditwillmakelight work of this but if not you can feed across by handFortunatelymost faceplateshavea series of rings on them toaid in setting up the work Machine the faceplate from theoutsidetothefirstringandstopforarest feedtothesecondring and so on until finished Depending upon how badly outyourfaceplateisyoumayhavetodothismorethanonceuntilit iscleanedupbutwhen it isdoneyouwill rarelyneedtodothisexerciseagain

Machiningaholeinablock

Asmentionedpreviously the ringsmachined on the faceplateareguidestohelpyousetuptheworkThiswilldoiftheworkisaroundcomponentbutweneedadifferentmethodiftheworkis square Take a block of metal for example that has beenmachinedalloverWewanttomachineaholeinit2infromoneedgeand1in fromanother edgeMarkout thepositionof theholeandcentrepunch it Put adeadcentre into the tailstockholdtheblockontothefaceplatebringthetailstockuptowardsthechuckandlockitWindthetailstockbarrelandcentreuptothe component and engage with the centre pop Lock thetailstock barrel Clamp the block to the faceplate using somepackingpiecesandfourclampsontheblockTheholeisnowoncentreandwecanmachineitinthecorrectplaceIf we need more than one hole placed accurately in the

componentwecanusetoolmakerrsquosbuttonstoensuretheholesare in the correct place Toolmakerrsquos buttons usually come insetsof fourOnebutton isusually longer than the rest soyoucanstillclockthediameterwhenitisclosetoanotherholeSetsare often available second-hand on eBaywhile they probablyhaveanobscureAmerican threadyoucanclamp themto theblock using your own BA or metric screws together with awasher

Settingupthefaceplateusingthetailstock

Asetoftoolmakerrsquosbuttons

Tofitthemtothecomponenttobeboredmarkoutdrillandtap holes in the approximate positions where the holes areneeded If you need a pair of parallel holes place thecomponentonasurfaceplate looselyfitthebuttonsandpushthem down onto a parallel or similar block of the correctthicknessandnipthescrewsupThespacershouldbesmallerthanrequiredbyhalfthediameterofabuttonIftheholesneedtobeacertaindistanceapartuseaspacer

of the correct size between the buttons (Remember tomake

thespacersmallerbyonediameterofthebutton)

Settingupacomponentusingtoolmakerrsquosbuttonstogetafixeddistancefromtheedgeofacomponent

TherearelotsofdifferentwaystosetthespacingofbuttonsItismainlyamatterofcommonsenseCastingsandflatcomponentscanbeboltedtothefaceplate

for machining A typical example of a flat component is aneccentric strap This type of component is usually made of acomponentthatiscutinhalfandboltedbacktogetherAholeisthenboredinitonthecentrelinetofittheeccentricThistypeofcomponentisoftendifficulttoholdinthelathechuckandisprone to distortion Castings are often too large to fit into alathechuckandso the faceplate iscalledon toundertake theworkAcastingcanoftenbebolteddirectlytothefaceplatetofacilitateeasymachining

Settingupacomponentusingtoolmakerrsquosbuttonstogetafixeddistancebetweenthecentresofacomponent

Work on the faceplate is often an odd shape or is set off

centreThiscauses it tobeunbalancedandasaconsequencethe lathemayvibratewhile thework is turningTocounteractthis tendency the faceplate should be counterbalanced byboltingweightsontoitAusefulsourceofweightsisthelathersquoschange wheels By bolting a change wheel or two onto thelightersideofthefaceplateyoucanbringthewholeassemblybackintobalanceAfterboltingthechangewheelsonspinthelathe by hand to check the balance The faceplate should notshowatendencytostopatoneparticularpointWhenyouarehappy that the faceplate is in balance the work and balanceweightsareboltedontightlyandsothattheworkdoesnotfoulthe lathewhen turnedbyhand switch themachine on in lowback gear to check for vibration Depending on what you areturning you should be able to run in top back gear or evenbottomdirectspeed

Asimpleclampsetisveryusefulwhenmachiningacastingonthefaceplate

TurningaFlywheel

Oneofthemainusesofafaceplateisturningalargediameteriron casting typically a flywheel or a locomotive wheel for asteamengineTheflywheelshouldbemountedsothattheinneredgeoftherimandtheouteredgeofthehubruntrueIfeitherofthemrunsoutitwouldbebetterthatthehubrunsoutasthe

rimwillbemorenoticeableonthefinishedengineClamp the flywheel down with some packing under the

spokessothatyoucanturnrightacrosstherimBecarefulthatyouclamptheflywheeltightenoughsothat itdoesnotmovebutnotsotightthatitdistortsRoughturn theoutsidediameterand facetherimusingthe

backgearUsingadirectdrivespeeddrillandborethecentrehole and either finish off with the boring tool or use a reamDonrsquot try reamingwithout boring the chances are that if youdotheholewillnotbetruewiththerimasthedrillprobablydidnotcutanaccurateholeDropdowntothetopbackgearspeedface the rim and turn the outside of the rim to the finisheddiameter Turn the flywheel over and finish the other face towidth

Astubarborsuitableforcentralizingalocomotivewheelorflywheel

TurningLocomotiveWheelFlanges

LocomotivewheelflangescanbeturnedonafaceplateYoucanpurchase blank end Morse taper arbors that fit into theheadstocktaperFitoneoftheseandturnaspigotonittotake

thewheel bore Thewheel bores should all be the same sizebut if they are different sizes machine the spigot to fit thelargestboremachinetheflangeonthatonethenmachinethespigotdowntofitthenextonemachinetheflangeandsoonIdeally the wheel bores should all be the same size but if

theyarenotproceedas followsSkimtheoutsidediameterofthe wheel flangemeasure and take it to the correct finishedsizeMovethelathetoolinbythedepthoftheflangeandturnthe tread Deal with all wheels like this machining all of theflangeoutsidediameterstothesamesizemovinginthecrossslidebythesameamounteachtimesothatallthetreadsendupthesamesize

UsingtheKeatsVeeangleplatetoturnaneccentriccomponent

KeatsVeeAnglePlate

TheKeatsVeeangleplate ismountedon the faceplateand isusedtoholdroundbarsquarebarandmiscellaneouscastingssuch as cylinders and steam chests The angle plate can bemountedanywhereonthefaceplateaslongasthelathecanbe

rotated safely and is in balance When spun by hand thefaceplateshouldnotshowatendencytostopatanyparticularplacewhenrununderpowerthelatheshouldnotvibrateAswellasholdingbarandcastingsforturningtheKeatsVee

angleplateisveryusefulformakingeccentriccomponentssuchastheeccentricsforasteamengineTo turn an eccentric use a test indicator to check that the

roundbarisrunningreasonablytrueWhenthisissatisfactoryyoucanturntheoutsidediameterofthebartofittheeccentricstrap (or component) including any step or groove requiredNextoffsettheKeatsVeeangleplatebytheamountyouwantthe eccentric lsquothrowrsquo to be Use the dial test indicator tomeasure the offset of the outside of the eccentric The offsetshouldbetwicethethrowYoucannowdrillboreandreamtheholeintheeccentricYounowhaveenoughbasic knowledge to carryout turning

between centres andwork accurately on the faceplate In thenext chapterwewill lookat holdingwork in a collet andonamandrel

7ColletsandMandrels

Thischapterexplainsallaboutholdingworkinacolletandhowyou canmake and use several different types of mandrel forworkholding

ERcollets

USINGCOLLETS

Quite a few different collet systems are to be found inworkshops Some are used for holding tools such as millingcutterssomeareusedforbarorworkpieceswhilesomemaybeusedwithbothbarandworkpiecesOne of the commonest is the ER collet which comes in

severaldifferent sizeseachhavingadifferent largediameterTheERcolletsystemallowsupto0039in(1mm)collapseofa

colletalthough in thesmaller sizesyoucanbuy thecollets in05mmincrementsA16mmcolletforexamplewillholdroundmaterialdownto15mmdiameterWhatevertheERcolletsizetheyallappear togodownto1mmminimumwhichwillclosedownto05mm

ERcolletadaptor

TherearemanytypesandsizesofERholderavailableAlltheusualMorse taper shank sizes are available and you can alsobuyvariousdiametersofextendedparallel shankholdersTheproblemwiththeseisthattheyaregreatforholdingtoolsthathave a short shank but because you need to use the holderwithadrawbaryoucanrsquotputlongbarstockrightthroughthemTo overcome this for lathe work you can also buy ER colletholdersdesignedtobefittedtoachuckbackplatethatyoucanmachine to suit your lathe so ensuring good concentricityBecause they donrsquot use a drawbar you can fit bar stock rightthroughandintotheheadstockmandrel

ERcolletadaptorfittedtoabackplateIalwaysleavebackplatesoversizesoIhavesomethingwithwhichtoclampthemdownwhenusedonamillordrill

When buying new and second-hand ER collets make surethey have the retaining groove near the nose end The older(andobsolete)EandEScollet typesdonothavetheretaininggrooveandarenotinter-changeableYouaremostlikelytofindEandEScolletsincludedwithasecond-handUnimatlatheDraw-in collets are usedwith a drawbar or collet tube The

drawbardrawsthecolletuptightbydrawingit intothelathersquosmandrelbyabar that runs through thecentreof themandreland screws into the centre of the collet Thismeans that youcannotputbarstockrightthroughthecolletToovercomethissome Morse taper collets use a hollow draw tube the collethaving an external thread tomatch the internal thread of thedrawtube

Draw-incollet

Special collets are made for the Myford ML7 Super 7 andML10 lathes These are Morse taper collets but rather thanhavingadrawbartheyareclosedwithanoseringthatfitsoveragrooveinthecolletThenoseringtightensthecolletintotheheadstockmandrelrsquos Morse taper It is extracted after use byundoing the nose piece which draws the collet out from theMorsetaperbythenosegrooveImperialandmetriccolletsareavailableuptofrac12in(12mm)diameterDead lengthcolletsareavailable that fit intoanattachment

usually fixed to the front of the lathersquosmandrel These colletsarecalleddeadlengthbecausetheydonotmovelongitudinallyunlike draw-in collets You are more likely to find collets likethesesecond-handratherthannew

BoxedsetofMyfordcollets

Deadlengthcollet

AvariationofthedeadlengthcolletistheCrawfordMultiborecolletThissystemhascolletsmadeofsegmentsheldtogetherbyspringsThecolletsareofvariablediameterandhavequitea

largeclosurerangeTheyaremorelikelytobefoundonalargercommercial lathe although you can get collets for smallermachinesWatchmakerrsquoscolletscanbeused inmost lathesbymaking

an adaptor for the headstock and a drawbar (or tube)Watchmakerrsquos collets are very accurate and can go down toverysmallsizesbuttheyhavelimiteduseinmostworkshopsYou can get a special watchmakerrsquos spindle for the EmcoUnimatlatheandthereisalsoaversionoftheCowellslathetheCW90thattakeswatchmakerrsquoscolletsFormost of thework carried out on the lathe youwill find

thatanERholder thatmountsontoachuckbackplate ismostuseful

Simpleexpandingmandrel

Simpleplainmandrel

MAKINGMANDRELS

There are several types of mandrel in common use inworkshops The most common is probably the expandingmandrelwhichcaneasilybemadeinanyworkshopInitsmostbasic form it is a bar turned to a size to fit the bore in theworkpieceItisthenthreadedwithataperedtapandslitat90degrees togive foursegmentswhichare thenexpandedbyascrewfittedintotheendofthemandrelAnother common mandrel is the tapered mandrel This is

usuallyalsquobetweencentresrsquomandrelandisoftenmadetotaperfromjustacoupleofthouovernominalsizetoacoupleofthouunder nominal size It is usually hardened and has a groundfinishTheworkpieceisheldinplacebybeingpushedontothemandreluntilitistightToremoveitjustpressitbackoutthewayitwentinWhereconcentricityisnotquitesoimportanttheworkpiece

canbeputonaplain turnedmandrelandtightenedupwithaboltandflatwasherExpandingmandrelsarealsomadecommerciallybutasyou

need a mandrel for each individual size of hole it can getexpensive if you need more than one or two different sizesCommercialmandrelscanbeobtainedwithMorsetapershanksto plug straight into the headstock Thismethod ensures thatthe mandrel should run dead true assuming both the Morsetapermandrel and theMorse taper in the headstock are bothcleanandfreefrommarksorswarfYou can also purchase Morse taper arbors with blank end

pieces from which to make your own mandrels First we willmake an expandingmandrel from a blank Morse taper arborYouwillneedtoturnthearbordowntofittheworkpieceboreIusually turn themandrelabout0010in (0025mm)oversize tostartwithandthenIdrillandtapthearborwithataperedtapThe drilled hole can go quite deep but the tapped hole onlyneedstogoinuntilthelockingbolt isabouthalfwaydownthelengthwheretheworkpiecewillsitPut the mandrel into the vice and cut along the mandrel

making four cuts around the circumferenceRetap thehole to

cleartheswarf fromthethreadandputthemandrelback intothe headstock taper Now you can lightly nip the screw up toexpandthemandrelslightlySkimthemandrel to finishedsizeuntil the workpiece will fit on without shake You can nowfurther tighten the screw so that the workpiece tightens ontothe mandrel When you slacken the screw the workpiece willcome off easily as you have skimmed it while it was slightlyexpandedYoucanmakeanexpandingmandrelfromabarheldin the three-or four-jawchuckorperhapsacollet inasimilarway Ifheld inachuck itmaynotgoback true ifyouneed touseitagainsoifpossibleyoushouldholdthearborinacolletFor aplainmandrel turn thediameter to fit theworkpiece

anddrillandtapforacapscreworaboltThereisnoneedtosplit this type ofmandrel You simply put the workpiece ontothemandrelandholditonwithaflatwasherAgainitdoesnotmatterwhetheryouuseabarinachuckorcolletorifyouusea Morse Taper blank arbor Arbors are very useful in theworkshop If youmake them fromMorse taper blanks or holdtheminacollettheycanbeusedoverandoveragain

8TaperTurningandLatheAccessories

Thischapterexplainshowyoucanturnataperusingatopslidetheuseoffixedandtravellingsteadiesandformtools

Turningataperwiththetopslide

TAPERTURNING

SometimesyouwillhavetoturnataperintheworkshopThatisa fairly easy jobWhat ismore difficult however is having toturnmatchingmaleandfemaletapers

Themethodyouaremostlikelytouseintheworkshopistoturn the two tapers with the top slide You should be able toturna taper longenough foraMorsetaperusingthismethodThemostimportantthingwhenturningtapersistoensurethatthe tool tip is at the exact centre height of the lathe This isbecause the taper will vary if the tool is not dead-on centreheightProbably the easiestmethod of turning aMorse taper is to

useadial test indicator toclocka lathecentreof therequiredMorse taper between centres The smaller end of the tapershouldbeatthetailstockendofthelatheThetopslideshouldbewoundalongthetaperby itshandwheelwhilethecarriageremainslockedThetopslideshouldbeadjustedangularlyuntilthedialtestindicatorreadszeroallthewayalongNowyoucanfinish turn the external Morse taper using an internal MorsetapersleeveasagaugetocheckthattheangleiscorrectTodothis make marks with a felt tipped pen along the taper andcheck that the test sleeve rubs evenly all the way along themaletaperAdjustifnecessaryuntilyouhaveaperfectfitToturnthematchingfemaletaperthelargeendofthetaper

willbeat the tailstockendand theboringbarwillbe invertedandcuttingon thebackof theholeDoing thismeans thataslongasbothofthetoolsareatcentreheightthetapersshouldmatchWecanusethemaletaperthathasjustbeenturnedasatestbarBoreoutthetaperverycarefullyyouwonrsquotneedtoremovemuchmaterial before the test taper goes too far intothe finishedbore Testwitha felt tippedpenuntil youhaveaperfectfitYou can turn any taper you need this way you are not

restrictedtoMorsetapersAnothermethodmostoftenusedforlongshallowtapersistouseataperturningattachmentTheseattachments are often available as extras on higher qualitylathes They comprise a slide mounted onto the back of thelathe Often the guide is dovetailed with a sliding blockattached to the cross slide to guide the tool on a taper ThedepthofcutisusuallyputonusingthetopslidesincethecrossslideisusuallydisconnectedfromthefeedscrewInthiswayit

isfreetomoveinandoutcontrolledbytheguide

Taperturningattachment

Settingthetopslidebyclockinganexistingtaper

Anothermethodweshalllookatfortaperturningistooffsetthe tailstock on its base This will make the work turnedbetween centres become tapered either large or small at thetailstockenddependingonwhichwaythe tailstock isoffset ifsettowardsthebackofthelathethediameterwillbelargerat

the tailstock end if the tailstock is moved to the front thetailstockendwill be smaller indiameter Theamountof taperthatcanbeturnedinthismannerislimitedsincetheheadstockandtailstockcentresareoutoflineThe final method of offsetting the workpiece is by using a

boringhead inthetailstockYouneedahome-madehardenedsolidcentrethatfitswheretheboringtoolwouldnormallygo(AsmallUnimatlathesizerunningcentremightbeideal)SettheboringheadsothetooltravelishorizontalYoucanthenoffsettheboringheadcentresocreatingataperThisisthesameassetting the tailstock over but you donrsquot have to realign thetailstockafterwards

Usingthefixedsteady

USINGFIXEDANDTRAVELLINGSTEADIES

The fixedsteady isusedmainly to turn theendofabaror tocentre a workpiece that is too large to fit through the chuckObviously bar stock should not protrude from the chuckmorethan is necessary to work on This is where the fixed steadycomesinThefixedsteadycanbesettothediameterofthebarsothattheendofthebarcanbemachinedsafely

Thesteadycanbesetusingachuckmountedonthistailstockadaptor

Travellingsteady

Settingthesteadybyusingachuckmountedonanadaptor

Onewaytosetthefixedsteadytosizeistoturnabitofbarin the chuck to the same size as the barwewant to use thesteadyonThenwecanmovethefixedsteadyalongthelathebedandfittheworkpieceintothechuckandinthesteadyTheendof thebar nearest to the tailstock shouldnowbe runningtrueandcanbeworkedonsafelyThebarcanbecentredrilledfacedorotherwiseworkedonAn alternative way to set the steady is to support the

tailstockendof thebarwitha threejawchuckmounted in thetailstockAdaptors to take the threejawchuckareavailableoryoucouldmakeyourownJustsupportthebaratbothendsinthethreejawchucksandsetthesteadyfingerstothebarThe fixed steadycanalsobeused to support tubes thatdo

nothaveanymaterialinthecentreThe fingers of the steady need to be lubricated regularly

while inuseThis iseasilydonebydrillinga smallhole in thetopfingerwithacountersinkinsidetheslottotakeoilThetravellingsteady ismostoftenusedwhenturningdown

small diameterbarsor screwcutting long slenderbars It boltsonto the front of the cross slide in line with the chuck and

travelsalongwhenthecrossslideismovedalongthelathebedWhen turning the travelling steady can either be set to thediameterofthebarbeforeturningandtoleadthetooloritcanbesettothefinisheddiameterrequiredandtofollowthetoolNormallythefingersaresetto leadtheturningtoolbut if thebarisroughforexampleifitisdentedorrustyitisbetterforthefingerstotrailtheturningtoolIfscrewcuttingthetravellingsteadyshould lead the toolso that itdoesnotdeflectorwearduetoaburrbeingthrownupbythescrewcuttingtoolSteadies will not be used very often but they are

indispensableontheoccasionswhentheyareneeded

Travellingsteadywithleadingfingers

Travellingsteadywithtrailingfingers

MAKINGASIMPLEFORMTOOL

Youmay often need to produce a particular shape such as aradiusonacomponentTheeasiestmethodtodothisiswithaformtoolAsanexamplewewillmakeasimpleformtooltocutahalfcircleonabarofbrassForaradiusof3mmforexampleweneedtoproducea formtoolusinga6mmdiameterdrillorreamFormaterialwewillusegaugeplateahighcarbonsteelthatcomesintheformofagroundflatbarApieceabout5mmthick and10mmwide is needed although the size is not thatimportantaslongasthegaugeplateisthickenoughtoabsorbanyturningstressesIdeallyweneedataperedreamerthatwillproduce a 6mm diameter hole somewhere along its lengthalthough you could use a parallel 6mm reamer a slot drill orendmillorevenastandardtwistdrillDrill a hole through the gauge plate and open up to 6mm

diameterAim togetagoodsurface finishon thesidesof thehole Hacksaw and file half the hole away to leave the shaperequired on the finish turned component Now we need to

harden the tool although ifweare justdoingacomponentortwoinbrasswecouldprobablygetawaywithouthardeningitHardeningissimpleenoughheattheworkingendofthetool

toredstopheatingandletthegaugeplaterestforacoupleofminutesThiswillgive thegaugeplateachance tochange itsinternalstructureReheattoredandquenchinatubofwaterThisshouldhardenthetoolAlthoughabitbrittle itshouldbefine for making a few components Stone the top of the tooluntil thecuttingedge issharp Ifnecessaryyoucanpolishtheinside of the radius that is going to do the cutting There areseveralmethodsyoucanuse includingapieceofwetanddrypaperaroundabitofbaraverysmallgrindingwheelcalledamounted point or a bit of round bar with fine valve grindingcompoundonitWhicheveryouuseaimforapolishedfinishasthe finish on the turned component is directly related to thefinish on the form tool You canmakeall sorts of simple formtools with gauge plate a typical example being a facing toolwitha30-degreechamfertofaceandchamfernuts

CopytemplatereadytouseMetal

MachiningfromaTemplate

MachiningfromaTemplate

YoucanmachineaprofilefromasimpletemplateThetemplatecanbecutfromgaugeplatewithafileormachinedbutitdoesnot need to be hardened The template could be used tomachinea large radius suchasa smokeboxdoor Inuse thetemplateismountedonablockonthelathebedandthecrossslide is kept in contact with the template by being pushedagainstthetemplatewithaballracefixedtothecrossslideInthenextchapterwewillbelookingatdrillingandreaming

9DrillingandReaming

ThischapterexplainshowtousedrillsandreamersinthelatheTherearemanydifferenttypesofdrillsandreamersTheyareessentialtomakingcomponentsinthelatheWewilllookatthevarioustypesandhowtochoosethespeedsandfeedsforusingthem

Thisdrillchuckrequiresachuckkey

TYPESOFDRILL

Drills are normally held either in the tailstock if they have aMorsetaperor inadrillchuckiftheyhaveaparallelshankA

drillchuckismountedonaMorsetapershankthatisusuallythelargestMorsetaperthatthetailstockwilltakeThelargestsizeof drill that will normally fit a drill chuck is frac12in (13mm) indiameter although larger chucks are available at a cost Thesmallest sizeofdrill thatafrac12in (13mm)drill chuckwill take isusually about 116in (15mm) This is because the larger drillchuck is incapableofclosingdownenoughto take thesmallersizesofdrillThismeanswewillprobablyneedtwodrillchucksoneforlargerdrillsandoneforsmallerdrills

Hand-tighteningdrillchuck

TherearetwomaintypesofdrillchuckOneistightenedbyusinga chuckkeywhichhasa small bevelgearbuilt on to itthatmates with the outer sleeve of the drill chuck itself Theother type is hand tightenedwhere the outer chuck sleeve isknurledtotightenthedrillthesleeveisturnedbyhandLargerdrillsabovefrac12in(13mm)usuallyhaveaNo1orNo2

MorsetapershankYoucangetMorsetapersleevestoconvertalargeMorsetoasmallerMorsetaperYoucanalsogetasmallMorsetolargeMorsetaperconverteraswell

Drillwithataperedshank

Some larger drills are also available with parallel shanksTheyaremadewithasteppeddownfrac12inparallelshankandarecalledblacksmithrsquosdrills

Blacksmithrsquosdrill

Themostusefuldrills in theworkshopcomeassetsofhighspeedsteeljobberdrillsinacaseThemostpopularsetcovers1mmto6mm increasingby01mmstepsAnotheruseful setcoversfrom6mmto10mmalsoincreasingby01mmstepsIfyouareintomodelengineeringasetofnumberdrillsfromNo1toNo60istoberecommended

Asetofmetricdrillscovering1ndash6mm

Drills are also available in different lengths Stub drills areshorter than standard jobber drills Several lengths of longseries drills are also available ranging from one and a halftimesthelengthofajobberdrilluptoseveraltimesthelength

Differentlengthsofdrills

Mostdrillshavetwoflutesbutcoredrillsarealsotobehadwith three four or evenmore flutes As their name suggeststhese are usually used for drilling out cored holes in castings

CoredrillsarenotnormallycapableofstartinganewholebutareusedforopeningupexistingholesAstandarddrillusuallyhasanincludedangleof118degrees

Stub drills and cobalt drills often have a 135 to 140 degreeangle for use on hardermaterials such as stainless steel andaircraftsteelsBack rakeondrills is oftenground radially Another typeof

pointhoweverhasfourfacetstothepointFour-facetdrillsaremuch better at starting a hole than a standard jobber drillwhich tends towanderunless followingacentrepoporcentredrill Four-facet drills also require less pressure to drill a holesincethepointisthinnerthanastandarddrillandtheyarefareasier to sharpen accurately by hand than standard jobberdrillsDormerdoarangeoffour-facetdrillscalledA002withatitaniumnitridecoating(TiN)andafour-facetpoint

Three-flutecoredrill

DormerA002four-facetdrillpoint

To drill an accurate sized hole requires two ormore stepsfirst youdrill the hole undersize (by perhapsfrac12mm) then youfollowthroughwithasizedrillThechancesaretheseconddrillwillcutdeadtosizeasitisonlycuttingasmallamountfromthediameter Obviously if you are drilling a large hole moreintermediatestepsmayberequiredSpeedsfordrillingarethesameasthosegivenforturninginthetableinChapter3

Setofcentredrills

REAMERS

There are several types of reamers available for use inworkshops again with either Morse taper or parallel shanksSomehavesizeparallelshankstheshankbeingthesamesizeas the reamer while others are availablewith shanks smallerthanthereamedsizeThereisalsothewaistedreamerwheretheshankisthesamesizeasthereamerthemiddleissmaller(waisted)andthecuttingendistheholesizeYoucanalsogetadjustablereamerswheretheendisexpandedbytheuseofascrewinthecuttingendofthereamer

Handreamerthefrontparthasaslighttaper

Straightshankmachinereamer

Waistedshankmachinereamer

Morsetapershankmachinereamer

Parallelreamersaredividedintotwotypesparallelmachinereamerswhere thecuttingdiameter is thesameallalong theream and hand reamers where the cutting end is slightlysmallerandtapersuptothefulldiameterWhen drilling a hole for reaming it is advisable to use the

two-holemethodfordrillingYouaremore likelytogetagoodsize hole prior to reaming For small reamers up to 04in(10mm) leave about 0012in (03mm) for the reamer toremoveForreamersuptofrac34in(19mm)leave0016in(04mm)and over frac12in (13mm) leave 0020in (05mm) For reamingspeedsuseabouta third toahalfof thedrillingspeed for thesamediameterFeedsshouldbefrom0002to0004in(0025ndash005mm)per toothper revMultiply the feedper toothby thenumberofteethtogivethefeedperrevolutionItisbesttouseneatcuttingoilformostmaterialsexceptfor

aluminiumforwhichparaffinshouldbeusedandplasticwhichrequirescompressedairorplainwaterYoushouldnotuseoilasacuttinglubricantforanytypeofplasticasitcanattackandordegradetheplastic

10BoringToolsandBoringHeads

Thischaptershowsyouhowtoboreholesinthelathewiththeworkheldinachuckmountedonthefaceplateorfixedtothelathecrossslide

TypicalHSSboringbar

DIFFERENTTYPESOFBORINGBARS

BoringaholetosizeisoneofthemostexactingjobsyoucandoinalatheItisrelativelyeasytoturnashafttofitaholebutitis much harder to bore an accurate hole to fit a shaft Ifpossibleyoushouldboretheholebeforeturningtheshaft

YouarelikelytocomeacrossHSSboringbarsorinsertedtipboringbarsBothhavetheirusesTheHSStoolisidealformostgeneralhole-boringjobsbuttheinsertedtiptoolisfarsuperiorfor materials such as cast iron The boring bar should be aslargeasyoucangetintotheholewhilestillallowingswarftoberemovedTheboringbarshouldonlyprotrudefarenoughtoenableitto

go completely through the bore Any more protrusion than isnecessarymay result in chatter or a dig in in the bore Thefront clearance on the boring bar tip should be as small aspossiblewithoutrubbingasstrengthisimportantBoringcanbeusedtofinishaholetosizeorsimplytotruea

holeupafterdrillingandpriortoreaming It isbesttoruntheboringtoolthroughtheholeusingafinefeedtothecarriageifyouhave the feedoptiononyour latheThe final finishingcutshouldbeputthroughtwoorthreetimesatthesamesettingtoeliminateanyspringinthetoolworkorlatheIftheholehasanintermittentcutthroughitsuchasacrossholetheholeisbestboredtosizeIt ispossible toborequite smallholes if youhave the right

tool Commercial lsquosmall holersquo boring tools are very expensivebut Ibuythemsecond-handwhenever Iseethemso Iusuallyhave a stock It is easy if time consuming to grind up smallboringbarsbuttheyareveryusefulespeciallywhenyouneedtotrueupasmallholepriortotappingorreamingEndmillsandslotdrillsmakeusefulboringtoolsAs longas

yougetthecuttingedgeoncentreheighttheywillboreaswellasaproperboringbarespeciallyinaluminiumYoucanmakesimplehome-madeboringtoolsbydrillingand

reamingaholetotakeaHSStoolbitintoasteelshankIdeallythe shank should be made of high tensile material or silversteelThetoolbitshouldbesecuredwithahightensilesocket-headedgrub screwor similar The tool bit caneitherprotrudefromthesideoftheboringbarforthroughholesorprotrudeatthe frontof theshankat45degrees ifyouareboringablindholeRoundboringbarscaneitherbeclampedintotheVeegroove

foundinsometoolholdersorheldinasplitsquareshankEithermethodissuitableespeciallyastheshankcanbeslidinoroutofthetoolholdertominimizeprotrusionSpeciallyshapedtoolbitscanbeusedtoundercuttheendof

the borewhen it needs to be screwcut and canrsquot be cut rightthrough Inserted HSS boring bars can also be ground up forundercuttingbeforescrewcuttingThereareseveralmethodsofcheckingaboreforaccuracyIf

youhavetoboretheholetofitanexistingcomponentperhapsaballraceyoucanuse theexistingcomponentasagaugeorturnupagaugeRoughout theborewithina few thouof thefinishedsize taking twoor threespringcutsUsea telescopicgaugeapairofcalliperswithamicrometeroradigitalverniertomeasuretheholeBorethestartoftheholebynomorethanonethouata timedonotgoright throughtheboreTest thefrontoftheboreifthegaugedoesnotgointotheborerunthetool right throughunderpower feedBoreout the frontof theholebyanotherthouchecktheboreandrepeatuntilthegaugejustgoesintothestartoftheholeFinishtheboreatthesamesetting checking that the gauge just enters Take a couple ofspringcutstoensuretheboreisparallelYoushouldnowhaveanaccuratelysizedholeThe trick to boring is to finish with very fine cuts Many

engineersdonotrecommendfinecutsbutIhaveneverhadaproblemaslongasthetoolissharp

Asetoftelescopicgaugesforcheckingaboreusedinconjunctionwithamicrometer

Checkingaborewithahome-madegaugeTheleadinisonethousmallerthantheborerequired

USINGABORINGHEADINTHELATHE

AnothermethodofboringacomponentinthelatheistoboltitdowntothecrossslideWhentheworkpieceisbolteddownandtheholeposition is linedupwith theheadstock youcanboretheholeintheworkpieceinseveralwaysFirst however you might need to put a hole into the

workpiece to clear the centre of the hole out of theway Youcandothisbyusingadrillinathree-orfour-jawchuck(smallerdrillscouldbeusedinadrillchuck)Startwithasmalldrillandworkupalmosttothefinishedsizeoftheholetobebored

Boringaholereadyforreaming

Toboretheholethefirstoptionistoholdaboringbarinthethree-jaw chuck This is a good basic method of boring aworkpieceonthecrossslideTheonlyawkwardbitisadjustingtheboringbarsothatasizeholeisboredThisisusuallydonebyanadjustingscrewpressingontothebackofthetipoppositethe cutting edge The tip itself is usually clamped by a grubscrewthroughthesideoftheboringbarHoweveryoucanuseaboringbarthatisafewthouundertherequiredsizeandfinishoffwithareamerA similar way that is easier to adjust is to use the same

boringbar in the independent four-jawchuckThen insteadofadjusting the tip in the boring bar you can adjust the entireboringbar inthefour-jawchuckThisasyoucanimaginewillbealoteasierthantryingtoadjustthetipintheboringbarThethirdmethodofboringworkonthecrossslideistousea

properboringheadThis iseasy toadjustas it isdesigned forthisverypurposeFinallyyoucouldusea lsquobetweencentresrsquoboringbarwhich

isheldbetweentheheadstockandtailstockcentresThisistheonly option when you are doing a long bore such as a largecylindercastingforalocomotiveortractionengine

Boringtheholeusingthefour-jawchuckmethod

Usingtheboringheadinthelathemandrel

Unlike when you are facing and boring a component in achuck you will not be able to face across the front of thecomponent (Boring heads with the ability to face across theworkareavailablebutareunlikelytobefoundintheamateurrsquosworkshop) Thismeans you will have to face across the workwith a flycutter in order to keep the face true with the boreFlycutters are available quite cheaply or you couldmake yourownandholditinthefour-jawchuck

Aflycuttersuitableforfacingthefrontofacomponentthathaspreviouslybeenboredonthe

crossslide

11KnurlingRadiusTurningandProductionMethods

This chapter explains how to use knurling tools and radiusturningtoolsaswellasusingbasicproductionmethods

KNURLING

Knurlingistheprocessofformingorimpressingapatternonapiece of metal often for the purpose of making a grip for apieceofequipmentsuchasaknobBothstraightanddiamondknurlscanbeproduceddependingonthetypeofknurlyouareusing Diamond knurling is usually done with two knurlingwheelsalthoughsingle-wheeldiamondknurlsareavailableKnurls are also available in fine medium and coarse sizes

although the size is relative fromdifferentmakers The speedfor knurling is usually about half of the turning speed for thesame diameter bar Normal knurling is of the male patternwheretheknurlingconsistsofraisedpyramidsFemaleknurlingismuchrarerandconsistsofdepressedpyramidsThere are threemain types of knurling tool but only two of

these are found in the average workshop The first type ofknurling tool is the so-called lsquocutrsquo knurling toolwhichactuallycutsaknurlratherthanpressestheknurlintotheworkThisisaspecialized tool more often used in industry and is veryexpensivesoitisnotfoundinmanyhomeworkshops

lsquoBumprsquoKnurling

The most common knurl is the single-or double-wheel knurlsometimes called a lsquobumprsquo knurling tool The wheels aremountedat the frontof the tool This typeof knurl is pressedintotheworkbyusingthecrossslideandcanproduceagoodqualityknurlHowever itdoesputveryheavypressureonthemandrelandlathebearings

Acommerciallyavailablestraddleknurlingtool

StraddleKnurling

Thebest typeofknurl foroccasionaluse is thestraddleknurlwhich has two knurling wheels that completely straddle theworkpieceThistypeofknurldoesnotputastrainonthelathebearings and so is preferred bymost lathe users (Two-wheelknurlingtoolsareavailablethatresemblestraddleknurlingtoolsbut they donrsquot open up to take anything more than smalldiameters relying on pressure at the side of the job like alsquobumprsquoknurl)To set the straddle knurl up wind the tool against a bit of

plateheldontothesideofthebarRemovetheplateandmovethetoolinbythethicknessoftheplatehalftheknurldiameterandhalfthebardiameterThiswillputthetoolontothecentrelineofthebar

Settingtheknurlingtool

In use set the knurling wheels to the centre as describedabove wind the knurls onto the outside diameter of the barwindtheknurlawayfromthebarandmovetheknurlingwheelsclosertogetherbytwicethedepthoftheknurlpatternSwitchthelatheonandwindthetoolbackontothecentrelineandthetool should start to form the knurl You can now traverse theknurlingtoolalongtheworkpieceto formtheknurl remembertousecuttingoilNote that theknurlsshouldhavechamferedsidesifyouaretraversingalongtheworkpieceYouneedtogodeepenoughsotheknurlisfullyformedbut

notsodeepastodeformtheknurlBecausetheknurlstraddlestheworktheknurlsstartoff independentlyandmaynotbe inalignment around the diameter Once you start moving theknurlingtoolbackwardsandforwardsalongtheworkhoweverthetoolshouldlineitselfupThismeansyoumayhavetoturndownorpartoffthebarwhereyoustartedtheknurlIfyougotoodeepespeciallyinaluminiumthewholedepth

ofknurlcouldgetdestroyedandevendropoff theparentbarThis is called flakingKnurling isnotadifficultprocessa littlepracticewillsoonhaveyouknurlinglikeaprofessionalengineer

Anaccomplishedbitofknurling

AformtoolcuttingaballTheinsetviewshowstheformtoolandafinishedball

RADIUSTURNING

Sometimesweneedtoformanexternalradiusontheendofabit of bar perhaps for a ball-shaped handle We can use asimple lathe attachment to do this Basically the attachment

consists of a short turning tool mounted onto a U-shapedcomponent that is arranged to pivot on another U-shapedcomponentheldinthelathetoolpostBy pivoting the attachment back and forth a radiuswill be

generatedForatrueradiusthepivotpointshouldbesetonthecentrelineofthebarTheradiusgeneratedwilldependonhowfarthetoolbitissetbackfromthecentrelineoftheworkpieceTosetthetoolupwindtheattachmentuptoaplateheldto

the sideof thebar youareworkingon remove theplate andwindinthewidthoftheplatehalfthewidthofthebarandthewidthofthefixturetothecentrelineofthepinThiswillputthepivotonthecentrelineThenyoucansetthetooltotheoutsidediameterofthebarThiswillproduceaballthesamediameterasthebarTo turnan internaldiameteruse the samemethodbut the

turning tool will need to pass through the centre of the pivotand out the other side You will be limited to shallowdepressionsratherthanlargesemicirclesbutthistechniquecanstillbeusefulonoccasionThealternativemethodof formingaball iswithaball form

tool

Astopbarblockforthecarriagestop

PRODUCTIONMETHODS

PRODUCTIONMETHODS

Foreaseofproductionthefirstthingyouneedtouseisabedstop (see Chapter 5) The chances are that you will need tomakeyourownTheoneIuseisveryversatileandconsistsofablockmountedatthefrontofthelatheheadstocktogetherwitharodtoactasthestopDependinguponwhatyouaredoingitmaybeusefultohave

morethanonestopbareachwithitsownseparatestopblockInusethebarisinsertedintothemainblockasfarasthestopblock(if fitted)andlockedinplaceThefirststopbarcouldbeusedto facetheworkpieceandthesecond(shorterbar)couldbe used to turn along the diameter while a third bar couldpositionthepartingofftoolAnalternativeadditiontothestopbarcouldbeawasher(orwashers)ofknownthicknessplacingthewasher(orwashers)onthebarwillextendthestoppositionbythethicknessofthewashersusedAusefultipistostampanumberonthestopblockssothat

eachone isnumberedYoucouldalso stamp the thicknessonthewasherssoyoudonrsquothavetokeepmeasuringthemandjustpickthemupinthecorrectorderItsavesalittletimeandhelpsavoiderrorsThe whole point about using a stop is the consistency of

positionwhichistransferredtotheaccuracyofthecomponentit gives Once you have learnt to use a stop youwill wonderhowyoumanagedwithoutitEvenforone-offcomponentsitwillsaveyoutimeForatypicalone-offsteppedshaftsetthestopsotheturning

tooljustfacesthebarandfaceoffMove the top slide along for the length of the turned step

requiredTurnthestepYounowhaveastepontheendofthebarofaknownlengthNofiddlingnomeasuringndashyouknowitiscorrectUsing the bed stop offers a simple way of doing repeat

turning of lengths and diameters in the lathe Stops are notlimited to production methods they are very useful formachiningone-offsaswell

A single stop bar will serve for much of the work you aredoingbutsometimesyouneedmorethanonestopTheanswerhereistousemorethanonestopbarinconjunctionwithastopblockEachbarhasitsownstopblockthatcanbetightenedupThenyoucaninterchangethestopbarsandeachbarcanbesettotherequiredlengthbyusingavernierorruleYoujustsetthetwostopblockstothedifferencerequiredandlockthestopbarintheholderasnormalWhenyouneedmorethanoneofeachitemitisveryeasyto

save time in theworkshop once the lathe is set up you canmake several items in quick succession A typical example ofthis type of production is a simple spacer Set a facing andchamferingtoolinonetoolholderapartingofftoolinanothertoolholderandadrillinthetailstockchuckThefacingtoolandparting off tool are in fixed positions to each other so it is asimplematter of drilling thehole facingoffwithone tool andparting off with the other As long as the gap between thepartingofftoolandthefacingtoolremainsconstantthespacerswill remain at the samewidth each time youmachine one ofthemTheeasywaytosetthethicknessofthewasheristofaceoff

theendofthebarbringthepartingofftooluptothefinishedface and lock the cross slide Wind the parting off tool backslightly so you can move the bar forward in the chuckMeasuring with the vernier calliperrsquos depth rod from therighthandfaceofthepartingofftoolbringthebaroutslightlylonger than is needed for the washer thickness Using thetailstock chuck drill the hole using a centre drill for the firstwashertoensurethedrill runstrueNowsetthefacingtool inpositionfaceoffthewasherandpartofffromthebarMeasurethe washer and adjust the facing tool either way so that thethicknessof thewasher iscorrectPull thebar fromthechuckslightlyfurtherthanthefacingtoolsothateachwashercanbefaced to lengthYoucanmakeasmanywashersasyouneedall of the same thickness The same applies to nuts and anyothercomponentthatneedstobeasetlengthIfmakingboltsor screws theprinciple is thesamebutyou

willneed to turndown thediameter tobe threadedThis timethedifferencebetweenthepartingofftoolandtheturningtoolisthethicknessoftheheadInordertofacetolengthhoweverawasher of a known sizemust be inserted between the stopblockandthecrossslideThiswasherwillbethelengthoftheturneddownportionofthecomponentIfyouwanttomakeabatchofcomponentsbutdonrsquotwantto

keepmovingorchangingtoolsyoucanmachinethebatchonestepata timedoingoneoperationoneachcomponentbeforedoing the next operation on all the components Repeat thisuntil the complete batch ends up as completed componentsYou have the added advantage that the components willprobablyallbethesameshapeandsizesomethingthatisnotalwayspossiblewhenmachiningeachcomponentindividuallyTo make a batch of components such as washers to the

samethicknessisquitesimpleSetupapartingtooltopartoffthe components and set up a facing tool to face thecomponentsThedifferenceinpositionbetweenthefacingtooland the parting toolwill be the thickness of thewashers Youcanadjustthethicknessofthewasherbymovingthefacingtoolbackwardsor forwardswith the topslide toadjust it The rearpartingofftooldoesnotmoveotherthantopartoffthewasher

Makingwasherstothesamelengthusingfixedpositiontools

TAILSTOCKTURRET

AnotherusefulaccessoryisthetailstockturretThisisarotatingheadthatisusuallysetbackatanangleItfitsintothetailstockof the lathe and has multiple stations to take different toolsoftenitwilltakefourfiveorsixtoolsThebenefitofthisisthatitcanhaveabarendstopacentredrilladrillacountersinkatapandadieoranycombinationthereofallsetupreadytousein sequence The tools normally fit into holes bored into theturretToavoidtoolsstickingouttoofar it isbesttousestubdrillsinsertedintoroundbarsthatfitintotheturret

Anindexingturretthatfitsdirectlyintothetailstockofthelathe

YoucaneitherdrillandtaptheroundbarsoruseLoctite tosecure the drill in the round bar You can also buy roundadaptorswithaJacobschucktapermachinedontheendtotakechucksAnothermethodoffittingchucksistodrillandtaptheround bar to take chucks with threaded extensions ThesechuckscanoftenberetrievedfrombrokenBlackampDeckertypedrillsDieholderscanslideonapieceofroundrodintheturretFor

smaller diameter threads you can stop the die from rotatingusing your hand There is no need to reverse the lathe whenthreading just stop it and spin the die off by hand the samegoes for taps For larger taps and dies you can use a shorttommybartostoprotationbutmakesurethatthetommybarpositionisclosertotheworkthantheendofanyofthedrillsorthetommybarwillsnapthedrillsifyouletgoofitorifthetapordiejamsupYoucanalsomakeorbuyarunningcentretofitintotheturrettosaveremovingitwhenyouneedtousealathecentreOnlydothiswithsmallorlightworknotheavybarsorfor largecutsWhenused inconjunctionwithagoodbedstop

system a tailstock turret becomes a very versatile productionfacilityTheturretcanbemademoreversatilebyfittingalever-feed

tailstockattachmentoracapstan-style feedattachmenttothetailstockturretEitheroftheseattachmentswillmaketheturretveryfastinoperation

Anindexingturretsetupwithastopandacentredrill

Standardlever-feedtailstock

SECONDOPERATIONWORK

SECONDOPERATIONWORK

Sometimes it is necessary to do second operation work on apart-machinedcomponentUsually thiswillbeon theoppositeend to the one already turned There are two main ways ofholding theworkpiece in the correct position for furtherworkthechuckbackstopandsoftchuckjawsThechuckbackstopisquitesimpletomakeItconsistsofa

draw-incolletapieceofplainbarforthestopabitofthreadedbar a nut and a top hat collar The collet goes into the lathemandrelandisdrawninbythethreadedbarThethreadedbargoesthroughthemandrelandislockedinplacebythenutandthe tophatcollarat the left-handendThe tophatcollar is toprotecttheendofthemandrelThestopbarfitsthecolletandispositionedsothattheworkislocatedattherightdepthinthechuckThismeansthateachcomponentput intothechuckupagainstthebackstopwillalwaysbeheldinthesameposition

Capstan-stylelever-feedtailstock

Adraw-inbackstop

Softjawswithhexagonsadded

The secondmethod is to hold the component in soft jawswhich are bored out to hold the component (see Chapter 5)ThismeansthecomponentshouldrundeadtrueandeachonewillbeheldinthesamepositionreadytobemachinedSoft jaws tend to be used for larger components while the

backstop ismore likely tobeused forbarworkYoucanboltextension pieces to soft jaws to hold larger diameters orextensions can be machined to make a nest to take largercomponentsWhensoft jawsarewornoutandfaceddowntoo

lowforfurtheruseyoucanboltapieceofhexagonbartoeachjawtogivethemanewleaseoflifeIfyouhaveabatchofthreadedcomponentstofinishonthe

second end you can screw them into a bit of bar held in thechuck If theyarehexagonbolts just tightenup lightlywithaspanneriftheyareroundheadandtheheadwillbemachinedlateryoucouldtightenanduntightenthemwithapairofpliersThe more production work you do the more varied the

methods you will learn and the quicker you will makecomponentstoahighstandardofaccuracyA sensitive drilling attachment can be very useful when

drillingwith tiny drills The feed is by hand which gives it itssensitivity The attachment can also be used for small tapswherethetravelisfairlyshort

Machiningscrewheadsbyholdingthescrewinathreadedmandrel

Asensitivedrillingattachmentthatfitsintothe

tailstockchuck

ThisVeeattachmentisusedforcrossdrillingandcanbeusedintheheadstockorthetailstockofthelathedependingonthelengthofthebartobecrossdrilled

ThisisarevolvingtaperforthetailstockIfyoufitadrillchucktoityoucanuseitasarunningsupportforsmallbarwhereacentreisnotpermissible

12TapsDiesandScrewcutting

Thischaptershowshowtousetapsanddiestocutinternalandexternal threads in the lathe Italsoexplainshowyoucansetupasimplegeartrainandcutascrewthreadwiththehelpofascrewcuttingdialindicator

Atypicaldie

CUTTINGTHREADS

Threadcuttingeither internalorexternal isan importantpartoflearningtousealatheThepurposeofathreadisusuallysothatyouareabletoholdpartstogetheralthoughotherusesforthreadssuchasleadscrewsandfeedscrewsformachinetoolsareoftencalledfor

Safetyhasalreadybeencoveredindepth(seeChapter2)butafewextrawordsonsafetywhenthreadcuttingarecalledforWhen tapping a hole or threading a bar from the tailstock atailstocktapordieholderisoftenusedForthesmallerthreadstheholdershaveaknurledbodyandrotationcanbestoppedbysimplyholdingthebodyoftheholderinyourhandAslongasyoukeepyourhandawayfromthechuckandany

sharp lathe tools on the cross slide you should be fine (ifpossible remove either the tool holder or the tool itself )Providedthereisnothingtocatchorsquashyourhandonyoucan hold the knurled tap or die holder in your handwhile thelathe is running slowly under power and releasing the holderwhen the full length of the thread is cut or the pressurebecomes too great for you to stop the rotation (By slowly Imeaninveryslowbackgear)For largerthreadshoweveratommybarwilloftenneedto

beusedtostopthetapordieholderfromrotatingWhenusingthe tommy bar to prevent rotation do not under anycircumstances use the lathe under power Instead switch themachinerightoffandunplugit ifpossibleTurnthetapordieholdingthetommybarwiththerighthandandstopthechuckfromrotatingwiththelefthandThere are already many published charts providing thread

data covering such factors as tapping hole sizes minimummaximum and effective diameters as well as pitches andthreadsperinchIwillnotbeprovidingthemherebutwishtopoint out that tapping size drills can vary with the materialbeingcutWhenIamtappingsmallsizes instainlesssteel forexampleIusuallydrillthehole0004in(01mm)largerthanthefigurestated in thechartThisway Iam less likely tobreakatapinthehole

HSSorCarbonSteel

TapsanddiesareusuallymadefromcarbonsteelorHSSHSStapsanddiestendtoremainsharpformuchlongerthancarbonsteeltapsbutcarbonsteelisusuallycheaperNewcarbonsteel

tapsanddieswillprobablybefineforsmallerholesandsoftermaterials but wherever possible HSS should be your firstchoice Second-hand taps and dies are sometimes availablefromtoolshopsoroneBaybutinmyexperiencetheyareoftenbluntandnotworthbotheringwith

Lubricants

Whether tapping threading with a die or screwcutting it isnormallyessentialtousealubricantevenonbrassForbrassaluminium and bronze kerosene (paraffin) or white spirit isgenerallyusedandcanwithadvantagehaveasmallamountofcuttingoiladdedFor steel and stainless steel amodernpaste-based tapping

compound or cutting oil should be used This can also beappliedtocopperthismetalcanbestickybuttakeiteasyandall should gowell I also use paste or cutting oil on cast ironAlthoughmostrecommendationsaretocutcastirondryIhavefoundalubricanttobeveryhelpful

Screwthreadpitchgauge

ThreadGauges

When following a published design you will probably use thethread sizes as recommended by the designer If you are

making a thread to match an existing thread however youneedtofigureoutwhattheexistingthreadisThisiseasiesttodoonanexternalthreadIfyouhaveonlythenuttrytofindaboltthatwillfititandusethattocheckthethreadIfyoucanrsquotfindamatchingboltandtheholeinthenutisbigenoughyoucouldtrypressingabitofplasticineintotheinternalthreadandmeasuringthatTomeasuretheexternalthreadweneedtodeterminethree

thingsusingathreadpitchgauge theoutsidediameterof thethread the pitch of the thread and the thread angle Thesethree checks will probably be sufficient to decide what thethreadactuallyisBritish threads such as British Standard Fine and British

Standard Whitworth and also the Model Engineer threadsystemhaveanangleof55degreesAmerican threads such as UNF (Unified Fine) UNC (Unified

Coarse) UNEF (Unified Extra Fine) ANF (American NationalFine)ANC(AmericanNationalCoarse)are60degreesasisISOmetricUnusually theBritishStandardCycle thread is also60degreesThe other thread youmight come across is the BA (British

Association)threadThishasathreadangleof47frac12degreesandismetricbasedThelargestBAthreadis0BAwhichhasa6mmdiameterwith a 1mmpitch TheBA series godown to 22BAbutinpracticeyouareunlikelytocomeacrossanythingsmallerthanabout14BA

TAPS

TappingistheprocessofcuttinganinternalthreadwithatapFirst a hole is centre drilled and drilled in the workpiece Irecommend that you give the top of the hole a 90-degreecountersinktogivealead-intothetapandalsotostopthetapfromthrowingupaburrontothefaceofthework

Setofhandtaps

TypesofTap

The many types of tap can be divided into hand taps andmachinetapsHandtapsarenormallyheldinatapwrenchbutcan be held in the lathersquos tailstock chuck or a purpose-madetailstocktapholder

Close-upofahandsecondtap

WhentappingbyhandstartthetapuntilitstartstobiteandgiveitanextraturnorsoReversethedirectionofthetapforaturn to break the chip Continue forward for a couple of turnsand then reverseasbeforeContinue todepthor through theworkpiece by continually tapping a couple of turns reversingandcontinuingforwardThisshouldclearthechipsandpreventthetapfrombreakingIfthetapgetshardtoturntakeitrightoutoftheholetoclearanyswarfaddsomemorelubricantandcontinuetappingA set of hand taps will normally comprise a taper tap a

secondtapandaplugtapUsuallyyouwillstartaholewithataper tap This is a tap where the outside of the thread isreducedtowardsthepointbygrindingitonataperThistypeoftap can be used to start the hole but if the hole goes rightthrough the work it may be possible to screw the tap rightthroughtheholesoformingafullthreadrightthroughIfthetapertapistooshortorifyouaretappingablindhole

youneedtofollowthetapertapwiththesecondtapwhichhasmuch lessofa taper In fact itonlytapersrightat thestartofthetapTheplugtapisfinallyusedusuallytofinishoffablindhole

Theplugtaphasnotaperonitjustashortlead-inontheendBetween the three you should be able to tap themajority ofholesintheworkshopWhentappingblindholesitisbesttoworkoutthedepthand

fromtherethenumberofturnsneededforthetaptoreachthebottomoftheholeAsanexamplesaytheholeis9mmdeeptothepointThe tapenters2mminto theholebeforestarting tocutSo9mmless2mmgives7mmThepitchofthetapis05mm7mmdividedby05equals14sothenumberofturnstothebottomoftheholeis14Inpractice12or13turnswillbethemaximumneededWhen tapping blind holes make sure that all swarf is

removedfromthebottomoftheholebeforestartingtotap

Selectionoftapholders

HoldingTaps

TherearetwomaintypesoftapwrenchthehandtapwrenchwhichisdesignedtobeheldwithbothhandsandtheTeetypetapwrenchwhichoncestartedcanoftenbeusedone-handedTapsusuallyhaveeitheracentreholedrilledintheshankor

theshankisgroundtoapointThismeanswecansupportthetapfromthetailstockeitherbyusingalathecentreorbyabitofbarinthetailstockchuckwithafemalecentreinitTeetypetapwrenchesoftenhaveafemalecentreintheendandcanbesupported on a running centreWhen the tap is supported bythe tailstock at one end and the hole in theworkpiece at the

otheritmustbeinlinewiththeholeintheworkpiece

Machinetap

MachineTaps

Themaintwotypesofmachinetaparethespiralpointandthespiral flute The spiral point pushes swarf downwards throughthe hole while the spiral flute pulls the swarf out of the holeSpiralflutetapsaremuchweakerthanspiralpointtapsandintheory should not be used for tapping by hand However inpractice you can often get away with hand tapping using aspiralpointtapifyouareverycarefulIneithercasethetapisdesigned for continuous rotation swarf being automaticallycleared so the regular reversal as with a hand tap is notnecessaryIf you are careful you can probably get away with using a

hand tap under power but only do this with a hand-held tapholderwhereyoucanquicklyletgoifthetapstartstostickYou can also getmachine taps thatwill cut a thread under

powerbyscrewingthroughthejobwithoutstopping

Spiralflutetap

SpeedsforTapping

Tappingspeedsshouldbe low lowbackgearspeedshouldbefineWhenyouhavetappedtheholetodepthorrightthroughtheworkpiecestopthelatheandspinthetapoutbyhandThiswillbequickerthanreversingthelathe

ThreadingfromtheTailstock

For small taps you can use the sensitive drilling attachment(seeChapter11)orifthetapislargeryoucoulduseaslidingtapholderThiscanbeassimpleasachuckmountedonataperat one endwith a parallel hole through the chuck shank ThechuckthenslidesonabarheldinthemaintailstockchuckForlargetapsyoucanuseatommybartostopthetapholderfromturningbutthetommybarshouldnotbesolongastofoulthelathebedoranyotherpartofthemachineifyouhavetoletgoInfactitisfarsaferifyoudonotusethetommybartothreadunderpower

DIES

Dies also come in carbon steel andHSS versions The outsidediameterofadieoftenvarieswiththesizeofthethreadbeingcutalthoughthediameterwillbetooneofasetstandardDiesusually have themakerrsquos name and the thread details on thefrontof thedieThis is theside that ispresented to theworkThediewill havea short lead-in if this isnot requiredon thefinishedthreadyoucanreversethedieanditwillcleanuptoashoulder

SlidingtapholderSlidingdieholdersarealsoavailable

When cutting a thread especially a small one it pays tomaketheinitiallengthofthreadlongerthanthatrequiredThisissoyouhaveabitat thefronttoplaywithtogetthethreadright Then you can part off the excess length leaving a goodthreadoftherequiredlengthDies are usually split so you can adjust them to cut a size

threadIdeallyyoushouldhaveadieholderforeachdiesoyoucansetthedietocutsizewithouthavingtoresetiteverytimeyouchangethedieThedieshouldbesetsothatitcutsasizethreadinonepassDie nuts are often hexagonal in shape They are used to

cleanupanexistingthreadthat isdamagednot tocutanewthreadfromscratchFor each thread you are going to cut you should make a

home-madegaugetappedwithyourowntapWhenyoucutthethreadanditfitsthisgaugeyoushouldthenhaveagoodbutnottightorloosethreadYoushoulduseatailstockdieholderwithaslidingbodywhen

threadingfromthetailstockasthiswillholdthedietruetothethreadIdeally the tailstock die holder should be knurled and also

haveatommybarholeforeaseofuseThe speed for threading with a die in the lathe should be

quitelowamaximumof60rpmshouldbefineformostjobs

SCREWCUTTINGATHREAD

Whilecuttingathreadwithtapsanddiesisperfectlyadequatefor most applications the ability to cut an accurate screwthreadbyusingthelatheisaveryusefulfacilitytohaveIfthethread is large or non-standard taps and dies may not beavailable or they may be so expensive as to be out of thequestionforuseintheamateurrsquosworkshopVariouspitchesofthreadcanbecutbythesimpleexpedient

of changing the configuration of the change gears or alteringtheleversonthescrewcuttinggearboxifoneisfittedWewillconcentrate on a lathe with change gears if you have ascrewcutting gearbox please refer to the manufacturerrsquoshandbookMost lathes that youwill comeacross are likely to have an

imperialpitch leadscrewThiswillbeapitchofsomany teethper inch (TPI) Typically this will be 4 or 8 TPI although otherpitchesareavailableForourexamplewewillbeusingalathewithan8TPI leadscrewandasetofchangewheelscomprisingthefollowingnumbersofteeth2times202530353840455055606570and75

SETTINGUPTHECHANGEGEARS

Letrsquostakeatypicalthreadpitchof20TPIForeveryturnofthemandrel the leadscrew needs to move forward 120in Thismeans we have to set the change gears so the mandrel toleadscrewturnratio iscorrect Inpracticethemandrelgear islikely tobe20 teethand this is unlikely to change nomatterwhat thread we are cutting This means we will change theleadscrew gear which has to have the correct ratio to themandrelTheTPIwewishtocutis20usingaleadscrewwithapitchof

8TPI20dividedby8givesusaratioof251Thismeansthatthe mandrel gear needs to rotate at 25 times the leadscrewgearAsthemandrelhas20teeththeleadscrewgearneedstobe25times20teethwhichisa50toothgearInpracticea20toothgearanda50toothgearmaybetoosmalltotransferthedrive from the mandrel to the leadscrew and intermediategear(s)willneedtobeusedThese gears are called idler gears and they can have any

number of teeth Youmay think these idler gears change theratio of the mandrel to the leadscrew but they do not Theysimply transfer the drive from the mandrel gear to theleadscrew and the ratio stays the same This concept can behardtograspsoIwilltrytoexplainitsimplySay the mandrel gear does one turn This makes the idler

gearorgearsmoveexactly20teethandthisinturnmovestheleadscrewgearexactly20teethAsyoucanseetheratiodoesnotaltertheleadscrewgearmoves20teethforevery20teeththemandrelgearmovesandtheratiostaysthesameThistypeofset-upisknownasasimplegeartrain

Simplegeartrain

Compoundgeartrain

Letuslookatanothercommonthreadpitch32TPITheratioofleadscrewtoTPIis41(8times4=32)Sotheleadscrewgearneeds to be themandrel gear 20 teeth times 4 = 80 teethLookingattheavailablegearswedonrsquothavean80toothgearThismeanswewillhavetouseadifferentmethodtogetour41ratioWithamandrelgearof20teethwecouldusea40toothto

give us a ratio of 21 We are now halfway there but needanotherpairofgearswitha21ratioWedohavea30anda60

toothgearsothiswouldgiveusoursecond21ratioWecouldnot set these gears up as in the previous example howeversince the two intermediate gears would just act as idlers andtheratiowouldbe2150percentoutfromwhatisrequiredWhatwewouldhavetodoismountthe40toothandthe30

tooth gears on the same spindle so they rotate at the samespeedaseachother(The20toothgearmustdrivethe40toothgearandthe30toothgearmustdrivethe60toothgearinthisorder)Thiswouldgiveusthecorrect41ratiothatweneedAswehavemountedtwogearsononespindlethisisknownasasinglecompoundgeartrainDependingonyourlatheyoumayneedanidlergearbetweenthe30toothgearandthe60toothgearAgainthiswillnotalterthegearratiosYou can also have double compoundgear trainswhere two

lots of gears are mounted together on two spindles This istaking us into complicated territory however and I will referreaders to the screwcutting chart provided for their particularlathe Ifyour lathedoesnotcomewithascrewcuttingchartasearchon the Internet should findone that you candownloadandprintoutThemost likely application of double compound gear trains

would be to cutmetric threads with an imperial leadscrew orimperialthreadsover60TPII have tried to keep this explanation of setting up

screwcutting gears simple and the maths to a minimum Theexplanationgiventogetherwiththescrewcuttingchartforyourlatheshouldbemorethansufficienttogetyougoing

ExternalscrewthreadtoolmadefromaCoventry

diechaser

CUTTINGTHETHREAD

The speed for screwcutting should be about mid-back gear ifyouhaveitpreferablysomewherearound30ndash40rpmatmostTherearetwomainmethodsofscrewcuttinginthelatheThe

firstoneinvolvesthetopslidesetparalleltotheworkandintheothermethodthetopslideissetonanangletothework

Externalsinglepointscrewthreadtoolsettinggauge

Cuttinga20TPIThreadwiththeTopSlideParallel

For a 20 TPI Whitworth thread the pitch is 0050in and thethreaddepthisaconstant064ofthepitchsothethreaddepthis 0050 times 064 = 0032in This is the depth the cross slideshouldbewoundinWhilethedepthofthreadis0032inyoualsoneedtomove

the top slide forwardat eachpass Fora standardVee threadthisneedstobehalfthein-feedofthescrewcuttingtoolsoyoumovethecrossslideinby0010inandmovethetopslidealongbyhalfthis0005in

Cuttingascrewthreadwiththetopslidesetparalleltothelathe

Cuttingascrewthreadwiththetopslidesetatanangletothelathe

Theendresulta20TPIfinishedthreadbeforetidyinguptheendandundercutting

Cuttinga20TPIThreadwiththeTopSlideatanAngle

This angle will vary according to the thread being cut but itshouldbeabout1degree less thanhalf the includedangleofthethreadforaWhitworththreadof55degreesforexampletheangleshouldbehalfof55degreesminus1degreegiving265degreesNotethattheangleistakenwiththetopslidesetat90degreestotheworkWiththetopslidehandlefacingyou(at90degreestohowit isnormallyused)rotatethetopslidethe required number of degrees (265) to the right Beginnersoften rotate the top slide 265 degrees to the left from thenormalpositionwhichwouldgivean included threadangleof127degreesThisisclearlywrongBecausethetopslideissetonanangleyouwillneedtofeed

thetopslideinfurtherthanifthetopslideissetparalleltothelatheYoucan findthe increaseddepthof threadbyusingthefollowingformula

c=bcosineofA

whereAistheanglecalculatedathalftheincludedthreadangleminus1degreegiving265degreesb is thedepthof thread(forWhitworththreadsthisis064timesthepitch)andcisthecalculatedangulardepthofthreadFor a 20 TPIWhitworth thread the pitch is 0050in and the

threaddepthisaconstant064ofthepitchsothethreaddepthis0050times064=0032inThecompensateddepthofthreadisthen0032individedbythecosineof265degrees=00357

UsingtheThreadCuttingIndicator

With an 8 TPI leadscrew if the thread being cut has an evennumber of threads the leadscrew can be engaged at anypositionof the threadcuttingdial indicator If the thread isanoddnumberyoushouldusethesamenumberoranyalternatenumberthatisoneorthreetwoorfourForthreadswithahalfpitch always use the same number For metric threads orpeculiar numbers do not disengage the clasp nuts withdrawthescrewcuttingtoolandreversethemotoruntilthetoolgoesback to the start If the thread is an exact multiple of theleadscrewtheclaspnutscanbeengagedatanypositionIfindoubtalwaysengageatthesamenumberoneIttakes

verylittletimetotraversetheextradistancerequiredFor leadscrews other than 8 TPI please refer to your lathe

manual

AcknowledgementsandUsefulContacts

I would like to thankMy TimeMedia Ltd (Publishers ofModelEngineer and Model Engineersrsquo Workshop) Ken Wilson TonyJeffreeandTranswavePowerCapacitorsLtdfortheuseoftheirphotographs

USEFULCONTACTS

UnitedKingdom

ArcEuroTradeLtd10ArchdaleStreetSystonLeicesterLE71NATelephone01162695693Fax01162605805EmailinformationarceurotradecoukhttpwwwarceurotradecoukSuppliersofmachinetoolsandaccessories

ChesterMachineToolsHawardenIndustrialParkHawardenChesterCH53PZTelephone01244531631EmailsaleschestermachinetoolscomhttpwwwchestermachinetoolscomSuppliersofmachinetoolsandaccessories

CowellsSmallMachineToolsLtdTendringRoadLittleBentleyColchesterEssexCO78SH

Introduction

The lathe is often called the King ofmachine tools It is veryversatile and can be used to make all sorts of engineeringcomponentsHenryMaudslaywhomadehis first screwcuttingand metal-working lathe in England shortly before 1800 wasone of the first engineers to incorporate the slide rest aleadscrew and change gears into one machine This made itpossibletomakeinterchangeablescrewthreadswhichinturnrevolutionizedtheproductionofmachinesandmachinetoolsThis book is for you the practising or aspiring engineer

Whether you are working in an industrial environment or ahome workshop this book will help you to acquire importantnewskillsandgiveyouinsidertipsyouwonrsquotfindelsewherePerhapsyoudonrsquothaveaknowledgeablefriendtoteachyou

or you arenrsquot able to join a club It does not matter whatprevious experience you have this book will teach you thebasics of lathe work from first principles to advanced turningtechniques You will find all you need to know within thesepagesDuringmore than thirty years in the engineering industry I

haveworkedwithmanyengineersbothbeginnersandexpertsandhavetaughtmanyyoungpeopleduringtheirfirststepsintoengineeringWorkingasaself-employedengineerIlearntquickand accurate ways of working both frommy own experienceand from other engineers Since 2008 I have edited ModelEngineer and Model Engineersrsquo Workshop the two main UKmagazines formachining in the homeworkshop and this hasgiven me an insight into what amateur (and sometimesprofessional)engineersarelookingforIhavealsobeenabletoadvisemanyamateurengineersonhowtosolvetheirworkshopproblemsorjusttogetthemstartedontherightlines

ModelEngineersrsquoWorkshopintroducedin1990isarelativenewcomertothemodelengineeringsceneItdealsmainlywithtoolsandprocessesandisnowpublishedeveryfourweeks

ModelEngineerwhichcurrentlyappearseveryfortnighthasbeenpublishedcontinuouslysince1898Itismainlyaboutmakingprecisionmodelsbutoftenincludestechniquesforturninginthelathe

I would like to pass on some of this knowledge This bookMetal Turning on the Lathe is the first of three for CrowoodPressonaspectsofworkshopengineeringitwillbefollowedbyMilling and Introduction to Workshop Tools and TechniquesEachbookwillbeacomprehensiveguideforboththeamateurandprofessionalengineerAlatheisessentialtoallbutthemostbasicofworkshopsIt

enablesyoutoproduceturnedcomponentstoahighdegreeofaccuracywiththeminimumofeffort

ThebasicMyfordmodeltheML7wasmanufacturedformanyyearsTensofthousandsarestilltobefoundingaragesfactoriesandhomeworkshopsaroundtheworldThisistheprototypeML7LatheasrebuiltbyMyfordLtd

ThelaterML7RandSuper7modelswerefittedwithaclutchasstandardThissaveswearandtearontheelectricalcomponentsandthemotorTheyalsohadmorespeedsLaterversionsoftheSuper7canbefoundwithapowercrossfeedTheillustrationshowstheprototypeSuper7latheagainithasbeenrebuilttofactorystandardsbyMyfordLtd

TheAtoZofalathe(A)Changewheelguard(B)Countershaftpulleyguard(C)Drivebeltguard(D)Countershaft(E)Belttensionlever(F)

Oiler(G)Motor(H)Tumblergearoperatinglever(I)Headstock(J)Backgearoperatinglever(K)Mandrelnose(L)Left-handleadscrewbearing(M)Leadscrew(N)Halfnutoperatinglever(O)Toolclamp(P)Topslide(Q)Crossslide(R)Saddle(S)Apron(T)Carriagehandwheel(U)Screwthreadindicator(V)Lathebed(W)Rack(X)Tailstock(Y)Tailstockhandwheel(Z)Right-handleadscrewbearing

AnearlyMyfordlatheAlthoughverybasicitcandoalotofusefulworkintheworkshopespeciallyiftimeisspentonmakingafewsimpleaccessories

This book will show you how to use the lathe safely andeffectively in your workshop but first you should ensure thatyou are familiar with the main parts of the lathe and theirterminologywhichmaybefoundonpage9Chapter1ofthisbookisaboutchoosingalathewhatsizeof

lathe to buy the different types available desirable featuresandwhetheryoushouldbuyneworsecond-handChapter 2 covers installing a lathe how to lubricate it and

maintain it in good condition and advice on general safety inyourworkshopwithparticularemphasisonhowtousea lathesafelyChapter3will lookatthematerials fromwhichcuttingtools

aremadeaswellastheirbasicshapeandgeometryThenwe

willlookatselectingsuitablespeedsandfeedsChapter 4 dealswith sharpening lathe tools andhow to set

themupinthelatheChapter 5 covers the different types of chucks how to use

themandsetworkupaccuratelyinthemChapter 6 teaches you basic turning between centres and

then introduces turning with the work mounted on the lathefaceplateChapter7isaboutholdingworkinacolletandhowyoucan

make and use several different types of mandrel forworkholdingChapter 8 explains how to turn a taper using the top slide

theuseoffixedandtravellingsteadiesandmakingaformtoolChapter9explainshowtousedrillsandreamersinthelathe

includinghowtoselectthecorrectspeedsandfeedsChapter 10 shows the different ways to bore holes in the

lathewiththeworkheldinachuckmountedonthefaceplateorheldonthecrossslideChapter 11 explains how to use knurling tools and radius

turning tools as well as making simple form tools and basicproductionmethodsChapter 12 shows you how to use taps and dies to cut

internalandexternal threads in the lathe Italsoexplainshowto set upa simplegear train and cut a screw threadwith thehelpofascrewcuttingdialindicator

1BuyingYourFirstLathe

WHATSIZEOFLATHEDOIREQUIRE

ThefirstthingtoconsiderwhenbuyingalatheisthesizeoftheworkthatyouwanttodoWhatisthelargestdiameteryouwillwanttoturnonitandwhatisthelongestlengthyouwillneedtoturnA3frac12times18in(90times457mm)lathewillallowamaximumdiameterof7in (178mm) tobe turnedover the lathebed thelatterfigureisknownastheswingInpracticethoughthisisatheoreticalmaximumas it is stillnecessary toholdandclampthe article being turned The swing over the cross slide isusuallymuchsmallertypically2in(50mm)Many lathes however aremanufacturedwith a gapbed at

the headstock end to enable short items of a large diametersuchaslocomotiveortractionenginewheelstobeturnedLathes are also sometimes available as standard and long

bed lathes The long bed lathe as the name suggests allowslongermaterial to be turned within the capacity of the latheWhen turning longermaterial the diameter will be limited bytheswingoverthecrossslideThiswillbealotsmallerthantheswingoverthebedIfbuildingamodelsuchasatractionengineoralocomotive

the deciding factor for the size of lathe is likely to be thediameterof the largestpairofwheels thatneed tobe turnedBefore deciding on the size of lathe required you shoulddetermine the size of the largest diameter and the longestlength of material that needs to be turned Another factor indeterminingwhat lathe tobuy is theavailabilityof sparesand

accessoriesisthecompanystilltradingwillitstillbetradinginthe future and are there large amounts of secondhand partsandaccessoriesavailablefromtooldealersoroneBay

Atypicalinvertertoconvert240voltssinglephaseto240volts3phase

LATHEELECTRICS

Single phase electric is where the lathe plugs into the mainssupplyinyourhouseThemotorwillhavetheusualliveneutraland earth leads Lathes supplied for factory use usually havethree phase motors and require three live wires each of adifferentphaseThinkofaphaseasan incomingwaveon theseashore three successive waves make up the three phasesneededEachphaseisthesameastheprecedingonebuttheyareoutofsyncandallpeakatadifferenttime

Aforwardreversecontrolboxforaninverter

Convertersandinverters

Youcan runsome3phasemotors fromasinglephasesupplyviaaconverteroraninverterThemotor informationplatewillusuallysay240volts440voltsif it iscapableofrunningonaninverter Inside the motor there will be changeover tags tochange the motor from 440V down to 240V Follow theconverterinverter manufacturerrsquos instructions for furtherinformation It isnotusuallyverycomplicatedto runa240V3phasemotor from an inverter and thiswill give a quieter andsmoother running motor than a single phase supply canprovide This usually requires some simple programmingexplainedintheinverterrsquosinstructionsanditusuallytakesfiveminutestogetthemotorworkingproperly

ThismotorispartoftheinverterpackageshowninthepreviousillustrationNowiringisinvolvedasthemotorleadplugsstraightintotheinverterbox

Theinverterrunsataconstantvoltagebutthespeedofthemotor will change as the frequency is raised or lowered Isuggest limitingyour inverter from full speed tohalf speed sothatthefanstillcoolsthemotorandstopsitfromoverheatingyoucanthenusethebeltstochangethemainspeedstepsasusual(Ifyoumustuseveryslowrunningitispossibletoaddaseparatefansuchasacomputercoolingfantogiveconstantairflow) Most inverter suppliers offer a forwardreverse andspeedcontrolboxthatcanbesetupinaconvenientpositiononthe machine These are well worth fitting for convenience inuse

Thisinverterisdesignedformountingonthefrontofthelathe

While inverters are designed to run only onemachine youcangetconverterstopowermorethanonemachineatatimeDependingonthesizeandpoweroutputconverterscostaboutthreetofourtimesasmuchasaninverterTherearetwomaintypesofconverterRotaryconvertersare

designedtorunmorethanonemotoratatimeThisis ideal ifyouwanttorunmorethanonemachineortwomotorsononemachineforexamplethemainmachinemotorandperhapsanauxiliary motor that drives the machinersquos coolant pump orpowerfeedsystem

Arotaryconvertercapableofpoweringmorethanone3phasemotor

ThesecondtypeisthestaticconverterwhichisdesignedtorunonemotoratatimeThereisofcoursenothingtostopyouusingthestaticconverteronmorethanonemachinebyfittingasuitablefemaleelectricalconnectortothestaticconverterandmatchingmaleconnectorstotheindividualmachinesThiswayyoucanconnectthestaticconvertertoonlyonemachineatatime

Thisstaticconverterissuitableforpoweringone3phasemotorIfyoufitasocketontheoutputhoweverdifferentindividualmachinescanbepluggedintoitoneatatime

Theelectricalloadingonrotaryorstaticconvertersmustnotexceed theirmaximumrating If indoubton the loadcapacityneeded to run your machine(s) you should consult the

manufacturerorsupplieroftheconverter

AnearthleakagetripisidealforquicklyeliminatingamotorwheretheelectricalinsulationisbreakingdownItisusefulfordetectingcertainelectricalearthingfaultsbutshouldnotbeusedasaguaranteeofelectricalsafety

Simpleelectricaltestingandsafety

Whenbuyingasmallsinglephasesecondhandlathetakewithyouanearth leakage testerof the typeused for lawnmowersandothergardentoolsIonceboughtaUnimat3lathetookithomeandpluggeditinItkeptblowingtheearthleakagetripinthefuseboxeventhoughithadworkedperfectlyatthesellerrsquoshouseIsolditonatalossbutthebuyerdidknowtherewasaproblemwiththeelectricsIt is most important that the metal parts of any lathe are

connectedtotheearthwirewhichisinturnconnectedtoearthMake sure that themotor frame is also connected toearthassome motors have dampening rubber mounts that insulatethem from themachine itself If in doubt about any aspect ofelectricalinstallationpleaseconsultaqualifiedelectrician

Acontinuousbedisidealwhenworkingwiththefaceplateorwithcollets

LATHEBED

Thelathebedisthebackboneoftheentirelatheandisthepartthat is mounted on the bench or stand There are two maintypesoflathebedtheplainbedandthegapbedTheplainbedisusuallycontinuousallthewayalongitslengthwhilethegapbedhasas itsnamesuggestsagap in thebedThis isnotaliteralgapbutasteppedsectionthatallowsbiggerdiameterstobeturnedthanyouwouldotherwisebeabletoturnonaplainbed latheThisgap isameansofmakinga lathesmaller thanwouldberequiredforaplainlatheabletoturnasimilarsizeof

componentSome continuous lathe beds have a section next to the

headstock that can be removed to increase the diameter thatcanbeturnedThisfeatureisusuallyonlyfittedtolargerlathessuchasaremostlyfoundinfactoriesSome lathes have hardened beds although most are just

plaincast ironTherearethreemaintypesofbedwayscalledshearstheplainflatbedwithsquarewaysabedwithaflattopand a 60 degree dovetail at each side and a bedwith raisedandinvertedVeewaysOnthelastofthesethetailstockusuallyrunsononesetofVeesand thecarriageonadifferent setofVees resulting in lesswear to themain slidesWidebedsarebetterandmoreaccurateasthelathecarriageislesslikelytotwistonawidebed

Close-upviewofatypicallathebedwithagapAgapbedlathehasalargerturningdiametercapacitythantheequivalentsizedcontinuousbedlathe

Someveryearly lathessuchas thosemadebyDrummondhad a round bed Although they worked well there is noadjustmentforwearinthelathebed

TheMyfordrangeoflatheshasasquareformofbed

ThistypeofbedhasaflattopwithaninvertedVeeateachsideTheVeesareusuallysetat60degreesbutcanvarywithdifferentmakers

The Unimat SL lathe was sold for many years and manysecondhandexamplesarestillavailableThismodeldiffersfrommostlathesinthatithastwosteelbarsasabedThisisnotaproblemhoweverastheUnimatisintendedonlyforverysmallandlightweightmodel-makingworkandthereistheadvantagethatthebedcanbereplacedbyfittingnewbarsWhen buying a secondhand lathe it is most important to

checktheconditionofthebedYouneedtomakesurethebedis reasonably free from dings rust and hacksaw marksHacksawmarksneartheheadstockareoftencausedbysawing

offworkwhile it isheld inthechuckdingsareusuallycausedbydroppingthechuckonthelathebedwhenscrewingitonoroffthemandrelAsimplechuckboardplacedonthebedwhilefittingorremovingthechuckwillprotectthebedItisalsoidealfor protecting the bed when filing or hacksawing work in thechuck

AlathebedwithraisedandinvertedVeesThecarriageusuallyslidesononesetofVeesandthetailstockslidesontheother

AmodernChineselathebedwithaninvertedraisedVeeThecarriageandtailstockusuallyslideonthesameVee

Wear ismost commonly found at the headstock end of thelathe as a result of machining many short components andrelatively few long ones Make sure the lathe carriage isproperlyadjustedattheheadstockandthenrunitalongasfaras you can towards the tailstock The carriage should bereasonablyfreebutnotlooseallthewayalongthebed

OldroundbedDrummondlathesarestillavailablesecondhandThisparticularexampleistreadledriven

AflatbedlathewithsquarebedwayssuchasaMyfordcanbe checked for wear on the lathe bed using amicrometer orvernierCheckovertheworkingpartofthelathebedonwhichthe carriage slides rather than the part that is not used forguidance Check both the width and the thickness of the bedwaysThetailstockshouldalsobeagoodslidingfitonanyguiding

surfaces Wear is most likely to be found on the tenon thatslidesbetween thebedwaysAworn tenoncouldprobablybereplacedbutthereisnotmuchyoucandoifthetenonguidesarewornTheonlyway to fixawornbed requiresacompletebedregrindThisislikelytobeexpensivesoitwouldbebettertolookforanunwornlatheDecentunwornlathesareouttheresincemanymodelengineersmayhaveboughtthemnewfortyorfiftyyearsagoandhardlyusedthem

TheUnimatSLisaverypopularsmalllatheItsbedconsistsoftwosteelbarsthatcanbereplacedveryeasilywithsilversteeliftheygetwornormorelikelywhentheygetrusty

Asimplewoodenchuckboardwillprotectthelathebedfromdingsandhacksawmarks

LATHEHEADSTOCK

Theheadstockisthelargecomponentmountedattheleft-handside of the lathe bed It needs to have good bearings An all-gearedheadwillalmostcertainlyhaveballorrollerraceswhilethe older type of lathe for amateurs may well have plainbearings either phosphor bronze or whitemetal These areperfectlyadequatebutyoushouldmakesurethere isnowearinthemSomelathesalsohaveamandrelthatrunsdirectly inbored holes in the cast iron headstock casting Plain bearingswillbeperfectlysatisfactoryas longasadequate lubrication isused

Close-upviewofaMyfordheadstockonanML7RNotethelargebronzebearingatthefrontTheearlierML7latheshadwhitemetalbearingsalthoughtheC7capstanhadbronzebearingsandahardenedlathespindle

Tocheck forwear in the lathersquosbearings fitachuck to themandrelandputadialtestindicatorontopofthechuckGentlytry levering the chuck up and down by using a steel bar orsimilarheldinthechuckYouarelookingforminimalmovementhereespeciallyonaheadstockfittedwithballraces

CheckingthelathebearingsforwearAnymovementupanddownindicateswearinthebearing

The mandrel is mounted in the headstock and is usuallythreaded to take a chuck or faceplate The lathersquos mandrelshould not move back and forth in the bearings If it doeshowever itwillprobablybepossibletoadjust ittocorrectanyendwise movement The mandrel should not be too stiff butshouldturneasilybyhandWhentestingalathemakesuretheheadstockbearingsare

correctlyadjustedsothatwherepossiblethereisnoplaySeta tool up take a trial cut alonga length of bar and check forchatter If you are using a correctly set tool and a suitablespeedchatterisasuresignofwornbearings

Manylatheshaveathree-orfour-stepdrivepulleyasthesecondstageofthedrivechain

POWERDRIVE

Manylatheshaveathree-orfour-steppulleyonthemandreltotake the drive from a similar pulley on the countershaft Thecountershaft is in turn driven from the motor which is oftenmounted at the back of the headstock and completes theintegral drive system that is so popular on most amateursrsquolathes

Thisparticularlathehasatwo-stepmotorpulleyandcountershaftwhichdoublestheavailablespeeds

SpeedchartonthebeltguardofaMyfordML7Rlathe

AfewlatheshaveaclutchfittedasstandardorasanoptionalextraTheclutchsaveshavingtostartandstopthemotorwhileitisrunningThishelpstostopwearandtearonthemotorandelectricalsystemAdifferenttypeofclutchsystemtheTriLevaspeedselector

wasonlyfittedtoMyfordML7orC7lathesThishasthreeleversfor setting threedifferent speedsDependingon the leveryoudepressyougetahighmediumorlowspeedIfyoupressoneof the levers downwhile another is right down the first leverwilldisengagethesecondsostoppingthemandrelfromgoinground If the lathe is switched off and all three handles aredepressed the mandrel is locked preventing rotation This isusefuliffilingorhacksawinginthelathe

TheclutchisnormallymountedinsidethelargecountershaftpulleyItisusuallyoperatedbyaleverattheright-handsideoftheheadstockattachedtoapushrodthatpassesrightthroughthecountershaft

TheMyfordTriLevaattachmentwillonlyfitML7andC7lathesandisnotsuitableforML7RorSuper7lathes

Therehasbeenatrend inrecentyearstodoawaywiththecountershaftandpulleysystemandtoreplacethemotorwithavariable speed one with an electronic controller This isacceptable except that at low revolutions it does not providethe torque that can be obtained from a countershaft systemThereisalsothedisadvantagethatthereisnowaytodrivethelatheifthecontrollercircuitboardfailswhereasyoucanjustfita new one if the belt breaks The board could of course befixed provided that a circuit diagram is available and theelectronic components can be identified Sometimes thecomponents are marked with internal house numbers ratherthan commercially recognized part numbers that can beorderedasareplacementfromacatalogueSomeboardsmighteven have the identification marks removed to make repairsalmostimpossible

ThethreadedendofalathemandrelisdesignedsothatthechuckbackplaterunstrueIfthechuckmountingfaceofthebackplateismachinedinsituthechuckshouldruntrueaswell

CHUCKMOUNTINGSYSTEMS

The threaded lathe mandrel nose is not by itself a suitablelocationforachuckorfaceplatesothenoseisusuallygivenaturned register on which to locate the chuck The chuck isscrewedrightontothemandrelovertheregisterandbuttsuptoaturnedcollartokeepthechuckrunningtrueTheothersideof the mandrel collar butts up against the main headstockbearingwhichusuallyactsasathrustfaceThemandrelisusuallyboredthroughandmachinedtotakea

MorsetapercentreforturningbetweencentresDonotputyourfingerineitherendofthemandreltocleanitwhilethelatheisrunningAneasywaytocleanthetaperintheheadstockiswithabottlebrush often sold in chemists to cleanbabiesrsquo bottlesAnalternativeisasoftfeltshotgunbrushdonotuseonemadefromwire

ThislathehasaplainregisterAccuracyreliesonthelathechuckbeingagoodfitontheregister

There are various systems of chuck mounting in useespeciallyon the larger lathesTheproblemwith thescrew-ontype with a register mentioned above is that the chuck orfaceplatecanunscrewwhenthelatheisrunninginreverseTheonly timeyoushould run this typeofmandrel in reverseveryslowly and without taking a cut is if you need to return thescrewcuttingtooltothestartofthethreadyouarecuttingAlternativespindlenosescanbeaplaindiscwitharegisterto

boltthechuckontooracamlockwherethechuckisheldontightlybyturningstudstolockthechuckontothemandrelTheplain discwith register relies on having chuckswith amatingregistertoworkproperly

AnAmericanstandardCamLockchuckmountingbackplateandCamLockchuckplatefittedtoachuckTheyareusuallyfittedtolargerindustriallathes

TheAmericanDstyleCamLocksystemeithertakesachuckor faceplate directly or it has a backplate that can have aregisterturnedonittosuittherequiredchuckAlthoughmanylathe mandrels with Cam Lock fittings have six holes thematchingchuckorfaceplateoftenhasonlythreelockingpinsThe advantage of both of the last two systems is that they

canberuninreversewithoutthechuckcomingoffthemandrel

Theleadscrewisdrivenfromthemandrelviaageartrain

SCREWCUTTINGGEARS

The left-hand end of the mandrel will often have a gearmountedonittodrivethechangewheelgearsandleadscrewThe mandrel gear usually drives a pair of gears called

tumblergearswhicharemountedona leveratthe leftoftheheadstock The direction of the leadscrew can be changed bybringingeitheroneortheotherintogearbyraisingorloweringaleverThereisusuallyacentralneutralpositionwhereneithergearisinmeshThissaveswearonthelathechangewheelsandleadscrew bearings as well as reducing noise while workingMandrelandtumblergearswillbediscussedfurtherinChapter12whenwesetupascrewcuttinggeartrain

A set of changewheels usually comprises about a dozengearsbutthiscanvarydependingonthemanufacturerThesechangewheels which take the drive from the tumbler gearsdown to the leadscrew are mounted on moveable studs toensurethegearsareinmeshwitheachotherDependingonthenumber of gears in the train the leadscrew will turn eitherclockwiseoranti-clockwiseThedirectionof the leadscrewcanbe reversed using the tumbler gears to enable right-hand orleft-handthreadstobecut

Oftentherearetumblergearsinthegeartrainthatcanreversethedirectionoftheleadscrew

YoucanusuallysetthegearstocutaveryfinepitchsothattheleadscrewactsasaselffeedwhenturningfromthesaddleIf you anticipate the need to do any screwcutting check thatthesuppliedscrewcuttinggearswilldotherangeofpitchesyourequire It has been known for certain lathes to be unable tohandle somecommonpitches a typical examplebeing26TPI(teeth per inch) A pitch of 26 TPI is often needed to repairmotorcycles and bikes made before the introduction ofmetrication

MakesurethatafullsetofchangegearsisincludedwiththelatheIfnottheyarereadilyavailablesecondhand

LEADSCREW

The leadscrew ismounted at the front of the lathe there areusuallybearings to support the leadscrewateitherendof thelathe bed It is used tomove the lathe saddle along the bedeither for a self acting feed or for screwcutting Some lathesalso have a graduated handwheel mounted at the right-handendoftheleadscrewforturningthemandrelbyhandSome of the larger lathes also have a separate feed shaft

whichisusuallyaplainroundshaftwithakeywaycutalongittodrivethesaddleusingafinefeedThissaveswearandtearontheleadscrewwhichisthenonlyusedforscrewcutting

Mostleadscrewscanhaveagraduatedhandwheelmountedontheright-handendoftheleadscrew

SCREWCUTTINGFACILITIES

Ausefulfeatureonanylatheistheabilitytocutscrewthreadsof different pitches Leadscrews come in different pitches acommon one being 8 TPI but many variations are fitted todifferent lathes including leadscrews with a metric pitch It isawkward tomachinemetricscrewswithan imperial leadscrewandviceversaSometimesmetricconversionsetsareavailablebuttheycanbehardtofindareusuallyexpensiveandrequirethe lathe to be changed over often using 127 tooth gearwheels This figure is derived from multiplying the metricequivalentof1in(254mm)byfivea127toothwheelisthusadirectconversiontoametricthreadonalathewithanimperialleadscrewA127 toothgear isusuallyvery large if itmatchesthepitchoftheremainingscrewcuttinggearsbutyoucouldusesmallergearswitha smallerDP (diametralpitch)but stillwith127 teeth Youwould also need amatching gear of say fiftyteethtogiveyoua2541ratio

Thislathehasbothaleadscrewforscrewcuttingandadriveshaftforthesaddleandcrossslidefeeds

Ascrewcuttingdialindicatorusuallymountedtotherightofthe carriage is a useful feature This is a small dial withdivisionsmarkedonitmountedonashaftTheotherendoftheshafthasagearthatmesheswiththeleadscrewandmakesthedial go roundWhen the clasp nuts are engaged the carriagemoves and as the gear moves at the same speed as thecarriagethedialstopsgoingroundWhen you engage the clasp nuts on the leadscrew the

positionwhereyouengagedependsonthepitchofthethreadbeing cut Some thread pitches allow you to engage at anydivision of the dial while others need to be engaged at aparticularpositionof thedialTheuseof thescrewcuttingdialindicator will be covered in Chapter 12 When using the finefeedyoucanengagetheclaspnutsatanymarkedpositiononthedialsoavoidingweartotheclaspnuts

AtypicalscrewthreaddialindicatorThisoneisengagedanddisengagedbylooseningtheboltandengagingthedrivegearwiththeleadscrew

LATHESADDLEANDAPRON

The saddle is thepart that slides on top of the lathebedandusually has the cross slide and top slide mounted on it Theapron ismounted to the frontof the saddleYoushouldmakesure there isnoplay in the saddle either sidewaysorupanddownandthatittravelsfreelyfromoneendofthelathebedtotheotherwithnotightspotsAtthefrontnearesttheoperatorthereisusuallyapairofclaspnuts(thesearesplitnuts)Thesecan be engaged or disengaged from the leadscrew forscrewcuttingormovingthesaddlealongwiththeleadscrewOncheaper lathes there is usually a solid nut that cannot bedisengaged

ThelathesaddleslidesalongthelathebedTheapronisboltedtothefrontofthesaddle

There is often a rack at the front of the lathe bed thatmatches upwith a handle and gears on the lathe apron Thiscan be used to move the carriage along the bed withoutwearingouttheleadscrewSomelatheshavethecarriagefeedwheel on the right but others have it on the left where hotswarfcanfallontoyourhandsThecheaperlatheshavenorackandrelyontheleadscrewtowindthecarriagebackandforth

ATee-slottedcrossslidemakesthesmalllathemoreversatile

CROSSSLIDE

On top of the carriage is the cross slidewhich canbewoundbackandforthacrossthelathebedWhenusingthecrossslideforfacingacrosstheworkthecarriageshouldbelockedtostopitmovingalongthebedLathesforamateurusearemorelikelytohaveaTee-slottedcrossslidewhilelargercommerciallathesare unlikely to have this facility The Tee-slotted cross slide isveryusefulespeciallyifyoudonrsquothaveamillingmachineYoucanboltworktothecrossslideformachiningusingacutterinthechuckorforboringworkpiecesthataretoolargetoswinginthechuckZero settingdials aredesirable for both the cross slide and

thetopslideTheyallowyoutosetthedialtozerowhichmakesiteasiertomeasuretheamountyouaretakingoffwithonecutInusewindthetooluptotheworkandtouchonsetthedialtozeroandwind the toolbackoff from theworkYounowknowwherezeroisonthetoolandcantaketherequireddepthofcut

withouthavingtoworkitout

Zerosettingdialsmaketurningandscrewcuttingtodepthveryeasy

Apairofzerosettingdialsreadytofit

LathescanbepurchasedwithimperialormetricfeedscrewsMostmodeldesignsareimperialbutmetricismakingheadwayandthismaywellbethewaytogoBewarelatheswithimperialfeedscrewsandmetricdialsTypically thesewillhavea funnynumber of handwheel divisions rather than a whole numberMostofthelathesyoumightcomeacrossareunlikelytohavea

power cross feed for facing This does notmatter as you caneasilywindthecrossslideacrossbyhandTheonlytimeIhavefound a power cross feed to be of use is when I had to faceacross a faceplate to true it up I have trued up similar sizefaceplatesbyhanditjusttookalittlelonger

Thetopslideismountedonthecrossslide

TOPSLIDE

ThetopslideismountedontopofthecrossslideThetopslideisnormallysetat90degreestothecrossslidealthoughitcanusually be swivelled around to various angles for turning ataperanangleorforscrewcuttingSomeofthecheaperlathesdonrsquothaveatopslideasstandardbutitisaveryusefulfeatureif you can get one The top slide should be able to rotateespecially for screwcutting but the top slide handlemay foulthecrossslideincertainpositionssocheckifthisisaproblemTheturningtoolisusuallymountedonthetopofthetopslideItcan either be clamped on directly usually with packing stripsunderneathorthetoolcanbemountedinatoolholdersuchasathree-orfour-waytoolpostoraquickchangetoolpostWewilllook at tool holding methods in Chapter 4 when discussingsettingupturningtools

TAILSTOCK

The component at the right-hand end of the lathe is thetailstock This usually has a handwheel to feed a drill into theworkbut leverfeedandcapstan-style feedingmechanismsarealso available You can lock the tailstock anywhere along thebed The tailstock has a barrel inside it that can bewound inandouttogivealinearmovementtodrillaholeinworkheldinthechuckThetailstockisusuallyboredtoaMorsetaperoftenof a similar size to the headstock so it can take accessoriessuchasdrillchucksmountedonaMorsetaperItcanalsotakeacentre for turningworkbetweencentres It is important thatboth the headstock and tailstock tapers are free frommarksscratchesandburrs

AlathetailstockwiththebarrelextendedNotethatitisnotusuallyaproblemifthechuckkeyisleftinthetailstockwhilenotinuse

Adjustment is usually provided between the base and themain body of the tailstock to allow for setting the tailstock inlinewith theheadstock Tailstocks canbe self ejectingwherethetool isextractedas it iswoundbackwhilesometailstockshavea throughholeandneeda tapwithabar to remove thetool Handwheel depth graduations for drill drilling to a

particularholedepthareveryusefulbutarenotoftenincludedon the cheaper lathes although industrial lathes usually havegraduatedtailstockhandwheelsThebettermakesoflathehavea lever clamping tailstock arrangement while the cheaperlathesoftenhaveaclampingspanneroranAllenscrewclamp

Allguardsshouldbefittedinplacebeforeoperatingthelathe

MACHINEGUARDS

Thedrivemotorcountershaft(iffitted)andpulleybeltsshouldallbeproperlyguarded It isveryeasy togetcaughtup inanunguardedmachineandtheconsequencescanbequitenastyThis has never happened to me but I have seen someonecaught up in a machine and it was not very nice I dorecommend that you make sure your machine guards arecorrectlyfitted

OTHERDESIRABLEFEATURES

Digitalreadoutsareusefulonalatheastheycanshowyouhowmuch to move the handwheels and how much material hasbeentakenoffTheyarequiteexpensivebutyoucan fit themyourself if youare carefulUnfortunatelymost of the cheaperversionsdislikesolubleoilorothercoolantifyougetitintothereadouthead

Adigitalreadoutsuitableformountingonalathe

Youwillneedtwoslidesoneforeachaxis

A soluble pump for cutting fluid is useful and often comesfittedasstandardonthelargerlathesHoweveratinofcuttingoilandabrushwillbegoodenoughformostworkandthatmaysuityoufine

Solubleoilpumpsandreservoirsarereadilyobtainable

Formostjobsyoucangetawaywithsomecuttingoilabowlandabrush

TheMyfordlsquoNortonrsquostylequickchangescrewcuttinggearbox

A Norton quickchange screwcutting gearbox saves time asyou donrsquot have to set up changewheel trains A gearboxhowever considerably increases the price of the averagesecondhand lathe A Myford Norton gearbox has twenty-fourpitchesandiscontrolledbytwoleversReversingtwogears inthe Myford changewheel train gives the gearbox twenty-fourfine feeds insteadof the twenty-fourscrewcuttingpitchesThegearboxhasa setofgearsarrangedasaconeBysliding thelever along and dropping themaster gear onto the cone youcanchangethegearboxratioandsothepitch

TheconegearsinsideatypicalNortonscrewcuttinggearbox(notanoriginalMyfordone)

SeveraldesignshavebeenpublishedtomakeyourownNortontypescrewcuttinggearboxThisoneisavailablefromHemingwayKits

SPINDLESPEEDS

Thespeed rangeneededona lathedependson thework it is

requiredtodoAgoodrangeofspindlespeedsisdesirablewithnoobviousgapsWithelectroniccontrolthisshouldnotbetoomuchofaproblemIdeally a back-geared lathe would be best but this means

either a good secondhand machine such as a Myford or aBoxford or alternatively one of the larger Asian-made latheswithanall-gearedheadstock

Thisbackgeararrangementisswitchedinandoutbyturningthetoggleonthepulleyandliftingaleveratthefrontofthelathe

Backgearnormallyconsistsoffourgearstwolargeonesandtwosmalloneswhichcanbeswitched inorout toreducethespeedofthelathebyaratioofusuallyabout51dependingonthe maker to enable you to turn large diameter workpiecesThis reduction is also essential on a screwcutting lathe asotherwisethemandrelwillbegoingtoofastwhilescrewcuttingandyouwonrsquotbeable tostop in the rightplaceat theendofthethreadIf buying a back-geared lathe check that both gearwheels

havealltheirteethItisamajorjobtostripdownalatheandfitnewgearwheelsassumingtheyareevenavailableassparesCheckthelatheinallgearrangeswiththelatherunningIfa

back-geared lathe or an all-geared head is noisy it could

indicatewearitwillalsobeanuisanceinyourworkshopasnoonewants to hear a noisymachine runningNoise could be amajorproblemespeciallyifyouhaveneighboursnearbyGearedheadsusuallyhaveawiderangeofspeedsthelarger

industrial lathescangoup tospeedsof2000rpmandsmallerversionsareoftenhigher

Anall-gearedheadonamodernindustrialsizelathe

On the more usual amateursrsquo lathe there is often acountershaft usually tensioned by a lever which tightens upthebeltreadyforuseThemiddlespeedofthecountershaft isusually chosen to be about one quarter of the motor speedMost small lathes have three speeds and the back geararrangement adds another three speeds giving six in all TheMyfordSuper7rangeoflatheshavefourspeedsandbackgearmaking eight speeds but there is also a double pulley on themotor countershaft section making sixteen speeds in allalthoughtheverylowestback-gearedspeedswillrarelyifeverbeusedSomeoftheolderColchesterChipmasterlatheshavewhatis

knownasaKoppVariatordriveThis isavariable speeddrivecontrolledbyadialandthesystemworkswellbuttheVariator

isveryhardtoreplaceifthedrivefails

ThissmallCowellslatheiscapableofdecentworkandatthetimeofwritingisprobablytheonlylathestillbeingmadeinBritain

MOUNTINGTHELATHE

There are three main options for mounting a lathe benchmounting portable or on a stand Ideally a makerrsquos standshouldbeusedformountingamediumto large latheandthestandisoftenanintegralpartof larger lathesAsmaller lathesuch as a Unimat or a Cowell can bemounted on a woodenchopping board or a similar small board These lathes can beputawayinacupboardafteruseThe alternative is a workbench but these are often made

from wood which can expand or contract depending on themoistureintheairWoodisnotagoodmaterialfromwhichtomakea stand for a larger latheas itwill attractmoisture andmayexpandshrinkordistortAmetalstandisabetteroptionWewilllookatinstallingthelatheinChapter2

AnArcEuroTradeC3screwcuttinglathemadebySiegThisisaverypopularentrylevellatheandmanyaccessoriesareavailable

Amedium-sizedscrewcuttinglathesuitableforgardenshedworkshops

SHOULDIBUYNEWORSECONDHAND

Beginnerssettingupaworkshopoftenaskifitisbettertobuyanew lathe or secondhand The preceding pages should have

given some guidance but there are more points to be takenintoconsideration

Alargerindustriallathewithafoot-operatedemergencycut-offswitchandbrake

BuyingNew

Thelistoflathesuppliersincludedatthebackofthisbookwereall in business at the time of writing Most will be willing todemonstratetheirrangeofmachinesattheirpremisesorwhileattendingmodelengineeringexhibitionsPaycloseattentiontomechanical noise the general paint finish and the workingslideway surfaceswhich should begroundDoes themachinehave sharpor roughedges (Handwheelsareespeciallypronetosharpedges)The main thing to consider though is the attitude of the

supplier Were they willing to talk to you and answer yourquestionseitheratanexhibitionoroverthephoneHowlongdo they take toanswer thephonewhenyou ring their servicedepartment Do they know the answer to a simple questionstraightawayordotheyhavetogetbacktoyouIsthemanual

written in English or Chinglish (translated awkwardly fromMandarinorCantonese)There are several suppliers of new lathes inmost countries

aroundtheworldbutthemajorityoflathesaremadeintheFarEastOftensupplierArsquosmachinescomefromthesamefactoryassupplierBrsquostheyarejustpaintedadifferentcolourandhavedifferentnamesandlabelsfittedAftersales service can vary greatly Usually companies that

havebeeninbusinesslongerwillofferbetteraftersalesservicebutotherpeoplersquosexperiencescanbefoundonInternetforumsoratlocalmodelengineeringclubsUsually theAsian lathesare reasonablywellmadebut they

often suffer from having plastic gears instead of metal onesOneortwocompaniessupplymetalgearsasstandardso it isworthaskingiftheirmachineshavemetalorplasticdrivegearsSome companies also offer after-market replacement metalgears

BuyingSecondhand

There aremany good quality secondhandmachines availablebut there is also a lot of worn-out rubbish If possible take aknowledgeable friend with you when purchasing a lathe Becareful when buying at online auctions such as eBay MostsellersaregenuinebutsomearenotNeverpartwiththecashuntil youhavechecked the latheover IhaveboughtoneBaywithoutproblemsbut Iamcarefulwhat IbuyandwhofromAsmall latheforacoupleofhundredpoundsisunlikelytobreakthe bank if it is a bit of a dog but a lathe that costs severalhundredpounds is adifferentmatter ThegreenMyfordML7RpicturedthroughoutthisbookwaspurchasedfromeBayItwasbrand new the motor had never been fitted and it was abargainwhencomparedwiththeretailpriceIdidpaycashoncollectionbutIwouldhavewalkedawayif ithadnotmatchedthedescriptioninanywayWhether purchasing new or secondhand check what

accessoriescomeaspartofthepackageandwhatwillneedto

bepurchasedseparatelyEssentialtoolingcanoftendoublethecost of a newmachine if it is not included in the price whilededicatedtoolingmaynotevenbeavailable forasecondhandbargainlathe

Youshouldnowhaveanideaofthesizeoflatheyouneedthefunctionofthedifferentpartsofthelatheandwhetheryouarebuying new or secondhand In Chapter 2 we will look atinstallingthelatheandsafetyintheworkshop

2InstallingtheLatheandUsingItSafely

If you are buying a new lathe completewith delivery to yourworkshopyoucangostraighttothesectiononsettingthelatheupIfyouarecollectingthelatheyourselfhoweveryoushouldpayattentiontoafewwordsonmovingit

Ifyouhaveroomtomanoeuvreanenginehoistcanbeusedtomovemachineryaroundsafely

MOVINGTHELATHE

MOVINGTHELATHE

When going to collect your lathemake sure someonewill betheretohelpyouloaditortakesomeonewithyouUnlessitisaminiaturelatheitwillbetooheavyforonepersontoliftHelpisalsoneededwhenyougetthelathehomeLiftingthelatheoutofacarcanbeharder than lifting it in It isadvisable tohavethreepeoplewhenunloading twoat theheavyheadstockendandoneliftingthelightertailstockendYoucanrentorbuyanenginehoist fora reasonablepriceand this canmakemovingthemachineeasierIf the machine is a substantial industrial type it would be

besttohireatransportcompanythatspecializes inmachineryremovals Professional machinery removers will usually haveproperlyequippedtransporttomoveheavymachinesThiswillprobablyworkoutcheaperthanattemptingtodoityourselfbutmake sure they have insurance in place in case they damagethelatheoryourpropertyYoushouldalsoensuretheyknowithas to beput in place as required in theworkshop youdonrsquotwanthalfatonofmachinerydumpedonyourdrivewithnowayofmovingitintopositionLathesareusuallytopheavywhenbeingmovedandcantip

overifyouarenotcarefulTheMyfordML7seriesforexampleoftenhasthemotorandcountershaftboltedtothebackofthelathe bed and this type of lathewill tend to tip backwards Asimple solution is to bolt two lengths of wood about 4 times 2in(100times50mm)tothelathefeetOneboltineachendwilldoifyou canrsquot drill holes in the correct position This will stop thelathe tipping backwards and also make it easier to lift IfpossibleyoushouldremovethetailstockThisisoftenaheavylumpofmetalbutitisusuallyveryeasytoslideitofftheendofthelathebedAnyotherlargeobjectsthatcanberemovedandreplacedlaterwillmakethelathelighterandeasiertomove

Twoplanksofwoodboltedtothelathefeetwilloftenturnanunmanageablemassofmetalintoaneasilyhandledmachine

Azerovoltsswitchisessentialequipmentonanymachinetool

Wearoldclotheswhenmovingyourlatheandhaveplentyofold rags to wipe off swarf and oil Lay down old blankets ordecoratorsrsquosheetsinsidethecarandasheetofthickcardboardMDForplywoodtohelpprotectthebootareawhenslidingthelatheintothecar

AsmallishlathecanoftenbefittedintoastandardhatchbackorestatecarYoumayfindhowever thatyouhavetodotwotrips one for the lathe and accessories and another for thecabinetthelathestandsonTosaveawastedjourneyIusuallytrytofitthelathecabinetinfirstIfIthenfindthatthecabinetdoesnrsquotfitIcanstillbringthelatheandtoolinghomeknowingthat Ihave tohireavan tocollect thecabinetbutalso that IhavenothadawastedjourneyIfyouhavetosplittheelectricsforexampletotakethelathe

offthecabinetdrawadiagramoftheelectricalconnectionssoyoucanrewirethelathewhenyougetithomeAdigitalcameraisalsoagoodmethodofrecordingthewiringconnectionsbutIwouldnotrelyonthecameraaloneIf the lathedoesnothaveazerovoltsswitch itwouldbea

good idea to fit one after you get the lathe home They areavailable quite cheaply andare easily fitted If in doubt aboutyourabilitytodoelectricalwiringconsultaqualifiedelectrician

Adjustablefeetareveryusefulforlevellingupthelathe

SETTINGUPTHELATHE

Somelathesusuallythelargerindustrialoneshaveanintegral

bedandcabinetThelathecanbesettotruewithjustshimmingunderthefeetorbyadjustingthefeetOther lathes may need to be mounted level and true to

ensureaccuracywhenturningSetthebenchstandas levelasyou can in both directions using a spirit level as a guide Anycheapspirit levelwilldoas longas it isaccurateYoucantesttheaccuracyofaspiritlevelbyturningitround180degreesifitisaccurateitshouldreadthesamebothwaysOnce the stand is reasonably level youcan level the lathe

ThisinvolvesjackingorshimmingupthelatheuntilitistrueinbothdirectionsIfusingawoodenbenchputmetalplatesunderthe feet tospread the loadShimoradjust the latheuntil it isreasonablylevel

Putthespiritlevelonthecabinetrsquoslongitudinalaxisandusetheadjustablefeettolevelthelathe

Insertalengthofbarinthechuckandputadialtestindicatoron top of the tailstock end of the bar Nip the headstock endmounting bolts down first and then tighten down the tailstockendboltsAdjustorshimthetailstockenduntilthereisnosignof movement on the test indicator Next 64repeat theprocedure with the dial test indicator on the front of the barAgainyouare looking fornomovementCheckbothdirectionsagainmakingsurethereisnomovementeitherhorizontallyorverticallywhenyoutightenthelathedownAdjustorshimuntil

there is no movement in either direction when the lathe isclampeddownAslongasthebedisnottwistedthelathebedshouldnowbetrue

1Insertapieceof⅛in(3mm)packingunderthespiritlevelatthetailstockendThiswillresultinarunonthedriptrayandalltheoldoilwillruntotheendofthelathemakingiteasiertocleanup

2Placethespiritlevelonthecabinetcrossaxisandusetheadjustablefeettolevelthelathe

3Putthespiritlevelonthelathecrossaxisattheheadstockendandlevelitasbestyoucan

4Putthespiritlevelonthelongitudinalaxisandlevelalongthelathe

5Testthetopofthebarthereshouldbenomovementwhenthelatheisclampeddown

6Testthefrontofthebaragainensuringthatthereisnomovementwhenthelatheisclampeddown

Alignthetailstockbyusingadialtestindicatorintheheadstock

AligningtheTailstock

NowweneedtosetthetailstockinlinewiththeheadstockDothisbyputting thedial test indicator into theheadstockchuckandtestthetailstockboreAdjustthetailstocktowardsthefrontortothebackofthebeduntilthetestindicatorreadstrueandtighten theclampscrewsA slightdifference inverticalheightwillnotbetheendoftheworlditjustmeansthereisprobablysomeweartothebaseofthetailstockcastingbutthereshouldbenovariationfromfronttobackinthehorizontalalignmentPutalongbarbetweenthecentresandtakealightcutalong

it using a fine power feed Run along the bar a couple moretimes at the same setting to remove any push offWhen youmeasure thebar it shouldmeasure the sameatbothends Ifthe bar is larger at the tailstock end you need to reduce theheightofthebedatthefrontofthetailstockslightlyIfsmalleratthetailstockendyouneedtoreducetheshimatthebackofthe tailstockend Itprobablywonrsquotneedmuchadjustmentasslightadjustmentstotheshimoradjustersatthetailstockendwillsoonbringitintoline

Usingatestbartocheckforparallelturning

LubricatingtheLathe

You should follow the manufacturerrsquos recommendations forlubrication Usually this is thin oil for the headstock oftenhydraulicoilandslidewayoil forthemovingpartsLubricationshouldbedoneregularlyIfthelatheisfittedwithasightfeedoileritshouldshowoilinitAdjustablesightfeedoilersasusedonMyfordandsimilarlathesshouldbeadjustedsothattheoildripswhen the lathe is running but does not dripmuchwhenthe lathe is stopped The slight vibration when the motor isrunningisusuallyenoughtocausetheoiltodripToomuchoilisbetterthannotenoughoilisfarcheaperthannewbearings

Atypicaldrip-feedlubricator

UseanoilgunonalltheoilnipplesYoucangetaroundthetendencyfortheoiltogoeverywhereexceptintothenipplebyputtingapieceofwritingpaperoverthenippleandthenusingthe oil gun as normal The paper will stop the oil squirtingeverywhereThemandrelbackgearalsoneedstobelubricatedWheninusethemainbackgearisrunningontheoutsideofthelathemandrelandneedstobelubricatedoftenoritwillgethotandwearChangewheels should be lubricated with oil not grease If

youusegreaseswarfwillsticktothechangewheelsandcauseunnecessarywearTo stopswarf running through themandrelanddroppingoutontothechangewheelsputawinebottlecorkor similar into the left-hand end of the mandrel This willeffectivelystopanyswarfgettingthroughtothechangewheelsOil the saddle and cross slide and also the nipples on the

tailstock Make sure oil is showing at the edge of the slidingsurfaces A squirt of oil on the cross slide and topslide feedscrew bearing is needed as well Check the manufacturerrsquosinstructions for lubricating the rest of the lathe Follow themotormakerrsquosrecommendationforlubricatingthemotorTrytoavoidusingWD40onthelatheWhileitisanexcellent

lubricantwaterdisplacerittendstodiscolourthelathebed

Useabitofpaperundertheoilguntostoptheoilsquirtingeverywhere

AvoidingtheRustFairy

Rust canplayhavocwith a lathe quickly turning thebedandother parts into a brownmess Various sizes of plastic coverssuitable forcovering lathesareoftensold foruseasbarbecuecoversinDIYstoresAplasticlathecoverwillhelptokeeprustatbaybutmoreneeds tobedoneAbagcontainingsilicagelplacedundertheplasticcoverforexamplewillabsorbexcessmoisturesilicagelcanbeboughtverycheaplyoneBay

SilicageliseasilyobtainablefromeBay

Alternatively you can buy a vapour phase inhibitor forprotecting the lathe The vapour phase inhibitor chemical issuppliedonafeltpadinsideaplasticpotThechemicalformsaprotectivelayeroneverysurfaceBecauseitisavapouritwillfind its way into every cranny and is also used for protectingtools and accessories in tool cabinets and drawers It usuallylasts for twelvemonths ifenclosedby theplasticcoverSomemachinetooldealersareabletosellsuppliesofthisproductinsmall ready to use containers rather than in industrialquantitiesAlwayscleanthelathedownafteruseswarfwillsoonrustif

leftonalatheasitwillprobablybecleanfromturningandwillnotbeprotectedbyoilTheuseofanovencookingtrayunderthe lathe bedmakes it easy to remove swarf at the end of aturning session The tray also helps to retrieve a parted offcomponentora lost screw froma tipped turning toolAnotheralternativeistocoverthelathechiptraywithnewspaperwhenyouhave finished turning remove thenewspaper screw it upandthrowitawayWhenfittingachuckorfaceplatetothelathemakesureyou

cleanthemandrelthreadtheregisterandthefaceYoushouldalso clean the mating threads the bore and the face on thechuckorfaceplateYoucancleanthethreadandboreeasilybyusing two toothbrushes bolted back to back with spacers inbetween Make sure the Morse tapers in the headstock andtailstock are cleanbefore fitting aMorse taper accessory TheMorse taper to be fitted should be free from scratches burrsandbruisesIt is good idea tomake a chuck board for usewhen fitting

chucks to a lathe or removing them This is a piece of wood(plywood will do) that sits on the lathe bed while you arescrewingthechuckonandoffThechuckboardwillprotectthelathe ifyoudrop thechuck It canalsobeused toprotect thelathebedwhenyouarehacksawingorfilinginthelatheIf you keep your lathe clean and lubricate it regularly it

shouldlastalifetime

AlargetraywillcatchmuchoftheswarfandtheholeslettheoildrainawayUsenewspapertosoakuptheexcessoil

SAFETYINTHEWORKSHOP

RememberyouareresponsibleforyourownsafetySafetyisamajorconcernintheworkshopTherearecertain

thingsyoushoulddoandobviouslythingsyoushouldnotByitsverynatureaworkshopcanbeadangerousplaceallwecandoismakeitassafeaspossiblewhilestillallowingustoworkinit

WorkingAlone

Mostofyoureadingthisbookwillprobablybeworkingaloneinasmallworkshopgarageorgardenshed IfyougethurtyoumaypossiblybeonyourownAsapriorityIsuggestyoutakeamobilephoneintotheworkshopandkeepitinyourpocketTheability to contact your family a friend or the emergencyservicesquicklycouldsaveyour lifeKeepthephoneswitchedoff while in the workshop however as it is an unnecessarydistraction

FirstAid

FirstAid

AFirstAidboxwithcontentsisanecessityandshouldincludeaneye-bathandeyewashYoushouldparticularlylearnhowtostopbloodflowingThereareplentyofwebsitesthatwilltellyouhowtodothisCheckthemoutnowbeforeyougobackintotheworkshop

ElectricalSafety

Checkforearthcontinuitywhilethemachineisunpluggedwithavoltohmmeterfromtheearthpinonthethreepinplugtothemetalpartofthelathe(somepaintmayhavetoberemovedforareadingtotakeplace)Youshouldgetareadingofzeroohmsorabeep if themeterhasacontinuity rangeYoushouldalsobe sure that the electrical sockets on the wall are correctlyearthedIfindoubtconsultacompetentelectricianLightingandelectricheatingshouldbeonaseparatecircuit

tothemachinessoyouwillstillhavelightifthemachinestripoutPlugasmalllightintothemachinecircuitsoyouhavesomelight if the lighting circuit trips out When I go on holiday Ialwaysturnoffthefusetripsforthelightinginordertomakeitmore difficult for intruders to move about quickly Leave thehouse alarm and smoke detectors on (The house alarmmayactivateeighthoursafter theelectricity is turnedoffwhenthebatteryexpires)

Adigitalmultimeterisveryusefulinthehomeworkshop

BeAware

Bementally alert while using the lathe Avoid operations thatmightputyourhandsatriskofenteringthemovingpartsofthelathe Do not operate any lathe while under the influence ofdrugs alcohol or prescription medication that may causedrowsinessorotherwiseaffectyourability to control the lathesafelyDonotattempttoworkonalatheandtalkatthesametimeIfyouhavetotalktosomeoneswitchoffthelathebeforedoingso

KeepItClean

TheareaaroundalatheshouldbekeptfreeofobstructionsThefloorshouldbecleananddrywithanyoilorotherspillscleanedup immediately The lathe should be kept clean and tidyMachinedangerareasshouldbemarkedontheworkshopfloorand observed Workbenches placed near a lathe should be

strongandequippedwithanon-slipsafetysurfacetostoptoolsor other items rolling onto the floor a rubber car mat willsufficeA rubberdoormat on the floorwill allow swarf todropthrough in order to save you getting swarf embedded in thesolesofyourshoes

Asuitablefloormatwillallowswarftodropthroughandhelpkeepyourfeetwarminwinter

LearntoUsetheLathe

Donotuseany lathebeforeyouare familiarwith thecontrolsandareawareofthedifferentwaysofstoppingitThismaybea clutch an onoff switch a No Volts release switch or anemergency stop button I strongly advise fitting a No VoltsreleaseswitchifyourlathedoesnothaveoneAswellasbeingusefulforstoppingthelatheinanemergencyitwillpreventthelathefromstartingupbyitselfafterapowercutIfyouarenotcomfortableworkingwith electrical equipment get a qualifiedelectriciantofittheswitchforyou

StaywiththeLathe

Nevereverwalkawayevenforamomentwhilethelatheyouare using is switched on Switch it off if you are leaving itunattended and only leave the lathe after it has come to a

completestopNeverleavealatheinanunsafeconditionMakesure that you have not left the chuck key in the chuck Thechancesarethatifyouarehalfwaythroughsettingupthelathewhen you return you will forget what you have or have notdoneIfindoubtleaveabignoticeremindingyourselftocheckthatthelatheissafebeforecontinuing

Donotleavethechuckkeyinthechuck

SwitchOffwhenAdjustingtheLathe

Shut off the power supply to the motor before starting anyoperationsrequiringaccesstothelathesuchaschangingtoolsmeasuring work mounting or removing accessories changingspeed and setting up change gears The lathemust be safelystopped Just zeroing a variable-speed drive is not safelystoppingitusethezerovoltsswitchtoswitchthepoweroffaswell

CheckbeforeStartingtheLathe

AlwaysrotateyourworkpiecebyhandtomakesureitclearsthetoolrestsaddleandbedDoublechecktomakesureyourworkis securely clamped in the chuck or between centres beforestartingthelatheBecertainthattheworkpieceturnsfreelyand

isfirmlymountedThespeedofthelathemustbecheckedbeforeturningiton

When turning irregular shapes start the lathe on a low speedandincreasethespeedbyapulleystepeachtimeIfthelatheisbouncingabout lowerthespeedandorbalancethework Ifthe work vibrates stop the lathe and check the reason ThechancesarethatyouarerunningthelathetoofastMeasuringequipment toolingandworkpiecesshouldnotbe

leftona latheastheycanvibrateoff intomovingcomponentsand be thrown around the room Check for loose items on alathebeforeuse

UsetheLatheGuards

NewlatheswillbefittedwithguardsoverthemotorshaftdrivebeltandspindlepulleysTheseguardsshouldalwaysbeinplacebefore using the lathe Any other moving parts should beguardedtopreventanythingfallingontothemovingpartsAlthoughguardsareoften removedbymachinistsprovided

they are constructed from clearmaterials and open and closeeasily theyaddsafetywithout interferingwith theworkbeingdone Guards will at the same time deflect swarf and anycoolantthatisbeingusedGuardsfittedtothelatheshouldnotbe removed while it is in use They should be made fromsuitablematerialandnothavesharpedgesTheyshouldnotberemovedforadjustmentandlubricationofthelatheunlessthisis unavoidable Lathemanufacturers donrsquot usually supply chipguards soaddingoneshouldbeconsideredChipguardswithmagnetic bases are available although they can attract steelswarftothemagnetPutthebaseintoaplasticbagtoaidswarfremoval

UseEyeProtection

Lathes can throw sharp metal chips considerable distancesespecially at high cutting speeds Apart from deep cuts thechipsmay leave the tool red hot cause skin burns and even

burnholes in clothing Youmust use safety goggles or propersafetyspectacleswhileintheworkshopAlwayswearindustrialqualitysafetyglassesfittedwithsideshieldsSpectacleswithoutsafety lenses are not adequate eye protection When theglasses get dirty do not wipe them off as they will becomescratchedWashthemoffunderthetapinstead

TakeCarewhenRemovingSwarf

Do not attempt to remove chips or turnings with your handsAlwaysswitchoff the lathefirstandeitherpull theswarfawaywithalargemetalhookorliftitoffusingapairofglovesIftheswarf is tangled around the lathe untangle it with a pair ofpliersandnotaglovedhandasitwillcutstraightthroughtheglovesandintoyourhandUseadustpanandbrushtoremovesmall chips and swarf from the swarf tray ndash never use yourhandsWhenswarfbecomesstringyandbuildsuponthetoolortoolpostturnoffthelathebeforeremovingit

AvoidLooseClothing

IfyouarenotwearingoverallswearshortsleevedshirtsorrolllongshirtsleevesabovetheelbowsLoosesleevescancatchonrotatingworkandquicklypullyourhandorarmintothe latheObviously though keep your arms protected if hot swarf isflyingaroundSwarf can get inside protective clothing especially collars

(useaclothespegtokeepyourcollartight)pocketsandshoesTostopthesleevesofanoverallcatchingsewelastic intothecuffsorwrapacoupleofthickelasticbandsaroundthecuffstostopthesleevesgettingcaughtupUnder no circumstances wear a necktie when operating a

latheProtectiveglovesshouldneverbewornwhileoperatingalathe Protective gloves may be worn when swarf is beingremovedbuttheymustberemovedbeforeswitchingthelathebackon

UseSturdyFootwear

WearsteeltoecapsafetybootstheyarenotexpensiveandwillhelptoprotectyourfeetfrominjuryifyoudropaheavyobjectonthemThelsquotrainerrsquoversionisparticularlycomfortableDonotallow stringy swarf to fall on the floor as youwill get cuts onyouranklesandmayeventripoverit

AvoidJewellery

Do not wear wristwatches rings or jewellery when in theworkshop as it could catch on a rotating part of the lathe orworkpieceThisalsoapplieswhenmovingalatheintooroutoftheworkshopsincetheycouldcatchona falling lathe IfyourotherhalfcomplainsthatyouhavetakenoffyourweddingringexplainthatyouwouldnrsquotbeabletowearitagainifyourfingerismissingduetoanaccidentLonghairshouldbetiedbackasyoucouldbepulledintothelatheifitgetscaughtintherotatingwork

LiftingintheWorkshop

Back injuries can be caused by incorrect lifting practices It isimportant to bend your legs when lifting rather than bendingyour back A hoist or engine lift should be used to lift heavyitems A stool in theworkshopwill take the pressure off yourlegs and will provide a welcome break after you have beenstoodatthelatheforawhile

Self-ignitingMaterials

If you machine titanium or magnesium which can ignite andburn vigorously keep the accumulation of turnings to aminimum If thematerialdoescatch firedonrsquotusewaterorawater-based coolant as an extinguisher since it will makematters much worse Before starting to machine titanium ormagnesiumfillalargebucketwithdrysandcoveritandkeep

it by the lathe The sand will smother the flames veryeffectivelyYoucouldalsobuyoneofthespecialfireretardantsusedinindustryBeware also of grinding aluminium on the bench grinder

Aluminium and steel filings are the ingredients of Thermite apowerful explosive that can also burn If you grind aluminiumandthenchangeovertogrindingsteeltheredhotsparksareliable to set the steelaluminium mix on fire This is a verydangerous combination ofmaterials and should be avoided atallcosts

SafetywithBarStock

Bar stock should be contained within the headstock and notallowed to protrude from the rear of themandrel I once sawsomeone switchona lathewhenabrassbarwas stickingoutfrom the back of the headstock by about two feet With thelathe running at 2000rpm the bar whichwas aboutfrac34in (19mm) in diameter was bent at right angles and caused theheavy lathe which weighed 1280kg to jump about Luckilysomeone managed to switch the lathe off before any majordamageoccurredItwasnottheoperatorhehadrunwellawayandwasnowheretobeseen

SomeFinalWordsonSafety

Wherever possible the machine height should be adjusted tosuittheuserWearestillusingfifty-year-oldmachinesbutfiftyyearsagothenationwasshorterTheworkplaceshouldbeprovidedwithuniformlightingthat

gives an adequate level of illumination Individual machinelightsarebestThe lathemust be set to operate at the speeds and feeds

recommended for thespecificmetalbeingturned If themetalrotatestooslowlyortooquicklyorthefeed istooslowortoofastaccidentsarelikelytooccurThe area directly in front of and behind the workpiece is

known as the lsquofiring zonersquo or the lsquored zonersquo This is where apiece of work is likely to go as it leaves the lathe Make it ahabit to keep clear of this zone when you turn the lathe onLearnwhere theNoVolts switch is as youmightneed to turnthelatheoffquicklyByfollowingalltheaboveadviceyoushouldnowbeableto

worksafelyfullyawareofanysafetyproblemsthatmightariseAtthispointyounowknowhowtoinstallthelathelookafter

itclean itandmaintain it InChapter3wewill lookatcuttingtoolsandexaminehowtoselectcuttingspeedsandfeeds

Thisbarisstickingouttoofarfromthebackofthelathe

3CuttingToolPrinciplesFeedsandSpeeds

The first part of this chapter will look at the materials fromwhichcuttingtoolsaremadeaswellastheirbasicshapeandgeometryWewill thenconsider selectingsuitablespeedsandfeeds

MAINTYPESOFTURNINGTOOLS

There are three main types of turning tool used in modernworkshops HSS (high speed steel) tools carbide brazed-ontoolsandinsertedtiptoolsAllhavetheirusesintheworkshopandformost jobsthere isnopreferenceforonetypeovertheothersTherearealsocarbonsteeltoolbitsalthoughinpracticetheyarejustaboutobsoleteCarbonsteeltoolscanbemadeinthe homeworkshop but apart frombeing used tomake formtools(seeChapter11)thereaderisunlikelytousethismaterialfortools

Ageneral-purposeHSSturningtoolsuitableformildsteel

HSSTOOLS

HSStoolscanbepurchasedsinglyorinsetsalreadygroundtothecorrectshapeIt ischeaperhowevertopurchasethemassquare tool blanks in various sizes ready for you to grind toshapeThecompleteready-groundsetswillprobablycomewithseveralshapesincludedthatyouwillneveruseIfyoucanbuyafewready-groundtoolscheaplytheywillbeofuseasguidestoseehowtosharpenyourownHSStoolblanksHSS form tools from industry are often available second-

handTheseareespeciallygroundtomachineacomplex formall in one go You can often find some that are ground to asuitable shape to form the end of a threaded componentincludingtheundercut

HSSformturningtools

Brazed-onCarbideTools

Brazed-on carbide-tipped tools are quite useful especially forfacing and boring cast iron but they really need a diamond-facedgrindingwheeltokeepthemsharpCarbidetipsandtoolscomeinvarioussizesandhardnesstosuitindividualmaterialscarbidetoolsforsteelwilloftenbepaintedbluethoseforcastiron are painted red and those for stainless steel are paintedyellowThecolourindicatesthesuitabilityofthetoolforcertainmaterials

Brazed-oncarbide-tippedtoolscomeinvariousgradesshapesandsizes

InsertedTipTools

InsertedcarbidetiptoolsareveryusefulbuttheyarenotcheapThe tipsarenotusually sharpenedafterwearingout you justthrow the tip away and fit a new one Most modern carbide

inserts however do have more than one cutting facesometimestheyhavetwoandoccasionallyfourormorecuttingedgesareavailableYoucanevengetformturningtoolswheretheinsertisroundandcanberotatedafull360degrees

Theleft-handtoolisblueindicatingitisformildsteelwhiletheright-handtoolisredindicatingitisforturningcastiron

Some diamond-shaped tips can be used in different toolholders two edges are used in one tool holder and the othertwoedgesareusedinanothertoolholdersoyougettwicethelifepertipInserted tip tools are available for internal and external

screwcuttingwherethetipsareheldat thecorrecthelixangleofthethreadinthetoolholderThedrawbackisthecostofthetipsandeachsizeofthreadusuallyneedsitsownsizeoftip

Aninsertedtipcarbideturningtool

Carbidegroovingtools

InsertedtipgroovingtoolsareidealformachininggroovesforOrings and circlips Theyare available inmany standardwidthsandcanoftenbeusedasparting-offtoolsforsmallerdiametersOneof themostusefulgrooving tools forsmallersizegroovesandpartingoffistheMiniThinsystemassoldbyMSCIndustrialSupplyCo

TheMiniThintoolholderisidealforgroovingandalsoforpartingoffsmalldiametersTheshankissostrongcomparedwiththecutbeingtakenthatusinganoverhangasshownisquite

safe

Coatingstoreducetoolwear

Tipsarealsoavailablewith various coatings that improve toollifeThemostcommoncoatingistitaniumnitride(TiN)whichisgold in colour Other coatings that offer slightly better wearresistancearetitaniumcarbonnitride(TiCN)whichisbluegreyincolourandtitaniumaluminiumnitride(TiAlN)whichisvioletbronzeReady-groundHSScuttingtoolssuchasdrillstapsandreamers are also available with these coatings but once yousharpenthecutterthecoatingisgoneTipped toolsneedadeeper cut ahigher feedandahigher

speed than HSS tools Thismeans that the lathe needs to bestrongrigidandhaveamplepowertodrivethe lathemandrelwhen taking a heavy cut this rules out using tipped tools onlathessmallerthanabout2in(50mm)centreheightSmaller tools are made to fit the Unimat and similar small

lathesbutthesemachinesjustdonrsquothavethepowerneededtodrivethemAtbesttakingacutwillstopthelatheatworstthetoolwillchip

Insertedtiptypes

Inserted tip tools come in many shapes and sizes Some tipshapes and sizes are made to an international standard andothers are to the makerrsquos own standards Wherever possibleuse ISOstandardtoolsas thetipswillbe interchangeablewiththosefromothermanufacturersandwillprobablybecheaperaswell The ANSI system commonly used in the USA is notcompatiblewiththeISOsystemusedintherestoftheworldIfyour lathe ispowerfulenoughyoucantakeadvantageof

insertedtippartingoffbladesThesearemounted inaspecialtoolblockandthebladecanbeslidinoroutdependingonthediameteryouarepartingoffThebladecarriesan inserted tipspecially designed for parting off There are three types of tipavailablesquare-endedtipstipsthatareangledtotheleftand

tips that are angled to the right Square tips are used forgeneral parting off tips angled to the left are usedwhen youdonrsquotwanttoleaveapiponthebackendoftheworkandtipsangledtotherightareusedwhenyouwantacleanfaceonthefrontoftheworkThe parting off blade is oftenmounted upside down at the

backofthe lathecrossslideTheactionofpartingofftendstolift the whole cross slide slightly and forces the cross slidetightly into thematching dovetail whichmakes itmuchmorerigidIfthepartingofftooldigsinwhileinthebacktoolpostthetool tends to lift and push away from the work whereas in afronttoolpostthetooltendstodiginandpullintothework

Simplifieddiagramofpartingofftoolangles(A)straightpartingtool(B)angledtotheleft(C)angledtotheright

POWERREQUIREMENTS

Whenturningmildsteelorstainlesssteelwithanycarbidetoolthe machine horse power required is considerably more thanthat required forordinaryHSStoolsThe twomain reasons forthisarethatcarbidetoolsoftenhaveanegativerakeangleonthecuttingedgeasthistypeofedgelastsmuchlongerthanapositiveangle especially for intermittent cuts andbecause in

industrial use carbide tips are called on to remove largerquantitiesofmetalathigherspeedsandfeedsFor guidance on using tipped tools in the small workshop

wheretimeisnotasimportantasinanindustrialenvironmentIwould recommendusing twice the speedused fornormalHSStools and a fine feed of about 0002in (005mm) per rev as astarting point This can be adjusted up or downdepending ontheresultsThemaindifferencebetweenHSStoolsandcarbidetippedtools(eitherbrazed-onorinsertedtip)isthehorsepowerrequirementofthemachineinuse

Thispartingofftoolismountedatthebackofthelatheinaspecialbacktoolholder

SELECTINGTHECORRECTSPEEDSFORDIFFERENTMATERIALS

Overmanyyears through trialanderror cuttingspeedshavebeendeterminedthatgiveanoptimumtoollifebalancedwithadecent surface finish These speeds are normally quoted inlsquosurfacespeedinfeetperminutersquoSpeeds and feeds used on industrial machines where the

primary tools will have inserted tips will be a lot higher than

thoseusedinthesmallworkshopwhereHSStoolsarethenormThe accompanying table gives an idea of the speeds that

shouldbeused forvariouscommon typesofmaterial likely tobefoundintheworkshopThespeedslistedshouldbesuitableforbothturninganddrillinginthelatheForreaminguseabout25percentoftherecommendedspeedsThe table is a guide only and it is likely that the machine

speedsavailablewillnotbeexactlythoserequiredandyoumayhavetoresorttolsquonearenoughisgoodenoughrsquoSetthelathetothe nearest speed lower than indicated in the table for thediameterandmaterialbeingcutThiswillbefineforHSStoolsDouble the recommended HSS speed for carbide tools For

parting off use about 30 per cent of the recommended HSSspeed For form tools use about 50 per cent of therecommended speed for the initial cuts and then engage thecorresponding back gear (just switch to back gear leaving thebelts on the same pulley) and gently tap the handle until itreachesthefinishedsizeandallowittofinishthecutbyitselfYou may have to adjust the speed down if you get a lot ofchatter

Forturningcastironuseacarbide-tippedtoolrunningattheHSSspeedtoremovetheskinYoucanthenfinishtheturningwithaHSSsteeltoolifyouwishPlease remember if doing any work that might be

unbalancedstartoffslowlyandincreasethespeedabeltstepatatime

THEACTIONOFCUTTINGTOOLS

Basicallya lathe tool isawedge that is forced into theendofthe rotating bar to remove metal As long as the tool is fedforwardwhilethelatheisrotatingmaterialwillberemovedA typical right-hand turning tool has a cutting angle of 90

degreeslessthesideclearancelessthesiderakeThecuttingangle for this example is 90ndash10ndash10= 70 degrees This is theangle that is wedged into the work to remove the materialSoftermaterialswillhaveasmallercuttinganglewhilehardermaterials will have a larger cutting angle Tool angles varydependingonthetypeofmetalbeingturnedToolsforturningsofter metals usually have higher rake angles than thosedesigned for harder metals since a turning tool will normallyholditsedgeforlongerinsoftermaterialsBrassalthoughsoftusuallyhasnotoprakeonthetoolatallOther angles to be aware of are the top rake and the side

rake

CUTTINGTOOLSHAPES

The followingaresomeof thedifferent shapes thatyoumightfindusefulforgeneralturningandmetalremoval

Right-handknifeturningtoolAllrakeanglesare10degrees

Right-hand knife tool This is used for general turning andfacingofbarstockDependingontheworkyouaredoingyoumayfindaleft-handversionofthistooluseful

Typicalroughingtool

Right-handroughingtoolIthasaleadingangleandasmallradius on the tip of the tool This tool is used for fast metalremovalwherefinishisnottooimportantAgainyoumayfindaleft-handversionusefulAroughingtoolcuttingatanangletoabarwillremoveachip

widerandthinnerthanatoolcuttingat90degreestothebarThis improves tool life although you will have to square theturningupwithastandardknifetool

Typicaldouble-sidedroughingtool

Double-sided roughing tool It can turn towards the left orright It canalsobeusedasaplunge tool to removematerialfroma groove orwhere the component needs to be lsquowaistedrsquodown

Simplepartingofftool

Simple parting off tool This is suitable formostmaterialsYouwillprobablyneedalargeoneforpartingofflargediameterbarsaswellasasmalloneforpartingoffsmallcomponents

Internal(top)andexternal(bottom)screwcuttingtools

ScrewcuttingtoolThisisusedforcuttingscrewthreadsTheanglewilldependonthethreadyouarecutting60degreesformetric55degreesforWhitworthandBSFetc

Shallowboringtoolcapableoffacingacrossthebottomofahole

Boring and facing tool This toolrsquos unusual shape will befound very useful when recessing a large bore It will plungestraight intoasmalldrilledholeandwillalso face rightacrossthebottomoftherecess

Double-endedchamfertoolchamferingadiameter

Double-ended chamfering tool It has 45 degree angles atbothendssoitcanbeusedtochamferexternaldiametersandinternalbores

Double-endedchamfertoolchamferingabore

Othershapescanbeusefulbutthetoolsshownhereshouldbesufficienttogetyougoing

BORINGTOOLS

Boring tools are used to clean up a previously drilled holepossiblytomakeitruntruebutmorelikelytoensuretheholeistothecorrectsizeTheyarenormallylongerthanordinarytoolsandtendtostickoutfurtherfromthetoolholderHSStoolsaresuitableformostusesCarbideinsertedtipboringbarsarealsoreadilyavailableandarethebestbetforturningcastironinthesmallworkshop

HSSboringbar

For really small holes down to2or3mm indiameter solidHSSandcarbideboringbarsarereadilyavailableAlthoughtheyarenotcheaptheywillbefoundveryusefulandquicktouseAnothermethodofboringahole is tousea longseriesslot

drillasaboringtoolInuseclamptheshankinthetoolholderwiththepointatcentreheightmakingsuretherestoftheslotdrillisclearofthesideoftheboreYoucanthenrunitthroughtheboreinasimilarmannertoastandardboringbar

Asmallcarbideboringbarinsertedintoamildsteelshank

PARTINGOFFTOOLS

PartingofftoolsprovideaquickwayofcuttingoffworkfromtheparentbarThereisrarelyanyneedtoworryaboutcuttingthecomponentofftothecorrectlengthtogetagoodfinishAslongasthecomponentislongerthanrequireditcanbeputbackintothe chuck or a collet and the parted off face can be faced tolengthorotherwiseworkedonThepartingofftoolcuttingfacecaneitherbesquareoritcan

beangledtotheleftorright(seepage43)Thesideofthepartingofftoolcouldevenberadiusedsothat

it forms a radius on the end of the next component orchamferedtoformalead-inedgeforthenexttool

CUTTINGLUBRICANTS

Tomake cutting tools cut easily and to prolong their life it issometimesbesttouseacuttinglubricantForsteelIpreferneatcuttingoilItlubricatesbutisnotidealforcoolingtheworkIn industry coolant is normally used This is oil that has an

additivetomakeitsolubleinwaterMostsolubleoilswilldobutthe synthetic ones tend to sting your hands if you have anyopen cuts I would not recommend using soluble oils on thehome workshop lathe as I think they tend to wash thelubricating oil off the slideways and can encourage rustHowever this ismypersonalpreferenceandmanypeopleusesolubleoilinthehomeworkshopwithoutanyproblemsOil is suitable for use when cutting steels mild steels

stainlesssteelsandhighcarbonsteelssuchassilversteelThebestlubricantwhencuttingaluminiumisparaffinItstops

thealuminiumfrombuildinguponthecuttingtoolBrassandcast ironarenormallycutdryWhenturningcast

ironona lathe if the latheisfittedwithasolubleoiltankthecastirondustwillhaveanaffinityforthesolubleoilIfthelatheisthenusedonaluminiumthefreecarboninthecast ironcancontaminatethealuminiumwithblackstreaks

Inormallyplacetheoilorparaffininasmalldish(actuallyacatordogfoodbowl)andapply itbyhandwithasmallbrushThisdoesallIneedThenextchapterlooksatgrindinglathetools

4SharpeningToolsandHoldingThemintheLathe

ThenexttaskistogrindasetofusefullathetoolsThe first thing you will need is an off-hand grinder The

grindercanbeadangerousmachineso itshouldbeusedwithcare Eye protection must be worn the guards should becorrectlyfittedandtheremustbeadequateilluminationIdonrsquotlike using a grinder in a small workshop as the grinding dustflies everywhere and canget onto themachine slideways andtools generally making the workshop dusty and dirty Ifpossible set up thegrinder in a separate areaaway from theworkshopIhavemygrindermountedonafoodchoppingboardso I can carry it outside to use This has the addedbenefit ofdaylight although you are dependent on the weather or youmightneedtouseitafterdark

Theguardofthisoff-handgrinderhasbeenwidenedtoacceptarecessedwheel

GRINDINGWHEELS

IthasalwaysbeenstatedthatyoushouldnevergrindatoolonthesideofthegrindingwheelSofollowingthistheorywewillbeusingarecessedwheelwhereitswidthismuchthickerthanthepartofthewheelusedtoclampthewheeltothegrinderIstruggledtofindarecessedwheelof6in(150mm)diameterandfinally found a 60 grit grinding wheel on a personal visit toAxminster Power Tools in Devon (I could find only an 80 gritwheel in theircatalogue)Thewheels I like touse forgrindingare A60K5V if I can get them and I prefer the white wheelsdesigned for the harder tool steels rather than the grey orbrown wheels which are more suitable for softer mild steelsThedesignationbreaksdown like thisA stands foraluminiumoxide 60 is the grit size K is the hardness (I J and K beingmediumhard)5 is thestructure(thespacebetweengrainsofgrit) and V is for vitrified the method of bonding the grainstogetherTheKandthe5canvaryabiteitherwayandthegrit

shouldbe4660or80with60beingpreferredThe80gritisabitfineandwillclogupquitequicklySo-called green grit wheels made from silicon carbide are

available for sharpening carbide tools They are usually softerthanaluminiumoxidewheelsinordertoallowthegrittobreakdownbeforethewheelbecomesglazedfromgrindingthemuchhardercarbide

Witharecessedwheelyoucancutontheouterfaceoftherecessedsideofthewheel

TestingtheWheel

The first thingyoushoulddowhenbuyingawheel is tomakesurethat it is ratedatasufficientlyhighspeedfor thegrinderon which it is to be used Off-hand grinders usually run ataround2900rpmsoyouwillneedawheelratedtoatleastthatspeed it is all the better if the grinding wheel is rated at ahigher speed than the grinder Care should be taken whenhandlinggrindingwheelsastheyarequitefragileifknockedordropped A grinding wheel should only be purchased from areputableengineeringsupplierSupportyourgrindingwheelona piece of wood and tap the wheel gently with a plasticscrewdriver handle or similar The wheel should lsquoringrsquo if itsoundsdullitshouldbebrokeninhalfandeitherthrownawayorusedontheworkbenchasasharpeningstoneNeverthrowawheelawaywithoutbreaking it into twoyouneverknowwho

mightgettheirhandsonit

Thistoolrestwasdesignedtosharpenplaneironsandchiselsbutitisfineforlathetools

Amoderndigitalanglegaugeisidealforsettingthetoolrest

MountingtheWheel

The wheelrsquos bore should be the same as the spindle of thegrindingwheelOften theborewillbe largerandyouwill then

need some plastic spacers to reduce it Spacers should bereadilyavailable fromyour localengineeringsupplierYoucanturn thespacers fromplastic if youcanrsquotbuyany ready-madeonesAt each side of the wheel you should fit a paper washer

thesearemadeofblottingpapertypematerialandwillprobablyhave been supplied already stuck on the wheel The grindershould have twometal flanges one to fit at each side of thewheel Both flanges should be the same diameter These willhold the wheel true and spread the tightening load on thewheelThegrinderwillhavetwodifferent threadsontheendsof its spindle The right-hand side of the grinder will have aright-hand thread and the left-hand side will have a left-handthreadThedifferentthreadsaretostoptheclampingnutsfromunscrewingwhenthegrinderisrunningTofitthewheelremovetheguardandundothenutRemove

the metal flange and then the wheel Make sure the flangesdonrsquothaveany remainsof theoldpaperwasheron themPutthenewwheelontothegrinderspindle(rememberthespacerthepaperwashersandtheflangesateitherside)andscrewthenuthand-tightFinallyholdthewheelgentlyandgivethenutapinchupwithaspannerYoudonrsquotneedtoover-tightenthenutjustsufficiently tostop thewheel fromcoming looseRefit theguard and spin thewheel by hand to ensure it is not rubbinganywhereNowwearealmost ready to switch thegrinder onBeforedoingsohoweverputonyoureyeprotectionandstandtoonesideofthegrindersoyouarenotinlinewiththewheelshould it burst Then switch the grinder on All should be fineandthewheelshouldberotatingsafely

TOOLREST

Theworkrestsuppliedwithanoff-handgrinderisusuallyjustabitofbentsheetmetalboltedonItisusablebutonlyjustI recently purchased a ready-made tool rest as a basis for

makinganimprovedgrindingrestThiswasoriginallydesigned

forsharpeningplanebladesandchiselsforwoodworkingbutitmakes an ideal rest for sharpening lathe tools It is made ofaluminiumandisfullyadjustableforangleThebestmethodofsetting the rest to the correct angle is to use a digital anglegauge These are now very cheap and are readily obtainableThepositionoftherestinrelationtothegrindingwheelcanbeadjusted on its sliding base Many designs for tool rests havebeenpublishedandyoucouldmakeoneofthoseinsteadifyouwishtosavemoneyThetoolclampassupplied isdesignedtoclampplane irons

andchiselssothisneedstobechangedLathetoolsneedtobepresented to the grinding wheel at the correct angles If youdonrsquot have a digital angle gauge this can be achieved usingsimpleguidesmadefromanglesheetmetalandsomescrewsIused gauge plate made from a high carbon steel with anaccurategroundfinishthatcanbehardenedandtemperedbutmild steel would be perfectly suitable if you donrsquot have anygaugeplateavailableYouwillfindaprotractorusefulyoucangetasteelonewith

an adjustable blade for a reasonable price The protractorwillbeusedtosetthetoolanglethatisgroundonthetools

Sheetmetalprotractorsareavailableverycheaply

LATHETOOLGEOMETRY

LathetoolsneedtobegroundtocertainanglesbuttheanglesdonrsquothavetobeexactFormosttoolssomewherehandywilldounless you are grinding a form tool to a particularly accurateshapeIthasbeennormalforbookstoshowtheanglesontoolsas used in a production environment where tools will ideallyhavealonglifeoftenthislifeiscalculatedaslastinganeight-hourshiftsothetoolonlyhastobesharpenedandresetonceadayInthehomeworkshopwecan increasethesecuttingangles

andgetbettercuttingattheslightexpenseofshortertoollifeWehavealreadyexplainedtheshapesof the tools thatyou

willfindmostusefulToolanglesareknownbytechnicaltermstop rake front rakeside rakeandback rakeThe rakeanglesvary depending on thematerial to bemachined but a set ofstandardtoolswillgetyoustartedSomeoftheaccompanyingphotographsareactuallyoflarge-scalewoodenmodels

Theleft-handtoolissuitableforbothfacingandturningtheright-handtoolissuitableforturningonly

Left-handsideofthefacingandturningtoolshowingthefrontandtoprake

Topofthefacingandturningtoolshowingthefrontandsiderelief

Left-handsideoftheturningtoolshowingthefrontclearanceandthetoprake

Topoftheturningtoolshowingthefrontandsideclearanceandthetoprake

GRINDINGATOOL

WhengrindingHSStoolstrytokeepthemascoolaspossibleIfan HSS tool becomes too hot and is then quenched in waterminutecrackswillformonthecuttingedgesThesecrackswillmakethetoolcuttingedgebreakdownveryquicklywhenusedThe best practice is to grind a little bit off the tool and thenquenchitwhileslightlywarmDonotletthetoolgethotdipitin thewater little andoften This should ensure the tool edgedoesnotbreakdowninuse

GrindingYourFirstTool

Most angles can be ground by using the tilting table whileothersmayneedtobefixedinrelationtotheperipheryofthegrindingwheelThefrontandsideofthetoolcanbegroundbytippingthetableatthecorrectanglewhereasthetoprakecanbegroundontheperipheryofthewheelThegrinder should first be switchedoff andunplugged Set

thetoolresttotherequiredangleusingthedigitalanglegaugeoranangletemplateandtightenuptherestBefore switching on the grinder ensure that everything is

freetorotatebyspinningthegrindingwheelbyhandIf all is well put on your safety glasses and switch on the

grinderPlacethetoolonthetoolrestupagainstthesideoftheprotractor Slide the tool along the table until it reaches thegrindingwheel andmetal starts to be removed Slide the toolbackwards and forwards slowly along the restwhile putting alittle light pressure on the tool so that it continues to pressagainst the grinding wheel When you have removed a smallamountofmaterialcoolthetoolbitdownAtnotimeallowthetool bit to get hot Continue grinding until you have removedsufficientmaterialfromthetoolbit

Thegrindingrestissettothecorrectangleof10degreestogrindtheendofthetool

Grindingthefirstangle

TurnthetooltotheotherangleanddothesamesothatnowboththefrontandsideclearanceangleshavebeengroundThis toolwill be enough for brass but for steelwe need to

grindthetoprakeWhengrindingthetoprakeonaright-handtool the slide rest needs to be higher than the centre of thegrinding wheel so that it grinds the tool at approximately 10degrees

Thefirstanglehasbeenground

You have now ground your first lathe tool The tool asreceivedfromthegrinderwillbetooroughtousehoweversoyouwillneedtohonethecuttingedgesYoucandothisonanoilstone(usedwithfineoillike3in1)orwithadiamondlaporusing a combination of the two Lightly lap the front and sideclearanceanglesuntilyougetagoodfinishand lightlyhoneaverysmallradiusonthetipofthetoolFinallyhonethetoprakeangleandyourtoolisreadyforuse

Grindingthesecondangle

Thesecondanglehasbeenground

AllofyourHSSturningtoolscanbedoneinthiswayOnlytheangleswillvaryandthesecanbesetusingadigitalanglegaugeandprotractorAnoccasionalhonewillresharpenyourtoolsaslongasyoutreatthemwithcareA similar range of HSS tools and a parting off tool all with

zero top rake shouldbeavailable if youwill be turningbrassUnless you are doing quantity production one tool holdershouldbesufficientforbrassAsatoolforbrasshasnotoprakeandyouwouldnotnormallygrindthetopawayaslongasyoubuy tool steel of the same size the tip height will remain thesameYoucanthenusethedifferenttoolsinoneholderwithouthavingtoresettheheight

MACHININGCASTIRON

Carbide-tippedtoolsareidealformachiningcastironAsimplebrazedupcrankedtoolwithasmallchamferonthenosewilldoforbothturningandfacingcastironcomponentsThemainuseof this tool will however probably be truing up the faceplatethat comes with the lathe The large diameter combined withtheintermittentcutovertheboltgrooveswoulddestroyanHSStoolinafewsecondsAsmalltippedboringbarwillbeidealfor

taskslikeboringcastironcylinders

Grindingthethirdangle

Asimplediamondlap

Thethirdanglehasbeenground

Tosharpentippedtoolsyouneedadiamondwheelorifyouwant to remove large amounts of carbide a silicon carbidewheeloftencalledagreengritwheelowingtoitsusualcolourSilicon carbide wheels are much softer than aluminium oxidewheels as they need to break down faster to present newsharpergrainstothecarbidetoolAdiamondwheelisonlydesignedtolightlylapatippedtool

itisnotsuitableforremovinglargeamountsofcarbide

Diamondcupwheel

TOOLHOLDING

Smallerlathessuchasarefoundinmostworkshopsmayhaveatopslidewithatoolclampforindividualtoolsablockwithasingle slot to take the tool a four-way turret (or sometimes athree-way)oraquick-changetoolblockandholdersetThereisalsotheso-calledAmericantoolpostwhichisaroundbarwitha slot through it and a bolt in the top to clamp the tool ItusuallycomeswithmatchingdishedwasherstoadjustthetoolheightThistypeisnolongerverycommononlathes

Quick-changeToolPost

Themostversatiletoolholdingsystemisthequick-changetoolblockwithmatchingholdersThedrawbackwiththissystemisthe cost of extra tool holders you need quite a few one foreachtoolThequick-changetoolblockmountsonthefrontofthelathe

normallyontopofthetopslide(Blockscanbefitteddirectlyon

thecrossslidebytheuseofaraisingblocktoaidrigidity)

Quick-changetoolblock

Each holder is set up with its own particular tool The toolholderscanbe individuallysetso that the turning tool isdeadoncentreheightandispresentedcorrectlytotheworkpiece

Quick-changetoolholder

Quick-change tool holders are available with a straight cutslottotakestandardsquareshanktoolholderswithastraightcutwiththeadditionofaVeecut-outinthebottomforusewithroundtoolssuchasboringbarsandasafrontpartingoff tool

holdertotakeahighspeedsteelpartingoffbladeRearpartingoff tool holders are available to take an inverted parting offbladeeitherahighspeedsteelbladeoran insertedtipbladeLeft-handed and right-handed extended tool holders are alsoavailableandmayoccasionallybequiteusefulThetoolblock isnormallymountedonthetopslidebutyou

cangetraisingblockstouseinsteadofthetopslideThismakesthetoolholderblockmuchmorerigidAbackquick-changetoolblockwillneedmountingonaraisingblock

Backofaquick-changetoolholdershowingthedovetailtypeofmounting

Right-handandleft-handextendedtoolholders

StandardtoolholderwithaVeetotakeroundtoolholders

Frontpartingofftoolholder

ToolClamp

Satisfactoryworkcanbedonewithatoolclampedontothetopslideusingshimsteel toset thecentreheightof the toolThemaindrawbacksarethatyoulosethepositionofthetoolwhenyoutakeitoffthetopslidetofitthenexttoolandyoualsolosetheaccuratecentreheightofthetoolunlessyoukeepthetoolandshimstogetherIfyouaremakingonlyonecomponentthisisnotaproblembutitisanuisanceifyouaremakingabatchofmatchingcomponents

Simpletoolclamp

Single-slotBlockToolPost

AblocktoolpostisoftensuppliedwiththecheaperlathesThetoolpostisliterallyablockofmetalwithaslotcutinittotakethe turning tool It is relatively easy to set the tool up at thecorrectcentreheightbyusingvariousthicknessesofshimThisisfineforthebeginnertoturningwhoisjuststartingoutbutitisbesttoreplaceitwithafour-waytoolpostoraquick-changetool post You could of coursemake several block tool postsandkeepeachonesetwithadifferenttool

Four-waytoolpost

Backtoolpost

Four-wayToolPost

Four-wayToolPost

Thefour-waytoolpost isagoodcompromiseona latheasyoucansetfourtoolsintheturretandrotateeachoneintopositionas needed This speeds up production and is a lot faster thanusingasimpletoolclampThedrawback isthatthetoolsstickoutof the turret fourdifferentwaysandyoumightcatchyourhandonasharp toolAsimple ratchetstopensures thateachtool repeats its position when the tool post is rotated so theworkisaccuratelyturnedeachtimethetoolisusedAduplicatefour-waytoolpostwithtoolsforbrasswillspeedupproductionevenmoreCastingsareavailabletomakeyourownthree-waytoolpost The three-way toolposthas theadvantageofbeingable to get close to the work when you are turning betweencentresFor the front tool post I would recommend right-hand and

left-hand roughing tools right-hand and left-hand finishingtools a tool groundup to face barswhile using a half centreand a Mini Thin inserted tip grooving tool with grooving andparting off inserts You will also need large and small boringbarsbothHSSandwithinsertedtipsTheHSStoolsshouldbegroundupforuseasgeneral-purposeturningtoolsformildsteelandsimilarmaterialsThecarbideinsertedtipboringbarshouldbefineforcastiron

BackToolPost

You can fit a quick-change tool block to theback of the crossslideaswellasthefrontSpecialholdersareavailabletotakeaHSSparting off blade or an inserted tip parting off blade Thebladewill be angleddown to give top clearancewhenpartingoffTheseback-mountedtoolblocksareveryhandyastheycanalsobefittedintotoolholderswithafacingtoolorachamferingtoolFor a back tool holder set-up I would recommend an HSS

partingoffbladeafacingtoolforcastironandadouble-ended45-degree chamfering tool that can be mounted parallel with

the chuck or at 90 degrees to it This set-upwill allow you tofaceaworkpiecechamfertheoutsidediameterandortheboreandpartitofftolengthThenextchapterlooksatholdingworkinachuck

5WorkholdingintheChuck

This chapter covers the different types of chucks how to usethemandsetupworkinthemaccurately

Aself-centringthree-jawchuckfittedwithlsquodrilljawsrsquoNotetheexternaljawswhichareinterchangeablewiththedrilljaws

USINGCHUCKS

Themostusefultoolsforworkholdinginthelathearethree-andfour-jaw chucks The three-jaw chuck is usually of the self-centringvarietythistypeofchuckcomesasstandardwithtwosets of jaws The first set of jaws are known as inside or drilljaws as they are most useful for holding round and hexagonbarsTheother setof jawsareoutside jawswhichholdworkusuallyindiscformontheoutsideSelf-centringmeansthatwhenyouinsertabitofbarintothe

chuck and turn the chuck key the chuck centralizes theworkpieceas it tightensup It isunlikely to runperfectly truebutitshouldruntruewithin3or4thouYou can also purchase soft jawswhich are exactly as their

namesuggestsYoucan thenbore themout to fit thework Ifyouborethemonthelatheyouaregoingtousethemontheworkwillrundeadtrue

Asetofsoftjawscanbeturnedorboredtosuittheworktobeheld

Aself-centringfour-jawchuckThesealsocomewithexternaljawsandsoftjawsareusuallyavailable

Self-centring four-jaw chucks can be used for square barsTheyarealsousefulforholdingroundbarswithmoregripthanathree-jawself-centringchuckSoft jawsarealsoavailableforfour-jawself-centringchucks

Afour-jawindependentchuck

Youare howevermuchmore likely to comeacross a four-jaw independent chuck than a four-jaw self-centring chuckIndependent means that the jaws can be moved individuallyand the jaws can also be reversed one two three or four ofthemdependingontheworktobedone

Abaseplatecastinginafour-jawindependentchuck

Wewillfirstlookatthethree-jawchuckThebestmethodofmaking a component in one of these is if possible to turn itcompletely at one set-up If you put a piece of bar into thechuck face the end centre drill drill and ream it skim thediameterandpartitoffitshouldbeconcentricalloverThisisbecausewehaveturneditallatthesamesettingwithouttakingit out of the chuck If we need to machine the other endhoweverwhenwe turn it roundandput it back in the chuckthechancesareitwillnotruntrueThis iswherethe four-jaw independentchuckcomes inYou

canput thecomponent intoa four-jawchuckandset it to runtrueusingthedialtestindicatorAnyworkyoudoonthepartedoff end should then be concentric with the rest of thecomponentWhensettingworkinafour-jawindependentchuckfor a second operation use some thin shimbetween the jawsandtheworkpiecetoavoidmarkingtheworkWorkisoftenheldinafour-jawchuckbecauseitisacasting

anoddshapeorsquareandsowonrsquotfitintoathree-jawchuckIf thework just requires tobe faced flat rightacross the facethereisnoneedtosettheworkrunningradiallytrueItshouldbe near enough on the centre line as long as the work is

reasonablybalancedYou could of course put the component into a three-jaw

chuckbyfittingsoft jawsandmachiningorboringthemouttotake the component This is the best option ifmaking severalcomponentsthatneedtobeidenticalbutifyouonlyneedoneor two components a four-jaw independent chuck will be thequickestmethodofmachiningthemLargerdiameterscanbeheld ina three-jawchuckbyusing

theoutsidejawsThesehavealargeradiusontheinsideofthejaw ifthisradiusis largerthantheworkpiecethejawsshouldnot tend to dig into the work and mark it Outside jaws areuseful forholding components like small flywheels locomotivewheels and chuck backplates when machining the bores ofholesorwhenmachiningacrossthefaceWhenmachining thindiscs it isuseful toputsomepacking

behindthedisctomakeitstandproudofthejawsTostopthepackingflyingoutwhenthemachineisrunningmakeasetofthree or four packing pieceswith grooves at each end and fittensionspringstothemTheyshouldallbethesamediametersothatthebackoftheworkisparalleltothechuckThelengthand grooves can vary slightly as they donrsquot affect theparallelismTheyarequickandsimpletomakesoacoupleofsets of different diameters should find their way intoeverybodyrsquostoolbox

AlthoughmostlathechuckkeyshavesquareendstheyareoftenofdifferentsizesKeepeachkeywithitsownchuck

ChuckKeys

I have alreadymentioned that the chuck key should never beleftinthechuckwhenitisunattended(seeChapter2)PutthekeyintothechuckuseitandputitsafelyawayassoonasyouhavefinishedwithitIfyouswitchonthelathewiththekeystillinthechuckyoumightneedatriptothehospitalDonotuseexcessive forcewhenyou tightenup the chuck

Do not use a piece of tube a spanner or anything else as alever thechuckkeyon itsownshouldbesufficient to tightenthechuckontotheworkWhenusinga four-jawchuckasmallchuckkey littlemore

thanaknurledknobwithasquareoncanbeusedtoadjustthejawsinandoutpriortotighteningupwiththeproperchuckkeyThiswill save timeover adjusting the jawswith a large chuckkeyTo turn the independent four-jaw chuck jaws round a

carpenterrsquosbracewithapieceofsquarebarinittofitthechuckwillmakeshortworkofreversingthe jawsbutdonrsquotuse it forthefinaltighteningasitisliabletostrainthejaws

STARTINGTOTURN

Before going any further you need to learn how to do basicturningFor thisyouneed toput the three-jawchuckonto themandrelStartbycleaningthemandrelwithacleanbitofragorsimilar(Ikeeparollofpaperkitchentowellingintheworkshop)Nowyouneed toclean thechuckrsquosboreand threadusing thetwotoothbrushmethod(seeChapter2)BoththemandrelandthechuckshouldbecleanbeforeyouattempttofitthechucktothelatheSelecting and grinding turning tools has already been

discussed (see Chapter 4) so by now you should have acorrectlygroundturningtoolsuitableforroughingoutapieceofsteelbar

Barwithapiptoolaboveorbelowcentreheight

MakingaToolCentreHeightSettingGauge

Thistoolneeds itscuttingedgesettothecentreheightofthelatheThereareseveralwaystodothisbutoneoftheeasiestiswith a home-made height gaugeWhen starting out this is achickenandeggsituationyouneedtomakethegaugetosettheheightbutyoualsoneedatoolsetatthecorrectheighttomakethegaugeThesimplestwaytoovercomethisproblemistosetthelathe

tooltotheapproximatecentreheightandtakeacutacrossthefaceofthebarDependingonwhetherthereisapipremainingon theendof thebaryoushouldgetan ideahow farout thetoolheightisIfthereisnopipthismeansthetoolisoncorrectcentre height or too high A pipmeans the tool is too lowOfcourse you may have been lucky so try dropping the toolslightly until a pip remains You can then raise the tool a fewthouatatimeuntilthepipdisappearsThetoolshouldthenbeoncentreheight

Barwithnopiptooloncentre

Nowthatthetoolisatcentreheightyoucanmakeasimpleheight gauge Turn a piece of bar down to as close to frac12in(12mm)asyoucangetandleaveitinthelathechuckMeasurefromthetopofthecrossslidetothetopofthebarwithacheapheightgaugeLowertheheightgaugebyhalfthebardiameterTheheight

gaugeshouldbeexactlyonthelathecentrelineMakeanoteofthisdimensionWe now need to look at how to turn a bit of bar to an

accuratediameterWhenturningabartosayfrac12in(12mm)youneedtostartwithsomethingslightlylargerInthiscasethiswillbe⅝in(16mm)diametermaterialasthisisastandardsizeCutapieceofmaterialabout2in(50mm)longandputitinto

thechuckwithabout1in(25mm)stickingoutSkimtheoutsidedown to about 0510 thou or 1225mm which is 10 thou(025mm) above the size required (You should be aware thatmosthobbylathedialsremovetwicewhattheysayaonethoudivisionforexamplewillusuallytake2thoufromthediameterLargercommercial lathesaremuchmore likelytotakeoffonethoupergraduation)Nowtakesmallcutsuntilalmosttosizeusingpowerfeedif

you have it andmaking sure you knock the feed off before ithitsthechuckStopthelatheandwindthecarriagetothestart

of the bar Take another cut at the same setting andmake anoteofthediameterTakeanothershallowcutbutthistimegoonly about frac14in (6mm) along the bar knock the feed off andturn the lathe off Move the carriage towards the tailstock sothat you can measure the bar Continue making this cut andmeasureuntilthesizeiscorrectThenrunthetoolalongthefulllengthof the jobWindthecarriagebacktowardsthetailstockand take a finishing cut or two at the same setting ThediametershouldnowbetheexactsizerequiredIt is not difficult to turn accurately it just takes a little

patienceandpracticeThemoreturningyoudotheeasieryouwill find it is to hold accurate limits If you turn everythingaccuratelywhetheritneedstobeaccurateornotyouwillsoonlearntoturnwithinathouorsowithoutanyproblems

Measuringtheheightofthebarabovethecrossslide

Now we need to make a tool height setting gauge Cut alengthofbarjustoverthedimensionsyouwrotedownandfaceone end turn it round in the chuck and face the other endMeasurethelengthandfindouthowmuchyouhavetotakeoffit to give the dimension you want Put the bar back into thechuck and bring the tool up to the face of the bar Lock thecrossslideFacethebartolengthbyusingthetopslideindexmovingforwardsafewthouatatimeuntiltherequiredlength

is reached Younowhavea tool height settinggauge suitableforthefrontandreartoolsIf you have an inverted Vee bed lathe or if for any reason

youcanrsquotusetheheightgaugeflatonthebedyoucanputtheheightgaugeonaplateon topof the lathebedwhileyouaresettingthetoolheight

Settingtheheightgaugetothelathecentreheight

Settingtheheightofthetool

Usingthesettinggaugetosettheheightofthereartool

TurningtoaSpecificLengthandDiameter

Nowwewill turnabarwithastepon theendToensure thatthestep isthecorrect lengthwewilluseabedstopThiscanbe as simple as a block clamped to the lathe bed to stop thecarriage moving any further I use a simple home-made bedstopthatdoesallIrequireSetthebedstopthenmovethecarriageuntilittouchesthe

stop and lock it Wind the top slide so that the tool is justtouching the end of the bar and lock the carriage For thisexercise we will make the step 16mm long and 12mm indiameterWindthetopslidealong159mmWecannowroughout thestepateachendTurn theenddown toabout02mmabove the finisheddiameterbywinding thecarriagebackandforthYoucanusethe fine feedbutmakesureyouknockthefeed off before the carriage reaches the stop and finish up tothestopbyhandWindthetopslidealongtheremaining01mmto12mmandfinishthediametertosizeandlengthtakinglightcuts as previously Donrsquot forget to clean up the face of theshoulderyouhavejustturnedIfyouneedtouseabedstopatthetailstockendofthelathe

asimplemethodofdoingthisistouseabarplacedonthelathe

bed against the tailstock The bar acts as a stop when thecarriageiswoundbacktowardsthetailstockThistailstockendbed stop is useful when you are turning a groove in acomponentandyouneedstopssetatboth theheadstockandtailstockendsofthelathe

Ahome-madebedstop

TurningWorkontheOutsideoftheInsideJaws

Theoutsideoftheinside(drill)jawsareusefulforturninglargerdiameterwork that is too large to fit inside thedrill jawsThiswillmostoftenbe in the formofa flywheelcastingFlywheelswithsixspokesareidealforturninginathree-jawchuckasthespokes can fit between the chuck jaws Ideally you need totighten up the flywheel until it is tight but not so tight as todistorttherim

TurningasteponabarusingthestopThebarisheldinthethree-jawchuckandsupportedwiththetailstockcentre

Ausefultailstockendbackstopmethod

Holdingaflywheelinathree-jawchuck

Holdingaflywheelintheoutsidejaws

To ensure concentricity you should do as much work aspossibleonthecastingatthesametimeYoushouldbeabletoturntheoutsiderimofthecastingfacetherimfacethebossand drill bore and ream for the crankshaft all at the samesettingAllyouneedtodothenistofittheoutsidejawsreversethecastinginthechucktapitgentlybackontothestepsoftheoutsidejawsandfaceacrossthesecondsideoftherimandthehubUseabitofshimtoprotecttheflywheeldiameterItdoesnotmatter if the flywheel runs exactly true or not as you areonlyfacingitparallelandtowidthnotturninganydiametersto

size

UsingtheSoftJaws

Soft jaws are very useful when a component has to run deadtrue in the jaws for example when making something like agrindingspindlewhereconcentricityisimportantSoftjawslikelytobefoundinthehomeworkshoparesimple

rectangles of steel with the scroll and groove formed directlyintothesoftjawsAnothertypeofjawyoumaycomeacrosshasa grooved pattern in the main jaws that matches a similarpattern in theactualsoft jawsThesoft topsof these jawsareusually interchangeable They are more likely to be found onlarger chucks but you could make your own version for thesmallersizesofchuckifyouwishThemain use of soft jaws is for second operationwork for

examplewhenyouhaveturnedacomponentcomplete fromabitofbarandparteditoffNowyouneedtoholdthecomponenttruetofinishoffthesecondendYoucandothisbyboringoutthechuckjawstotheexactdiameteroftheworkpieceToborethesoft jawstheyshouldbetightened inthesame

direction as they will be tightened in use so that they areoperatingonthesamepartofthechuckscrolleverytimeIfyouhaveathincomponenttomachinefitthesoftjawstothechuckandtightenthejawsontoabitofbarheldinthechuckBesureto leaveenoughspace in frontof thebarsoyoucanbore thejawstofitthework

BoringsoftjawstofittheworkThejawsareclosedontoanoddmentofbartoturntheshallowregistersothatittakesthework

AlwaysusethesamechuckkeyholewhentighteningupthejawsThisappliestoanythingyoudowithaself-centringchuckStampacrossoracentrepopmarkagainstoneof the jaws IsuggestdoingthisnexttojawNo1butanyonewilldoaslongas you always use the samemarked hole Youmight as wellmarkallyourself-centringchucksinthesamemannerCarefullyborethejawstotheexactdiameteroftheworkto

be machined Try to get it exactly on size Undo the jawsslightly remove the bar and replace it with the workpiecewhichshouldnowrundeadtrueAusefulmodificationtothesoftjawsistodrillandtapahole

inthemiddleofthejawsandfitanAllenscrewtoeachholeIfyouwant toholda longbar in thesoft jaws it isnoweasy toboreallthewaythroughthejawsratherthanjustboringastepor part way through All you need to do now is find a disc ofmaterial to put into the chuck ensuring there is sufficientmaterialleftontheinsideedgesofthechuckjawstoborerightthroughtotakethebar

Holdthedisconthescrewheads ifnecessarydrillthediscbeforeboringBorerightthroughthediscandthejawsuntilyouarenearlytosizeatwhichpointyoucanborethroughthediscand test the resultingborewith theworkpieceMakesureyouclean the bore thoroughly before trying the workpiece sinceloose dust can make the hole seem smaller than it really isWhentheworkpieceenterstheborefinishboringrightthroughthe jawsgo througha coupleof timesat the samesetting totakeoutanyspringintheboringbarYoucannowremovethedisc clean the jaws and put the workpiece right through thechuckcheckingthatitrunsdeadtrueThisoperationmaysoundtimeconsumingforasingle item

but if you have several components to make it will save aconsiderable time on setting up each bar individually to runtrue

BoringsoftjawsusingaringThesoftjawshavethreeAllenscrewsthatarecloseddownontotheringwhileboring

TurningtheoutsideofthesoftjawsusingaringThesoftjawshavethreeAllenscrewsthatareopenedupontotheringwhileturning

NowthescrewsareinplacewecanworktheotherwayroundandholdcomponentsontheoutsideofthejawsTodothisyouwillneedaringofasuitablesizeontowhichyoucantightenthejawswith the jaw loading acting outwards so any componentyouputontheoutsideofthejawswillberunningconcentricallyThiswill be ideal for itemssuchas tractionenginewheel rimsandotherlargehollowortubularworkpiecesOne other use for soft jaws is to hold irregular-shaped

components Put a piece of bar into the soft jaws and bore aholeofanysizeand thencleanup theboreso thatallof thejawsare true Transfer the chuck to themillingmachine tableandclampitdownUseatestindicatortocheckthattheholeinthechuckistrueYou can now mill a nest to take any irregularly shaped

component confident that when the chuck is returned to thelatheitwillberunningtrue

Plungertypedialtestindicator

Levertypedialtestindicator

DialTestIndicators

Therearetwomaintypesofdialtestindicatortheplungertypedial test indicator as its name suggests works on a plungerprinciplewhilethelevertypedialtestindicatorhasastylusonthe end The lever stylus is usually ball-or pear-shaped and isfixedtothedialtestindicatorwithafrictionfitmeaningthatitcanbemovedupanddownontheendofthedialtestindicator

throughawidearctoputitintothebestpositionforuseThe plunger type dial indicator usually has a maximum

plungermovementoffrac12in (12mm)butplungermovementsofupto2in(50mm)areavailableTheplungertypedialindicatoris non-reversing and needs an adaptor to enable it to clockholes true Instead of a stylus it has an interchangeable endoften with a ball fitted various interchangeable ends areavailableoryoucanmakeyourownThe lever dial test indicator has a much smaller range of

travelarangeof0008in(02mm)isverycommonItisusuallyeither self-reversing (itmoveswhen in contact with theworkdependingonwhichwayitismoving)oritmaybereversedbyusinga lever on the sideof thedial test indicator both typesarequite commonSince the stylus isdelicate combinedwithitslimitedtravelrangeyoumustbeverycarefulnottobreakitAplungerdialindicatorcanbeusedasadirectreadoutofthe

travel and will be found to be very accurate Owing to therelativelylongtravelifyouwantedperhapstooffsetthecentreofabitofbar in the four-jawchuckby0125in (318mm) thiscanbedonebyturningthechuckbyhandandsettingthebaruntil the indicator travel shows 0250in (635mm) which is0125in (318mm) offset The lever dial test indicator is of nouseforgivingdirectreadingslikethisbutshouldbeusedasacomparatorwherethereadingtakenisforexamplezeroatallpointsofthetravelThedial test indicator is usuallymounted on amagnetic or

vacuum base but is sometimes fixed to a block that can beclampedtothelathemostoftenonthecrossslideSometimesthedialtestindicatorcomesasacompletekitincludingvariousmountingcomponents

Clockingtheendofacastinginafour-jawchuck

Four-jawChuck

To set thework up in an independent four-jaw chuckwe firstneed to know what part of the workpiece should be on thecentre If theworkpiece is a castingwemay have an outsidediameter or a hole that needs to run true in this case wewould put a dial test indicator onto the work and adjust thechuckalittleatatimeuntilthediameterrunstrueDonotturnthe chuck with the indicator in the hole Instead wind thecarriage forwards until the clock enters the hole and take areadingWind thecarriageback rotate thechuck90degreeswindthecarriageforwardandtakeanotherreadingAdjusttheworkinthechuckuntilitrunstrue

WhereacastingisstickingoutashereyoushouldtrytosupportthecastingwitharunningcentreThiswillhelptostopthecastingshiftinginthechuck

LatheCentreFinder

If there isnodiameterorholeyoumayhave tomarkout thecentreontheworkusingaheightgaugeandcentrepopitwithacentrepunchThenyoucanuseawobblerandatestindicatortosettheworktrueItwasoncepossibletogetalathecentrefinderconsistingof

a bar about 6in (150mm) long pointed at both ends with auniversaljointabout1in(25mm)fromthefrontendInusetheshortfrontendgoesinthecentrepopoftheworkinthechuckWhen you rotate the chuck by hand the pointed short endfollows the eccentricity of the centre hole which ismagnifiedaboutsixtimesatthetailstockendYouthenjusthavetoadjustthechuckuntilthetailstockendisrunningtrueatwhichpointthe centre in the work will also be running dead true I donrsquotknow anyone who makes these and second-hand ones areextremelyrare

Asimplehome-madecentrefinder

You can make a simple version of this that works well byusingamillingmachinepointedcentrefinderThisisaparallelbarwithaseparatemoveablepointedendThetwocomponentsare held together with a spring inside You need the pointededge finder a Morse taper parallel adaptor (the Morse tapershould fityour tailstock)aspringandashortstubofbar thatwillfitinsidethetaperedholderrsquosboretostopthespringgoingrightthroughPuttheshortstubofbarintothetaperinsertthespring follow up with the centre and put the Morse taperadaptorintothetailstockBringthetailstocktowardsthechuckuntil the centre of the centre finder is in the centre pop ThespringwillholditinplaceTousetheimprovisedcentrefinderput a dial test indicator onto the parallel part of the centrefinderrsquospointandrotatethechuckbyhandThepointwillrotateeccentricallyadjust thechuckuntil thecentre finderrsquospoint isrunningtrue

Usingascribingblockwithadialtestindicator

Move the tailstock along the bed until the point of thewobblerisinthecentrepopontheworkPutthetestindicatoronthefrontdiameterofthewobblerandadjustthechuckjawsuntilthewobblerisrunningtrueWhensettingupacastingorsomethingsimilarwherenotall

of the diameters are machined you should use the dial testindicator on diameters thatwill not bemachined such as theinsideofaflywheelrimWhenyouhaveturnedallthefinisheddiameters they should then be true with the unmachineddiametersSetting work in the four-jaw chuck depends on the

componenttobemachinedIfyouareusingroundmaterialyoucansetittoruntrueusingadialtestindicatorHoweverifyouaresettingaroughcastingthevariationofsizeandroughnessofthecastingsmaywellbeunsuitableforadialtestindicatorThere are alternativemethods of settingwork up in a four-

jawchuckespeciallyforcastingsOneofthesimplestmethodsis toholdasquarebar in the lathetoolholderandusethis tosetthejobtrueInuseyouwindthebaruptotheworkandsetthedial tozeroorotherwisemakeanoteofwhere it isWindthebaroutorawayfromtheworkTurnthechuck180degreesand wind the bar up against the work again You can

immediatelyseewhichwaythebarneedstomovesothatitisrunningtrueAdjustthecastinginthefour-jawchuckandmovethecastingtowardsthecentrepointRepeatuntilthecastingisrunning true This method is also useful if you are setting asquarebar to run true Justcheckeach faceof thesquarebarwiththebitofmetal

Settingacastingbyusingasquarebar

StickyPinMethod

An alternative the sticky pin method is especially suited tolocomotive wheels or flywheels An ordinary household pin ismounted in plasticine or Blu-tack perhaps stuck on the lathetool and is arranged to point to the inside diameter of thewheelor flywheel thearea that isnotmachinedbut is leftascastAdjustthecastinguntiltheunmachinedfaceisrunningastrueasyoucangetitandthewheelisreadytoturnThestickypinmethodisalsousefulforsettingupworkthathasachuckingspigot such as a locomotive smokebox door Just hold thechucking spigot in the four-jaw chuck and adjust the castinguntilitrunstrueontheoutsidediameterandthefrontface

Usingacommercialstickypintosetworktrue

Themethodsofcentringworkinthefour-jawchuckthathavebeen discussed are also suitable for setting work true on thefaceplate The next chapter looks at turning between centresandusingthefaceplate

6TurningbetweenCentresandFaceplateWork

Thischapterdealswithbasicturningbetweencentresandthenintroduces turning with the work mounted on the lathefaceplate

Headstockcentreanddriverplate(alsoknownasacatchplate)

TURNINGPLAINBARSBETWEENCENTRES

The most basic way of holding work for turning is between

centres Turning between centres is literally holding thecomponenttobemachinedbetweentwocentreseachofwhichhas a 60-degree included angle The headstock centre usuallygoes round with the headstockmandrel although some olderlatheshadanon-rotatingcentreandthedrivetotheworkwasbyapulleymountedontheworkThetailstockcentreisoftenafixedcentrethatdoesnotgoroundalthoughcentreswithballbearingscalledrunningcentresarereadilyavailable

Tailstockplaincentre

The component to be turned usually a shaft has a female60-degreecentreinbothendsthatisusedtosupporttheworkThe work can be turned round between centres so that bothends of the shaft can be machined Because the work ismountedbetweencentresbothendsoftheworkwillbetruetoeachother

Tailstockrunningcentreso-calledbecauseitrunsonballraces

CentringtheBar

FirstwehavetoputthecentresintoeachendofthebarIfthebarisshortsayuptoabout6inlongholdtheworkinthethree-jawchuckanduseacentredrillinthetailstockdrillchucktoputacentre intothebarAcentredrill isashortdrillwithasmallpilot on the end that has a 60-degree taper to the bodydiameterAbettermethodof centring thebar especially longbars is by using a three-jaw chuck and the fixed steady Thebarisheldinthethree-jawchuckwiththeotherendsupportedin the fixedsteadyand thecentre is formed in theendwithacentredrillAusefultoolthatcanbeusedtofindthecentreoftheshaftis

thecentresquarewhichisametalbladewithaVeeonitthatlocatesonthediameterofthebarMarkalineacrosstheendofthebarwitha scriber turn the centre square90degreesandthenscribeanotherlineWherethetwolinescrossisthecentreof thebar Tomake it easier to see the scribed linesblackenthe end of the bar with a permanent felt tip marker beforescribingCentrepunchthepointwherethetwolinescrossandput a 60-degree centre in each end of the bar using a centre

drill in a power drillHold thebar in a bench vicewhile doingthisPutacentredrillintothetailstockdrillchuckandinsertthebar in the three-jaw chuck Make sure the lathe is on a lowspeedabout300rpmwindthetailstockinandjustlightlycleanupthecentreholewiththecentredrilltotrueitupAnotherusefultooltofindthecentreofabarisabellcentre

punchThiscomprisesaconewithacentrepunchinthemiddleIn use place the bell end on the end of the bar and tap thecentrepunchwithahammertomarkthecentreTheendofthebar though needs to be reasonably square if using the bellpunchmethodThere are other similarmethods of centring bars but those

givenherewillbealltheturnerneedstolearn

Turningbetweencentres

Centringthebarusingthefixedsteady(Notethatthefrontclampisnormallydoneupwhileinuse)

Asimplecentresquare

Crosssectionofbellcentrepunch

MachiningtheBar

NowweneedtomountthebarbetweencentresThisissimplyamatterofputtingthebarbetweencentresandtighteningthetailstocksoitislightlypressingintothecentreintheendofthework To drive the work a carrier is fixed to the shaft andengagesapininacatchplatemountedonthelathemandrelAcatchplateissimplyablankdiscwithapinstickingouttodrivethecarrierthat isfittedtotheworkThecarrier isfittedtotheworkusinganAllenscreworboltTostopanymovementofthebarinrelationtothecatchplatethecarriercanbewiredtothecatchplatepinThiswill stop thecarrierand thework flappingaboutItisparticularlyimportanttostoptheworkfrommovingin relation to the catchplate when screwcutting betweencentres

Facingoffabarusingthehalfcentre

Nowthatthebarissafelymountedbetweencentreswecanstart turning it tosizeNormally the first thing todo is to facetheendsofthebartothefinishedlengthDecidewhichendofthebarhastheshallowercentreWewillmachinethisendfirstYouwillneedahalfcentreso-calledbecausealmosthalfofthecentre is missing This means the lathe tool can reach rightacrosstheendoftheworkwithouttouchingthehalfcentreWhenusinganyfixedcentreinthetailstockputabitofoilor

grease into the centre before use and top up as necessaryLightlywindthetailstockbarrelagainstthecentreandlockthebarrel so it canrsquotmoveSwitch the latheonandwind the toolacross to clean up the end Reverse the work and clean theotherendupat thesamesettingBothcentresshouldnowbethesamedepthMeasuretheoveralllengthofthebarTakethefinished length required from the overall measurement youhavejustmeasuredDividethisbytwoandthisishowmuchweneed to take off each end of the shaft so it finishes at therequiredlength

Askimmedbar

Ifyouhaveonechangethetailstockhalfcentretoarunningcentre if you donrsquot have a running centre change to a fixedcentreThehalfcentreshouldonlybeusedwhenfacingtheend

of the bar We will nowmachine the rest of the bar For thepurposeofthisexamplewewillassumethebarhasafinisheddiameter in themiddle with a step at each end First we willmachine the overall diameter to size To do this we need toskimthediameterandcheckthesizeTakeafinecutalongthebarusingthefinefeedifyouhaveoneMeasurebothendsofthebar Ifyouhavesetthelatheupcorrectly(seeChapter2)thebarshouldbeparallelIfitisnotadjustthetailstockbeforecontinuingAssumingthebarisparalleltakeanothercutortwosothatyouareabout01mmlargerthanthefinisheddiameterNowmove the tool in until almost at finished size and take alight cut about 10mm long along the bar Repeat this cut toensure the tool is notpushingoffMeasure thisdiameter youwill probablyhave towind the tailstockbarrel back toget themicrometerontotheendofthebarOnlymovethebarrelbackdo not slide the entire tailstock backMeasure the bar to findouthowmuchtoremovefromthediameterTakeanothershortcutandcheckforsizeWhenthebariscuttingtosizemachineall thewayalongYouwillprobablyhave to take twoor threecuts at the same setting until the bar ismachined to finishedsizeNowwewill turn the stepson theends Toensure that the

stepsare thecorrect lengthwewilluse thebedstopSet thebedstopthenwindthetopslidesothatthetoolisjusttouchingthe end of the bar For this exercise we will make the steps12mm long Wind the top slide along until the tool is justtouching the end of the turned bar Wind the top slide along119mmWecannowroughoutthestepateachendTurntheenddowntoabout02mmabovethefinisheddiameterYoucanusethefinefeedbutmakesureyouknockthefeedoffbeforethecarriagereachesthestopandfinishuptotheendbyhandRepeat for the other end Wind the top slide along theremaining01mmto12mmandfinisheachendinthesamewayasyoufinishedthemaindiameterDonrsquotforgettocleanupthefaceoftheshoulderyouhavejustturnedCongratulations you have just turned an accurate shaft

Donrsquotworryiftheshaftisatinybitundersizeyoucanprobably

makethematingholestofit

Thefinishedshaft

Usingachuckandarunningcentre

Usingthemethodsetoutaboveyoushouldnowbeabletoturn any shaft you require within the capacity of the lathe Avariationoftheabovemethodwheretheshaftissingle-endedistoholdoneendinthethree-orfour-jawchuckandsupporttheotherendwithacentreinthetailstock

Alargefaceplatesmalleronesareavailable

FACEPLATEWORK

Another basic way of holding work is on the faceplate Thismethod is used when the component is too large or isawkwardly shaped andwould be difficult to hold in a three-orfour-jaw chuck Usually the work is clamped directly onto thefaceplate often with a packing piece behind it to protect thefaceplateThefaceplateshouldbeflatandtruesothefirstthingtodo

whenyougetthelatheistocheckthefaceplatewithadialtestindicatorCarefullycleanthemandrelnoseandtheinternalholeinthefaceplateMakesurethemandrelcanturnfreelybyhandwith the lathe switched off and check that the face of thefaceplateisrunningtrueasclosetotheouteredgeasyoucanget If it is runningtrue runthetest indicatoracross the frontfaceofthefaceplatethisshouldbetrueaswellIfthefaceplateis running out itwill need to bemachined Put the lathe intobackgear if ithas it (topbackgearwillprobablybe fine)Youwill need a carbide-tipped tool ideallywith a small 45-degreechamferonthetipBringthetooluptothefaceplateand lockthe carriage Next you need to lightly face the faceplate right

acrossitsdiameterIfyouhaveapowercrossfeeditwillmakelight work of this but if not you can feed across by handFortunatelymost faceplateshavea series of rings on them toaid in setting up the work Machine the faceplate from theoutsidetothefirstringandstopforarest feedtothesecondring and so on until finished Depending upon how badly outyourfaceplateisyoumayhavetodothismorethanonceuntilit iscleanedupbutwhen it isdoneyouwill rarelyneedtodothisexerciseagain

Machiningaholeinablock

Asmentionedpreviously the ringsmachined on the faceplateareguidestohelpyousetuptheworkThiswilldoiftheworkisaroundcomponentbutweneedadifferentmethodiftheworkis square Take a block of metal for example that has beenmachinedalloverWewanttomachineaholeinit2infromoneedgeand1in fromanother edgeMarkout thepositionof theholeandcentrepunch it Put adeadcentre into the tailstockholdtheblockontothefaceplatebringthetailstockuptowardsthechuckandlockitWindthetailstockbarrelandcentreuptothe component and engage with the centre pop Lock thetailstock barrel Clamp the block to the faceplate using somepackingpiecesandfourclampsontheblockTheholeisnowoncentreandwecanmachineitinthecorrectplaceIf we need more than one hole placed accurately in the

componentwecanusetoolmakerrsquosbuttonstoensuretheholesare in the correct place Toolmakerrsquos buttons usually come insetsof fourOnebutton isusually longer than the rest soyoucanstillclockthediameterwhenitisclosetoanotherholeSetsare often available second-hand on eBaywhile they probablyhaveanobscureAmerican threadyoucanclamp themto theblock using your own BA or metric screws together with awasher

Settingupthefaceplateusingthetailstock

Asetoftoolmakerrsquosbuttons

Tofitthemtothecomponenttobeboredmarkoutdrillandtap holes in the approximate positions where the holes areneeded If you need a pair of parallel holes place thecomponentonasurfaceplate looselyfitthebuttonsandpushthem down onto a parallel or similar block of the correctthicknessandnipthescrewsupThespacershouldbesmallerthanrequiredbyhalfthediameterofabuttonIftheholesneedtobeacertaindistanceapartuseaspacer

of the correct size between the buttons (Remember tomake

thespacersmallerbyonediameterofthebutton)

Settingupacomponentusingtoolmakerrsquosbuttonstogetafixeddistancefromtheedgeofacomponent

TherearelotsofdifferentwaystosetthespacingofbuttonsItismainlyamatterofcommonsenseCastingsandflatcomponentscanbeboltedtothefaceplate

for machining A typical example of a flat component is aneccentric strap This type of component is usually made of acomponentthatiscutinhalfandboltedbacktogetherAholeisthenboredinitonthecentrelinetofittheeccentricThistypeofcomponentisoftendifficulttoholdinthelathechuckandisprone to distortion Castings are often too large to fit into alathechuckandso the faceplate iscalledon toundertake theworkAcastingcanoftenbebolteddirectlytothefaceplatetofacilitateeasymachining

Settingupacomponentusingtoolmakerrsquosbuttonstogetafixeddistancebetweenthecentresofacomponent

Work on the faceplate is often an odd shape or is set off

centreThiscauses it tobeunbalancedandasaconsequencethe lathemayvibratewhile thework is turningTocounteractthis tendency the faceplate should be counterbalanced byboltingweightsontoitAusefulsourceofweightsisthelathersquoschange wheels By bolting a change wheel or two onto thelightersideofthefaceplateyoucanbringthewholeassemblybackintobalanceAfterboltingthechangewheelsonspinthelathe by hand to check the balance The faceplate should notshowatendencytostopatoneparticularpointWhenyouarehappy that the faceplate is in balance the work and balanceweightsareboltedontightlyandsothattheworkdoesnotfoulthe lathewhen turnedbyhand switch themachine on in lowback gear to check for vibration Depending on what you areturning you should be able to run in top back gear or evenbottomdirectspeed

Asimpleclampsetisveryusefulwhenmachiningacastingonthefaceplate

TurningaFlywheel

Oneofthemainusesofafaceplateisturningalargediameteriron casting typically a flywheel or a locomotive wheel for asteamengineTheflywheelshouldbemountedsothattheinneredgeoftherimandtheouteredgeofthehubruntrueIfeitherofthemrunsoutitwouldbebetterthatthehubrunsoutasthe

rimwillbemorenoticeableonthefinishedengineClamp the flywheel down with some packing under the

spokessothatyoucanturnrightacrosstherimBecarefulthatyouclamptheflywheeltightenoughsothat itdoesnotmovebutnotsotightthatitdistortsRoughturn theoutsidediameterand facetherimusingthe

backgearUsingadirectdrivespeeddrillandborethecentrehole and either finish off with the boring tool or use a reamDonrsquot try reamingwithout boring the chances are that if youdotheholewillnotbetruewiththerimasthedrillprobablydidnotcutanaccurateholeDropdowntothetopbackgearspeedface the rim and turn the outside of the rim to the finisheddiameter Turn the flywheel over and finish the other face towidth

Astubarborsuitableforcentralizingalocomotivewheelorflywheel

TurningLocomotiveWheelFlanges

LocomotivewheelflangescanbeturnedonafaceplateYoucanpurchase blank end Morse taper arbors that fit into theheadstocktaperFitoneoftheseandturnaspigotonittotake

thewheel bore Thewheel bores should all be the same sizebut if they are different sizes machine the spigot to fit thelargestboremachinetheflangeonthatonethenmachinethespigotdowntofitthenextonemachinetheflangeandsoonIdeally the wheel bores should all be the same size but if

theyarenotproceedas followsSkimtheoutsidediameterofthe wheel flangemeasure and take it to the correct finishedsizeMovethelathetoolinbythedepthoftheflangeandturnthe tread Deal with all wheels like this machining all of theflangeoutsidediameterstothesamesizemovinginthecrossslidebythesameamounteachtimesothatallthetreadsendupthesamesize

UsingtheKeatsVeeangleplatetoturnaneccentriccomponent

KeatsVeeAnglePlate

TheKeatsVeeangleplate ismountedon the faceplateand isusedtoholdroundbarsquarebarandmiscellaneouscastingssuch as cylinders and steam chests The angle plate can bemountedanywhereonthefaceplateaslongasthelathecanbe

rotated safely and is in balance When spun by hand thefaceplateshouldnotshowatendencytostopatanyparticularplacewhenrununderpowerthelatheshouldnotvibrateAswellasholdingbarandcastingsforturningtheKeatsVee

angleplateisveryusefulformakingeccentriccomponentssuchastheeccentricsforasteamengineTo turn an eccentric use a test indicator to check that the

roundbarisrunningreasonablytrueWhenthisissatisfactoryyoucanturntheoutsidediameterofthebartofittheeccentricstrap (or component) including any step or groove requiredNextoffsettheKeatsVeeangleplatebytheamountyouwantthe eccentric lsquothrowrsquo to be Use the dial test indicator tomeasure the offset of the outside of the eccentric The offsetshouldbetwicethethrowYoucannowdrillboreandreamtheholeintheeccentricYounowhaveenoughbasic knowledge to carryout turning

between centres andwork accurately on the faceplate In thenext chapterwewill lookat holdingwork in a collet andonamandrel

7ColletsandMandrels

Thischapterexplainsallaboutholdingworkinacolletandhowyou canmake and use several different types of mandrel forworkholding

ERcollets

USINGCOLLETS

Quite a few different collet systems are to be found inworkshops Some are used for holding tools such as millingcutterssomeareusedforbarorworkpieceswhilesomemaybeusedwithbothbarandworkpiecesOne of the commonest is the ER collet which comes in

severaldifferent sizeseachhavingadifferent largediameterTheERcolletsystemallowsupto0039in(1mm)collapseofa

colletalthough in thesmaller sizesyoucanbuy thecollets in05mmincrementsA16mmcolletforexamplewillholdroundmaterialdownto15mmdiameterWhatevertheERcolletsizetheyallappear togodownto1mmminimumwhichwillclosedownto05mm

ERcolletadaptor

TherearemanytypesandsizesofERholderavailableAlltheusualMorse taper shank sizes are available and you can alsobuyvariousdiametersofextendedparallel shankholdersTheproblemwiththeseisthattheyaregreatforholdingtoolsthathave a short shank but because you need to use the holderwithadrawbaryoucanrsquotputlongbarstockrightthroughthemTo overcome this for lathe work you can also buy ER colletholdersdesignedtobefittedtoachuckbackplatethatyoucanmachine to suit your lathe so ensuring good concentricityBecause they donrsquot use a drawbar you can fit bar stock rightthroughandintotheheadstockmandrel

ERcolletadaptorfittedtoabackplateIalwaysleavebackplatesoversizesoIhavesomethingwithwhichtoclampthemdownwhenusedonamillordrill

When buying new and second-hand ER collets make surethey have the retaining groove near the nose end The older(andobsolete)EandEScollet typesdonothavetheretaininggrooveandarenotinter-changeableYouaremostlikelytofindEandEScolletsincludedwithasecond-handUnimatlatheDraw-in collets are usedwith a drawbar or collet tube The

drawbardrawsthecolletuptightbydrawingit intothelathersquosmandrelbyabar that runs through thecentreof themandreland screws into the centre of the collet Thismeans that youcannotputbarstockrightthroughthecolletToovercomethissome Morse taper collets use a hollow draw tube the collethaving an external thread tomatch the internal thread of thedrawtube

Draw-incollet

Special collets are made for the Myford ML7 Super 7 andML10 lathes These are Morse taper collets but rather thanhavingadrawbartheyareclosedwithanoseringthatfitsoveragrooveinthecolletThenoseringtightensthecolletintotheheadstockmandrelrsquos Morse taper It is extracted after use byundoing the nose piece which draws the collet out from theMorsetaperbythenosegrooveImperialandmetriccolletsareavailableuptofrac12in(12mm)diameterDead lengthcolletsareavailable that fit intoanattachment

usually fixed to the front of the lathersquosmandrel These colletsarecalleddeadlengthbecausetheydonotmovelongitudinallyunlike draw-in collets You are more likely to find collets likethesesecond-handratherthannew

BoxedsetofMyfordcollets

Deadlengthcollet

AvariationofthedeadlengthcolletistheCrawfordMultiborecolletThissystemhascolletsmadeofsegmentsheldtogetherbyspringsThecolletsareofvariablediameterandhavequitea

largeclosurerangeTheyaremorelikelytobefoundonalargercommercial lathe although you can get collets for smallermachinesWatchmakerrsquoscolletscanbeused inmost lathesbymaking

an adaptor for the headstock and a drawbar (or tube)Watchmakerrsquos collets are very accurate and can go down toverysmallsizesbuttheyhavelimiteduseinmostworkshopsYou can get a special watchmakerrsquos spindle for the EmcoUnimatlatheandthereisalsoaversionoftheCowellslathetheCW90thattakeswatchmakerrsquoscolletsFormost of thework carried out on the lathe youwill find

thatanERholder thatmountsontoachuckbackplate ismostuseful

Simpleexpandingmandrel

Simpleplainmandrel

MAKINGMANDRELS

There are several types of mandrel in common use inworkshops The most common is probably the expandingmandrelwhichcaneasilybemadeinanyworkshopInitsmostbasic form it is a bar turned to a size to fit the bore in theworkpieceItisthenthreadedwithataperedtapandslitat90degrees togive foursegmentswhichare thenexpandedbyascrewfittedintotheendofthemandrelAnother common mandrel is the tapered mandrel This is

usuallyalsquobetweencentresrsquomandrelandisoftenmadetotaperfromjustacoupleofthouovernominalsizetoacoupleofthouunder nominal size It is usually hardened and has a groundfinishTheworkpieceisheldinplacebybeingpushedontothemandreluntilitistightToremoveitjustpressitbackoutthewayitwentinWhereconcentricityisnotquitesoimportanttheworkpiece

canbeputonaplain turnedmandrelandtightenedupwithaboltandflatwasherExpandingmandrelsarealsomadecommerciallybutasyou

need a mandrel for each individual size of hole it can getexpensive if you need more than one or two different sizesCommercialmandrelscanbeobtainedwithMorsetapershanksto plug straight into the headstock Thismethod ensures thatthe mandrel should run dead true assuming both the Morsetapermandrel and theMorse taper in the headstock are bothcleanandfreefrommarksorswarfYou can also purchase Morse taper arbors with blank end

pieces from which to make your own mandrels First we willmake an expandingmandrel from a blank Morse taper arborYouwillneedtoturnthearbordowntofittheworkpieceboreIusually turn themandrelabout0010in (0025mm)oversize tostartwithandthenIdrillandtapthearborwithataperedtapThe drilled hole can go quite deep but the tapped hole onlyneedstogoinuntilthelockingbolt isabouthalfwaydownthelengthwheretheworkpiecewillsitPut the mandrel into the vice and cut along the mandrel

making four cuts around the circumferenceRetap thehole to

cleartheswarf fromthethreadandputthemandrelback intothe headstock taper Now you can lightly nip the screw up toexpandthemandrelslightlySkimthemandrel to finishedsizeuntil the workpiece will fit on without shake You can nowfurther tighten the screw so that the workpiece tightens ontothe mandrel When you slacken the screw the workpiece willcome off easily as you have skimmed it while it was slightlyexpandedYoucanmakeanexpandingmandrelfromabarheldin the three-or four-jawchuckorperhapsacollet inasimilarway Ifheld inachuck itmaynotgoback true ifyouneed touseitagainsoifpossibleyoushouldholdthearborinacolletFor aplainmandrel turn thediameter to fit theworkpiece

anddrillandtapforacapscreworaboltThereisnoneedtosplit this type ofmandrel You simply put the workpiece ontothemandrelandholditonwithaflatwasherAgainitdoesnotmatterwhetheryouuseabarinachuckorcolletorifyouusea Morse Taper blank arbor Arbors are very useful in theworkshop If youmake them fromMorse taper blanks or holdtheminacollettheycanbeusedoverandoveragain

8TaperTurningandLatheAccessories

Thischapterexplainshowyoucanturnataperusingatopslidetheuseoffixedandtravellingsteadiesandformtools

Turningataperwiththetopslide

TAPERTURNING

SometimesyouwillhavetoturnataperintheworkshopThatisa fairly easy jobWhat ismore difficult however is having toturnmatchingmaleandfemaletapers

Themethodyouaremostlikelytouseintheworkshopistoturn the two tapers with the top slide You should be able toturna taper longenough foraMorsetaperusingthismethodThemostimportantthingwhenturningtapersistoensurethatthe tool tip is at the exact centre height of the lathe This isbecause the taper will vary if the tool is not dead-on centreheightProbably the easiestmethod of turning aMorse taper is to

useadial test indicator toclocka lathecentreof therequiredMorse taper between centres The smaller end of the tapershouldbeatthetailstockendofthelatheThetopslideshouldbewoundalongthetaperby itshandwheelwhilethecarriageremainslockedThetopslideshouldbeadjustedangularlyuntilthedialtestindicatorreadszeroallthewayalongNowyoucanfinish turn the external Morse taper using an internal MorsetapersleeveasagaugetocheckthattheangleiscorrectTodothis make marks with a felt tipped pen along the taper andcheck that the test sleeve rubs evenly all the way along themaletaperAdjustifnecessaryuntilyouhaveaperfectfitToturnthematchingfemaletaperthelargeendofthetaper

willbeat the tailstockendand theboringbarwillbe invertedandcuttingon thebackof theholeDoing thismeans thataslongasbothofthetoolsareatcentreheightthetapersshouldmatchWecanusethemaletaperthathasjustbeenturnedasatestbarBoreoutthetaperverycarefullyyouwonrsquotneedtoremovemuchmaterial before the test taper goes too far intothe finishedbore Testwitha felt tippedpenuntil youhaveaperfectfitYou can turn any taper you need this way you are not

restrictedtoMorsetapersAnothermethodmostoftenusedforlongshallowtapersistouseataperturningattachmentTheseattachments are often available as extras on higher qualitylathes They comprise a slide mounted onto the back of thelathe Often the guide is dovetailed with a sliding blockattached to the cross slide to guide the tool on a taper ThedepthofcutisusuallyputonusingthetopslidesincethecrossslideisusuallydisconnectedfromthefeedscrewInthiswayit

isfreetomoveinandoutcontrolledbytheguide

Taperturningattachment

Settingthetopslidebyclockinganexistingtaper

Anothermethodweshalllookatfortaperturningistooffsetthe tailstock on its base This will make the work turnedbetween centres become tapered either large or small at thetailstockenddependingonwhichwaythe tailstock isoffset ifsettowardsthebackofthelathethediameterwillbelargerat

the tailstock end if the tailstock is moved to the front thetailstockendwill be smaller indiameter Theamountof taperthatcanbeturnedinthismannerislimitedsincetheheadstockandtailstockcentresareoutoflineThe final method of offsetting the workpiece is by using a

boringhead inthetailstockYouneedahome-madehardenedsolidcentrethatfitswheretheboringtoolwouldnormallygo(AsmallUnimatlathesizerunningcentremightbeideal)SettheboringheadsothetooltravelishorizontalYoucanthenoffsettheboringheadcentresocreatingataperThisisthesameassetting the tailstock over but you donrsquot have to realign thetailstockafterwards

Usingthefixedsteady

USINGFIXEDANDTRAVELLINGSTEADIES

The fixedsteady isusedmainly to turn theendofabaror tocentre a workpiece that is too large to fit through the chuckObviously bar stock should not protrude from the chuckmorethan is necessary to work on This is where the fixed steadycomesinThefixedsteadycanbesettothediameterofthebarsothattheendofthebarcanbemachinedsafely

Thesteadycanbesetusingachuckmountedonthistailstockadaptor

Travellingsteady

Settingthesteadybyusingachuckmountedonanadaptor

Onewaytosetthefixedsteadytosizeistoturnabitofbarin the chuck to the same size as the barwewant to use thesteadyonThenwecanmovethefixedsteadyalongthelathebedandfittheworkpieceintothechuckandinthesteadyTheendof thebar nearest to the tailstock shouldnowbe runningtrueandcanbeworkedonsafelyThebarcanbecentredrilledfacedorotherwiseworkedonAn alternative way to set the steady is to support the

tailstockendof thebarwitha threejawchuckmounted in thetailstockAdaptors to take the threejawchuckareavailableoryoucouldmakeyourownJustsupportthebaratbothendsinthethreejawchucksandsetthesteadyfingerstothebarThe fixed steadycanalsobeused to support tubes thatdo

nothaveanymaterialinthecentreThe fingers of the steady need to be lubricated regularly

while inuseThis iseasilydonebydrillinga smallhole in thetopfingerwithacountersinkinsidetheslottotakeoilThetravellingsteady ismostoftenusedwhenturningdown

small diameterbarsor screwcutting long slenderbars It boltsonto the front of the cross slide in line with the chuck and

travelsalongwhenthecrossslideismovedalongthelathebedWhen turning the travelling steady can either be set to thediameterofthebarbeforeturningandtoleadthetooloritcanbesettothefinisheddiameterrequiredandtofollowthetoolNormallythefingersaresetto leadtheturningtoolbut if thebarisroughforexampleifitisdentedorrustyitisbetterforthefingerstotrailtheturningtoolIfscrewcuttingthetravellingsteadyshould lead the toolso that itdoesnotdeflectorwearduetoaburrbeingthrownupbythescrewcuttingtoolSteadies will not be used very often but they are

indispensableontheoccasionswhentheyareneeded

Travellingsteadywithleadingfingers

Travellingsteadywithtrailingfingers

MAKINGASIMPLEFORMTOOL

Youmay often need to produce a particular shape such as aradiusonacomponentTheeasiestmethodtodothisiswithaformtoolAsanexamplewewillmakeasimpleformtooltocutahalfcircleonabarofbrassForaradiusof3mmforexampleweneedtoproducea formtoolusinga6mmdiameterdrillorreamFormaterialwewillusegaugeplateahighcarbonsteelthatcomesintheformofagroundflatbarApieceabout5mmthick and10mmwide is needed although the size is not thatimportantaslongasthegaugeplateisthickenoughtoabsorbanyturningstressesIdeallyweneedataperedreamerthatwillproduce a 6mm diameter hole somewhere along its lengthalthough you could use a parallel 6mm reamer a slot drill orendmillorevenastandardtwistdrillDrill a hole through the gauge plate and open up to 6mm

diameterAim togetagoodsurface finishon thesidesof thehole Hacksaw and file half the hole away to leave the shaperequired on the finish turned component Now we need to

harden the tool although ifweare justdoingacomponentortwoinbrasswecouldprobablygetawaywithouthardeningitHardeningissimpleenoughheattheworkingendofthetool

toredstopheatingandletthegaugeplaterestforacoupleofminutesThiswillgive thegaugeplateachance tochange itsinternalstructureReheattoredandquenchinatubofwaterThisshouldhardenthetoolAlthoughabitbrittle itshouldbefine for making a few components Stone the top of the tooluntil thecuttingedge issharp Ifnecessaryyoucanpolishtheinside of the radius that is going to do the cutting There areseveralmethodsyoucanuse includingapieceofwetanddrypaperaroundabitofbaraverysmallgrindingwheelcalledamounted point or a bit of round bar with fine valve grindingcompoundonitWhicheveryouuseaimforapolishedfinishasthe finish on the turned component is directly related to thefinish on the form tool You canmakeall sorts of simple formtools with gauge plate a typical example being a facing toolwitha30-degreechamfertofaceandchamfernuts

CopytemplatereadytouseMetal

MachiningfromaTemplate

MachiningfromaTemplate

YoucanmachineaprofilefromasimpletemplateThetemplatecanbecutfromgaugeplatewithafileormachinedbutitdoesnot need to be hardened The template could be used tomachinea large radius suchasa smokeboxdoor Inuse thetemplateismountedonablockonthelathebedandthecrossslide is kept in contact with the template by being pushedagainstthetemplatewithaballracefixedtothecrossslideInthenextchapterwewillbelookingatdrillingandreaming

9DrillingandReaming

ThischapterexplainshowtousedrillsandreamersinthelatheTherearemanydifferenttypesofdrillsandreamersTheyareessentialtomakingcomponentsinthelatheWewilllookatthevarioustypesandhowtochoosethespeedsandfeedsforusingthem

Thisdrillchuckrequiresachuckkey

TYPESOFDRILL

Drills are normally held either in the tailstock if they have aMorsetaperor inadrillchuckiftheyhaveaparallelshankA

drillchuckismountedonaMorsetapershankthatisusuallythelargestMorsetaperthatthetailstockwilltakeThelargestsizeof drill that will normally fit a drill chuck is frac12in (13mm) indiameter although larger chucks are available at a cost Thesmallest sizeofdrill thatafrac12in (13mm)drill chuckwill take isusually about 116in (15mm) This is because the larger drillchuck is incapableofclosingdownenoughto take thesmallersizesofdrillThismeanswewillprobablyneedtwodrillchucksoneforlargerdrillsandoneforsmallerdrills

Hand-tighteningdrillchuck

TherearetwomaintypesofdrillchuckOneistightenedbyusinga chuckkeywhichhasa small bevelgearbuilt on to itthatmates with the outer sleeve of the drill chuck itself Theother type is hand tightenedwhere the outer chuck sleeve isknurledtotightenthedrillthesleeveisturnedbyhandLargerdrillsabovefrac12in(13mm)usuallyhaveaNo1orNo2

MorsetapershankYoucangetMorsetapersleevestoconvertalargeMorsetoasmallerMorsetaperYoucanalsogetasmallMorsetolargeMorsetaperconverteraswell

Drillwithataperedshank

Some larger drills are also available with parallel shanksTheyaremadewithasteppeddownfrac12inparallelshankandarecalledblacksmithrsquosdrills

Blacksmithrsquosdrill

Themostusefuldrills in theworkshopcomeassetsofhighspeedsteeljobberdrillsinacaseThemostpopularsetcovers1mmto6mm increasingby01mmstepsAnotheruseful setcoversfrom6mmto10mmalsoincreasingby01mmstepsIfyouareintomodelengineeringasetofnumberdrillsfromNo1toNo60istoberecommended

Asetofmetricdrillscovering1ndash6mm

Drills are also available in different lengths Stub drills areshorter than standard jobber drills Several lengths of longseries drills are also available ranging from one and a halftimesthelengthofajobberdrilluptoseveraltimesthelength

Differentlengthsofdrills

Mostdrillshavetwoflutesbutcoredrillsarealsotobehadwith three four or evenmore flutes As their name suggeststhese are usually used for drilling out cored holes in castings

CoredrillsarenotnormallycapableofstartinganewholebutareusedforopeningupexistingholesAstandarddrillusuallyhasanincludedangleof118degrees

Stub drills and cobalt drills often have a 135 to 140 degreeangle for use on hardermaterials such as stainless steel andaircraftsteelsBack rakeondrills is oftenground radially Another typeof

pointhoweverhasfourfacetstothepointFour-facetdrillsaremuch better at starting a hole than a standard jobber drillwhich tends towanderunless followingacentrepoporcentredrill Four-facet drills also require less pressure to drill a holesincethepointisthinnerthanastandarddrillandtheyarefareasier to sharpen accurately by hand than standard jobberdrillsDormerdoarangeoffour-facetdrillscalledA002withatitaniumnitridecoating(TiN)andafour-facetpoint

Three-flutecoredrill

DormerA002four-facetdrillpoint

To drill an accurate sized hole requires two ormore stepsfirst youdrill the hole undersize (by perhapsfrac12mm) then youfollowthroughwithasizedrillThechancesaretheseconddrillwillcutdeadtosizeasitisonlycuttingasmallamountfromthediameter Obviously if you are drilling a large hole moreintermediatestepsmayberequiredSpeedsfordrillingarethesameasthosegivenforturninginthetableinChapter3

Setofcentredrills

REAMERS

There are several types of reamers available for use inworkshops again with either Morse taper or parallel shanksSomehavesizeparallelshankstheshankbeingthesamesizeas the reamer while others are availablewith shanks smallerthanthereamedsizeThereisalsothewaistedreamerwheretheshankisthesamesizeasthereamerthemiddleissmaller(waisted)andthecuttingendistheholesizeYoucanalsogetadjustablereamerswheretheendisexpandedbytheuseofascrewinthecuttingendofthereamer

Handreamerthefrontparthasaslighttaper

Straightshankmachinereamer

Waistedshankmachinereamer

Morsetapershankmachinereamer

Parallelreamersaredividedintotwotypesparallelmachinereamerswhere thecuttingdiameter is thesameallalong theream and hand reamers where the cutting end is slightlysmallerandtapersuptothefulldiameterWhen drilling a hole for reaming it is advisable to use the

two-holemethodfordrillingYouaremore likelytogetagoodsize hole prior to reaming For small reamers up to 04in(10mm) leave about 0012in (03mm) for the reamer toremoveForreamersuptofrac34in(19mm)leave0016in(04mm)and over frac12in (13mm) leave 0020in (05mm) For reamingspeedsuseabouta third toahalfof thedrillingspeed for thesamediameterFeedsshouldbefrom0002to0004in(0025ndash005mm)per toothper revMultiply the feedper toothby thenumberofteethtogivethefeedperrevolutionItisbesttouseneatcuttingoilformostmaterialsexceptfor

aluminiumforwhichparaffinshouldbeusedandplasticwhichrequirescompressedairorplainwaterYoushouldnotuseoilasacuttinglubricantforanytypeofplasticasitcanattackandordegradetheplastic

10BoringToolsandBoringHeads

Thischaptershowsyouhowtoboreholesinthelathewiththeworkheldinachuckmountedonthefaceplateorfixedtothelathecrossslide

TypicalHSSboringbar

DIFFERENTTYPESOFBORINGBARS

BoringaholetosizeisoneofthemostexactingjobsyoucandoinalatheItisrelativelyeasytoturnashafttofitaholebutitis much harder to bore an accurate hole to fit a shaft Ifpossibleyoushouldboretheholebeforeturningtheshaft

YouarelikelytocomeacrossHSSboringbarsorinsertedtipboringbarsBothhavetheirusesTheHSStoolisidealformostgeneralhole-boringjobsbuttheinsertedtiptoolisfarsuperiorfor materials such as cast iron The boring bar should be aslargeasyoucangetintotheholewhilestillallowingswarftoberemovedTheboringbarshouldonlyprotrudefarenoughtoenableitto

go completely through the bore Any more protrusion than isnecessarymay result in chatter or a dig in in the bore Thefront clearance on the boring bar tip should be as small aspossiblewithoutrubbingasstrengthisimportantBoringcanbeusedtofinishaholetosizeorsimplytotruea

holeupafterdrillingandpriortoreaming It isbesttoruntheboringtoolthroughtheholeusingafinefeedtothecarriageifyouhave the feedoptiononyour latheThe final finishingcutshouldbeputthroughtwoorthreetimesatthesamesettingtoeliminateanyspringinthetoolworkorlatheIftheholehasanintermittentcutthroughitsuchasacrossholetheholeisbestboredtosizeIt ispossible toborequite smallholes if youhave the right

tool Commercial lsquosmall holersquo boring tools are very expensivebut Ibuythemsecond-handwhenever Iseethemso Iusuallyhave a stock It is easy if time consuming to grind up smallboringbarsbuttheyareveryusefulespeciallywhenyouneedtotrueupasmallholepriortotappingorreamingEndmillsandslotdrillsmakeusefulboringtoolsAs longas

yougetthecuttingedgeoncentreheighttheywillboreaswellasaproperboringbarespeciallyinaluminiumYoucanmakesimplehome-madeboringtoolsbydrillingand

reamingaholetotakeaHSStoolbitintoasteelshankIdeallythe shank should be made of high tensile material or silversteelThetoolbitshouldbesecuredwithahightensilesocket-headedgrub screwor similar The tool bit caneitherprotrudefromthesideoftheboringbarforthroughholesorprotrudeatthe frontof theshankat45degrees ifyouareboringablindholeRoundboringbarscaneitherbeclampedintotheVeegroove

foundinsometoolholdersorheldinasplitsquareshankEithermethodissuitableespeciallyastheshankcanbeslidinoroutofthetoolholdertominimizeprotrusionSpeciallyshapedtoolbitscanbeusedtoundercuttheendof

the borewhen it needs to be screwcut and canrsquot be cut rightthrough Inserted HSS boring bars can also be ground up forundercuttingbeforescrewcuttingThereareseveralmethodsofcheckingaboreforaccuracyIf

youhavetoboretheholetofitanexistingcomponentperhapsaballraceyoucanuse theexistingcomponentasagaugeorturnupagaugeRoughout theborewithina few thouof thefinishedsize taking twoor threespringcutsUsea telescopicgaugeapairofcalliperswithamicrometeroradigitalverniertomeasuretheholeBorethestartoftheholebynomorethanonethouata timedonotgoright throughtheboreTest thefrontoftheboreifthegaugedoesnotgointotheborerunthetool right throughunderpower feedBoreout the frontof theholebyanotherthouchecktheboreandrepeatuntilthegaugejustgoesintothestartoftheholeFinishtheboreatthesamesetting checking that the gauge just enters Take a couple ofspringcutstoensuretheboreisparallelYoushouldnowhaveanaccuratelysizedholeThe trick to boring is to finish with very fine cuts Many

engineersdonotrecommendfinecutsbutIhaveneverhadaproblemaslongasthetoolissharp

Asetoftelescopicgaugesforcheckingaboreusedinconjunctionwithamicrometer

Checkingaborewithahome-madegaugeTheleadinisonethousmallerthantheborerequired

USINGABORINGHEADINTHELATHE

AnothermethodofboringacomponentinthelatheistoboltitdowntothecrossslideWhentheworkpieceisbolteddownandtheholeposition is linedupwith theheadstock youcanboretheholeintheworkpieceinseveralwaysFirst however you might need to put a hole into the

workpiece to clear the centre of the hole out of theway Youcandothisbyusingadrillinathree-orfour-jawchuck(smallerdrillscouldbeusedinadrillchuck)Startwithasmalldrillandworkupalmosttothefinishedsizeoftheholetobebored

Boringaholereadyforreaming

Toboretheholethefirstoptionistoholdaboringbarinthethree-jaw chuck This is a good basic method of boring aworkpieceonthecrossslideTheonlyawkwardbitisadjustingtheboringbarsothatasizeholeisboredThisisusuallydonebyanadjustingscrewpressingontothebackofthetipoppositethe cutting edge The tip itself is usually clamped by a grubscrewthroughthesideoftheboringbarHoweveryoucanuseaboringbarthatisafewthouundertherequiredsizeandfinishoffwithareamerA similar way that is easier to adjust is to use the same

boringbar in the independent four-jawchuckThen insteadofadjusting the tip in the boring bar you can adjust the entireboringbar inthefour-jawchuckThisasyoucanimaginewillbealoteasierthantryingtoadjustthetipintheboringbarThethirdmethodofboringworkonthecrossslideistousea

properboringheadThis iseasy toadjustas it isdesigned forthisverypurposeFinallyyoucouldusea lsquobetweencentresrsquoboringbarwhich

isheldbetweentheheadstockandtailstockcentresThisistheonly option when you are doing a long bore such as a largecylindercastingforalocomotiveortractionengine

Boringtheholeusingthefour-jawchuckmethod

Usingtheboringheadinthelathemandrel

Unlike when you are facing and boring a component in achuck you will not be able to face across the front of thecomponent (Boring heads with the ability to face across theworkareavailablebutareunlikelytobefoundintheamateurrsquosworkshop) Thismeans you will have to face across the workwith a flycutter in order to keep the face true with the boreFlycutters are available quite cheaply or you couldmake yourownandholditinthefour-jawchuck

Aflycuttersuitableforfacingthefrontofacomponentthathaspreviouslybeenboredonthe

crossslide

11KnurlingRadiusTurningandProductionMethods

This chapter explains how to use knurling tools and radiusturningtoolsaswellasusingbasicproductionmethods

KNURLING

Knurlingistheprocessofformingorimpressingapatternonapiece of metal often for the purpose of making a grip for apieceofequipmentsuchasaknobBothstraightanddiamondknurlscanbeproduceddependingonthetypeofknurlyouareusing Diamond knurling is usually done with two knurlingwheelsalthoughsingle-wheeldiamondknurlsareavailableKnurls are also available in fine medium and coarse sizes

although the size is relative fromdifferentmakers The speedfor knurling is usually about half of the turning speed for thesame diameter bar Normal knurling is of the male patternwheretheknurlingconsistsofraisedpyramidsFemaleknurlingismuchrarerandconsistsofdepressedpyramidsThere are threemain types of knurling tool but only two of

these are found in the average workshop The first type ofknurling tool is the so-called lsquocutrsquo knurling toolwhichactuallycutsaknurlratherthanpressestheknurlintotheworkThisisaspecialized tool more often used in industry and is veryexpensivesoitisnotfoundinmanyhomeworkshops

lsquoBumprsquoKnurling

The most common knurl is the single-or double-wheel knurlsometimes called a lsquobumprsquo knurling tool The wheels aremountedat the frontof the tool This typeof knurl is pressedintotheworkbyusingthecrossslideandcanproduceagoodqualityknurlHowever itdoesputveryheavypressureonthemandrelandlathebearings

Acommerciallyavailablestraddleknurlingtool

StraddleKnurling

Thebest typeofknurl foroccasionaluse is thestraddleknurlwhich has two knurling wheels that completely straddle theworkpieceThistypeofknurldoesnotputastrainonthelathebearings and so is preferred bymost lathe users (Two-wheelknurlingtoolsareavailablethatresemblestraddleknurlingtoolsbut they donrsquot open up to take anything more than smalldiameters relying on pressure at the side of the job like alsquobumprsquoknurl)To set the straddle knurl up wind the tool against a bit of

plateheldontothesideofthebarRemovetheplateandmovethetoolinbythethicknessoftheplatehalftheknurldiameterandhalfthebardiameterThiswillputthetoolontothecentrelineofthebar

Settingtheknurlingtool

In use set the knurling wheels to the centre as describedabove wind the knurls onto the outside diameter of the barwindtheknurlawayfromthebarandmovetheknurlingwheelsclosertogetherbytwicethedepthoftheknurlpatternSwitchthelatheonandwindthetoolbackontothecentrelineandthetool should start to form the knurl You can now traverse theknurlingtoolalongtheworkpieceto formtheknurl remembertousecuttingoilNote that theknurlsshouldhavechamferedsidesifyouaretraversingalongtheworkpieceYouneedtogodeepenoughsotheknurlisfullyformedbut

notsodeepastodeformtheknurlBecausetheknurlstraddlestheworktheknurlsstartoff independentlyandmaynotbe inalignment around the diameter Once you start moving theknurlingtoolbackwardsandforwardsalongtheworkhoweverthetoolshouldlineitselfupThismeansyoumayhavetoturndownorpartoffthebarwhereyoustartedtheknurlIfyougotoodeepespeciallyinaluminiumthewholedepth

ofknurlcouldgetdestroyedandevendropoff theparentbarThis is called flakingKnurling isnotadifficultprocessa littlepracticewillsoonhaveyouknurlinglikeaprofessionalengineer

Anaccomplishedbitofknurling

AformtoolcuttingaballTheinsetviewshowstheformtoolandafinishedball

RADIUSTURNING

Sometimesweneedtoformanexternalradiusontheendofabit of bar perhaps for a ball-shaped handle We can use asimple lathe attachment to do this Basically the attachment

consists of a short turning tool mounted onto a U-shapedcomponent that is arranged to pivot on another U-shapedcomponentheldinthelathetoolpostBy pivoting the attachment back and forth a radiuswill be

generatedForatrueradiusthepivotpointshouldbesetonthecentrelineofthebarTheradiusgeneratedwilldependonhowfarthetoolbitissetbackfromthecentrelineoftheworkpieceTosetthetoolupwindtheattachmentuptoaplateheldto

the sideof thebar youareworkingon remove theplate andwindinthewidthoftheplatehalfthewidthofthebarandthewidthofthefixturetothecentrelineofthepinThiswillputthepivotonthecentrelineThenyoucansetthetooltotheoutsidediameterofthebarThiswillproduceaballthesamediameterasthebarTo turnan internaldiameteruse the samemethodbut the

turning tool will need to pass through the centre of the pivotand out the other side You will be limited to shallowdepressionsratherthanlargesemicirclesbutthistechniquecanstillbeusefulonoccasionThealternativemethodof formingaball iswithaball form

tool

Astopbarblockforthecarriagestop

PRODUCTIONMETHODS

PRODUCTIONMETHODS

Foreaseofproductionthefirstthingyouneedtouseisabedstop (see Chapter 5) The chances are that you will need tomakeyourownTheoneIuseisveryversatileandconsistsofablockmountedatthefrontofthelatheheadstocktogetherwitharodtoactasthestopDependinguponwhatyouaredoingitmaybeusefultohave

morethanonestopbareachwithitsownseparatestopblockInusethebarisinsertedintothemainblockasfarasthestopblock(if fitted)andlockedinplaceThefirststopbarcouldbeusedto facetheworkpieceandthesecond(shorterbar)couldbe used to turn along the diameter while a third bar couldpositionthepartingofftoolAnalternativeadditiontothestopbarcouldbeawasher(orwashers)ofknownthicknessplacingthewasher(orwashers)onthebarwillextendthestoppositionbythethicknessofthewashersusedAusefultipistostampanumberonthestopblockssothat

eachone isnumberedYoucouldalso stamp the thicknessonthewasherssoyoudonrsquothavetokeepmeasuringthemandjustpickthemupinthecorrectorderItsavesalittletimeandhelpsavoiderrorsThe whole point about using a stop is the consistency of

positionwhichistransferredtotheaccuracyofthecomponentit gives Once you have learnt to use a stop youwill wonderhowyoumanagedwithoutitEvenforone-offcomponentsitwillsaveyoutimeForatypicalone-offsteppedshaftsetthestopsotheturning

tooljustfacesthebarandfaceoffMove the top slide along for the length of the turned step

requiredTurnthestepYounowhaveastepontheendofthebarofaknownlengthNofiddlingnomeasuringndashyouknowitiscorrectUsing the bed stop offers a simple way of doing repeat

turning of lengths and diameters in the lathe Stops are notlimited to production methods they are very useful formachiningone-offsaswell

A single stop bar will serve for much of the work you aredoingbutsometimesyouneedmorethanonestopTheanswerhereistousemorethanonestopbarinconjunctionwithastopblockEachbarhasitsownstopblockthatcanbetightenedupThenyoucaninterchangethestopbarsandeachbarcanbesettotherequiredlengthbyusingavernierorruleYoujustsetthetwostopblockstothedifferencerequiredandlockthestopbarintheholderasnormalWhenyouneedmorethanoneofeachitemitisveryeasyto

save time in theworkshop once the lathe is set up you canmake several items in quick succession A typical example ofthis type of production is a simple spacer Set a facing andchamferingtoolinonetoolholderapartingofftoolinanothertoolholderandadrillinthetailstockchuckThefacingtoolandparting off tool are in fixed positions to each other so it is asimplematter of drilling thehole facingoffwithone tool andparting off with the other As long as the gap between thepartingofftoolandthefacingtoolremainsconstantthespacerswill remain at the samewidth each time youmachine one ofthemTheeasywaytosetthethicknessofthewasheristofaceoff

theendofthebarbringthepartingofftooluptothefinishedface and lock the cross slide Wind the parting off tool backslightly so you can move the bar forward in the chuckMeasuring with the vernier calliperrsquos depth rod from therighthandfaceofthepartingofftoolbringthebaroutslightlylonger than is needed for the washer thickness Using thetailstock chuck drill the hole using a centre drill for the firstwashertoensurethedrill runstrueNowsetthefacingtool inpositionfaceoffthewasherandpartofffromthebarMeasurethe washer and adjust the facing tool either way so that thethicknessof thewasher iscorrectPull thebar fromthechuckslightlyfurtherthanthefacingtoolsothateachwashercanbefaced to lengthYoucanmakeasmanywashersasyouneedall of the same thickness The same applies to nuts and anyothercomponentthatneedstobeasetlengthIfmakingboltsor screws theprinciple is thesamebutyou

willneed to turndown thediameter tobe threadedThis timethedifferencebetweenthepartingofftoolandtheturningtoolisthethicknessoftheheadInordertofacetolengthhoweverawasher of a known sizemust be inserted between the stopblockandthecrossslideThiswasherwillbethelengthoftheturneddownportionofthecomponentIfyouwanttomakeabatchofcomponentsbutdonrsquotwantto

keepmovingorchangingtoolsyoucanmachinethebatchonestepata timedoingoneoperationoneachcomponentbeforedoing the next operation on all the components Repeat thisuntil the complete batch ends up as completed componentsYou have the added advantage that the components willprobablyallbethesameshapeandsizesomethingthatisnotalwayspossiblewhenmachiningeachcomponentindividuallyTo make a batch of components such as washers to the

samethicknessisquitesimpleSetupapartingtooltopartoffthe components and set up a facing tool to face thecomponentsThedifferenceinpositionbetweenthefacingtooland the parting toolwill be the thickness of thewashers Youcanadjustthethicknessofthewasherbymovingthefacingtoolbackwardsor forwardswith the topslide toadjust it The rearpartingofftooldoesnotmoveotherthantopartoffthewasher

Makingwasherstothesamelengthusingfixedpositiontools

TAILSTOCKTURRET

AnotherusefulaccessoryisthetailstockturretThisisarotatingheadthatisusuallysetbackatanangleItfitsintothetailstockof the lathe and has multiple stations to take different toolsoftenitwilltakefourfiveorsixtoolsThebenefitofthisisthatitcanhaveabarendstopacentredrilladrillacountersinkatapandadieoranycombinationthereofallsetupreadytousein sequence The tools normally fit into holes bored into theturretToavoidtoolsstickingouttoofar it isbesttousestubdrillsinsertedintoroundbarsthatfitintotheturret

Anindexingturretthatfitsdirectlyintothetailstockofthelathe

YoucaneitherdrillandtaptheroundbarsoruseLoctite tosecure the drill in the round bar You can also buy roundadaptorswithaJacobschucktapermachinedontheendtotakechucksAnothermethodoffittingchucksistodrillandtaptheround bar to take chucks with threaded extensions ThesechuckscanoftenberetrievedfrombrokenBlackampDeckertypedrillsDieholderscanslideonapieceofroundrodintheturretFor

smaller diameter threads you can stop the die from rotatingusing your hand There is no need to reverse the lathe whenthreading just stop it and spin the die off by hand the samegoes for taps For larger taps and dies you can use a shorttommybartostoprotationbutmakesurethatthetommybarpositionisclosertotheworkthantheendofanyofthedrillsorthetommybarwillsnapthedrillsifyouletgoofitorifthetapordiejamsupYoucanalsomakeorbuyarunningcentretofitintotheturrettosaveremovingitwhenyouneedtousealathecentreOnlydothiswithsmallorlightworknotheavybarsorfor largecutsWhenused inconjunctionwithagoodbedstop

system a tailstock turret becomes a very versatile productionfacilityTheturretcanbemademoreversatilebyfittingalever-feed

tailstockattachmentoracapstan-style feedattachmenttothetailstockturretEitheroftheseattachmentswillmaketheturretveryfastinoperation

Anindexingturretsetupwithastopandacentredrill

Standardlever-feedtailstock

SECONDOPERATIONWORK

SECONDOPERATIONWORK

Sometimes it is necessary to do second operation work on apart-machinedcomponentUsually thiswillbeon theoppositeend to the one already turned There are two main ways ofholding theworkpiece in the correct position for furtherworkthechuckbackstopandsoftchuckjawsThechuckbackstopisquitesimpletomakeItconsistsofa

draw-incolletapieceofplainbarforthestopabitofthreadedbar a nut and a top hat collar The collet goes into the lathemandrelandisdrawninbythethreadedbarThethreadedbargoesthroughthemandrelandislockedinplacebythenutandthe tophatcollarat the left-handendThe tophatcollar is toprotecttheendofthemandrelThestopbarfitsthecolletandispositionedsothattheworkislocatedattherightdepthinthechuckThismeansthateachcomponentput intothechuckupagainstthebackstopwillalwaysbeheldinthesameposition

Capstan-stylelever-feedtailstock

Adraw-inbackstop

Softjawswithhexagonsadded

The secondmethod is to hold the component in soft jawswhich are bored out to hold the component (see Chapter 5)ThismeansthecomponentshouldrundeadtrueandeachonewillbeheldinthesamepositionreadytobemachinedSoft jaws tend to be used for larger components while the

backstop ismore likely tobeused forbarworkYoucanboltextension pieces to soft jaws to hold larger diameters orextensions can be machined to make a nest to take largercomponentsWhensoft jawsarewornoutandfaceddowntoo

lowforfurtheruseyoucanboltapieceofhexagonbartoeachjawtogivethemanewleaseoflifeIfyouhaveabatchofthreadedcomponentstofinishonthe

second end you can screw them into a bit of bar held in thechuck If theyarehexagonbolts just tightenup lightlywithaspanneriftheyareroundheadandtheheadwillbemachinedlateryoucouldtightenanduntightenthemwithapairofpliersThe more production work you do the more varied the

methods you will learn and the quicker you will makecomponentstoahighstandardofaccuracyA sensitive drilling attachment can be very useful when

drillingwith tiny drills The feed is by hand which gives it itssensitivity The attachment can also be used for small tapswherethetravelisfairlyshort

Machiningscrewheadsbyholdingthescrewinathreadedmandrel

Asensitivedrillingattachmentthatfitsintothe

tailstockchuck

ThisVeeattachmentisusedforcrossdrillingandcanbeusedintheheadstockorthetailstockofthelathedependingonthelengthofthebartobecrossdrilled

ThisisarevolvingtaperforthetailstockIfyoufitadrillchucktoityoucanuseitasarunningsupportforsmallbarwhereacentreisnotpermissible

12TapsDiesandScrewcutting

Thischaptershowshowtousetapsanddiestocutinternalandexternal threads in the lathe Italsoexplainshowyoucansetupasimplegeartrainandcutascrewthreadwiththehelpofascrewcuttingdialindicator

Atypicaldie

CUTTINGTHREADS

Threadcuttingeither internalorexternal isan importantpartoflearningtousealatheThepurposeofathreadisusuallysothatyouareabletoholdpartstogetheralthoughotherusesforthreadssuchasleadscrewsandfeedscrewsformachinetoolsareoftencalledfor

Safetyhasalreadybeencoveredindepth(seeChapter2)butafewextrawordsonsafetywhenthreadcuttingarecalledforWhen tapping a hole or threading a bar from the tailstock atailstocktapordieholderisoftenusedForthesmallerthreadstheholdershaveaknurledbodyandrotationcanbestoppedbysimplyholdingthebodyoftheholderinyourhandAslongasyoukeepyourhandawayfromthechuckandany

sharp lathe tools on the cross slide you should be fine (ifpossible remove either the tool holder or the tool itself )Providedthereisnothingtocatchorsquashyourhandonyoucan hold the knurled tap or die holder in your handwhile thelathe is running slowly under power and releasing the holderwhen the full length of the thread is cut or the pressurebecomes too great for you to stop the rotation (By slowly Imeaninveryslowbackgear)For largerthreadshoweveratommybarwilloftenneedto

beusedtostopthetapordieholderfromrotatingWhenusingthe tommy bar to prevent rotation do not under anycircumstances use the lathe under power Instead switch themachinerightoffandunplugit ifpossibleTurnthetapordieholdingthetommybarwiththerighthandandstopthechuckfromrotatingwiththelefthandThere are already many published charts providing thread

data covering such factors as tapping hole sizes minimummaximum and effective diameters as well as pitches andthreadsperinchIwillnotbeprovidingthemherebutwishtopoint out that tapping size drills can vary with the materialbeingcutWhenIamtappingsmallsizes instainlesssteel forexampleIusuallydrillthehole0004in(01mm)largerthanthefigurestated in thechartThisway Iam less likely tobreakatapinthehole

HSSorCarbonSteel

TapsanddiesareusuallymadefromcarbonsteelorHSSHSStapsanddiestendtoremainsharpformuchlongerthancarbonsteeltapsbutcarbonsteelisusuallycheaperNewcarbonsteel

tapsanddieswillprobablybefineforsmallerholesandsoftermaterials but wherever possible HSS should be your firstchoice Second-hand taps and dies are sometimes availablefromtoolshopsoroneBaybutinmyexperiencetheyareoftenbluntandnotworthbotheringwith

Lubricants

Whether tapping threading with a die or screwcutting it isnormallyessentialtousealubricantevenonbrassForbrassaluminium and bronze kerosene (paraffin) or white spirit isgenerallyusedandcanwithadvantagehaveasmallamountofcuttingoiladdedFor steel and stainless steel amodernpaste-based tapping

compound or cutting oil should be used This can also beappliedtocopperthismetalcanbestickybuttakeiteasyandall should gowell I also use paste or cutting oil on cast ironAlthoughmostrecommendationsaretocutcastirondryIhavefoundalubricanttobeveryhelpful

Screwthreadpitchgauge

ThreadGauges

When following a published design you will probably use thethread sizes as recommended by the designer If you are

making a thread to match an existing thread however youneedtofigureoutwhattheexistingthreadisThisiseasiesttodoonanexternalthreadIfyouhaveonlythenuttrytofindaboltthatwillfititandusethattocheckthethreadIfyoucanrsquotfindamatchingboltandtheholeinthenutisbigenoughyoucouldtrypressingabitofplasticineintotheinternalthreadandmeasuringthatTomeasuretheexternalthreadweneedtodeterminethree

thingsusingathreadpitchgauge theoutsidediameterof thethread the pitch of the thread and the thread angle Thesethree checks will probably be sufficient to decide what thethreadactuallyisBritish threads such as British Standard Fine and British

Standard Whitworth and also the Model Engineer threadsystemhaveanangleof55degreesAmerican threads such as UNF (Unified Fine) UNC (Unified

Coarse) UNEF (Unified Extra Fine) ANF (American NationalFine)ANC(AmericanNationalCoarse)are60degreesasisISOmetricUnusually theBritishStandardCycle thread is also60degreesThe other thread youmight come across is the BA (British

Association)threadThishasathreadangleof47frac12degreesandismetricbasedThelargestBAthreadis0BAwhichhasa6mmdiameterwith a 1mmpitch TheBA series godown to 22BAbutinpracticeyouareunlikelytocomeacrossanythingsmallerthanabout14BA

TAPS

TappingistheprocessofcuttinganinternalthreadwithatapFirst a hole is centre drilled and drilled in the workpiece Irecommend that you give the top of the hole a 90-degreecountersinktogivealead-intothetapandalsotostopthetapfromthrowingupaburrontothefaceofthework

Setofhandtaps

TypesofTap

The many types of tap can be divided into hand taps andmachinetapsHandtapsarenormallyheldinatapwrenchbutcan be held in the lathersquos tailstock chuck or a purpose-madetailstocktapholder

Close-upofahandsecondtap

WhentappingbyhandstartthetapuntilitstartstobiteandgiveitanextraturnorsoReversethedirectionofthetapforaturn to break the chip Continue forward for a couple of turnsand then reverseasbeforeContinue todepthor through theworkpiece by continually tapping a couple of turns reversingandcontinuingforwardThisshouldclearthechipsandpreventthetapfrombreakingIfthetapgetshardtoturntakeitrightoutoftheholetoclearanyswarfaddsomemorelubricantandcontinuetappingA set of hand taps will normally comprise a taper tap a

secondtapandaplugtapUsuallyyouwillstartaholewithataper tap This is a tap where the outside of the thread isreducedtowardsthepointbygrindingitonataperThistypeoftap can be used to start the hole but if the hole goes rightthrough the work it may be possible to screw the tap rightthroughtheholesoformingafullthreadrightthroughIfthetapertapistooshortorifyouaretappingablindhole

youneedtofollowthetapertapwiththesecondtapwhichhasmuch lessofa taper In fact itonlytapersrightat thestartofthetapTheplugtapisfinallyusedusuallytofinishoffablindhole

Theplugtaphasnotaperonitjustashortlead-inontheendBetween the three you should be able to tap themajority ofholesintheworkshopWhentappingblindholesitisbesttoworkoutthedepthand

fromtherethenumberofturnsneededforthetaptoreachthebottomoftheholeAsanexamplesaytheholeis9mmdeeptothepointThe tapenters2mminto theholebeforestarting tocutSo9mmless2mmgives7mmThepitchofthetapis05mm7mmdividedby05equals14sothenumberofturnstothebottomoftheholeis14Inpractice12or13turnswillbethemaximumneededWhen tapping blind holes make sure that all swarf is

removedfromthebottomoftheholebeforestartingtotap

Selectionoftapholders

HoldingTaps

TherearetwomaintypesoftapwrenchthehandtapwrenchwhichisdesignedtobeheldwithbothhandsandtheTeetypetapwrenchwhichoncestartedcanoftenbeusedone-handedTapsusuallyhaveeitheracentreholedrilledintheshankor

theshankisgroundtoapointThismeanswecansupportthetapfromthetailstockeitherbyusingalathecentreorbyabitofbarinthetailstockchuckwithafemalecentreinitTeetypetapwrenchesoftenhaveafemalecentreintheendandcanbesupported on a running centreWhen the tap is supported bythe tailstock at one end and the hole in theworkpiece at the

otheritmustbeinlinewiththeholeintheworkpiece

Machinetap

MachineTaps

Themaintwotypesofmachinetaparethespiralpointandthespiral flute The spiral point pushes swarf downwards throughthe hole while the spiral flute pulls the swarf out of the holeSpiralflutetapsaremuchweakerthanspiralpointtapsandintheory should not be used for tapping by hand However inpractice you can often get away with hand tapping using aspiralpointtapifyouareverycarefulIneithercasethetapisdesigned for continuous rotation swarf being automaticallycleared so the regular reversal as with a hand tap is notnecessaryIf you are careful you can probably get away with using a

hand tap under power but only do this with a hand-held tapholderwhereyoucanquicklyletgoifthetapstartstostickYou can also getmachine taps thatwill cut a thread under

powerbyscrewingthroughthejobwithoutstopping

Spiralflutetap

SpeedsforTapping

Tappingspeedsshouldbe low lowbackgearspeedshouldbefineWhenyouhavetappedtheholetodepthorrightthroughtheworkpiecestopthelatheandspinthetapoutbyhandThiswillbequickerthanreversingthelathe

ThreadingfromtheTailstock

For small taps you can use the sensitive drilling attachment(seeChapter11)orifthetapislargeryoucoulduseaslidingtapholderThiscanbeassimpleasachuckmountedonataperat one endwith a parallel hole through the chuck shank ThechuckthenslidesonabarheldinthemaintailstockchuckForlargetapsyoucanuseatommybartostopthetapholderfromturningbutthetommybarshouldnotbesolongastofoulthelathebedoranyotherpartofthemachineifyouhavetoletgoInfactitisfarsaferifyoudonotusethetommybartothreadunderpower

DIES

Dies also come in carbon steel andHSS versions The outsidediameterofadieoftenvarieswiththesizeofthethreadbeingcutalthoughthediameterwillbetooneofasetstandardDiesusually have themakerrsquos name and the thread details on thefrontof thedieThis is theside that ispresented to theworkThediewill havea short lead-in if this isnot requiredon thefinishedthreadyoucanreversethedieanditwillcleanuptoashoulder

SlidingtapholderSlidingdieholdersarealsoavailable

When cutting a thread especially a small one it pays tomaketheinitiallengthofthreadlongerthanthatrequiredThisissoyouhaveabitat thefronttoplaywithtogetthethreadright Then you can part off the excess length leaving a goodthreadoftherequiredlengthDies are usually split so you can adjust them to cut a size

threadIdeallyyoushouldhaveadieholderforeachdiesoyoucansetthedietocutsizewithouthavingtoresetiteverytimeyouchangethedieThedieshouldbesetsothatitcutsasizethreadinonepassDie nuts are often hexagonal in shape They are used to

cleanupanexistingthreadthat isdamagednot tocutanewthreadfromscratchFor each thread you are going to cut you should make a

home-madegaugetappedwithyourowntapWhenyoucutthethreadanditfitsthisgaugeyoushouldthenhaveagoodbutnottightorloosethreadYoushoulduseatailstockdieholderwithaslidingbodywhen

threadingfromthetailstockasthiswillholdthedietruetothethreadIdeally the tailstock die holder should be knurled and also

haveatommybarholeforeaseofuseThe speed for threading with a die in the lathe should be

quitelowamaximumof60rpmshouldbefineformostjobs

SCREWCUTTINGATHREAD

Whilecuttingathreadwithtapsanddiesisperfectlyadequatefor most applications the ability to cut an accurate screwthreadbyusingthelatheisaveryusefulfacilitytohaveIfthethread is large or non-standard taps and dies may not beavailable or they may be so expensive as to be out of thequestionforuseintheamateurrsquosworkshopVariouspitchesofthreadcanbecutbythesimpleexpedient

of changing the configuration of the change gears or alteringtheleversonthescrewcuttinggearboxifoneisfittedWewillconcentrate on a lathe with change gears if you have ascrewcutting gearbox please refer to the manufacturerrsquoshandbookMost lathes that youwill comeacross are likely to have an

imperialpitch leadscrewThiswillbeapitchofsomany teethper inch (TPI) Typically this will be 4 or 8 TPI although otherpitchesareavailableForourexamplewewillbeusingalathewithan8TPI leadscrewandasetofchangewheelscomprisingthefollowingnumbersofteeth2times202530353840455055606570and75

SETTINGUPTHECHANGEGEARS

Letrsquostakeatypicalthreadpitchof20TPIForeveryturnofthemandrel the leadscrew needs to move forward 120in Thismeans we have to set the change gears so the mandrel toleadscrewturnratio iscorrect Inpracticethemandrelgear islikely tobe20 teethand this is unlikely to change nomatterwhat thread we are cutting This means we will change theleadscrew gear which has to have the correct ratio to themandrelTheTPIwewishtocutis20usingaleadscrewwithapitchof

8TPI20dividedby8givesusaratioof251Thismeansthatthe mandrel gear needs to rotate at 25 times the leadscrewgearAsthemandrelhas20teeththeleadscrewgearneedstobe25times20teethwhichisa50toothgearInpracticea20toothgearanda50toothgearmaybetoosmalltotransferthedrive from the mandrel to the leadscrew and intermediategear(s)willneedtobeusedThese gears are called idler gears and they can have any

number of teeth Youmay think these idler gears change theratio of the mandrel to the leadscrew but they do not Theysimply transfer the drive from the mandrel gear to theleadscrew and the ratio stays the same This concept can behardtograspsoIwilltrytoexplainitsimplySay the mandrel gear does one turn This makes the idler

gearorgearsmoveexactly20teethandthisinturnmovestheleadscrewgearexactly20teethAsyoucanseetheratiodoesnotaltertheleadscrewgearmoves20teethforevery20teeththemandrelgearmovesandtheratiostaysthesameThistypeofset-upisknownasasimplegeartrain

Simplegeartrain

Compoundgeartrain

Letuslookatanothercommonthreadpitch32TPITheratioofleadscrewtoTPIis41(8times4=32)Sotheleadscrewgearneeds to be themandrel gear 20 teeth times 4 = 80 teethLookingattheavailablegearswedonrsquothavean80toothgearThismeanswewillhavetouseadifferentmethodtogetour41ratioWithamandrelgearof20teethwecouldusea40toothto

give us a ratio of 21 We are now halfway there but needanotherpairofgearswitha21ratioWedohavea30anda60

toothgearsothiswouldgiveusoursecond21ratioWecouldnot set these gears up as in the previous example howeversince the two intermediate gears would just act as idlers andtheratiowouldbe2150percentoutfromwhatisrequiredWhatwewouldhavetodoismountthe40toothandthe30

tooth gears on the same spindle so they rotate at the samespeedaseachother(The20toothgearmustdrivethe40toothgearandthe30toothgearmustdrivethe60toothgearinthisorder)Thiswouldgiveusthecorrect41ratiothatweneedAswehavemountedtwogearsononespindlethisisknownasasinglecompoundgeartrainDependingonyourlatheyoumayneedanidlergearbetweenthe30toothgearandthe60toothgearAgainthiswillnotalterthegearratiosYou can also have double compoundgear trainswhere two

lots of gears are mounted together on two spindles This istaking us into complicated territory however and I will referreaders to the screwcutting chart provided for their particularlathe Ifyour lathedoesnotcomewithascrewcuttingchartasearchon the Internet should findone that you candownloadandprintoutThemost likely application of double compound gear trains

would be to cutmetric threads with an imperial leadscrew orimperialthreadsover60TPII have tried to keep this explanation of setting up

screwcutting gears simple and the maths to a minimum Theexplanationgiventogetherwiththescrewcuttingchartforyourlatheshouldbemorethansufficienttogetyougoing

ExternalscrewthreadtoolmadefromaCoventry

diechaser

CUTTINGTHETHREAD

The speed for screwcutting should be about mid-back gear ifyouhaveitpreferablysomewherearound30ndash40rpmatmostTherearetwomainmethodsofscrewcuttinginthelatheThe

firstoneinvolvesthetopslidesetparalleltotheworkandintheothermethodthetopslideissetonanangletothework

Externalsinglepointscrewthreadtoolsettinggauge

Cuttinga20TPIThreadwiththeTopSlideParallel

For a 20 TPI Whitworth thread the pitch is 0050in and thethreaddepthisaconstant064ofthepitchsothethreaddepthis 0050 times 064 = 0032in This is the depth the cross slideshouldbewoundinWhilethedepthofthreadis0032inyoualsoneedtomove

the top slide forwardat eachpass Fora standardVee threadthisneedstobehalfthein-feedofthescrewcuttingtoolsoyoumovethecrossslideinby0010inandmovethetopslidealongbyhalfthis0005in

Cuttingascrewthreadwiththetopslidesetparalleltothelathe

Cuttingascrewthreadwiththetopslidesetatanangletothelathe

Theendresulta20TPIfinishedthreadbeforetidyinguptheendandundercutting

Cuttinga20TPIThreadwiththeTopSlideatanAngle

This angle will vary according to the thread being cut but itshouldbeabout1degree less thanhalf the includedangleofthethreadforaWhitworththreadof55degreesforexampletheangleshouldbehalfof55degreesminus1degreegiving265degreesNotethattheangleistakenwiththetopslidesetat90degreestotheworkWiththetopslidehandlefacingyou(at90degreestohowit isnormallyused)rotatethetopslidethe required number of degrees (265) to the right Beginnersoften rotate the top slide 265 degrees to the left from thenormalpositionwhichwouldgivean included threadangleof127degreesThisisclearlywrongBecausethetopslideissetonanangleyouwillneedtofeed

thetopslideinfurtherthanifthetopslideissetparalleltothelatheYoucan findthe increaseddepthof threadbyusingthefollowingformula

c=bcosineofA

whereAistheanglecalculatedathalftheincludedthreadangleminus1degreegiving265degreesb is thedepthof thread(forWhitworththreadsthisis064timesthepitch)andcisthecalculatedangulardepthofthreadFor a 20 TPIWhitworth thread the pitch is 0050in and the

threaddepthisaconstant064ofthepitchsothethreaddepthis0050times064=0032inThecompensateddepthofthreadisthen0032individedbythecosineof265degrees=00357

UsingtheThreadCuttingIndicator

With an 8 TPI leadscrew if the thread being cut has an evennumber of threads the leadscrew can be engaged at anypositionof the threadcuttingdial indicator If the thread isanoddnumberyoushouldusethesamenumberoranyalternatenumberthatisoneorthreetwoorfourForthreadswithahalfpitch always use the same number For metric threads orpeculiar numbers do not disengage the clasp nuts withdrawthescrewcuttingtoolandreversethemotoruntilthetoolgoesback to the start If the thread is an exact multiple of theleadscrewtheclaspnutscanbeengagedatanypositionIfindoubtalwaysengageatthesamenumberoneIttakes

verylittletimetotraversetheextradistancerequiredFor leadscrews other than 8 TPI please refer to your lathe

manual

AcknowledgementsandUsefulContacts

I would like to thankMy TimeMedia Ltd (Publishers ofModelEngineer and Model Engineersrsquo Workshop) Ken Wilson TonyJeffreeandTranswavePowerCapacitorsLtdfortheuseoftheirphotographs

USEFULCONTACTS

UnitedKingdom

ArcEuroTradeLtd10ArchdaleStreetSystonLeicesterLE71NATelephone01162695693Fax01162605805EmailinformationarceurotradecoukhttpwwwarceurotradecoukSuppliersofmachinetoolsandaccessories

ChesterMachineToolsHawardenIndustrialParkHawardenChesterCH53PZTelephone01244531631EmailsaleschestermachinetoolscomhttpwwwchestermachinetoolscomSuppliersofmachinetoolsandaccessories

CowellsSmallMachineToolsLtdTendringRoadLittleBentleyColchesterEssexCO78SH

ModelEngineersrsquoWorkshopintroducedin1990isarelativenewcomertothemodelengineeringsceneItdealsmainlywithtoolsandprocessesandisnowpublishedeveryfourweeks

ModelEngineerwhichcurrentlyappearseveryfortnighthasbeenpublishedcontinuouslysince1898Itismainlyaboutmakingprecisionmodelsbutoftenincludestechniquesforturninginthelathe

I would like to pass on some of this knowledge This bookMetal Turning on the Lathe is the first of three for CrowoodPressonaspectsofworkshopengineeringitwillbefollowedbyMilling and Introduction to Workshop Tools and TechniquesEachbookwillbeacomprehensiveguideforboththeamateurandprofessionalengineerAlatheisessentialtoallbutthemostbasicofworkshopsIt

enablesyoutoproduceturnedcomponentstoahighdegreeofaccuracywiththeminimumofeffort

ThebasicMyfordmodeltheML7wasmanufacturedformanyyearsTensofthousandsarestilltobefoundingaragesfactoriesandhomeworkshopsaroundtheworldThisistheprototypeML7LatheasrebuiltbyMyfordLtd

ThelaterML7RandSuper7modelswerefittedwithaclutchasstandardThissaveswearandtearontheelectricalcomponentsandthemotorTheyalsohadmorespeedsLaterversionsoftheSuper7canbefoundwithapowercrossfeedTheillustrationshowstheprototypeSuper7latheagainithasbeenrebuilttofactorystandardsbyMyfordLtd

TheAtoZofalathe(A)Changewheelguard(B)Countershaftpulleyguard(C)Drivebeltguard(D)Countershaft(E)Belttensionlever(F)

Oiler(G)Motor(H)Tumblergearoperatinglever(I)Headstock(J)Backgearoperatinglever(K)Mandrelnose(L)Left-handleadscrewbearing(M)Leadscrew(N)Halfnutoperatinglever(O)Toolclamp(P)Topslide(Q)Crossslide(R)Saddle(S)Apron(T)Carriagehandwheel(U)Screwthreadindicator(V)Lathebed(W)Rack(X)Tailstock(Y)Tailstockhandwheel(Z)Right-handleadscrewbearing

AnearlyMyfordlatheAlthoughverybasicitcandoalotofusefulworkintheworkshopespeciallyiftimeisspentonmakingafewsimpleaccessories

This book will show you how to use the lathe safely andeffectively in your workshop but first you should ensure thatyou are familiar with the main parts of the lathe and theirterminologywhichmaybefoundonpage9Chapter1ofthisbookisaboutchoosingalathewhatsizeof

lathe to buy the different types available desirable featuresandwhetheryoushouldbuyneworsecond-handChapter 2 covers installing a lathe how to lubricate it and

maintain it in good condition and advice on general safety inyourworkshopwithparticularemphasisonhowtousea lathesafelyChapter3will lookatthematerials fromwhichcuttingtools

aremadeaswellastheirbasicshapeandgeometryThenwe

willlookatselectingsuitablespeedsandfeedsChapter 4 dealswith sharpening lathe tools andhow to set

themupinthelatheChapter 5 covers the different types of chucks how to use

themandsetworkupaccuratelyinthemChapter 6 teaches you basic turning between centres and

then introduces turning with the work mounted on the lathefaceplateChapter7isaboutholdingworkinacolletandhowyoucan

make and use several different types of mandrel forworkholdingChapter 8 explains how to turn a taper using the top slide

theuseoffixedandtravellingsteadiesandmakingaformtoolChapter9explainshowtousedrillsandreamersinthelathe

includinghowtoselectthecorrectspeedsandfeedsChapter 10 shows the different ways to bore holes in the

lathewiththeworkheldinachuckmountedonthefaceplateorheldonthecrossslideChapter 11 explains how to use knurling tools and radius

turning tools as well as making simple form tools and basicproductionmethodsChapter 12 shows you how to use taps and dies to cut

internalandexternal threads in the lathe Italsoexplainshowto set upa simplegear train and cut a screw threadwith thehelpofascrewcuttingdialindicator

1BuyingYourFirstLathe

WHATSIZEOFLATHEDOIREQUIRE

ThefirstthingtoconsiderwhenbuyingalatheisthesizeoftheworkthatyouwanttodoWhatisthelargestdiameteryouwillwanttoturnonitandwhatisthelongestlengthyouwillneedtoturnA3frac12times18in(90times457mm)lathewillallowamaximumdiameterof7in (178mm) tobe turnedover the lathebed thelatterfigureisknownastheswingInpracticethoughthisisatheoreticalmaximumas it is stillnecessary toholdandclampthe article being turned The swing over the cross slide isusuallymuchsmallertypically2in(50mm)Many lathes however aremanufacturedwith a gapbed at

the headstock end to enable short items of a large diametersuchaslocomotiveortractionenginewheelstobeturnedLathes are also sometimes available as standard and long

bed lathes The long bed lathe as the name suggests allowslongermaterial to be turned within the capacity of the latheWhen turning longermaterial the diameter will be limited bytheswingoverthecrossslideThiswillbealotsmallerthantheswingoverthebedIfbuildingamodelsuchasatractionengineoralocomotive

the deciding factor for the size of lathe is likely to be thediameterof the largestpairofwheels thatneed tobe turnedBefore deciding on the size of lathe required you shoulddetermine the size of the largest diameter and the longestlength of material that needs to be turned Another factor indeterminingwhat lathe tobuy is theavailabilityof sparesand

accessoriesisthecompanystilltradingwillitstillbetradinginthe future and are there large amounts of secondhand partsandaccessoriesavailablefromtooldealersoroneBay

Atypicalinvertertoconvert240voltssinglephaseto240volts3phase

LATHEELECTRICS

Single phase electric is where the lathe plugs into the mainssupplyinyourhouseThemotorwillhavetheusualliveneutraland earth leads Lathes supplied for factory use usually havethree phase motors and require three live wires each of adifferentphaseThinkofaphaseasan incomingwaveon theseashore three successive waves make up the three phasesneededEachphaseisthesameastheprecedingonebuttheyareoutofsyncandallpeakatadifferenttime

Aforwardreversecontrolboxforaninverter

Convertersandinverters

Youcan runsome3phasemotors fromasinglephasesupplyviaaconverteroraninverterThemotor informationplatewillusuallysay240volts440voltsif it iscapableofrunningonaninverter Inside the motor there will be changeover tags tochange the motor from 440V down to 240V Follow theconverterinverter manufacturerrsquos instructions for furtherinformation It isnotusuallyverycomplicatedto runa240V3phasemotor from an inverter and thiswill give a quieter andsmoother running motor than a single phase supply canprovide This usually requires some simple programmingexplainedintheinverterrsquosinstructionsanditusuallytakesfiveminutestogetthemotorworkingproperly

ThismotorispartoftheinverterpackageshowninthepreviousillustrationNowiringisinvolvedasthemotorleadplugsstraightintotheinverterbox

Theinverterrunsataconstantvoltagebutthespeedofthemotor will change as the frequency is raised or lowered Isuggest limitingyour inverter from full speed tohalf speed sothatthefanstillcoolsthemotorandstopsitfromoverheatingyoucanthenusethebeltstochangethemainspeedstepsasusual(Ifyoumustuseveryslowrunningitispossibletoaddaseparatefansuchasacomputercoolingfantogiveconstantairflow) Most inverter suppliers offer a forwardreverse andspeedcontrolboxthatcanbesetupinaconvenientpositiononthe machine These are well worth fitting for convenience inuse

Thisinverterisdesignedformountingonthefrontofthelathe

While inverters are designed to run only onemachine youcangetconverterstopowermorethanonemachineatatimeDependingonthesizeandpoweroutputconverterscostaboutthreetofourtimesasmuchasaninverterTherearetwomaintypesofconverterRotaryconvertersare

designedtorunmorethanonemotoratatimeThisis ideal ifyouwanttorunmorethanonemachineortwomotorsononemachineforexamplethemainmachinemotorandperhapsanauxiliary motor that drives the machinersquos coolant pump orpowerfeedsystem

Arotaryconvertercapableofpoweringmorethanone3phasemotor

ThesecondtypeisthestaticconverterwhichisdesignedtorunonemotoratatimeThereisofcoursenothingtostopyouusingthestaticconverteronmorethanonemachinebyfittingasuitablefemaleelectricalconnectortothestaticconverterandmatchingmaleconnectorstotheindividualmachinesThiswayyoucanconnectthestaticconvertertoonlyonemachineatatime

Thisstaticconverterissuitableforpoweringone3phasemotorIfyoufitasocketontheoutputhoweverdifferentindividualmachinescanbepluggedintoitoneatatime

Theelectricalloadingonrotaryorstaticconvertersmustnotexceed theirmaximumrating If indoubton the loadcapacityneeded to run your machine(s) you should consult the

manufacturerorsupplieroftheconverter

AnearthleakagetripisidealforquicklyeliminatingamotorwheretheelectricalinsulationisbreakingdownItisusefulfordetectingcertainelectricalearthingfaultsbutshouldnotbeusedasaguaranteeofelectricalsafety

Simpleelectricaltestingandsafety

Whenbuyingasmallsinglephasesecondhandlathetakewithyouanearth leakage testerof the typeused for lawnmowersandothergardentoolsIonceboughtaUnimat3lathetookithomeandpluggeditinItkeptblowingtheearthleakagetripinthefuseboxeventhoughithadworkedperfectlyatthesellerrsquoshouseIsolditonatalossbutthebuyerdidknowtherewasaproblemwiththeelectricsIt is most important that the metal parts of any lathe are

connectedtotheearthwirewhichisinturnconnectedtoearthMake sure that themotor frame is also connected toearthassome motors have dampening rubber mounts that insulatethem from themachine itself If in doubt about any aspect ofelectricalinstallationpleaseconsultaqualifiedelectrician

Acontinuousbedisidealwhenworkingwiththefaceplateorwithcollets

LATHEBED

Thelathebedisthebackboneoftheentirelatheandisthepartthat is mounted on the bench or stand There are two maintypesoflathebedtheplainbedandthegapbedTheplainbedisusuallycontinuousallthewayalongitslengthwhilethegapbedhasas itsnamesuggestsagap in thebedThis isnotaliteralgapbutasteppedsectionthatallowsbiggerdiameterstobeturnedthanyouwouldotherwisebeabletoturnonaplainbed latheThisgap isameansofmakinga lathesmaller thanwouldberequiredforaplainlatheabletoturnasimilarsizeof

componentSome continuous lathe beds have a section next to the

headstock that can be removed to increase the diameter thatcanbeturnedThisfeatureisusuallyonlyfittedtolargerlathessuchasaremostlyfoundinfactoriesSome lathes have hardened beds although most are just

plaincast ironTherearethreemaintypesofbedwayscalledshearstheplainflatbedwithsquarewaysabedwithaflattopand a 60 degree dovetail at each side and a bedwith raisedandinvertedVeewaysOnthelastofthesethetailstockusuallyrunsononesetofVeesand thecarriageonadifferent setofVees resulting in lesswear to themain slidesWidebedsarebetterandmoreaccurateasthelathecarriageislesslikelytotwistonawidebed

Close-upviewofatypicallathebedwithagapAgapbedlathehasalargerturningdiametercapacitythantheequivalentsizedcontinuousbedlathe

Someveryearly lathessuchas thosemadebyDrummondhad a round bed Although they worked well there is noadjustmentforwearinthelathebed

TheMyfordrangeoflatheshasasquareformofbed

ThistypeofbedhasaflattopwithaninvertedVeeateachsideTheVeesareusuallysetat60degreesbutcanvarywithdifferentmakers

The Unimat SL lathe was sold for many years and manysecondhandexamplesarestillavailableThismodeldiffersfrommostlathesinthatithastwosteelbarsasabedThisisnotaproblemhoweverastheUnimatisintendedonlyforverysmallandlightweightmodel-makingworkandthereistheadvantagethatthebedcanbereplacedbyfittingnewbarsWhen buying a secondhand lathe it is most important to

checktheconditionofthebedYouneedtomakesurethebedis reasonably free from dings rust and hacksaw marksHacksawmarksneartheheadstockareoftencausedbysawing

offworkwhile it isheld inthechuckdingsareusuallycausedbydroppingthechuckonthelathebedwhenscrewingitonoroffthemandrelAsimplechuckboardplacedonthebedwhilefittingorremovingthechuckwillprotectthebedItisalsoidealfor protecting the bed when filing or hacksawing work in thechuck

AlathebedwithraisedandinvertedVeesThecarriageusuallyslidesononesetofVeesandthetailstockslidesontheother

AmodernChineselathebedwithaninvertedraisedVeeThecarriageandtailstockusuallyslideonthesameVee

Wear ismost commonly found at the headstock end of thelathe as a result of machining many short components andrelatively few long ones Make sure the lathe carriage isproperlyadjustedattheheadstockandthenrunitalongasfaras you can towards the tailstock The carriage should bereasonablyfreebutnotlooseallthewayalongthebed

OldroundbedDrummondlathesarestillavailablesecondhandThisparticularexampleistreadledriven

AflatbedlathewithsquarebedwayssuchasaMyfordcanbe checked for wear on the lathe bed using amicrometer orvernierCheckovertheworkingpartofthelathebedonwhichthe carriage slides rather than the part that is not used forguidance Check both the width and the thickness of the bedwaysThetailstockshouldalsobeagoodslidingfitonanyguiding

surfaces Wear is most likely to be found on the tenon thatslidesbetween thebedwaysAworn tenoncouldprobablybereplacedbutthereisnotmuchyoucandoifthetenonguidesarewornTheonlyway to fixawornbed requiresacompletebedregrindThisislikelytobeexpensivesoitwouldbebettertolookforanunwornlatheDecentunwornlathesareouttheresincemanymodelengineersmayhaveboughtthemnewfortyorfiftyyearsagoandhardlyusedthem

TheUnimatSLisaverypopularsmalllatheItsbedconsistsoftwosteelbarsthatcanbereplacedveryeasilywithsilversteeliftheygetwornormorelikelywhentheygetrusty

Asimplewoodenchuckboardwillprotectthelathebedfromdingsandhacksawmarks

LATHEHEADSTOCK

Theheadstockisthelargecomponentmountedattheleft-handside of the lathe bed It needs to have good bearings An all-gearedheadwillalmostcertainlyhaveballorrollerraceswhilethe older type of lathe for amateurs may well have plainbearings either phosphor bronze or whitemetal These areperfectlyadequatebutyoushouldmakesurethere isnowearinthemSomelathesalsohaveamandrelthatrunsdirectly inbored holes in the cast iron headstock casting Plain bearingswillbeperfectlysatisfactoryas longasadequate lubrication isused

Close-upviewofaMyfordheadstockonanML7RNotethelargebronzebearingatthefrontTheearlierML7latheshadwhitemetalbearingsalthoughtheC7capstanhadbronzebearingsandahardenedlathespindle

Tocheck forwear in the lathersquosbearings fitachuck to themandrelandputadialtestindicatorontopofthechuckGentlytry levering the chuck up and down by using a steel bar orsimilarheldinthechuckYouarelookingforminimalmovementhereespeciallyonaheadstockfittedwithballraces

CheckingthelathebearingsforwearAnymovementupanddownindicateswearinthebearing

The mandrel is mounted in the headstock and is usuallythreaded to take a chuck or faceplate The lathersquos mandrelshould not move back and forth in the bearings If it doeshowever itwillprobablybepossibletoadjust ittocorrectanyendwise movement The mandrel should not be too stiff butshouldturneasilybyhandWhentestingalathemakesuretheheadstockbearingsare

correctlyadjustedsothatwherepossiblethereisnoplaySeta tool up take a trial cut alonga length of bar and check forchatter If you are using a correctly set tool and a suitablespeedchatterisasuresignofwornbearings

Manylatheshaveathree-orfour-stepdrivepulleyasthesecondstageofthedrivechain

POWERDRIVE

Manylatheshaveathree-orfour-steppulleyonthemandreltotake the drive from a similar pulley on the countershaft Thecountershaft is in turn driven from the motor which is oftenmounted at the back of the headstock and completes theintegral drive system that is so popular on most amateursrsquolathes

Thisparticularlathehasatwo-stepmotorpulleyandcountershaftwhichdoublestheavailablespeeds

SpeedchartonthebeltguardofaMyfordML7Rlathe

AfewlatheshaveaclutchfittedasstandardorasanoptionalextraTheclutchsaveshavingtostartandstopthemotorwhileitisrunningThishelpstostopwearandtearonthemotorandelectricalsystemAdifferenttypeofclutchsystemtheTriLevaspeedselector

wasonlyfittedtoMyfordML7orC7lathesThishasthreeleversfor setting threedifferent speedsDependingon the leveryoudepressyougetahighmediumorlowspeedIfyoupressoneof the levers downwhile another is right down the first leverwilldisengagethesecondsostoppingthemandrelfromgoinground If the lathe is switched off and all three handles aredepressed the mandrel is locked preventing rotation This isusefuliffilingorhacksawinginthelathe

TheclutchisnormallymountedinsidethelargecountershaftpulleyItisusuallyoperatedbyaleverattheright-handsideoftheheadstockattachedtoapushrodthatpassesrightthroughthecountershaft

TheMyfordTriLevaattachmentwillonlyfitML7andC7lathesandisnotsuitableforML7RorSuper7lathes

Therehasbeenatrend inrecentyearstodoawaywiththecountershaftandpulleysystemandtoreplacethemotorwithavariable speed one with an electronic controller This isacceptable except that at low revolutions it does not providethe torque that can be obtained from a countershaft systemThereisalsothedisadvantagethatthereisnowaytodrivethelatheifthecontrollercircuitboardfailswhereasyoucanjustfita new one if the belt breaks The board could of course befixed provided that a circuit diagram is available and theelectronic components can be identified Sometimes thecomponents are marked with internal house numbers ratherthan commercially recognized part numbers that can beorderedasareplacementfromacatalogueSomeboardsmighteven have the identification marks removed to make repairsalmostimpossible

ThethreadedendofalathemandrelisdesignedsothatthechuckbackplaterunstrueIfthechuckmountingfaceofthebackplateismachinedinsituthechuckshouldruntrueaswell

CHUCKMOUNTINGSYSTEMS

The threaded lathe mandrel nose is not by itself a suitablelocationforachuckorfaceplatesothenoseisusuallygivenaturned register on which to locate the chuck The chuck isscrewedrightontothemandrelovertheregisterandbuttsuptoaturnedcollartokeepthechuckrunningtrueTheothersideof the mandrel collar butts up against the main headstockbearingwhichusuallyactsasathrustfaceThemandrelisusuallyboredthroughandmachinedtotakea

MorsetapercentreforturningbetweencentresDonotputyourfingerineitherendofthemandreltocleanitwhilethelatheisrunningAneasywaytocleanthetaperintheheadstockiswithabottlebrush often sold in chemists to cleanbabiesrsquo bottlesAnalternativeisasoftfeltshotgunbrushdonotuseonemadefromwire

ThislathehasaplainregisterAccuracyreliesonthelathechuckbeingagoodfitontheregister

There are various systems of chuck mounting in useespeciallyon the larger lathesTheproblemwith thescrew-ontype with a register mentioned above is that the chuck orfaceplatecanunscrewwhenthelatheisrunninginreverseTheonly timeyoushould run this typeofmandrel in reverseveryslowly and without taking a cut is if you need to return thescrewcuttingtooltothestartofthethreadyouarecuttingAlternativespindlenosescanbeaplaindiscwitharegisterto

boltthechuckontooracamlockwherethechuckisheldontightlybyturningstudstolockthechuckontothemandrelTheplain discwith register relies on having chuckswith amatingregistertoworkproperly

AnAmericanstandardCamLockchuckmountingbackplateandCamLockchuckplatefittedtoachuckTheyareusuallyfittedtolargerindustriallathes

TheAmericanDstyleCamLocksystemeithertakesachuckor faceplate directly or it has a backplate that can have aregisterturnedonittosuittherequiredchuckAlthoughmanylathe mandrels with Cam Lock fittings have six holes thematchingchuckorfaceplateoftenhasonlythreelockingpinsThe advantage of both of the last two systems is that they

canberuninreversewithoutthechuckcomingoffthemandrel

Theleadscrewisdrivenfromthemandrelviaageartrain

SCREWCUTTINGGEARS

The left-hand end of the mandrel will often have a gearmountedonittodrivethechangewheelgearsandleadscrewThe mandrel gear usually drives a pair of gears called

tumblergearswhicharemountedona leveratthe leftoftheheadstock The direction of the leadscrew can be changed bybringingeitheroneortheotherintogearbyraisingorloweringaleverThereisusuallyacentralneutralpositionwhereneithergearisinmeshThissaveswearonthelathechangewheelsandleadscrew bearings as well as reducing noise while workingMandrelandtumblergearswillbediscussedfurtherinChapter12whenwesetupascrewcuttinggeartrain

A set of changewheels usually comprises about a dozengearsbutthiscanvarydependingonthemanufacturerThesechangewheels which take the drive from the tumbler gearsdown to the leadscrew are mounted on moveable studs toensurethegearsareinmeshwitheachotherDependingonthenumber of gears in the train the leadscrew will turn eitherclockwiseoranti-clockwiseThedirectionof the leadscrewcanbe reversed using the tumbler gears to enable right-hand orleft-handthreadstobecut

Oftentherearetumblergearsinthegeartrainthatcanreversethedirectionoftheleadscrew

YoucanusuallysetthegearstocutaveryfinepitchsothattheleadscrewactsasaselffeedwhenturningfromthesaddleIf you anticipate the need to do any screwcutting check thatthesuppliedscrewcuttinggearswilldotherangeofpitchesyourequire It has been known for certain lathes to be unable tohandle somecommonpitches a typical examplebeing26TPI(teeth per inch) A pitch of 26 TPI is often needed to repairmotorcycles and bikes made before the introduction ofmetrication

MakesurethatafullsetofchangegearsisincludedwiththelatheIfnottheyarereadilyavailablesecondhand

LEADSCREW

The leadscrew ismounted at the front of the lathe there areusuallybearings to support the leadscrewateitherendof thelathe bed It is used tomove the lathe saddle along the bedeither for a self acting feed or for screwcutting Some lathesalso have a graduated handwheel mounted at the right-handendoftheleadscrewforturningthemandrelbyhandSome of the larger lathes also have a separate feed shaft

whichisusuallyaplainroundshaftwithakeywaycutalongittodrivethesaddleusingafinefeedThissaveswearandtearontheleadscrewwhichisthenonlyusedforscrewcutting

Mostleadscrewscanhaveagraduatedhandwheelmountedontheright-handendoftheleadscrew

SCREWCUTTINGFACILITIES

Ausefulfeatureonanylatheistheabilitytocutscrewthreadsof different pitches Leadscrews come in different pitches acommon one being 8 TPI but many variations are fitted todifferent lathes including leadscrews with a metric pitch It isawkward tomachinemetricscrewswithan imperial leadscrewandviceversaSometimesmetricconversionsetsareavailablebuttheycanbehardtofindareusuallyexpensiveandrequirethe lathe to be changed over often using 127 tooth gearwheels This figure is derived from multiplying the metricequivalentof1in(254mm)byfivea127toothwheelisthusadirectconversiontoametricthreadonalathewithanimperialleadscrewA127 toothgear isusuallyvery large if itmatchesthepitchoftheremainingscrewcuttinggearsbutyoucouldusesmallergearswitha smallerDP (diametralpitch)but stillwith127 teeth Youwould also need amatching gear of say fiftyteethtogiveyoua2541ratio

Thislathehasbothaleadscrewforscrewcuttingandadriveshaftforthesaddleandcrossslidefeeds

Ascrewcuttingdialindicatorusuallymountedtotherightofthe carriage is a useful feature This is a small dial withdivisionsmarkedonitmountedonashaftTheotherendoftheshafthasagearthatmesheswiththeleadscrewandmakesthedial go roundWhen the clasp nuts are engaged the carriagemoves and as the gear moves at the same speed as thecarriagethedialstopsgoingroundWhen you engage the clasp nuts on the leadscrew the

positionwhereyouengagedependsonthepitchofthethreadbeing cut Some thread pitches allow you to engage at anydivision of the dial while others need to be engaged at aparticularpositionof thedialTheuseof thescrewcuttingdialindicator will be covered in Chapter 12 When using the finefeedyoucanengagetheclaspnutsatanymarkedpositiononthedialsoavoidingweartotheclaspnuts

AtypicalscrewthreaddialindicatorThisoneisengagedanddisengagedbylooseningtheboltandengagingthedrivegearwiththeleadscrew

LATHESADDLEANDAPRON

The saddle is thepart that slides on top of the lathebedandusually has the cross slide and top slide mounted on it Theapron ismounted to the frontof the saddleYoushouldmakesure there isnoplay in the saddle either sidewaysorupanddownandthatittravelsfreelyfromoneendofthelathebedtotheotherwithnotightspotsAtthefrontnearesttheoperatorthereisusuallyapairofclaspnuts(thesearesplitnuts)Thesecan be engaged or disengaged from the leadscrew forscrewcuttingormovingthesaddlealongwiththeleadscrewOncheaper lathes there is usually a solid nut that cannot bedisengaged

ThelathesaddleslidesalongthelathebedTheapronisboltedtothefrontofthesaddle

There is often a rack at the front of the lathe bed thatmatches upwith a handle and gears on the lathe apron Thiscan be used to move the carriage along the bed withoutwearingouttheleadscrewSomelatheshavethecarriagefeedwheel on the right but others have it on the left where hotswarfcanfallontoyourhandsThecheaperlatheshavenorackandrelyontheleadscrewtowindthecarriagebackandforth

ATee-slottedcrossslidemakesthesmalllathemoreversatile

CROSSSLIDE

On top of the carriage is the cross slidewhich canbewoundbackandforthacrossthelathebedWhenusingthecrossslideforfacingacrosstheworkthecarriageshouldbelockedtostopitmovingalongthebedLathesforamateurusearemorelikelytohaveaTee-slottedcrossslidewhilelargercommerciallathesare unlikely to have this facility The Tee-slotted cross slide isveryusefulespeciallyifyoudonrsquothaveamillingmachineYoucanboltworktothecrossslideformachiningusingacutterinthechuckorforboringworkpiecesthataretoolargetoswinginthechuckZero settingdials aredesirable for both the cross slide and

thetopslideTheyallowyoutosetthedialtozerowhichmakesiteasiertomeasuretheamountyouaretakingoffwithonecutInusewindthetooluptotheworkandtouchonsetthedialtozeroandwind the toolbackoff from theworkYounowknowwherezeroisonthetoolandcantaketherequireddepthofcut

withouthavingtoworkitout

Zerosettingdialsmaketurningandscrewcuttingtodepthveryeasy

Apairofzerosettingdialsreadytofit

LathescanbepurchasedwithimperialormetricfeedscrewsMostmodeldesignsareimperialbutmetricismakingheadwayandthismaywellbethewaytogoBewarelatheswithimperialfeedscrewsandmetricdialsTypically thesewillhavea funnynumber of handwheel divisions rather than a whole numberMostofthelathesyoumightcomeacrossareunlikelytohavea

power cross feed for facing This does notmatter as you caneasilywindthecrossslideacrossbyhandTheonlytimeIhavefound a power cross feed to be of use is when I had to faceacross a faceplate to true it up I have trued up similar sizefaceplatesbyhanditjusttookalittlelonger

Thetopslideismountedonthecrossslide

TOPSLIDE

ThetopslideismountedontopofthecrossslideThetopslideisnormallysetat90degreestothecrossslidealthoughitcanusually be swivelled around to various angles for turning ataperanangleorforscrewcuttingSomeofthecheaperlathesdonrsquothaveatopslideasstandardbutitisaveryusefulfeatureif you can get one The top slide should be able to rotateespecially for screwcutting but the top slide handlemay foulthecrossslideincertainpositionssocheckifthisisaproblemTheturningtoolisusuallymountedonthetopofthetopslideItcan either be clamped on directly usually with packing stripsunderneathorthetoolcanbemountedinatoolholdersuchasathree-orfour-waytoolpostoraquickchangetoolpostWewilllook at tool holding methods in Chapter 4 when discussingsettingupturningtools

TAILSTOCK

The component at the right-hand end of the lathe is thetailstock This usually has a handwheel to feed a drill into theworkbut leverfeedandcapstan-style feedingmechanismsarealso available You can lock the tailstock anywhere along thebed The tailstock has a barrel inside it that can bewound inandouttogivealinearmovementtodrillaholeinworkheldinthechuckThetailstockisusuallyboredtoaMorsetaperoftenof a similar size to the headstock so it can take accessoriessuchasdrillchucksmountedonaMorsetaperItcanalsotakeacentre for turningworkbetweencentres It is important thatboth the headstock and tailstock tapers are free frommarksscratchesandburrs

AlathetailstockwiththebarrelextendedNotethatitisnotusuallyaproblemifthechuckkeyisleftinthetailstockwhilenotinuse

Adjustment is usually provided between the base and themain body of the tailstock to allow for setting the tailstock inlinewith theheadstock Tailstocks canbe self ejectingwherethetool isextractedas it iswoundbackwhilesometailstockshavea throughholeandneeda tapwithabar to remove thetool Handwheel depth graduations for drill drilling to a

particularholedepthareveryusefulbutarenotoftenincludedon the cheaper lathes although industrial lathes usually havegraduatedtailstockhandwheelsThebettermakesoflathehavea lever clamping tailstock arrangement while the cheaperlathesoftenhaveaclampingspanneroranAllenscrewclamp

Allguardsshouldbefittedinplacebeforeoperatingthelathe

MACHINEGUARDS

Thedrivemotorcountershaft(iffitted)andpulleybeltsshouldallbeproperlyguarded It isveryeasy togetcaughtup inanunguardedmachineandtheconsequencescanbequitenastyThis has never happened to me but I have seen someonecaught up in a machine and it was not very nice I dorecommend that you make sure your machine guards arecorrectlyfitted

OTHERDESIRABLEFEATURES

Digitalreadoutsareusefulonalatheastheycanshowyouhowmuch to move the handwheels and how much material hasbeentakenoffTheyarequiteexpensivebutyoucan fit themyourself if youare carefulUnfortunatelymost of the cheaperversionsdislikesolubleoilorothercoolantifyougetitintothereadouthead

Adigitalreadoutsuitableformountingonalathe

Youwillneedtwoslidesoneforeachaxis

A soluble pump for cutting fluid is useful and often comesfittedasstandardonthelargerlathesHoweveratinofcuttingoilandabrushwillbegoodenoughformostworkandthatmaysuityoufine

Solubleoilpumpsandreservoirsarereadilyobtainable

Formostjobsyoucangetawaywithsomecuttingoilabowlandabrush

TheMyfordlsquoNortonrsquostylequickchangescrewcuttinggearbox

A Norton quickchange screwcutting gearbox saves time asyou donrsquot have to set up changewheel trains A gearboxhowever considerably increases the price of the averagesecondhand lathe A Myford Norton gearbox has twenty-fourpitchesandiscontrolledbytwoleversReversingtwogears inthe Myford changewheel train gives the gearbox twenty-fourfine feeds insteadof the twenty-fourscrewcuttingpitchesThegearboxhasa setofgearsarrangedasaconeBysliding thelever along and dropping themaster gear onto the cone youcanchangethegearboxratioandsothepitch

TheconegearsinsideatypicalNortonscrewcuttinggearbox(notanoriginalMyfordone)

SeveraldesignshavebeenpublishedtomakeyourownNortontypescrewcuttinggearboxThisoneisavailablefromHemingwayKits

SPINDLESPEEDS

Thespeed rangeneededona lathedependson thework it is

requiredtodoAgoodrangeofspindlespeedsisdesirablewithnoobviousgapsWithelectroniccontrolthisshouldnotbetoomuchofaproblemIdeally a back-geared lathe would be best but this means

either a good secondhand machine such as a Myford or aBoxford or alternatively one of the larger Asian-made latheswithanall-gearedheadstock

Thisbackgeararrangementisswitchedinandoutbyturningthetoggleonthepulleyandliftingaleveratthefrontofthelathe

Backgearnormallyconsistsoffourgearstwolargeonesandtwosmalloneswhichcanbeswitched inorout toreducethespeedofthelathebyaratioofusuallyabout51dependingonthe maker to enable you to turn large diameter workpiecesThis reduction is also essential on a screwcutting lathe asotherwisethemandrelwillbegoingtoofastwhilescrewcuttingandyouwonrsquotbeable tostop in the rightplaceat theendofthethreadIf buying a back-geared lathe check that both gearwheels

havealltheirteethItisamajorjobtostripdownalatheandfitnewgearwheelsassumingtheyareevenavailableassparesCheckthelatheinallgearrangeswiththelatherunningIfa

back-geared lathe or an all-geared head is noisy it could

indicatewearitwillalsobeanuisanceinyourworkshopasnoonewants to hear a noisymachine runningNoise could be amajorproblemespeciallyifyouhaveneighboursnearbyGearedheadsusuallyhaveawiderangeofspeedsthelarger

industrial lathescangoup tospeedsof2000rpmandsmallerversionsareoftenhigher

Anall-gearedheadonamodernindustrialsizelathe

On the more usual amateursrsquo lathe there is often acountershaft usually tensioned by a lever which tightens upthebeltreadyforuseThemiddlespeedofthecountershaft isusually chosen to be about one quarter of the motor speedMost small lathes have three speeds and the back geararrangement adds another three speeds giving six in all TheMyfordSuper7rangeoflatheshavefourspeedsandbackgearmaking eight speeds but there is also a double pulley on themotor countershaft section making sixteen speeds in allalthoughtheverylowestback-gearedspeedswillrarelyifeverbeusedSomeoftheolderColchesterChipmasterlatheshavewhatis

knownasaKoppVariatordriveThis isavariable speeddrivecontrolledbyadialandthesystemworkswellbuttheVariator

isveryhardtoreplaceifthedrivefails

ThissmallCowellslatheiscapableofdecentworkandatthetimeofwritingisprobablytheonlylathestillbeingmadeinBritain

MOUNTINGTHELATHE

There are three main options for mounting a lathe benchmounting portable or on a stand Ideally a makerrsquos standshouldbeusedformountingamediumto large latheandthestandisoftenanintegralpartof larger lathesAsmaller lathesuch as a Unimat or a Cowell can bemounted on a woodenchopping board or a similar small board These lathes can beputawayinacupboardafteruseThe alternative is a workbench but these are often made

from wood which can expand or contract depending on themoistureintheairWoodisnotagoodmaterialfromwhichtomakea stand for a larger latheas itwill attractmoisture andmayexpandshrinkordistortAmetalstandisabetteroptionWewilllookatinstallingthelatheinChapter2

AnArcEuroTradeC3screwcuttinglathemadebySiegThisisaverypopularentrylevellatheandmanyaccessoriesareavailable

Amedium-sizedscrewcuttinglathesuitableforgardenshedworkshops

SHOULDIBUYNEWORSECONDHAND

Beginnerssettingupaworkshopoftenaskifitisbettertobuyanew lathe or secondhand The preceding pages should have

given some guidance but there are more points to be takenintoconsideration

Alargerindustriallathewithafoot-operatedemergencycut-offswitchandbrake

BuyingNew

Thelistoflathesuppliersincludedatthebackofthisbookwereall in business at the time of writing Most will be willing todemonstratetheirrangeofmachinesattheirpremisesorwhileattendingmodelengineeringexhibitionsPaycloseattentiontomechanical noise the general paint finish and the workingslideway surfaceswhich should begroundDoes themachinehave sharpor roughedges (Handwheelsareespeciallypronetosharpedges)The main thing to consider though is the attitude of the

supplier Were they willing to talk to you and answer yourquestionseitheratanexhibitionoroverthephoneHowlongdo they take toanswer thephonewhenyou ring their servicedepartment Do they know the answer to a simple questionstraightawayordotheyhavetogetbacktoyouIsthemanual

written in English or Chinglish (translated awkwardly fromMandarinorCantonese)There are several suppliers of new lathes inmost countries

aroundtheworldbutthemajorityoflathesaremadeintheFarEastOftensupplierArsquosmachinescomefromthesamefactoryassupplierBrsquostheyarejustpaintedadifferentcolourandhavedifferentnamesandlabelsfittedAftersales service can vary greatly Usually companies that

havebeeninbusinesslongerwillofferbetteraftersalesservicebutotherpeoplersquosexperiencescanbefoundonInternetforumsoratlocalmodelengineeringclubsUsually theAsian lathesare reasonablywellmadebut they

often suffer from having plastic gears instead of metal onesOneortwocompaniessupplymetalgearsasstandardso it isworthaskingiftheirmachineshavemetalorplasticdrivegearsSome companies also offer after-market replacement metalgears

BuyingSecondhand

There aremany good quality secondhandmachines availablebut there is also a lot of worn-out rubbish If possible take aknowledgeable friend with you when purchasing a lathe Becareful when buying at online auctions such as eBay MostsellersaregenuinebutsomearenotNeverpartwiththecashuntil youhavechecked the latheover IhaveboughtoneBaywithoutproblemsbut Iamcarefulwhat IbuyandwhofromAsmall latheforacoupleofhundredpoundsisunlikelytobreakthe bank if it is a bit of a dog but a lathe that costs severalhundredpounds is adifferentmatter ThegreenMyfordML7RpicturedthroughoutthisbookwaspurchasedfromeBayItwasbrand new the motor had never been fitted and it was abargainwhencomparedwiththeretailpriceIdidpaycashoncollectionbutIwouldhavewalkedawayif ithadnotmatchedthedescriptioninanywayWhether purchasing new or secondhand check what

accessoriescomeaspartofthepackageandwhatwillneedto

bepurchasedseparatelyEssentialtoolingcanoftendoublethecost of a newmachine if it is not included in the price whilededicatedtoolingmaynotevenbeavailable forasecondhandbargainlathe

Youshouldnowhaveanideaofthesizeoflatheyouneedthefunctionofthedifferentpartsofthelatheandwhetheryouarebuying new or secondhand In Chapter 2 we will look atinstallingthelatheandsafetyintheworkshop

2InstallingtheLatheandUsingItSafely

If you are buying a new lathe completewith delivery to yourworkshopyoucangostraighttothesectiononsettingthelatheupIfyouarecollectingthelatheyourselfhoweveryoushouldpayattentiontoafewwordsonmovingit

Ifyouhaveroomtomanoeuvreanenginehoistcanbeusedtomovemachineryaroundsafely

MOVINGTHELATHE

MOVINGTHELATHE

When going to collect your lathemake sure someonewill betheretohelpyouloaditortakesomeonewithyouUnlessitisaminiaturelatheitwillbetooheavyforonepersontoliftHelpisalsoneededwhenyougetthelathehomeLiftingthelatheoutofacarcanbeharder than lifting it in It isadvisable tohavethreepeoplewhenunloading twoat theheavyheadstockendandoneliftingthelightertailstockendYoucanrentorbuyanenginehoist fora reasonablepriceand this canmakemovingthemachineeasierIf the machine is a substantial industrial type it would be

besttohireatransportcompanythatspecializes inmachineryremovals Professional machinery removers will usually haveproperlyequippedtransporttomoveheavymachinesThiswillprobablyworkoutcheaperthanattemptingtodoityourselfbutmake sure they have insurance in place in case they damagethelatheoryourpropertyYoushouldalsoensuretheyknowithas to beput in place as required in theworkshop youdonrsquotwanthalfatonofmachinerydumpedonyourdrivewithnowayofmovingitintopositionLathesareusuallytopheavywhenbeingmovedandcantip

overifyouarenotcarefulTheMyfordML7seriesforexampleoftenhasthemotorandcountershaftboltedtothebackofthelathe bed and this type of lathewill tend to tip backwards Asimple solution is to bolt two lengths of wood about 4 times 2in(100times50mm)tothelathefeetOneboltineachendwilldoifyou canrsquot drill holes in the correct position This will stop thelathe tipping backwards and also make it easier to lift IfpossibleyoushouldremovethetailstockThisisoftenaheavylumpofmetalbutitisusuallyveryeasytoslideitofftheendofthelathebedAnyotherlargeobjectsthatcanberemovedandreplacedlaterwillmakethelathelighterandeasiertomove

Twoplanksofwoodboltedtothelathefeetwilloftenturnanunmanageablemassofmetalintoaneasilyhandledmachine

Azerovoltsswitchisessentialequipmentonanymachinetool

Wearoldclotheswhenmovingyourlatheandhaveplentyofold rags to wipe off swarf and oil Lay down old blankets ordecoratorsrsquosheetsinsidethecarandasheetofthickcardboardMDForplywoodtohelpprotectthebootareawhenslidingthelatheintothecar

AsmallishlathecanoftenbefittedintoastandardhatchbackorestatecarYoumayfindhowever thatyouhavetodotwotrips one for the lathe and accessories and another for thecabinetthelathestandsonTosaveawastedjourneyIusuallytrytofitthelathecabinetinfirstIfIthenfindthatthecabinetdoesnrsquotfitIcanstillbringthelatheandtoolinghomeknowingthat Ihave tohireavan tocollect thecabinetbutalso that IhavenothadawastedjourneyIfyouhavetosplittheelectricsforexampletotakethelathe

offthecabinetdrawadiagramoftheelectricalconnectionssoyoucanrewirethelathewhenyougetithomeAdigitalcameraisalsoagoodmethodofrecordingthewiringconnectionsbutIwouldnotrelyonthecameraaloneIf the lathedoesnothaveazerovoltsswitch itwouldbea

good idea to fit one after you get the lathe home They areavailable quite cheaply andare easily fitted If in doubt aboutyourabilitytodoelectricalwiringconsultaqualifiedelectrician

Adjustablefeetareveryusefulforlevellingupthelathe

SETTINGUPTHELATHE

Somelathesusuallythelargerindustrialoneshaveanintegral

bedandcabinetThelathecanbesettotruewithjustshimmingunderthefeetorbyadjustingthefeetOther lathes may need to be mounted level and true to

ensureaccuracywhenturningSetthebenchstandas levelasyou can in both directions using a spirit level as a guide Anycheapspirit levelwilldoas longas it isaccurateYoucantesttheaccuracyofaspiritlevelbyturningitround180degreesifitisaccurateitshouldreadthesamebothwaysOnce the stand is reasonably level youcan level the lathe

ThisinvolvesjackingorshimmingupthelatheuntilitistrueinbothdirectionsIfusingawoodenbenchputmetalplatesunderthe feet tospread the loadShimoradjust the latheuntil it isreasonablylevel

Putthespiritlevelonthecabinetrsquoslongitudinalaxisandusetheadjustablefeettolevelthelathe

Insertalengthofbarinthechuckandputadialtestindicatoron top of the tailstock end of the bar Nip the headstock endmounting bolts down first and then tighten down the tailstockendboltsAdjustorshimthetailstockenduntilthereisnosignof movement on the test indicator Next 64repeat theprocedure with the dial test indicator on the front of the barAgainyouare looking fornomovementCheckbothdirectionsagainmakingsurethereisnomovementeitherhorizontallyorverticallywhenyoutightenthelathedownAdjustorshimuntil

there is no movement in either direction when the lathe isclampeddownAslongasthebedisnottwistedthelathebedshouldnowbetrue

1Insertapieceof⅛in(3mm)packingunderthespiritlevelatthetailstockendThiswillresultinarunonthedriptrayandalltheoldoilwillruntotheendofthelathemakingiteasiertocleanup

2Placethespiritlevelonthecabinetcrossaxisandusetheadjustablefeettolevelthelathe

3Putthespiritlevelonthelathecrossaxisattheheadstockendandlevelitasbestyoucan

4Putthespiritlevelonthelongitudinalaxisandlevelalongthelathe

5Testthetopofthebarthereshouldbenomovementwhenthelatheisclampeddown

6Testthefrontofthebaragainensuringthatthereisnomovementwhenthelatheisclampeddown

Alignthetailstockbyusingadialtestindicatorintheheadstock

AligningtheTailstock

NowweneedtosetthetailstockinlinewiththeheadstockDothisbyputting thedial test indicator into theheadstockchuckandtestthetailstockboreAdjustthetailstocktowardsthefrontortothebackofthebeduntilthetestindicatorreadstrueandtighten theclampscrewsA slightdifference inverticalheightwillnotbetheendoftheworlditjustmeansthereisprobablysomeweartothebaseofthetailstockcastingbutthereshouldbenovariationfromfronttobackinthehorizontalalignmentPutalongbarbetweenthecentresandtakealightcutalong

it using a fine power feed Run along the bar a couple moretimes at the same setting to remove any push offWhen youmeasure thebar it shouldmeasure the sameatbothends Ifthe bar is larger at the tailstock end you need to reduce theheightofthebedatthefrontofthetailstockslightlyIfsmalleratthetailstockendyouneedtoreducetheshimatthebackofthe tailstockend Itprobablywonrsquotneedmuchadjustmentasslightadjustmentstotheshimoradjustersatthetailstockendwillsoonbringitintoline

Usingatestbartocheckforparallelturning

LubricatingtheLathe

You should follow the manufacturerrsquos recommendations forlubrication Usually this is thin oil for the headstock oftenhydraulicoilandslidewayoil forthemovingpartsLubricationshouldbedoneregularlyIfthelatheisfittedwithasightfeedoileritshouldshowoilinitAdjustablesightfeedoilersasusedonMyfordandsimilarlathesshouldbeadjustedsothattheoildripswhen the lathe is running but does not dripmuchwhenthe lathe is stopped The slight vibration when the motor isrunningisusuallyenoughtocausetheoiltodripToomuchoilisbetterthannotenoughoilisfarcheaperthannewbearings

Atypicaldrip-feedlubricator

UseanoilgunonalltheoilnipplesYoucangetaroundthetendencyfortheoiltogoeverywhereexceptintothenipplebyputtingapieceofwritingpaperoverthenippleandthenusingthe oil gun as normal The paper will stop the oil squirtingeverywhereThemandrelbackgearalsoneedstobelubricatedWheninusethemainbackgearisrunningontheoutsideofthelathemandrelandneedstobelubricatedoftenoritwillgethotandwearChangewheels should be lubricated with oil not grease If

youusegreaseswarfwillsticktothechangewheelsandcauseunnecessarywearTo stopswarf running through themandrelanddroppingoutontothechangewheelsputawinebottlecorkor similar into the left-hand end of the mandrel This willeffectivelystopanyswarfgettingthroughtothechangewheelsOil the saddle and cross slide and also the nipples on the

tailstock Make sure oil is showing at the edge of the slidingsurfaces A squirt of oil on the cross slide and topslide feedscrew bearing is needed as well Check the manufacturerrsquosinstructions for lubricating the rest of the lathe Follow themotormakerrsquosrecommendationforlubricatingthemotorTrytoavoidusingWD40onthelatheWhileitisanexcellent

lubricantwaterdisplacerittendstodiscolourthelathebed

Useabitofpaperundertheoilguntostoptheoilsquirtingeverywhere

AvoidingtheRustFairy

Rust canplayhavocwith a lathe quickly turning thebedandother parts into a brownmess Various sizes of plastic coverssuitable forcovering lathesareoftensold foruseasbarbecuecoversinDIYstoresAplasticlathecoverwillhelptokeeprustatbaybutmoreneeds tobedoneAbagcontainingsilicagelplacedundertheplasticcoverforexamplewillabsorbexcessmoisturesilicagelcanbeboughtverycheaplyoneBay

SilicageliseasilyobtainablefromeBay

Alternatively you can buy a vapour phase inhibitor forprotecting the lathe The vapour phase inhibitor chemical issuppliedonafeltpadinsideaplasticpotThechemicalformsaprotectivelayeroneverysurfaceBecauseitisavapouritwillfind its way into every cranny and is also used for protectingtools and accessories in tool cabinets and drawers It usuallylasts for twelvemonths ifenclosedby theplasticcoverSomemachinetooldealersareabletosellsuppliesofthisproductinsmall ready to use containers rather than in industrialquantitiesAlwayscleanthelathedownafteruseswarfwillsoonrustif

leftonalatheasitwillprobablybecleanfromturningandwillnotbeprotectedbyoilTheuseofanovencookingtrayunderthe lathe bedmakes it easy to remove swarf at the end of aturning session The tray also helps to retrieve a parted offcomponentora lost screw froma tipped turning toolAnotheralternativeistocoverthelathechiptraywithnewspaperwhenyouhave finished turning remove thenewspaper screw it upandthrowitawayWhenfittingachuckorfaceplatetothelathemakesureyou

cleanthemandrelthreadtheregisterandthefaceYoushouldalso clean the mating threads the bore and the face on thechuckorfaceplateYoucancleanthethreadandboreeasilybyusing two toothbrushes bolted back to back with spacers inbetween Make sure the Morse tapers in the headstock andtailstock are cleanbefore fitting aMorse taper accessory TheMorse taper to be fitted should be free from scratches burrsandbruisesIt is good idea tomake a chuck board for usewhen fitting

chucks to a lathe or removing them This is a piece of wood(plywood will do) that sits on the lathe bed while you arescrewingthechuckonandoffThechuckboardwillprotectthelathe ifyoudrop thechuck It canalsobeused toprotect thelathebedwhenyouarehacksawingorfilinginthelatheIf you keep your lathe clean and lubricate it regularly it

shouldlastalifetime

AlargetraywillcatchmuchoftheswarfandtheholeslettheoildrainawayUsenewspapertosoakuptheexcessoil

SAFETYINTHEWORKSHOP

RememberyouareresponsibleforyourownsafetySafetyisamajorconcernintheworkshopTherearecertain

thingsyoushoulddoandobviouslythingsyoushouldnotByitsverynatureaworkshopcanbeadangerousplaceallwecandoismakeitassafeaspossiblewhilestillallowingustoworkinit

WorkingAlone

Mostofyoureadingthisbookwillprobablybeworkingaloneinasmallworkshopgarageorgardenshed IfyougethurtyoumaypossiblybeonyourownAsapriorityIsuggestyoutakeamobilephoneintotheworkshopandkeepitinyourpocketTheability to contact your family a friend or the emergencyservicesquicklycouldsaveyour lifeKeepthephoneswitchedoff while in the workshop however as it is an unnecessarydistraction

FirstAid

FirstAid

AFirstAidboxwithcontentsisanecessityandshouldincludeaneye-bathandeyewashYoushouldparticularlylearnhowtostopbloodflowingThereareplentyofwebsitesthatwilltellyouhowtodothisCheckthemoutnowbeforeyougobackintotheworkshop

ElectricalSafety

Checkforearthcontinuitywhilethemachineisunpluggedwithavoltohmmeterfromtheearthpinonthethreepinplugtothemetalpartofthelathe(somepaintmayhavetoberemovedforareadingtotakeplace)Youshouldgetareadingofzeroohmsorabeep if themeterhasacontinuity rangeYoushouldalsobe sure that the electrical sockets on the wall are correctlyearthedIfindoubtconsultacompetentelectricianLightingandelectricheatingshouldbeonaseparatecircuit

tothemachinessoyouwillstillhavelightifthemachinestripoutPlugasmalllightintothemachinecircuitsoyouhavesomelight if the lighting circuit trips out When I go on holiday Ialwaysturnoffthefusetripsforthelightinginordertomakeitmore difficult for intruders to move about quickly Leave thehouse alarm and smoke detectors on (The house alarmmayactivateeighthoursafter theelectricity is turnedoffwhenthebatteryexpires)

Adigitalmultimeterisveryusefulinthehomeworkshop

BeAware

Bementally alert while using the lathe Avoid operations thatmightputyourhandsatriskofenteringthemovingpartsofthelathe Do not operate any lathe while under the influence ofdrugs alcohol or prescription medication that may causedrowsinessorotherwiseaffectyourability to control the lathesafelyDonotattempttoworkonalatheandtalkatthesametimeIfyouhavetotalktosomeoneswitchoffthelathebeforedoingso

KeepItClean

TheareaaroundalatheshouldbekeptfreeofobstructionsThefloorshouldbecleananddrywithanyoilorotherspillscleanedup immediately The lathe should be kept clean and tidyMachinedangerareasshouldbemarkedontheworkshopfloorand observed Workbenches placed near a lathe should be

strongandequippedwithanon-slipsafetysurfacetostoptoolsor other items rolling onto the floor a rubber car mat willsufficeA rubberdoormat on the floorwill allow swarf todropthrough in order to save you getting swarf embedded in thesolesofyourshoes

Asuitablefloormatwillallowswarftodropthroughandhelpkeepyourfeetwarminwinter

LearntoUsetheLathe

Donotuseany lathebeforeyouare familiarwith thecontrolsandareawareofthedifferentwaysofstoppingitThismaybea clutch an onoff switch a No Volts release switch or anemergency stop button I strongly advise fitting a No VoltsreleaseswitchifyourlathedoesnothaveoneAswellasbeingusefulforstoppingthelatheinanemergencyitwillpreventthelathefromstartingupbyitselfafterapowercutIfyouarenotcomfortableworkingwith electrical equipment get a qualifiedelectriciantofittheswitchforyou

StaywiththeLathe

Nevereverwalkawayevenforamomentwhilethelatheyouare using is switched on Switch it off if you are leaving itunattended and only leave the lathe after it has come to a

completestopNeverleavealatheinanunsafeconditionMakesure that you have not left the chuck key in the chuck Thechancesarethatifyouarehalfwaythroughsettingupthelathewhen you return you will forget what you have or have notdoneIfindoubtleaveabignoticeremindingyourselftocheckthatthelatheissafebeforecontinuing

Donotleavethechuckkeyinthechuck

SwitchOffwhenAdjustingtheLathe

Shut off the power supply to the motor before starting anyoperationsrequiringaccesstothelathesuchaschangingtoolsmeasuring work mounting or removing accessories changingspeed and setting up change gears The lathemust be safelystopped Just zeroing a variable-speed drive is not safelystoppingitusethezerovoltsswitchtoswitchthepoweroffaswell

CheckbeforeStartingtheLathe

AlwaysrotateyourworkpiecebyhandtomakesureitclearsthetoolrestsaddleandbedDoublechecktomakesureyourworkis securely clamped in the chuck or between centres beforestartingthelatheBecertainthattheworkpieceturnsfreelyand

isfirmlymountedThespeedofthelathemustbecheckedbeforeturningiton

When turning irregular shapes start the lathe on a low speedandincreasethespeedbyapulleystepeachtimeIfthelatheisbouncingabout lowerthespeedandorbalancethework Ifthe work vibrates stop the lathe and check the reason ThechancesarethatyouarerunningthelathetoofastMeasuringequipment toolingandworkpiecesshouldnotbe

leftona latheastheycanvibrateoff intomovingcomponentsand be thrown around the room Check for loose items on alathebeforeuse

UsetheLatheGuards

NewlatheswillbefittedwithguardsoverthemotorshaftdrivebeltandspindlepulleysTheseguardsshouldalwaysbeinplacebefore using the lathe Any other moving parts should beguardedtopreventanythingfallingontothemovingpartsAlthoughguardsareoften removedbymachinistsprovided

they are constructed from clearmaterials and open and closeeasily theyaddsafetywithout interferingwith theworkbeingdone Guards will at the same time deflect swarf and anycoolantthatisbeingusedGuardsfittedtothelatheshouldnotbe removed while it is in use They should be made fromsuitablematerialandnothavesharpedgesTheyshouldnotberemovedforadjustmentandlubricationofthelatheunlessthisis unavoidable Lathemanufacturers donrsquot usually supply chipguards soaddingoneshouldbeconsideredChipguardswithmagnetic bases are available although they can attract steelswarftothemagnetPutthebaseintoaplasticbagtoaidswarfremoval

UseEyeProtection

Lathes can throw sharp metal chips considerable distancesespecially at high cutting speeds Apart from deep cuts thechipsmay leave the tool red hot cause skin burns and even

burnholes in clothing Youmust use safety goggles or propersafetyspectacleswhileintheworkshopAlwayswearindustrialqualitysafetyglassesfittedwithsideshieldsSpectacleswithoutsafety lenses are not adequate eye protection When theglasses get dirty do not wipe them off as they will becomescratchedWashthemoffunderthetapinstead

TakeCarewhenRemovingSwarf

Do not attempt to remove chips or turnings with your handsAlwaysswitchoff the lathefirstandeitherpull theswarfawaywithalargemetalhookorliftitoffusingapairofglovesIftheswarf is tangled around the lathe untangle it with a pair ofpliersandnotaglovedhandasitwillcutstraightthroughtheglovesandintoyourhandUseadustpanandbrushtoremovesmall chips and swarf from the swarf tray ndash never use yourhandsWhenswarfbecomesstringyandbuildsuponthetoolortoolpostturnoffthelathebeforeremovingit

AvoidLooseClothing

IfyouarenotwearingoverallswearshortsleevedshirtsorrolllongshirtsleevesabovetheelbowsLoosesleevescancatchonrotatingworkandquicklypullyourhandorarmintothe latheObviously though keep your arms protected if hot swarf isflyingaroundSwarf can get inside protective clothing especially collars

(useaclothespegtokeepyourcollartight)pocketsandshoesTostopthesleevesofanoverallcatchingsewelastic intothecuffsorwrapacoupleofthickelasticbandsaroundthecuffstostopthesleevesgettingcaughtupUnder no circumstances wear a necktie when operating a

latheProtectiveglovesshouldneverbewornwhileoperatingalathe Protective gloves may be worn when swarf is beingremovedbuttheymustberemovedbeforeswitchingthelathebackon

UseSturdyFootwear

WearsteeltoecapsafetybootstheyarenotexpensiveandwillhelptoprotectyourfeetfrominjuryifyoudropaheavyobjectonthemThelsquotrainerrsquoversionisparticularlycomfortableDonotallow stringy swarf to fall on the floor as youwill get cuts onyouranklesandmayeventripoverit

AvoidJewellery

Do not wear wristwatches rings or jewellery when in theworkshop as it could catch on a rotating part of the lathe orworkpieceThisalsoapplieswhenmovingalatheintooroutoftheworkshopsincetheycouldcatchona falling lathe IfyourotherhalfcomplainsthatyouhavetakenoffyourweddingringexplainthatyouwouldnrsquotbeabletowearitagainifyourfingerismissingduetoanaccidentLonghairshouldbetiedbackasyoucouldbepulledintothelatheifitgetscaughtintherotatingwork

LiftingintheWorkshop

Back injuries can be caused by incorrect lifting practices It isimportant to bend your legs when lifting rather than bendingyour back A hoist or engine lift should be used to lift heavyitems A stool in theworkshopwill take the pressure off yourlegs and will provide a welcome break after you have beenstoodatthelatheforawhile

Self-ignitingMaterials

If you machine titanium or magnesium which can ignite andburn vigorously keep the accumulation of turnings to aminimum If thematerialdoescatch firedonrsquotusewaterorawater-based coolant as an extinguisher since it will makematters much worse Before starting to machine titanium ormagnesiumfillalargebucketwithdrysandcoveritandkeep

it by the lathe The sand will smother the flames veryeffectivelyYoucouldalsobuyoneofthespecialfireretardantsusedinindustryBeware also of grinding aluminium on the bench grinder

Aluminium and steel filings are the ingredients of Thermite apowerful explosive that can also burn If you grind aluminiumandthenchangeovertogrindingsteeltheredhotsparksareliable to set the steelaluminium mix on fire This is a verydangerous combination ofmaterials and should be avoided atallcosts

SafetywithBarStock

Bar stock should be contained within the headstock and notallowed to protrude from the rear of themandrel I once sawsomeone switchona lathewhenabrassbarwas stickingoutfrom the back of the headstock by about two feet With thelathe running at 2000rpm the bar whichwas aboutfrac34in (19mm) in diameter was bent at right angles and caused theheavy lathe which weighed 1280kg to jump about Luckilysomeone managed to switch the lathe off before any majordamageoccurredItwasnottheoperatorhehadrunwellawayandwasnowheretobeseen

SomeFinalWordsonSafety

Wherever possible the machine height should be adjusted tosuittheuserWearestillusingfifty-year-oldmachinesbutfiftyyearsagothenationwasshorterTheworkplaceshouldbeprovidedwithuniformlightingthat

gives an adequate level of illumination Individual machinelightsarebestThe lathemust be set to operate at the speeds and feeds

recommended for thespecificmetalbeingturned If themetalrotatestooslowlyortooquicklyorthefeed istooslowortoofastaccidentsarelikelytooccurThe area directly in front of and behind the workpiece is

known as the lsquofiring zonersquo or the lsquored zonersquo This is where apiece of work is likely to go as it leaves the lathe Make it ahabit to keep clear of this zone when you turn the lathe onLearnwhere theNoVolts switch is as youmightneed to turnthelatheoffquicklyByfollowingalltheaboveadviceyoushouldnowbeableto

worksafelyfullyawareofanysafetyproblemsthatmightariseAtthispointyounowknowhowtoinstallthelathelookafter

itclean itandmaintain it InChapter3wewill lookatcuttingtoolsandexaminehowtoselectcuttingspeedsandfeeds

Thisbarisstickingouttoofarfromthebackofthelathe

3CuttingToolPrinciplesFeedsandSpeeds

The first part of this chapter will look at the materials fromwhichcuttingtoolsaremadeaswellastheirbasicshapeandgeometryWewill thenconsider selectingsuitablespeedsandfeeds

MAINTYPESOFTURNINGTOOLS

There are three main types of turning tool used in modernworkshops HSS (high speed steel) tools carbide brazed-ontoolsandinsertedtiptoolsAllhavetheirusesintheworkshopandformost jobsthere isnopreferenceforonetypeovertheothersTherearealsocarbonsteeltoolbitsalthoughinpracticetheyarejustaboutobsoleteCarbonsteeltoolscanbemadeinthe homeworkshop but apart frombeing used tomake formtools(seeChapter11)thereaderisunlikelytousethismaterialfortools

Ageneral-purposeHSSturningtoolsuitableformildsteel

HSSTOOLS

HSStoolscanbepurchasedsinglyorinsetsalreadygroundtothecorrectshapeIt ischeaperhowevertopurchasethemassquare tool blanks in various sizes ready for you to grind toshapeThecompleteready-groundsetswillprobablycomewithseveralshapesincludedthatyouwillneveruseIfyoucanbuyafewready-groundtoolscheaplytheywillbeofuseasguidestoseehowtosharpenyourownHSStoolblanksHSS form tools from industry are often available second-

handTheseareespeciallygroundtomachineacomplex formall in one go You can often find some that are ground to asuitable shape to form the end of a threaded componentincludingtheundercut

HSSformturningtools

Brazed-onCarbideTools

Brazed-on carbide-tipped tools are quite useful especially forfacing and boring cast iron but they really need a diamond-facedgrindingwheeltokeepthemsharpCarbidetipsandtoolscomeinvarioussizesandhardnesstosuitindividualmaterialscarbidetoolsforsteelwilloftenbepaintedbluethoseforcastiron are painted red and those for stainless steel are paintedyellowThecolourindicatesthesuitabilityofthetoolforcertainmaterials

Brazed-oncarbide-tippedtoolscomeinvariousgradesshapesandsizes

InsertedTipTools

InsertedcarbidetiptoolsareveryusefulbuttheyarenotcheapThe tipsarenotusually sharpenedafterwearingout you justthrow the tip away and fit a new one Most modern carbide

inserts however do have more than one cutting facesometimestheyhavetwoandoccasionallyfourormorecuttingedgesareavailableYoucanevengetformturningtoolswheretheinsertisroundandcanberotatedafull360degrees

Theleft-handtoolisblueindicatingitisformildsteelwhiletheright-handtoolisredindicatingitisforturningcastiron

Some diamond-shaped tips can be used in different toolholders two edges are used in one tool holder and the othertwoedgesareusedinanothertoolholdersoyougettwicethelifepertipInserted tip tools are available for internal and external

screwcuttingwherethetipsareheldat thecorrecthelixangleofthethreadinthetoolholderThedrawbackisthecostofthetipsandeachsizeofthreadusuallyneedsitsownsizeoftip

Aninsertedtipcarbideturningtool

Carbidegroovingtools

InsertedtipgroovingtoolsareidealformachininggroovesforOrings and circlips Theyare available inmany standardwidthsandcanoftenbeusedasparting-offtoolsforsmallerdiametersOneof themostusefulgrooving tools forsmallersizegroovesandpartingoffistheMiniThinsystemassoldbyMSCIndustrialSupplyCo

TheMiniThintoolholderisidealforgroovingandalsoforpartingoffsmalldiametersTheshankissostrongcomparedwiththecutbeingtakenthatusinganoverhangasshownisquite

safe

Coatingstoreducetoolwear

Tipsarealsoavailablewith various coatings that improve toollifeThemostcommoncoatingistitaniumnitride(TiN)whichisgold in colour Other coatings that offer slightly better wearresistancearetitaniumcarbonnitride(TiCN)whichisbluegreyincolourandtitaniumaluminiumnitride(TiAlN)whichisvioletbronzeReady-groundHSScuttingtoolssuchasdrillstapsandreamers are also available with these coatings but once yousharpenthecutterthecoatingisgoneTipped toolsneedadeeper cut ahigher feedandahigher

speed than HSS tools Thismeans that the lathe needs to bestrongrigidandhaveamplepowertodrivethe lathemandrelwhen taking a heavy cut this rules out using tipped tools onlathessmallerthanabout2in(50mm)centreheightSmaller tools are made to fit the Unimat and similar small

lathesbutthesemachinesjustdonrsquothavethepowerneededtodrivethemAtbesttakingacutwillstopthelatheatworstthetoolwillchip

Insertedtiptypes

Inserted tip tools come in many shapes and sizes Some tipshapes and sizes are made to an international standard andothers are to the makerrsquos own standards Wherever possibleuse ISOstandardtoolsas thetipswillbe interchangeablewiththosefromothermanufacturersandwillprobablybecheaperaswell The ANSI system commonly used in the USA is notcompatiblewiththeISOsystemusedintherestoftheworldIfyour lathe ispowerfulenoughyoucantakeadvantageof

insertedtippartingoffbladesThesearemounted inaspecialtoolblockandthebladecanbeslidinoroutdependingonthediameteryouarepartingoffThebladecarriesan inserted tipspecially designed for parting off There are three types of tipavailablesquare-endedtipstipsthatareangledtotheleftand

tips that are angled to the right Square tips are used forgeneral parting off tips angled to the left are usedwhen youdonrsquotwanttoleaveapiponthebackendoftheworkandtipsangledtotherightareusedwhenyouwantacleanfaceonthefrontoftheworkThe parting off blade is oftenmounted upside down at the

backofthe lathecrossslideTheactionofpartingofftendstolift the whole cross slide slightly and forces the cross slidetightly into thematching dovetail whichmakes itmuchmorerigidIfthepartingofftooldigsinwhileinthebacktoolpostthetool tends to lift and push away from the work whereas in afronttoolpostthetooltendstodiginandpullintothework

Simplifieddiagramofpartingofftoolangles(A)straightpartingtool(B)angledtotheleft(C)angledtotheright

POWERREQUIREMENTS

Whenturningmildsteelorstainlesssteelwithanycarbidetoolthe machine horse power required is considerably more thanthat required forordinaryHSStoolsThe twomain reasons forthisarethatcarbidetoolsoftenhaveanegativerakeangleonthecuttingedgeasthistypeofedgelastsmuchlongerthanapositiveangle especially for intermittent cuts andbecause in

industrial use carbide tips are called on to remove largerquantitiesofmetalathigherspeedsandfeedsFor guidance on using tipped tools in the small workshop

wheretimeisnotasimportantasinanindustrialenvironmentIwould recommendusing twice the speedused fornormalHSStools and a fine feed of about 0002in (005mm) per rev as astarting point This can be adjusted up or downdepending ontheresultsThemaindifferencebetweenHSStoolsandcarbidetippedtools(eitherbrazed-onorinsertedtip)isthehorsepowerrequirementofthemachineinuse

Thispartingofftoolismountedatthebackofthelatheinaspecialbacktoolholder

SELECTINGTHECORRECTSPEEDSFORDIFFERENTMATERIALS

Overmanyyears through trialanderror cuttingspeedshavebeendeterminedthatgiveanoptimumtoollifebalancedwithadecent surface finish These speeds are normally quoted inlsquosurfacespeedinfeetperminutersquoSpeeds and feeds used on industrial machines where the

primary tools will have inserted tips will be a lot higher than

thoseusedinthesmallworkshopwhereHSStoolsarethenormThe accompanying table gives an idea of the speeds that

shouldbeused forvariouscommon typesofmaterial likely tobefoundintheworkshopThespeedslistedshouldbesuitableforbothturninganddrillinginthelatheForreaminguseabout25percentoftherecommendedspeedsThe table is a guide only and it is likely that the machine

speedsavailablewillnotbeexactlythoserequiredandyoumayhavetoresorttolsquonearenoughisgoodenoughrsquoSetthelathetothe nearest speed lower than indicated in the table for thediameterandmaterialbeingcutThiswillbefineforHSStoolsDouble the recommended HSS speed for carbide tools For

parting off use about 30 per cent of the recommended HSSspeed For form tools use about 50 per cent of therecommended speed for the initial cuts and then engage thecorresponding back gear (just switch to back gear leaving thebelts on the same pulley) and gently tap the handle until itreachesthefinishedsizeandallowittofinishthecutbyitselfYou may have to adjust the speed down if you get a lot ofchatter

Forturningcastironuseacarbide-tippedtoolrunningattheHSSspeedtoremovetheskinYoucanthenfinishtheturningwithaHSSsteeltoolifyouwishPlease remember if doing any work that might be

unbalancedstartoffslowlyandincreasethespeedabeltstepatatime

THEACTIONOFCUTTINGTOOLS

Basicallya lathe tool isawedge that is forced into theendofthe rotating bar to remove metal As long as the tool is fedforwardwhilethelatheisrotatingmaterialwillberemovedA typical right-hand turning tool has a cutting angle of 90

degreeslessthesideclearancelessthesiderakeThecuttingangle for this example is 90ndash10ndash10= 70 degrees This is theangle that is wedged into the work to remove the materialSoftermaterialswillhaveasmallercuttinganglewhilehardermaterials will have a larger cutting angle Tool angles varydependingonthetypeofmetalbeingturnedToolsforturningsofter metals usually have higher rake angles than thosedesigned for harder metals since a turning tool will normallyholditsedgeforlongerinsoftermaterialsBrassalthoughsoftusuallyhasnotoprakeonthetoolatallOther angles to be aware of are the top rake and the side

rake

CUTTINGTOOLSHAPES

The followingaresomeof thedifferent shapes thatyoumightfindusefulforgeneralturningandmetalremoval

Right-handknifeturningtoolAllrakeanglesare10degrees

Right-hand knife tool This is used for general turning andfacingofbarstockDependingontheworkyouaredoingyoumayfindaleft-handversionofthistooluseful

Typicalroughingtool

Right-handroughingtoolIthasaleadingangleandasmallradius on the tip of the tool This tool is used for fast metalremovalwherefinishisnottooimportantAgainyoumayfindaleft-handversionusefulAroughingtoolcuttingatanangletoabarwillremoveachip

widerandthinnerthanatoolcuttingat90degreestothebarThis improves tool life although you will have to square theturningupwithastandardknifetool

Typicaldouble-sidedroughingtool

Double-sided roughing tool It can turn towards the left orright It canalsobeusedasaplunge tool to removematerialfroma groove orwhere the component needs to be lsquowaistedrsquodown

Simplepartingofftool

Simple parting off tool This is suitable formostmaterialsYouwillprobablyneedalargeoneforpartingofflargediameterbarsaswellasasmalloneforpartingoffsmallcomponents

Internal(top)andexternal(bottom)screwcuttingtools

ScrewcuttingtoolThisisusedforcuttingscrewthreadsTheanglewilldependonthethreadyouarecutting60degreesformetric55degreesforWhitworthandBSFetc

Shallowboringtoolcapableoffacingacrossthebottomofahole

Boring and facing tool This toolrsquos unusual shape will befound very useful when recessing a large bore It will plungestraight intoasmalldrilledholeandwillalso face rightacrossthebottomoftherecess

Double-endedchamfertoolchamferingadiameter

Double-ended chamfering tool It has 45 degree angles atbothendssoitcanbeusedtochamferexternaldiametersandinternalbores

Double-endedchamfertoolchamferingabore

Othershapescanbeusefulbutthetoolsshownhereshouldbesufficienttogetyougoing

BORINGTOOLS

Boring tools are used to clean up a previously drilled holepossiblytomakeitruntruebutmorelikelytoensuretheholeistothecorrectsizeTheyarenormallylongerthanordinarytoolsandtendtostickoutfurtherfromthetoolholderHSStoolsaresuitableformostusesCarbideinsertedtipboringbarsarealsoreadilyavailableandarethebestbetforturningcastironinthesmallworkshop

HSSboringbar

For really small holes down to2or3mm indiameter solidHSSandcarbideboringbarsarereadilyavailableAlthoughtheyarenotcheaptheywillbefoundveryusefulandquicktouseAnothermethodofboringahole is tousea longseriesslot

drillasaboringtoolInuseclamptheshankinthetoolholderwiththepointatcentreheightmakingsuretherestoftheslotdrillisclearofthesideoftheboreYoucanthenrunitthroughtheboreinasimilarmannertoastandardboringbar

Asmallcarbideboringbarinsertedintoamildsteelshank

PARTINGOFFTOOLS

PartingofftoolsprovideaquickwayofcuttingoffworkfromtheparentbarThereisrarelyanyneedtoworryaboutcuttingthecomponentofftothecorrectlengthtogetagoodfinishAslongasthecomponentislongerthanrequireditcanbeputbackintothe chuck or a collet and the parted off face can be faced tolengthorotherwiseworkedonThepartingofftoolcuttingfacecaneitherbesquareoritcan

beangledtotheleftorright(seepage43)Thesideofthepartingofftoolcouldevenberadiusedsothat

it forms a radius on the end of the next component orchamferedtoformalead-inedgeforthenexttool

CUTTINGLUBRICANTS

Tomake cutting tools cut easily and to prolong their life it issometimesbesttouseacuttinglubricantForsteelIpreferneatcuttingoilItlubricatesbutisnotidealforcoolingtheworkIn industry coolant is normally used This is oil that has an

additivetomakeitsolubleinwaterMostsolubleoilswilldobutthe synthetic ones tend to sting your hands if you have anyopen cuts I would not recommend using soluble oils on thehome workshop lathe as I think they tend to wash thelubricating oil off the slideways and can encourage rustHowever this ismypersonalpreferenceandmanypeopleusesolubleoilinthehomeworkshopwithoutanyproblemsOil is suitable for use when cutting steels mild steels

stainlesssteelsandhighcarbonsteelssuchassilversteelThebestlubricantwhencuttingaluminiumisparaffinItstops

thealuminiumfrombuildinguponthecuttingtoolBrassandcast ironarenormallycutdryWhenturningcast

ironona lathe if the latheisfittedwithasolubleoiltankthecastirondustwillhaveanaffinityforthesolubleoilIfthelatheisthenusedonaluminiumthefreecarboninthecast ironcancontaminatethealuminiumwithblackstreaks

Inormallyplacetheoilorparaffininasmalldish(actuallyacatordogfoodbowl)andapply itbyhandwithasmallbrushThisdoesallIneedThenextchapterlooksatgrindinglathetools

4SharpeningToolsandHoldingThemintheLathe

ThenexttaskistogrindasetofusefullathetoolsThe first thing you will need is an off-hand grinder The

grindercanbeadangerousmachineso itshouldbeusedwithcare Eye protection must be worn the guards should becorrectlyfittedandtheremustbeadequateilluminationIdonrsquotlike using a grinder in a small workshop as the grinding dustflies everywhere and canget onto themachine slideways andtools generally making the workshop dusty and dirty Ifpossible set up thegrinder in a separate areaaway from theworkshopIhavemygrindermountedonafoodchoppingboardso I can carry it outside to use This has the addedbenefit ofdaylight although you are dependent on the weather or youmightneedtouseitafterdark

Theguardofthisoff-handgrinderhasbeenwidenedtoacceptarecessedwheel

GRINDINGWHEELS

IthasalwaysbeenstatedthatyoushouldnevergrindatoolonthesideofthegrindingwheelSofollowingthistheorywewillbeusingarecessedwheelwhereitswidthismuchthickerthanthepartofthewheelusedtoclampthewheeltothegrinderIstruggledtofindarecessedwheelof6in(150mm)diameterandfinally found a 60 grit grinding wheel on a personal visit toAxminster Power Tools in Devon (I could find only an 80 gritwheel in theircatalogue)Thewheels I like touse forgrindingare A60K5V if I can get them and I prefer the white wheelsdesigned for the harder tool steels rather than the grey orbrown wheels which are more suitable for softer mild steelsThedesignationbreaksdown like thisA stands foraluminiumoxide 60 is the grit size K is the hardness (I J and K beingmediumhard)5 is thestructure(thespacebetweengrainsofgrit) and V is for vitrified the method of bonding the grainstogetherTheKandthe5canvaryabiteitherwayandthegrit

shouldbe4660or80with60beingpreferredThe80gritisabitfineandwillclogupquitequicklySo-called green grit wheels made from silicon carbide are

available for sharpening carbide tools They are usually softerthanaluminiumoxidewheelsinordertoallowthegrittobreakdownbeforethewheelbecomesglazedfromgrindingthemuchhardercarbide

Witharecessedwheelyoucancutontheouterfaceoftherecessedsideofthewheel

TestingtheWheel

The first thingyoushoulddowhenbuyingawheel is tomakesurethat it is ratedatasufficientlyhighspeedfor thegrinderon which it is to be used Off-hand grinders usually run ataround2900rpmsoyouwillneedawheelratedtoatleastthatspeed it is all the better if the grinding wheel is rated at ahigher speed than the grinder Care should be taken whenhandlinggrindingwheelsastheyarequitefragileifknockedordropped A grinding wheel should only be purchased from areputableengineeringsupplierSupportyourgrindingwheelona piece of wood and tap the wheel gently with a plasticscrewdriver handle or similar The wheel should lsquoringrsquo if itsoundsdullitshouldbebrokeninhalfandeitherthrownawayorusedontheworkbenchasasharpeningstoneNeverthrowawheelawaywithoutbreaking it into twoyouneverknowwho

mightgettheirhandsonit

Thistoolrestwasdesignedtosharpenplaneironsandchiselsbutitisfineforlathetools

Amoderndigitalanglegaugeisidealforsettingthetoolrest

MountingtheWheel

The wheelrsquos bore should be the same as the spindle of thegrindingwheelOften theborewillbe largerandyouwill then

need some plastic spacers to reduce it Spacers should bereadilyavailable fromyour localengineeringsupplierYoucanturn thespacers fromplastic if youcanrsquotbuyany ready-madeonesAt each side of the wheel you should fit a paper washer

thesearemadeofblottingpapertypematerialandwillprobablyhave been supplied already stuck on the wheel The grindershould have twometal flanges one to fit at each side of thewheel Both flanges should be the same diameter These willhold the wheel true and spread the tightening load on thewheelThegrinderwillhavetwodifferent threadsontheendsof its spindle The right-hand side of the grinder will have aright-hand thread and the left-hand side will have a left-handthreadThedifferentthreadsaretostoptheclampingnutsfromunscrewingwhenthegrinderisrunningTofitthewheelremovetheguardandundothenutRemove

the metal flange and then the wheel Make sure the flangesdonrsquothaveany remainsof theoldpaperwasheron themPutthenewwheelontothegrinderspindle(rememberthespacerthepaperwashersandtheflangesateitherside)andscrewthenuthand-tightFinallyholdthewheelgentlyandgivethenutapinchupwithaspannerYoudonrsquotneedtoover-tightenthenutjustsufficiently tostop thewheel fromcoming looseRefit theguard and spin thewheel by hand to ensure it is not rubbinganywhereNowwearealmost ready to switch thegrinder onBeforedoingsohoweverputonyoureyeprotectionandstandtoonesideofthegrindersoyouarenotinlinewiththewheelshould it burst Then switch the grinder on All should be fineandthewheelshouldberotatingsafely

TOOLREST

Theworkrestsuppliedwithanoff-handgrinderisusuallyjustabitofbentsheetmetalboltedonItisusablebutonlyjustI recently purchased a ready-made tool rest as a basis for

makinganimprovedgrindingrestThiswasoriginallydesigned

forsharpeningplanebladesandchiselsforwoodworkingbutitmakes an ideal rest for sharpening lathe tools It is made ofaluminiumandisfullyadjustableforangleThebestmethodofsetting the rest to the correct angle is to use a digital anglegauge These are now very cheap and are readily obtainableThepositionoftherestinrelationtothegrindingwheelcanbeadjusted on its sliding base Many designs for tool rests havebeenpublishedandyoucouldmakeoneofthoseinsteadifyouwishtosavemoneyThetoolclampassupplied isdesignedtoclampplane irons

andchiselssothisneedstobechangedLathetoolsneedtobepresented to the grinding wheel at the correct angles If youdonrsquot have a digital angle gauge this can be achieved usingsimpleguidesmadefromanglesheetmetalandsomescrewsIused gauge plate made from a high carbon steel with anaccurategroundfinishthatcanbehardenedandtemperedbutmild steel would be perfectly suitable if you donrsquot have anygaugeplateavailableYouwillfindaprotractorusefulyoucangetasteelonewith

an adjustable blade for a reasonable price The protractorwillbeusedtosetthetoolanglethatisgroundonthetools

Sheetmetalprotractorsareavailableverycheaply

LATHETOOLGEOMETRY

LathetoolsneedtobegroundtocertainanglesbuttheanglesdonrsquothavetobeexactFormosttoolssomewherehandywilldounless you are grinding a form tool to a particularly accurateshapeIthasbeennormalforbookstoshowtheanglesontoolsas used in a production environment where tools will ideallyhavealonglifeoftenthislifeiscalculatedaslastinganeight-hourshiftsothetoolonlyhastobesharpenedandresetonceadayInthehomeworkshopwecan increasethesecuttingangles

andgetbettercuttingattheslightexpenseofshortertoollifeWehavealreadyexplainedtheshapesof the tools thatyou

willfindmostusefulToolanglesareknownbytechnicaltermstop rake front rakeside rakeandback rakeThe rakeanglesvary depending on thematerial to bemachined but a set ofstandardtoolswillgetyoustartedSomeoftheaccompanyingphotographsareactuallyoflarge-scalewoodenmodels

Theleft-handtoolissuitableforbothfacingandturningtheright-handtoolissuitableforturningonly

Left-handsideofthefacingandturningtoolshowingthefrontandtoprake

Topofthefacingandturningtoolshowingthefrontandsiderelief

Left-handsideoftheturningtoolshowingthefrontclearanceandthetoprake

Topoftheturningtoolshowingthefrontandsideclearanceandthetoprake

GRINDINGATOOL

WhengrindingHSStoolstrytokeepthemascoolaspossibleIfan HSS tool becomes too hot and is then quenched in waterminutecrackswillformonthecuttingedgesThesecrackswillmakethetoolcuttingedgebreakdownveryquicklywhenusedThe best practice is to grind a little bit off the tool and thenquenchitwhileslightlywarmDonotletthetoolgethotdipitin thewater little andoften This should ensure the tool edgedoesnotbreakdowninuse

GrindingYourFirstTool

Most angles can be ground by using the tilting table whileothersmayneedtobefixedinrelationtotheperipheryofthegrindingwheelThefrontandsideofthetoolcanbegroundbytippingthetableatthecorrectanglewhereasthetoprakecanbegroundontheperipheryofthewheelThegrinder should first be switchedoff andunplugged Set

thetoolresttotherequiredangleusingthedigitalanglegaugeoranangletemplateandtightenuptherestBefore switching on the grinder ensure that everything is

freetorotatebyspinningthegrindingwheelbyhandIf all is well put on your safety glasses and switch on the

grinderPlacethetoolonthetoolrestupagainstthesideoftheprotractor Slide the tool along the table until it reaches thegrindingwheel andmetal starts to be removed Slide the toolbackwards and forwards slowly along the restwhile putting alittle light pressure on the tool so that it continues to pressagainst the grinding wheel When you have removed a smallamountofmaterialcoolthetoolbitdownAtnotimeallowthetool bit to get hot Continue grinding until you have removedsufficientmaterialfromthetoolbit

Thegrindingrestissettothecorrectangleof10degreestogrindtheendofthetool

Grindingthefirstangle

TurnthetooltotheotherangleanddothesamesothatnowboththefrontandsideclearanceangleshavebeengroundThis toolwill be enough for brass but for steelwe need to

grindthetoprakeWhengrindingthetoprakeonaright-handtool the slide rest needs to be higher than the centre of thegrinding wheel so that it grinds the tool at approximately 10degrees

Thefirstanglehasbeenground

You have now ground your first lathe tool The tool asreceivedfromthegrinderwillbetooroughtousehoweversoyouwillneedtohonethecuttingedgesYoucandothisonanoilstone(usedwithfineoillike3in1)orwithadiamondlaporusing a combination of the two Lightly lap the front and sideclearanceanglesuntilyougetagoodfinishand lightlyhoneaverysmallradiusonthetipofthetoolFinallyhonethetoprakeangleandyourtoolisreadyforuse

Grindingthesecondangle

Thesecondanglehasbeenground

AllofyourHSSturningtoolscanbedoneinthiswayOnlytheangleswillvaryandthesecanbesetusingadigitalanglegaugeandprotractorAnoccasionalhonewillresharpenyourtoolsaslongasyoutreatthemwithcareA similar range of HSS tools and a parting off tool all with

zero top rake shouldbeavailable if youwill be turningbrassUnless you are doing quantity production one tool holdershouldbesufficientforbrassAsatoolforbrasshasnotoprakeandyouwouldnotnormallygrindthetopawayaslongasyoubuy tool steel of the same size the tip height will remain thesameYoucanthenusethedifferenttoolsinoneholderwithouthavingtoresettheheight

MACHININGCASTIRON

Carbide-tippedtoolsareidealformachiningcastironAsimplebrazedupcrankedtoolwithasmallchamferonthenosewilldoforbothturningandfacingcastironcomponentsThemainuseof this tool will however probably be truing up the faceplatethat comes with the lathe The large diameter combined withtheintermittentcutovertheboltgrooveswoulddestroyanHSStoolinafewsecondsAsmalltippedboringbarwillbeidealfor

taskslikeboringcastironcylinders

Grindingthethirdangle

Asimplediamondlap

Thethirdanglehasbeenground

Tosharpentippedtoolsyouneedadiamondwheelorifyouwant to remove large amounts of carbide a silicon carbidewheeloftencalledagreengritwheelowingtoitsusualcolourSilicon carbide wheels are much softer than aluminium oxidewheels as they need to break down faster to present newsharpergrainstothecarbidetoolAdiamondwheelisonlydesignedtolightlylapatippedtool

itisnotsuitableforremovinglargeamountsofcarbide

Diamondcupwheel

TOOLHOLDING

Smallerlathessuchasarefoundinmostworkshopsmayhaveatopslidewithatoolclampforindividualtoolsablockwithasingle slot to take the tool a four-way turret (or sometimes athree-way)oraquick-changetoolblockandholdersetThereisalsotheso-calledAmericantoolpostwhichisaroundbarwitha slot through it and a bolt in the top to clamp the tool ItusuallycomeswithmatchingdishedwasherstoadjustthetoolheightThistypeisnolongerverycommononlathes

Quick-changeToolPost

Themostversatiletoolholdingsystemisthequick-changetoolblockwithmatchingholdersThedrawbackwiththissystemisthe cost of extra tool holders you need quite a few one foreachtoolThequick-changetoolblockmountsonthefrontofthelathe

normallyontopofthetopslide(Blockscanbefitteddirectlyon

thecrossslidebytheuseofaraisingblocktoaidrigidity)

Quick-changetoolblock

Each holder is set up with its own particular tool The toolholderscanbe individuallysetso that the turning tool isdeadoncentreheightandispresentedcorrectlytotheworkpiece

Quick-changetoolholder

Quick-change tool holders are available with a straight cutslottotakestandardsquareshanktoolholderswithastraightcutwiththeadditionofaVeecut-outinthebottomforusewithroundtoolssuchasboringbarsandasafrontpartingoff tool

holdertotakeahighspeedsteelpartingoffbladeRearpartingoff tool holders are available to take an inverted parting offbladeeitherahighspeedsteelbladeoran insertedtipbladeLeft-handed and right-handed extended tool holders are alsoavailableandmayoccasionallybequiteusefulThetoolblock isnormallymountedonthetopslidebutyou

cangetraisingblockstouseinsteadofthetopslideThismakesthetoolholderblockmuchmorerigidAbackquick-changetoolblockwillneedmountingonaraisingblock

Backofaquick-changetoolholdershowingthedovetailtypeofmounting

Right-handandleft-handextendedtoolholders

StandardtoolholderwithaVeetotakeroundtoolholders

Frontpartingofftoolholder

ToolClamp

Satisfactoryworkcanbedonewithatoolclampedontothetopslideusingshimsteel toset thecentreheightof the toolThemaindrawbacksarethatyoulosethepositionofthetoolwhenyoutakeitoffthetopslidetofitthenexttoolandyoualsolosetheaccuratecentreheightofthetoolunlessyoukeepthetoolandshimstogetherIfyouaremakingonlyonecomponentthisisnotaproblembutitisanuisanceifyouaremakingabatchofmatchingcomponents

Simpletoolclamp

Single-slotBlockToolPost

AblocktoolpostisoftensuppliedwiththecheaperlathesThetoolpostisliterallyablockofmetalwithaslotcutinittotakethe turning tool It is relatively easy to set the tool up at thecorrectcentreheightbyusingvariousthicknessesofshimThisisfineforthebeginnertoturningwhoisjuststartingoutbutitisbesttoreplaceitwithafour-waytoolpostoraquick-changetool post You could of coursemake several block tool postsandkeepeachonesetwithadifferenttool

Four-waytoolpost

Backtoolpost

Four-wayToolPost

Four-wayToolPost

Thefour-waytoolpost isagoodcompromiseona latheasyoucansetfourtoolsintheturretandrotateeachoneintopositionas needed This speeds up production and is a lot faster thanusingasimpletoolclampThedrawback isthatthetoolsstickoutof the turret fourdifferentwaysandyoumightcatchyourhandonasharp toolAsimple ratchetstopensures thateachtool repeats its position when the tool post is rotated so theworkisaccuratelyturnedeachtimethetoolisusedAduplicatefour-waytoolpostwithtoolsforbrasswillspeedupproductionevenmoreCastingsareavailabletomakeyourownthree-waytoolpost The three-way toolposthas theadvantageofbeingable to get close to the work when you are turning betweencentresFor the front tool post I would recommend right-hand and

left-hand roughing tools right-hand and left-hand finishingtools a tool groundup to face barswhile using a half centreand a Mini Thin inserted tip grooving tool with grooving andparting off inserts You will also need large and small boringbarsbothHSSandwithinsertedtipsTheHSStoolsshouldbegroundupforuseasgeneral-purposeturningtoolsformildsteelandsimilarmaterialsThecarbideinsertedtipboringbarshouldbefineforcastiron

BackToolPost

You can fit a quick-change tool block to theback of the crossslideaswellasthefrontSpecialholdersareavailabletotakeaHSSparting off blade or an inserted tip parting off blade Thebladewill be angleddown to give top clearancewhenpartingoffTheseback-mountedtoolblocksareveryhandyastheycanalsobefittedintotoolholderswithafacingtoolorachamferingtoolFor a back tool holder set-up I would recommend an HSS

partingoffbladeafacingtoolforcastironandadouble-ended45-degree chamfering tool that can be mounted parallel with

the chuck or at 90 degrees to it This set-upwill allow you tofaceaworkpiecechamfertheoutsidediameterandortheboreandpartitofftolengthThenextchapterlooksatholdingworkinachuck

5WorkholdingintheChuck

This chapter covers the different types of chucks how to usethemandsetupworkinthemaccurately

Aself-centringthree-jawchuckfittedwithlsquodrilljawsrsquoNotetheexternaljawswhichareinterchangeablewiththedrilljaws

USINGCHUCKS

Themostusefultoolsforworkholdinginthelathearethree-andfour-jaw chucks The three-jaw chuck is usually of the self-centringvarietythistypeofchuckcomesasstandardwithtwosets of jaws The first set of jaws are known as inside or drilljaws as they are most useful for holding round and hexagonbarsTheother setof jawsareoutside jawswhichholdworkusuallyindiscformontheoutsideSelf-centringmeansthatwhenyouinsertabitofbarintothe

chuck and turn the chuck key the chuck centralizes theworkpieceas it tightensup It isunlikely to runperfectly truebutitshouldruntruewithin3or4thouYou can also purchase soft jawswhich are exactly as their

namesuggestsYoucan thenbore themout to fit thework Ifyouborethemonthelatheyouaregoingtousethemontheworkwillrundeadtrue

Asetofsoftjawscanbeturnedorboredtosuittheworktobeheld

Aself-centringfour-jawchuckThesealsocomewithexternaljawsandsoftjawsareusuallyavailable

Self-centring four-jaw chucks can be used for square barsTheyarealsousefulforholdingroundbarswithmoregripthanathree-jawself-centringchuckSoft jawsarealsoavailableforfour-jawself-centringchucks

Afour-jawindependentchuck

Youare howevermuchmore likely to comeacross a four-jaw independent chuck than a four-jaw self-centring chuckIndependent means that the jaws can be moved individuallyand the jaws can also be reversed one two three or four ofthemdependingontheworktobedone

Abaseplatecastinginafour-jawindependentchuck

Wewillfirstlookatthethree-jawchuckThebestmethodofmaking a component in one of these is if possible to turn itcompletely at one set-up If you put a piece of bar into thechuck face the end centre drill drill and ream it skim thediameterandpartitoffitshouldbeconcentricalloverThisisbecausewehaveturneditallatthesamesettingwithouttakingit out of the chuck If we need to machine the other endhoweverwhenwe turn it roundandput it back in the chuckthechancesareitwillnotruntrueThis iswherethe four-jaw independentchuckcomes inYou

canput thecomponent intoa four-jawchuckandset it to runtrueusingthedialtestindicatorAnyworkyoudoonthepartedoff end should then be concentric with the rest of thecomponentWhensettingworkinafour-jawindependentchuckfor a second operation use some thin shimbetween the jawsandtheworkpiecetoavoidmarkingtheworkWorkisoftenheldinafour-jawchuckbecauseitisacasting

anoddshapeorsquareandsowonrsquotfitintoathree-jawchuckIf thework just requires tobe faced flat rightacross the facethereisnoneedtosettheworkrunningradiallytrueItshouldbe near enough on the centre line as long as the work is

reasonablybalancedYou could of course put the component into a three-jaw

chuckbyfittingsoft jawsandmachiningorboringthemouttotake the component This is the best option ifmaking severalcomponentsthatneedtobeidenticalbutifyouonlyneedoneor two components a four-jaw independent chuck will be thequickestmethodofmachiningthemLargerdiameterscanbeheld ina three-jawchuckbyusing

theoutsidejawsThesehavealargeradiusontheinsideofthejaw ifthisradiusis largerthantheworkpiecethejawsshouldnot tend to dig into the work and mark it Outside jaws areuseful forholding components like small flywheels locomotivewheels and chuck backplates when machining the bores ofholesorwhenmachiningacrossthefaceWhenmachining thindiscs it isuseful toputsomepacking

behindthedisctomakeitstandproudofthejawsTostopthepackingflyingoutwhenthemachineisrunningmakeasetofthree or four packing pieceswith grooves at each end and fittensionspringstothemTheyshouldallbethesamediametersothatthebackoftheworkisparalleltothechuckThelengthand grooves can vary slightly as they donrsquot affect theparallelismTheyarequickandsimpletomakesoacoupleofsets of different diameters should find their way intoeverybodyrsquostoolbox

AlthoughmostlathechuckkeyshavesquareendstheyareoftenofdifferentsizesKeepeachkeywithitsownchuck

ChuckKeys

I have alreadymentioned that the chuck key should never beleftinthechuckwhenitisunattended(seeChapter2)PutthekeyintothechuckuseitandputitsafelyawayassoonasyouhavefinishedwithitIfyouswitchonthelathewiththekeystillinthechuckyoumightneedatriptothehospitalDonotuseexcessive forcewhenyou tightenup the chuck

Do not use a piece of tube a spanner or anything else as alever thechuckkeyon itsownshouldbesufficient to tightenthechuckontotheworkWhenusinga four-jawchuckasmallchuckkey littlemore

thanaknurledknobwithasquareoncanbeusedtoadjustthejawsinandoutpriortotighteningupwiththeproperchuckkeyThiswill save timeover adjusting the jawswith a large chuckkeyTo turn the independent four-jaw chuck jaws round a

carpenterrsquosbracewithapieceofsquarebarinittofitthechuckwillmakeshortworkofreversingthe jawsbutdonrsquotuse it forthefinaltighteningasitisliabletostrainthejaws

STARTINGTOTURN

Before going any further you need to learn how to do basicturningFor thisyouneed toput the three-jawchuckonto themandrelStartbycleaningthemandrelwithacleanbitofragorsimilar(Ikeeparollofpaperkitchentowellingintheworkshop)Nowyouneed toclean thechuckrsquosboreand threadusing thetwotoothbrushmethod(seeChapter2)BoththemandrelandthechuckshouldbecleanbeforeyouattempttofitthechucktothelatheSelecting and grinding turning tools has already been

discussed (see Chapter 4) so by now you should have acorrectlygroundturningtoolsuitableforroughingoutapieceofsteelbar

Barwithapiptoolaboveorbelowcentreheight

MakingaToolCentreHeightSettingGauge

Thistoolneeds itscuttingedgesettothecentreheightofthelatheThereareseveralwaystodothisbutoneoftheeasiestiswith a home-made height gaugeWhen starting out this is achickenandeggsituationyouneedtomakethegaugetosettheheightbutyoualsoneedatoolsetatthecorrectheighttomakethegaugeThesimplestwaytoovercomethisproblemistosetthelathe

tooltotheapproximatecentreheightandtakeacutacrossthefaceofthebarDependingonwhetherthereisapipremainingon theendof thebaryoushouldgetan ideahow farout thetoolheightisIfthereisnopipthismeansthetoolisoncorrectcentre height or too high A pipmeans the tool is too lowOfcourse you may have been lucky so try dropping the toolslightly until a pip remains You can then raise the tool a fewthouatatimeuntilthepipdisappearsThetoolshouldthenbeoncentreheight

Barwithnopiptooloncentre

Nowthatthetoolisatcentreheightyoucanmakeasimpleheight gauge Turn a piece of bar down to as close to frac12in(12mm)asyoucangetandleaveitinthelathechuckMeasurefromthetopofthecrossslidetothetopofthebarwithacheapheightgaugeLowertheheightgaugebyhalfthebardiameterTheheight

gaugeshouldbeexactlyonthelathecentrelineMakeanoteofthisdimensionWe now need to look at how to turn a bit of bar to an

accuratediameterWhenturningabartosayfrac12in(12mm)youneedtostartwithsomethingslightlylargerInthiscasethiswillbe⅝in(16mm)diametermaterialasthisisastandardsizeCutapieceofmaterialabout2in(50mm)longandputitinto

thechuckwithabout1in(25mm)stickingoutSkimtheoutsidedown to about 0510 thou or 1225mm which is 10 thou(025mm) above the size required (You should be aware thatmosthobbylathedialsremovetwicewhattheysayaonethoudivisionforexamplewillusuallytake2thoufromthediameterLargercommercial lathesaremuchmore likelytotakeoffonethoupergraduation)Nowtakesmallcutsuntilalmosttosizeusingpowerfeedif

you have it andmaking sure you knock the feed off before ithitsthechuckStopthelatheandwindthecarriagetothestart

of the bar Take another cut at the same setting andmake anoteofthediameterTakeanothershallowcutbutthistimegoonly about frac14in (6mm) along the bar knock the feed off andturn the lathe off Move the carriage towards the tailstock sothat you can measure the bar Continue making this cut andmeasureuntilthesizeiscorrectThenrunthetoolalongthefulllengthof the jobWindthecarriagebacktowardsthetailstockand take a finishing cut or two at the same setting ThediametershouldnowbetheexactsizerequiredIt is not difficult to turn accurately it just takes a little

patienceandpracticeThemoreturningyoudotheeasieryouwill find it is to hold accurate limits If you turn everythingaccuratelywhetheritneedstobeaccurateornotyouwillsoonlearntoturnwithinathouorsowithoutanyproblems

Measuringtheheightofthebarabovethecrossslide

Now we need to make a tool height setting gauge Cut alengthofbarjustoverthedimensionsyouwrotedownandfaceone end turn it round in the chuck and face the other endMeasurethelengthandfindouthowmuchyouhavetotakeoffit to give the dimension you want Put the bar back into thechuck and bring the tool up to the face of the bar Lock thecrossslideFacethebartolengthbyusingthetopslideindexmovingforwardsafewthouatatimeuntiltherequiredlength

is reached Younowhavea tool height settinggauge suitableforthefrontandreartoolsIf you have an inverted Vee bed lathe or if for any reason

youcanrsquotusetheheightgaugeflatonthebedyoucanputtheheightgaugeonaplateon topof the lathebedwhileyouaresettingthetoolheight

Settingtheheightgaugetothelathecentreheight

Settingtheheightofthetool

Usingthesettinggaugetosettheheightofthereartool

TurningtoaSpecificLengthandDiameter

Nowwewill turnabarwithastepon theendToensure thatthestep isthecorrect lengthwewilluseabedstopThiscanbe as simple as a block clamped to the lathe bed to stop thecarriage moving any further I use a simple home-made bedstopthatdoesallIrequireSetthebedstopthenmovethecarriageuntilittouchesthe

stop and lock it Wind the top slide so that the tool is justtouching the end of the bar and lock the carriage For thisexercise we will make the step 16mm long and 12mm indiameterWindthetopslidealong159mmWecannowroughout thestepateachendTurn theenddown toabout02mmabove the finisheddiameterbywinding thecarriagebackandforthYoucanusethe fine feedbutmakesureyouknockthefeed off before the carriage reaches the stop and finish up tothestopbyhandWindthetopslidealongtheremaining01mmto12mmandfinishthediametertosizeandlengthtakinglightcuts as previously Donrsquot forget to clean up the face of theshoulderyouhavejustturnedIfyouneedtouseabedstopatthetailstockendofthelathe

asimplemethodofdoingthisistouseabarplacedonthelathe

bed against the tailstock The bar acts as a stop when thecarriageiswoundbacktowardsthetailstockThistailstockendbed stop is useful when you are turning a groove in acomponentandyouneedstopssetatboth theheadstockandtailstockendsofthelathe

Ahome-madebedstop

TurningWorkontheOutsideoftheInsideJaws

Theoutsideoftheinside(drill)jawsareusefulforturninglargerdiameterwork that is too large to fit inside thedrill jawsThiswillmostoftenbe in the formofa flywheelcastingFlywheelswithsixspokesareidealforturninginathree-jawchuckasthespokes can fit between the chuck jaws Ideally you need totighten up the flywheel until it is tight but not so tight as todistorttherim

TurningasteponabarusingthestopThebarisheldinthethree-jawchuckandsupportedwiththetailstockcentre

Ausefultailstockendbackstopmethod

Holdingaflywheelinathree-jawchuck

Holdingaflywheelintheoutsidejaws

To ensure concentricity you should do as much work aspossibleonthecastingatthesametimeYoushouldbeabletoturntheoutsiderimofthecastingfacetherimfacethebossand drill bore and ream for the crankshaft all at the samesettingAllyouneedtodothenistofittheoutsidejawsreversethecastinginthechucktapitgentlybackontothestepsoftheoutsidejawsandfaceacrossthesecondsideoftherimandthehubUseabitofshimtoprotecttheflywheeldiameterItdoesnotmatter if the flywheel runs exactly true or not as you areonlyfacingitparallelandtowidthnotturninganydiametersto

size

UsingtheSoftJaws

Soft jaws are very useful when a component has to run deadtrue in the jaws for example when making something like agrindingspindlewhereconcentricityisimportantSoftjawslikelytobefoundinthehomeworkshoparesimple

rectangles of steel with the scroll and groove formed directlyintothesoftjawsAnothertypeofjawyoumaycomeacrosshasa grooved pattern in the main jaws that matches a similarpattern in theactualsoft jawsThesoft topsof these jawsareusually interchangeable They are more likely to be found onlarger chucks but you could make your own version for thesmallersizesofchuckifyouwishThemain use of soft jaws is for second operationwork for

examplewhenyouhaveturnedacomponentcomplete fromabitofbarandparteditoffNowyouneedtoholdthecomponenttruetofinishoffthesecondendYoucandothisbyboringoutthechuckjawstotheexactdiameteroftheworkpieceToborethesoft jawstheyshouldbetightened inthesame

direction as they will be tightened in use so that they areoperatingonthesamepartofthechuckscrolleverytimeIfyouhaveathincomponenttomachinefitthesoftjawstothechuckandtightenthejawsontoabitofbarheldinthechuckBesureto leaveenoughspace in frontof thebarsoyoucanbore thejawstofitthework

BoringsoftjawstofittheworkThejawsareclosedontoanoddmentofbartoturntheshallowregistersothatittakesthework

AlwaysusethesamechuckkeyholewhentighteningupthejawsThisappliestoanythingyoudowithaself-centringchuckStampacrossoracentrepopmarkagainstoneof the jaws IsuggestdoingthisnexttojawNo1butanyonewilldoaslongas you always use the samemarked hole Youmight as wellmarkallyourself-centringchucksinthesamemannerCarefullyborethejawstotheexactdiameteroftheworkto

be machined Try to get it exactly on size Undo the jawsslightly remove the bar and replace it with the workpiecewhichshouldnowrundeadtrueAusefulmodificationtothesoftjawsistodrillandtapahole

inthemiddleofthejawsandfitanAllenscrewtoeachholeIfyouwant toholda longbar in thesoft jaws it isnoweasy toboreallthewaythroughthejawsratherthanjustboringastepor part way through All you need to do now is find a disc ofmaterial to put into the chuck ensuring there is sufficientmaterialleftontheinsideedgesofthechuckjawstoborerightthroughtotakethebar

Holdthedisconthescrewheads ifnecessarydrillthediscbeforeboringBorerightthroughthediscandthejawsuntilyouarenearlytosizeatwhichpointyoucanborethroughthediscand test the resultingborewith theworkpieceMakesureyouclean the bore thoroughly before trying the workpiece sinceloose dust can make the hole seem smaller than it really isWhentheworkpieceenterstheborefinishboringrightthroughthe jawsgo througha coupleof timesat the samesetting totakeoutanyspringintheboringbarYoucannowremovethedisc clean the jaws and put the workpiece right through thechuckcheckingthatitrunsdeadtrueThisoperationmaysoundtimeconsumingforasingle item

but if you have several components to make it will save aconsiderable time on setting up each bar individually to runtrue

BoringsoftjawsusingaringThesoftjawshavethreeAllenscrewsthatarecloseddownontotheringwhileboring

TurningtheoutsideofthesoftjawsusingaringThesoftjawshavethreeAllenscrewsthatareopenedupontotheringwhileturning

NowthescrewsareinplacewecanworktheotherwayroundandholdcomponentsontheoutsideofthejawsTodothisyouwillneedaringofasuitablesizeontowhichyoucantightenthejawswith the jaw loading acting outwards so any componentyouputontheoutsideofthejawswillberunningconcentricallyThiswill be ideal for itemssuchas tractionenginewheel rimsandotherlargehollowortubularworkpiecesOne other use for soft jaws is to hold irregular-shaped

components Put a piece of bar into the soft jaws and bore aholeofanysizeand thencleanup theboreso thatallof thejawsare true Transfer the chuck to themillingmachine tableandclampitdownUseatestindicatortocheckthattheholeinthechuckistrueYou can now mill a nest to take any irregularly shaped

component confident that when the chuck is returned to thelatheitwillberunningtrue

Plungertypedialtestindicator

Levertypedialtestindicator

DialTestIndicators

Therearetwomaintypesofdialtestindicatortheplungertypedial test indicator as its name suggests works on a plungerprinciplewhilethelevertypedialtestindicatorhasastylusonthe end The lever stylus is usually ball-or pear-shaped and isfixedtothedialtestindicatorwithafrictionfitmeaningthatitcanbemovedupanddownontheendofthedialtestindicator

throughawidearctoputitintothebestpositionforuseThe plunger type dial indicator usually has a maximum

plungermovementoffrac12in (12mm)butplungermovementsofupto2in(50mm)areavailableTheplungertypedialindicatoris non-reversing and needs an adaptor to enable it to clockholes true Instead of a stylus it has an interchangeable endoften with a ball fitted various interchangeable ends areavailableoryoucanmakeyourownThe lever dial test indicator has a much smaller range of

travelarangeof0008in(02mm)isverycommonItisusuallyeither self-reversing (itmoveswhen in contact with theworkdependingonwhichwayitismoving)oritmaybereversedbyusinga lever on the sideof thedial test indicator both typesarequite commonSince the stylus isdelicate combinedwithitslimitedtravelrangeyoumustbeverycarefulnottobreakitAplungerdialindicatorcanbeusedasadirectreadoutofthe

travel and will be found to be very accurate Owing to therelativelylongtravelifyouwantedperhapstooffsetthecentreofabitofbar in the four-jawchuckby0125in (318mm) thiscanbedonebyturningthechuckbyhandandsettingthebaruntil the indicator travel shows 0250in (635mm) which is0125in (318mm) offset The lever dial test indicator is of nouseforgivingdirectreadingslikethisbutshouldbeusedasacomparatorwherethereadingtakenisforexamplezeroatallpointsofthetravelThedial test indicator is usuallymounted on amagnetic or

vacuum base but is sometimes fixed to a block that can beclampedtothelathemostoftenonthecrossslideSometimesthedialtestindicatorcomesasacompletekitincludingvariousmountingcomponents

Clockingtheendofacastinginafour-jawchuck

Four-jawChuck

To set thework up in an independent four-jaw chuckwe firstneed to know what part of the workpiece should be on thecentre If theworkpiece is a castingwemay have an outsidediameter or a hole that needs to run true in this case wewould put a dial test indicator onto the work and adjust thechuckalittleatatimeuntilthediameterrunstrueDonotturnthe chuck with the indicator in the hole Instead wind thecarriage forwards until the clock enters the hole and take areadingWind thecarriageback rotate thechuck90degreeswindthecarriageforwardandtakeanotherreadingAdjusttheworkinthechuckuntilitrunstrue

WhereacastingisstickingoutashereyoushouldtrytosupportthecastingwitharunningcentreThiswillhelptostopthecastingshiftinginthechuck

LatheCentreFinder

If there isnodiameterorholeyoumayhave tomarkout thecentreontheworkusingaheightgaugeandcentrepopitwithacentrepunchThenyoucanuseawobblerandatestindicatortosettheworktrueItwasoncepossibletogetalathecentrefinderconsistingof

a bar about 6in (150mm) long pointed at both ends with auniversaljointabout1in(25mm)fromthefrontendInusetheshortfrontendgoesinthecentrepopoftheworkinthechuckWhen you rotate the chuck by hand the pointed short endfollows the eccentricity of the centre hole which ismagnifiedaboutsixtimesatthetailstockendYouthenjusthavetoadjustthechuckuntilthetailstockendisrunningtrueatwhichpointthe centre in the work will also be running dead true I donrsquotknow anyone who makes these and second-hand ones areextremelyrare

Asimplehome-madecentrefinder

You can make a simple version of this that works well byusingamillingmachinepointedcentrefinderThisisaparallelbarwithaseparatemoveablepointedendThetwocomponentsare held together with a spring inside You need the pointededge finder a Morse taper parallel adaptor (the Morse tapershould fityour tailstock)aspringandashortstubofbar thatwillfitinsidethetaperedholderrsquosboretostopthespringgoingrightthroughPuttheshortstubofbarintothetaperinsertthespring follow up with the centre and put the Morse taperadaptorintothetailstockBringthetailstocktowardsthechuckuntil the centre of the centre finder is in the centre pop ThespringwillholditinplaceTousetheimprovisedcentrefinderput a dial test indicator onto the parallel part of the centrefinderrsquospointandrotatethechuckbyhandThepointwillrotateeccentricallyadjust thechuckuntil thecentre finderrsquospoint isrunningtrue

Usingascribingblockwithadialtestindicator

Move the tailstock along the bed until the point of thewobblerisinthecentrepopontheworkPutthetestindicatoronthefrontdiameterofthewobblerandadjustthechuckjawsuntilthewobblerisrunningtrueWhensettingupacastingorsomethingsimilarwherenotall

of the diameters are machined you should use the dial testindicator on diameters thatwill not bemachined such as theinsideofaflywheelrimWhenyouhaveturnedallthefinisheddiameters they should then be true with the unmachineddiametersSetting work in the four-jaw chuck depends on the

componenttobemachinedIfyouareusingroundmaterialyoucansetittoruntrueusingadialtestindicatorHoweverifyouaresettingaroughcastingthevariationofsizeandroughnessofthecastingsmaywellbeunsuitableforadialtestindicatorThere are alternativemethods of settingwork up in a four-

jawchuckespeciallyforcastingsOneofthesimplestmethodsis toholdasquarebar in the lathetoolholderandusethis tosetthejobtrueInuseyouwindthebaruptotheworkandsetthedial tozeroorotherwisemakeanoteofwhere it isWindthebaroutorawayfromtheworkTurnthechuck180degreesand wind the bar up against the work again You can

immediatelyseewhichwaythebarneedstomovesothatitisrunningtrueAdjustthecastinginthefour-jawchuckandmovethecastingtowardsthecentrepointRepeatuntilthecastingisrunning true This method is also useful if you are setting asquarebar to run true Justcheckeach faceof thesquarebarwiththebitofmetal

Settingacastingbyusingasquarebar

StickyPinMethod

An alternative the sticky pin method is especially suited tolocomotive wheels or flywheels An ordinary household pin ismounted in plasticine or Blu-tack perhaps stuck on the lathetool and is arranged to point to the inside diameter of thewheelor flywheel thearea that isnotmachinedbut is leftascastAdjustthecastinguntiltheunmachinedfaceisrunningastrueasyoucangetitandthewheelisreadytoturnThestickypinmethodisalsousefulforsettingupworkthathasachuckingspigot such as a locomotive smokebox door Just hold thechucking spigot in the four-jaw chuck and adjust the castinguntilitrunstrueontheoutsidediameterandthefrontface

Usingacommercialstickypintosetworktrue

Themethodsofcentringworkinthefour-jawchuckthathavebeen discussed are also suitable for setting work true on thefaceplate The next chapter looks at turning between centresandusingthefaceplate

6TurningbetweenCentresandFaceplateWork

Thischapterdealswithbasicturningbetweencentresandthenintroduces turning with the work mounted on the lathefaceplate

Headstockcentreanddriverplate(alsoknownasacatchplate)

TURNINGPLAINBARSBETWEENCENTRES

The most basic way of holding work for turning is between

centres Turning between centres is literally holding thecomponenttobemachinedbetweentwocentreseachofwhichhas a 60-degree included angle The headstock centre usuallygoes round with the headstockmandrel although some olderlatheshadanon-rotatingcentreandthedrivetotheworkwasbyapulleymountedontheworkThetailstockcentreisoftenafixedcentrethatdoesnotgoroundalthoughcentreswithballbearingscalledrunningcentresarereadilyavailable

Tailstockplaincentre

The component to be turned usually a shaft has a female60-degreecentreinbothendsthatisusedtosupporttheworkThe work can be turned round between centres so that bothends of the shaft can be machined Because the work ismountedbetweencentresbothendsoftheworkwillbetruetoeachother

Tailstockrunningcentreso-calledbecauseitrunsonballraces

CentringtheBar

FirstwehavetoputthecentresintoeachendofthebarIfthebarisshortsayuptoabout6inlongholdtheworkinthethree-jawchuckanduseacentredrillinthetailstockdrillchucktoputacentre intothebarAcentredrill isashortdrillwithasmallpilot on the end that has a 60-degree taper to the bodydiameterAbettermethodof centring thebar especially longbars is by using a three-jaw chuck and the fixed steady Thebarisheldinthethree-jawchuckwiththeotherendsupportedin the fixedsteadyand thecentre is formed in theendwithacentredrillAusefultoolthatcanbeusedtofindthecentreoftheshaftis

thecentresquarewhichisametalbladewithaVeeonitthatlocatesonthediameterofthebarMarkalineacrosstheendofthebarwitha scriber turn the centre square90degreesandthenscribeanotherlineWherethetwolinescrossisthecentreof thebar Tomake it easier to see the scribed linesblackenthe end of the bar with a permanent felt tip marker beforescribingCentrepunchthepointwherethetwolinescrossandput a 60-degree centre in each end of the bar using a centre

drill in a power drillHold thebar in a bench vicewhile doingthisPutacentredrillintothetailstockdrillchuckandinsertthebar in the three-jaw chuck Make sure the lathe is on a lowspeedabout300rpmwindthetailstockinandjustlightlycleanupthecentreholewiththecentredrilltotrueitupAnotherusefultooltofindthecentreofabarisabellcentre

punchThiscomprisesaconewithacentrepunchinthemiddleIn use place the bell end on the end of the bar and tap thecentrepunchwithahammertomarkthecentreTheendofthebar though needs to be reasonably square if using the bellpunchmethodThere are other similarmethods of centring bars but those

givenherewillbealltheturnerneedstolearn

Turningbetweencentres

Centringthebarusingthefixedsteady(Notethatthefrontclampisnormallydoneupwhileinuse)

Asimplecentresquare

Crosssectionofbellcentrepunch

MachiningtheBar

NowweneedtomountthebarbetweencentresThisissimplyamatterofputtingthebarbetweencentresandtighteningthetailstocksoitislightlypressingintothecentreintheendofthework To drive the work a carrier is fixed to the shaft andengagesapininacatchplatemountedonthelathemandrelAcatchplateissimplyablankdiscwithapinstickingouttodrivethecarrierthat isfittedtotheworkThecarrier isfittedtotheworkusinganAllenscreworboltTostopanymovementofthebarinrelationtothecatchplatethecarriercanbewiredtothecatchplatepinThiswill stop thecarrierand thework flappingaboutItisparticularlyimportanttostoptheworkfrommovingin relation to the catchplate when screwcutting betweencentres

Facingoffabarusingthehalfcentre

Nowthatthebarissafelymountedbetweencentreswecanstart turning it tosizeNormally the first thing todo is to facetheendsofthebartothefinishedlengthDecidewhichendofthebarhastheshallowercentreWewillmachinethisendfirstYouwillneedahalfcentreso-calledbecausealmosthalfofthecentre is missing This means the lathe tool can reach rightacrosstheendoftheworkwithouttouchingthehalfcentreWhenusinganyfixedcentreinthetailstockputabitofoilor

grease into the centre before use and top up as necessaryLightlywindthetailstockbarrelagainstthecentreandlockthebarrel so it canrsquotmoveSwitch the latheonandwind the toolacross to clean up the end Reverse the work and clean theotherendupat thesamesettingBothcentresshouldnowbethesamedepthMeasuretheoveralllengthofthebarTakethefinished length required from the overall measurement youhavejustmeasuredDividethisbytwoandthisishowmuchweneed to take off each end of the shaft so it finishes at therequiredlength

Askimmedbar

Ifyouhaveonechangethetailstockhalfcentretoarunningcentre if you donrsquot have a running centre change to a fixedcentreThehalfcentreshouldonlybeusedwhenfacingtheend

of the bar We will nowmachine the rest of the bar For thepurposeofthisexamplewewillassumethebarhasafinisheddiameter in themiddle with a step at each end First we willmachine the overall diameter to size To do this we need toskimthediameterandcheckthesizeTakeafinecutalongthebarusingthefinefeedifyouhaveoneMeasurebothendsofthebar Ifyouhavesetthelatheupcorrectly(seeChapter2)thebarshouldbeparallelIfitisnotadjustthetailstockbeforecontinuingAssumingthebarisparalleltakeanothercutortwosothatyouareabout01mmlargerthanthefinisheddiameterNowmove the tool in until almost at finished size and take alight cut about 10mm long along the bar Repeat this cut toensure the tool is notpushingoffMeasure thisdiameter youwill probablyhave towind the tailstockbarrel back toget themicrometerontotheendofthebarOnlymovethebarrelbackdo not slide the entire tailstock backMeasure the bar to findouthowmuchtoremovefromthediameterTakeanothershortcutandcheckforsizeWhenthebariscuttingtosizemachineall thewayalongYouwillprobablyhave to take twoor threecuts at the same setting until the bar ismachined to finishedsizeNowwewill turn the stepson theends Toensure that the

stepsare thecorrect lengthwewilluse thebedstopSet thebedstopthenwindthetopslidesothatthetoolisjusttouchingthe end of the bar For this exercise we will make the steps12mm long Wind the top slide along until the tool is justtouching the end of the turned bar Wind the top slide along119mmWecannowroughoutthestepateachendTurntheenddowntoabout02mmabovethefinisheddiameterYoucanusethefinefeedbutmakesureyouknockthefeedoffbeforethecarriagereachesthestopandfinishuptotheendbyhandRepeat for the other end Wind the top slide along theremaining01mmto12mmandfinisheachendinthesamewayasyoufinishedthemaindiameterDonrsquotforgettocleanupthefaceoftheshoulderyouhavejustturnedCongratulations you have just turned an accurate shaft

Donrsquotworryiftheshaftisatinybitundersizeyoucanprobably

makethematingholestofit

Thefinishedshaft

Usingachuckandarunningcentre

Usingthemethodsetoutaboveyoushouldnowbeabletoturn any shaft you require within the capacity of the lathe Avariationoftheabovemethodwheretheshaftissingle-endedistoholdoneendinthethree-orfour-jawchuckandsupporttheotherendwithacentreinthetailstock

Alargefaceplatesmalleronesareavailable

FACEPLATEWORK

Another basic way of holding work is on the faceplate Thismethod is used when the component is too large or isawkwardly shaped andwould be difficult to hold in a three-orfour-jaw chuck Usually the work is clamped directly onto thefaceplate often with a packing piece behind it to protect thefaceplateThefaceplateshouldbeflatandtruesothefirstthingtodo

whenyougetthelatheistocheckthefaceplatewithadialtestindicatorCarefullycleanthemandrelnoseandtheinternalholeinthefaceplateMakesurethemandrelcanturnfreelybyhandwith the lathe switched off and check that the face of thefaceplateisrunningtrueasclosetotheouteredgeasyoucanget If it is runningtrue runthetest indicatoracross the frontfaceofthefaceplatethisshouldbetrueaswellIfthefaceplateis running out itwill need to bemachined Put the lathe intobackgear if ithas it (topbackgearwillprobablybe fine)Youwill need a carbide-tipped tool ideallywith a small 45-degreechamferonthetipBringthetooluptothefaceplateand lockthe carriage Next you need to lightly face the faceplate right

acrossitsdiameterIfyouhaveapowercrossfeeditwillmakelight work of this but if not you can feed across by handFortunatelymost faceplateshavea series of rings on them toaid in setting up the work Machine the faceplate from theoutsidetothefirstringandstopforarest feedtothesecondring and so on until finished Depending upon how badly outyourfaceplateisyoumayhavetodothismorethanonceuntilit iscleanedupbutwhen it isdoneyouwill rarelyneedtodothisexerciseagain

Machiningaholeinablock

Asmentionedpreviously the ringsmachined on the faceplateareguidestohelpyousetuptheworkThiswilldoiftheworkisaroundcomponentbutweneedadifferentmethodiftheworkis square Take a block of metal for example that has beenmachinedalloverWewanttomachineaholeinit2infromoneedgeand1in fromanother edgeMarkout thepositionof theholeandcentrepunch it Put adeadcentre into the tailstockholdtheblockontothefaceplatebringthetailstockuptowardsthechuckandlockitWindthetailstockbarrelandcentreuptothe component and engage with the centre pop Lock thetailstock barrel Clamp the block to the faceplate using somepackingpiecesandfourclampsontheblockTheholeisnowoncentreandwecanmachineitinthecorrectplaceIf we need more than one hole placed accurately in the

componentwecanusetoolmakerrsquosbuttonstoensuretheholesare in the correct place Toolmakerrsquos buttons usually come insetsof fourOnebutton isusually longer than the rest soyoucanstillclockthediameterwhenitisclosetoanotherholeSetsare often available second-hand on eBaywhile they probablyhaveanobscureAmerican threadyoucanclamp themto theblock using your own BA or metric screws together with awasher

Settingupthefaceplateusingthetailstock

Asetoftoolmakerrsquosbuttons

Tofitthemtothecomponenttobeboredmarkoutdrillandtap holes in the approximate positions where the holes areneeded If you need a pair of parallel holes place thecomponentonasurfaceplate looselyfitthebuttonsandpushthem down onto a parallel or similar block of the correctthicknessandnipthescrewsupThespacershouldbesmallerthanrequiredbyhalfthediameterofabuttonIftheholesneedtobeacertaindistanceapartuseaspacer

of the correct size between the buttons (Remember tomake

thespacersmallerbyonediameterofthebutton)

Settingupacomponentusingtoolmakerrsquosbuttonstogetafixeddistancefromtheedgeofacomponent

TherearelotsofdifferentwaystosetthespacingofbuttonsItismainlyamatterofcommonsenseCastingsandflatcomponentscanbeboltedtothefaceplate

for machining A typical example of a flat component is aneccentric strap This type of component is usually made of acomponentthatiscutinhalfandboltedbacktogetherAholeisthenboredinitonthecentrelinetofittheeccentricThistypeofcomponentisoftendifficulttoholdinthelathechuckandisprone to distortion Castings are often too large to fit into alathechuckandso the faceplate iscalledon toundertake theworkAcastingcanoftenbebolteddirectlytothefaceplatetofacilitateeasymachining

Settingupacomponentusingtoolmakerrsquosbuttonstogetafixeddistancebetweenthecentresofacomponent

Work on the faceplate is often an odd shape or is set off

centreThiscauses it tobeunbalancedandasaconsequencethe lathemayvibratewhile thework is turningTocounteractthis tendency the faceplate should be counterbalanced byboltingweightsontoitAusefulsourceofweightsisthelathersquoschange wheels By bolting a change wheel or two onto thelightersideofthefaceplateyoucanbringthewholeassemblybackintobalanceAfterboltingthechangewheelsonspinthelathe by hand to check the balance The faceplate should notshowatendencytostopatoneparticularpointWhenyouarehappy that the faceplate is in balance the work and balanceweightsareboltedontightlyandsothattheworkdoesnotfoulthe lathewhen turnedbyhand switch themachine on in lowback gear to check for vibration Depending on what you areturning you should be able to run in top back gear or evenbottomdirectspeed

Asimpleclampsetisveryusefulwhenmachiningacastingonthefaceplate

TurningaFlywheel

Oneofthemainusesofafaceplateisturningalargediameteriron casting typically a flywheel or a locomotive wheel for asteamengineTheflywheelshouldbemountedsothattheinneredgeoftherimandtheouteredgeofthehubruntrueIfeitherofthemrunsoutitwouldbebetterthatthehubrunsoutasthe

rimwillbemorenoticeableonthefinishedengineClamp the flywheel down with some packing under the

spokessothatyoucanturnrightacrosstherimBecarefulthatyouclamptheflywheeltightenoughsothat itdoesnotmovebutnotsotightthatitdistortsRoughturn theoutsidediameterand facetherimusingthe

backgearUsingadirectdrivespeeddrillandborethecentrehole and either finish off with the boring tool or use a reamDonrsquot try reamingwithout boring the chances are that if youdotheholewillnotbetruewiththerimasthedrillprobablydidnotcutanaccurateholeDropdowntothetopbackgearspeedface the rim and turn the outside of the rim to the finisheddiameter Turn the flywheel over and finish the other face towidth

Astubarborsuitableforcentralizingalocomotivewheelorflywheel

TurningLocomotiveWheelFlanges

LocomotivewheelflangescanbeturnedonafaceplateYoucanpurchase blank end Morse taper arbors that fit into theheadstocktaperFitoneoftheseandturnaspigotonittotake

thewheel bore Thewheel bores should all be the same sizebut if they are different sizes machine the spigot to fit thelargestboremachinetheflangeonthatonethenmachinethespigotdowntofitthenextonemachinetheflangeandsoonIdeally the wheel bores should all be the same size but if

theyarenotproceedas followsSkimtheoutsidediameterofthe wheel flangemeasure and take it to the correct finishedsizeMovethelathetoolinbythedepthoftheflangeandturnthe tread Deal with all wheels like this machining all of theflangeoutsidediameterstothesamesizemovinginthecrossslidebythesameamounteachtimesothatallthetreadsendupthesamesize

UsingtheKeatsVeeangleplatetoturnaneccentriccomponent

KeatsVeeAnglePlate

TheKeatsVeeangleplate ismountedon the faceplateand isusedtoholdroundbarsquarebarandmiscellaneouscastingssuch as cylinders and steam chests The angle plate can bemountedanywhereonthefaceplateaslongasthelathecanbe

rotated safely and is in balance When spun by hand thefaceplateshouldnotshowatendencytostopatanyparticularplacewhenrununderpowerthelatheshouldnotvibrateAswellasholdingbarandcastingsforturningtheKeatsVee

angleplateisveryusefulformakingeccentriccomponentssuchastheeccentricsforasteamengineTo turn an eccentric use a test indicator to check that the

roundbarisrunningreasonablytrueWhenthisissatisfactoryyoucanturntheoutsidediameterofthebartofittheeccentricstrap (or component) including any step or groove requiredNextoffsettheKeatsVeeangleplatebytheamountyouwantthe eccentric lsquothrowrsquo to be Use the dial test indicator tomeasure the offset of the outside of the eccentric The offsetshouldbetwicethethrowYoucannowdrillboreandreamtheholeintheeccentricYounowhaveenoughbasic knowledge to carryout turning

between centres andwork accurately on the faceplate In thenext chapterwewill lookat holdingwork in a collet andonamandrel

7ColletsandMandrels

Thischapterexplainsallaboutholdingworkinacolletandhowyou canmake and use several different types of mandrel forworkholding

ERcollets

USINGCOLLETS

Quite a few different collet systems are to be found inworkshops Some are used for holding tools such as millingcutterssomeareusedforbarorworkpieceswhilesomemaybeusedwithbothbarandworkpiecesOne of the commonest is the ER collet which comes in

severaldifferent sizeseachhavingadifferent largediameterTheERcolletsystemallowsupto0039in(1mm)collapseofa

colletalthough in thesmaller sizesyoucanbuy thecollets in05mmincrementsA16mmcolletforexamplewillholdroundmaterialdownto15mmdiameterWhatevertheERcolletsizetheyallappear togodownto1mmminimumwhichwillclosedownto05mm

ERcolletadaptor

TherearemanytypesandsizesofERholderavailableAlltheusualMorse taper shank sizes are available and you can alsobuyvariousdiametersofextendedparallel shankholdersTheproblemwiththeseisthattheyaregreatforholdingtoolsthathave a short shank but because you need to use the holderwithadrawbaryoucanrsquotputlongbarstockrightthroughthemTo overcome this for lathe work you can also buy ER colletholdersdesignedtobefittedtoachuckbackplatethatyoucanmachine to suit your lathe so ensuring good concentricityBecause they donrsquot use a drawbar you can fit bar stock rightthroughandintotheheadstockmandrel

ERcolletadaptorfittedtoabackplateIalwaysleavebackplatesoversizesoIhavesomethingwithwhichtoclampthemdownwhenusedonamillordrill

When buying new and second-hand ER collets make surethey have the retaining groove near the nose end The older(andobsolete)EandEScollet typesdonothavetheretaininggrooveandarenotinter-changeableYouaremostlikelytofindEandEScolletsincludedwithasecond-handUnimatlatheDraw-in collets are usedwith a drawbar or collet tube The

drawbardrawsthecolletuptightbydrawingit intothelathersquosmandrelbyabar that runs through thecentreof themandreland screws into the centre of the collet Thismeans that youcannotputbarstockrightthroughthecolletToovercomethissome Morse taper collets use a hollow draw tube the collethaving an external thread tomatch the internal thread of thedrawtube

Draw-incollet

Special collets are made for the Myford ML7 Super 7 andML10 lathes These are Morse taper collets but rather thanhavingadrawbartheyareclosedwithanoseringthatfitsoveragrooveinthecolletThenoseringtightensthecolletintotheheadstockmandrelrsquos Morse taper It is extracted after use byundoing the nose piece which draws the collet out from theMorsetaperbythenosegrooveImperialandmetriccolletsareavailableuptofrac12in(12mm)diameterDead lengthcolletsareavailable that fit intoanattachment

usually fixed to the front of the lathersquosmandrel These colletsarecalleddeadlengthbecausetheydonotmovelongitudinallyunlike draw-in collets You are more likely to find collets likethesesecond-handratherthannew

BoxedsetofMyfordcollets

Deadlengthcollet

AvariationofthedeadlengthcolletistheCrawfordMultiborecolletThissystemhascolletsmadeofsegmentsheldtogetherbyspringsThecolletsareofvariablediameterandhavequitea

largeclosurerangeTheyaremorelikelytobefoundonalargercommercial lathe although you can get collets for smallermachinesWatchmakerrsquoscolletscanbeused inmost lathesbymaking

an adaptor for the headstock and a drawbar (or tube)Watchmakerrsquos collets are very accurate and can go down toverysmallsizesbuttheyhavelimiteduseinmostworkshopsYou can get a special watchmakerrsquos spindle for the EmcoUnimatlatheandthereisalsoaversionoftheCowellslathetheCW90thattakeswatchmakerrsquoscolletsFormost of thework carried out on the lathe youwill find

thatanERholder thatmountsontoachuckbackplate ismostuseful

Simpleexpandingmandrel

Simpleplainmandrel

MAKINGMANDRELS

There are several types of mandrel in common use inworkshops The most common is probably the expandingmandrelwhichcaneasilybemadeinanyworkshopInitsmostbasic form it is a bar turned to a size to fit the bore in theworkpieceItisthenthreadedwithataperedtapandslitat90degrees togive foursegmentswhichare thenexpandedbyascrewfittedintotheendofthemandrelAnother common mandrel is the tapered mandrel This is

usuallyalsquobetweencentresrsquomandrelandisoftenmadetotaperfromjustacoupleofthouovernominalsizetoacoupleofthouunder nominal size It is usually hardened and has a groundfinishTheworkpieceisheldinplacebybeingpushedontothemandreluntilitistightToremoveitjustpressitbackoutthewayitwentinWhereconcentricityisnotquitesoimportanttheworkpiece

canbeputonaplain turnedmandrelandtightenedupwithaboltandflatwasherExpandingmandrelsarealsomadecommerciallybutasyou

need a mandrel for each individual size of hole it can getexpensive if you need more than one or two different sizesCommercialmandrelscanbeobtainedwithMorsetapershanksto plug straight into the headstock Thismethod ensures thatthe mandrel should run dead true assuming both the Morsetapermandrel and theMorse taper in the headstock are bothcleanandfreefrommarksorswarfYou can also purchase Morse taper arbors with blank end

pieces from which to make your own mandrels First we willmake an expandingmandrel from a blank Morse taper arborYouwillneedtoturnthearbordowntofittheworkpieceboreIusually turn themandrelabout0010in (0025mm)oversize tostartwithandthenIdrillandtapthearborwithataperedtapThe drilled hole can go quite deep but the tapped hole onlyneedstogoinuntilthelockingbolt isabouthalfwaydownthelengthwheretheworkpiecewillsitPut the mandrel into the vice and cut along the mandrel

making four cuts around the circumferenceRetap thehole to

cleartheswarf fromthethreadandputthemandrelback intothe headstock taper Now you can lightly nip the screw up toexpandthemandrelslightlySkimthemandrel to finishedsizeuntil the workpiece will fit on without shake You can nowfurther tighten the screw so that the workpiece tightens ontothe mandrel When you slacken the screw the workpiece willcome off easily as you have skimmed it while it was slightlyexpandedYoucanmakeanexpandingmandrelfromabarheldin the three-or four-jawchuckorperhapsacollet inasimilarway Ifheld inachuck itmaynotgoback true ifyouneed touseitagainsoifpossibleyoushouldholdthearborinacolletFor aplainmandrel turn thediameter to fit theworkpiece

anddrillandtapforacapscreworaboltThereisnoneedtosplit this type ofmandrel You simply put the workpiece ontothemandrelandholditonwithaflatwasherAgainitdoesnotmatterwhetheryouuseabarinachuckorcolletorifyouusea Morse Taper blank arbor Arbors are very useful in theworkshop If youmake them fromMorse taper blanks or holdtheminacollettheycanbeusedoverandoveragain

8TaperTurningandLatheAccessories

Thischapterexplainshowyoucanturnataperusingatopslidetheuseoffixedandtravellingsteadiesandformtools

Turningataperwiththetopslide

TAPERTURNING

SometimesyouwillhavetoturnataperintheworkshopThatisa fairly easy jobWhat ismore difficult however is having toturnmatchingmaleandfemaletapers

Themethodyouaremostlikelytouseintheworkshopistoturn the two tapers with the top slide You should be able toturna taper longenough foraMorsetaperusingthismethodThemostimportantthingwhenturningtapersistoensurethatthe tool tip is at the exact centre height of the lathe This isbecause the taper will vary if the tool is not dead-on centreheightProbably the easiestmethod of turning aMorse taper is to

useadial test indicator toclocka lathecentreof therequiredMorse taper between centres The smaller end of the tapershouldbeatthetailstockendofthelatheThetopslideshouldbewoundalongthetaperby itshandwheelwhilethecarriageremainslockedThetopslideshouldbeadjustedangularlyuntilthedialtestindicatorreadszeroallthewayalongNowyoucanfinish turn the external Morse taper using an internal MorsetapersleeveasagaugetocheckthattheangleiscorrectTodothis make marks with a felt tipped pen along the taper andcheck that the test sleeve rubs evenly all the way along themaletaperAdjustifnecessaryuntilyouhaveaperfectfitToturnthematchingfemaletaperthelargeendofthetaper

willbeat the tailstockendand theboringbarwillbe invertedandcuttingon thebackof theholeDoing thismeans thataslongasbothofthetoolsareatcentreheightthetapersshouldmatchWecanusethemaletaperthathasjustbeenturnedasatestbarBoreoutthetaperverycarefullyyouwonrsquotneedtoremovemuchmaterial before the test taper goes too far intothe finishedbore Testwitha felt tippedpenuntil youhaveaperfectfitYou can turn any taper you need this way you are not

restrictedtoMorsetapersAnothermethodmostoftenusedforlongshallowtapersistouseataperturningattachmentTheseattachments are often available as extras on higher qualitylathes They comprise a slide mounted onto the back of thelathe Often the guide is dovetailed with a sliding blockattached to the cross slide to guide the tool on a taper ThedepthofcutisusuallyputonusingthetopslidesincethecrossslideisusuallydisconnectedfromthefeedscrewInthiswayit

isfreetomoveinandoutcontrolledbytheguide

Taperturningattachment

Settingthetopslidebyclockinganexistingtaper

Anothermethodweshalllookatfortaperturningistooffsetthe tailstock on its base This will make the work turnedbetween centres become tapered either large or small at thetailstockenddependingonwhichwaythe tailstock isoffset ifsettowardsthebackofthelathethediameterwillbelargerat

the tailstock end if the tailstock is moved to the front thetailstockendwill be smaller indiameter Theamountof taperthatcanbeturnedinthismannerislimitedsincetheheadstockandtailstockcentresareoutoflineThe final method of offsetting the workpiece is by using a

boringhead inthetailstockYouneedahome-madehardenedsolidcentrethatfitswheretheboringtoolwouldnormallygo(AsmallUnimatlathesizerunningcentremightbeideal)SettheboringheadsothetooltravelishorizontalYoucanthenoffsettheboringheadcentresocreatingataperThisisthesameassetting the tailstock over but you donrsquot have to realign thetailstockafterwards

Usingthefixedsteady

USINGFIXEDANDTRAVELLINGSTEADIES

The fixedsteady isusedmainly to turn theendofabaror tocentre a workpiece that is too large to fit through the chuckObviously bar stock should not protrude from the chuckmorethan is necessary to work on This is where the fixed steadycomesinThefixedsteadycanbesettothediameterofthebarsothattheendofthebarcanbemachinedsafely

Thesteadycanbesetusingachuckmountedonthistailstockadaptor

Travellingsteady

Settingthesteadybyusingachuckmountedonanadaptor

Onewaytosetthefixedsteadytosizeistoturnabitofbarin the chuck to the same size as the barwewant to use thesteadyonThenwecanmovethefixedsteadyalongthelathebedandfittheworkpieceintothechuckandinthesteadyTheendof thebar nearest to the tailstock shouldnowbe runningtrueandcanbeworkedonsafelyThebarcanbecentredrilledfacedorotherwiseworkedonAn alternative way to set the steady is to support the

tailstockendof thebarwitha threejawchuckmounted in thetailstockAdaptors to take the threejawchuckareavailableoryoucouldmakeyourownJustsupportthebaratbothendsinthethreejawchucksandsetthesteadyfingerstothebarThe fixed steadycanalsobeused to support tubes thatdo

nothaveanymaterialinthecentreThe fingers of the steady need to be lubricated regularly

while inuseThis iseasilydonebydrillinga smallhole in thetopfingerwithacountersinkinsidetheslottotakeoilThetravellingsteady ismostoftenusedwhenturningdown

small diameterbarsor screwcutting long slenderbars It boltsonto the front of the cross slide in line with the chuck and

travelsalongwhenthecrossslideismovedalongthelathebedWhen turning the travelling steady can either be set to thediameterofthebarbeforeturningandtoleadthetooloritcanbesettothefinisheddiameterrequiredandtofollowthetoolNormallythefingersaresetto leadtheturningtoolbut if thebarisroughforexampleifitisdentedorrustyitisbetterforthefingerstotrailtheturningtoolIfscrewcuttingthetravellingsteadyshould lead the toolso that itdoesnotdeflectorwearduetoaburrbeingthrownupbythescrewcuttingtoolSteadies will not be used very often but they are

indispensableontheoccasionswhentheyareneeded

Travellingsteadywithleadingfingers

Travellingsteadywithtrailingfingers

MAKINGASIMPLEFORMTOOL

Youmay often need to produce a particular shape such as aradiusonacomponentTheeasiestmethodtodothisiswithaformtoolAsanexamplewewillmakeasimpleformtooltocutahalfcircleonabarofbrassForaradiusof3mmforexampleweneedtoproducea formtoolusinga6mmdiameterdrillorreamFormaterialwewillusegaugeplateahighcarbonsteelthatcomesintheformofagroundflatbarApieceabout5mmthick and10mmwide is needed although the size is not thatimportantaslongasthegaugeplateisthickenoughtoabsorbanyturningstressesIdeallyweneedataperedreamerthatwillproduce a 6mm diameter hole somewhere along its lengthalthough you could use a parallel 6mm reamer a slot drill orendmillorevenastandardtwistdrillDrill a hole through the gauge plate and open up to 6mm

diameterAim togetagoodsurface finishon thesidesof thehole Hacksaw and file half the hole away to leave the shaperequired on the finish turned component Now we need to

harden the tool although ifweare justdoingacomponentortwoinbrasswecouldprobablygetawaywithouthardeningitHardeningissimpleenoughheattheworkingendofthetool

toredstopheatingandletthegaugeplaterestforacoupleofminutesThiswillgive thegaugeplateachance tochange itsinternalstructureReheattoredandquenchinatubofwaterThisshouldhardenthetoolAlthoughabitbrittle itshouldbefine for making a few components Stone the top of the tooluntil thecuttingedge issharp Ifnecessaryyoucanpolishtheinside of the radius that is going to do the cutting There areseveralmethodsyoucanuse includingapieceofwetanddrypaperaroundabitofbaraverysmallgrindingwheelcalledamounted point or a bit of round bar with fine valve grindingcompoundonitWhicheveryouuseaimforapolishedfinishasthe finish on the turned component is directly related to thefinish on the form tool You canmakeall sorts of simple formtools with gauge plate a typical example being a facing toolwitha30-degreechamfertofaceandchamfernuts

CopytemplatereadytouseMetal

MachiningfromaTemplate

MachiningfromaTemplate

YoucanmachineaprofilefromasimpletemplateThetemplatecanbecutfromgaugeplatewithafileormachinedbutitdoesnot need to be hardened The template could be used tomachinea large radius suchasa smokeboxdoor Inuse thetemplateismountedonablockonthelathebedandthecrossslide is kept in contact with the template by being pushedagainstthetemplatewithaballracefixedtothecrossslideInthenextchapterwewillbelookingatdrillingandreaming

9DrillingandReaming

ThischapterexplainshowtousedrillsandreamersinthelatheTherearemanydifferenttypesofdrillsandreamersTheyareessentialtomakingcomponentsinthelatheWewilllookatthevarioustypesandhowtochoosethespeedsandfeedsforusingthem

Thisdrillchuckrequiresachuckkey

TYPESOFDRILL

Drills are normally held either in the tailstock if they have aMorsetaperor inadrillchuckiftheyhaveaparallelshankA

drillchuckismountedonaMorsetapershankthatisusuallythelargestMorsetaperthatthetailstockwilltakeThelargestsizeof drill that will normally fit a drill chuck is frac12in (13mm) indiameter although larger chucks are available at a cost Thesmallest sizeofdrill thatafrac12in (13mm)drill chuckwill take isusually about 116in (15mm) This is because the larger drillchuck is incapableofclosingdownenoughto take thesmallersizesofdrillThismeanswewillprobablyneedtwodrillchucksoneforlargerdrillsandoneforsmallerdrills

Hand-tighteningdrillchuck

TherearetwomaintypesofdrillchuckOneistightenedbyusinga chuckkeywhichhasa small bevelgearbuilt on to itthatmates with the outer sleeve of the drill chuck itself Theother type is hand tightenedwhere the outer chuck sleeve isknurledtotightenthedrillthesleeveisturnedbyhandLargerdrillsabovefrac12in(13mm)usuallyhaveaNo1orNo2

MorsetapershankYoucangetMorsetapersleevestoconvertalargeMorsetoasmallerMorsetaperYoucanalsogetasmallMorsetolargeMorsetaperconverteraswell

Drillwithataperedshank

Some larger drills are also available with parallel shanksTheyaremadewithasteppeddownfrac12inparallelshankandarecalledblacksmithrsquosdrills

Blacksmithrsquosdrill

Themostusefuldrills in theworkshopcomeassetsofhighspeedsteeljobberdrillsinacaseThemostpopularsetcovers1mmto6mm increasingby01mmstepsAnotheruseful setcoversfrom6mmto10mmalsoincreasingby01mmstepsIfyouareintomodelengineeringasetofnumberdrillsfromNo1toNo60istoberecommended

Asetofmetricdrillscovering1ndash6mm

Drills are also available in different lengths Stub drills areshorter than standard jobber drills Several lengths of longseries drills are also available ranging from one and a halftimesthelengthofajobberdrilluptoseveraltimesthelength

Differentlengthsofdrills

Mostdrillshavetwoflutesbutcoredrillsarealsotobehadwith three four or evenmore flutes As their name suggeststhese are usually used for drilling out cored holes in castings

CoredrillsarenotnormallycapableofstartinganewholebutareusedforopeningupexistingholesAstandarddrillusuallyhasanincludedangleof118degrees

Stub drills and cobalt drills often have a 135 to 140 degreeangle for use on hardermaterials such as stainless steel andaircraftsteelsBack rakeondrills is oftenground radially Another typeof

pointhoweverhasfourfacetstothepointFour-facetdrillsaremuch better at starting a hole than a standard jobber drillwhich tends towanderunless followingacentrepoporcentredrill Four-facet drills also require less pressure to drill a holesincethepointisthinnerthanastandarddrillandtheyarefareasier to sharpen accurately by hand than standard jobberdrillsDormerdoarangeoffour-facetdrillscalledA002withatitaniumnitridecoating(TiN)andafour-facetpoint

Three-flutecoredrill

DormerA002four-facetdrillpoint

To drill an accurate sized hole requires two ormore stepsfirst youdrill the hole undersize (by perhapsfrac12mm) then youfollowthroughwithasizedrillThechancesaretheseconddrillwillcutdeadtosizeasitisonlycuttingasmallamountfromthediameter Obviously if you are drilling a large hole moreintermediatestepsmayberequiredSpeedsfordrillingarethesameasthosegivenforturninginthetableinChapter3

Setofcentredrills

REAMERS

There are several types of reamers available for use inworkshops again with either Morse taper or parallel shanksSomehavesizeparallelshankstheshankbeingthesamesizeas the reamer while others are availablewith shanks smallerthanthereamedsizeThereisalsothewaistedreamerwheretheshankisthesamesizeasthereamerthemiddleissmaller(waisted)andthecuttingendistheholesizeYoucanalsogetadjustablereamerswheretheendisexpandedbytheuseofascrewinthecuttingendofthereamer

Handreamerthefrontparthasaslighttaper

Straightshankmachinereamer

Waistedshankmachinereamer

Morsetapershankmachinereamer

Parallelreamersaredividedintotwotypesparallelmachinereamerswhere thecuttingdiameter is thesameallalong theream and hand reamers where the cutting end is slightlysmallerandtapersuptothefulldiameterWhen drilling a hole for reaming it is advisable to use the

two-holemethodfordrillingYouaremore likelytogetagoodsize hole prior to reaming For small reamers up to 04in(10mm) leave about 0012in (03mm) for the reamer toremoveForreamersuptofrac34in(19mm)leave0016in(04mm)and over frac12in (13mm) leave 0020in (05mm) For reamingspeedsuseabouta third toahalfof thedrillingspeed for thesamediameterFeedsshouldbefrom0002to0004in(0025ndash005mm)per toothper revMultiply the feedper toothby thenumberofteethtogivethefeedperrevolutionItisbesttouseneatcuttingoilformostmaterialsexceptfor

aluminiumforwhichparaffinshouldbeusedandplasticwhichrequirescompressedairorplainwaterYoushouldnotuseoilasacuttinglubricantforanytypeofplasticasitcanattackandordegradetheplastic

10BoringToolsandBoringHeads

Thischaptershowsyouhowtoboreholesinthelathewiththeworkheldinachuckmountedonthefaceplateorfixedtothelathecrossslide

TypicalHSSboringbar

DIFFERENTTYPESOFBORINGBARS

BoringaholetosizeisoneofthemostexactingjobsyoucandoinalatheItisrelativelyeasytoturnashafttofitaholebutitis much harder to bore an accurate hole to fit a shaft Ifpossibleyoushouldboretheholebeforeturningtheshaft

YouarelikelytocomeacrossHSSboringbarsorinsertedtipboringbarsBothhavetheirusesTheHSStoolisidealformostgeneralhole-boringjobsbuttheinsertedtiptoolisfarsuperiorfor materials such as cast iron The boring bar should be aslargeasyoucangetintotheholewhilestillallowingswarftoberemovedTheboringbarshouldonlyprotrudefarenoughtoenableitto

go completely through the bore Any more protrusion than isnecessarymay result in chatter or a dig in in the bore Thefront clearance on the boring bar tip should be as small aspossiblewithoutrubbingasstrengthisimportantBoringcanbeusedtofinishaholetosizeorsimplytotruea

holeupafterdrillingandpriortoreaming It isbesttoruntheboringtoolthroughtheholeusingafinefeedtothecarriageifyouhave the feedoptiononyour latheThe final finishingcutshouldbeputthroughtwoorthreetimesatthesamesettingtoeliminateanyspringinthetoolworkorlatheIftheholehasanintermittentcutthroughitsuchasacrossholetheholeisbestboredtosizeIt ispossible toborequite smallholes if youhave the right

tool Commercial lsquosmall holersquo boring tools are very expensivebut Ibuythemsecond-handwhenever Iseethemso Iusuallyhave a stock It is easy if time consuming to grind up smallboringbarsbuttheyareveryusefulespeciallywhenyouneedtotrueupasmallholepriortotappingorreamingEndmillsandslotdrillsmakeusefulboringtoolsAs longas

yougetthecuttingedgeoncentreheighttheywillboreaswellasaproperboringbarespeciallyinaluminiumYoucanmakesimplehome-madeboringtoolsbydrillingand

reamingaholetotakeaHSStoolbitintoasteelshankIdeallythe shank should be made of high tensile material or silversteelThetoolbitshouldbesecuredwithahightensilesocket-headedgrub screwor similar The tool bit caneitherprotrudefromthesideoftheboringbarforthroughholesorprotrudeatthe frontof theshankat45degrees ifyouareboringablindholeRoundboringbarscaneitherbeclampedintotheVeegroove

foundinsometoolholdersorheldinasplitsquareshankEithermethodissuitableespeciallyastheshankcanbeslidinoroutofthetoolholdertominimizeprotrusionSpeciallyshapedtoolbitscanbeusedtoundercuttheendof

the borewhen it needs to be screwcut and canrsquot be cut rightthrough Inserted HSS boring bars can also be ground up forundercuttingbeforescrewcuttingThereareseveralmethodsofcheckingaboreforaccuracyIf

youhavetoboretheholetofitanexistingcomponentperhapsaballraceyoucanuse theexistingcomponentasagaugeorturnupagaugeRoughout theborewithina few thouof thefinishedsize taking twoor threespringcutsUsea telescopicgaugeapairofcalliperswithamicrometeroradigitalverniertomeasuretheholeBorethestartoftheholebynomorethanonethouata timedonotgoright throughtheboreTest thefrontoftheboreifthegaugedoesnotgointotheborerunthetool right throughunderpower feedBoreout the frontof theholebyanotherthouchecktheboreandrepeatuntilthegaugejustgoesintothestartoftheholeFinishtheboreatthesamesetting checking that the gauge just enters Take a couple ofspringcutstoensuretheboreisparallelYoushouldnowhaveanaccuratelysizedholeThe trick to boring is to finish with very fine cuts Many

engineersdonotrecommendfinecutsbutIhaveneverhadaproblemaslongasthetoolissharp

Asetoftelescopicgaugesforcheckingaboreusedinconjunctionwithamicrometer

Checkingaborewithahome-madegaugeTheleadinisonethousmallerthantheborerequired

USINGABORINGHEADINTHELATHE

AnothermethodofboringacomponentinthelatheistoboltitdowntothecrossslideWhentheworkpieceisbolteddownandtheholeposition is linedupwith theheadstock youcanboretheholeintheworkpieceinseveralwaysFirst however you might need to put a hole into the

workpiece to clear the centre of the hole out of theway Youcandothisbyusingadrillinathree-orfour-jawchuck(smallerdrillscouldbeusedinadrillchuck)Startwithasmalldrillandworkupalmosttothefinishedsizeoftheholetobebored

Boringaholereadyforreaming

Toboretheholethefirstoptionistoholdaboringbarinthethree-jaw chuck This is a good basic method of boring aworkpieceonthecrossslideTheonlyawkwardbitisadjustingtheboringbarsothatasizeholeisboredThisisusuallydonebyanadjustingscrewpressingontothebackofthetipoppositethe cutting edge The tip itself is usually clamped by a grubscrewthroughthesideoftheboringbarHoweveryoucanuseaboringbarthatisafewthouundertherequiredsizeandfinishoffwithareamerA similar way that is easier to adjust is to use the same

boringbar in the independent four-jawchuckThen insteadofadjusting the tip in the boring bar you can adjust the entireboringbar inthefour-jawchuckThisasyoucanimaginewillbealoteasierthantryingtoadjustthetipintheboringbarThethirdmethodofboringworkonthecrossslideistousea

properboringheadThis iseasy toadjustas it isdesigned forthisverypurposeFinallyyoucouldusea lsquobetweencentresrsquoboringbarwhich

isheldbetweentheheadstockandtailstockcentresThisistheonly option when you are doing a long bore such as a largecylindercastingforalocomotiveortractionengine

Boringtheholeusingthefour-jawchuckmethod

Usingtheboringheadinthelathemandrel

Unlike when you are facing and boring a component in achuck you will not be able to face across the front of thecomponent (Boring heads with the ability to face across theworkareavailablebutareunlikelytobefoundintheamateurrsquosworkshop) Thismeans you will have to face across the workwith a flycutter in order to keep the face true with the boreFlycutters are available quite cheaply or you couldmake yourownandholditinthefour-jawchuck

Aflycuttersuitableforfacingthefrontofacomponentthathaspreviouslybeenboredonthe

crossslide

11KnurlingRadiusTurningandProductionMethods

This chapter explains how to use knurling tools and radiusturningtoolsaswellasusingbasicproductionmethods

KNURLING

Knurlingistheprocessofformingorimpressingapatternonapiece of metal often for the purpose of making a grip for apieceofequipmentsuchasaknobBothstraightanddiamondknurlscanbeproduceddependingonthetypeofknurlyouareusing Diamond knurling is usually done with two knurlingwheelsalthoughsingle-wheeldiamondknurlsareavailableKnurls are also available in fine medium and coarse sizes

although the size is relative fromdifferentmakers The speedfor knurling is usually about half of the turning speed for thesame diameter bar Normal knurling is of the male patternwheretheknurlingconsistsofraisedpyramidsFemaleknurlingismuchrarerandconsistsofdepressedpyramidsThere are threemain types of knurling tool but only two of

these are found in the average workshop The first type ofknurling tool is the so-called lsquocutrsquo knurling toolwhichactuallycutsaknurlratherthanpressestheknurlintotheworkThisisaspecialized tool more often used in industry and is veryexpensivesoitisnotfoundinmanyhomeworkshops

lsquoBumprsquoKnurling

The most common knurl is the single-or double-wheel knurlsometimes called a lsquobumprsquo knurling tool The wheels aremountedat the frontof the tool This typeof knurl is pressedintotheworkbyusingthecrossslideandcanproduceagoodqualityknurlHowever itdoesputveryheavypressureonthemandrelandlathebearings

Acommerciallyavailablestraddleknurlingtool

StraddleKnurling

Thebest typeofknurl foroccasionaluse is thestraddleknurlwhich has two knurling wheels that completely straddle theworkpieceThistypeofknurldoesnotputastrainonthelathebearings and so is preferred bymost lathe users (Two-wheelknurlingtoolsareavailablethatresemblestraddleknurlingtoolsbut they donrsquot open up to take anything more than smalldiameters relying on pressure at the side of the job like alsquobumprsquoknurl)To set the straddle knurl up wind the tool against a bit of

plateheldontothesideofthebarRemovetheplateandmovethetoolinbythethicknessoftheplatehalftheknurldiameterandhalfthebardiameterThiswillputthetoolontothecentrelineofthebar

Settingtheknurlingtool

In use set the knurling wheels to the centre as describedabove wind the knurls onto the outside diameter of the barwindtheknurlawayfromthebarandmovetheknurlingwheelsclosertogetherbytwicethedepthoftheknurlpatternSwitchthelatheonandwindthetoolbackontothecentrelineandthetool should start to form the knurl You can now traverse theknurlingtoolalongtheworkpieceto formtheknurl remembertousecuttingoilNote that theknurlsshouldhavechamferedsidesifyouaretraversingalongtheworkpieceYouneedtogodeepenoughsotheknurlisfullyformedbut

notsodeepastodeformtheknurlBecausetheknurlstraddlestheworktheknurlsstartoff independentlyandmaynotbe inalignment around the diameter Once you start moving theknurlingtoolbackwardsandforwardsalongtheworkhoweverthetoolshouldlineitselfupThismeansyoumayhavetoturndownorpartoffthebarwhereyoustartedtheknurlIfyougotoodeepespeciallyinaluminiumthewholedepth

ofknurlcouldgetdestroyedandevendropoff theparentbarThis is called flakingKnurling isnotadifficultprocessa littlepracticewillsoonhaveyouknurlinglikeaprofessionalengineer

Anaccomplishedbitofknurling

AformtoolcuttingaballTheinsetviewshowstheformtoolandafinishedball

RADIUSTURNING

Sometimesweneedtoformanexternalradiusontheendofabit of bar perhaps for a ball-shaped handle We can use asimple lathe attachment to do this Basically the attachment

consists of a short turning tool mounted onto a U-shapedcomponent that is arranged to pivot on another U-shapedcomponentheldinthelathetoolpostBy pivoting the attachment back and forth a radiuswill be

generatedForatrueradiusthepivotpointshouldbesetonthecentrelineofthebarTheradiusgeneratedwilldependonhowfarthetoolbitissetbackfromthecentrelineoftheworkpieceTosetthetoolupwindtheattachmentuptoaplateheldto

the sideof thebar youareworkingon remove theplate andwindinthewidthoftheplatehalfthewidthofthebarandthewidthofthefixturetothecentrelineofthepinThiswillputthepivotonthecentrelineThenyoucansetthetooltotheoutsidediameterofthebarThiswillproduceaballthesamediameterasthebarTo turnan internaldiameteruse the samemethodbut the

turning tool will need to pass through the centre of the pivotand out the other side You will be limited to shallowdepressionsratherthanlargesemicirclesbutthistechniquecanstillbeusefulonoccasionThealternativemethodof formingaball iswithaball form

tool

Astopbarblockforthecarriagestop

PRODUCTIONMETHODS

PRODUCTIONMETHODS

Foreaseofproductionthefirstthingyouneedtouseisabedstop (see Chapter 5) The chances are that you will need tomakeyourownTheoneIuseisveryversatileandconsistsofablockmountedatthefrontofthelatheheadstocktogetherwitharodtoactasthestopDependinguponwhatyouaredoingitmaybeusefultohave

morethanonestopbareachwithitsownseparatestopblockInusethebarisinsertedintothemainblockasfarasthestopblock(if fitted)andlockedinplaceThefirststopbarcouldbeusedto facetheworkpieceandthesecond(shorterbar)couldbe used to turn along the diameter while a third bar couldpositionthepartingofftoolAnalternativeadditiontothestopbarcouldbeawasher(orwashers)ofknownthicknessplacingthewasher(orwashers)onthebarwillextendthestoppositionbythethicknessofthewashersusedAusefultipistostampanumberonthestopblockssothat

eachone isnumberedYoucouldalso stamp the thicknessonthewasherssoyoudonrsquothavetokeepmeasuringthemandjustpickthemupinthecorrectorderItsavesalittletimeandhelpsavoiderrorsThe whole point about using a stop is the consistency of

positionwhichistransferredtotheaccuracyofthecomponentit gives Once you have learnt to use a stop youwill wonderhowyoumanagedwithoutitEvenforone-offcomponentsitwillsaveyoutimeForatypicalone-offsteppedshaftsetthestopsotheturning

tooljustfacesthebarandfaceoffMove the top slide along for the length of the turned step

requiredTurnthestepYounowhaveastepontheendofthebarofaknownlengthNofiddlingnomeasuringndashyouknowitiscorrectUsing the bed stop offers a simple way of doing repeat

turning of lengths and diameters in the lathe Stops are notlimited to production methods they are very useful formachiningone-offsaswell

A single stop bar will serve for much of the work you aredoingbutsometimesyouneedmorethanonestopTheanswerhereistousemorethanonestopbarinconjunctionwithastopblockEachbarhasitsownstopblockthatcanbetightenedupThenyoucaninterchangethestopbarsandeachbarcanbesettotherequiredlengthbyusingavernierorruleYoujustsetthetwostopblockstothedifferencerequiredandlockthestopbarintheholderasnormalWhenyouneedmorethanoneofeachitemitisveryeasyto

save time in theworkshop once the lathe is set up you canmake several items in quick succession A typical example ofthis type of production is a simple spacer Set a facing andchamferingtoolinonetoolholderapartingofftoolinanothertoolholderandadrillinthetailstockchuckThefacingtoolandparting off tool are in fixed positions to each other so it is asimplematter of drilling thehole facingoffwithone tool andparting off with the other As long as the gap between thepartingofftoolandthefacingtoolremainsconstantthespacerswill remain at the samewidth each time youmachine one ofthemTheeasywaytosetthethicknessofthewasheristofaceoff

theendofthebarbringthepartingofftooluptothefinishedface and lock the cross slide Wind the parting off tool backslightly so you can move the bar forward in the chuckMeasuring with the vernier calliperrsquos depth rod from therighthandfaceofthepartingofftoolbringthebaroutslightlylonger than is needed for the washer thickness Using thetailstock chuck drill the hole using a centre drill for the firstwashertoensurethedrill runstrueNowsetthefacingtool inpositionfaceoffthewasherandpartofffromthebarMeasurethe washer and adjust the facing tool either way so that thethicknessof thewasher iscorrectPull thebar fromthechuckslightlyfurtherthanthefacingtoolsothateachwashercanbefaced to lengthYoucanmakeasmanywashersasyouneedall of the same thickness The same applies to nuts and anyothercomponentthatneedstobeasetlengthIfmakingboltsor screws theprinciple is thesamebutyou

willneed to turndown thediameter tobe threadedThis timethedifferencebetweenthepartingofftoolandtheturningtoolisthethicknessoftheheadInordertofacetolengthhoweverawasher of a known sizemust be inserted between the stopblockandthecrossslideThiswasherwillbethelengthoftheturneddownportionofthecomponentIfyouwanttomakeabatchofcomponentsbutdonrsquotwantto

keepmovingorchangingtoolsyoucanmachinethebatchonestepata timedoingoneoperationoneachcomponentbeforedoing the next operation on all the components Repeat thisuntil the complete batch ends up as completed componentsYou have the added advantage that the components willprobablyallbethesameshapeandsizesomethingthatisnotalwayspossiblewhenmachiningeachcomponentindividuallyTo make a batch of components such as washers to the

samethicknessisquitesimpleSetupapartingtooltopartoffthe components and set up a facing tool to face thecomponentsThedifferenceinpositionbetweenthefacingtooland the parting toolwill be the thickness of thewashers Youcanadjustthethicknessofthewasherbymovingthefacingtoolbackwardsor forwardswith the topslide toadjust it The rearpartingofftooldoesnotmoveotherthantopartoffthewasher

Makingwasherstothesamelengthusingfixedpositiontools

TAILSTOCKTURRET

AnotherusefulaccessoryisthetailstockturretThisisarotatingheadthatisusuallysetbackatanangleItfitsintothetailstockof the lathe and has multiple stations to take different toolsoftenitwilltakefourfiveorsixtoolsThebenefitofthisisthatitcanhaveabarendstopacentredrilladrillacountersinkatapandadieoranycombinationthereofallsetupreadytousein sequence The tools normally fit into holes bored into theturretToavoidtoolsstickingouttoofar it isbesttousestubdrillsinsertedintoroundbarsthatfitintotheturret

Anindexingturretthatfitsdirectlyintothetailstockofthelathe

YoucaneitherdrillandtaptheroundbarsoruseLoctite tosecure the drill in the round bar You can also buy roundadaptorswithaJacobschucktapermachinedontheendtotakechucksAnothermethodoffittingchucksistodrillandtaptheround bar to take chucks with threaded extensions ThesechuckscanoftenberetrievedfrombrokenBlackampDeckertypedrillsDieholderscanslideonapieceofroundrodintheturretFor

smaller diameter threads you can stop the die from rotatingusing your hand There is no need to reverse the lathe whenthreading just stop it and spin the die off by hand the samegoes for taps For larger taps and dies you can use a shorttommybartostoprotationbutmakesurethatthetommybarpositionisclosertotheworkthantheendofanyofthedrillsorthetommybarwillsnapthedrillsifyouletgoofitorifthetapordiejamsupYoucanalsomakeorbuyarunningcentretofitintotheturrettosaveremovingitwhenyouneedtousealathecentreOnlydothiswithsmallorlightworknotheavybarsorfor largecutsWhenused inconjunctionwithagoodbedstop

system a tailstock turret becomes a very versatile productionfacilityTheturretcanbemademoreversatilebyfittingalever-feed

tailstockattachmentoracapstan-style feedattachmenttothetailstockturretEitheroftheseattachmentswillmaketheturretveryfastinoperation

Anindexingturretsetupwithastopandacentredrill

Standardlever-feedtailstock

SECONDOPERATIONWORK

SECONDOPERATIONWORK

Sometimes it is necessary to do second operation work on apart-machinedcomponentUsually thiswillbeon theoppositeend to the one already turned There are two main ways ofholding theworkpiece in the correct position for furtherworkthechuckbackstopandsoftchuckjawsThechuckbackstopisquitesimpletomakeItconsistsofa

draw-incolletapieceofplainbarforthestopabitofthreadedbar a nut and a top hat collar The collet goes into the lathemandrelandisdrawninbythethreadedbarThethreadedbargoesthroughthemandrelandislockedinplacebythenutandthe tophatcollarat the left-handendThe tophatcollar is toprotecttheendofthemandrelThestopbarfitsthecolletandispositionedsothattheworkislocatedattherightdepthinthechuckThismeansthateachcomponentput intothechuckupagainstthebackstopwillalwaysbeheldinthesameposition

Capstan-stylelever-feedtailstock

Adraw-inbackstop

Softjawswithhexagonsadded

The secondmethod is to hold the component in soft jawswhich are bored out to hold the component (see Chapter 5)ThismeansthecomponentshouldrundeadtrueandeachonewillbeheldinthesamepositionreadytobemachinedSoft jaws tend to be used for larger components while the

backstop ismore likely tobeused forbarworkYoucanboltextension pieces to soft jaws to hold larger diameters orextensions can be machined to make a nest to take largercomponentsWhensoft jawsarewornoutandfaceddowntoo

lowforfurtheruseyoucanboltapieceofhexagonbartoeachjawtogivethemanewleaseoflifeIfyouhaveabatchofthreadedcomponentstofinishonthe

second end you can screw them into a bit of bar held in thechuck If theyarehexagonbolts just tightenup lightlywithaspanneriftheyareroundheadandtheheadwillbemachinedlateryoucouldtightenanduntightenthemwithapairofpliersThe more production work you do the more varied the

methods you will learn and the quicker you will makecomponentstoahighstandardofaccuracyA sensitive drilling attachment can be very useful when

drillingwith tiny drills The feed is by hand which gives it itssensitivity The attachment can also be used for small tapswherethetravelisfairlyshort

Machiningscrewheadsbyholdingthescrewinathreadedmandrel

Asensitivedrillingattachmentthatfitsintothe

tailstockchuck

ThisVeeattachmentisusedforcrossdrillingandcanbeusedintheheadstockorthetailstockofthelathedependingonthelengthofthebartobecrossdrilled

ThisisarevolvingtaperforthetailstockIfyoufitadrillchucktoityoucanuseitasarunningsupportforsmallbarwhereacentreisnotpermissible

12TapsDiesandScrewcutting

Thischaptershowshowtousetapsanddiestocutinternalandexternal threads in the lathe Italsoexplainshowyoucansetupasimplegeartrainandcutascrewthreadwiththehelpofascrewcuttingdialindicator

Atypicaldie

CUTTINGTHREADS

Threadcuttingeither internalorexternal isan importantpartoflearningtousealatheThepurposeofathreadisusuallysothatyouareabletoholdpartstogetheralthoughotherusesforthreadssuchasleadscrewsandfeedscrewsformachinetoolsareoftencalledfor

Safetyhasalreadybeencoveredindepth(seeChapter2)butafewextrawordsonsafetywhenthreadcuttingarecalledforWhen tapping a hole or threading a bar from the tailstock atailstocktapordieholderisoftenusedForthesmallerthreadstheholdershaveaknurledbodyandrotationcanbestoppedbysimplyholdingthebodyoftheholderinyourhandAslongasyoukeepyourhandawayfromthechuckandany

sharp lathe tools on the cross slide you should be fine (ifpossible remove either the tool holder or the tool itself )Providedthereisnothingtocatchorsquashyourhandonyoucan hold the knurled tap or die holder in your handwhile thelathe is running slowly under power and releasing the holderwhen the full length of the thread is cut or the pressurebecomes too great for you to stop the rotation (By slowly Imeaninveryslowbackgear)For largerthreadshoweveratommybarwilloftenneedto

beusedtostopthetapordieholderfromrotatingWhenusingthe tommy bar to prevent rotation do not under anycircumstances use the lathe under power Instead switch themachinerightoffandunplugit ifpossibleTurnthetapordieholdingthetommybarwiththerighthandandstopthechuckfromrotatingwiththelefthandThere are already many published charts providing thread

data covering such factors as tapping hole sizes minimummaximum and effective diameters as well as pitches andthreadsperinchIwillnotbeprovidingthemherebutwishtopoint out that tapping size drills can vary with the materialbeingcutWhenIamtappingsmallsizes instainlesssteel forexampleIusuallydrillthehole0004in(01mm)largerthanthefigurestated in thechartThisway Iam less likely tobreakatapinthehole

HSSorCarbonSteel

TapsanddiesareusuallymadefromcarbonsteelorHSSHSStapsanddiestendtoremainsharpformuchlongerthancarbonsteeltapsbutcarbonsteelisusuallycheaperNewcarbonsteel

tapsanddieswillprobablybefineforsmallerholesandsoftermaterials but wherever possible HSS should be your firstchoice Second-hand taps and dies are sometimes availablefromtoolshopsoroneBaybutinmyexperiencetheyareoftenbluntandnotworthbotheringwith

Lubricants

Whether tapping threading with a die or screwcutting it isnormallyessentialtousealubricantevenonbrassForbrassaluminium and bronze kerosene (paraffin) or white spirit isgenerallyusedandcanwithadvantagehaveasmallamountofcuttingoiladdedFor steel and stainless steel amodernpaste-based tapping

compound or cutting oil should be used This can also beappliedtocopperthismetalcanbestickybuttakeiteasyandall should gowell I also use paste or cutting oil on cast ironAlthoughmostrecommendationsaretocutcastirondryIhavefoundalubricanttobeveryhelpful

Screwthreadpitchgauge

ThreadGauges

When following a published design you will probably use thethread sizes as recommended by the designer If you are

making a thread to match an existing thread however youneedtofigureoutwhattheexistingthreadisThisiseasiesttodoonanexternalthreadIfyouhaveonlythenuttrytofindaboltthatwillfititandusethattocheckthethreadIfyoucanrsquotfindamatchingboltandtheholeinthenutisbigenoughyoucouldtrypressingabitofplasticineintotheinternalthreadandmeasuringthatTomeasuretheexternalthreadweneedtodeterminethree

thingsusingathreadpitchgauge theoutsidediameterof thethread the pitch of the thread and the thread angle Thesethree checks will probably be sufficient to decide what thethreadactuallyisBritish threads such as British Standard Fine and British

Standard Whitworth and also the Model Engineer threadsystemhaveanangleof55degreesAmerican threads such as UNF (Unified Fine) UNC (Unified

Coarse) UNEF (Unified Extra Fine) ANF (American NationalFine)ANC(AmericanNationalCoarse)are60degreesasisISOmetricUnusually theBritishStandardCycle thread is also60degreesThe other thread youmight come across is the BA (British

Association)threadThishasathreadangleof47frac12degreesandismetricbasedThelargestBAthreadis0BAwhichhasa6mmdiameterwith a 1mmpitch TheBA series godown to 22BAbutinpracticeyouareunlikelytocomeacrossanythingsmallerthanabout14BA

TAPS

TappingistheprocessofcuttinganinternalthreadwithatapFirst a hole is centre drilled and drilled in the workpiece Irecommend that you give the top of the hole a 90-degreecountersinktogivealead-intothetapandalsotostopthetapfromthrowingupaburrontothefaceofthework

Setofhandtaps

TypesofTap

The many types of tap can be divided into hand taps andmachinetapsHandtapsarenormallyheldinatapwrenchbutcan be held in the lathersquos tailstock chuck or a purpose-madetailstocktapholder

Close-upofahandsecondtap

WhentappingbyhandstartthetapuntilitstartstobiteandgiveitanextraturnorsoReversethedirectionofthetapforaturn to break the chip Continue forward for a couple of turnsand then reverseasbeforeContinue todepthor through theworkpiece by continually tapping a couple of turns reversingandcontinuingforwardThisshouldclearthechipsandpreventthetapfrombreakingIfthetapgetshardtoturntakeitrightoutoftheholetoclearanyswarfaddsomemorelubricantandcontinuetappingA set of hand taps will normally comprise a taper tap a

secondtapandaplugtapUsuallyyouwillstartaholewithataper tap This is a tap where the outside of the thread isreducedtowardsthepointbygrindingitonataperThistypeoftap can be used to start the hole but if the hole goes rightthrough the work it may be possible to screw the tap rightthroughtheholesoformingafullthreadrightthroughIfthetapertapistooshortorifyouaretappingablindhole

youneedtofollowthetapertapwiththesecondtapwhichhasmuch lessofa taper In fact itonlytapersrightat thestartofthetapTheplugtapisfinallyusedusuallytofinishoffablindhole

Theplugtaphasnotaperonitjustashortlead-inontheendBetween the three you should be able to tap themajority ofholesintheworkshopWhentappingblindholesitisbesttoworkoutthedepthand

fromtherethenumberofturnsneededforthetaptoreachthebottomoftheholeAsanexamplesaytheholeis9mmdeeptothepointThe tapenters2mminto theholebeforestarting tocutSo9mmless2mmgives7mmThepitchofthetapis05mm7mmdividedby05equals14sothenumberofturnstothebottomoftheholeis14Inpractice12or13turnswillbethemaximumneededWhen tapping blind holes make sure that all swarf is

removedfromthebottomoftheholebeforestartingtotap

Selectionoftapholders

HoldingTaps

TherearetwomaintypesoftapwrenchthehandtapwrenchwhichisdesignedtobeheldwithbothhandsandtheTeetypetapwrenchwhichoncestartedcanoftenbeusedone-handedTapsusuallyhaveeitheracentreholedrilledintheshankor

theshankisgroundtoapointThismeanswecansupportthetapfromthetailstockeitherbyusingalathecentreorbyabitofbarinthetailstockchuckwithafemalecentreinitTeetypetapwrenchesoftenhaveafemalecentreintheendandcanbesupported on a running centreWhen the tap is supported bythe tailstock at one end and the hole in theworkpiece at the

otheritmustbeinlinewiththeholeintheworkpiece

Machinetap

MachineTaps

Themaintwotypesofmachinetaparethespiralpointandthespiral flute The spiral point pushes swarf downwards throughthe hole while the spiral flute pulls the swarf out of the holeSpiralflutetapsaremuchweakerthanspiralpointtapsandintheory should not be used for tapping by hand However inpractice you can often get away with hand tapping using aspiralpointtapifyouareverycarefulIneithercasethetapisdesigned for continuous rotation swarf being automaticallycleared so the regular reversal as with a hand tap is notnecessaryIf you are careful you can probably get away with using a

hand tap under power but only do this with a hand-held tapholderwhereyoucanquicklyletgoifthetapstartstostickYou can also getmachine taps thatwill cut a thread under

powerbyscrewingthroughthejobwithoutstopping

Spiralflutetap

SpeedsforTapping

Tappingspeedsshouldbe low lowbackgearspeedshouldbefineWhenyouhavetappedtheholetodepthorrightthroughtheworkpiecestopthelatheandspinthetapoutbyhandThiswillbequickerthanreversingthelathe

ThreadingfromtheTailstock

For small taps you can use the sensitive drilling attachment(seeChapter11)orifthetapislargeryoucoulduseaslidingtapholderThiscanbeassimpleasachuckmountedonataperat one endwith a parallel hole through the chuck shank ThechuckthenslidesonabarheldinthemaintailstockchuckForlargetapsyoucanuseatommybartostopthetapholderfromturningbutthetommybarshouldnotbesolongastofoulthelathebedoranyotherpartofthemachineifyouhavetoletgoInfactitisfarsaferifyoudonotusethetommybartothreadunderpower

DIES

Dies also come in carbon steel andHSS versions The outsidediameterofadieoftenvarieswiththesizeofthethreadbeingcutalthoughthediameterwillbetooneofasetstandardDiesusually have themakerrsquos name and the thread details on thefrontof thedieThis is theside that ispresented to theworkThediewill havea short lead-in if this isnot requiredon thefinishedthreadyoucanreversethedieanditwillcleanuptoashoulder

SlidingtapholderSlidingdieholdersarealsoavailable

When cutting a thread especially a small one it pays tomaketheinitiallengthofthreadlongerthanthatrequiredThisissoyouhaveabitat thefronttoplaywithtogetthethreadright Then you can part off the excess length leaving a goodthreadoftherequiredlengthDies are usually split so you can adjust them to cut a size

threadIdeallyyoushouldhaveadieholderforeachdiesoyoucansetthedietocutsizewithouthavingtoresetiteverytimeyouchangethedieThedieshouldbesetsothatitcutsasizethreadinonepassDie nuts are often hexagonal in shape They are used to

cleanupanexistingthreadthat isdamagednot tocutanewthreadfromscratchFor each thread you are going to cut you should make a

home-madegaugetappedwithyourowntapWhenyoucutthethreadanditfitsthisgaugeyoushouldthenhaveagoodbutnottightorloosethreadYoushoulduseatailstockdieholderwithaslidingbodywhen

threadingfromthetailstockasthiswillholdthedietruetothethreadIdeally the tailstock die holder should be knurled and also

haveatommybarholeforeaseofuseThe speed for threading with a die in the lathe should be

quitelowamaximumof60rpmshouldbefineformostjobs

SCREWCUTTINGATHREAD

Whilecuttingathreadwithtapsanddiesisperfectlyadequatefor most applications the ability to cut an accurate screwthreadbyusingthelatheisaveryusefulfacilitytohaveIfthethread is large or non-standard taps and dies may not beavailable or they may be so expensive as to be out of thequestionforuseintheamateurrsquosworkshopVariouspitchesofthreadcanbecutbythesimpleexpedient

of changing the configuration of the change gears or alteringtheleversonthescrewcuttinggearboxifoneisfittedWewillconcentrate on a lathe with change gears if you have ascrewcutting gearbox please refer to the manufacturerrsquoshandbookMost lathes that youwill comeacross are likely to have an

imperialpitch leadscrewThiswillbeapitchofsomany teethper inch (TPI) Typically this will be 4 or 8 TPI although otherpitchesareavailableForourexamplewewillbeusingalathewithan8TPI leadscrewandasetofchangewheelscomprisingthefollowingnumbersofteeth2times202530353840455055606570and75

SETTINGUPTHECHANGEGEARS

Letrsquostakeatypicalthreadpitchof20TPIForeveryturnofthemandrel the leadscrew needs to move forward 120in Thismeans we have to set the change gears so the mandrel toleadscrewturnratio iscorrect Inpracticethemandrelgear islikely tobe20 teethand this is unlikely to change nomatterwhat thread we are cutting This means we will change theleadscrew gear which has to have the correct ratio to themandrelTheTPIwewishtocutis20usingaleadscrewwithapitchof

8TPI20dividedby8givesusaratioof251Thismeansthatthe mandrel gear needs to rotate at 25 times the leadscrewgearAsthemandrelhas20teeththeleadscrewgearneedstobe25times20teethwhichisa50toothgearInpracticea20toothgearanda50toothgearmaybetoosmalltotransferthedrive from the mandrel to the leadscrew and intermediategear(s)willneedtobeusedThese gears are called idler gears and they can have any

number of teeth Youmay think these idler gears change theratio of the mandrel to the leadscrew but they do not Theysimply transfer the drive from the mandrel gear to theleadscrew and the ratio stays the same This concept can behardtograspsoIwilltrytoexplainitsimplySay the mandrel gear does one turn This makes the idler

gearorgearsmoveexactly20teethandthisinturnmovestheleadscrewgearexactly20teethAsyoucanseetheratiodoesnotaltertheleadscrewgearmoves20teethforevery20teeththemandrelgearmovesandtheratiostaysthesameThistypeofset-upisknownasasimplegeartrain

Simplegeartrain

Compoundgeartrain

Letuslookatanothercommonthreadpitch32TPITheratioofleadscrewtoTPIis41(8times4=32)Sotheleadscrewgearneeds to be themandrel gear 20 teeth times 4 = 80 teethLookingattheavailablegearswedonrsquothavean80toothgearThismeanswewillhavetouseadifferentmethodtogetour41ratioWithamandrelgearof20teethwecouldusea40toothto

give us a ratio of 21 We are now halfway there but needanotherpairofgearswitha21ratioWedohavea30anda60

toothgearsothiswouldgiveusoursecond21ratioWecouldnot set these gears up as in the previous example howeversince the two intermediate gears would just act as idlers andtheratiowouldbe2150percentoutfromwhatisrequiredWhatwewouldhavetodoismountthe40toothandthe30

tooth gears on the same spindle so they rotate at the samespeedaseachother(The20toothgearmustdrivethe40toothgearandthe30toothgearmustdrivethe60toothgearinthisorder)Thiswouldgiveusthecorrect41ratiothatweneedAswehavemountedtwogearsononespindlethisisknownasasinglecompoundgeartrainDependingonyourlatheyoumayneedanidlergearbetweenthe30toothgearandthe60toothgearAgainthiswillnotalterthegearratiosYou can also have double compoundgear trainswhere two

lots of gears are mounted together on two spindles This istaking us into complicated territory however and I will referreaders to the screwcutting chart provided for their particularlathe Ifyour lathedoesnotcomewithascrewcuttingchartasearchon the Internet should findone that you candownloadandprintoutThemost likely application of double compound gear trains

would be to cutmetric threads with an imperial leadscrew orimperialthreadsover60TPII have tried to keep this explanation of setting up

screwcutting gears simple and the maths to a minimum Theexplanationgiventogetherwiththescrewcuttingchartforyourlatheshouldbemorethansufficienttogetyougoing

ExternalscrewthreadtoolmadefromaCoventry

diechaser

CUTTINGTHETHREAD

The speed for screwcutting should be about mid-back gear ifyouhaveitpreferablysomewherearound30ndash40rpmatmostTherearetwomainmethodsofscrewcuttinginthelatheThe

firstoneinvolvesthetopslidesetparalleltotheworkandintheothermethodthetopslideissetonanangletothework

Externalsinglepointscrewthreadtoolsettinggauge

Cuttinga20TPIThreadwiththeTopSlideParallel

For a 20 TPI Whitworth thread the pitch is 0050in and thethreaddepthisaconstant064ofthepitchsothethreaddepthis 0050 times 064 = 0032in This is the depth the cross slideshouldbewoundinWhilethedepthofthreadis0032inyoualsoneedtomove

the top slide forwardat eachpass Fora standardVee threadthisneedstobehalfthein-feedofthescrewcuttingtoolsoyoumovethecrossslideinby0010inandmovethetopslidealongbyhalfthis0005in

Cuttingascrewthreadwiththetopslidesetparalleltothelathe

Cuttingascrewthreadwiththetopslidesetatanangletothelathe

Theendresulta20TPIfinishedthreadbeforetidyinguptheendandundercutting

Cuttinga20TPIThreadwiththeTopSlideatanAngle

This angle will vary according to the thread being cut but itshouldbeabout1degree less thanhalf the includedangleofthethreadforaWhitworththreadof55degreesforexampletheangleshouldbehalfof55degreesminus1degreegiving265degreesNotethattheangleistakenwiththetopslidesetat90degreestotheworkWiththetopslidehandlefacingyou(at90degreestohowit isnormallyused)rotatethetopslidethe required number of degrees (265) to the right Beginnersoften rotate the top slide 265 degrees to the left from thenormalpositionwhichwouldgivean included threadangleof127degreesThisisclearlywrongBecausethetopslideissetonanangleyouwillneedtofeed

thetopslideinfurtherthanifthetopslideissetparalleltothelatheYoucan findthe increaseddepthof threadbyusingthefollowingformula

c=bcosineofA

whereAistheanglecalculatedathalftheincludedthreadangleminus1degreegiving265degreesb is thedepthof thread(forWhitworththreadsthisis064timesthepitch)andcisthecalculatedangulardepthofthreadFor a 20 TPIWhitworth thread the pitch is 0050in and the

threaddepthisaconstant064ofthepitchsothethreaddepthis0050times064=0032inThecompensateddepthofthreadisthen0032individedbythecosineof265degrees=00357

UsingtheThreadCuttingIndicator

With an 8 TPI leadscrew if the thread being cut has an evennumber of threads the leadscrew can be engaged at anypositionof the threadcuttingdial indicator If the thread isanoddnumberyoushouldusethesamenumberoranyalternatenumberthatisoneorthreetwoorfourForthreadswithahalfpitch always use the same number For metric threads orpeculiar numbers do not disengage the clasp nuts withdrawthescrewcuttingtoolandreversethemotoruntilthetoolgoesback to the start If the thread is an exact multiple of theleadscrewtheclaspnutscanbeengagedatanypositionIfindoubtalwaysengageatthesamenumberoneIttakes

verylittletimetotraversetheextradistancerequiredFor leadscrews other than 8 TPI please refer to your lathe

manual

AcknowledgementsandUsefulContacts

I would like to thankMy TimeMedia Ltd (Publishers ofModelEngineer and Model Engineersrsquo Workshop) Ken Wilson TonyJeffreeandTranswavePowerCapacitorsLtdfortheuseoftheirphotographs

USEFULCONTACTS

UnitedKingdom

ArcEuroTradeLtd10ArchdaleStreetSystonLeicesterLE71NATelephone01162695693Fax01162605805EmailinformationarceurotradecoukhttpwwwarceurotradecoukSuppliersofmachinetoolsandaccessories

ChesterMachineToolsHawardenIndustrialParkHawardenChesterCH53PZTelephone01244531631EmailsaleschestermachinetoolscomhttpwwwchestermachinetoolscomSuppliersofmachinetoolsandaccessories

CowellsSmallMachineToolsLtdTendringRoadLittleBentleyColchesterEssexCO78SH

ModelEngineerwhichcurrentlyappearseveryfortnighthasbeenpublishedcontinuouslysince1898Itismainlyaboutmakingprecisionmodelsbutoftenincludestechniquesforturninginthelathe

I would like to pass on some of this knowledge This bookMetal Turning on the Lathe is the first of three for CrowoodPressonaspectsofworkshopengineeringitwillbefollowedbyMilling and Introduction to Workshop Tools and TechniquesEachbookwillbeacomprehensiveguideforboththeamateurandprofessionalengineerAlatheisessentialtoallbutthemostbasicofworkshopsIt

enablesyoutoproduceturnedcomponentstoahighdegreeofaccuracywiththeminimumofeffort

ThebasicMyfordmodeltheML7wasmanufacturedformanyyearsTensofthousandsarestilltobefoundingaragesfactoriesandhomeworkshopsaroundtheworldThisistheprototypeML7LatheasrebuiltbyMyfordLtd

ThelaterML7RandSuper7modelswerefittedwithaclutchasstandardThissaveswearandtearontheelectricalcomponentsandthemotorTheyalsohadmorespeedsLaterversionsoftheSuper7canbefoundwithapowercrossfeedTheillustrationshowstheprototypeSuper7latheagainithasbeenrebuilttofactorystandardsbyMyfordLtd

TheAtoZofalathe(A)Changewheelguard(B)Countershaftpulleyguard(C)Drivebeltguard(D)Countershaft(E)Belttensionlever(F)

Oiler(G)Motor(H)Tumblergearoperatinglever(I)Headstock(J)Backgearoperatinglever(K)Mandrelnose(L)Left-handleadscrewbearing(M)Leadscrew(N)Halfnutoperatinglever(O)Toolclamp(P)Topslide(Q)Crossslide(R)Saddle(S)Apron(T)Carriagehandwheel(U)Screwthreadindicator(V)Lathebed(W)Rack(X)Tailstock(Y)Tailstockhandwheel(Z)Right-handleadscrewbearing

AnearlyMyfordlatheAlthoughverybasicitcandoalotofusefulworkintheworkshopespeciallyiftimeisspentonmakingafewsimpleaccessories

This book will show you how to use the lathe safely andeffectively in your workshop but first you should ensure thatyou are familiar with the main parts of the lathe and theirterminologywhichmaybefoundonpage9Chapter1ofthisbookisaboutchoosingalathewhatsizeof

lathe to buy the different types available desirable featuresandwhetheryoushouldbuyneworsecond-handChapter 2 covers installing a lathe how to lubricate it and

maintain it in good condition and advice on general safety inyourworkshopwithparticularemphasisonhowtousea lathesafelyChapter3will lookatthematerials fromwhichcuttingtools

aremadeaswellastheirbasicshapeandgeometryThenwe

willlookatselectingsuitablespeedsandfeedsChapter 4 dealswith sharpening lathe tools andhow to set

themupinthelatheChapter 5 covers the different types of chucks how to use

themandsetworkupaccuratelyinthemChapter 6 teaches you basic turning between centres and

then introduces turning with the work mounted on the lathefaceplateChapter7isaboutholdingworkinacolletandhowyoucan

make and use several different types of mandrel forworkholdingChapter 8 explains how to turn a taper using the top slide

theuseoffixedandtravellingsteadiesandmakingaformtoolChapter9explainshowtousedrillsandreamersinthelathe

includinghowtoselectthecorrectspeedsandfeedsChapter 10 shows the different ways to bore holes in the

lathewiththeworkheldinachuckmountedonthefaceplateorheldonthecrossslideChapter 11 explains how to use knurling tools and radius

turning tools as well as making simple form tools and basicproductionmethodsChapter 12 shows you how to use taps and dies to cut

internalandexternal threads in the lathe Italsoexplainshowto set upa simplegear train and cut a screw threadwith thehelpofascrewcuttingdialindicator

1BuyingYourFirstLathe

WHATSIZEOFLATHEDOIREQUIRE

ThefirstthingtoconsiderwhenbuyingalatheisthesizeoftheworkthatyouwanttodoWhatisthelargestdiameteryouwillwanttoturnonitandwhatisthelongestlengthyouwillneedtoturnA3frac12times18in(90times457mm)lathewillallowamaximumdiameterof7in (178mm) tobe turnedover the lathebed thelatterfigureisknownastheswingInpracticethoughthisisatheoreticalmaximumas it is stillnecessary toholdandclampthe article being turned The swing over the cross slide isusuallymuchsmallertypically2in(50mm)Many lathes however aremanufacturedwith a gapbed at

the headstock end to enable short items of a large diametersuchaslocomotiveortractionenginewheelstobeturnedLathes are also sometimes available as standard and long

bed lathes The long bed lathe as the name suggests allowslongermaterial to be turned within the capacity of the latheWhen turning longermaterial the diameter will be limited bytheswingoverthecrossslideThiswillbealotsmallerthantheswingoverthebedIfbuildingamodelsuchasatractionengineoralocomotive

the deciding factor for the size of lathe is likely to be thediameterof the largestpairofwheels thatneed tobe turnedBefore deciding on the size of lathe required you shoulddetermine the size of the largest diameter and the longestlength of material that needs to be turned Another factor indeterminingwhat lathe tobuy is theavailabilityof sparesand

accessoriesisthecompanystilltradingwillitstillbetradinginthe future and are there large amounts of secondhand partsandaccessoriesavailablefromtooldealersoroneBay

Atypicalinvertertoconvert240voltssinglephaseto240volts3phase

LATHEELECTRICS

Single phase electric is where the lathe plugs into the mainssupplyinyourhouseThemotorwillhavetheusualliveneutraland earth leads Lathes supplied for factory use usually havethree phase motors and require three live wires each of adifferentphaseThinkofaphaseasan incomingwaveon theseashore three successive waves make up the three phasesneededEachphaseisthesameastheprecedingonebuttheyareoutofsyncandallpeakatadifferenttime

Aforwardreversecontrolboxforaninverter

Convertersandinverters

Youcan runsome3phasemotors fromasinglephasesupplyviaaconverteroraninverterThemotor informationplatewillusuallysay240volts440voltsif it iscapableofrunningonaninverter Inside the motor there will be changeover tags tochange the motor from 440V down to 240V Follow theconverterinverter manufacturerrsquos instructions for furtherinformation It isnotusuallyverycomplicatedto runa240V3phasemotor from an inverter and thiswill give a quieter andsmoother running motor than a single phase supply canprovide This usually requires some simple programmingexplainedintheinverterrsquosinstructionsanditusuallytakesfiveminutestogetthemotorworkingproperly

ThismotorispartoftheinverterpackageshowninthepreviousillustrationNowiringisinvolvedasthemotorleadplugsstraightintotheinverterbox

Theinverterrunsataconstantvoltagebutthespeedofthemotor will change as the frequency is raised or lowered Isuggest limitingyour inverter from full speed tohalf speed sothatthefanstillcoolsthemotorandstopsitfromoverheatingyoucanthenusethebeltstochangethemainspeedstepsasusual(Ifyoumustuseveryslowrunningitispossibletoaddaseparatefansuchasacomputercoolingfantogiveconstantairflow) Most inverter suppliers offer a forwardreverse andspeedcontrolboxthatcanbesetupinaconvenientpositiononthe machine These are well worth fitting for convenience inuse

Thisinverterisdesignedformountingonthefrontofthelathe

While inverters are designed to run only onemachine youcangetconverterstopowermorethanonemachineatatimeDependingonthesizeandpoweroutputconverterscostaboutthreetofourtimesasmuchasaninverterTherearetwomaintypesofconverterRotaryconvertersare

designedtorunmorethanonemotoratatimeThisis ideal ifyouwanttorunmorethanonemachineortwomotorsononemachineforexamplethemainmachinemotorandperhapsanauxiliary motor that drives the machinersquos coolant pump orpowerfeedsystem

Arotaryconvertercapableofpoweringmorethanone3phasemotor

ThesecondtypeisthestaticconverterwhichisdesignedtorunonemotoratatimeThereisofcoursenothingtostopyouusingthestaticconverteronmorethanonemachinebyfittingasuitablefemaleelectricalconnectortothestaticconverterandmatchingmaleconnectorstotheindividualmachinesThiswayyoucanconnectthestaticconvertertoonlyonemachineatatime

Thisstaticconverterissuitableforpoweringone3phasemotorIfyoufitasocketontheoutputhoweverdifferentindividualmachinescanbepluggedintoitoneatatime

Theelectricalloadingonrotaryorstaticconvertersmustnotexceed theirmaximumrating If indoubton the loadcapacityneeded to run your machine(s) you should consult the

manufacturerorsupplieroftheconverter

AnearthleakagetripisidealforquicklyeliminatingamotorwheretheelectricalinsulationisbreakingdownItisusefulfordetectingcertainelectricalearthingfaultsbutshouldnotbeusedasaguaranteeofelectricalsafety

Simpleelectricaltestingandsafety

Whenbuyingasmallsinglephasesecondhandlathetakewithyouanearth leakage testerof the typeused for lawnmowersandothergardentoolsIonceboughtaUnimat3lathetookithomeandpluggeditinItkeptblowingtheearthleakagetripinthefuseboxeventhoughithadworkedperfectlyatthesellerrsquoshouseIsolditonatalossbutthebuyerdidknowtherewasaproblemwiththeelectricsIt is most important that the metal parts of any lathe are

connectedtotheearthwirewhichisinturnconnectedtoearthMake sure that themotor frame is also connected toearthassome motors have dampening rubber mounts that insulatethem from themachine itself If in doubt about any aspect ofelectricalinstallationpleaseconsultaqualifiedelectrician

Acontinuousbedisidealwhenworkingwiththefaceplateorwithcollets

LATHEBED

Thelathebedisthebackboneoftheentirelatheandisthepartthat is mounted on the bench or stand There are two maintypesoflathebedtheplainbedandthegapbedTheplainbedisusuallycontinuousallthewayalongitslengthwhilethegapbedhasas itsnamesuggestsagap in thebedThis isnotaliteralgapbutasteppedsectionthatallowsbiggerdiameterstobeturnedthanyouwouldotherwisebeabletoturnonaplainbed latheThisgap isameansofmakinga lathesmaller thanwouldberequiredforaplainlatheabletoturnasimilarsizeof

componentSome continuous lathe beds have a section next to the

headstock that can be removed to increase the diameter thatcanbeturnedThisfeatureisusuallyonlyfittedtolargerlathessuchasaremostlyfoundinfactoriesSome lathes have hardened beds although most are just

plaincast ironTherearethreemaintypesofbedwayscalledshearstheplainflatbedwithsquarewaysabedwithaflattopand a 60 degree dovetail at each side and a bedwith raisedandinvertedVeewaysOnthelastofthesethetailstockusuallyrunsononesetofVeesand thecarriageonadifferent setofVees resulting in lesswear to themain slidesWidebedsarebetterandmoreaccurateasthelathecarriageislesslikelytotwistonawidebed

Close-upviewofatypicallathebedwithagapAgapbedlathehasalargerturningdiametercapacitythantheequivalentsizedcontinuousbedlathe

Someveryearly lathessuchas thosemadebyDrummondhad a round bed Although they worked well there is noadjustmentforwearinthelathebed

TheMyfordrangeoflatheshasasquareformofbed

ThistypeofbedhasaflattopwithaninvertedVeeateachsideTheVeesareusuallysetat60degreesbutcanvarywithdifferentmakers

The Unimat SL lathe was sold for many years and manysecondhandexamplesarestillavailableThismodeldiffersfrommostlathesinthatithastwosteelbarsasabedThisisnotaproblemhoweverastheUnimatisintendedonlyforverysmallandlightweightmodel-makingworkandthereistheadvantagethatthebedcanbereplacedbyfittingnewbarsWhen buying a secondhand lathe it is most important to

checktheconditionofthebedYouneedtomakesurethebedis reasonably free from dings rust and hacksaw marksHacksawmarksneartheheadstockareoftencausedbysawing

offworkwhile it isheld inthechuckdingsareusuallycausedbydroppingthechuckonthelathebedwhenscrewingitonoroffthemandrelAsimplechuckboardplacedonthebedwhilefittingorremovingthechuckwillprotectthebedItisalsoidealfor protecting the bed when filing or hacksawing work in thechuck

AlathebedwithraisedandinvertedVeesThecarriageusuallyslidesononesetofVeesandthetailstockslidesontheother

AmodernChineselathebedwithaninvertedraisedVeeThecarriageandtailstockusuallyslideonthesameVee

Wear ismost commonly found at the headstock end of thelathe as a result of machining many short components andrelatively few long ones Make sure the lathe carriage isproperlyadjustedattheheadstockandthenrunitalongasfaras you can towards the tailstock The carriage should bereasonablyfreebutnotlooseallthewayalongthebed

OldroundbedDrummondlathesarestillavailablesecondhandThisparticularexampleistreadledriven

AflatbedlathewithsquarebedwayssuchasaMyfordcanbe checked for wear on the lathe bed using amicrometer orvernierCheckovertheworkingpartofthelathebedonwhichthe carriage slides rather than the part that is not used forguidance Check both the width and the thickness of the bedwaysThetailstockshouldalsobeagoodslidingfitonanyguiding

surfaces Wear is most likely to be found on the tenon thatslidesbetween thebedwaysAworn tenoncouldprobablybereplacedbutthereisnotmuchyoucandoifthetenonguidesarewornTheonlyway to fixawornbed requiresacompletebedregrindThisislikelytobeexpensivesoitwouldbebettertolookforanunwornlatheDecentunwornlathesareouttheresincemanymodelengineersmayhaveboughtthemnewfortyorfiftyyearsagoandhardlyusedthem

TheUnimatSLisaverypopularsmalllatheItsbedconsistsoftwosteelbarsthatcanbereplacedveryeasilywithsilversteeliftheygetwornormorelikelywhentheygetrusty

Asimplewoodenchuckboardwillprotectthelathebedfromdingsandhacksawmarks

LATHEHEADSTOCK

Theheadstockisthelargecomponentmountedattheleft-handside of the lathe bed It needs to have good bearings An all-gearedheadwillalmostcertainlyhaveballorrollerraceswhilethe older type of lathe for amateurs may well have plainbearings either phosphor bronze or whitemetal These areperfectlyadequatebutyoushouldmakesurethere isnowearinthemSomelathesalsohaveamandrelthatrunsdirectly inbored holes in the cast iron headstock casting Plain bearingswillbeperfectlysatisfactoryas longasadequate lubrication isused

Close-upviewofaMyfordheadstockonanML7RNotethelargebronzebearingatthefrontTheearlierML7latheshadwhitemetalbearingsalthoughtheC7capstanhadbronzebearingsandahardenedlathespindle

Tocheck forwear in the lathersquosbearings fitachuck to themandrelandputadialtestindicatorontopofthechuckGentlytry levering the chuck up and down by using a steel bar orsimilarheldinthechuckYouarelookingforminimalmovementhereespeciallyonaheadstockfittedwithballraces

CheckingthelathebearingsforwearAnymovementupanddownindicateswearinthebearing

The mandrel is mounted in the headstock and is usuallythreaded to take a chuck or faceplate The lathersquos mandrelshould not move back and forth in the bearings If it doeshowever itwillprobablybepossibletoadjust ittocorrectanyendwise movement The mandrel should not be too stiff butshouldturneasilybyhandWhentestingalathemakesuretheheadstockbearingsare

correctlyadjustedsothatwherepossiblethereisnoplaySeta tool up take a trial cut alonga length of bar and check forchatter If you are using a correctly set tool and a suitablespeedchatterisasuresignofwornbearings

Manylatheshaveathree-orfour-stepdrivepulleyasthesecondstageofthedrivechain

POWERDRIVE

Manylatheshaveathree-orfour-steppulleyonthemandreltotake the drive from a similar pulley on the countershaft Thecountershaft is in turn driven from the motor which is oftenmounted at the back of the headstock and completes theintegral drive system that is so popular on most amateursrsquolathes

Thisparticularlathehasatwo-stepmotorpulleyandcountershaftwhichdoublestheavailablespeeds

SpeedchartonthebeltguardofaMyfordML7Rlathe

AfewlatheshaveaclutchfittedasstandardorasanoptionalextraTheclutchsaveshavingtostartandstopthemotorwhileitisrunningThishelpstostopwearandtearonthemotorandelectricalsystemAdifferenttypeofclutchsystemtheTriLevaspeedselector

wasonlyfittedtoMyfordML7orC7lathesThishasthreeleversfor setting threedifferent speedsDependingon the leveryoudepressyougetahighmediumorlowspeedIfyoupressoneof the levers downwhile another is right down the first leverwilldisengagethesecondsostoppingthemandrelfromgoinground If the lathe is switched off and all three handles aredepressed the mandrel is locked preventing rotation This isusefuliffilingorhacksawinginthelathe

TheclutchisnormallymountedinsidethelargecountershaftpulleyItisusuallyoperatedbyaleverattheright-handsideoftheheadstockattachedtoapushrodthatpassesrightthroughthecountershaft

TheMyfordTriLevaattachmentwillonlyfitML7andC7lathesandisnotsuitableforML7RorSuper7lathes

Therehasbeenatrend inrecentyearstodoawaywiththecountershaftandpulleysystemandtoreplacethemotorwithavariable speed one with an electronic controller This isacceptable except that at low revolutions it does not providethe torque that can be obtained from a countershaft systemThereisalsothedisadvantagethatthereisnowaytodrivethelatheifthecontrollercircuitboardfailswhereasyoucanjustfita new one if the belt breaks The board could of course befixed provided that a circuit diagram is available and theelectronic components can be identified Sometimes thecomponents are marked with internal house numbers ratherthan commercially recognized part numbers that can beorderedasareplacementfromacatalogueSomeboardsmighteven have the identification marks removed to make repairsalmostimpossible

ThethreadedendofalathemandrelisdesignedsothatthechuckbackplaterunstrueIfthechuckmountingfaceofthebackplateismachinedinsituthechuckshouldruntrueaswell

CHUCKMOUNTINGSYSTEMS

The threaded lathe mandrel nose is not by itself a suitablelocationforachuckorfaceplatesothenoseisusuallygivenaturned register on which to locate the chuck The chuck isscrewedrightontothemandrelovertheregisterandbuttsuptoaturnedcollartokeepthechuckrunningtrueTheothersideof the mandrel collar butts up against the main headstockbearingwhichusuallyactsasathrustfaceThemandrelisusuallyboredthroughandmachinedtotakea

MorsetapercentreforturningbetweencentresDonotputyourfingerineitherendofthemandreltocleanitwhilethelatheisrunningAneasywaytocleanthetaperintheheadstockiswithabottlebrush often sold in chemists to cleanbabiesrsquo bottlesAnalternativeisasoftfeltshotgunbrushdonotuseonemadefromwire

ThislathehasaplainregisterAccuracyreliesonthelathechuckbeingagoodfitontheregister

There are various systems of chuck mounting in useespeciallyon the larger lathesTheproblemwith thescrew-ontype with a register mentioned above is that the chuck orfaceplatecanunscrewwhenthelatheisrunninginreverseTheonly timeyoushould run this typeofmandrel in reverseveryslowly and without taking a cut is if you need to return thescrewcuttingtooltothestartofthethreadyouarecuttingAlternativespindlenosescanbeaplaindiscwitharegisterto

boltthechuckontooracamlockwherethechuckisheldontightlybyturningstudstolockthechuckontothemandrelTheplain discwith register relies on having chuckswith amatingregistertoworkproperly

AnAmericanstandardCamLockchuckmountingbackplateandCamLockchuckplatefittedtoachuckTheyareusuallyfittedtolargerindustriallathes

TheAmericanDstyleCamLocksystemeithertakesachuckor faceplate directly or it has a backplate that can have aregisterturnedonittosuittherequiredchuckAlthoughmanylathe mandrels with Cam Lock fittings have six holes thematchingchuckorfaceplateoftenhasonlythreelockingpinsThe advantage of both of the last two systems is that they

canberuninreversewithoutthechuckcomingoffthemandrel

Theleadscrewisdrivenfromthemandrelviaageartrain

SCREWCUTTINGGEARS

The left-hand end of the mandrel will often have a gearmountedonittodrivethechangewheelgearsandleadscrewThe mandrel gear usually drives a pair of gears called

tumblergearswhicharemountedona leveratthe leftoftheheadstock The direction of the leadscrew can be changed bybringingeitheroneortheotherintogearbyraisingorloweringaleverThereisusuallyacentralneutralpositionwhereneithergearisinmeshThissaveswearonthelathechangewheelsandleadscrew bearings as well as reducing noise while workingMandrelandtumblergearswillbediscussedfurtherinChapter12whenwesetupascrewcuttinggeartrain

A set of changewheels usually comprises about a dozengearsbutthiscanvarydependingonthemanufacturerThesechangewheels which take the drive from the tumbler gearsdown to the leadscrew are mounted on moveable studs toensurethegearsareinmeshwitheachotherDependingonthenumber of gears in the train the leadscrew will turn eitherclockwiseoranti-clockwiseThedirectionof the leadscrewcanbe reversed using the tumbler gears to enable right-hand orleft-handthreadstobecut

Oftentherearetumblergearsinthegeartrainthatcanreversethedirectionoftheleadscrew

YoucanusuallysetthegearstocutaveryfinepitchsothattheleadscrewactsasaselffeedwhenturningfromthesaddleIf you anticipate the need to do any screwcutting check thatthesuppliedscrewcuttinggearswilldotherangeofpitchesyourequire It has been known for certain lathes to be unable tohandle somecommonpitches a typical examplebeing26TPI(teeth per inch) A pitch of 26 TPI is often needed to repairmotorcycles and bikes made before the introduction ofmetrication

MakesurethatafullsetofchangegearsisincludedwiththelatheIfnottheyarereadilyavailablesecondhand

LEADSCREW

The leadscrew ismounted at the front of the lathe there areusuallybearings to support the leadscrewateitherendof thelathe bed It is used tomove the lathe saddle along the bedeither for a self acting feed or for screwcutting Some lathesalso have a graduated handwheel mounted at the right-handendoftheleadscrewforturningthemandrelbyhandSome of the larger lathes also have a separate feed shaft

whichisusuallyaplainroundshaftwithakeywaycutalongittodrivethesaddleusingafinefeedThissaveswearandtearontheleadscrewwhichisthenonlyusedforscrewcutting

Mostleadscrewscanhaveagraduatedhandwheelmountedontheright-handendoftheleadscrew

SCREWCUTTINGFACILITIES

Ausefulfeatureonanylatheistheabilitytocutscrewthreadsof different pitches Leadscrews come in different pitches acommon one being 8 TPI but many variations are fitted todifferent lathes including leadscrews with a metric pitch It isawkward tomachinemetricscrewswithan imperial leadscrewandviceversaSometimesmetricconversionsetsareavailablebuttheycanbehardtofindareusuallyexpensiveandrequirethe lathe to be changed over often using 127 tooth gearwheels This figure is derived from multiplying the metricequivalentof1in(254mm)byfivea127toothwheelisthusadirectconversiontoametricthreadonalathewithanimperialleadscrewA127 toothgear isusuallyvery large if itmatchesthepitchoftheremainingscrewcuttinggearsbutyoucouldusesmallergearswitha smallerDP (diametralpitch)but stillwith127 teeth Youwould also need amatching gear of say fiftyteethtogiveyoua2541ratio

Thislathehasbothaleadscrewforscrewcuttingandadriveshaftforthesaddleandcrossslidefeeds

Ascrewcuttingdialindicatorusuallymountedtotherightofthe carriage is a useful feature This is a small dial withdivisionsmarkedonitmountedonashaftTheotherendoftheshafthasagearthatmesheswiththeleadscrewandmakesthedial go roundWhen the clasp nuts are engaged the carriagemoves and as the gear moves at the same speed as thecarriagethedialstopsgoingroundWhen you engage the clasp nuts on the leadscrew the

positionwhereyouengagedependsonthepitchofthethreadbeing cut Some thread pitches allow you to engage at anydivision of the dial while others need to be engaged at aparticularpositionof thedialTheuseof thescrewcuttingdialindicator will be covered in Chapter 12 When using the finefeedyoucanengagetheclaspnutsatanymarkedpositiononthedialsoavoidingweartotheclaspnuts

AtypicalscrewthreaddialindicatorThisoneisengagedanddisengagedbylooseningtheboltandengagingthedrivegearwiththeleadscrew

LATHESADDLEANDAPRON

The saddle is thepart that slides on top of the lathebedandusually has the cross slide and top slide mounted on it Theapron ismounted to the frontof the saddleYoushouldmakesure there isnoplay in the saddle either sidewaysorupanddownandthatittravelsfreelyfromoneendofthelathebedtotheotherwithnotightspotsAtthefrontnearesttheoperatorthereisusuallyapairofclaspnuts(thesearesplitnuts)Thesecan be engaged or disengaged from the leadscrew forscrewcuttingormovingthesaddlealongwiththeleadscrewOncheaper lathes there is usually a solid nut that cannot bedisengaged

ThelathesaddleslidesalongthelathebedTheapronisboltedtothefrontofthesaddle

There is often a rack at the front of the lathe bed thatmatches upwith a handle and gears on the lathe apron Thiscan be used to move the carriage along the bed withoutwearingouttheleadscrewSomelatheshavethecarriagefeedwheel on the right but others have it on the left where hotswarfcanfallontoyourhandsThecheaperlatheshavenorackandrelyontheleadscrewtowindthecarriagebackandforth

ATee-slottedcrossslidemakesthesmalllathemoreversatile

CROSSSLIDE

On top of the carriage is the cross slidewhich canbewoundbackandforthacrossthelathebedWhenusingthecrossslideforfacingacrosstheworkthecarriageshouldbelockedtostopitmovingalongthebedLathesforamateurusearemorelikelytohaveaTee-slottedcrossslidewhilelargercommerciallathesare unlikely to have this facility The Tee-slotted cross slide isveryusefulespeciallyifyoudonrsquothaveamillingmachineYoucanboltworktothecrossslideformachiningusingacutterinthechuckorforboringworkpiecesthataretoolargetoswinginthechuckZero settingdials aredesirable for both the cross slide and

thetopslideTheyallowyoutosetthedialtozerowhichmakesiteasiertomeasuretheamountyouaretakingoffwithonecutInusewindthetooluptotheworkandtouchonsetthedialtozeroandwind the toolbackoff from theworkYounowknowwherezeroisonthetoolandcantaketherequireddepthofcut

withouthavingtoworkitout

Zerosettingdialsmaketurningandscrewcuttingtodepthveryeasy

Apairofzerosettingdialsreadytofit

LathescanbepurchasedwithimperialormetricfeedscrewsMostmodeldesignsareimperialbutmetricismakingheadwayandthismaywellbethewaytogoBewarelatheswithimperialfeedscrewsandmetricdialsTypically thesewillhavea funnynumber of handwheel divisions rather than a whole numberMostofthelathesyoumightcomeacrossareunlikelytohavea

power cross feed for facing This does notmatter as you caneasilywindthecrossslideacrossbyhandTheonlytimeIhavefound a power cross feed to be of use is when I had to faceacross a faceplate to true it up I have trued up similar sizefaceplatesbyhanditjusttookalittlelonger

Thetopslideismountedonthecrossslide

TOPSLIDE

ThetopslideismountedontopofthecrossslideThetopslideisnormallysetat90degreestothecrossslidealthoughitcanusually be swivelled around to various angles for turning ataperanangleorforscrewcuttingSomeofthecheaperlathesdonrsquothaveatopslideasstandardbutitisaveryusefulfeatureif you can get one The top slide should be able to rotateespecially for screwcutting but the top slide handlemay foulthecrossslideincertainpositionssocheckifthisisaproblemTheturningtoolisusuallymountedonthetopofthetopslideItcan either be clamped on directly usually with packing stripsunderneathorthetoolcanbemountedinatoolholdersuchasathree-orfour-waytoolpostoraquickchangetoolpostWewilllook at tool holding methods in Chapter 4 when discussingsettingupturningtools

TAILSTOCK

The component at the right-hand end of the lathe is thetailstock This usually has a handwheel to feed a drill into theworkbut leverfeedandcapstan-style feedingmechanismsarealso available You can lock the tailstock anywhere along thebed The tailstock has a barrel inside it that can bewound inandouttogivealinearmovementtodrillaholeinworkheldinthechuckThetailstockisusuallyboredtoaMorsetaperoftenof a similar size to the headstock so it can take accessoriessuchasdrillchucksmountedonaMorsetaperItcanalsotakeacentre for turningworkbetweencentres It is important thatboth the headstock and tailstock tapers are free frommarksscratchesandburrs

AlathetailstockwiththebarrelextendedNotethatitisnotusuallyaproblemifthechuckkeyisleftinthetailstockwhilenotinuse

Adjustment is usually provided between the base and themain body of the tailstock to allow for setting the tailstock inlinewith theheadstock Tailstocks canbe self ejectingwherethetool isextractedas it iswoundbackwhilesometailstockshavea throughholeandneeda tapwithabar to remove thetool Handwheel depth graduations for drill drilling to a

particularholedepthareveryusefulbutarenotoftenincludedon the cheaper lathes although industrial lathes usually havegraduatedtailstockhandwheelsThebettermakesoflathehavea lever clamping tailstock arrangement while the cheaperlathesoftenhaveaclampingspanneroranAllenscrewclamp

Allguardsshouldbefittedinplacebeforeoperatingthelathe

MACHINEGUARDS

Thedrivemotorcountershaft(iffitted)andpulleybeltsshouldallbeproperlyguarded It isveryeasy togetcaughtup inanunguardedmachineandtheconsequencescanbequitenastyThis has never happened to me but I have seen someonecaught up in a machine and it was not very nice I dorecommend that you make sure your machine guards arecorrectlyfitted

OTHERDESIRABLEFEATURES

Digitalreadoutsareusefulonalatheastheycanshowyouhowmuch to move the handwheels and how much material hasbeentakenoffTheyarequiteexpensivebutyoucan fit themyourself if youare carefulUnfortunatelymost of the cheaperversionsdislikesolubleoilorothercoolantifyougetitintothereadouthead

Adigitalreadoutsuitableformountingonalathe

Youwillneedtwoslidesoneforeachaxis

A soluble pump for cutting fluid is useful and often comesfittedasstandardonthelargerlathesHoweveratinofcuttingoilandabrushwillbegoodenoughformostworkandthatmaysuityoufine

Solubleoilpumpsandreservoirsarereadilyobtainable

Formostjobsyoucangetawaywithsomecuttingoilabowlandabrush

TheMyfordlsquoNortonrsquostylequickchangescrewcuttinggearbox

A Norton quickchange screwcutting gearbox saves time asyou donrsquot have to set up changewheel trains A gearboxhowever considerably increases the price of the averagesecondhand lathe A Myford Norton gearbox has twenty-fourpitchesandiscontrolledbytwoleversReversingtwogears inthe Myford changewheel train gives the gearbox twenty-fourfine feeds insteadof the twenty-fourscrewcuttingpitchesThegearboxhasa setofgearsarrangedasaconeBysliding thelever along and dropping themaster gear onto the cone youcanchangethegearboxratioandsothepitch

TheconegearsinsideatypicalNortonscrewcuttinggearbox(notanoriginalMyfordone)

SeveraldesignshavebeenpublishedtomakeyourownNortontypescrewcuttinggearboxThisoneisavailablefromHemingwayKits

SPINDLESPEEDS

Thespeed rangeneededona lathedependson thework it is

requiredtodoAgoodrangeofspindlespeedsisdesirablewithnoobviousgapsWithelectroniccontrolthisshouldnotbetoomuchofaproblemIdeally a back-geared lathe would be best but this means

either a good secondhand machine such as a Myford or aBoxford or alternatively one of the larger Asian-made latheswithanall-gearedheadstock

Thisbackgeararrangementisswitchedinandoutbyturningthetoggleonthepulleyandliftingaleveratthefrontofthelathe

Backgearnormallyconsistsoffourgearstwolargeonesandtwosmalloneswhichcanbeswitched inorout toreducethespeedofthelathebyaratioofusuallyabout51dependingonthe maker to enable you to turn large diameter workpiecesThis reduction is also essential on a screwcutting lathe asotherwisethemandrelwillbegoingtoofastwhilescrewcuttingandyouwonrsquotbeable tostop in the rightplaceat theendofthethreadIf buying a back-geared lathe check that both gearwheels

havealltheirteethItisamajorjobtostripdownalatheandfitnewgearwheelsassumingtheyareevenavailableassparesCheckthelatheinallgearrangeswiththelatherunningIfa

back-geared lathe or an all-geared head is noisy it could

indicatewearitwillalsobeanuisanceinyourworkshopasnoonewants to hear a noisymachine runningNoise could be amajorproblemespeciallyifyouhaveneighboursnearbyGearedheadsusuallyhaveawiderangeofspeedsthelarger

industrial lathescangoup tospeedsof2000rpmandsmallerversionsareoftenhigher

Anall-gearedheadonamodernindustrialsizelathe

On the more usual amateursrsquo lathe there is often acountershaft usually tensioned by a lever which tightens upthebeltreadyforuseThemiddlespeedofthecountershaft isusually chosen to be about one quarter of the motor speedMost small lathes have three speeds and the back geararrangement adds another three speeds giving six in all TheMyfordSuper7rangeoflatheshavefourspeedsandbackgearmaking eight speeds but there is also a double pulley on themotor countershaft section making sixteen speeds in allalthoughtheverylowestback-gearedspeedswillrarelyifeverbeusedSomeoftheolderColchesterChipmasterlatheshavewhatis

knownasaKoppVariatordriveThis isavariable speeddrivecontrolledbyadialandthesystemworkswellbuttheVariator

isveryhardtoreplaceifthedrivefails

ThissmallCowellslatheiscapableofdecentworkandatthetimeofwritingisprobablytheonlylathestillbeingmadeinBritain

MOUNTINGTHELATHE

There are three main options for mounting a lathe benchmounting portable or on a stand Ideally a makerrsquos standshouldbeusedformountingamediumto large latheandthestandisoftenanintegralpartof larger lathesAsmaller lathesuch as a Unimat or a Cowell can bemounted on a woodenchopping board or a similar small board These lathes can beputawayinacupboardafteruseThe alternative is a workbench but these are often made

from wood which can expand or contract depending on themoistureintheairWoodisnotagoodmaterialfromwhichtomakea stand for a larger latheas itwill attractmoisture andmayexpandshrinkordistortAmetalstandisabetteroptionWewilllookatinstallingthelatheinChapter2

AnArcEuroTradeC3screwcuttinglathemadebySiegThisisaverypopularentrylevellatheandmanyaccessoriesareavailable

Amedium-sizedscrewcuttinglathesuitableforgardenshedworkshops

SHOULDIBUYNEWORSECONDHAND

Beginnerssettingupaworkshopoftenaskifitisbettertobuyanew lathe or secondhand The preceding pages should have

given some guidance but there are more points to be takenintoconsideration

Alargerindustriallathewithafoot-operatedemergencycut-offswitchandbrake

BuyingNew

Thelistoflathesuppliersincludedatthebackofthisbookwereall in business at the time of writing Most will be willing todemonstratetheirrangeofmachinesattheirpremisesorwhileattendingmodelengineeringexhibitionsPaycloseattentiontomechanical noise the general paint finish and the workingslideway surfaceswhich should begroundDoes themachinehave sharpor roughedges (Handwheelsareespeciallypronetosharpedges)The main thing to consider though is the attitude of the

supplier Were they willing to talk to you and answer yourquestionseitheratanexhibitionoroverthephoneHowlongdo they take toanswer thephonewhenyou ring their servicedepartment Do they know the answer to a simple questionstraightawayordotheyhavetogetbacktoyouIsthemanual

written in English or Chinglish (translated awkwardly fromMandarinorCantonese)There are several suppliers of new lathes inmost countries

aroundtheworldbutthemajorityoflathesaremadeintheFarEastOftensupplierArsquosmachinescomefromthesamefactoryassupplierBrsquostheyarejustpaintedadifferentcolourandhavedifferentnamesandlabelsfittedAftersales service can vary greatly Usually companies that

havebeeninbusinesslongerwillofferbetteraftersalesservicebutotherpeoplersquosexperiencescanbefoundonInternetforumsoratlocalmodelengineeringclubsUsually theAsian lathesare reasonablywellmadebut they

often suffer from having plastic gears instead of metal onesOneortwocompaniessupplymetalgearsasstandardso it isworthaskingiftheirmachineshavemetalorplasticdrivegearsSome companies also offer after-market replacement metalgears

BuyingSecondhand

There aremany good quality secondhandmachines availablebut there is also a lot of worn-out rubbish If possible take aknowledgeable friend with you when purchasing a lathe Becareful when buying at online auctions such as eBay MostsellersaregenuinebutsomearenotNeverpartwiththecashuntil youhavechecked the latheover IhaveboughtoneBaywithoutproblemsbut Iamcarefulwhat IbuyandwhofromAsmall latheforacoupleofhundredpoundsisunlikelytobreakthe bank if it is a bit of a dog but a lathe that costs severalhundredpounds is adifferentmatter ThegreenMyfordML7RpicturedthroughoutthisbookwaspurchasedfromeBayItwasbrand new the motor had never been fitted and it was abargainwhencomparedwiththeretailpriceIdidpaycashoncollectionbutIwouldhavewalkedawayif ithadnotmatchedthedescriptioninanywayWhether purchasing new or secondhand check what

accessoriescomeaspartofthepackageandwhatwillneedto

bepurchasedseparatelyEssentialtoolingcanoftendoublethecost of a newmachine if it is not included in the price whilededicatedtoolingmaynotevenbeavailable forasecondhandbargainlathe

Youshouldnowhaveanideaofthesizeoflatheyouneedthefunctionofthedifferentpartsofthelatheandwhetheryouarebuying new or secondhand In Chapter 2 we will look atinstallingthelatheandsafetyintheworkshop

2InstallingtheLatheandUsingItSafely

If you are buying a new lathe completewith delivery to yourworkshopyoucangostraighttothesectiononsettingthelatheupIfyouarecollectingthelatheyourselfhoweveryoushouldpayattentiontoafewwordsonmovingit

Ifyouhaveroomtomanoeuvreanenginehoistcanbeusedtomovemachineryaroundsafely

MOVINGTHELATHE

MOVINGTHELATHE

When going to collect your lathemake sure someonewill betheretohelpyouloaditortakesomeonewithyouUnlessitisaminiaturelatheitwillbetooheavyforonepersontoliftHelpisalsoneededwhenyougetthelathehomeLiftingthelatheoutofacarcanbeharder than lifting it in It isadvisable tohavethreepeoplewhenunloading twoat theheavyheadstockendandoneliftingthelightertailstockendYoucanrentorbuyanenginehoist fora reasonablepriceand this canmakemovingthemachineeasierIf the machine is a substantial industrial type it would be

besttohireatransportcompanythatspecializes inmachineryremovals Professional machinery removers will usually haveproperlyequippedtransporttomoveheavymachinesThiswillprobablyworkoutcheaperthanattemptingtodoityourselfbutmake sure they have insurance in place in case they damagethelatheoryourpropertyYoushouldalsoensuretheyknowithas to beput in place as required in theworkshop youdonrsquotwanthalfatonofmachinerydumpedonyourdrivewithnowayofmovingitintopositionLathesareusuallytopheavywhenbeingmovedandcantip

overifyouarenotcarefulTheMyfordML7seriesforexampleoftenhasthemotorandcountershaftboltedtothebackofthelathe bed and this type of lathewill tend to tip backwards Asimple solution is to bolt two lengths of wood about 4 times 2in(100times50mm)tothelathefeetOneboltineachendwilldoifyou canrsquot drill holes in the correct position This will stop thelathe tipping backwards and also make it easier to lift IfpossibleyoushouldremovethetailstockThisisoftenaheavylumpofmetalbutitisusuallyveryeasytoslideitofftheendofthelathebedAnyotherlargeobjectsthatcanberemovedandreplacedlaterwillmakethelathelighterandeasiertomove

Twoplanksofwoodboltedtothelathefeetwilloftenturnanunmanageablemassofmetalintoaneasilyhandledmachine

Azerovoltsswitchisessentialequipmentonanymachinetool

Wearoldclotheswhenmovingyourlatheandhaveplentyofold rags to wipe off swarf and oil Lay down old blankets ordecoratorsrsquosheetsinsidethecarandasheetofthickcardboardMDForplywoodtohelpprotectthebootareawhenslidingthelatheintothecar

AsmallishlathecanoftenbefittedintoastandardhatchbackorestatecarYoumayfindhowever thatyouhavetodotwotrips one for the lathe and accessories and another for thecabinetthelathestandsonTosaveawastedjourneyIusuallytrytofitthelathecabinetinfirstIfIthenfindthatthecabinetdoesnrsquotfitIcanstillbringthelatheandtoolinghomeknowingthat Ihave tohireavan tocollect thecabinetbutalso that IhavenothadawastedjourneyIfyouhavetosplittheelectricsforexampletotakethelathe

offthecabinetdrawadiagramoftheelectricalconnectionssoyoucanrewirethelathewhenyougetithomeAdigitalcameraisalsoagoodmethodofrecordingthewiringconnectionsbutIwouldnotrelyonthecameraaloneIf the lathedoesnothaveazerovoltsswitch itwouldbea

good idea to fit one after you get the lathe home They areavailable quite cheaply andare easily fitted If in doubt aboutyourabilitytodoelectricalwiringconsultaqualifiedelectrician

Adjustablefeetareveryusefulforlevellingupthelathe

SETTINGUPTHELATHE

Somelathesusuallythelargerindustrialoneshaveanintegral

bedandcabinetThelathecanbesettotruewithjustshimmingunderthefeetorbyadjustingthefeetOther lathes may need to be mounted level and true to

ensureaccuracywhenturningSetthebenchstandas levelasyou can in both directions using a spirit level as a guide Anycheapspirit levelwilldoas longas it isaccurateYoucantesttheaccuracyofaspiritlevelbyturningitround180degreesifitisaccurateitshouldreadthesamebothwaysOnce the stand is reasonably level youcan level the lathe

ThisinvolvesjackingorshimmingupthelatheuntilitistrueinbothdirectionsIfusingawoodenbenchputmetalplatesunderthe feet tospread the loadShimoradjust the latheuntil it isreasonablylevel

Putthespiritlevelonthecabinetrsquoslongitudinalaxisandusetheadjustablefeettolevelthelathe

Insertalengthofbarinthechuckandputadialtestindicatoron top of the tailstock end of the bar Nip the headstock endmounting bolts down first and then tighten down the tailstockendboltsAdjustorshimthetailstockenduntilthereisnosignof movement on the test indicator Next 64repeat theprocedure with the dial test indicator on the front of the barAgainyouare looking fornomovementCheckbothdirectionsagainmakingsurethereisnomovementeitherhorizontallyorverticallywhenyoutightenthelathedownAdjustorshimuntil

there is no movement in either direction when the lathe isclampeddownAslongasthebedisnottwistedthelathebedshouldnowbetrue

1Insertapieceof⅛in(3mm)packingunderthespiritlevelatthetailstockendThiswillresultinarunonthedriptrayandalltheoldoilwillruntotheendofthelathemakingiteasiertocleanup

2Placethespiritlevelonthecabinetcrossaxisandusetheadjustablefeettolevelthelathe

3Putthespiritlevelonthelathecrossaxisattheheadstockendandlevelitasbestyoucan

4Putthespiritlevelonthelongitudinalaxisandlevelalongthelathe

5Testthetopofthebarthereshouldbenomovementwhenthelatheisclampeddown

6Testthefrontofthebaragainensuringthatthereisnomovementwhenthelatheisclampeddown

Alignthetailstockbyusingadialtestindicatorintheheadstock

AligningtheTailstock

NowweneedtosetthetailstockinlinewiththeheadstockDothisbyputting thedial test indicator into theheadstockchuckandtestthetailstockboreAdjustthetailstocktowardsthefrontortothebackofthebeduntilthetestindicatorreadstrueandtighten theclampscrewsA slightdifference inverticalheightwillnotbetheendoftheworlditjustmeansthereisprobablysomeweartothebaseofthetailstockcastingbutthereshouldbenovariationfromfronttobackinthehorizontalalignmentPutalongbarbetweenthecentresandtakealightcutalong

it using a fine power feed Run along the bar a couple moretimes at the same setting to remove any push offWhen youmeasure thebar it shouldmeasure the sameatbothends Ifthe bar is larger at the tailstock end you need to reduce theheightofthebedatthefrontofthetailstockslightlyIfsmalleratthetailstockendyouneedtoreducetheshimatthebackofthe tailstockend Itprobablywonrsquotneedmuchadjustmentasslightadjustmentstotheshimoradjustersatthetailstockendwillsoonbringitintoline

Usingatestbartocheckforparallelturning

LubricatingtheLathe

You should follow the manufacturerrsquos recommendations forlubrication Usually this is thin oil for the headstock oftenhydraulicoilandslidewayoil forthemovingpartsLubricationshouldbedoneregularlyIfthelatheisfittedwithasightfeedoileritshouldshowoilinitAdjustablesightfeedoilersasusedonMyfordandsimilarlathesshouldbeadjustedsothattheoildripswhen the lathe is running but does not dripmuchwhenthe lathe is stopped The slight vibration when the motor isrunningisusuallyenoughtocausetheoiltodripToomuchoilisbetterthannotenoughoilisfarcheaperthannewbearings

Atypicaldrip-feedlubricator

UseanoilgunonalltheoilnipplesYoucangetaroundthetendencyfortheoiltogoeverywhereexceptintothenipplebyputtingapieceofwritingpaperoverthenippleandthenusingthe oil gun as normal The paper will stop the oil squirtingeverywhereThemandrelbackgearalsoneedstobelubricatedWheninusethemainbackgearisrunningontheoutsideofthelathemandrelandneedstobelubricatedoftenoritwillgethotandwearChangewheels should be lubricated with oil not grease If

youusegreaseswarfwillsticktothechangewheelsandcauseunnecessarywearTo stopswarf running through themandrelanddroppingoutontothechangewheelsputawinebottlecorkor similar into the left-hand end of the mandrel This willeffectivelystopanyswarfgettingthroughtothechangewheelsOil the saddle and cross slide and also the nipples on the

tailstock Make sure oil is showing at the edge of the slidingsurfaces A squirt of oil on the cross slide and topslide feedscrew bearing is needed as well Check the manufacturerrsquosinstructions for lubricating the rest of the lathe Follow themotormakerrsquosrecommendationforlubricatingthemotorTrytoavoidusingWD40onthelatheWhileitisanexcellent

lubricantwaterdisplacerittendstodiscolourthelathebed

Useabitofpaperundertheoilguntostoptheoilsquirtingeverywhere

AvoidingtheRustFairy

Rust canplayhavocwith a lathe quickly turning thebedandother parts into a brownmess Various sizes of plastic coverssuitable forcovering lathesareoftensold foruseasbarbecuecoversinDIYstoresAplasticlathecoverwillhelptokeeprustatbaybutmoreneeds tobedoneAbagcontainingsilicagelplacedundertheplasticcoverforexamplewillabsorbexcessmoisturesilicagelcanbeboughtverycheaplyoneBay

SilicageliseasilyobtainablefromeBay

Alternatively you can buy a vapour phase inhibitor forprotecting the lathe The vapour phase inhibitor chemical issuppliedonafeltpadinsideaplasticpotThechemicalformsaprotectivelayeroneverysurfaceBecauseitisavapouritwillfind its way into every cranny and is also used for protectingtools and accessories in tool cabinets and drawers It usuallylasts for twelvemonths ifenclosedby theplasticcoverSomemachinetooldealersareabletosellsuppliesofthisproductinsmall ready to use containers rather than in industrialquantitiesAlwayscleanthelathedownafteruseswarfwillsoonrustif

leftonalatheasitwillprobablybecleanfromturningandwillnotbeprotectedbyoilTheuseofanovencookingtrayunderthe lathe bedmakes it easy to remove swarf at the end of aturning session The tray also helps to retrieve a parted offcomponentora lost screw froma tipped turning toolAnotheralternativeistocoverthelathechiptraywithnewspaperwhenyouhave finished turning remove thenewspaper screw it upandthrowitawayWhenfittingachuckorfaceplatetothelathemakesureyou

cleanthemandrelthreadtheregisterandthefaceYoushouldalso clean the mating threads the bore and the face on thechuckorfaceplateYoucancleanthethreadandboreeasilybyusing two toothbrushes bolted back to back with spacers inbetween Make sure the Morse tapers in the headstock andtailstock are cleanbefore fitting aMorse taper accessory TheMorse taper to be fitted should be free from scratches burrsandbruisesIt is good idea tomake a chuck board for usewhen fitting

chucks to a lathe or removing them This is a piece of wood(plywood will do) that sits on the lathe bed while you arescrewingthechuckonandoffThechuckboardwillprotectthelathe ifyoudrop thechuck It canalsobeused toprotect thelathebedwhenyouarehacksawingorfilinginthelatheIf you keep your lathe clean and lubricate it regularly it

shouldlastalifetime

AlargetraywillcatchmuchoftheswarfandtheholeslettheoildrainawayUsenewspapertosoakuptheexcessoil

SAFETYINTHEWORKSHOP

RememberyouareresponsibleforyourownsafetySafetyisamajorconcernintheworkshopTherearecertain

thingsyoushoulddoandobviouslythingsyoushouldnotByitsverynatureaworkshopcanbeadangerousplaceallwecandoismakeitassafeaspossiblewhilestillallowingustoworkinit

WorkingAlone

Mostofyoureadingthisbookwillprobablybeworkingaloneinasmallworkshopgarageorgardenshed IfyougethurtyoumaypossiblybeonyourownAsapriorityIsuggestyoutakeamobilephoneintotheworkshopandkeepitinyourpocketTheability to contact your family a friend or the emergencyservicesquicklycouldsaveyour lifeKeepthephoneswitchedoff while in the workshop however as it is an unnecessarydistraction

FirstAid

FirstAid

AFirstAidboxwithcontentsisanecessityandshouldincludeaneye-bathandeyewashYoushouldparticularlylearnhowtostopbloodflowingThereareplentyofwebsitesthatwilltellyouhowtodothisCheckthemoutnowbeforeyougobackintotheworkshop

ElectricalSafety

Checkforearthcontinuitywhilethemachineisunpluggedwithavoltohmmeterfromtheearthpinonthethreepinplugtothemetalpartofthelathe(somepaintmayhavetoberemovedforareadingtotakeplace)Youshouldgetareadingofzeroohmsorabeep if themeterhasacontinuity rangeYoushouldalsobe sure that the electrical sockets on the wall are correctlyearthedIfindoubtconsultacompetentelectricianLightingandelectricheatingshouldbeonaseparatecircuit

tothemachinessoyouwillstillhavelightifthemachinestripoutPlugasmalllightintothemachinecircuitsoyouhavesomelight if the lighting circuit trips out When I go on holiday Ialwaysturnoffthefusetripsforthelightinginordertomakeitmore difficult for intruders to move about quickly Leave thehouse alarm and smoke detectors on (The house alarmmayactivateeighthoursafter theelectricity is turnedoffwhenthebatteryexpires)

Adigitalmultimeterisveryusefulinthehomeworkshop

BeAware

Bementally alert while using the lathe Avoid operations thatmightputyourhandsatriskofenteringthemovingpartsofthelathe Do not operate any lathe while under the influence ofdrugs alcohol or prescription medication that may causedrowsinessorotherwiseaffectyourability to control the lathesafelyDonotattempttoworkonalatheandtalkatthesametimeIfyouhavetotalktosomeoneswitchoffthelathebeforedoingso

KeepItClean

TheareaaroundalatheshouldbekeptfreeofobstructionsThefloorshouldbecleananddrywithanyoilorotherspillscleanedup immediately The lathe should be kept clean and tidyMachinedangerareasshouldbemarkedontheworkshopfloorand observed Workbenches placed near a lathe should be

strongandequippedwithanon-slipsafetysurfacetostoptoolsor other items rolling onto the floor a rubber car mat willsufficeA rubberdoormat on the floorwill allow swarf todropthrough in order to save you getting swarf embedded in thesolesofyourshoes

Asuitablefloormatwillallowswarftodropthroughandhelpkeepyourfeetwarminwinter

LearntoUsetheLathe

Donotuseany lathebeforeyouare familiarwith thecontrolsandareawareofthedifferentwaysofstoppingitThismaybea clutch an onoff switch a No Volts release switch or anemergency stop button I strongly advise fitting a No VoltsreleaseswitchifyourlathedoesnothaveoneAswellasbeingusefulforstoppingthelatheinanemergencyitwillpreventthelathefromstartingupbyitselfafterapowercutIfyouarenotcomfortableworkingwith electrical equipment get a qualifiedelectriciantofittheswitchforyou

StaywiththeLathe

Nevereverwalkawayevenforamomentwhilethelatheyouare using is switched on Switch it off if you are leaving itunattended and only leave the lathe after it has come to a

completestopNeverleavealatheinanunsafeconditionMakesure that you have not left the chuck key in the chuck Thechancesarethatifyouarehalfwaythroughsettingupthelathewhen you return you will forget what you have or have notdoneIfindoubtleaveabignoticeremindingyourselftocheckthatthelatheissafebeforecontinuing

Donotleavethechuckkeyinthechuck

SwitchOffwhenAdjustingtheLathe

Shut off the power supply to the motor before starting anyoperationsrequiringaccesstothelathesuchaschangingtoolsmeasuring work mounting or removing accessories changingspeed and setting up change gears The lathemust be safelystopped Just zeroing a variable-speed drive is not safelystoppingitusethezerovoltsswitchtoswitchthepoweroffaswell

CheckbeforeStartingtheLathe

AlwaysrotateyourworkpiecebyhandtomakesureitclearsthetoolrestsaddleandbedDoublechecktomakesureyourworkis securely clamped in the chuck or between centres beforestartingthelatheBecertainthattheworkpieceturnsfreelyand

isfirmlymountedThespeedofthelathemustbecheckedbeforeturningiton

When turning irregular shapes start the lathe on a low speedandincreasethespeedbyapulleystepeachtimeIfthelatheisbouncingabout lowerthespeedandorbalancethework Ifthe work vibrates stop the lathe and check the reason ThechancesarethatyouarerunningthelathetoofastMeasuringequipment toolingandworkpiecesshouldnotbe

leftona latheastheycanvibrateoff intomovingcomponentsand be thrown around the room Check for loose items on alathebeforeuse

UsetheLatheGuards

NewlatheswillbefittedwithguardsoverthemotorshaftdrivebeltandspindlepulleysTheseguardsshouldalwaysbeinplacebefore using the lathe Any other moving parts should beguardedtopreventanythingfallingontothemovingpartsAlthoughguardsareoften removedbymachinistsprovided

they are constructed from clearmaterials and open and closeeasily theyaddsafetywithout interferingwith theworkbeingdone Guards will at the same time deflect swarf and anycoolantthatisbeingusedGuardsfittedtothelatheshouldnotbe removed while it is in use They should be made fromsuitablematerialandnothavesharpedgesTheyshouldnotberemovedforadjustmentandlubricationofthelatheunlessthisis unavoidable Lathemanufacturers donrsquot usually supply chipguards soaddingoneshouldbeconsideredChipguardswithmagnetic bases are available although they can attract steelswarftothemagnetPutthebaseintoaplasticbagtoaidswarfremoval

UseEyeProtection

Lathes can throw sharp metal chips considerable distancesespecially at high cutting speeds Apart from deep cuts thechipsmay leave the tool red hot cause skin burns and even

burnholes in clothing Youmust use safety goggles or propersafetyspectacleswhileintheworkshopAlwayswearindustrialqualitysafetyglassesfittedwithsideshieldsSpectacleswithoutsafety lenses are not adequate eye protection When theglasses get dirty do not wipe them off as they will becomescratchedWashthemoffunderthetapinstead

TakeCarewhenRemovingSwarf

Do not attempt to remove chips or turnings with your handsAlwaysswitchoff the lathefirstandeitherpull theswarfawaywithalargemetalhookorliftitoffusingapairofglovesIftheswarf is tangled around the lathe untangle it with a pair ofpliersandnotaglovedhandasitwillcutstraightthroughtheglovesandintoyourhandUseadustpanandbrushtoremovesmall chips and swarf from the swarf tray ndash never use yourhandsWhenswarfbecomesstringyandbuildsuponthetoolortoolpostturnoffthelathebeforeremovingit

AvoidLooseClothing

IfyouarenotwearingoverallswearshortsleevedshirtsorrolllongshirtsleevesabovetheelbowsLoosesleevescancatchonrotatingworkandquicklypullyourhandorarmintothe latheObviously though keep your arms protected if hot swarf isflyingaroundSwarf can get inside protective clothing especially collars

(useaclothespegtokeepyourcollartight)pocketsandshoesTostopthesleevesofanoverallcatchingsewelastic intothecuffsorwrapacoupleofthickelasticbandsaroundthecuffstostopthesleevesgettingcaughtupUnder no circumstances wear a necktie when operating a

latheProtectiveglovesshouldneverbewornwhileoperatingalathe Protective gloves may be worn when swarf is beingremovedbuttheymustberemovedbeforeswitchingthelathebackon

UseSturdyFootwear

WearsteeltoecapsafetybootstheyarenotexpensiveandwillhelptoprotectyourfeetfrominjuryifyoudropaheavyobjectonthemThelsquotrainerrsquoversionisparticularlycomfortableDonotallow stringy swarf to fall on the floor as youwill get cuts onyouranklesandmayeventripoverit

AvoidJewellery

Do not wear wristwatches rings or jewellery when in theworkshop as it could catch on a rotating part of the lathe orworkpieceThisalsoapplieswhenmovingalatheintooroutoftheworkshopsincetheycouldcatchona falling lathe IfyourotherhalfcomplainsthatyouhavetakenoffyourweddingringexplainthatyouwouldnrsquotbeabletowearitagainifyourfingerismissingduetoanaccidentLonghairshouldbetiedbackasyoucouldbepulledintothelatheifitgetscaughtintherotatingwork

LiftingintheWorkshop

Back injuries can be caused by incorrect lifting practices It isimportant to bend your legs when lifting rather than bendingyour back A hoist or engine lift should be used to lift heavyitems A stool in theworkshopwill take the pressure off yourlegs and will provide a welcome break after you have beenstoodatthelatheforawhile

Self-ignitingMaterials

If you machine titanium or magnesium which can ignite andburn vigorously keep the accumulation of turnings to aminimum If thematerialdoescatch firedonrsquotusewaterorawater-based coolant as an extinguisher since it will makematters much worse Before starting to machine titanium ormagnesiumfillalargebucketwithdrysandcoveritandkeep

it by the lathe The sand will smother the flames veryeffectivelyYoucouldalsobuyoneofthespecialfireretardantsusedinindustryBeware also of grinding aluminium on the bench grinder

Aluminium and steel filings are the ingredients of Thermite apowerful explosive that can also burn If you grind aluminiumandthenchangeovertogrindingsteeltheredhotsparksareliable to set the steelaluminium mix on fire This is a verydangerous combination ofmaterials and should be avoided atallcosts

SafetywithBarStock

Bar stock should be contained within the headstock and notallowed to protrude from the rear of themandrel I once sawsomeone switchona lathewhenabrassbarwas stickingoutfrom the back of the headstock by about two feet With thelathe running at 2000rpm the bar whichwas aboutfrac34in (19mm) in diameter was bent at right angles and caused theheavy lathe which weighed 1280kg to jump about Luckilysomeone managed to switch the lathe off before any majordamageoccurredItwasnottheoperatorhehadrunwellawayandwasnowheretobeseen

SomeFinalWordsonSafety

Wherever possible the machine height should be adjusted tosuittheuserWearestillusingfifty-year-oldmachinesbutfiftyyearsagothenationwasshorterTheworkplaceshouldbeprovidedwithuniformlightingthat

gives an adequate level of illumination Individual machinelightsarebestThe lathemust be set to operate at the speeds and feeds

recommended for thespecificmetalbeingturned If themetalrotatestooslowlyortooquicklyorthefeed istooslowortoofastaccidentsarelikelytooccurThe area directly in front of and behind the workpiece is

known as the lsquofiring zonersquo or the lsquored zonersquo This is where apiece of work is likely to go as it leaves the lathe Make it ahabit to keep clear of this zone when you turn the lathe onLearnwhere theNoVolts switch is as youmightneed to turnthelatheoffquicklyByfollowingalltheaboveadviceyoushouldnowbeableto

worksafelyfullyawareofanysafetyproblemsthatmightariseAtthispointyounowknowhowtoinstallthelathelookafter

itclean itandmaintain it InChapter3wewill lookatcuttingtoolsandexaminehowtoselectcuttingspeedsandfeeds

Thisbarisstickingouttoofarfromthebackofthelathe

3CuttingToolPrinciplesFeedsandSpeeds

The first part of this chapter will look at the materials fromwhichcuttingtoolsaremadeaswellastheirbasicshapeandgeometryWewill thenconsider selectingsuitablespeedsandfeeds

MAINTYPESOFTURNINGTOOLS

There are three main types of turning tool used in modernworkshops HSS (high speed steel) tools carbide brazed-ontoolsandinsertedtiptoolsAllhavetheirusesintheworkshopandformost jobsthere isnopreferenceforonetypeovertheothersTherearealsocarbonsteeltoolbitsalthoughinpracticetheyarejustaboutobsoleteCarbonsteeltoolscanbemadeinthe homeworkshop but apart frombeing used tomake formtools(seeChapter11)thereaderisunlikelytousethismaterialfortools

Ageneral-purposeHSSturningtoolsuitableformildsteel

HSSTOOLS

HSStoolscanbepurchasedsinglyorinsetsalreadygroundtothecorrectshapeIt ischeaperhowevertopurchasethemassquare tool blanks in various sizes ready for you to grind toshapeThecompleteready-groundsetswillprobablycomewithseveralshapesincludedthatyouwillneveruseIfyoucanbuyafewready-groundtoolscheaplytheywillbeofuseasguidestoseehowtosharpenyourownHSStoolblanksHSS form tools from industry are often available second-

handTheseareespeciallygroundtomachineacomplex formall in one go You can often find some that are ground to asuitable shape to form the end of a threaded componentincludingtheundercut

HSSformturningtools

Brazed-onCarbideTools

Brazed-on carbide-tipped tools are quite useful especially forfacing and boring cast iron but they really need a diamond-facedgrindingwheeltokeepthemsharpCarbidetipsandtoolscomeinvarioussizesandhardnesstosuitindividualmaterialscarbidetoolsforsteelwilloftenbepaintedbluethoseforcastiron are painted red and those for stainless steel are paintedyellowThecolourindicatesthesuitabilityofthetoolforcertainmaterials

Brazed-oncarbide-tippedtoolscomeinvariousgradesshapesandsizes

InsertedTipTools

InsertedcarbidetiptoolsareveryusefulbuttheyarenotcheapThe tipsarenotusually sharpenedafterwearingout you justthrow the tip away and fit a new one Most modern carbide

inserts however do have more than one cutting facesometimestheyhavetwoandoccasionallyfourormorecuttingedgesareavailableYoucanevengetformturningtoolswheretheinsertisroundandcanberotatedafull360degrees

Theleft-handtoolisblueindicatingitisformildsteelwhiletheright-handtoolisredindicatingitisforturningcastiron

Some diamond-shaped tips can be used in different toolholders two edges are used in one tool holder and the othertwoedgesareusedinanothertoolholdersoyougettwicethelifepertipInserted tip tools are available for internal and external

screwcuttingwherethetipsareheldat thecorrecthelixangleofthethreadinthetoolholderThedrawbackisthecostofthetipsandeachsizeofthreadusuallyneedsitsownsizeoftip

Aninsertedtipcarbideturningtool

Carbidegroovingtools

InsertedtipgroovingtoolsareidealformachininggroovesforOrings and circlips Theyare available inmany standardwidthsandcanoftenbeusedasparting-offtoolsforsmallerdiametersOneof themostusefulgrooving tools forsmallersizegroovesandpartingoffistheMiniThinsystemassoldbyMSCIndustrialSupplyCo

TheMiniThintoolholderisidealforgroovingandalsoforpartingoffsmalldiametersTheshankissostrongcomparedwiththecutbeingtakenthatusinganoverhangasshownisquite

safe

Coatingstoreducetoolwear

Tipsarealsoavailablewith various coatings that improve toollifeThemostcommoncoatingistitaniumnitride(TiN)whichisgold in colour Other coatings that offer slightly better wearresistancearetitaniumcarbonnitride(TiCN)whichisbluegreyincolourandtitaniumaluminiumnitride(TiAlN)whichisvioletbronzeReady-groundHSScuttingtoolssuchasdrillstapsandreamers are also available with these coatings but once yousharpenthecutterthecoatingisgoneTipped toolsneedadeeper cut ahigher feedandahigher

speed than HSS tools Thismeans that the lathe needs to bestrongrigidandhaveamplepowertodrivethe lathemandrelwhen taking a heavy cut this rules out using tipped tools onlathessmallerthanabout2in(50mm)centreheightSmaller tools are made to fit the Unimat and similar small

lathesbutthesemachinesjustdonrsquothavethepowerneededtodrivethemAtbesttakingacutwillstopthelatheatworstthetoolwillchip

Insertedtiptypes

Inserted tip tools come in many shapes and sizes Some tipshapes and sizes are made to an international standard andothers are to the makerrsquos own standards Wherever possibleuse ISOstandardtoolsas thetipswillbe interchangeablewiththosefromothermanufacturersandwillprobablybecheaperaswell The ANSI system commonly used in the USA is notcompatiblewiththeISOsystemusedintherestoftheworldIfyour lathe ispowerfulenoughyoucantakeadvantageof

insertedtippartingoffbladesThesearemounted inaspecialtoolblockandthebladecanbeslidinoroutdependingonthediameteryouarepartingoffThebladecarriesan inserted tipspecially designed for parting off There are three types of tipavailablesquare-endedtipstipsthatareangledtotheleftand

tips that are angled to the right Square tips are used forgeneral parting off tips angled to the left are usedwhen youdonrsquotwanttoleaveapiponthebackendoftheworkandtipsangledtotherightareusedwhenyouwantacleanfaceonthefrontoftheworkThe parting off blade is oftenmounted upside down at the

backofthe lathecrossslideTheactionofpartingofftendstolift the whole cross slide slightly and forces the cross slidetightly into thematching dovetail whichmakes itmuchmorerigidIfthepartingofftooldigsinwhileinthebacktoolpostthetool tends to lift and push away from the work whereas in afronttoolpostthetooltendstodiginandpullintothework

Simplifieddiagramofpartingofftoolangles(A)straightpartingtool(B)angledtotheleft(C)angledtotheright

POWERREQUIREMENTS

Whenturningmildsteelorstainlesssteelwithanycarbidetoolthe machine horse power required is considerably more thanthat required forordinaryHSStoolsThe twomain reasons forthisarethatcarbidetoolsoftenhaveanegativerakeangleonthecuttingedgeasthistypeofedgelastsmuchlongerthanapositiveangle especially for intermittent cuts andbecause in

industrial use carbide tips are called on to remove largerquantitiesofmetalathigherspeedsandfeedsFor guidance on using tipped tools in the small workshop

wheretimeisnotasimportantasinanindustrialenvironmentIwould recommendusing twice the speedused fornormalHSStools and a fine feed of about 0002in (005mm) per rev as astarting point This can be adjusted up or downdepending ontheresultsThemaindifferencebetweenHSStoolsandcarbidetippedtools(eitherbrazed-onorinsertedtip)isthehorsepowerrequirementofthemachineinuse

Thispartingofftoolismountedatthebackofthelatheinaspecialbacktoolholder

SELECTINGTHECORRECTSPEEDSFORDIFFERENTMATERIALS

Overmanyyears through trialanderror cuttingspeedshavebeendeterminedthatgiveanoptimumtoollifebalancedwithadecent surface finish These speeds are normally quoted inlsquosurfacespeedinfeetperminutersquoSpeeds and feeds used on industrial machines where the

primary tools will have inserted tips will be a lot higher than

thoseusedinthesmallworkshopwhereHSStoolsarethenormThe accompanying table gives an idea of the speeds that

shouldbeused forvariouscommon typesofmaterial likely tobefoundintheworkshopThespeedslistedshouldbesuitableforbothturninganddrillinginthelatheForreaminguseabout25percentoftherecommendedspeedsThe table is a guide only and it is likely that the machine

speedsavailablewillnotbeexactlythoserequiredandyoumayhavetoresorttolsquonearenoughisgoodenoughrsquoSetthelathetothe nearest speed lower than indicated in the table for thediameterandmaterialbeingcutThiswillbefineforHSStoolsDouble the recommended HSS speed for carbide tools For

parting off use about 30 per cent of the recommended HSSspeed For form tools use about 50 per cent of therecommended speed for the initial cuts and then engage thecorresponding back gear (just switch to back gear leaving thebelts on the same pulley) and gently tap the handle until itreachesthefinishedsizeandallowittofinishthecutbyitselfYou may have to adjust the speed down if you get a lot ofchatter

Forturningcastironuseacarbide-tippedtoolrunningattheHSSspeedtoremovetheskinYoucanthenfinishtheturningwithaHSSsteeltoolifyouwishPlease remember if doing any work that might be

unbalancedstartoffslowlyandincreasethespeedabeltstepatatime

THEACTIONOFCUTTINGTOOLS

Basicallya lathe tool isawedge that is forced into theendofthe rotating bar to remove metal As long as the tool is fedforwardwhilethelatheisrotatingmaterialwillberemovedA typical right-hand turning tool has a cutting angle of 90

degreeslessthesideclearancelessthesiderakeThecuttingangle for this example is 90ndash10ndash10= 70 degrees This is theangle that is wedged into the work to remove the materialSoftermaterialswillhaveasmallercuttinganglewhilehardermaterials will have a larger cutting angle Tool angles varydependingonthetypeofmetalbeingturnedToolsforturningsofter metals usually have higher rake angles than thosedesigned for harder metals since a turning tool will normallyholditsedgeforlongerinsoftermaterialsBrassalthoughsoftusuallyhasnotoprakeonthetoolatallOther angles to be aware of are the top rake and the side

rake

CUTTINGTOOLSHAPES

The followingaresomeof thedifferent shapes thatyoumightfindusefulforgeneralturningandmetalremoval

Right-handknifeturningtoolAllrakeanglesare10degrees

Right-hand knife tool This is used for general turning andfacingofbarstockDependingontheworkyouaredoingyoumayfindaleft-handversionofthistooluseful

Typicalroughingtool

Right-handroughingtoolIthasaleadingangleandasmallradius on the tip of the tool This tool is used for fast metalremovalwherefinishisnottooimportantAgainyoumayfindaleft-handversionusefulAroughingtoolcuttingatanangletoabarwillremoveachip

widerandthinnerthanatoolcuttingat90degreestothebarThis improves tool life although you will have to square theturningupwithastandardknifetool

Typicaldouble-sidedroughingtool

Double-sided roughing tool It can turn towards the left orright It canalsobeusedasaplunge tool to removematerialfroma groove orwhere the component needs to be lsquowaistedrsquodown

Simplepartingofftool

Simple parting off tool This is suitable formostmaterialsYouwillprobablyneedalargeoneforpartingofflargediameterbarsaswellasasmalloneforpartingoffsmallcomponents

Internal(top)andexternal(bottom)screwcuttingtools

ScrewcuttingtoolThisisusedforcuttingscrewthreadsTheanglewilldependonthethreadyouarecutting60degreesformetric55degreesforWhitworthandBSFetc

Shallowboringtoolcapableoffacingacrossthebottomofahole

Boring and facing tool This toolrsquos unusual shape will befound very useful when recessing a large bore It will plungestraight intoasmalldrilledholeandwillalso face rightacrossthebottomoftherecess

Double-endedchamfertoolchamferingadiameter

Double-ended chamfering tool It has 45 degree angles atbothendssoitcanbeusedtochamferexternaldiametersandinternalbores

Double-endedchamfertoolchamferingabore

Othershapescanbeusefulbutthetoolsshownhereshouldbesufficienttogetyougoing

BORINGTOOLS

Boring tools are used to clean up a previously drilled holepossiblytomakeitruntruebutmorelikelytoensuretheholeistothecorrectsizeTheyarenormallylongerthanordinarytoolsandtendtostickoutfurtherfromthetoolholderHSStoolsaresuitableformostusesCarbideinsertedtipboringbarsarealsoreadilyavailableandarethebestbetforturningcastironinthesmallworkshop

HSSboringbar

For really small holes down to2or3mm indiameter solidHSSandcarbideboringbarsarereadilyavailableAlthoughtheyarenotcheaptheywillbefoundveryusefulandquicktouseAnothermethodofboringahole is tousea longseriesslot

drillasaboringtoolInuseclamptheshankinthetoolholderwiththepointatcentreheightmakingsuretherestoftheslotdrillisclearofthesideoftheboreYoucanthenrunitthroughtheboreinasimilarmannertoastandardboringbar

Asmallcarbideboringbarinsertedintoamildsteelshank

PARTINGOFFTOOLS

PartingofftoolsprovideaquickwayofcuttingoffworkfromtheparentbarThereisrarelyanyneedtoworryaboutcuttingthecomponentofftothecorrectlengthtogetagoodfinishAslongasthecomponentislongerthanrequireditcanbeputbackintothe chuck or a collet and the parted off face can be faced tolengthorotherwiseworkedonThepartingofftoolcuttingfacecaneitherbesquareoritcan

beangledtotheleftorright(seepage43)Thesideofthepartingofftoolcouldevenberadiusedsothat

it forms a radius on the end of the next component orchamferedtoformalead-inedgeforthenexttool

CUTTINGLUBRICANTS

Tomake cutting tools cut easily and to prolong their life it issometimesbesttouseacuttinglubricantForsteelIpreferneatcuttingoilItlubricatesbutisnotidealforcoolingtheworkIn industry coolant is normally used This is oil that has an

additivetomakeitsolubleinwaterMostsolubleoilswilldobutthe synthetic ones tend to sting your hands if you have anyopen cuts I would not recommend using soluble oils on thehome workshop lathe as I think they tend to wash thelubricating oil off the slideways and can encourage rustHowever this ismypersonalpreferenceandmanypeopleusesolubleoilinthehomeworkshopwithoutanyproblemsOil is suitable for use when cutting steels mild steels

stainlesssteelsandhighcarbonsteelssuchassilversteelThebestlubricantwhencuttingaluminiumisparaffinItstops

thealuminiumfrombuildinguponthecuttingtoolBrassandcast ironarenormallycutdryWhenturningcast

ironona lathe if the latheisfittedwithasolubleoiltankthecastirondustwillhaveanaffinityforthesolubleoilIfthelatheisthenusedonaluminiumthefreecarboninthecast ironcancontaminatethealuminiumwithblackstreaks

Inormallyplacetheoilorparaffininasmalldish(actuallyacatordogfoodbowl)andapply itbyhandwithasmallbrushThisdoesallIneedThenextchapterlooksatgrindinglathetools

4SharpeningToolsandHoldingThemintheLathe

ThenexttaskistogrindasetofusefullathetoolsThe first thing you will need is an off-hand grinder The

grindercanbeadangerousmachineso itshouldbeusedwithcare Eye protection must be worn the guards should becorrectlyfittedandtheremustbeadequateilluminationIdonrsquotlike using a grinder in a small workshop as the grinding dustflies everywhere and canget onto themachine slideways andtools generally making the workshop dusty and dirty Ifpossible set up thegrinder in a separate areaaway from theworkshopIhavemygrindermountedonafoodchoppingboardso I can carry it outside to use This has the addedbenefit ofdaylight although you are dependent on the weather or youmightneedtouseitafterdark

Theguardofthisoff-handgrinderhasbeenwidenedtoacceptarecessedwheel

GRINDINGWHEELS

IthasalwaysbeenstatedthatyoushouldnevergrindatoolonthesideofthegrindingwheelSofollowingthistheorywewillbeusingarecessedwheelwhereitswidthismuchthickerthanthepartofthewheelusedtoclampthewheeltothegrinderIstruggledtofindarecessedwheelof6in(150mm)diameterandfinally found a 60 grit grinding wheel on a personal visit toAxminster Power Tools in Devon (I could find only an 80 gritwheel in theircatalogue)Thewheels I like touse forgrindingare A60K5V if I can get them and I prefer the white wheelsdesigned for the harder tool steels rather than the grey orbrown wheels which are more suitable for softer mild steelsThedesignationbreaksdown like thisA stands foraluminiumoxide 60 is the grit size K is the hardness (I J and K beingmediumhard)5 is thestructure(thespacebetweengrainsofgrit) and V is for vitrified the method of bonding the grainstogetherTheKandthe5canvaryabiteitherwayandthegrit

shouldbe4660or80with60beingpreferredThe80gritisabitfineandwillclogupquitequicklySo-called green grit wheels made from silicon carbide are

available for sharpening carbide tools They are usually softerthanaluminiumoxidewheelsinordertoallowthegrittobreakdownbeforethewheelbecomesglazedfromgrindingthemuchhardercarbide

Witharecessedwheelyoucancutontheouterfaceoftherecessedsideofthewheel

TestingtheWheel

The first thingyoushoulddowhenbuyingawheel is tomakesurethat it is ratedatasufficientlyhighspeedfor thegrinderon which it is to be used Off-hand grinders usually run ataround2900rpmsoyouwillneedawheelratedtoatleastthatspeed it is all the better if the grinding wheel is rated at ahigher speed than the grinder Care should be taken whenhandlinggrindingwheelsastheyarequitefragileifknockedordropped A grinding wheel should only be purchased from areputableengineeringsupplierSupportyourgrindingwheelona piece of wood and tap the wheel gently with a plasticscrewdriver handle or similar The wheel should lsquoringrsquo if itsoundsdullitshouldbebrokeninhalfandeitherthrownawayorusedontheworkbenchasasharpeningstoneNeverthrowawheelawaywithoutbreaking it into twoyouneverknowwho

mightgettheirhandsonit

Thistoolrestwasdesignedtosharpenplaneironsandchiselsbutitisfineforlathetools

Amoderndigitalanglegaugeisidealforsettingthetoolrest

MountingtheWheel

The wheelrsquos bore should be the same as the spindle of thegrindingwheelOften theborewillbe largerandyouwill then

need some plastic spacers to reduce it Spacers should bereadilyavailable fromyour localengineeringsupplierYoucanturn thespacers fromplastic if youcanrsquotbuyany ready-madeonesAt each side of the wheel you should fit a paper washer

thesearemadeofblottingpapertypematerialandwillprobablyhave been supplied already stuck on the wheel The grindershould have twometal flanges one to fit at each side of thewheel Both flanges should be the same diameter These willhold the wheel true and spread the tightening load on thewheelThegrinderwillhavetwodifferent threadsontheendsof its spindle The right-hand side of the grinder will have aright-hand thread and the left-hand side will have a left-handthreadThedifferentthreadsaretostoptheclampingnutsfromunscrewingwhenthegrinderisrunningTofitthewheelremovetheguardandundothenutRemove

the metal flange and then the wheel Make sure the flangesdonrsquothaveany remainsof theoldpaperwasheron themPutthenewwheelontothegrinderspindle(rememberthespacerthepaperwashersandtheflangesateitherside)andscrewthenuthand-tightFinallyholdthewheelgentlyandgivethenutapinchupwithaspannerYoudonrsquotneedtoover-tightenthenutjustsufficiently tostop thewheel fromcoming looseRefit theguard and spin thewheel by hand to ensure it is not rubbinganywhereNowwearealmost ready to switch thegrinder onBeforedoingsohoweverputonyoureyeprotectionandstandtoonesideofthegrindersoyouarenotinlinewiththewheelshould it burst Then switch the grinder on All should be fineandthewheelshouldberotatingsafely

TOOLREST

Theworkrestsuppliedwithanoff-handgrinderisusuallyjustabitofbentsheetmetalboltedonItisusablebutonlyjustI recently purchased a ready-made tool rest as a basis for

makinganimprovedgrindingrestThiswasoriginallydesigned

forsharpeningplanebladesandchiselsforwoodworkingbutitmakes an ideal rest for sharpening lathe tools It is made ofaluminiumandisfullyadjustableforangleThebestmethodofsetting the rest to the correct angle is to use a digital anglegauge These are now very cheap and are readily obtainableThepositionoftherestinrelationtothegrindingwheelcanbeadjusted on its sliding base Many designs for tool rests havebeenpublishedandyoucouldmakeoneofthoseinsteadifyouwishtosavemoneyThetoolclampassupplied isdesignedtoclampplane irons

andchiselssothisneedstobechangedLathetoolsneedtobepresented to the grinding wheel at the correct angles If youdonrsquot have a digital angle gauge this can be achieved usingsimpleguidesmadefromanglesheetmetalandsomescrewsIused gauge plate made from a high carbon steel with anaccurategroundfinishthatcanbehardenedandtemperedbutmild steel would be perfectly suitable if you donrsquot have anygaugeplateavailableYouwillfindaprotractorusefulyoucangetasteelonewith

an adjustable blade for a reasonable price The protractorwillbeusedtosetthetoolanglethatisgroundonthetools

Sheetmetalprotractorsareavailableverycheaply

LATHETOOLGEOMETRY

LathetoolsneedtobegroundtocertainanglesbuttheanglesdonrsquothavetobeexactFormosttoolssomewherehandywilldounless you are grinding a form tool to a particularly accurateshapeIthasbeennormalforbookstoshowtheanglesontoolsas used in a production environment where tools will ideallyhavealonglifeoftenthislifeiscalculatedaslastinganeight-hourshiftsothetoolonlyhastobesharpenedandresetonceadayInthehomeworkshopwecan increasethesecuttingangles

andgetbettercuttingattheslightexpenseofshortertoollifeWehavealreadyexplainedtheshapesof the tools thatyou

willfindmostusefulToolanglesareknownbytechnicaltermstop rake front rakeside rakeandback rakeThe rakeanglesvary depending on thematerial to bemachined but a set ofstandardtoolswillgetyoustartedSomeoftheaccompanyingphotographsareactuallyoflarge-scalewoodenmodels

Theleft-handtoolissuitableforbothfacingandturningtheright-handtoolissuitableforturningonly

Left-handsideofthefacingandturningtoolshowingthefrontandtoprake

Topofthefacingandturningtoolshowingthefrontandsiderelief

Left-handsideoftheturningtoolshowingthefrontclearanceandthetoprake

Topoftheturningtoolshowingthefrontandsideclearanceandthetoprake

GRINDINGATOOL

WhengrindingHSStoolstrytokeepthemascoolaspossibleIfan HSS tool becomes too hot and is then quenched in waterminutecrackswillformonthecuttingedgesThesecrackswillmakethetoolcuttingedgebreakdownveryquicklywhenusedThe best practice is to grind a little bit off the tool and thenquenchitwhileslightlywarmDonotletthetoolgethotdipitin thewater little andoften This should ensure the tool edgedoesnotbreakdowninuse

GrindingYourFirstTool

Most angles can be ground by using the tilting table whileothersmayneedtobefixedinrelationtotheperipheryofthegrindingwheelThefrontandsideofthetoolcanbegroundbytippingthetableatthecorrectanglewhereasthetoprakecanbegroundontheperipheryofthewheelThegrinder should first be switchedoff andunplugged Set

thetoolresttotherequiredangleusingthedigitalanglegaugeoranangletemplateandtightenuptherestBefore switching on the grinder ensure that everything is

freetorotatebyspinningthegrindingwheelbyhandIf all is well put on your safety glasses and switch on the

grinderPlacethetoolonthetoolrestupagainstthesideoftheprotractor Slide the tool along the table until it reaches thegrindingwheel andmetal starts to be removed Slide the toolbackwards and forwards slowly along the restwhile putting alittle light pressure on the tool so that it continues to pressagainst the grinding wheel When you have removed a smallamountofmaterialcoolthetoolbitdownAtnotimeallowthetool bit to get hot Continue grinding until you have removedsufficientmaterialfromthetoolbit

Thegrindingrestissettothecorrectangleof10degreestogrindtheendofthetool

Grindingthefirstangle

TurnthetooltotheotherangleanddothesamesothatnowboththefrontandsideclearanceangleshavebeengroundThis toolwill be enough for brass but for steelwe need to

grindthetoprakeWhengrindingthetoprakeonaright-handtool the slide rest needs to be higher than the centre of thegrinding wheel so that it grinds the tool at approximately 10degrees

Thefirstanglehasbeenground

You have now ground your first lathe tool The tool asreceivedfromthegrinderwillbetooroughtousehoweversoyouwillneedtohonethecuttingedgesYoucandothisonanoilstone(usedwithfineoillike3in1)orwithadiamondlaporusing a combination of the two Lightly lap the front and sideclearanceanglesuntilyougetagoodfinishand lightlyhoneaverysmallradiusonthetipofthetoolFinallyhonethetoprakeangleandyourtoolisreadyforuse

Grindingthesecondangle

Thesecondanglehasbeenground

AllofyourHSSturningtoolscanbedoneinthiswayOnlytheangleswillvaryandthesecanbesetusingadigitalanglegaugeandprotractorAnoccasionalhonewillresharpenyourtoolsaslongasyoutreatthemwithcareA similar range of HSS tools and a parting off tool all with

zero top rake shouldbeavailable if youwill be turningbrassUnless you are doing quantity production one tool holdershouldbesufficientforbrassAsatoolforbrasshasnotoprakeandyouwouldnotnormallygrindthetopawayaslongasyoubuy tool steel of the same size the tip height will remain thesameYoucanthenusethedifferenttoolsinoneholderwithouthavingtoresettheheight

MACHININGCASTIRON

Carbide-tippedtoolsareidealformachiningcastironAsimplebrazedupcrankedtoolwithasmallchamferonthenosewilldoforbothturningandfacingcastironcomponentsThemainuseof this tool will however probably be truing up the faceplatethat comes with the lathe The large diameter combined withtheintermittentcutovertheboltgrooveswoulddestroyanHSStoolinafewsecondsAsmalltippedboringbarwillbeidealfor

taskslikeboringcastironcylinders

Grindingthethirdangle

Asimplediamondlap

Thethirdanglehasbeenground

Tosharpentippedtoolsyouneedadiamondwheelorifyouwant to remove large amounts of carbide a silicon carbidewheeloftencalledagreengritwheelowingtoitsusualcolourSilicon carbide wheels are much softer than aluminium oxidewheels as they need to break down faster to present newsharpergrainstothecarbidetoolAdiamondwheelisonlydesignedtolightlylapatippedtool

itisnotsuitableforremovinglargeamountsofcarbide

Diamondcupwheel

TOOLHOLDING

Smallerlathessuchasarefoundinmostworkshopsmayhaveatopslidewithatoolclampforindividualtoolsablockwithasingle slot to take the tool a four-way turret (or sometimes athree-way)oraquick-changetoolblockandholdersetThereisalsotheso-calledAmericantoolpostwhichisaroundbarwitha slot through it and a bolt in the top to clamp the tool ItusuallycomeswithmatchingdishedwasherstoadjustthetoolheightThistypeisnolongerverycommononlathes

Quick-changeToolPost

Themostversatiletoolholdingsystemisthequick-changetoolblockwithmatchingholdersThedrawbackwiththissystemisthe cost of extra tool holders you need quite a few one foreachtoolThequick-changetoolblockmountsonthefrontofthelathe

normallyontopofthetopslide(Blockscanbefitteddirectlyon

thecrossslidebytheuseofaraisingblocktoaidrigidity)

Quick-changetoolblock

Each holder is set up with its own particular tool The toolholderscanbe individuallysetso that the turning tool isdeadoncentreheightandispresentedcorrectlytotheworkpiece

Quick-changetoolholder

Quick-change tool holders are available with a straight cutslottotakestandardsquareshanktoolholderswithastraightcutwiththeadditionofaVeecut-outinthebottomforusewithroundtoolssuchasboringbarsandasafrontpartingoff tool

holdertotakeahighspeedsteelpartingoffbladeRearpartingoff tool holders are available to take an inverted parting offbladeeitherahighspeedsteelbladeoran insertedtipbladeLeft-handed and right-handed extended tool holders are alsoavailableandmayoccasionallybequiteusefulThetoolblock isnormallymountedonthetopslidebutyou

cangetraisingblockstouseinsteadofthetopslideThismakesthetoolholderblockmuchmorerigidAbackquick-changetoolblockwillneedmountingonaraisingblock

Backofaquick-changetoolholdershowingthedovetailtypeofmounting

Right-handandleft-handextendedtoolholders

StandardtoolholderwithaVeetotakeroundtoolholders

Frontpartingofftoolholder

ToolClamp

Satisfactoryworkcanbedonewithatoolclampedontothetopslideusingshimsteel toset thecentreheightof the toolThemaindrawbacksarethatyoulosethepositionofthetoolwhenyoutakeitoffthetopslidetofitthenexttoolandyoualsolosetheaccuratecentreheightofthetoolunlessyoukeepthetoolandshimstogetherIfyouaremakingonlyonecomponentthisisnotaproblembutitisanuisanceifyouaremakingabatchofmatchingcomponents

Simpletoolclamp

Single-slotBlockToolPost

AblocktoolpostisoftensuppliedwiththecheaperlathesThetoolpostisliterallyablockofmetalwithaslotcutinittotakethe turning tool It is relatively easy to set the tool up at thecorrectcentreheightbyusingvariousthicknessesofshimThisisfineforthebeginnertoturningwhoisjuststartingoutbutitisbesttoreplaceitwithafour-waytoolpostoraquick-changetool post You could of coursemake several block tool postsandkeepeachonesetwithadifferenttool

Four-waytoolpost

Backtoolpost

Four-wayToolPost

Four-wayToolPost

Thefour-waytoolpost isagoodcompromiseona latheasyoucansetfourtoolsintheturretandrotateeachoneintopositionas needed This speeds up production and is a lot faster thanusingasimpletoolclampThedrawback isthatthetoolsstickoutof the turret fourdifferentwaysandyoumightcatchyourhandonasharp toolAsimple ratchetstopensures thateachtool repeats its position when the tool post is rotated so theworkisaccuratelyturnedeachtimethetoolisusedAduplicatefour-waytoolpostwithtoolsforbrasswillspeedupproductionevenmoreCastingsareavailabletomakeyourownthree-waytoolpost The three-way toolposthas theadvantageofbeingable to get close to the work when you are turning betweencentresFor the front tool post I would recommend right-hand and

left-hand roughing tools right-hand and left-hand finishingtools a tool groundup to face barswhile using a half centreand a Mini Thin inserted tip grooving tool with grooving andparting off inserts You will also need large and small boringbarsbothHSSandwithinsertedtipsTheHSStoolsshouldbegroundupforuseasgeneral-purposeturningtoolsformildsteelandsimilarmaterialsThecarbideinsertedtipboringbarshouldbefineforcastiron

BackToolPost

You can fit a quick-change tool block to theback of the crossslideaswellasthefrontSpecialholdersareavailabletotakeaHSSparting off blade or an inserted tip parting off blade Thebladewill be angleddown to give top clearancewhenpartingoffTheseback-mountedtoolblocksareveryhandyastheycanalsobefittedintotoolholderswithafacingtoolorachamferingtoolFor a back tool holder set-up I would recommend an HSS

partingoffbladeafacingtoolforcastironandadouble-ended45-degree chamfering tool that can be mounted parallel with

the chuck or at 90 degrees to it This set-upwill allow you tofaceaworkpiecechamfertheoutsidediameterandortheboreandpartitofftolengthThenextchapterlooksatholdingworkinachuck

5WorkholdingintheChuck

This chapter covers the different types of chucks how to usethemandsetupworkinthemaccurately

Aself-centringthree-jawchuckfittedwithlsquodrilljawsrsquoNotetheexternaljawswhichareinterchangeablewiththedrilljaws

USINGCHUCKS

Themostusefultoolsforworkholdinginthelathearethree-andfour-jaw chucks The three-jaw chuck is usually of the self-centringvarietythistypeofchuckcomesasstandardwithtwosets of jaws The first set of jaws are known as inside or drilljaws as they are most useful for holding round and hexagonbarsTheother setof jawsareoutside jawswhichholdworkusuallyindiscformontheoutsideSelf-centringmeansthatwhenyouinsertabitofbarintothe

chuck and turn the chuck key the chuck centralizes theworkpieceas it tightensup It isunlikely to runperfectly truebutitshouldruntruewithin3or4thouYou can also purchase soft jawswhich are exactly as their

namesuggestsYoucan thenbore themout to fit thework Ifyouborethemonthelatheyouaregoingtousethemontheworkwillrundeadtrue

Asetofsoftjawscanbeturnedorboredtosuittheworktobeheld

Aself-centringfour-jawchuckThesealsocomewithexternaljawsandsoftjawsareusuallyavailable

Self-centring four-jaw chucks can be used for square barsTheyarealsousefulforholdingroundbarswithmoregripthanathree-jawself-centringchuckSoft jawsarealsoavailableforfour-jawself-centringchucks

Afour-jawindependentchuck

Youare howevermuchmore likely to comeacross a four-jaw independent chuck than a four-jaw self-centring chuckIndependent means that the jaws can be moved individuallyand the jaws can also be reversed one two three or four ofthemdependingontheworktobedone

Abaseplatecastinginafour-jawindependentchuck

Wewillfirstlookatthethree-jawchuckThebestmethodofmaking a component in one of these is if possible to turn itcompletely at one set-up If you put a piece of bar into thechuck face the end centre drill drill and ream it skim thediameterandpartitoffitshouldbeconcentricalloverThisisbecausewehaveturneditallatthesamesettingwithouttakingit out of the chuck If we need to machine the other endhoweverwhenwe turn it roundandput it back in the chuckthechancesareitwillnotruntrueThis iswherethe four-jaw independentchuckcomes inYou

canput thecomponent intoa four-jawchuckandset it to runtrueusingthedialtestindicatorAnyworkyoudoonthepartedoff end should then be concentric with the rest of thecomponentWhensettingworkinafour-jawindependentchuckfor a second operation use some thin shimbetween the jawsandtheworkpiecetoavoidmarkingtheworkWorkisoftenheldinafour-jawchuckbecauseitisacasting

anoddshapeorsquareandsowonrsquotfitintoathree-jawchuckIf thework just requires tobe faced flat rightacross the facethereisnoneedtosettheworkrunningradiallytrueItshouldbe near enough on the centre line as long as the work is

reasonablybalancedYou could of course put the component into a three-jaw

chuckbyfittingsoft jawsandmachiningorboringthemouttotake the component This is the best option ifmaking severalcomponentsthatneedtobeidenticalbutifyouonlyneedoneor two components a four-jaw independent chuck will be thequickestmethodofmachiningthemLargerdiameterscanbeheld ina three-jawchuckbyusing

theoutsidejawsThesehavealargeradiusontheinsideofthejaw ifthisradiusis largerthantheworkpiecethejawsshouldnot tend to dig into the work and mark it Outside jaws areuseful forholding components like small flywheels locomotivewheels and chuck backplates when machining the bores ofholesorwhenmachiningacrossthefaceWhenmachining thindiscs it isuseful toputsomepacking

behindthedisctomakeitstandproudofthejawsTostopthepackingflyingoutwhenthemachineisrunningmakeasetofthree or four packing pieceswith grooves at each end and fittensionspringstothemTheyshouldallbethesamediametersothatthebackoftheworkisparalleltothechuckThelengthand grooves can vary slightly as they donrsquot affect theparallelismTheyarequickandsimpletomakesoacoupleofsets of different diameters should find their way intoeverybodyrsquostoolbox

AlthoughmostlathechuckkeyshavesquareendstheyareoftenofdifferentsizesKeepeachkeywithitsownchuck

ChuckKeys

I have alreadymentioned that the chuck key should never beleftinthechuckwhenitisunattended(seeChapter2)PutthekeyintothechuckuseitandputitsafelyawayassoonasyouhavefinishedwithitIfyouswitchonthelathewiththekeystillinthechuckyoumightneedatriptothehospitalDonotuseexcessive forcewhenyou tightenup the chuck

Do not use a piece of tube a spanner or anything else as alever thechuckkeyon itsownshouldbesufficient to tightenthechuckontotheworkWhenusinga four-jawchuckasmallchuckkey littlemore

thanaknurledknobwithasquareoncanbeusedtoadjustthejawsinandoutpriortotighteningupwiththeproperchuckkeyThiswill save timeover adjusting the jawswith a large chuckkeyTo turn the independent four-jaw chuck jaws round a

carpenterrsquosbracewithapieceofsquarebarinittofitthechuckwillmakeshortworkofreversingthe jawsbutdonrsquotuse it forthefinaltighteningasitisliabletostrainthejaws

STARTINGTOTURN

Before going any further you need to learn how to do basicturningFor thisyouneed toput the three-jawchuckonto themandrelStartbycleaningthemandrelwithacleanbitofragorsimilar(Ikeeparollofpaperkitchentowellingintheworkshop)Nowyouneed toclean thechuckrsquosboreand threadusing thetwotoothbrushmethod(seeChapter2)BoththemandrelandthechuckshouldbecleanbeforeyouattempttofitthechucktothelatheSelecting and grinding turning tools has already been

discussed (see Chapter 4) so by now you should have acorrectlygroundturningtoolsuitableforroughingoutapieceofsteelbar

Barwithapiptoolaboveorbelowcentreheight

MakingaToolCentreHeightSettingGauge

Thistoolneeds itscuttingedgesettothecentreheightofthelatheThereareseveralwaystodothisbutoneoftheeasiestiswith a home-made height gaugeWhen starting out this is achickenandeggsituationyouneedtomakethegaugetosettheheightbutyoualsoneedatoolsetatthecorrectheighttomakethegaugeThesimplestwaytoovercomethisproblemistosetthelathe

tooltotheapproximatecentreheightandtakeacutacrossthefaceofthebarDependingonwhetherthereisapipremainingon theendof thebaryoushouldgetan ideahow farout thetoolheightisIfthereisnopipthismeansthetoolisoncorrectcentre height or too high A pipmeans the tool is too lowOfcourse you may have been lucky so try dropping the toolslightly until a pip remains You can then raise the tool a fewthouatatimeuntilthepipdisappearsThetoolshouldthenbeoncentreheight

Barwithnopiptooloncentre

Nowthatthetoolisatcentreheightyoucanmakeasimpleheight gauge Turn a piece of bar down to as close to frac12in(12mm)asyoucangetandleaveitinthelathechuckMeasurefromthetopofthecrossslidetothetopofthebarwithacheapheightgaugeLowertheheightgaugebyhalfthebardiameterTheheight

gaugeshouldbeexactlyonthelathecentrelineMakeanoteofthisdimensionWe now need to look at how to turn a bit of bar to an

accuratediameterWhenturningabartosayfrac12in(12mm)youneedtostartwithsomethingslightlylargerInthiscasethiswillbe⅝in(16mm)diametermaterialasthisisastandardsizeCutapieceofmaterialabout2in(50mm)longandputitinto

thechuckwithabout1in(25mm)stickingoutSkimtheoutsidedown to about 0510 thou or 1225mm which is 10 thou(025mm) above the size required (You should be aware thatmosthobbylathedialsremovetwicewhattheysayaonethoudivisionforexamplewillusuallytake2thoufromthediameterLargercommercial lathesaremuchmore likelytotakeoffonethoupergraduation)Nowtakesmallcutsuntilalmosttosizeusingpowerfeedif

you have it andmaking sure you knock the feed off before ithitsthechuckStopthelatheandwindthecarriagetothestart

of the bar Take another cut at the same setting andmake anoteofthediameterTakeanothershallowcutbutthistimegoonly about frac14in (6mm) along the bar knock the feed off andturn the lathe off Move the carriage towards the tailstock sothat you can measure the bar Continue making this cut andmeasureuntilthesizeiscorrectThenrunthetoolalongthefulllengthof the jobWindthecarriagebacktowardsthetailstockand take a finishing cut or two at the same setting ThediametershouldnowbetheexactsizerequiredIt is not difficult to turn accurately it just takes a little

patienceandpracticeThemoreturningyoudotheeasieryouwill find it is to hold accurate limits If you turn everythingaccuratelywhetheritneedstobeaccurateornotyouwillsoonlearntoturnwithinathouorsowithoutanyproblems

Measuringtheheightofthebarabovethecrossslide

Now we need to make a tool height setting gauge Cut alengthofbarjustoverthedimensionsyouwrotedownandfaceone end turn it round in the chuck and face the other endMeasurethelengthandfindouthowmuchyouhavetotakeoffit to give the dimension you want Put the bar back into thechuck and bring the tool up to the face of the bar Lock thecrossslideFacethebartolengthbyusingthetopslideindexmovingforwardsafewthouatatimeuntiltherequiredlength

is reached Younowhavea tool height settinggauge suitableforthefrontandreartoolsIf you have an inverted Vee bed lathe or if for any reason

youcanrsquotusetheheightgaugeflatonthebedyoucanputtheheightgaugeonaplateon topof the lathebedwhileyouaresettingthetoolheight

Settingtheheightgaugetothelathecentreheight

Settingtheheightofthetool

Usingthesettinggaugetosettheheightofthereartool

TurningtoaSpecificLengthandDiameter

Nowwewill turnabarwithastepon theendToensure thatthestep isthecorrect lengthwewilluseabedstopThiscanbe as simple as a block clamped to the lathe bed to stop thecarriage moving any further I use a simple home-made bedstopthatdoesallIrequireSetthebedstopthenmovethecarriageuntilittouchesthe

stop and lock it Wind the top slide so that the tool is justtouching the end of the bar and lock the carriage For thisexercise we will make the step 16mm long and 12mm indiameterWindthetopslidealong159mmWecannowroughout thestepateachendTurn theenddown toabout02mmabove the finisheddiameterbywinding thecarriagebackandforthYoucanusethe fine feedbutmakesureyouknockthefeed off before the carriage reaches the stop and finish up tothestopbyhandWindthetopslidealongtheremaining01mmto12mmandfinishthediametertosizeandlengthtakinglightcuts as previously Donrsquot forget to clean up the face of theshoulderyouhavejustturnedIfyouneedtouseabedstopatthetailstockendofthelathe

asimplemethodofdoingthisistouseabarplacedonthelathe

bed against the tailstock The bar acts as a stop when thecarriageiswoundbacktowardsthetailstockThistailstockendbed stop is useful when you are turning a groove in acomponentandyouneedstopssetatboth theheadstockandtailstockendsofthelathe

Ahome-madebedstop

TurningWorkontheOutsideoftheInsideJaws

Theoutsideoftheinside(drill)jawsareusefulforturninglargerdiameterwork that is too large to fit inside thedrill jawsThiswillmostoftenbe in the formofa flywheelcastingFlywheelswithsixspokesareidealforturninginathree-jawchuckasthespokes can fit between the chuck jaws Ideally you need totighten up the flywheel until it is tight but not so tight as todistorttherim

TurningasteponabarusingthestopThebarisheldinthethree-jawchuckandsupportedwiththetailstockcentre

Ausefultailstockendbackstopmethod

Holdingaflywheelinathree-jawchuck

Holdingaflywheelintheoutsidejaws

To ensure concentricity you should do as much work aspossibleonthecastingatthesametimeYoushouldbeabletoturntheoutsiderimofthecastingfacetherimfacethebossand drill bore and ream for the crankshaft all at the samesettingAllyouneedtodothenistofittheoutsidejawsreversethecastinginthechucktapitgentlybackontothestepsoftheoutsidejawsandfaceacrossthesecondsideoftherimandthehubUseabitofshimtoprotecttheflywheeldiameterItdoesnotmatter if the flywheel runs exactly true or not as you areonlyfacingitparallelandtowidthnotturninganydiametersto

size

UsingtheSoftJaws

Soft jaws are very useful when a component has to run deadtrue in the jaws for example when making something like agrindingspindlewhereconcentricityisimportantSoftjawslikelytobefoundinthehomeworkshoparesimple

rectangles of steel with the scroll and groove formed directlyintothesoftjawsAnothertypeofjawyoumaycomeacrosshasa grooved pattern in the main jaws that matches a similarpattern in theactualsoft jawsThesoft topsof these jawsareusually interchangeable They are more likely to be found onlarger chucks but you could make your own version for thesmallersizesofchuckifyouwishThemain use of soft jaws is for second operationwork for

examplewhenyouhaveturnedacomponentcomplete fromabitofbarandparteditoffNowyouneedtoholdthecomponenttruetofinishoffthesecondendYoucandothisbyboringoutthechuckjawstotheexactdiameteroftheworkpieceToborethesoft jawstheyshouldbetightened inthesame

direction as they will be tightened in use so that they areoperatingonthesamepartofthechuckscrolleverytimeIfyouhaveathincomponenttomachinefitthesoftjawstothechuckandtightenthejawsontoabitofbarheldinthechuckBesureto leaveenoughspace in frontof thebarsoyoucanbore thejawstofitthework

BoringsoftjawstofittheworkThejawsareclosedontoanoddmentofbartoturntheshallowregistersothatittakesthework

AlwaysusethesamechuckkeyholewhentighteningupthejawsThisappliestoanythingyoudowithaself-centringchuckStampacrossoracentrepopmarkagainstoneof the jaws IsuggestdoingthisnexttojawNo1butanyonewilldoaslongas you always use the samemarked hole Youmight as wellmarkallyourself-centringchucksinthesamemannerCarefullyborethejawstotheexactdiameteroftheworkto

be machined Try to get it exactly on size Undo the jawsslightly remove the bar and replace it with the workpiecewhichshouldnowrundeadtrueAusefulmodificationtothesoftjawsistodrillandtapahole

inthemiddleofthejawsandfitanAllenscrewtoeachholeIfyouwant toholda longbar in thesoft jaws it isnoweasy toboreallthewaythroughthejawsratherthanjustboringastepor part way through All you need to do now is find a disc ofmaterial to put into the chuck ensuring there is sufficientmaterialleftontheinsideedgesofthechuckjawstoborerightthroughtotakethebar

Holdthedisconthescrewheads ifnecessarydrillthediscbeforeboringBorerightthroughthediscandthejawsuntilyouarenearlytosizeatwhichpointyoucanborethroughthediscand test the resultingborewith theworkpieceMakesureyouclean the bore thoroughly before trying the workpiece sinceloose dust can make the hole seem smaller than it really isWhentheworkpieceenterstheborefinishboringrightthroughthe jawsgo througha coupleof timesat the samesetting totakeoutanyspringintheboringbarYoucannowremovethedisc clean the jaws and put the workpiece right through thechuckcheckingthatitrunsdeadtrueThisoperationmaysoundtimeconsumingforasingle item

but if you have several components to make it will save aconsiderable time on setting up each bar individually to runtrue

BoringsoftjawsusingaringThesoftjawshavethreeAllenscrewsthatarecloseddownontotheringwhileboring

TurningtheoutsideofthesoftjawsusingaringThesoftjawshavethreeAllenscrewsthatareopenedupontotheringwhileturning

NowthescrewsareinplacewecanworktheotherwayroundandholdcomponentsontheoutsideofthejawsTodothisyouwillneedaringofasuitablesizeontowhichyoucantightenthejawswith the jaw loading acting outwards so any componentyouputontheoutsideofthejawswillberunningconcentricallyThiswill be ideal for itemssuchas tractionenginewheel rimsandotherlargehollowortubularworkpiecesOne other use for soft jaws is to hold irregular-shaped

components Put a piece of bar into the soft jaws and bore aholeofanysizeand thencleanup theboreso thatallof thejawsare true Transfer the chuck to themillingmachine tableandclampitdownUseatestindicatortocheckthattheholeinthechuckistrueYou can now mill a nest to take any irregularly shaped

component confident that when the chuck is returned to thelatheitwillberunningtrue

Plungertypedialtestindicator

Levertypedialtestindicator

DialTestIndicators

Therearetwomaintypesofdialtestindicatortheplungertypedial test indicator as its name suggests works on a plungerprinciplewhilethelevertypedialtestindicatorhasastylusonthe end The lever stylus is usually ball-or pear-shaped and isfixedtothedialtestindicatorwithafrictionfitmeaningthatitcanbemovedupanddownontheendofthedialtestindicator

throughawidearctoputitintothebestpositionforuseThe plunger type dial indicator usually has a maximum

plungermovementoffrac12in (12mm)butplungermovementsofupto2in(50mm)areavailableTheplungertypedialindicatoris non-reversing and needs an adaptor to enable it to clockholes true Instead of a stylus it has an interchangeable endoften with a ball fitted various interchangeable ends areavailableoryoucanmakeyourownThe lever dial test indicator has a much smaller range of

travelarangeof0008in(02mm)isverycommonItisusuallyeither self-reversing (itmoveswhen in contact with theworkdependingonwhichwayitismoving)oritmaybereversedbyusinga lever on the sideof thedial test indicator both typesarequite commonSince the stylus isdelicate combinedwithitslimitedtravelrangeyoumustbeverycarefulnottobreakitAplungerdialindicatorcanbeusedasadirectreadoutofthe

travel and will be found to be very accurate Owing to therelativelylongtravelifyouwantedperhapstooffsetthecentreofabitofbar in the four-jawchuckby0125in (318mm) thiscanbedonebyturningthechuckbyhandandsettingthebaruntil the indicator travel shows 0250in (635mm) which is0125in (318mm) offset The lever dial test indicator is of nouseforgivingdirectreadingslikethisbutshouldbeusedasacomparatorwherethereadingtakenisforexamplezeroatallpointsofthetravelThedial test indicator is usuallymounted on amagnetic or

vacuum base but is sometimes fixed to a block that can beclampedtothelathemostoftenonthecrossslideSometimesthedialtestindicatorcomesasacompletekitincludingvariousmountingcomponents

Clockingtheendofacastinginafour-jawchuck

Four-jawChuck

To set thework up in an independent four-jaw chuckwe firstneed to know what part of the workpiece should be on thecentre If theworkpiece is a castingwemay have an outsidediameter or a hole that needs to run true in this case wewould put a dial test indicator onto the work and adjust thechuckalittleatatimeuntilthediameterrunstrueDonotturnthe chuck with the indicator in the hole Instead wind thecarriage forwards until the clock enters the hole and take areadingWind thecarriageback rotate thechuck90degreeswindthecarriageforwardandtakeanotherreadingAdjusttheworkinthechuckuntilitrunstrue

WhereacastingisstickingoutashereyoushouldtrytosupportthecastingwitharunningcentreThiswillhelptostopthecastingshiftinginthechuck

LatheCentreFinder

If there isnodiameterorholeyoumayhave tomarkout thecentreontheworkusingaheightgaugeandcentrepopitwithacentrepunchThenyoucanuseawobblerandatestindicatortosettheworktrueItwasoncepossibletogetalathecentrefinderconsistingof

a bar about 6in (150mm) long pointed at both ends with auniversaljointabout1in(25mm)fromthefrontendInusetheshortfrontendgoesinthecentrepopoftheworkinthechuckWhen you rotate the chuck by hand the pointed short endfollows the eccentricity of the centre hole which ismagnifiedaboutsixtimesatthetailstockendYouthenjusthavetoadjustthechuckuntilthetailstockendisrunningtrueatwhichpointthe centre in the work will also be running dead true I donrsquotknow anyone who makes these and second-hand ones areextremelyrare

Asimplehome-madecentrefinder

You can make a simple version of this that works well byusingamillingmachinepointedcentrefinderThisisaparallelbarwithaseparatemoveablepointedendThetwocomponentsare held together with a spring inside You need the pointededge finder a Morse taper parallel adaptor (the Morse tapershould fityour tailstock)aspringandashortstubofbar thatwillfitinsidethetaperedholderrsquosboretostopthespringgoingrightthroughPuttheshortstubofbarintothetaperinsertthespring follow up with the centre and put the Morse taperadaptorintothetailstockBringthetailstocktowardsthechuckuntil the centre of the centre finder is in the centre pop ThespringwillholditinplaceTousetheimprovisedcentrefinderput a dial test indicator onto the parallel part of the centrefinderrsquospointandrotatethechuckbyhandThepointwillrotateeccentricallyadjust thechuckuntil thecentre finderrsquospoint isrunningtrue

Usingascribingblockwithadialtestindicator

Move the tailstock along the bed until the point of thewobblerisinthecentrepopontheworkPutthetestindicatoronthefrontdiameterofthewobblerandadjustthechuckjawsuntilthewobblerisrunningtrueWhensettingupacastingorsomethingsimilarwherenotall

of the diameters are machined you should use the dial testindicator on diameters thatwill not bemachined such as theinsideofaflywheelrimWhenyouhaveturnedallthefinisheddiameters they should then be true with the unmachineddiametersSetting work in the four-jaw chuck depends on the

componenttobemachinedIfyouareusingroundmaterialyoucansetittoruntrueusingadialtestindicatorHoweverifyouaresettingaroughcastingthevariationofsizeandroughnessofthecastingsmaywellbeunsuitableforadialtestindicatorThere are alternativemethods of settingwork up in a four-

jawchuckespeciallyforcastingsOneofthesimplestmethodsis toholdasquarebar in the lathetoolholderandusethis tosetthejobtrueInuseyouwindthebaruptotheworkandsetthedial tozeroorotherwisemakeanoteofwhere it isWindthebaroutorawayfromtheworkTurnthechuck180degreesand wind the bar up against the work again You can

immediatelyseewhichwaythebarneedstomovesothatitisrunningtrueAdjustthecastinginthefour-jawchuckandmovethecastingtowardsthecentrepointRepeatuntilthecastingisrunning true This method is also useful if you are setting asquarebar to run true Justcheckeach faceof thesquarebarwiththebitofmetal

Settingacastingbyusingasquarebar

StickyPinMethod

An alternative the sticky pin method is especially suited tolocomotive wheels or flywheels An ordinary household pin ismounted in plasticine or Blu-tack perhaps stuck on the lathetool and is arranged to point to the inside diameter of thewheelor flywheel thearea that isnotmachinedbut is leftascastAdjustthecastinguntiltheunmachinedfaceisrunningastrueasyoucangetitandthewheelisreadytoturnThestickypinmethodisalsousefulforsettingupworkthathasachuckingspigot such as a locomotive smokebox door Just hold thechucking spigot in the four-jaw chuck and adjust the castinguntilitrunstrueontheoutsidediameterandthefrontface

Usingacommercialstickypintosetworktrue

Themethodsofcentringworkinthefour-jawchuckthathavebeen discussed are also suitable for setting work true on thefaceplate The next chapter looks at turning between centresandusingthefaceplate

6TurningbetweenCentresandFaceplateWork

Thischapterdealswithbasicturningbetweencentresandthenintroduces turning with the work mounted on the lathefaceplate

Headstockcentreanddriverplate(alsoknownasacatchplate)

TURNINGPLAINBARSBETWEENCENTRES

The most basic way of holding work for turning is between

centres Turning between centres is literally holding thecomponenttobemachinedbetweentwocentreseachofwhichhas a 60-degree included angle The headstock centre usuallygoes round with the headstockmandrel although some olderlatheshadanon-rotatingcentreandthedrivetotheworkwasbyapulleymountedontheworkThetailstockcentreisoftenafixedcentrethatdoesnotgoroundalthoughcentreswithballbearingscalledrunningcentresarereadilyavailable

Tailstockplaincentre

The component to be turned usually a shaft has a female60-degreecentreinbothendsthatisusedtosupporttheworkThe work can be turned round between centres so that bothends of the shaft can be machined Because the work ismountedbetweencentresbothendsoftheworkwillbetruetoeachother

Tailstockrunningcentreso-calledbecauseitrunsonballraces

CentringtheBar

FirstwehavetoputthecentresintoeachendofthebarIfthebarisshortsayuptoabout6inlongholdtheworkinthethree-jawchuckanduseacentredrillinthetailstockdrillchucktoputacentre intothebarAcentredrill isashortdrillwithasmallpilot on the end that has a 60-degree taper to the bodydiameterAbettermethodof centring thebar especially longbars is by using a three-jaw chuck and the fixed steady Thebarisheldinthethree-jawchuckwiththeotherendsupportedin the fixedsteadyand thecentre is formed in theendwithacentredrillAusefultoolthatcanbeusedtofindthecentreoftheshaftis

thecentresquarewhichisametalbladewithaVeeonitthatlocatesonthediameterofthebarMarkalineacrosstheendofthebarwitha scriber turn the centre square90degreesandthenscribeanotherlineWherethetwolinescrossisthecentreof thebar Tomake it easier to see the scribed linesblackenthe end of the bar with a permanent felt tip marker beforescribingCentrepunchthepointwherethetwolinescrossandput a 60-degree centre in each end of the bar using a centre

drill in a power drillHold thebar in a bench vicewhile doingthisPutacentredrillintothetailstockdrillchuckandinsertthebar in the three-jaw chuck Make sure the lathe is on a lowspeedabout300rpmwindthetailstockinandjustlightlycleanupthecentreholewiththecentredrilltotrueitupAnotherusefultooltofindthecentreofabarisabellcentre

punchThiscomprisesaconewithacentrepunchinthemiddleIn use place the bell end on the end of the bar and tap thecentrepunchwithahammertomarkthecentreTheendofthebar though needs to be reasonably square if using the bellpunchmethodThere are other similarmethods of centring bars but those

givenherewillbealltheturnerneedstolearn

Turningbetweencentres

Centringthebarusingthefixedsteady(Notethatthefrontclampisnormallydoneupwhileinuse)

Asimplecentresquare

Crosssectionofbellcentrepunch

MachiningtheBar

NowweneedtomountthebarbetweencentresThisissimplyamatterofputtingthebarbetweencentresandtighteningthetailstocksoitislightlypressingintothecentreintheendofthework To drive the work a carrier is fixed to the shaft andengagesapininacatchplatemountedonthelathemandrelAcatchplateissimplyablankdiscwithapinstickingouttodrivethecarrierthat isfittedtotheworkThecarrier isfittedtotheworkusinganAllenscreworboltTostopanymovementofthebarinrelationtothecatchplatethecarriercanbewiredtothecatchplatepinThiswill stop thecarrierand thework flappingaboutItisparticularlyimportanttostoptheworkfrommovingin relation to the catchplate when screwcutting betweencentres

Facingoffabarusingthehalfcentre

Nowthatthebarissafelymountedbetweencentreswecanstart turning it tosizeNormally the first thing todo is to facetheendsofthebartothefinishedlengthDecidewhichendofthebarhastheshallowercentreWewillmachinethisendfirstYouwillneedahalfcentreso-calledbecausealmosthalfofthecentre is missing This means the lathe tool can reach rightacrosstheendoftheworkwithouttouchingthehalfcentreWhenusinganyfixedcentreinthetailstockputabitofoilor

grease into the centre before use and top up as necessaryLightlywindthetailstockbarrelagainstthecentreandlockthebarrel so it canrsquotmoveSwitch the latheonandwind the toolacross to clean up the end Reverse the work and clean theotherendupat thesamesettingBothcentresshouldnowbethesamedepthMeasuretheoveralllengthofthebarTakethefinished length required from the overall measurement youhavejustmeasuredDividethisbytwoandthisishowmuchweneed to take off each end of the shaft so it finishes at therequiredlength

Askimmedbar

Ifyouhaveonechangethetailstockhalfcentretoarunningcentre if you donrsquot have a running centre change to a fixedcentreThehalfcentreshouldonlybeusedwhenfacingtheend

of the bar We will nowmachine the rest of the bar For thepurposeofthisexamplewewillassumethebarhasafinisheddiameter in themiddle with a step at each end First we willmachine the overall diameter to size To do this we need toskimthediameterandcheckthesizeTakeafinecutalongthebarusingthefinefeedifyouhaveoneMeasurebothendsofthebar Ifyouhavesetthelatheupcorrectly(seeChapter2)thebarshouldbeparallelIfitisnotadjustthetailstockbeforecontinuingAssumingthebarisparalleltakeanothercutortwosothatyouareabout01mmlargerthanthefinisheddiameterNowmove the tool in until almost at finished size and take alight cut about 10mm long along the bar Repeat this cut toensure the tool is notpushingoffMeasure thisdiameter youwill probablyhave towind the tailstockbarrel back toget themicrometerontotheendofthebarOnlymovethebarrelbackdo not slide the entire tailstock backMeasure the bar to findouthowmuchtoremovefromthediameterTakeanothershortcutandcheckforsizeWhenthebariscuttingtosizemachineall thewayalongYouwillprobablyhave to take twoor threecuts at the same setting until the bar ismachined to finishedsizeNowwewill turn the stepson theends Toensure that the

stepsare thecorrect lengthwewilluse thebedstopSet thebedstopthenwindthetopslidesothatthetoolisjusttouchingthe end of the bar For this exercise we will make the steps12mm long Wind the top slide along until the tool is justtouching the end of the turned bar Wind the top slide along119mmWecannowroughoutthestepateachendTurntheenddowntoabout02mmabovethefinisheddiameterYoucanusethefinefeedbutmakesureyouknockthefeedoffbeforethecarriagereachesthestopandfinishuptotheendbyhandRepeat for the other end Wind the top slide along theremaining01mmto12mmandfinisheachendinthesamewayasyoufinishedthemaindiameterDonrsquotforgettocleanupthefaceoftheshoulderyouhavejustturnedCongratulations you have just turned an accurate shaft

Donrsquotworryiftheshaftisatinybitundersizeyoucanprobably

makethematingholestofit

Thefinishedshaft

Usingachuckandarunningcentre

Usingthemethodsetoutaboveyoushouldnowbeabletoturn any shaft you require within the capacity of the lathe Avariationoftheabovemethodwheretheshaftissingle-endedistoholdoneendinthethree-orfour-jawchuckandsupporttheotherendwithacentreinthetailstock

Alargefaceplatesmalleronesareavailable

FACEPLATEWORK

Another basic way of holding work is on the faceplate Thismethod is used when the component is too large or isawkwardly shaped andwould be difficult to hold in a three-orfour-jaw chuck Usually the work is clamped directly onto thefaceplate often with a packing piece behind it to protect thefaceplateThefaceplateshouldbeflatandtruesothefirstthingtodo

whenyougetthelatheistocheckthefaceplatewithadialtestindicatorCarefullycleanthemandrelnoseandtheinternalholeinthefaceplateMakesurethemandrelcanturnfreelybyhandwith the lathe switched off and check that the face of thefaceplateisrunningtrueasclosetotheouteredgeasyoucanget If it is runningtrue runthetest indicatoracross the frontfaceofthefaceplatethisshouldbetrueaswellIfthefaceplateis running out itwill need to bemachined Put the lathe intobackgear if ithas it (topbackgearwillprobablybe fine)Youwill need a carbide-tipped tool ideallywith a small 45-degreechamferonthetipBringthetooluptothefaceplateand lockthe carriage Next you need to lightly face the faceplate right

acrossitsdiameterIfyouhaveapowercrossfeeditwillmakelight work of this but if not you can feed across by handFortunatelymost faceplateshavea series of rings on them toaid in setting up the work Machine the faceplate from theoutsidetothefirstringandstopforarest feedtothesecondring and so on until finished Depending upon how badly outyourfaceplateisyoumayhavetodothismorethanonceuntilit iscleanedupbutwhen it isdoneyouwill rarelyneedtodothisexerciseagain

Machiningaholeinablock

Asmentionedpreviously the ringsmachined on the faceplateareguidestohelpyousetuptheworkThiswilldoiftheworkisaroundcomponentbutweneedadifferentmethodiftheworkis square Take a block of metal for example that has beenmachinedalloverWewanttomachineaholeinit2infromoneedgeand1in fromanother edgeMarkout thepositionof theholeandcentrepunch it Put adeadcentre into the tailstockholdtheblockontothefaceplatebringthetailstockuptowardsthechuckandlockitWindthetailstockbarrelandcentreuptothe component and engage with the centre pop Lock thetailstock barrel Clamp the block to the faceplate using somepackingpiecesandfourclampsontheblockTheholeisnowoncentreandwecanmachineitinthecorrectplaceIf we need more than one hole placed accurately in the

componentwecanusetoolmakerrsquosbuttonstoensuretheholesare in the correct place Toolmakerrsquos buttons usually come insetsof fourOnebutton isusually longer than the rest soyoucanstillclockthediameterwhenitisclosetoanotherholeSetsare often available second-hand on eBaywhile they probablyhaveanobscureAmerican threadyoucanclamp themto theblock using your own BA or metric screws together with awasher

Settingupthefaceplateusingthetailstock

Asetoftoolmakerrsquosbuttons

Tofitthemtothecomponenttobeboredmarkoutdrillandtap holes in the approximate positions where the holes areneeded If you need a pair of parallel holes place thecomponentonasurfaceplate looselyfitthebuttonsandpushthem down onto a parallel or similar block of the correctthicknessandnipthescrewsupThespacershouldbesmallerthanrequiredbyhalfthediameterofabuttonIftheholesneedtobeacertaindistanceapartuseaspacer

of the correct size between the buttons (Remember tomake

thespacersmallerbyonediameterofthebutton)

Settingupacomponentusingtoolmakerrsquosbuttonstogetafixeddistancefromtheedgeofacomponent

TherearelotsofdifferentwaystosetthespacingofbuttonsItismainlyamatterofcommonsenseCastingsandflatcomponentscanbeboltedtothefaceplate

for machining A typical example of a flat component is aneccentric strap This type of component is usually made of acomponentthatiscutinhalfandboltedbacktogetherAholeisthenboredinitonthecentrelinetofittheeccentricThistypeofcomponentisoftendifficulttoholdinthelathechuckandisprone to distortion Castings are often too large to fit into alathechuckandso the faceplate iscalledon toundertake theworkAcastingcanoftenbebolteddirectlytothefaceplatetofacilitateeasymachining

Settingupacomponentusingtoolmakerrsquosbuttonstogetafixeddistancebetweenthecentresofacomponent

Work on the faceplate is often an odd shape or is set off

centreThiscauses it tobeunbalancedandasaconsequencethe lathemayvibratewhile thework is turningTocounteractthis tendency the faceplate should be counterbalanced byboltingweightsontoitAusefulsourceofweightsisthelathersquoschange wheels By bolting a change wheel or two onto thelightersideofthefaceplateyoucanbringthewholeassemblybackintobalanceAfterboltingthechangewheelsonspinthelathe by hand to check the balance The faceplate should notshowatendencytostopatoneparticularpointWhenyouarehappy that the faceplate is in balance the work and balanceweightsareboltedontightlyandsothattheworkdoesnotfoulthe lathewhen turnedbyhand switch themachine on in lowback gear to check for vibration Depending on what you areturning you should be able to run in top back gear or evenbottomdirectspeed

Asimpleclampsetisveryusefulwhenmachiningacastingonthefaceplate

TurningaFlywheel

Oneofthemainusesofafaceplateisturningalargediameteriron casting typically a flywheel or a locomotive wheel for asteamengineTheflywheelshouldbemountedsothattheinneredgeoftherimandtheouteredgeofthehubruntrueIfeitherofthemrunsoutitwouldbebetterthatthehubrunsoutasthe

rimwillbemorenoticeableonthefinishedengineClamp the flywheel down with some packing under the

spokessothatyoucanturnrightacrosstherimBecarefulthatyouclamptheflywheeltightenoughsothat itdoesnotmovebutnotsotightthatitdistortsRoughturn theoutsidediameterand facetherimusingthe

backgearUsingadirectdrivespeeddrillandborethecentrehole and either finish off with the boring tool or use a reamDonrsquot try reamingwithout boring the chances are that if youdotheholewillnotbetruewiththerimasthedrillprobablydidnotcutanaccurateholeDropdowntothetopbackgearspeedface the rim and turn the outside of the rim to the finisheddiameter Turn the flywheel over and finish the other face towidth

Astubarborsuitableforcentralizingalocomotivewheelorflywheel

TurningLocomotiveWheelFlanges

LocomotivewheelflangescanbeturnedonafaceplateYoucanpurchase blank end Morse taper arbors that fit into theheadstocktaperFitoneoftheseandturnaspigotonittotake

thewheel bore Thewheel bores should all be the same sizebut if they are different sizes machine the spigot to fit thelargestboremachinetheflangeonthatonethenmachinethespigotdowntofitthenextonemachinetheflangeandsoonIdeally the wheel bores should all be the same size but if

theyarenotproceedas followsSkimtheoutsidediameterofthe wheel flangemeasure and take it to the correct finishedsizeMovethelathetoolinbythedepthoftheflangeandturnthe tread Deal with all wheels like this machining all of theflangeoutsidediameterstothesamesizemovinginthecrossslidebythesameamounteachtimesothatallthetreadsendupthesamesize

UsingtheKeatsVeeangleplatetoturnaneccentriccomponent

KeatsVeeAnglePlate

TheKeatsVeeangleplate ismountedon the faceplateand isusedtoholdroundbarsquarebarandmiscellaneouscastingssuch as cylinders and steam chests The angle plate can bemountedanywhereonthefaceplateaslongasthelathecanbe

rotated safely and is in balance When spun by hand thefaceplateshouldnotshowatendencytostopatanyparticularplacewhenrununderpowerthelatheshouldnotvibrateAswellasholdingbarandcastingsforturningtheKeatsVee

angleplateisveryusefulformakingeccentriccomponentssuchastheeccentricsforasteamengineTo turn an eccentric use a test indicator to check that the

roundbarisrunningreasonablytrueWhenthisissatisfactoryyoucanturntheoutsidediameterofthebartofittheeccentricstrap (or component) including any step or groove requiredNextoffsettheKeatsVeeangleplatebytheamountyouwantthe eccentric lsquothrowrsquo to be Use the dial test indicator tomeasure the offset of the outside of the eccentric The offsetshouldbetwicethethrowYoucannowdrillboreandreamtheholeintheeccentricYounowhaveenoughbasic knowledge to carryout turning

between centres andwork accurately on the faceplate In thenext chapterwewill lookat holdingwork in a collet andonamandrel

7ColletsandMandrels

Thischapterexplainsallaboutholdingworkinacolletandhowyou canmake and use several different types of mandrel forworkholding

ERcollets

USINGCOLLETS

Quite a few different collet systems are to be found inworkshops Some are used for holding tools such as millingcutterssomeareusedforbarorworkpieceswhilesomemaybeusedwithbothbarandworkpiecesOne of the commonest is the ER collet which comes in

severaldifferent sizeseachhavingadifferent largediameterTheERcolletsystemallowsupto0039in(1mm)collapseofa

colletalthough in thesmaller sizesyoucanbuy thecollets in05mmincrementsA16mmcolletforexamplewillholdroundmaterialdownto15mmdiameterWhatevertheERcolletsizetheyallappear togodownto1mmminimumwhichwillclosedownto05mm

ERcolletadaptor

TherearemanytypesandsizesofERholderavailableAlltheusualMorse taper shank sizes are available and you can alsobuyvariousdiametersofextendedparallel shankholdersTheproblemwiththeseisthattheyaregreatforholdingtoolsthathave a short shank but because you need to use the holderwithadrawbaryoucanrsquotputlongbarstockrightthroughthemTo overcome this for lathe work you can also buy ER colletholdersdesignedtobefittedtoachuckbackplatethatyoucanmachine to suit your lathe so ensuring good concentricityBecause they donrsquot use a drawbar you can fit bar stock rightthroughandintotheheadstockmandrel

ERcolletadaptorfittedtoabackplateIalwaysleavebackplatesoversizesoIhavesomethingwithwhichtoclampthemdownwhenusedonamillordrill

When buying new and second-hand ER collets make surethey have the retaining groove near the nose end The older(andobsolete)EandEScollet typesdonothavetheretaininggrooveandarenotinter-changeableYouaremostlikelytofindEandEScolletsincludedwithasecond-handUnimatlatheDraw-in collets are usedwith a drawbar or collet tube The

drawbardrawsthecolletuptightbydrawingit intothelathersquosmandrelbyabar that runs through thecentreof themandreland screws into the centre of the collet Thismeans that youcannotputbarstockrightthroughthecolletToovercomethissome Morse taper collets use a hollow draw tube the collethaving an external thread tomatch the internal thread of thedrawtube

Draw-incollet

Special collets are made for the Myford ML7 Super 7 andML10 lathes These are Morse taper collets but rather thanhavingadrawbartheyareclosedwithanoseringthatfitsoveragrooveinthecolletThenoseringtightensthecolletintotheheadstockmandrelrsquos Morse taper It is extracted after use byundoing the nose piece which draws the collet out from theMorsetaperbythenosegrooveImperialandmetriccolletsareavailableuptofrac12in(12mm)diameterDead lengthcolletsareavailable that fit intoanattachment

usually fixed to the front of the lathersquosmandrel These colletsarecalleddeadlengthbecausetheydonotmovelongitudinallyunlike draw-in collets You are more likely to find collets likethesesecond-handratherthannew

BoxedsetofMyfordcollets

Deadlengthcollet

AvariationofthedeadlengthcolletistheCrawfordMultiborecolletThissystemhascolletsmadeofsegmentsheldtogetherbyspringsThecolletsareofvariablediameterandhavequitea

largeclosurerangeTheyaremorelikelytobefoundonalargercommercial lathe although you can get collets for smallermachinesWatchmakerrsquoscolletscanbeused inmost lathesbymaking

an adaptor for the headstock and a drawbar (or tube)Watchmakerrsquos collets are very accurate and can go down toverysmallsizesbuttheyhavelimiteduseinmostworkshopsYou can get a special watchmakerrsquos spindle for the EmcoUnimatlatheandthereisalsoaversionoftheCowellslathetheCW90thattakeswatchmakerrsquoscolletsFormost of thework carried out on the lathe youwill find

thatanERholder thatmountsontoachuckbackplate ismostuseful

Simpleexpandingmandrel

Simpleplainmandrel

MAKINGMANDRELS

There are several types of mandrel in common use inworkshops The most common is probably the expandingmandrelwhichcaneasilybemadeinanyworkshopInitsmostbasic form it is a bar turned to a size to fit the bore in theworkpieceItisthenthreadedwithataperedtapandslitat90degrees togive foursegmentswhichare thenexpandedbyascrewfittedintotheendofthemandrelAnother common mandrel is the tapered mandrel This is

usuallyalsquobetweencentresrsquomandrelandisoftenmadetotaperfromjustacoupleofthouovernominalsizetoacoupleofthouunder nominal size It is usually hardened and has a groundfinishTheworkpieceisheldinplacebybeingpushedontothemandreluntilitistightToremoveitjustpressitbackoutthewayitwentinWhereconcentricityisnotquitesoimportanttheworkpiece

canbeputonaplain turnedmandrelandtightenedupwithaboltandflatwasherExpandingmandrelsarealsomadecommerciallybutasyou

need a mandrel for each individual size of hole it can getexpensive if you need more than one or two different sizesCommercialmandrelscanbeobtainedwithMorsetapershanksto plug straight into the headstock Thismethod ensures thatthe mandrel should run dead true assuming both the Morsetapermandrel and theMorse taper in the headstock are bothcleanandfreefrommarksorswarfYou can also purchase Morse taper arbors with blank end

pieces from which to make your own mandrels First we willmake an expandingmandrel from a blank Morse taper arborYouwillneedtoturnthearbordowntofittheworkpieceboreIusually turn themandrelabout0010in (0025mm)oversize tostartwithandthenIdrillandtapthearborwithataperedtapThe drilled hole can go quite deep but the tapped hole onlyneedstogoinuntilthelockingbolt isabouthalfwaydownthelengthwheretheworkpiecewillsitPut the mandrel into the vice and cut along the mandrel

making four cuts around the circumferenceRetap thehole to

cleartheswarf fromthethreadandputthemandrelback intothe headstock taper Now you can lightly nip the screw up toexpandthemandrelslightlySkimthemandrel to finishedsizeuntil the workpiece will fit on without shake You can nowfurther tighten the screw so that the workpiece tightens ontothe mandrel When you slacken the screw the workpiece willcome off easily as you have skimmed it while it was slightlyexpandedYoucanmakeanexpandingmandrelfromabarheldin the three-or four-jawchuckorperhapsacollet inasimilarway Ifheld inachuck itmaynotgoback true ifyouneed touseitagainsoifpossibleyoushouldholdthearborinacolletFor aplainmandrel turn thediameter to fit theworkpiece

anddrillandtapforacapscreworaboltThereisnoneedtosplit this type ofmandrel You simply put the workpiece ontothemandrelandholditonwithaflatwasherAgainitdoesnotmatterwhetheryouuseabarinachuckorcolletorifyouusea Morse Taper blank arbor Arbors are very useful in theworkshop If youmake them fromMorse taper blanks or holdtheminacollettheycanbeusedoverandoveragain

8TaperTurningandLatheAccessories

Thischapterexplainshowyoucanturnataperusingatopslidetheuseoffixedandtravellingsteadiesandformtools

Turningataperwiththetopslide

TAPERTURNING

SometimesyouwillhavetoturnataperintheworkshopThatisa fairly easy jobWhat ismore difficult however is having toturnmatchingmaleandfemaletapers

Themethodyouaremostlikelytouseintheworkshopistoturn the two tapers with the top slide You should be able toturna taper longenough foraMorsetaperusingthismethodThemostimportantthingwhenturningtapersistoensurethatthe tool tip is at the exact centre height of the lathe This isbecause the taper will vary if the tool is not dead-on centreheightProbably the easiestmethod of turning aMorse taper is to

useadial test indicator toclocka lathecentreof therequiredMorse taper between centres The smaller end of the tapershouldbeatthetailstockendofthelatheThetopslideshouldbewoundalongthetaperby itshandwheelwhilethecarriageremainslockedThetopslideshouldbeadjustedangularlyuntilthedialtestindicatorreadszeroallthewayalongNowyoucanfinish turn the external Morse taper using an internal MorsetapersleeveasagaugetocheckthattheangleiscorrectTodothis make marks with a felt tipped pen along the taper andcheck that the test sleeve rubs evenly all the way along themaletaperAdjustifnecessaryuntilyouhaveaperfectfitToturnthematchingfemaletaperthelargeendofthetaper

willbeat the tailstockendand theboringbarwillbe invertedandcuttingon thebackof theholeDoing thismeans thataslongasbothofthetoolsareatcentreheightthetapersshouldmatchWecanusethemaletaperthathasjustbeenturnedasatestbarBoreoutthetaperverycarefullyyouwonrsquotneedtoremovemuchmaterial before the test taper goes too far intothe finishedbore Testwitha felt tippedpenuntil youhaveaperfectfitYou can turn any taper you need this way you are not

restrictedtoMorsetapersAnothermethodmostoftenusedforlongshallowtapersistouseataperturningattachmentTheseattachments are often available as extras on higher qualitylathes They comprise a slide mounted onto the back of thelathe Often the guide is dovetailed with a sliding blockattached to the cross slide to guide the tool on a taper ThedepthofcutisusuallyputonusingthetopslidesincethecrossslideisusuallydisconnectedfromthefeedscrewInthiswayit

isfreetomoveinandoutcontrolledbytheguide

Taperturningattachment

Settingthetopslidebyclockinganexistingtaper

Anothermethodweshalllookatfortaperturningistooffsetthe tailstock on its base This will make the work turnedbetween centres become tapered either large or small at thetailstockenddependingonwhichwaythe tailstock isoffset ifsettowardsthebackofthelathethediameterwillbelargerat

the tailstock end if the tailstock is moved to the front thetailstockendwill be smaller indiameter Theamountof taperthatcanbeturnedinthismannerislimitedsincetheheadstockandtailstockcentresareoutoflineThe final method of offsetting the workpiece is by using a

boringhead inthetailstockYouneedahome-madehardenedsolidcentrethatfitswheretheboringtoolwouldnormallygo(AsmallUnimatlathesizerunningcentremightbeideal)SettheboringheadsothetooltravelishorizontalYoucanthenoffsettheboringheadcentresocreatingataperThisisthesameassetting the tailstock over but you donrsquot have to realign thetailstockafterwards

Usingthefixedsteady

USINGFIXEDANDTRAVELLINGSTEADIES

The fixedsteady isusedmainly to turn theendofabaror tocentre a workpiece that is too large to fit through the chuckObviously bar stock should not protrude from the chuckmorethan is necessary to work on This is where the fixed steadycomesinThefixedsteadycanbesettothediameterofthebarsothattheendofthebarcanbemachinedsafely

Thesteadycanbesetusingachuckmountedonthistailstockadaptor

Travellingsteady

Settingthesteadybyusingachuckmountedonanadaptor

Onewaytosetthefixedsteadytosizeistoturnabitofbarin the chuck to the same size as the barwewant to use thesteadyonThenwecanmovethefixedsteadyalongthelathebedandfittheworkpieceintothechuckandinthesteadyTheendof thebar nearest to the tailstock shouldnowbe runningtrueandcanbeworkedonsafelyThebarcanbecentredrilledfacedorotherwiseworkedonAn alternative way to set the steady is to support the

tailstockendof thebarwitha threejawchuckmounted in thetailstockAdaptors to take the threejawchuckareavailableoryoucouldmakeyourownJustsupportthebaratbothendsinthethreejawchucksandsetthesteadyfingerstothebarThe fixed steadycanalsobeused to support tubes thatdo

nothaveanymaterialinthecentreThe fingers of the steady need to be lubricated regularly

while inuseThis iseasilydonebydrillinga smallhole in thetopfingerwithacountersinkinsidetheslottotakeoilThetravellingsteady ismostoftenusedwhenturningdown

small diameterbarsor screwcutting long slenderbars It boltsonto the front of the cross slide in line with the chuck and

travelsalongwhenthecrossslideismovedalongthelathebedWhen turning the travelling steady can either be set to thediameterofthebarbeforeturningandtoleadthetooloritcanbesettothefinisheddiameterrequiredandtofollowthetoolNormallythefingersaresetto leadtheturningtoolbut if thebarisroughforexampleifitisdentedorrustyitisbetterforthefingerstotrailtheturningtoolIfscrewcuttingthetravellingsteadyshould lead the toolso that itdoesnotdeflectorwearduetoaburrbeingthrownupbythescrewcuttingtoolSteadies will not be used very often but they are

indispensableontheoccasionswhentheyareneeded

Travellingsteadywithleadingfingers

Travellingsteadywithtrailingfingers

MAKINGASIMPLEFORMTOOL

Youmay often need to produce a particular shape such as aradiusonacomponentTheeasiestmethodtodothisiswithaformtoolAsanexamplewewillmakeasimpleformtooltocutahalfcircleonabarofbrassForaradiusof3mmforexampleweneedtoproducea formtoolusinga6mmdiameterdrillorreamFormaterialwewillusegaugeplateahighcarbonsteelthatcomesintheformofagroundflatbarApieceabout5mmthick and10mmwide is needed although the size is not thatimportantaslongasthegaugeplateisthickenoughtoabsorbanyturningstressesIdeallyweneedataperedreamerthatwillproduce a 6mm diameter hole somewhere along its lengthalthough you could use a parallel 6mm reamer a slot drill orendmillorevenastandardtwistdrillDrill a hole through the gauge plate and open up to 6mm

diameterAim togetagoodsurface finishon thesidesof thehole Hacksaw and file half the hole away to leave the shaperequired on the finish turned component Now we need to

harden the tool although ifweare justdoingacomponentortwoinbrasswecouldprobablygetawaywithouthardeningitHardeningissimpleenoughheattheworkingendofthetool

toredstopheatingandletthegaugeplaterestforacoupleofminutesThiswillgive thegaugeplateachance tochange itsinternalstructureReheattoredandquenchinatubofwaterThisshouldhardenthetoolAlthoughabitbrittle itshouldbefine for making a few components Stone the top of the tooluntil thecuttingedge issharp Ifnecessaryyoucanpolishtheinside of the radius that is going to do the cutting There areseveralmethodsyoucanuse includingapieceofwetanddrypaperaroundabitofbaraverysmallgrindingwheelcalledamounted point or a bit of round bar with fine valve grindingcompoundonitWhicheveryouuseaimforapolishedfinishasthe finish on the turned component is directly related to thefinish on the form tool You canmakeall sorts of simple formtools with gauge plate a typical example being a facing toolwitha30-degreechamfertofaceandchamfernuts

CopytemplatereadytouseMetal

MachiningfromaTemplate

MachiningfromaTemplate

YoucanmachineaprofilefromasimpletemplateThetemplatecanbecutfromgaugeplatewithafileormachinedbutitdoesnot need to be hardened The template could be used tomachinea large radius suchasa smokeboxdoor Inuse thetemplateismountedonablockonthelathebedandthecrossslide is kept in contact with the template by being pushedagainstthetemplatewithaballracefixedtothecrossslideInthenextchapterwewillbelookingatdrillingandreaming

9DrillingandReaming

ThischapterexplainshowtousedrillsandreamersinthelatheTherearemanydifferenttypesofdrillsandreamersTheyareessentialtomakingcomponentsinthelatheWewilllookatthevarioustypesandhowtochoosethespeedsandfeedsforusingthem

Thisdrillchuckrequiresachuckkey

TYPESOFDRILL

Drills are normally held either in the tailstock if they have aMorsetaperor inadrillchuckiftheyhaveaparallelshankA

drillchuckismountedonaMorsetapershankthatisusuallythelargestMorsetaperthatthetailstockwilltakeThelargestsizeof drill that will normally fit a drill chuck is frac12in (13mm) indiameter although larger chucks are available at a cost Thesmallest sizeofdrill thatafrac12in (13mm)drill chuckwill take isusually about 116in (15mm) This is because the larger drillchuck is incapableofclosingdownenoughto take thesmallersizesofdrillThismeanswewillprobablyneedtwodrillchucksoneforlargerdrillsandoneforsmallerdrills

Hand-tighteningdrillchuck

TherearetwomaintypesofdrillchuckOneistightenedbyusinga chuckkeywhichhasa small bevelgearbuilt on to itthatmates with the outer sleeve of the drill chuck itself Theother type is hand tightenedwhere the outer chuck sleeve isknurledtotightenthedrillthesleeveisturnedbyhandLargerdrillsabovefrac12in(13mm)usuallyhaveaNo1orNo2

MorsetapershankYoucangetMorsetapersleevestoconvertalargeMorsetoasmallerMorsetaperYoucanalsogetasmallMorsetolargeMorsetaperconverteraswell

Drillwithataperedshank

Some larger drills are also available with parallel shanksTheyaremadewithasteppeddownfrac12inparallelshankandarecalledblacksmithrsquosdrills

Blacksmithrsquosdrill

Themostusefuldrills in theworkshopcomeassetsofhighspeedsteeljobberdrillsinacaseThemostpopularsetcovers1mmto6mm increasingby01mmstepsAnotheruseful setcoversfrom6mmto10mmalsoincreasingby01mmstepsIfyouareintomodelengineeringasetofnumberdrillsfromNo1toNo60istoberecommended

Asetofmetricdrillscovering1ndash6mm

Drills are also available in different lengths Stub drills areshorter than standard jobber drills Several lengths of longseries drills are also available ranging from one and a halftimesthelengthofajobberdrilluptoseveraltimesthelength

Differentlengthsofdrills

Mostdrillshavetwoflutesbutcoredrillsarealsotobehadwith three four or evenmore flutes As their name suggeststhese are usually used for drilling out cored holes in castings

CoredrillsarenotnormallycapableofstartinganewholebutareusedforopeningupexistingholesAstandarddrillusuallyhasanincludedangleof118degrees

Stub drills and cobalt drills often have a 135 to 140 degreeangle for use on hardermaterials such as stainless steel andaircraftsteelsBack rakeondrills is oftenground radially Another typeof

pointhoweverhasfourfacetstothepointFour-facetdrillsaremuch better at starting a hole than a standard jobber drillwhich tends towanderunless followingacentrepoporcentredrill Four-facet drills also require less pressure to drill a holesincethepointisthinnerthanastandarddrillandtheyarefareasier to sharpen accurately by hand than standard jobberdrillsDormerdoarangeoffour-facetdrillscalledA002withatitaniumnitridecoating(TiN)andafour-facetpoint

Three-flutecoredrill

DormerA002four-facetdrillpoint

To drill an accurate sized hole requires two ormore stepsfirst youdrill the hole undersize (by perhapsfrac12mm) then youfollowthroughwithasizedrillThechancesaretheseconddrillwillcutdeadtosizeasitisonlycuttingasmallamountfromthediameter Obviously if you are drilling a large hole moreintermediatestepsmayberequiredSpeedsfordrillingarethesameasthosegivenforturninginthetableinChapter3

Setofcentredrills

REAMERS

There are several types of reamers available for use inworkshops again with either Morse taper or parallel shanksSomehavesizeparallelshankstheshankbeingthesamesizeas the reamer while others are availablewith shanks smallerthanthereamedsizeThereisalsothewaistedreamerwheretheshankisthesamesizeasthereamerthemiddleissmaller(waisted)andthecuttingendistheholesizeYoucanalsogetadjustablereamerswheretheendisexpandedbytheuseofascrewinthecuttingendofthereamer

Handreamerthefrontparthasaslighttaper

Straightshankmachinereamer

Waistedshankmachinereamer

Morsetapershankmachinereamer

Parallelreamersaredividedintotwotypesparallelmachinereamerswhere thecuttingdiameter is thesameallalong theream and hand reamers where the cutting end is slightlysmallerandtapersuptothefulldiameterWhen drilling a hole for reaming it is advisable to use the

two-holemethodfordrillingYouaremore likelytogetagoodsize hole prior to reaming For small reamers up to 04in(10mm) leave about 0012in (03mm) for the reamer toremoveForreamersuptofrac34in(19mm)leave0016in(04mm)and over frac12in (13mm) leave 0020in (05mm) For reamingspeedsuseabouta third toahalfof thedrillingspeed for thesamediameterFeedsshouldbefrom0002to0004in(0025ndash005mm)per toothper revMultiply the feedper toothby thenumberofteethtogivethefeedperrevolutionItisbesttouseneatcuttingoilformostmaterialsexceptfor

aluminiumforwhichparaffinshouldbeusedandplasticwhichrequirescompressedairorplainwaterYoushouldnotuseoilasacuttinglubricantforanytypeofplasticasitcanattackandordegradetheplastic

10BoringToolsandBoringHeads

Thischaptershowsyouhowtoboreholesinthelathewiththeworkheldinachuckmountedonthefaceplateorfixedtothelathecrossslide

TypicalHSSboringbar

DIFFERENTTYPESOFBORINGBARS

BoringaholetosizeisoneofthemostexactingjobsyoucandoinalatheItisrelativelyeasytoturnashafttofitaholebutitis much harder to bore an accurate hole to fit a shaft Ifpossibleyoushouldboretheholebeforeturningtheshaft

YouarelikelytocomeacrossHSSboringbarsorinsertedtipboringbarsBothhavetheirusesTheHSStoolisidealformostgeneralhole-boringjobsbuttheinsertedtiptoolisfarsuperiorfor materials such as cast iron The boring bar should be aslargeasyoucangetintotheholewhilestillallowingswarftoberemovedTheboringbarshouldonlyprotrudefarenoughtoenableitto

go completely through the bore Any more protrusion than isnecessarymay result in chatter or a dig in in the bore Thefront clearance on the boring bar tip should be as small aspossiblewithoutrubbingasstrengthisimportantBoringcanbeusedtofinishaholetosizeorsimplytotruea

holeupafterdrillingandpriortoreaming It isbesttoruntheboringtoolthroughtheholeusingafinefeedtothecarriageifyouhave the feedoptiononyour latheThe final finishingcutshouldbeputthroughtwoorthreetimesatthesamesettingtoeliminateanyspringinthetoolworkorlatheIftheholehasanintermittentcutthroughitsuchasacrossholetheholeisbestboredtosizeIt ispossible toborequite smallholes if youhave the right

tool Commercial lsquosmall holersquo boring tools are very expensivebut Ibuythemsecond-handwhenever Iseethemso Iusuallyhave a stock It is easy if time consuming to grind up smallboringbarsbuttheyareveryusefulespeciallywhenyouneedtotrueupasmallholepriortotappingorreamingEndmillsandslotdrillsmakeusefulboringtoolsAs longas

yougetthecuttingedgeoncentreheighttheywillboreaswellasaproperboringbarespeciallyinaluminiumYoucanmakesimplehome-madeboringtoolsbydrillingand

reamingaholetotakeaHSStoolbitintoasteelshankIdeallythe shank should be made of high tensile material or silversteelThetoolbitshouldbesecuredwithahightensilesocket-headedgrub screwor similar The tool bit caneitherprotrudefromthesideoftheboringbarforthroughholesorprotrudeatthe frontof theshankat45degrees ifyouareboringablindholeRoundboringbarscaneitherbeclampedintotheVeegroove

foundinsometoolholdersorheldinasplitsquareshankEithermethodissuitableespeciallyastheshankcanbeslidinoroutofthetoolholdertominimizeprotrusionSpeciallyshapedtoolbitscanbeusedtoundercuttheendof

the borewhen it needs to be screwcut and canrsquot be cut rightthrough Inserted HSS boring bars can also be ground up forundercuttingbeforescrewcuttingThereareseveralmethodsofcheckingaboreforaccuracyIf

youhavetoboretheholetofitanexistingcomponentperhapsaballraceyoucanuse theexistingcomponentasagaugeorturnupagaugeRoughout theborewithina few thouof thefinishedsize taking twoor threespringcutsUsea telescopicgaugeapairofcalliperswithamicrometeroradigitalverniertomeasuretheholeBorethestartoftheholebynomorethanonethouata timedonotgoright throughtheboreTest thefrontoftheboreifthegaugedoesnotgointotheborerunthetool right throughunderpower feedBoreout the frontof theholebyanotherthouchecktheboreandrepeatuntilthegaugejustgoesintothestartoftheholeFinishtheboreatthesamesetting checking that the gauge just enters Take a couple ofspringcutstoensuretheboreisparallelYoushouldnowhaveanaccuratelysizedholeThe trick to boring is to finish with very fine cuts Many

engineersdonotrecommendfinecutsbutIhaveneverhadaproblemaslongasthetoolissharp

Asetoftelescopicgaugesforcheckingaboreusedinconjunctionwithamicrometer

Checkingaborewithahome-madegaugeTheleadinisonethousmallerthantheborerequired

USINGABORINGHEADINTHELATHE

AnothermethodofboringacomponentinthelatheistoboltitdowntothecrossslideWhentheworkpieceisbolteddownandtheholeposition is linedupwith theheadstock youcanboretheholeintheworkpieceinseveralwaysFirst however you might need to put a hole into the

workpiece to clear the centre of the hole out of theway Youcandothisbyusingadrillinathree-orfour-jawchuck(smallerdrillscouldbeusedinadrillchuck)Startwithasmalldrillandworkupalmosttothefinishedsizeoftheholetobebored

Boringaholereadyforreaming

Toboretheholethefirstoptionistoholdaboringbarinthethree-jaw chuck This is a good basic method of boring aworkpieceonthecrossslideTheonlyawkwardbitisadjustingtheboringbarsothatasizeholeisboredThisisusuallydonebyanadjustingscrewpressingontothebackofthetipoppositethe cutting edge The tip itself is usually clamped by a grubscrewthroughthesideoftheboringbarHoweveryoucanuseaboringbarthatisafewthouundertherequiredsizeandfinishoffwithareamerA similar way that is easier to adjust is to use the same

boringbar in the independent four-jawchuckThen insteadofadjusting the tip in the boring bar you can adjust the entireboringbar inthefour-jawchuckThisasyoucanimaginewillbealoteasierthantryingtoadjustthetipintheboringbarThethirdmethodofboringworkonthecrossslideistousea

properboringheadThis iseasy toadjustas it isdesigned forthisverypurposeFinallyyoucouldusea lsquobetweencentresrsquoboringbarwhich

isheldbetweentheheadstockandtailstockcentresThisistheonly option when you are doing a long bore such as a largecylindercastingforalocomotiveortractionengine

Boringtheholeusingthefour-jawchuckmethod

Usingtheboringheadinthelathemandrel

Unlike when you are facing and boring a component in achuck you will not be able to face across the front of thecomponent (Boring heads with the ability to face across theworkareavailablebutareunlikelytobefoundintheamateurrsquosworkshop) Thismeans you will have to face across the workwith a flycutter in order to keep the face true with the boreFlycutters are available quite cheaply or you couldmake yourownandholditinthefour-jawchuck

Aflycuttersuitableforfacingthefrontofacomponentthathaspreviouslybeenboredonthe

crossslide

11KnurlingRadiusTurningandProductionMethods

This chapter explains how to use knurling tools and radiusturningtoolsaswellasusingbasicproductionmethods

KNURLING

Knurlingistheprocessofformingorimpressingapatternonapiece of metal often for the purpose of making a grip for apieceofequipmentsuchasaknobBothstraightanddiamondknurlscanbeproduceddependingonthetypeofknurlyouareusing Diamond knurling is usually done with two knurlingwheelsalthoughsingle-wheeldiamondknurlsareavailableKnurls are also available in fine medium and coarse sizes

although the size is relative fromdifferentmakers The speedfor knurling is usually about half of the turning speed for thesame diameter bar Normal knurling is of the male patternwheretheknurlingconsistsofraisedpyramidsFemaleknurlingismuchrarerandconsistsofdepressedpyramidsThere are threemain types of knurling tool but only two of

these are found in the average workshop The first type ofknurling tool is the so-called lsquocutrsquo knurling toolwhichactuallycutsaknurlratherthanpressestheknurlintotheworkThisisaspecialized tool more often used in industry and is veryexpensivesoitisnotfoundinmanyhomeworkshops

lsquoBumprsquoKnurling

The most common knurl is the single-or double-wheel knurlsometimes called a lsquobumprsquo knurling tool The wheels aremountedat the frontof the tool This typeof knurl is pressedintotheworkbyusingthecrossslideandcanproduceagoodqualityknurlHowever itdoesputveryheavypressureonthemandrelandlathebearings

Acommerciallyavailablestraddleknurlingtool

StraddleKnurling

Thebest typeofknurl foroccasionaluse is thestraddleknurlwhich has two knurling wheels that completely straddle theworkpieceThistypeofknurldoesnotputastrainonthelathebearings and so is preferred bymost lathe users (Two-wheelknurlingtoolsareavailablethatresemblestraddleknurlingtoolsbut they donrsquot open up to take anything more than smalldiameters relying on pressure at the side of the job like alsquobumprsquoknurl)To set the straddle knurl up wind the tool against a bit of

plateheldontothesideofthebarRemovetheplateandmovethetoolinbythethicknessoftheplatehalftheknurldiameterandhalfthebardiameterThiswillputthetoolontothecentrelineofthebar

Settingtheknurlingtool

In use set the knurling wheels to the centre as describedabove wind the knurls onto the outside diameter of the barwindtheknurlawayfromthebarandmovetheknurlingwheelsclosertogetherbytwicethedepthoftheknurlpatternSwitchthelatheonandwindthetoolbackontothecentrelineandthetool should start to form the knurl You can now traverse theknurlingtoolalongtheworkpieceto formtheknurl remembertousecuttingoilNote that theknurlsshouldhavechamferedsidesifyouaretraversingalongtheworkpieceYouneedtogodeepenoughsotheknurlisfullyformedbut

notsodeepastodeformtheknurlBecausetheknurlstraddlestheworktheknurlsstartoff independentlyandmaynotbe inalignment around the diameter Once you start moving theknurlingtoolbackwardsandforwardsalongtheworkhoweverthetoolshouldlineitselfupThismeansyoumayhavetoturndownorpartoffthebarwhereyoustartedtheknurlIfyougotoodeepespeciallyinaluminiumthewholedepth

ofknurlcouldgetdestroyedandevendropoff theparentbarThis is called flakingKnurling isnotadifficultprocessa littlepracticewillsoonhaveyouknurlinglikeaprofessionalengineer

Anaccomplishedbitofknurling

AformtoolcuttingaballTheinsetviewshowstheformtoolandafinishedball

RADIUSTURNING

Sometimesweneedtoformanexternalradiusontheendofabit of bar perhaps for a ball-shaped handle We can use asimple lathe attachment to do this Basically the attachment

consists of a short turning tool mounted onto a U-shapedcomponent that is arranged to pivot on another U-shapedcomponentheldinthelathetoolpostBy pivoting the attachment back and forth a radiuswill be

generatedForatrueradiusthepivotpointshouldbesetonthecentrelineofthebarTheradiusgeneratedwilldependonhowfarthetoolbitissetbackfromthecentrelineoftheworkpieceTosetthetoolupwindtheattachmentuptoaplateheldto

the sideof thebar youareworkingon remove theplate andwindinthewidthoftheplatehalfthewidthofthebarandthewidthofthefixturetothecentrelineofthepinThiswillputthepivotonthecentrelineThenyoucansetthetooltotheoutsidediameterofthebarThiswillproduceaballthesamediameterasthebarTo turnan internaldiameteruse the samemethodbut the

turning tool will need to pass through the centre of the pivotand out the other side You will be limited to shallowdepressionsratherthanlargesemicirclesbutthistechniquecanstillbeusefulonoccasionThealternativemethodof formingaball iswithaball form

tool

Astopbarblockforthecarriagestop

PRODUCTIONMETHODS

PRODUCTIONMETHODS

Foreaseofproductionthefirstthingyouneedtouseisabedstop (see Chapter 5) The chances are that you will need tomakeyourownTheoneIuseisveryversatileandconsistsofablockmountedatthefrontofthelatheheadstocktogetherwitharodtoactasthestopDependinguponwhatyouaredoingitmaybeusefultohave

morethanonestopbareachwithitsownseparatestopblockInusethebarisinsertedintothemainblockasfarasthestopblock(if fitted)andlockedinplaceThefirststopbarcouldbeusedto facetheworkpieceandthesecond(shorterbar)couldbe used to turn along the diameter while a third bar couldpositionthepartingofftoolAnalternativeadditiontothestopbarcouldbeawasher(orwashers)ofknownthicknessplacingthewasher(orwashers)onthebarwillextendthestoppositionbythethicknessofthewashersusedAusefultipistostampanumberonthestopblockssothat

eachone isnumberedYoucouldalso stamp the thicknessonthewasherssoyoudonrsquothavetokeepmeasuringthemandjustpickthemupinthecorrectorderItsavesalittletimeandhelpsavoiderrorsThe whole point about using a stop is the consistency of

positionwhichistransferredtotheaccuracyofthecomponentit gives Once you have learnt to use a stop youwill wonderhowyoumanagedwithoutitEvenforone-offcomponentsitwillsaveyoutimeForatypicalone-offsteppedshaftsetthestopsotheturning

tooljustfacesthebarandfaceoffMove the top slide along for the length of the turned step

requiredTurnthestepYounowhaveastepontheendofthebarofaknownlengthNofiddlingnomeasuringndashyouknowitiscorrectUsing the bed stop offers a simple way of doing repeat

turning of lengths and diameters in the lathe Stops are notlimited to production methods they are very useful formachiningone-offsaswell

A single stop bar will serve for much of the work you aredoingbutsometimesyouneedmorethanonestopTheanswerhereistousemorethanonestopbarinconjunctionwithastopblockEachbarhasitsownstopblockthatcanbetightenedupThenyoucaninterchangethestopbarsandeachbarcanbesettotherequiredlengthbyusingavernierorruleYoujustsetthetwostopblockstothedifferencerequiredandlockthestopbarintheholderasnormalWhenyouneedmorethanoneofeachitemitisveryeasyto

save time in theworkshop once the lathe is set up you canmake several items in quick succession A typical example ofthis type of production is a simple spacer Set a facing andchamferingtoolinonetoolholderapartingofftoolinanothertoolholderandadrillinthetailstockchuckThefacingtoolandparting off tool are in fixed positions to each other so it is asimplematter of drilling thehole facingoffwithone tool andparting off with the other As long as the gap between thepartingofftoolandthefacingtoolremainsconstantthespacerswill remain at the samewidth each time youmachine one ofthemTheeasywaytosetthethicknessofthewasheristofaceoff

theendofthebarbringthepartingofftooluptothefinishedface and lock the cross slide Wind the parting off tool backslightly so you can move the bar forward in the chuckMeasuring with the vernier calliperrsquos depth rod from therighthandfaceofthepartingofftoolbringthebaroutslightlylonger than is needed for the washer thickness Using thetailstock chuck drill the hole using a centre drill for the firstwashertoensurethedrill runstrueNowsetthefacingtool inpositionfaceoffthewasherandpartofffromthebarMeasurethe washer and adjust the facing tool either way so that thethicknessof thewasher iscorrectPull thebar fromthechuckslightlyfurtherthanthefacingtoolsothateachwashercanbefaced to lengthYoucanmakeasmanywashersasyouneedall of the same thickness The same applies to nuts and anyothercomponentthatneedstobeasetlengthIfmakingboltsor screws theprinciple is thesamebutyou

willneed to turndown thediameter tobe threadedThis timethedifferencebetweenthepartingofftoolandtheturningtoolisthethicknessoftheheadInordertofacetolengthhoweverawasher of a known sizemust be inserted between the stopblockandthecrossslideThiswasherwillbethelengthoftheturneddownportionofthecomponentIfyouwanttomakeabatchofcomponentsbutdonrsquotwantto

keepmovingorchangingtoolsyoucanmachinethebatchonestepata timedoingoneoperationoneachcomponentbeforedoing the next operation on all the components Repeat thisuntil the complete batch ends up as completed componentsYou have the added advantage that the components willprobablyallbethesameshapeandsizesomethingthatisnotalwayspossiblewhenmachiningeachcomponentindividuallyTo make a batch of components such as washers to the

samethicknessisquitesimpleSetupapartingtooltopartoffthe components and set up a facing tool to face thecomponentsThedifferenceinpositionbetweenthefacingtooland the parting toolwill be the thickness of thewashers Youcanadjustthethicknessofthewasherbymovingthefacingtoolbackwardsor forwardswith the topslide toadjust it The rearpartingofftooldoesnotmoveotherthantopartoffthewasher

Makingwasherstothesamelengthusingfixedpositiontools

TAILSTOCKTURRET

AnotherusefulaccessoryisthetailstockturretThisisarotatingheadthatisusuallysetbackatanangleItfitsintothetailstockof the lathe and has multiple stations to take different toolsoftenitwilltakefourfiveorsixtoolsThebenefitofthisisthatitcanhaveabarendstopacentredrilladrillacountersinkatapandadieoranycombinationthereofallsetupreadytousein sequence The tools normally fit into holes bored into theturretToavoidtoolsstickingouttoofar it isbesttousestubdrillsinsertedintoroundbarsthatfitintotheturret

Anindexingturretthatfitsdirectlyintothetailstockofthelathe

YoucaneitherdrillandtaptheroundbarsoruseLoctite tosecure the drill in the round bar You can also buy roundadaptorswithaJacobschucktapermachinedontheendtotakechucksAnothermethodoffittingchucksistodrillandtaptheround bar to take chucks with threaded extensions ThesechuckscanoftenberetrievedfrombrokenBlackampDeckertypedrillsDieholderscanslideonapieceofroundrodintheturretFor

smaller diameter threads you can stop the die from rotatingusing your hand There is no need to reverse the lathe whenthreading just stop it and spin the die off by hand the samegoes for taps For larger taps and dies you can use a shorttommybartostoprotationbutmakesurethatthetommybarpositionisclosertotheworkthantheendofanyofthedrillsorthetommybarwillsnapthedrillsifyouletgoofitorifthetapordiejamsupYoucanalsomakeorbuyarunningcentretofitintotheturrettosaveremovingitwhenyouneedtousealathecentreOnlydothiswithsmallorlightworknotheavybarsorfor largecutsWhenused inconjunctionwithagoodbedstop

system a tailstock turret becomes a very versatile productionfacilityTheturretcanbemademoreversatilebyfittingalever-feed

tailstockattachmentoracapstan-style feedattachmenttothetailstockturretEitheroftheseattachmentswillmaketheturretveryfastinoperation

Anindexingturretsetupwithastopandacentredrill

Standardlever-feedtailstock

SECONDOPERATIONWORK

SECONDOPERATIONWORK

Sometimes it is necessary to do second operation work on apart-machinedcomponentUsually thiswillbeon theoppositeend to the one already turned There are two main ways ofholding theworkpiece in the correct position for furtherworkthechuckbackstopandsoftchuckjawsThechuckbackstopisquitesimpletomakeItconsistsofa

draw-incolletapieceofplainbarforthestopabitofthreadedbar a nut and a top hat collar The collet goes into the lathemandrelandisdrawninbythethreadedbarThethreadedbargoesthroughthemandrelandislockedinplacebythenutandthe tophatcollarat the left-handendThe tophatcollar is toprotecttheendofthemandrelThestopbarfitsthecolletandispositionedsothattheworkislocatedattherightdepthinthechuckThismeansthateachcomponentput intothechuckupagainstthebackstopwillalwaysbeheldinthesameposition

Capstan-stylelever-feedtailstock

Adraw-inbackstop

Softjawswithhexagonsadded

The secondmethod is to hold the component in soft jawswhich are bored out to hold the component (see Chapter 5)ThismeansthecomponentshouldrundeadtrueandeachonewillbeheldinthesamepositionreadytobemachinedSoft jaws tend to be used for larger components while the

backstop ismore likely tobeused forbarworkYoucanboltextension pieces to soft jaws to hold larger diameters orextensions can be machined to make a nest to take largercomponentsWhensoft jawsarewornoutandfaceddowntoo

lowforfurtheruseyoucanboltapieceofhexagonbartoeachjawtogivethemanewleaseoflifeIfyouhaveabatchofthreadedcomponentstofinishonthe

second end you can screw them into a bit of bar held in thechuck If theyarehexagonbolts just tightenup lightlywithaspanneriftheyareroundheadandtheheadwillbemachinedlateryoucouldtightenanduntightenthemwithapairofpliersThe more production work you do the more varied the

methods you will learn and the quicker you will makecomponentstoahighstandardofaccuracyA sensitive drilling attachment can be very useful when

drillingwith tiny drills The feed is by hand which gives it itssensitivity The attachment can also be used for small tapswherethetravelisfairlyshort

Machiningscrewheadsbyholdingthescrewinathreadedmandrel

Asensitivedrillingattachmentthatfitsintothe

tailstockchuck

ThisVeeattachmentisusedforcrossdrillingandcanbeusedintheheadstockorthetailstockofthelathedependingonthelengthofthebartobecrossdrilled

ThisisarevolvingtaperforthetailstockIfyoufitadrillchucktoityoucanuseitasarunningsupportforsmallbarwhereacentreisnotpermissible

12TapsDiesandScrewcutting

Thischaptershowshowtousetapsanddiestocutinternalandexternal threads in the lathe Italsoexplainshowyoucansetupasimplegeartrainandcutascrewthreadwiththehelpofascrewcuttingdialindicator

Atypicaldie

CUTTINGTHREADS

Threadcuttingeither internalorexternal isan importantpartoflearningtousealatheThepurposeofathreadisusuallysothatyouareabletoholdpartstogetheralthoughotherusesforthreadssuchasleadscrewsandfeedscrewsformachinetoolsareoftencalledfor

Safetyhasalreadybeencoveredindepth(seeChapter2)butafewextrawordsonsafetywhenthreadcuttingarecalledforWhen tapping a hole or threading a bar from the tailstock atailstocktapordieholderisoftenusedForthesmallerthreadstheholdershaveaknurledbodyandrotationcanbestoppedbysimplyholdingthebodyoftheholderinyourhandAslongasyoukeepyourhandawayfromthechuckandany

sharp lathe tools on the cross slide you should be fine (ifpossible remove either the tool holder or the tool itself )Providedthereisnothingtocatchorsquashyourhandonyoucan hold the knurled tap or die holder in your handwhile thelathe is running slowly under power and releasing the holderwhen the full length of the thread is cut or the pressurebecomes too great for you to stop the rotation (By slowly Imeaninveryslowbackgear)For largerthreadshoweveratommybarwilloftenneedto

beusedtostopthetapordieholderfromrotatingWhenusingthe tommy bar to prevent rotation do not under anycircumstances use the lathe under power Instead switch themachinerightoffandunplugit ifpossibleTurnthetapordieholdingthetommybarwiththerighthandandstopthechuckfromrotatingwiththelefthandThere are already many published charts providing thread

data covering such factors as tapping hole sizes minimummaximum and effective diameters as well as pitches andthreadsperinchIwillnotbeprovidingthemherebutwishtopoint out that tapping size drills can vary with the materialbeingcutWhenIamtappingsmallsizes instainlesssteel forexampleIusuallydrillthehole0004in(01mm)largerthanthefigurestated in thechartThisway Iam less likely tobreakatapinthehole

HSSorCarbonSteel

TapsanddiesareusuallymadefromcarbonsteelorHSSHSStapsanddiestendtoremainsharpformuchlongerthancarbonsteeltapsbutcarbonsteelisusuallycheaperNewcarbonsteel

tapsanddieswillprobablybefineforsmallerholesandsoftermaterials but wherever possible HSS should be your firstchoice Second-hand taps and dies are sometimes availablefromtoolshopsoroneBaybutinmyexperiencetheyareoftenbluntandnotworthbotheringwith

Lubricants

Whether tapping threading with a die or screwcutting it isnormallyessentialtousealubricantevenonbrassForbrassaluminium and bronze kerosene (paraffin) or white spirit isgenerallyusedandcanwithadvantagehaveasmallamountofcuttingoiladdedFor steel and stainless steel amodernpaste-based tapping

compound or cutting oil should be used This can also beappliedtocopperthismetalcanbestickybuttakeiteasyandall should gowell I also use paste or cutting oil on cast ironAlthoughmostrecommendationsaretocutcastirondryIhavefoundalubricanttobeveryhelpful

Screwthreadpitchgauge

ThreadGauges

When following a published design you will probably use thethread sizes as recommended by the designer If you are

making a thread to match an existing thread however youneedtofigureoutwhattheexistingthreadisThisiseasiesttodoonanexternalthreadIfyouhaveonlythenuttrytofindaboltthatwillfititandusethattocheckthethreadIfyoucanrsquotfindamatchingboltandtheholeinthenutisbigenoughyoucouldtrypressingabitofplasticineintotheinternalthreadandmeasuringthatTomeasuretheexternalthreadweneedtodeterminethree

thingsusingathreadpitchgauge theoutsidediameterof thethread the pitch of the thread and the thread angle Thesethree checks will probably be sufficient to decide what thethreadactuallyisBritish threads such as British Standard Fine and British

Standard Whitworth and also the Model Engineer threadsystemhaveanangleof55degreesAmerican threads such as UNF (Unified Fine) UNC (Unified

Coarse) UNEF (Unified Extra Fine) ANF (American NationalFine)ANC(AmericanNationalCoarse)are60degreesasisISOmetricUnusually theBritishStandardCycle thread is also60degreesThe other thread youmight come across is the BA (British

Association)threadThishasathreadangleof47frac12degreesandismetricbasedThelargestBAthreadis0BAwhichhasa6mmdiameterwith a 1mmpitch TheBA series godown to 22BAbutinpracticeyouareunlikelytocomeacrossanythingsmallerthanabout14BA

TAPS

TappingistheprocessofcuttinganinternalthreadwithatapFirst a hole is centre drilled and drilled in the workpiece Irecommend that you give the top of the hole a 90-degreecountersinktogivealead-intothetapandalsotostopthetapfromthrowingupaburrontothefaceofthework

Setofhandtaps

TypesofTap

The many types of tap can be divided into hand taps andmachinetapsHandtapsarenormallyheldinatapwrenchbutcan be held in the lathersquos tailstock chuck or a purpose-madetailstocktapholder

Close-upofahandsecondtap

WhentappingbyhandstartthetapuntilitstartstobiteandgiveitanextraturnorsoReversethedirectionofthetapforaturn to break the chip Continue forward for a couple of turnsand then reverseasbeforeContinue todepthor through theworkpiece by continually tapping a couple of turns reversingandcontinuingforwardThisshouldclearthechipsandpreventthetapfrombreakingIfthetapgetshardtoturntakeitrightoutoftheholetoclearanyswarfaddsomemorelubricantandcontinuetappingA set of hand taps will normally comprise a taper tap a

secondtapandaplugtapUsuallyyouwillstartaholewithataper tap This is a tap where the outside of the thread isreducedtowardsthepointbygrindingitonataperThistypeoftap can be used to start the hole but if the hole goes rightthrough the work it may be possible to screw the tap rightthroughtheholesoformingafullthreadrightthroughIfthetapertapistooshortorifyouaretappingablindhole

youneedtofollowthetapertapwiththesecondtapwhichhasmuch lessofa taper In fact itonlytapersrightat thestartofthetapTheplugtapisfinallyusedusuallytofinishoffablindhole

Theplugtaphasnotaperonitjustashortlead-inontheendBetween the three you should be able to tap themajority ofholesintheworkshopWhentappingblindholesitisbesttoworkoutthedepthand

fromtherethenumberofturnsneededforthetaptoreachthebottomoftheholeAsanexamplesaytheholeis9mmdeeptothepointThe tapenters2mminto theholebeforestarting tocutSo9mmless2mmgives7mmThepitchofthetapis05mm7mmdividedby05equals14sothenumberofturnstothebottomoftheholeis14Inpractice12or13turnswillbethemaximumneededWhen tapping blind holes make sure that all swarf is

removedfromthebottomoftheholebeforestartingtotap

Selectionoftapholders

HoldingTaps

TherearetwomaintypesoftapwrenchthehandtapwrenchwhichisdesignedtobeheldwithbothhandsandtheTeetypetapwrenchwhichoncestartedcanoftenbeusedone-handedTapsusuallyhaveeitheracentreholedrilledintheshankor

theshankisgroundtoapointThismeanswecansupportthetapfromthetailstockeitherbyusingalathecentreorbyabitofbarinthetailstockchuckwithafemalecentreinitTeetypetapwrenchesoftenhaveafemalecentreintheendandcanbesupported on a running centreWhen the tap is supported bythe tailstock at one end and the hole in theworkpiece at the

otheritmustbeinlinewiththeholeintheworkpiece

Machinetap

MachineTaps

Themaintwotypesofmachinetaparethespiralpointandthespiral flute The spiral point pushes swarf downwards throughthe hole while the spiral flute pulls the swarf out of the holeSpiralflutetapsaremuchweakerthanspiralpointtapsandintheory should not be used for tapping by hand However inpractice you can often get away with hand tapping using aspiralpointtapifyouareverycarefulIneithercasethetapisdesigned for continuous rotation swarf being automaticallycleared so the regular reversal as with a hand tap is notnecessaryIf you are careful you can probably get away with using a

hand tap under power but only do this with a hand-held tapholderwhereyoucanquicklyletgoifthetapstartstostickYou can also getmachine taps thatwill cut a thread under

powerbyscrewingthroughthejobwithoutstopping

Spiralflutetap

SpeedsforTapping

Tappingspeedsshouldbe low lowbackgearspeedshouldbefineWhenyouhavetappedtheholetodepthorrightthroughtheworkpiecestopthelatheandspinthetapoutbyhandThiswillbequickerthanreversingthelathe

ThreadingfromtheTailstock

For small taps you can use the sensitive drilling attachment(seeChapter11)orifthetapislargeryoucoulduseaslidingtapholderThiscanbeassimpleasachuckmountedonataperat one endwith a parallel hole through the chuck shank ThechuckthenslidesonabarheldinthemaintailstockchuckForlargetapsyoucanuseatommybartostopthetapholderfromturningbutthetommybarshouldnotbesolongastofoulthelathebedoranyotherpartofthemachineifyouhavetoletgoInfactitisfarsaferifyoudonotusethetommybartothreadunderpower

DIES

Dies also come in carbon steel andHSS versions The outsidediameterofadieoftenvarieswiththesizeofthethreadbeingcutalthoughthediameterwillbetooneofasetstandardDiesusually have themakerrsquos name and the thread details on thefrontof thedieThis is theside that ispresented to theworkThediewill havea short lead-in if this isnot requiredon thefinishedthreadyoucanreversethedieanditwillcleanuptoashoulder

SlidingtapholderSlidingdieholdersarealsoavailable

When cutting a thread especially a small one it pays tomaketheinitiallengthofthreadlongerthanthatrequiredThisissoyouhaveabitat thefronttoplaywithtogetthethreadright Then you can part off the excess length leaving a goodthreadoftherequiredlengthDies are usually split so you can adjust them to cut a size

threadIdeallyyoushouldhaveadieholderforeachdiesoyoucansetthedietocutsizewithouthavingtoresetiteverytimeyouchangethedieThedieshouldbesetsothatitcutsasizethreadinonepassDie nuts are often hexagonal in shape They are used to

cleanupanexistingthreadthat isdamagednot tocutanewthreadfromscratchFor each thread you are going to cut you should make a

home-madegaugetappedwithyourowntapWhenyoucutthethreadanditfitsthisgaugeyoushouldthenhaveagoodbutnottightorloosethreadYoushoulduseatailstockdieholderwithaslidingbodywhen

threadingfromthetailstockasthiswillholdthedietruetothethreadIdeally the tailstock die holder should be knurled and also

haveatommybarholeforeaseofuseThe speed for threading with a die in the lathe should be

quitelowamaximumof60rpmshouldbefineformostjobs

SCREWCUTTINGATHREAD

Whilecuttingathreadwithtapsanddiesisperfectlyadequatefor most applications the ability to cut an accurate screwthreadbyusingthelatheisaveryusefulfacilitytohaveIfthethread is large or non-standard taps and dies may not beavailable or they may be so expensive as to be out of thequestionforuseintheamateurrsquosworkshopVariouspitchesofthreadcanbecutbythesimpleexpedient

of changing the configuration of the change gears or alteringtheleversonthescrewcuttinggearboxifoneisfittedWewillconcentrate on a lathe with change gears if you have ascrewcutting gearbox please refer to the manufacturerrsquoshandbookMost lathes that youwill comeacross are likely to have an

imperialpitch leadscrewThiswillbeapitchofsomany teethper inch (TPI) Typically this will be 4 or 8 TPI although otherpitchesareavailableForourexamplewewillbeusingalathewithan8TPI leadscrewandasetofchangewheelscomprisingthefollowingnumbersofteeth2times202530353840455055606570and75

SETTINGUPTHECHANGEGEARS

Letrsquostakeatypicalthreadpitchof20TPIForeveryturnofthemandrel the leadscrew needs to move forward 120in Thismeans we have to set the change gears so the mandrel toleadscrewturnratio iscorrect Inpracticethemandrelgear islikely tobe20 teethand this is unlikely to change nomatterwhat thread we are cutting This means we will change theleadscrew gear which has to have the correct ratio to themandrelTheTPIwewishtocutis20usingaleadscrewwithapitchof

8TPI20dividedby8givesusaratioof251Thismeansthatthe mandrel gear needs to rotate at 25 times the leadscrewgearAsthemandrelhas20teeththeleadscrewgearneedstobe25times20teethwhichisa50toothgearInpracticea20toothgearanda50toothgearmaybetoosmalltotransferthedrive from the mandrel to the leadscrew and intermediategear(s)willneedtobeusedThese gears are called idler gears and they can have any

number of teeth Youmay think these idler gears change theratio of the mandrel to the leadscrew but they do not Theysimply transfer the drive from the mandrel gear to theleadscrew and the ratio stays the same This concept can behardtograspsoIwilltrytoexplainitsimplySay the mandrel gear does one turn This makes the idler

gearorgearsmoveexactly20teethandthisinturnmovestheleadscrewgearexactly20teethAsyoucanseetheratiodoesnotaltertheleadscrewgearmoves20teethforevery20teeththemandrelgearmovesandtheratiostaysthesameThistypeofset-upisknownasasimplegeartrain

Simplegeartrain

Compoundgeartrain

Letuslookatanothercommonthreadpitch32TPITheratioofleadscrewtoTPIis41(8times4=32)Sotheleadscrewgearneeds to be themandrel gear 20 teeth times 4 = 80 teethLookingattheavailablegearswedonrsquothavean80toothgearThismeanswewillhavetouseadifferentmethodtogetour41ratioWithamandrelgearof20teethwecouldusea40toothto

give us a ratio of 21 We are now halfway there but needanotherpairofgearswitha21ratioWedohavea30anda60

toothgearsothiswouldgiveusoursecond21ratioWecouldnot set these gears up as in the previous example howeversince the two intermediate gears would just act as idlers andtheratiowouldbe2150percentoutfromwhatisrequiredWhatwewouldhavetodoismountthe40toothandthe30

tooth gears on the same spindle so they rotate at the samespeedaseachother(The20toothgearmustdrivethe40toothgearandthe30toothgearmustdrivethe60toothgearinthisorder)Thiswouldgiveusthecorrect41ratiothatweneedAswehavemountedtwogearsononespindlethisisknownasasinglecompoundgeartrainDependingonyourlatheyoumayneedanidlergearbetweenthe30toothgearandthe60toothgearAgainthiswillnotalterthegearratiosYou can also have double compoundgear trainswhere two

lots of gears are mounted together on two spindles This istaking us into complicated territory however and I will referreaders to the screwcutting chart provided for their particularlathe Ifyour lathedoesnotcomewithascrewcuttingchartasearchon the Internet should findone that you candownloadandprintoutThemost likely application of double compound gear trains

would be to cutmetric threads with an imperial leadscrew orimperialthreadsover60TPII have tried to keep this explanation of setting up

screwcutting gears simple and the maths to a minimum Theexplanationgiventogetherwiththescrewcuttingchartforyourlatheshouldbemorethansufficienttogetyougoing

ExternalscrewthreadtoolmadefromaCoventry

diechaser

CUTTINGTHETHREAD

The speed for screwcutting should be about mid-back gear ifyouhaveitpreferablysomewherearound30ndash40rpmatmostTherearetwomainmethodsofscrewcuttinginthelatheThe

firstoneinvolvesthetopslidesetparalleltotheworkandintheothermethodthetopslideissetonanangletothework

Externalsinglepointscrewthreadtoolsettinggauge

Cuttinga20TPIThreadwiththeTopSlideParallel

For a 20 TPI Whitworth thread the pitch is 0050in and thethreaddepthisaconstant064ofthepitchsothethreaddepthis 0050 times 064 = 0032in This is the depth the cross slideshouldbewoundinWhilethedepthofthreadis0032inyoualsoneedtomove

the top slide forwardat eachpass Fora standardVee threadthisneedstobehalfthein-feedofthescrewcuttingtoolsoyoumovethecrossslideinby0010inandmovethetopslidealongbyhalfthis0005in

Cuttingascrewthreadwiththetopslidesetparalleltothelathe

Cuttingascrewthreadwiththetopslidesetatanangletothelathe

Theendresulta20TPIfinishedthreadbeforetidyinguptheendandundercutting

Cuttinga20TPIThreadwiththeTopSlideatanAngle

This angle will vary according to the thread being cut but itshouldbeabout1degree less thanhalf the includedangleofthethreadforaWhitworththreadof55degreesforexampletheangleshouldbehalfof55degreesminus1degreegiving265degreesNotethattheangleistakenwiththetopslidesetat90degreestotheworkWiththetopslidehandlefacingyou(at90degreestohowit isnormallyused)rotatethetopslidethe required number of degrees (265) to the right Beginnersoften rotate the top slide 265 degrees to the left from thenormalpositionwhichwouldgivean included threadangleof127degreesThisisclearlywrongBecausethetopslideissetonanangleyouwillneedtofeed

thetopslideinfurtherthanifthetopslideissetparalleltothelatheYoucan findthe increaseddepthof threadbyusingthefollowingformula

c=bcosineofA

whereAistheanglecalculatedathalftheincludedthreadangleminus1degreegiving265degreesb is thedepthof thread(forWhitworththreadsthisis064timesthepitch)andcisthecalculatedangulardepthofthreadFor a 20 TPIWhitworth thread the pitch is 0050in and the

threaddepthisaconstant064ofthepitchsothethreaddepthis0050times064=0032inThecompensateddepthofthreadisthen0032individedbythecosineof265degrees=00357

UsingtheThreadCuttingIndicator

With an 8 TPI leadscrew if the thread being cut has an evennumber of threads the leadscrew can be engaged at anypositionof the threadcuttingdial indicator If the thread isanoddnumberyoushouldusethesamenumberoranyalternatenumberthatisoneorthreetwoorfourForthreadswithahalfpitch always use the same number For metric threads orpeculiar numbers do not disengage the clasp nuts withdrawthescrewcuttingtoolandreversethemotoruntilthetoolgoesback to the start If the thread is an exact multiple of theleadscrewtheclaspnutscanbeengagedatanypositionIfindoubtalwaysengageatthesamenumberoneIttakes

verylittletimetotraversetheextradistancerequiredFor leadscrews other than 8 TPI please refer to your lathe

manual

AcknowledgementsandUsefulContacts

I would like to thankMy TimeMedia Ltd (Publishers ofModelEngineer and Model Engineersrsquo Workshop) Ken Wilson TonyJeffreeandTranswavePowerCapacitorsLtdfortheuseoftheirphotographs

USEFULCONTACTS

UnitedKingdom

ArcEuroTradeLtd10ArchdaleStreetSystonLeicesterLE71NATelephone01162695693Fax01162605805EmailinformationarceurotradecoukhttpwwwarceurotradecoukSuppliersofmachinetoolsandaccessories

ChesterMachineToolsHawardenIndustrialParkHawardenChesterCH53PZTelephone01244531631EmailsaleschestermachinetoolscomhttpwwwchestermachinetoolscomSuppliersofmachinetoolsandaccessories

CowellsSmallMachineToolsLtdTendringRoadLittleBentleyColchesterEssexCO78SH

ThebasicMyfordmodeltheML7wasmanufacturedformanyyearsTensofthousandsarestilltobefoundingaragesfactoriesandhomeworkshopsaroundtheworldThisistheprototypeML7LatheasrebuiltbyMyfordLtd

ThelaterML7RandSuper7modelswerefittedwithaclutchasstandardThissaveswearandtearontheelectricalcomponentsandthemotorTheyalsohadmorespeedsLaterversionsoftheSuper7canbefoundwithapowercrossfeedTheillustrationshowstheprototypeSuper7latheagainithasbeenrebuilttofactorystandardsbyMyfordLtd

TheAtoZofalathe(A)Changewheelguard(B)Countershaftpulleyguard(C)Drivebeltguard(D)Countershaft(E)Belttensionlever(F)

Oiler(G)Motor(H)Tumblergearoperatinglever(I)Headstock(J)Backgearoperatinglever(K)Mandrelnose(L)Left-handleadscrewbearing(M)Leadscrew(N)Halfnutoperatinglever(O)Toolclamp(P)Topslide(Q)Crossslide(R)Saddle(S)Apron(T)Carriagehandwheel(U)Screwthreadindicator(V)Lathebed(W)Rack(X)Tailstock(Y)Tailstockhandwheel(Z)Right-handleadscrewbearing

AnearlyMyfordlatheAlthoughverybasicitcandoalotofusefulworkintheworkshopespeciallyiftimeisspentonmakingafewsimpleaccessories

This book will show you how to use the lathe safely andeffectively in your workshop but first you should ensure thatyou are familiar with the main parts of the lathe and theirterminologywhichmaybefoundonpage9Chapter1ofthisbookisaboutchoosingalathewhatsizeof

lathe to buy the different types available desirable featuresandwhetheryoushouldbuyneworsecond-handChapter 2 covers installing a lathe how to lubricate it and

maintain it in good condition and advice on general safety inyourworkshopwithparticularemphasisonhowtousea lathesafelyChapter3will lookatthematerials fromwhichcuttingtools

aremadeaswellastheirbasicshapeandgeometryThenwe

willlookatselectingsuitablespeedsandfeedsChapter 4 dealswith sharpening lathe tools andhow to set

themupinthelatheChapter 5 covers the different types of chucks how to use

themandsetworkupaccuratelyinthemChapter 6 teaches you basic turning between centres and

then introduces turning with the work mounted on the lathefaceplateChapter7isaboutholdingworkinacolletandhowyoucan

make and use several different types of mandrel forworkholdingChapter 8 explains how to turn a taper using the top slide

theuseoffixedandtravellingsteadiesandmakingaformtoolChapter9explainshowtousedrillsandreamersinthelathe

includinghowtoselectthecorrectspeedsandfeedsChapter 10 shows the different ways to bore holes in the

lathewiththeworkheldinachuckmountedonthefaceplateorheldonthecrossslideChapter 11 explains how to use knurling tools and radius

turning tools as well as making simple form tools and basicproductionmethodsChapter 12 shows you how to use taps and dies to cut

internalandexternal threads in the lathe Italsoexplainshowto set upa simplegear train and cut a screw threadwith thehelpofascrewcuttingdialindicator

1BuyingYourFirstLathe

WHATSIZEOFLATHEDOIREQUIRE

ThefirstthingtoconsiderwhenbuyingalatheisthesizeoftheworkthatyouwanttodoWhatisthelargestdiameteryouwillwanttoturnonitandwhatisthelongestlengthyouwillneedtoturnA3frac12times18in(90times457mm)lathewillallowamaximumdiameterof7in (178mm) tobe turnedover the lathebed thelatterfigureisknownastheswingInpracticethoughthisisatheoreticalmaximumas it is stillnecessary toholdandclampthe article being turned The swing over the cross slide isusuallymuchsmallertypically2in(50mm)Many lathes however aremanufacturedwith a gapbed at

the headstock end to enable short items of a large diametersuchaslocomotiveortractionenginewheelstobeturnedLathes are also sometimes available as standard and long

bed lathes The long bed lathe as the name suggests allowslongermaterial to be turned within the capacity of the latheWhen turning longermaterial the diameter will be limited bytheswingoverthecrossslideThiswillbealotsmallerthantheswingoverthebedIfbuildingamodelsuchasatractionengineoralocomotive

the deciding factor for the size of lathe is likely to be thediameterof the largestpairofwheels thatneed tobe turnedBefore deciding on the size of lathe required you shoulddetermine the size of the largest diameter and the longestlength of material that needs to be turned Another factor indeterminingwhat lathe tobuy is theavailabilityof sparesand

accessoriesisthecompanystilltradingwillitstillbetradinginthe future and are there large amounts of secondhand partsandaccessoriesavailablefromtooldealersoroneBay

Atypicalinvertertoconvert240voltssinglephaseto240volts3phase

LATHEELECTRICS

Single phase electric is where the lathe plugs into the mainssupplyinyourhouseThemotorwillhavetheusualliveneutraland earth leads Lathes supplied for factory use usually havethree phase motors and require three live wires each of adifferentphaseThinkofaphaseasan incomingwaveon theseashore three successive waves make up the three phasesneededEachphaseisthesameastheprecedingonebuttheyareoutofsyncandallpeakatadifferenttime

Aforwardreversecontrolboxforaninverter

Convertersandinverters

Youcan runsome3phasemotors fromasinglephasesupplyviaaconverteroraninverterThemotor informationplatewillusuallysay240volts440voltsif it iscapableofrunningonaninverter Inside the motor there will be changeover tags tochange the motor from 440V down to 240V Follow theconverterinverter manufacturerrsquos instructions for furtherinformation It isnotusuallyverycomplicatedto runa240V3phasemotor from an inverter and thiswill give a quieter andsmoother running motor than a single phase supply canprovide This usually requires some simple programmingexplainedintheinverterrsquosinstructionsanditusuallytakesfiveminutestogetthemotorworkingproperly

ThismotorispartoftheinverterpackageshowninthepreviousillustrationNowiringisinvolvedasthemotorleadplugsstraightintotheinverterbox

Theinverterrunsataconstantvoltagebutthespeedofthemotor will change as the frequency is raised or lowered Isuggest limitingyour inverter from full speed tohalf speed sothatthefanstillcoolsthemotorandstopsitfromoverheatingyoucanthenusethebeltstochangethemainspeedstepsasusual(Ifyoumustuseveryslowrunningitispossibletoaddaseparatefansuchasacomputercoolingfantogiveconstantairflow) Most inverter suppliers offer a forwardreverse andspeedcontrolboxthatcanbesetupinaconvenientpositiononthe machine These are well worth fitting for convenience inuse

Thisinverterisdesignedformountingonthefrontofthelathe

While inverters are designed to run only onemachine youcangetconverterstopowermorethanonemachineatatimeDependingonthesizeandpoweroutputconverterscostaboutthreetofourtimesasmuchasaninverterTherearetwomaintypesofconverterRotaryconvertersare

designedtorunmorethanonemotoratatimeThisis ideal ifyouwanttorunmorethanonemachineortwomotorsononemachineforexamplethemainmachinemotorandperhapsanauxiliary motor that drives the machinersquos coolant pump orpowerfeedsystem

Arotaryconvertercapableofpoweringmorethanone3phasemotor

ThesecondtypeisthestaticconverterwhichisdesignedtorunonemotoratatimeThereisofcoursenothingtostopyouusingthestaticconverteronmorethanonemachinebyfittingasuitablefemaleelectricalconnectortothestaticconverterandmatchingmaleconnectorstotheindividualmachinesThiswayyoucanconnectthestaticconvertertoonlyonemachineatatime

Thisstaticconverterissuitableforpoweringone3phasemotorIfyoufitasocketontheoutputhoweverdifferentindividualmachinescanbepluggedintoitoneatatime

Theelectricalloadingonrotaryorstaticconvertersmustnotexceed theirmaximumrating If indoubton the loadcapacityneeded to run your machine(s) you should consult the

manufacturerorsupplieroftheconverter

AnearthleakagetripisidealforquicklyeliminatingamotorwheretheelectricalinsulationisbreakingdownItisusefulfordetectingcertainelectricalearthingfaultsbutshouldnotbeusedasaguaranteeofelectricalsafety

Simpleelectricaltestingandsafety

Whenbuyingasmallsinglephasesecondhandlathetakewithyouanearth leakage testerof the typeused for lawnmowersandothergardentoolsIonceboughtaUnimat3lathetookithomeandpluggeditinItkeptblowingtheearthleakagetripinthefuseboxeventhoughithadworkedperfectlyatthesellerrsquoshouseIsolditonatalossbutthebuyerdidknowtherewasaproblemwiththeelectricsIt is most important that the metal parts of any lathe are

connectedtotheearthwirewhichisinturnconnectedtoearthMake sure that themotor frame is also connected toearthassome motors have dampening rubber mounts that insulatethem from themachine itself If in doubt about any aspect ofelectricalinstallationpleaseconsultaqualifiedelectrician

Acontinuousbedisidealwhenworkingwiththefaceplateorwithcollets

LATHEBED

Thelathebedisthebackboneoftheentirelatheandisthepartthat is mounted on the bench or stand There are two maintypesoflathebedtheplainbedandthegapbedTheplainbedisusuallycontinuousallthewayalongitslengthwhilethegapbedhasas itsnamesuggestsagap in thebedThis isnotaliteralgapbutasteppedsectionthatallowsbiggerdiameterstobeturnedthanyouwouldotherwisebeabletoturnonaplainbed latheThisgap isameansofmakinga lathesmaller thanwouldberequiredforaplainlatheabletoturnasimilarsizeof

componentSome continuous lathe beds have a section next to the

headstock that can be removed to increase the diameter thatcanbeturnedThisfeatureisusuallyonlyfittedtolargerlathessuchasaremostlyfoundinfactoriesSome lathes have hardened beds although most are just

plaincast ironTherearethreemaintypesofbedwayscalledshearstheplainflatbedwithsquarewaysabedwithaflattopand a 60 degree dovetail at each side and a bedwith raisedandinvertedVeewaysOnthelastofthesethetailstockusuallyrunsononesetofVeesand thecarriageonadifferent setofVees resulting in lesswear to themain slidesWidebedsarebetterandmoreaccurateasthelathecarriageislesslikelytotwistonawidebed

Close-upviewofatypicallathebedwithagapAgapbedlathehasalargerturningdiametercapacitythantheequivalentsizedcontinuousbedlathe

Someveryearly lathessuchas thosemadebyDrummondhad a round bed Although they worked well there is noadjustmentforwearinthelathebed

TheMyfordrangeoflatheshasasquareformofbed

ThistypeofbedhasaflattopwithaninvertedVeeateachsideTheVeesareusuallysetat60degreesbutcanvarywithdifferentmakers

The Unimat SL lathe was sold for many years and manysecondhandexamplesarestillavailableThismodeldiffersfrommostlathesinthatithastwosteelbarsasabedThisisnotaproblemhoweverastheUnimatisintendedonlyforverysmallandlightweightmodel-makingworkandthereistheadvantagethatthebedcanbereplacedbyfittingnewbarsWhen buying a secondhand lathe it is most important to

checktheconditionofthebedYouneedtomakesurethebedis reasonably free from dings rust and hacksaw marksHacksawmarksneartheheadstockareoftencausedbysawing

offworkwhile it isheld inthechuckdingsareusuallycausedbydroppingthechuckonthelathebedwhenscrewingitonoroffthemandrelAsimplechuckboardplacedonthebedwhilefittingorremovingthechuckwillprotectthebedItisalsoidealfor protecting the bed when filing or hacksawing work in thechuck

AlathebedwithraisedandinvertedVeesThecarriageusuallyslidesononesetofVeesandthetailstockslidesontheother

AmodernChineselathebedwithaninvertedraisedVeeThecarriageandtailstockusuallyslideonthesameVee

Wear ismost commonly found at the headstock end of thelathe as a result of machining many short components andrelatively few long ones Make sure the lathe carriage isproperlyadjustedattheheadstockandthenrunitalongasfaras you can towards the tailstock The carriage should bereasonablyfreebutnotlooseallthewayalongthebed

OldroundbedDrummondlathesarestillavailablesecondhandThisparticularexampleistreadledriven

AflatbedlathewithsquarebedwayssuchasaMyfordcanbe checked for wear on the lathe bed using amicrometer orvernierCheckovertheworkingpartofthelathebedonwhichthe carriage slides rather than the part that is not used forguidance Check both the width and the thickness of the bedwaysThetailstockshouldalsobeagoodslidingfitonanyguiding

surfaces Wear is most likely to be found on the tenon thatslidesbetween thebedwaysAworn tenoncouldprobablybereplacedbutthereisnotmuchyoucandoifthetenonguidesarewornTheonlyway to fixawornbed requiresacompletebedregrindThisislikelytobeexpensivesoitwouldbebettertolookforanunwornlatheDecentunwornlathesareouttheresincemanymodelengineersmayhaveboughtthemnewfortyorfiftyyearsagoandhardlyusedthem

TheUnimatSLisaverypopularsmalllatheItsbedconsistsoftwosteelbarsthatcanbereplacedveryeasilywithsilversteeliftheygetwornormorelikelywhentheygetrusty

Asimplewoodenchuckboardwillprotectthelathebedfromdingsandhacksawmarks

LATHEHEADSTOCK

Theheadstockisthelargecomponentmountedattheleft-handside of the lathe bed It needs to have good bearings An all-gearedheadwillalmostcertainlyhaveballorrollerraceswhilethe older type of lathe for amateurs may well have plainbearings either phosphor bronze or whitemetal These areperfectlyadequatebutyoushouldmakesurethere isnowearinthemSomelathesalsohaveamandrelthatrunsdirectly inbored holes in the cast iron headstock casting Plain bearingswillbeperfectlysatisfactoryas longasadequate lubrication isused

Close-upviewofaMyfordheadstockonanML7RNotethelargebronzebearingatthefrontTheearlierML7latheshadwhitemetalbearingsalthoughtheC7capstanhadbronzebearingsandahardenedlathespindle

Tocheck forwear in the lathersquosbearings fitachuck to themandrelandputadialtestindicatorontopofthechuckGentlytry levering the chuck up and down by using a steel bar orsimilarheldinthechuckYouarelookingforminimalmovementhereespeciallyonaheadstockfittedwithballraces

CheckingthelathebearingsforwearAnymovementupanddownindicateswearinthebearing

The mandrel is mounted in the headstock and is usuallythreaded to take a chuck or faceplate The lathersquos mandrelshould not move back and forth in the bearings If it doeshowever itwillprobablybepossibletoadjust ittocorrectanyendwise movement The mandrel should not be too stiff butshouldturneasilybyhandWhentestingalathemakesuretheheadstockbearingsare

correctlyadjustedsothatwherepossiblethereisnoplaySeta tool up take a trial cut alonga length of bar and check forchatter If you are using a correctly set tool and a suitablespeedchatterisasuresignofwornbearings

Manylatheshaveathree-orfour-stepdrivepulleyasthesecondstageofthedrivechain

POWERDRIVE

Manylatheshaveathree-orfour-steppulleyonthemandreltotake the drive from a similar pulley on the countershaft Thecountershaft is in turn driven from the motor which is oftenmounted at the back of the headstock and completes theintegral drive system that is so popular on most amateursrsquolathes

Thisparticularlathehasatwo-stepmotorpulleyandcountershaftwhichdoublestheavailablespeeds

SpeedchartonthebeltguardofaMyfordML7Rlathe

AfewlatheshaveaclutchfittedasstandardorasanoptionalextraTheclutchsaveshavingtostartandstopthemotorwhileitisrunningThishelpstostopwearandtearonthemotorandelectricalsystemAdifferenttypeofclutchsystemtheTriLevaspeedselector

wasonlyfittedtoMyfordML7orC7lathesThishasthreeleversfor setting threedifferent speedsDependingon the leveryoudepressyougetahighmediumorlowspeedIfyoupressoneof the levers downwhile another is right down the first leverwilldisengagethesecondsostoppingthemandrelfromgoinground If the lathe is switched off and all three handles aredepressed the mandrel is locked preventing rotation This isusefuliffilingorhacksawinginthelathe

TheclutchisnormallymountedinsidethelargecountershaftpulleyItisusuallyoperatedbyaleverattheright-handsideoftheheadstockattachedtoapushrodthatpassesrightthroughthecountershaft

TheMyfordTriLevaattachmentwillonlyfitML7andC7lathesandisnotsuitableforML7RorSuper7lathes

Therehasbeenatrend inrecentyearstodoawaywiththecountershaftandpulleysystemandtoreplacethemotorwithavariable speed one with an electronic controller This isacceptable except that at low revolutions it does not providethe torque that can be obtained from a countershaft systemThereisalsothedisadvantagethatthereisnowaytodrivethelatheifthecontrollercircuitboardfailswhereasyoucanjustfita new one if the belt breaks The board could of course befixed provided that a circuit diagram is available and theelectronic components can be identified Sometimes thecomponents are marked with internal house numbers ratherthan commercially recognized part numbers that can beorderedasareplacementfromacatalogueSomeboardsmighteven have the identification marks removed to make repairsalmostimpossible

ThethreadedendofalathemandrelisdesignedsothatthechuckbackplaterunstrueIfthechuckmountingfaceofthebackplateismachinedinsituthechuckshouldruntrueaswell

CHUCKMOUNTINGSYSTEMS

The threaded lathe mandrel nose is not by itself a suitablelocationforachuckorfaceplatesothenoseisusuallygivenaturned register on which to locate the chuck The chuck isscrewedrightontothemandrelovertheregisterandbuttsuptoaturnedcollartokeepthechuckrunningtrueTheothersideof the mandrel collar butts up against the main headstockbearingwhichusuallyactsasathrustfaceThemandrelisusuallyboredthroughandmachinedtotakea

MorsetapercentreforturningbetweencentresDonotputyourfingerineitherendofthemandreltocleanitwhilethelatheisrunningAneasywaytocleanthetaperintheheadstockiswithabottlebrush often sold in chemists to cleanbabiesrsquo bottlesAnalternativeisasoftfeltshotgunbrushdonotuseonemadefromwire

ThislathehasaplainregisterAccuracyreliesonthelathechuckbeingagoodfitontheregister

There are various systems of chuck mounting in useespeciallyon the larger lathesTheproblemwith thescrew-ontype with a register mentioned above is that the chuck orfaceplatecanunscrewwhenthelatheisrunninginreverseTheonly timeyoushould run this typeofmandrel in reverseveryslowly and without taking a cut is if you need to return thescrewcuttingtooltothestartofthethreadyouarecuttingAlternativespindlenosescanbeaplaindiscwitharegisterto

boltthechuckontooracamlockwherethechuckisheldontightlybyturningstudstolockthechuckontothemandrelTheplain discwith register relies on having chuckswith amatingregistertoworkproperly

AnAmericanstandardCamLockchuckmountingbackplateandCamLockchuckplatefittedtoachuckTheyareusuallyfittedtolargerindustriallathes

TheAmericanDstyleCamLocksystemeithertakesachuckor faceplate directly or it has a backplate that can have aregisterturnedonittosuittherequiredchuckAlthoughmanylathe mandrels with Cam Lock fittings have six holes thematchingchuckorfaceplateoftenhasonlythreelockingpinsThe advantage of both of the last two systems is that they

canberuninreversewithoutthechuckcomingoffthemandrel

Theleadscrewisdrivenfromthemandrelviaageartrain

SCREWCUTTINGGEARS

The left-hand end of the mandrel will often have a gearmountedonittodrivethechangewheelgearsandleadscrewThe mandrel gear usually drives a pair of gears called

tumblergearswhicharemountedona leveratthe leftoftheheadstock The direction of the leadscrew can be changed bybringingeitheroneortheotherintogearbyraisingorloweringaleverThereisusuallyacentralneutralpositionwhereneithergearisinmeshThissaveswearonthelathechangewheelsandleadscrew bearings as well as reducing noise while workingMandrelandtumblergearswillbediscussedfurtherinChapter12whenwesetupascrewcuttinggeartrain

A set of changewheels usually comprises about a dozengearsbutthiscanvarydependingonthemanufacturerThesechangewheels which take the drive from the tumbler gearsdown to the leadscrew are mounted on moveable studs toensurethegearsareinmeshwitheachotherDependingonthenumber of gears in the train the leadscrew will turn eitherclockwiseoranti-clockwiseThedirectionof the leadscrewcanbe reversed using the tumbler gears to enable right-hand orleft-handthreadstobecut

Oftentherearetumblergearsinthegeartrainthatcanreversethedirectionoftheleadscrew

YoucanusuallysetthegearstocutaveryfinepitchsothattheleadscrewactsasaselffeedwhenturningfromthesaddleIf you anticipate the need to do any screwcutting check thatthesuppliedscrewcuttinggearswilldotherangeofpitchesyourequire It has been known for certain lathes to be unable tohandle somecommonpitches a typical examplebeing26TPI(teeth per inch) A pitch of 26 TPI is often needed to repairmotorcycles and bikes made before the introduction ofmetrication

MakesurethatafullsetofchangegearsisincludedwiththelatheIfnottheyarereadilyavailablesecondhand

LEADSCREW

The leadscrew ismounted at the front of the lathe there areusuallybearings to support the leadscrewateitherendof thelathe bed It is used tomove the lathe saddle along the bedeither for a self acting feed or for screwcutting Some lathesalso have a graduated handwheel mounted at the right-handendoftheleadscrewforturningthemandrelbyhandSome of the larger lathes also have a separate feed shaft

whichisusuallyaplainroundshaftwithakeywaycutalongittodrivethesaddleusingafinefeedThissaveswearandtearontheleadscrewwhichisthenonlyusedforscrewcutting

Mostleadscrewscanhaveagraduatedhandwheelmountedontheright-handendoftheleadscrew

SCREWCUTTINGFACILITIES

Ausefulfeatureonanylatheistheabilitytocutscrewthreadsof different pitches Leadscrews come in different pitches acommon one being 8 TPI but many variations are fitted todifferent lathes including leadscrews with a metric pitch It isawkward tomachinemetricscrewswithan imperial leadscrewandviceversaSometimesmetricconversionsetsareavailablebuttheycanbehardtofindareusuallyexpensiveandrequirethe lathe to be changed over often using 127 tooth gearwheels This figure is derived from multiplying the metricequivalentof1in(254mm)byfivea127toothwheelisthusadirectconversiontoametricthreadonalathewithanimperialleadscrewA127 toothgear isusuallyvery large if itmatchesthepitchoftheremainingscrewcuttinggearsbutyoucouldusesmallergearswitha smallerDP (diametralpitch)but stillwith127 teeth Youwould also need amatching gear of say fiftyteethtogiveyoua2541ratio

Thislathehasbothaleadscrewforscrewcuttingandadriveshaftforthesaddleandcrossslidefeeds

Ascrewcuttingdialindicatorusuallymountedtotherightofthe carriage is a useful feature This is a small dial withdivisionsmarkedonitmountedonashaftTheotherendoftheshafthasagearthatmesheswiththeleadscrewandmakesthedial go roundWhen the clasp nuts are engaged the carriagemoves and as the gear moves at the same speed as thecarriagethedialstopsgoingroundWhen you engage the clasp nuts on the leadscrew the

positionwhereyouengagedependsonthepitchofthethreadbeing cut Some thread pitches allow you to engage at anydivision of the dial while others need to be engaged at aparticularpositionof thedialTheuseof thescrewcuttingdialindicator will be covered in Chapter 12 When using the finefeedyoucanengagetheclaspnutsatanymarkedpositiononthedialsoavoidingweartotheclaspnuts

AtypicalscrewthreaddialindicatorThisoneisengagedanddisengagedbylooseningtheboltandengagingthedrivegearwiththeleadscrew

LATHESADDLEANDAPRON

The saddle is thepart that slides on top of the lathebedandusually has the cross slide and top slide mounted on it Theapron ismounted to the frontof the saddleYoushouldmakesure there isnoplay in the saddle either sidewaysorupanddownandthatittravelsfreelyfromoneendofthelathebedtotheotherwithnotightspotsAtthefrontnearesttheoperatorthereisusuallyapairofclaspnuts(thesearesplitnuts)Thesecan be engaged or disengaged from the leadscrew forscrewcuttingormovingthesaddlealongwiththeleadscrewOncheaper lathes there is usually a solid nut that cannot bedisengaged

ThelathesaddleslidesalongthelathebedTheapronisboltedtothefrontofthesaddle

There is often a rack at the front of the lathe bed thatmatches upwith a handle and gears on the lathe apron Thiscan be used to move the carriage along the bed withoutwearingouttheleadscrewSomelatheshavethecarriagefeedwheel on the right but others have it on the left where hotswarfcanfallontoyourhandsThecheaperlatheshavenorackandrelyontheleadscrewtowindthecarriagebackandforth

ATee-slottedcrossslidemakesthesmalllathemoreversatile

CROSSSLIDE

On top of the carriage is the cross slidewhich canbewoundbackandforthacrossthelathebedWhenusingthecrossslideforfacingacrosstheworkthecarriageshouldbelockedtostopitmovingalongthebedLathesforamateurusearemorelikelytohaveaTee-slottedcrossslidewhilelargercommerciallathesare unlikely to have this facility The Tee-slotted cross slide isveryusefulespeciallyifyoudonrsquothaveamillingmachineYoucanboltworktothecrossslideformachiningusingacutterinthechuckorforboringworkpiecesthataretoolargetoswinginthechuckZero settingdials aredesirable for both the cross slide and

thetopslideTheyallowyoutosetthedialtozerowhichmakesiteasiertomeasuretheamountyouaretakingoffwithonecutInusewindthetooluptotheworkandtouchonsetthedialtozeroandwind the toolbackoff from theworkYounowknowwherezeroisonthetoolandcantaketherequireddepthofcut

withouthavingtoworkitout

Zerosettingdialsmaketurningandscrewcuttingtodepthveryeasy

Apairofzerosettingdialsreadytofit

LathescanbepurchasedwithimperialormetricfeedscrewsMostmodeldesignsareimperialbutmetricismakingheadwayandthismaywellbethewaytogoBewarelatheswithimperialfeedscrewsandmetricdialsTypically thesewillhavea funnynumber of handwheel divisions rather than a whole numberMostofthelathesyoumightcomeacrossareunlikelytohavea

power cross feed for facing This does notmatter as you caneasilywindthecrossslideacrossbyhandTheonlytimeIhavefound a power cross feed to be of use is when I had to faceacross a faceplate to true it up I have trued up similar sizefaceplatesbyhanditjusttookalittlelonger

Thetopslideismountedonthecrossslide

TOPSLIDE

ThetopslideismountedontopofthecrossslideThetopslideisnormallysetat90degreestothecrossslidealthoughitcanusually be swivelled around to various angles for turning ataperanangleorforscrewcuttingSomeofthecheaperlathesdonrsquothaveatopslideasstandardbutitisaveryusefulfeatureif you can get one The top slide should be able to rotateespecially for screwcutting but the top slide handlemay foulthecrossslideincertainpositionssocheckifthisisaproblemTheturningtoolisusuallymountedonthetopofthetopslideItcan either be clamped on directly usually with packing stripsunderneathorthetoolcanbemountedinatoolholdersuchasathree-orfour-waytoolpostoraquickchangetoolpostWewilllook at tool holding methods in Chapter 4 when discussingsettingupturningtools

TAILSTOCK

The component at the right-hand end of the lathe is thetailstock This usually has a handwheel to feed a drill into theworkbut leverfeedandcapstan-style feedingmechanismsarealso available You can lock the tailstock anywhere along thebed The tailstock has a barrel inside it that can bewound inandouttogivealinearmovementtodrillaholeinworkheldinthechuckThetailstockisusuallyboredtoaMorsetaperoftenof a similar size to the headstock so it can take accessoriessuchasdrillchucksmountedonaMorsetaperItcanalsotakeacentre for turningworkbetweencentres It is important thatboth the headstock and tailstock tapers are free frommarksscratchesandburrs

AlathetailstockwiththebarrelextendedNotethatitisnotusuallyaproblemifthechuckkeyisleftinthetailstockwhilenotinuse

Adjustment is usually provided between the base and themain body of the tailstock to allow for setting the tailstock inlinewith theheadstock Tailstocks canbe self ejectingwherethetool isextractedas it iswoundbackwhilesometailstockshavea throughholeandneeda tapwithabar to remove thetool Handwheel depth graduations for drill drilling to a

particularholedepthareveryusefulbutarenotoftenincludedon the cheaper lathes although industrial lathes usually havegraduatedtailstockhandwheelsThebettermakesoflathehavea lever clamping tailstock arrangement while the cheaperlathesoftenhaveaclampingspanneroranAllenscrewclamp

Allguardsshouldbefittedinplacebeforeoperatingthelathe

MACHINEGUARDS

Thedrivemotorcountershaft(iffitted)andpulleybeltsshouldallbeproperlyguarded It isveryeasy togetcaughtup inanunguardedmachineandtheconsequencescanbequitenastyThis has never happened to me but I have seen someonecaught up in a machine and it was not very nice I dorecommend that you make sure your machine guards arecorrectlyfitted

OTHERDESIRABLEFEATURES

Digitalreadoutsareusefulonalatheastheycanshowyouhowmuch to move the handwheels and how much material hasbeentakenoffTheyarequiteexpensivebutyoucan fit themyourself if youare carefulUnfortunatelymost of the cheaperversionsdislikesolubleoilorothercoolantifyougetitintothereadouthead

Adigitalreadoutsuitableformountingonalathe

Youwillneedtwoslidesoneforeachaxis

A soluble pump for cutting fluid is useful and often comesfittedasstandardonthelargerlathesHoweveratinofcuttingoilandabrushwillbegoodenoughformostworkandthatmaysuityoufine

Solubleoilpumpsandreservoirsarereadilyobtainable

Formostjobsyoucangetawaywithsomecuttingoilabowlandabrush

TheMyfordlsquoNortonrsquostylequickchangescrewcuttinggearbox

A Norton quickchange screwcutting gearbox saves time asyou donrsquot have to set up changewheel trains A gearboxhowever considerably increases the price of the averagesecondhand lathe A Myford Norton gearbox has twenty-fourpitchesandiscontrolledbytwoleversReversingtwogears inthe Myford changewheel train gives the gearbox twenty-fourfine feeds insteadof the twenty-fourscrewcuttingpitchesThegearboxhasa setofgearsarrangedasaconeBysliding thelever along and dropping themaster gear onto the cone youcanchangethegearboxratioandsothepitch

TheconegearsinsideatypicalNortonscrewcuttinggearbox(notanoriginalMyfordone)

SeveraldesignshavebeenpublishedtomakeyourownNortontypescrewcuttinggearboxThisoneisavailablefromHemingwayKits

SPINDLESPEEDS

Thespeed rangeneededona lathedependson thework it is

requiredtodoAgoodrangeofspindlespeedsisdesirablewithnoobviousgapsWithelectroniccontrolthisshouldnotbetoomuchofaproblemIdeally a back-geared lathe would be best but this means

either a good secondhand machine such as a Myford or aBoxford or alternatively one of the larger Asian-made latheswithanall-gearedheadstock

Thisbackgeararrangementisswitchedinandoutbyturningthetoggleonthepulleyandliftingaleveratthefrontofthelathe

Backgearnormallyconsistsoffourgearstwolargeonesandtwosmalloneswhichcanbeswitched inorout toreducethespeedofthelathebyaratioofusuallyabout51dependingonthe maker to enable you to turn large diameter workpiecesThis reduction is also essential on a screwcutting lathe asotherwisethemandrelwillbegoingtoofastwhilescrewcuttingandyouwonrsquotbeable tostop in the rightplaceat theendofthethreadIf buying a back-geared lathe check that both gearwheels

havealltheirteethItisamajorjobtostripdownalatheandfitnewgearwheelsassumingtheyareevenavailableassparesCheckthelatheinallgearrangeswiththelatherunningIfa

back-geared lathe or an all-geared head is noisy it could

indicatewearitwillalsobeanuisanceinyourworkshopasnoonewants to hear a noisymachine runningNoise could be amajorproblemespeciallyifyouhaveneighboursnearbyGearedheadsusuallyhaveawiderangeofspeedsthelarger

industrial lathescangoup tospeedsof2000rpmandsmallerversionsareoftenhigher

Anall-gearedheadonamodernindustrialsizelathe

On the more usual amateursrsquo lathe there is often acountershaft usually tensioned by a lever which tightens upthebeltreadyforuseThemiddlespeedofthecountershaft isusually chosen to be about one quarter of the motor speedMost small lathes have three speeds and the back geararrangement adds another three speeds giving six in all TheMyfordSuper7rangeoflatheshavefourspeedsandbackgearmaking eight speeds but there is also a double pulley on themotor countershaft section making sixteen speeds in allalthoughtheverylowestback-gearedspeedswillrarelyifeverbeusedSomeoftheolderColchesterChipmasterlatheshavewhatis

knownasaKoppVariatordriveThis isavariable speeddrivecontrolledbyadialandthesystemworkswellbuttheVariator

isveryhardtoreplaceifthedrivefails

ThissmallCowellslatheiscapableofdecentworkandatthetimeofwritingisprobablytheonlylathestillbeingmadeinBritain

MOUNTINGTHELATHE

There are three main options for mounting a lathe benchmounting portable or on a stand Ideally a makerrsquos standshouldbeusedformountingamediumto large latheandthestandisoftenanintegralpartof larger lathesAsmaller lathesuch as a Unimat or a Cowell can bemounted on a woodenchopping board or a similar small board These lathes can beputawayinacupboardafteruseThe alternative is a workbench but these are often made

from wood which can expand or contract depending on themoistureintheairWoodisnotagoodmaterialfromwhichtomakea stand for a larger latheas itwill attractmoisture andmayexpandshrinkordistortAmetalstandisabetteroptionWewilllookatinstallingthelatheinChapter2

AnArcEuroTradeC3screwcuttinglathemadebySiegThisisaverypopularentrylevellatheandmanyaccessoriesareavailable

Amedium-sizedscrewcuttinglathesuitableforgardenshedworkshops

SHOULDIBUYNEWORSECONDHAND

Beginnerssettingupaworkshopoftenaskifitisbettertobuyanew lathe or secondhand The preceding pages should have

given some guidance but there are more points to be takenintoconsideration

Alargerindustriallathewithafoot-operatedemergencycut-offswitchandbrake

BuyingNew

Thelistoflathesuppliersincludedatthebackofthisbookwereall in business at the time of writing Most will be willing todemonstratetheirrangeofmachinesattheirpremisesorwhileattendingmodelengineeringexhibitionsPaycloseattentiontomechanical noise the general paint finish and the workingslideway surfaceswhich should begroundDoes themachinehave sharpor roughedges (Handwheelsareespeciallypronetosharpedges)The main thing to consider though is the attitude of the

supplier Were they willing to talk to you and answer yourquestionseitheratanexhibitionoroverthephoneHowlongdo they take toanswer thephonewhenyou ring their servicedepartment Do they know the answer to a simple questionstraightawayordotheyhavetogetbacktoyouIsthemanual

written in English or Chinglish (translated awkwardly fromMandarinorCantonese)There are several suppliers of new lathes inmost countries

aroundtheworldbutthemajorityoflathesaremadeintheFarEastOftensupplierArsquosmachinescomefromthesamefactoryassupplierBrsquostheyarejustpaintedadifferentcolourandhavedifferentnamesandlabelsfittedAftersales service can vary greatly Usually companies that

havebeeninbusinesslongerwillofferbetteraftersalesservicebutotherpeoplersquosexperiencescanbefoundonInternetforumsoratlocalmodelengineeringclubsUsually theAsian lathesare reasonablywellmadebut they

often suffer from having plastic gears instead of metal onesOneortwocompaniessupplymetalgearsasstandardso it isworthaskingiftheirmachineshavemetalorplasticdrivegearsSome companies also offer after-market replacement metalgears

BuyingSecondhand

There aremany good quality secondhandmachines availablebut there is also a lot of worn-out rubbish If possible take aknowledgeable friend with you when purchasing a lathe Becareful when buying at online auctions such as eBay MostsellersaregenuinebutsomearenotNeverpartwiththecashuntil youhavechecked the latheover IhaveboughtoneBaywithoutproblemsbut Iamcarefulwhat IbuyandwhofromAsmall latheforacoupleofhundredpoundsisunlikelytobreakthe bank if it is a bit of a dog but a lathe that costs severalhundredpounds is adifferentmatter ThegreenMyfordML7RpicturedthroughoutthisbookwaspurchasedfromeBayItwasbrand new the motor had never been fitted and it was abargainwhencomparedwiththeretailpriceIdidpaycashoncollectionbutIwouldhavewalkedawayif ithadnotmatchedthedescriptioninanywayWhether purchasing new or secondhand check what

accessoriescomeaspartofthepackageandwhatwillneedto

bepurchasedseparatelyEssentialtoolingcanoftendoublethecost of a newmachine if it is not included in the price whilededicatedtoolingmaynotevenbeavailable forasecondhandbargainlathe

Youshouldnowhaveanideaofthesizeoflatheyouneedthefunctionofthedifferentpartsofthelatheandwhetheryouarebuying new or secondhand In Chapter 2 we will look atinstallingthelatheandsafetyintheworkshop

2InstallingtheLatheandUsingItSafely

If you are buying a new lathe completewith delivery to yourworkshopyoucangostraighttothesectiononsettingthelatheupIfyouarecollectingthelatheyourselfhoweveryoushouldpayattentiontoafewwordsonmovingit

Ifyouhaveroomtomanoeuvreanenginehoistcanbeusedtomovemachineryaroundsafely

MOVINGTHELATHE

MOVINGTHELATHE

When going to collect your lathemake sure someonewill betheretohelpyouloaditortakesomeonewithyouUnlessitisaminiaturelatheitwillbetooheavyforonepersontoliftHelpisalsoneededwhenyougetthelathehomeLiftingthelatheoutofacarcanbeharder than lifting it in It isadvisable tohavethreepeoplewhenunloading twoat theheavyheadstockendandoneliftingthelightertailstockendYoucanrentorbuyanenginehoist fora reasonablepriceand this canmakemovingthemachineeasierIf the machine is a substantial industrial type it would be

besttohireatransportcompanythatspecializes inmachineryremovals Professional machinery removers will usually haveproperlyequippedtransporttomoveheavymachinesThiswillprobablyworkoutcheaperthanattemptingtodoityourselfbutmake sure they have insurance in place in case they damagethelatheoryourpropertyYoushouldalsoensuretheyknowithas to beput in place as required in theworkshop youdonrsquotwanthalfatonofmachinerydumpedonyourdrivewithnowayofmovingitintopositionLathesareusuallytopheavywhenbeingmovedandcantip

overifyouarenotcarefulTheMyfordML7seriesforexampleoftenhasthemotorandcountershaftboltedtothebackofthelathe bed and this type of lathewill tend to tip backwards Asimple solution is to bolt two lengths of wood about 4 times 2in(100times50mm)tothelathefeetOneboltineachendwilldoifyou canrsquot drill holes in the correct position This will stop thelathe tipping backwards and also make it easier to lift IfpossibleyoushouldremovethetailstockThisisoftenaheavylumpofmetalbutitisusuallyveryeasytoslideitofftheendofthelathebedAnyotherlargeobjectsthatcanberemovedandreplacedlaterwillmakethelathelighterandeasiertomove

Twoplanksofwoodboltedtothelathefeetwilloftenturnanunmanageablemassofmetalintoaneasilyhandledmachine

Azerovoltsswitchisessentialequipmentonanymachinetool

Wearoldclotheswhenmovingyourlatheandhaveplentyofold rags to wipe off swarf and oil Lay down old blankets ordecoratorsrsquosheetsinsidethecarandasheetofthickcardboardMDForplywoodtohelpprotectthebootareawhenslidingthelatheintothecar

AsmallishlathecanoftenbefittedintoastandardhatchbackorestatecarYoumayfindhowever thatyouhavetodotwotrips one for the lathe and accessories and another for thecabinetthelathestandsonTosaveawastedjourneyIusuallytrytofitthelathecabinetinfirstIfIthenfindthatthecabinetdoesnrsquotfitIcanstillbringthelatheandtoolinghomeknowingthat Ihave tohireavan tocollect thecabinetbutalso that IhavenothadawastedjourneyIfyouhavetosplittheelectricsforexampletotakethelathe

offthecabinetdrawadiagramoftheelectricalconnectionssoyoucanrewirethelathewhenyougetithomeAdigitalcameraisalsoagoodmethodofrecordingthewiringconnectionsbutIwouldnotrelyonthecameraaloneIf the lathedoesnothaveazerovoltsswitch itwouldbea

good idea to fit one after you get the lathe home They areavailable quite cheaply andare easily fitted If in doubt aboutyourabilitytodoelectricalwiringconsultaqualifiedelectrician

Adjustablefeetareveryusefulforlevellingupthelathe

SETTINGUPTHELATHE

Somelathesusuallythelargerindustrialoneshaveanintegral

bedandcabinetThelathecanbesettotruewithjustshimmingunderthefeetorbyadjustingthefeetOther lathes may need to be mounted level and true to

ensureaccuracywhenturningSetthebenchstandas levelasyou can in both directions using a spirit level as a guide Anycheapspirit levelwilldoas longas it isaccurateYoucantesttheaccuracyofaspiritlevelbyturningitround180degreesifitisaccurateitshouldreadthesamebothwaysOnce the stand is reasonably level youcan level the lathe

ThisinvolvesjackingorshimmingupthelatheuntilitistrueinbothdirectionsIfusingawoodenbenchputmetalplatesunderthe feet tospread the loadShimoradjust the latheuntil it isreasonablylevel

Putthespiritlevelonthecabinetrsquoslongitudinalaxisandusetheadjustablefeettolevelthelathe

Insertalengthofbarinthechuckandputadialtestindicatoron top of the tailstock end of the bar Nip the headstock endmounting bolts down first and then tighten down the tailstockendboltsAdjustorshimthetailstockenduntilthereisnosignof movement on the test indicator Next 64repeat theprocedure with the dial test indicator on the front of the barAgainyouare looking fornomovementCheckbothdirectionsagainmakingsurethereisnomovementeitherhorizontallyorverticallywhenyoutightenthelathedownAdjustorshimuntil

there is no movement in either direction when the lathe isclampeddownAslongasthebedisnottwistedthelathebedshouldnowbetrue

1Insertapieceof⅛in(3mm)packingunderthespiritlevelatthetailstockendThiswillresultinarunonthedriptrayandalltheoldoilwillruntotheendofthelathemakingiteasiertocleanup

2Placethespiritlevelonthecabinetcrossaxisandusetheadjustablefeettolevelthelathe

3Putthespiritlevelonthelathecrossaxisattheheadstockendandlevelitasbestyoucan

4Putthespiritlevelonthelongitudinalaxisandlevelalongthelathe

5Testthetopofthebarthereshouldbenomovementwhenthelatheisclampeddown

6Testthefrontofthebaragainensuringthatthereisnomovementwhenthelatheisclampeddown

Alignthetailstockbyusingadialtestindicatorintheheadstock

AligningtheTailstock

NowweneedtosetthetailstockinlinewiththeheadstockDothisbyputting thedial test indicator into theheadstockchuckandtestthetailstockboreAdjustthetailstocktowardsthefrontortothebackofthebeduntilthetestindicatorreadstrueandtighten theclampscrewsA slightdifference inverticalheightwillnotbetheendoftheworlditjustmeansthereisprobablysomeweartothebaseofthetailstockcastingbutthereshouldbenovariationfromfronttobackinthehorizontalalignmentPutalongbarbetweenthecentresandtakealightcutalong

it using a fine power feed Run along the bar a couple moretimes at the same setting to remove any push offWhen youmeasure thebar it shouldmeasure the sameatbothends Ifthe bar is larger at the tailstock end you need to reduce theheightofthebedatthefrontofthetailstockslightlyIfsmalleratthetailstockendyouneedtoreducetheshimatthebackofthe tailstockend Itprobablywonrsquotneedmuchadjustmentasslightadjustmentstotheshimoradjustersatthetailstockendwillsoonbringitintoline

Usingatestbartocheckforparallelturning

LubricatingtheLathe

You should follow the manufacturerrsquos recommendations forlubrication Usually this is thin oil for the headstock oftenhydraulicoilandslidewayoil forthemovingpartsLubricationshouldbedoneregularlyIfthelatheisfittedwithasightfeedoileritshouldshowoilinitAdjustablesightfeedoilersasusedonMyfordandsimilarlathesshouldbeadjustedsothattheoildripswhen the lathe is running but does not dripmuchwhenthe lathe is stopped The slight vibration when the motor isrunningisusuallyenoughtocausetheoiltodripToomuchoilisbetterthannotenoughoilisfarcheaperthannewbearings

Atypicaldrip-feedlubricator

UseanoilgunonalltheoilnipplesYoucangetaroundthetendencyfortheoiltogoeverywhereexceptintothenipplebyputtingapieceofwritingpaperoverthenippleandthenusingthe oil gun as normal The paper will stop the oil squirtingeverywhereThemandrelbackgearalsoneedstobelubricatedWheninusethemainbackgearisrunningontheoutsideofthelathemandrelandneedstobelubricatedoftenoritwillgethotandwearChangewheels should be lubricated with oil not grease If

youusegreaseswarfwillsticktothechangewheelsandcauseunnecessarywearTo stopswarf running through themandrelanddroppingoutontothechangewheelsputawinebottlecorkor similar into the left-hand end of the mandrel This willeffectivelystopanyswarfgettingthroughtothechangewheelsOil the saddle and cross slide and also the nipples on the

tailstock Make sure oil is showing at the edge of the slidingsurfaces A squirt of oil on the cross slide and topslide feedscrew bearing is needed as well Check the manufacturerrsquosinstructions for lubricating the rest of the lathe Follow themotormakerrsquosrecommendationforlubricatingthemotorTrytoavoidusingWD40onthelatheWhileitisanexcellent

lubricantwaterdisplacerittendstodiscolourthelathebed

Useabitofpaperundertheoilguntostoptheoilsquirtingeverywhere

AvoidingtheRustFairy

Rust canplayhavocwith a lathe quickly turning thebedandother parts into a brownmess Various sizes of plastic coverssuitable forcovering lathesareoftensold foruseasbarbecuecoversinDIYstoresAplasticlathecoverwillhelptokeeprustatbaybutmoreneeds tobedoneAbagcontainingsilicagelplacedundertheplasticcoverforexamplewillabsorbexcessmoisturesilicagelcanbeboughtverycheaplyoneBay

SilicageliseasilyobtainablefromeBay

Alternatively you can buy a vapour phase inhibitor forprotecting the lathe The vapour phase inhibitor chemical issuppliedonafeltpadinsideaplasticpotThechemicalformsaprotectivelayeroneverysurfaceBecauseitisavapouritwillfind its way into every cranny and is also used for protectingtools and accessories in tool cabinets and drawers It usuallylasts for twelvemonths ifenclosedby theplasticcoverSomemachinetooldealersareabletosellsuppliesofthisproductinsmall ready to use containers rather than in industrialquantitiesAlwayscleanthelathedownafteruseswarfwillsoonrustif

leftonalatheasitwillprobablybecleanfromturningandwillnotbeprotectedbyoilTheuseofanovencookingtrayunderthe lathe bedmakes it easy to remove swarf at the end of aturning session The tray also helps to retrieve a parted offcomponentora lost screw froma tipped turning toolAnotheralternativeistocoverthelathechiptraywithnewspaperwhenyouhave finished turning remove thenewspaper screw it upandthrowitawayWhenfittingachuckorfaceplatetothelathemakesureyou

cleanthemandrelthreadtheregisterandthefaceYoushouldalso clean the mating threads the bore and the face on thechuckorfaceplateYoucancleanthethreadandboreeasilybyusing two toothbrushes bolted back to back with spacers inbetween Make sure the Morse tapers in the headstock andtailstock are cleanbefore fitting aMorse taper accessory TheMorse taper to be fitted should be free from scratches burrsandbruisesIt is good idea tomake a chuck board for usewhen fitting

chucks to a lathe or removing them This is a piece of wood(plywood will do) that sits on the lathe bed while you arescrewingthechuckonandoffThechuckboardwillprotectthelathe ifyoudrop thechuck It canalsobeused toprotect thelathebedwhenyouarehacksawingorfilinginthelatheIf you keep your lathe clean and lubricate it regularly it

shouldlastalifetime

AlargetraywillcatchmuchoftheswarfandtheholeslettheoildrainawayUsenewspapertosoakuptheexcessoil

SAFETYINTHEWORKSHOP

RememberyouareresponsibleforyourownsafetySafetyisamajorconcernintheworkshopTherearecertain

thingsyoushoulddoandobviouslythingsyoushouldnotByitsverynatureaworkshopcanbeadangerousplaceallwecandoismakeitassafeaspossiblewhilestillallowingustoworkinit

WorkingAlone

Mostofyoureadingthisbookwillprobablybeworkingaloneinasmallworkshopgarageorgardenshed IfyougethurtyoumaypossiblybeonyourownAsapriorityIsuggestyoutakeamobilephoneintotheworkshopandkeepitinyourpocketTheability to contact your family a friend or the emergencyservicesquicklycouldsaveyour lifeKeepthephoneswitchedoff while in the workshop however as it is an unnecessarydistraction

FirstAid

FirstAid

AFirstAidboxwithcontentsisanecessityandshouldincludeaneye-bathandeyewashYoushouldparticularlylearnhowtostopbloodflowingThereareplentyofwebsitesthatwilltellyouhowtodothisCheckthemoutnowbeforeyougobackintotheworkshop

ElectricalSafety

Checkforearthcontinuitywhilethemachineisunpluggedwithavoltohmmeterfromtheearthpinonthethreepinplugtothemetalpartofthelathe(somepaintmayhavetoberemovedforareadingtotakeplace)Youshouldgetareadingofzeroohmsorabeep if themeterhasacontinuity rangeYoushouldalsobe sure that the electrical sockets on the wall are correctlyearthedIfindoubtconsultacompetentelectricianLightingandelectricheatingshouldbeonaseparatecircuit

tothemachinessoyouwillstillhavelightifthemachinestripoutPlugasmalllightintothemachinecircuitsoyouhavesomelight if the lighting circuit trips out When I go on holiday Ialwaysturnoffthefusetripsforthelightinginordertomakeitmore difficult for intruders to move about quickly Leave thehouse alarm and smoke detectors on (The house alarmmayactivateeighthoursafter theelectricity is turnedoffwhenthebatteryexpires)

Adigitalmultimeterisveryusefulinthehomeworkshop

BeAware

Bementally alert while using the lathe Avoid operations thatmightputyourhandsatriskofenteringthemovingpartsofthelathe Do not operate any lathe while under the influence ofdrugs alcohol or prescription medication that may causedrowsinessorotherwiseaffectyourability to control the lathesafelyDonotattempttoworkonalatheandtalkatthesametimeIfyouhavetotalktosomeoneswitchoffthelathebeforedoingso

KeepItClean

TheareaaroundalatheshouldbekeptfreeofobstructionsThefloorshouldbecleananddrywithanyoilorotherspillscleanedup immediately The lathe should be kept clean and tidyMachinedangerareasshouldbemarkedontheworkshopfloorand observed Workbenches placed near a lathe should be

strongandequippedwithanon-slipsafetysurfacetostoptoolsor other items rolling onto the floor a rubber car mat willsufficeA rubberdoormat on the floorwill allow swarf todropthrough in order to save you getting swarf embedded in thesolesofyourshoes

Asuitablefloormatwillallowswarftodropthroughandhelpkeepyourfeetwarminwinter

LearntoUsetheLathe

Donotuseany lathebeforeyouare familiarwith thecontrolsandareawareofthedifferentwaysofstoppingitThismaybea clutch an onoff switch a No Volts release switch or anemergency stop button I strongly advise fitting a No VoltsreleaseswitchifyourlathedoesnothaveoneAswellasbeingusefulforstoppingthelatheinanemergencyitwillpreventthelathefromstartingupbyitselfafterapowercutIfyouarenotcomfortableworkingwith electrical equipment get a qualifiedelectriciantofittheswitchforyou

StaywiththeLathe

Nevereverwalkawayevenforamomentwhilethelatheyouare using is switched on Switch it off if you are leaving itunattended and only leave the lathe after it has come to a

completestopNeverleavealatheinanunsafeconditionMakesure that you have not left the chuck key in the chuck Thechancesarethatifyouarehalfwaythroughsettingupthelathewhen you return you will forget what you have or have notdoneIfindoubtleaveabignoticeremindingyourselftocheckthatthelatheissafebeforecontinuing

Donotleavethechuckkeyinthechuck

SwitchOffwhenAdjustingtheLathe

Shut off the power supply to the motor before starting anyoperationsrequiringaccesstothelathesuchaschangingtoolsmeasuring work mounting or removing accessories changingspeed and setting up change gears The lathemust be safelystopped Just zeroing a variable-speed drive is not safelystoppingitusethezerovoltsswitchtoswitchthepoweroffaswell

CheckbeforeStartingtheLathe

AlwaysrotateyourworkpiecebyhandtomakesureitclearsthetoolrestsaddleandbedDoublechecktomakesureyourworkis securely clamped in the chuck or between centres beforestartingthelatheBecertainthattheworkpieceturnsfreelyand

isfirmlymountedThespeedofthelathemustbecheckedbeforeturningiton

When turning irregular shapes start the lathe on a low speedandincreasethespeedbyapulleystepeachtimeIfthelatheisbouncingabout lowerthespeedandorbalancethework Ifthe work vibrates stop the lathe and check the reason ThechancesarethatyouarerunningthelathetoofastMeasuringequipment toolingandworkpiecesshouldnotbe

leftona latheastheycanvibrateoff intomovingcomponentsand be thrown around the room Check for loose items on alathebeforeuse

UsetheLatheGuards

NewlatheswillbefittedwithguardsoverthemotorshaftdrivebeltandspindlepulleysTheseguardsshouldalwaysbeinplacebefore using the lathe Any other moving parts should beguardedtopreventanythingfallingontothemovingpartsAlthoughguardsareoften removedbymachinistsprovided

they are constructed from clearmaterials and open and closeeasily theyaddsafetywithout interferingwith theworkbeingdone Guards will at the same time deflect swarf and anycoolantthatisbeingusedGuardsfittedtothelatheshouldnotbe removed while it is in use They should be made fromsuitablematerialandnothavesharpedgesTheyshouldnotberemovedforadjustmentandlubricationofthelatheunlessthisis unavoidable Lathemanufacturers donrsquot usually supply chipguards soaddingoneshouldbeconsideredChipguardswithmagnetic bases are available although they can attract steelswarftothemagnetPutthebaseintoaplasticbagtoaidswarfremoval

UseEyeProtection

Lathes can throw sharp metal chips considerable distancesespecially at high cutting speeds Apart from deep cuts thechipsmay leave the tool red hot cause skin burns and even

burnholes in clothing Youmust use safety goggles or propersafetyspectacleswhileintheworkshopAlwayswearindustrialqualitysafetyglassesfittedwithsideshieldsSpectacleswithoutsafety lenses are not adequate eye protection When theglasses get dirty do not wipe them off as they will becomescratchedWashthemoffunderthetapinstead

TakeCarewhenRemovingSwarf

Do not attempt to remove chips or turnings with your handsAlwaysswitchoff the lathefirstandeitherpull theswarfawaywithalargemetalhookorliftitoffusingapairofglovesIftheswarf is tangled around the lathe untangle it with a pair ofpliersandnotaglovedhandasitwillcutstraightthroughtheglovesandintoyourhandUseadustpanandbrushtoremovesmall chips and swarf from the swarf tray ndash never use yourhandsWhenswarfbecomesstringyandbuildsuponthetoolortoolpostturnoffthelathebeforeremovingit

AvoidLooseClothing

IfyouarenotwearingoverallswearshortsleevedshirtsorrolllongshirtsleevesabovetheelbowsLoosesleevescancatchonrotatingworkandquicklypullyourhandorarmintothe latheObviously though keep your arms protected if hot swarf isflyingaroundSwarf can get inside protective clothing especially collars

(useaclothespegtokeepyourcollartight)pocketsandshoesTostopthesleevesofanoverallcatchingsewelastic intothecuffsorwrapacoupleofthickelasticbandsaroundthecuffstostopthesleevesgettingcaughtupUnder no circumstances wear a necktie when operating a

latheProtectiveglovesshouldneverbewornwhileoperatingalathe Protective gloves may be worn when swarf is beingremovedbuttheymustberemovedbeforeswitchingthelathebackon

UseSturdyFootwear

WearsteeltoecapsafetybootstheyarenotexpensiveandwillhelptoprotectyourfeetfrominjuryifyoudropaheavyobjectonthemThelsquotrainerrsquoversionisparticularlycomfortableDonotallow stringy swarf to fall on the floor as youwill get cuts onyouranklesandmayeventripoverit

AvoidJewellery

Do not wear wristwatches rings or jewellery when in theworkshop as it could catch on a rotating part of the lathe orworkpieceThisalsoapplieswhenmovingalatheintooroutoftheworkshopsincetheycouldcatchona falling lathe IfyourotherhalfcomplainsthatyouhavetakenoffyourweddingringexplainthatyouwouldnrsquotbeabletowearitagainifyourfingerismissingduetoanaccidentLonghairshouldbetiedbackasyoucouldbepulledintothelatheifitgetscaughtintherotatingwork

LiftingintheWorkshop

Back injuries can be caused by incorrect lifting practices It isimportant to bend your legs when lifting rather than bendingyour back A hoist or engine lift should be used to lift heavyitems A stool in theworkshopwill take the pressure off yourlegs and will provide a welcome break after you have beenstoodatthelatheforawhile

Self-ignitingMaterials

If you machine titanium or magnesium which can ignite andburn vigorously keep the accumulation of turnings to aminimum If thematerialdoescatch firedonrsquotusewaterorawater-based coolant as an extinguisher since it will makematters much worse Before starting to machine titanium ormagnesiumfillalargebucketwithdrysandcoveritandkeep

it by the lathe The sand will smother the flames veryeffectivelyYoucouldalsobuyoneofthespecialfireretardantsusedinindustryBeware also of grinding aluminium on the bench grinder

Aluminium and steel filings are the ingredients of Thermite apowerful explosive that can also burn If you grind aluminiumandthenchangeovertogrindingsteeltheredhotsparksareliable to set the steelaluminium mix on fire This is a verydangerous combination ofmaterials and should be avoided atallcosts

SafetywithBarStock

Bar stock should be contained within the headstock and notallowed to protrude from the rear of themandrel I once sawsomeone switchona lathewhenabrassbarwas stickingoutfrom the back of the headstock by about two feet With thelathe running at 2000rpm the bar whichwas aboutfrac34in (19mm) in diameter was bent at right angles and caused theheavy lathe which weighed 1280kg to jump about Luckilysomeone managed to switch the lathe off before any majordamageoccurredItwasnottheoperatorhehadrunwellawayandwasnowheretobeseen

SomeFinalWordsonSafety

Wherever possible the machine height should be adjusted tosuittheuserWearestillusingfifty-year-oldmachinesbutfiftyyearsagothenationwasshorterTheworkplaceshouldbeprovidedwithuniformlightingthat

gives an adequate level of illumination Individual machinelightsarebestThe lathemust be set to operate at the speeds and feeds

recommended for thespecificmetalbeingturned If themetalrotatestooslowlyortooquicklyorthefeed istooslowortoofastaccidentsarelikelytooccurThe area directly in front of and behind the workpiece is

known as the lsquofiring zonersquo or the lsquored zonersquo This is where apiece of work is likely to go as it leaves the lathe Make it ahabit to keep clear of this zone when you turn the lathe onLearnwhere theNoVolts switch is as youmightneed to turnthelatheoffquicklyByfollowingalltheaboveadviceyoushouldnowbeableto

worksafelyfullyawareofanysafetyproblemsthatmightariseAtthispointyounowknowhowtoinstallthelathelookafter

itclean itandmaintain it InChapter3wewill lookatcuttingtoolsandexaminehowtoselectcuttingspeedsandfeeds

Thisbarisstickingouttoofarfromthebackofthelathe

3CuttingToolPrinciplesFeedsandSpeeds

The first part of this chapter will look at the materials fromwhichcuttingtoolsaremadeaswellastheirbasicshapeandgeometryWewill thenconsider selectingsuitablespeedsandfeeds

MAINTYPESOFTURNINGTOOLS

There are three main types of turning tool used in modernworkshops HSS (high speed steel) tools carbide brazed-ontoolsandinsertedtiptoolsAllhavetheirusesintheworkshopandformost jobsthere isnopreferenceforonetypeovertheothersTherearealsocarbonsteeltoolbitsalthoughinpracticetheyarejustaboutobsoleteCarbonsteeltoolscanbemadeinthe homeworkshop but apart frombeing used tomake formtools(seeChapter11)thereaderisunlikelytousethismaterialfortools

Ageneral-purposeHSSturningtoolsuitableformildsteel

HSSTOOLS

HSStoolscanbepurchasedsinglyorinsetsalreadygroundtothecorrectshapeIt ischeaperhowevertopurchasethemassquare tool blanks in various sizes ready for you to grind toshapeThecompleteready-groundsetswillprobablycomewithseveralshapesincludedthatyouwillneveruseIfyoucanbuyafewready-groundtoolscheaplytheywillbeofuseasguidestoseehowtosharpenyourownHSStoolblanksHSS form tools from industry are often available second-

handTheseareespeciallygroundtomachineacomplex formall in one go You can often find some that are ground to asuitable shape to form the end of a threaded componentincludingtheundercut

HSSformturningtools

Brazed-onCarbideTools

Brazed-on carbide-tipped tools are quite useful especially forfacing and boring cast iron but they really need a diamond-facedgrindingwheeltokeepthemsharpCarbidetipsandtoolscomeinvarioussizesandhardnesstosuitindividualmaterialscarbidetoolsforsteelwilloftenbepaintedbluethoseforcastiron are painted red and those for stainless steel are paintedyellowThecolourindicatesthesuitabilityofthetoolforcertainmaterials

Brazed-oncarbide-tippedtoolscomeinvariousgradesshapesandsizes

InsertedTipTools

InsertedcarbidetiptoolsareveryusefulbuttheyarenotcheapThe tipsarenotusually sharpenedafterwearingout you justthrow the tip away and fit a new one Most modern carbide

inserts however do have more than one cutting facesometimestheyhavetwoandoccasionallyfourormorecuttingedgesareavailableYoucanevengetformturningtoolswheretheinsertisroundandcanberotatedafull360degrees

Theleft-handtoolisblueindicatingitisformildsteelwhiletheright-handtoolisredindicatingitisforturningcastiron

Some diamond-shaped tips can be used in different toolholders two edges are used in one tool holder and the othertwoedgesareusedinanothertoolholdersoyougettwicethelifepertipInserted tip tools are available for internal and external

screwcuttingwherethetipsareheldat thecorrecthelixangleofthethreadinthetoolholderThedrawbackisthecostofthetipsandeachsizeofthreadusuallyneedsitsownsizeoftip

Aninsertedtipcarbideturningtool

Carbidegroovingtools

InsertedtipgroovingtoolsareidealformachininggroovesforOrings and circlips Theyare available inmany standardwidthsandcanoftenbeusedasparting-offtoolsforsmallerdiametersOneof themostusefulgrooving tools forsmallersizegroovesandpartingoffistheMiniThinsystemassoldbyMSCIndustrialSupplyCo

TheMiniThintoolholderisidealforgroovingandalsoforpartingoffsmalldiametersTheshankissostrongcomparedwiththecutbeingtakenthatusinganoverhangasshownisquite

safe

Coatingstoreducetoolwear

Tipsarealsoavailablewith various coatings that improve toollifeThemostcommoncoatingistitaniumnitride(TiN)whichisgold in colour Other coatings that offer slightly better wearresistancearetitaniumcarbonnitride(TiCN)whichisbluegreyincolourandtitaniumaluminiumnitride(TiAlN)whichisvioletbronzeReady-groundHSScuttingtoolssuchasdrillstapsandreamers are also available with these coatings but once yousharpenthecutterthecoatingisgoneTipped toolsneedadeeper cut ahigher feedandahigher

speed than HSS tools Thismeans that the lathe needs to bestrongrigidandhaveamplepowertodrivethe lathemandrelwhen taking a heavy cut this rules out using tipped tools onlathessmallerthanabout2in(50mm)centreheightSmaller tools are made to fit the Unimat and similar small

lathesbutthesemachinesjustdonrsquothavethepowerneededtodrivethemAtbesttakingacutwillstopthelatheatworstthetoolwillchip

Insertedtiptypes

Inserted tip tools come in many shapes and sizes Some tipshapes and sizes are made to an international standard andothers are to the makerrsquos own standards Wherever possibleuse ISOstandardtoolsas thetipswillbe interchangeablewiththosefromothermanufacturersandwillprobablybecheaperaswell The ANSI system commonly used in the USA is notcompatiblewiththeISOsystemusedintherestoftheworldIfyour lathe ispowerfulenoughyoucantakeadvantageof

insertedtippartingoffbladesThesearemounted inaspecialtoolblockandthebladecanbeslidinoroutdependingonthediameteryouarepartingoffThebladecarriesan inserted tipspecially designed for parting off There are three types of tipavailablesquare-endedtipstipsthatareangledtotheleftand

tips that are angled to the right Square tips are used forgeneral parting off tips angled to the left are usedwhen youdonrsquotwanttoleaveapiponthebackendoftheworkandtipsangledtotherightareusedwhenyouwantacleanfaceonthefrontoftheworkThe parting off blade is oftenmounted upside down at the

backofthe lathecrossslideTheactionofpartingofftendstolift the whole cross slide slightly and forces the cross slidetightly into thematching dovetail whichmakes itmuchmorerigidIfthepartingofftooldigsinwhileinthebacktoolpostthetool tends to lift and push away from the work whereas in afronttoolpostthetooltendstodiginandpullintothework

Simplifieddiagramofpartingofftoolangles(A)straightpartingtool(B)angledtotheleft(C)angledtotheright

POWERREQUIREMENTS

Whenturningmildsteelorstainlesssteelwithanycarbidetoolthe machine horse power required is considerably more thanthat required forordinaryHSStoolsThe twomain reasons forthisarethatcarbidetoolsoftenhaveanegativerakeangleonthecuttingedgeasthistypeofedgelastsmuchlongerthanapositiveangle especially for intermittent cuts andbecause in

industrial use carbide tips are called on to remove largerquantitiesofmetalathigherspeedsandfeedsFor guidance on using tipped tools in the small workshop

wheretimeisnotasimportantasinanindustrialenvironmentIwould recommendusing twice the speedused fornormalHSStools and a fine feed of about 0002in (005mm) per rev as astarting point This can be adjusted up or downdepending ontheresultsThemaindifferencebetweenHSStoolsandcarbidetippedtools(eitherbrazed-onorinsertedtip)isthehorsepowerrequirementofthemachineinuse

Thispartingofftoolismountedatthebackofthelatheinaspecialbacktoolholder

SELECTINGTHECORRECTSPEEDSFORDIFFERENTMATERIALS

Overmanyyears through trialanderror cuttingspeedshavebeendeterminedthatgiveanoptimumtoollifebalancedwithadecent surface finish These speeds are normally quoted inlsquosurfacespeedinfeetperminutersquoSpeeds and feeds used on industrial machines where the

primary tools will have inserted tips will be a lot higher than

thoseusedinthesmallworkshopwhereHSStoolsarethenormThe accompanying table gives an idea of the speeds that

shouldbeused forvariouscommon typesofmaterial likely tobefoundintheworkshopThespeedslistedshouldbesuitableforbothturninganddrillinginthelatheForreaminguseabout25percentoftherecommendedspeedsThe table is a guide only and it is likely that the machine

speedsavailablewillnotbeexactlythoserequiredandyoumayhavetoresorttolsquonearenoughisgoodenoughrsquoSetthelathetothe nearest speed lower than indicated in the table for thediameterandmaterialbeingcutThiswillbefineforHSStoolsDouble the recommended HSS speed for carbide tools For

parting off use about 30 per cent of the recommended HSSspeed For form tools use about 50 per cent of therecommended speed for the initial cuts and then engage thecorresponding back gear (just switch to back gear leaving thebelts on the same pulley) and gently tap the handle until itreachesthefinishedsizeandallowittofinishthecutbyitselfYou may have to adjust the speed down if you get a lot ofchatter

Forturningcastironuseacarbide-tippedtoolrunningattheHSSspeedtoremovetheskinYoucanthenfinishtheturningwithaHSSsteeltoolifyouwishPlease remember if doing any work that might be

unbalancedstartoffslowlyandincreasethespeedabeltstepatatime

THEACTIONOFCUTTINGTOOLS

Basicallya lathe tool isawedge that is forced into theendofthe rotating bar to remove metal As long as the tool is fedforwardwhilethelatheisrotatingmaterialwillberemovedA typical right-hand turning tool has a cutting angle of 90

degreeslessthesideclearancelessthesiderakeThecuttingangle for this example is 90ndash10ndash10= 70 degrees This is theangle that is wedged into the work to remove the materialSoftermaterialswillhaveasmallercuttinganglewhilehardermaterials will have a larger cutting angle Tool angles varydependingonthetypeofmetalbeingturnedToolsforturningsofter metals usually have higher rake angles than thosedesigned for harder metals since a turning tool will normallyholditsedgeforlongerinsoftermaterialsBrassalthoughsoftusuallyhasnotoprakeonthetoolatallOther angles to be aware of are the top rake and the side

rake

CUTTINGTOOLSHAPES

The followingaresomeof thedifferent shapes thatyoumightfindusefulforgeneralturningandmetalremoval

Right-handknifeturningtoolAllrakeanglesare10degrees

Right-hand knife tool This is used for general turning andfacingofbarstockDependingontheworkyouaredoingyoumayfindaleft-handversionofthistooluseful

Typicalroughingtool

Right-handroughingtoolIthasaleadingangleandasmallradius on the tip of the tool This tool is used for fast metalremovalwherefinishisnottooimportantAgainyoumayfindaleft-handversionusefulAroughingtoolcuttingatanangletoabarwillremoveachip

widerandthinnerthanatoolcuttingat90degreestothebarThis improves tool life although you will have to square theturningupwithastandardknifetool

Typicaldouble-sidedroughingtool

Double-sided roughing tool It can turn towards the left orright It canalsobeusedasaplunge tool to removematerialfroma groove orwhere the component needs to be lsquowaistedrsquodown

Simplepartingofftool

Simple parting off tool This is suitable formostmaterialsYouwillprobablyneedalargeoneforpartingofflargediameterbarsaswellasasmalloneforpartingoffsmallcomponents

Internal(top)andexternal(bottom)screwcuttingtools

ScrewcuttingtoolThisisusedforcuttingscrewthreadsTheanglewilldependonthethreadyouarecutting60degreesformetric55degreesforWhitworthandBSFetc

Shallowboringtoolcapableoffacingacrossthebottomofahole

Boring and facing tool This toolrsquos unusual shape will befound very useful when recessing a large bore It will plungestraight intoasmalldrilledholeandwillalso face rightacrossthebottomoftherecess

Double-endedchamfertoolchamferingadiameter

Double-ended chamfering tool It has 45 degree angles atbothendssoitcanbeusedtochamferexternaldiametersandinternalbores

Double-endedchamfertoolchamferingabore

Othershapescanbeusefulbutthetoolsshownhereshouldbesufficienttogetyougoing

BORINGTOOLS

Boring tools are used to clean up a previously drilled holepossiblytomakeitruntruebutmorelikelytoensuretheholeistothecorrectsizeTheyarenormallylongerthanordinarytoolsandtendtostickoutfurtherfromthetoolholderHSStoolsaresuitableformostusesCarbideinsertedtipboringbarsarealsoreadilyavailableandarethebestbetforturningcastironinthesmallworkshop

HSSboringbar

For really small holes down to2or3mm indiameter solidHSSandcarbideboringbarsarereadilyavailableAlthoughtheyarenotcheaptheywillbefoundveryusefulandquicktouseAnothermethodofboringahole is tousea longseriesslot

drillasaboringtoolInuseclamptheshankinthetoolholderwiththepointatcentreheightmakingsuretherestoftheslotdrillisclearofthesideoftheboreYoucanthenrunitthroughtheboreinasimilarmannertoastandardboringbar

Asmallcarbideboringbarinsertedintoamildsteelshank

PARTINGOFFTOOLS

PartingofftoolsprovideaquickwayofcuttingoffworkfromtheparentbarThereisrarelyanyneedtoworryaboutcuttingthecomponentofftothecorrectlengthtogetagoodfinishAslongasthecomponentislongerthanrequireditcanbeputbackintothe chuck or a collet and the parted off face can be faced tolengthorotherwiseworkedonThepartingofftoolcuttingfacecaneitherbesquareoritcan

beangledtotheleftorright(seepage43)Thesideofthepartingofftoolcouldevenberadiusedsothat

it forms a radius on the end of the next component orchamferedtoformalead-inedgeforthenexttool

CUTTINGLUBRICANTS

Tomake cutting tools cut easily and to prolong their life it issometimesbesttouseacuttinglubricantForsteelIpreferneatcuttingoilItlubricatesbutisnotidealforcoolingtheworkIn industry coolant is normally used This is oil that has an

additivetomakeitsolubleinwaterMostsolubleoilswilldobutthe synthetic ones tend to sting your hands if you have anyopen cuts I would not recommend using soluble oils on thehome workshop lathe as I think they tend to wash thelubricating oil off the slideways and can encourage rustHowever this ismypersonalpreferenceandmanypeopleusesolubleoilinthehomeworkshopwithoutanyproblemsOil is suitable for use when cutting steels mild steels

stainlesssteelsandhighcarbonsteelssuchassilversteelThebestlubricantwhencuttingaluminiumisparaffinItstops

thealuminiumfrombuildinguponthecuttingtoolBrassandcast ironarenormallycutdryWhenturningcast

ironona lathe if the latheisfittedwithasolubleoiltankthecastirondustwillhaveanaffinityforthesolubleoilIfthelatheisthenusedonaluminiumthefreecarboninthecast ironcancontaminatethealuminiumwithblackstreaks

Inormallyplacetheoilorparaffininasmalldish(actuallyacatordogfoodbowl)andapply itbyhandwithasmallbrushThisdoesallIneedThenextchapterlooksatgrindinglathetools

4SharpeningToolsandHoldingThemintheLathe

ThenexttaskistogrindasetofusefullathetoolsThe first thing you will need is an off-hand grinder The

grindercanbeadangerousmachineso itshouldbeusedwithcare Eye protection must be worn the guards should becorrectlyfittedandtheremustbeadequateilluminationIdonrsquotlike using a grinder in a small workshop as the grinding dustflies everywhere and canget onto themachine slideways andtools generally making the workshop dusty and dirty Ifpossible set up thegrinder in a separate areaaway from theworkshopIhavemygrindermountedonafoodchoppingboardso I can carry it outside to use This has the addedbenefit ofdaylight although you are dependent on the weather or youmightneedtouseitafterdark

Theguardofthisoff-handgrinderhasbeenwidenedtoacceptarecessedwheel

GRINDINGWHEELS

IthasalwaysbeenstatedthatyoushouldnevergrindatoolonthesideofthegrindingwheelSofollowingthistheorywewillbeusingarecessedwheelwhereitswidthismuchthickerthanthepartofthewheelusedtoclampthewheeltothegrinderIstruggledtofindarecessedwheelof6in(150mm)diameterandfinally found a 60 grit grinding wheel on a personal visit toAxminster Power Tools in Devon (I could find only an 80 gritwheel in theircatalogue)Thewheels I like touse forgrindingare A60K5V if I can get them and I prefer the white wheelsdesigned for the harder tool steels rather than the grey orbrown wheels which are more suitable for softer mild steelsThedesignationbreaksdown like thisA stands foraluminiumoxide 60 is the grit size K is the hardness (I J and K beingmediumhard)5 is thestructure(thespacebetweengrainsofgrit) and V is for vitrified the method of bonding the grainstogetherTheKandthe5canvaryabiteitherwayandthegrit

shouldbe4660or80with60beingpreferredThe80gritisabitfineandwillclogupquitequicklySo-called green grit wheels made from silicon carbide are

available for sharpening carbide tools They are usually softerthanaluminiumoxidewheelsinordertoallowthegrittobreakdownbeforethewheelbecomesglazedfromgrindingthemuchhardercarbide

Witharecessedwheelyoucancutontheouterfaceoftherecessedsideofthewheel

TestingtheWheel

The first thingyoushoulddowhenbuyingawheel is tomakesurethat it is ratedatasufficientlyhighspeedfor thegrinderon which it is to be used Off-hand grinders usually run ataround2900rpmsoyouwillneedawheelratedtoatleastthatspeed it is all the better if the grinding wheel is rated at ahigher speed than the grinder Care should be taken whenhandlinggrindingwheelsastheyarequitefragileifknockedordropped A grinding wheel should only be purchased from areputableengineeringsupplierSupportyourgrindingwheelona piece of wood and tap the wheel gently with a plasticscrewdriver handle or similar The wheel should lsquoringrsquo if itsoundsdullitshouldbebrokeninhalfandeitherthrownawayorusedontheworkbenchasasharpeningstoneNeverthrowawheelawaywithoutbreaking it into twoyouneverknowwho

mightgettheirhandsonit

Thistoolrestwasdesignedtosharpenplaneironsandchiselsbutitisfineforlathetools

Amoderndigitalanglegaugeisidealforsettingthetoolrest

MountingtheWheel

The wheelrsquos bore should be the same as the spindle of thegrindingwheelOften theborewillbe largerandyouwill then

need some plastic spacers to reduce it Spacers should bereadilyavailable fromyour localengineeringsupplierYoucanturn thespacers fromplastic if youcanrsquotbuyany ready-madeonesAt each side of the wheel you should fit a paper washer

thesearemadeofblottingpapertypematerialandwillprobablyhave been supplied already stuck on the wheel The grindershould have twometal flanges one to fit at each side of thewheel Both flanges should be the same diameter These willhold the wheel true and spread the tightening load on thewheelThegrinderwillhavetwodifferent threadsontheendsof its spindle The right-hand side of the grinder will have aright-hand thread and the left-hand side will have a left-handthreadThedifferentthreadsaretostoptheclampingnutsfromunscrewingwhenthegrinderisrunningTofitthewheelremovetheguardandundothenutRemove

the metal flange and then the wheel Make sure the flangesdonrsquothaveany remainsof theoldpaperwasheron themPutthenewwheelontothegrinderspindle(rememberthespacerthepaperwashersandtheflangesateitherside)andscrewthenuthand-tightFinallyholdthewheelgentlyandgivethenutapinchupwithaspannerYoudonrsquotneedtoover-tightenthenutjustsufficiently tostop thewheel fromcoming looseRefit theguard and spin thewheel by hand to ensure it is not rubbinganywhereNowwearealmost ready to switch thegrinder onBeforedoingsohoweverputonyoureyeprotectionandstandtoonesideofthegrindersoyouarenotinlinewiththewheelshould it burst Then switch the grinder on All should be fineandthewheelshouldberotatingsafely

TOOLREST

Theworkrestsuppliedwithanoff-handgrinderisusuallyjustabitofbentsheetmetalboltedonItisusablebutonlyjustI recently purchased a ready-made tool rest as a basis for

makinganimprovedgrindingrestThiswasoriginallydesigned

forsharpeningplanebladesandchiselsforwoodworkingbutitmakes an ideal rest for sharpening lathe tools It is made ofaluminiumandisfullyadjustableforangleThebestmethodofsetting the rest to the correct angle is to use a digital anglegauge These are now very cheap and are readily obtainableThepositionoftherestinrelationtothegrindingwheelcanbeadjusted on its sliding base Many designs for tool rests havebeenpublishedandyoucouldmakeoneofthoseinsteadifyouwishtosavemoneyThetoolclampassupplied isdesignedtoclampplane irons

andchiselssothisneedstobechangedLathetoolsneedtobepresented to the grinding wheel at the correct angles If youdonrsquot have a digital angle gauge this can be achieved usingsimpleguidesmadefromanglesheetmetalandsomescrewsIused gauge plate made from a high carbon steel with anaccurategroundfinishthatcanbehardenedandtemperedbutmild steel would be perfectly suitable if you donrsquot have anygaugeplateavailableYouwillfindaprotractorusefulyoucangetasteelonewith

an adjustable blade for a reasonable price The protractorwillbeusedtosetthetoolanglethatisgroundonthetools

Sheetmetalprotractorsareavailableverycheaply

LATHETOOLGEOMETRY

LathetoolsneedtobegroundtocertainanglesbuttheanglesdonrsquothavetobeexactFormosttoolssomewherehandywilldounless you are grinding a form tool to a particularly accurateshapeIthasbeennormalforbookstoshowtheanglesontoolsas used in a production environment where tools will ideallyhavealonglifeoftenthislifeiscalculatedaslastinganeight-hourshiftsothetoolonlyhastobesharpenedandresetonceadayInthehomeworkshopwecan increasethesecuttingangles

andgetbettercuttingattheslightexpenseofshortertoollifeWehavealreadyexplainedtheshapesof the tools thatyou

willfindmostusefulToolanglesareknownbytechnicaltermstop rake front rakeside rakeandback rakeThe rakeanglesvary depending on thematerial to bemachined but a set ofstandardtoolswillgetyoustartedSomeoftheaccompanyingphotographsareactuallyoflarge-scalewoodenmodels

Theleft-handtoolissuitableforbothfacingandturningtheright-handtoolissuitableforturningonly

Left-handsideofthefacingandturningtoolshowingthefrontandtoprake

Topofthefacingandturningtoolshowingthefrontandsiderelief

Left-handsideoftheturningtoolshowingthefrontclearanceandthetoprake

Topoftheturningtoolshowingthefrontandsideclearanceandthetoprake

GRINDINGATOOL

WhengrindingHSStoolstrytokeepthemascoolaspossibleIfan HSS tool becomes too hot and is then quenched in waterminutecrackswillformonthecuttingedgesThesecrackswillmakethetoolcuttingedgebreakdownveryquicklywhenusedThe best practice is to grind a little bit off the tool and thenquenchitwhileslightlywarmDonotletthetoolgethotdipitin thewater little andoften This should ensure the tool edgedoesnotbreakdowninuse

GrindingYourFirstTool

Most angles can be ground by using the tilting table whileothersmayneedtobefixedinrelationtotheperipheryofthegrindingwheelThefrontandsideofthetoolcanbegroundbytippingthetableatthecorrectanglewhereasthetoprakecanbegroundontheperipheryofthewheelThegrinder should first be switchedoff andunplugged Set

thetoolresttotherequiredangleusingthedigitalanglegaugeoranangletemplateandtightenuptherestBefore switching on the grinder ensure that everything is

freetorotatebyspinningthegrindingwheelbyhandIf all is well put on your safety glasses and switch on the

grinderPlacethetoolonthetoolrestupagainstthesideoftheprotractor Slide the tool along the table until it reaches thegrindingwheel andmetal starts to be removed Slide the toolbackwards and forwards slowly along the restwhile putting alittle light pressure on the tool so that it continues to pressagainst the grinding wheel When you have removed a smallamountofmaterialcoolthetoolbitdownAtnotimeallowthetool bit to get hot Continue grinding until you have removedsufficientmaterialfromthetoolbit

Thegrindingrestissettothecorrectangleof10degreestogrindtheendofthetool

Grindingthefirstangle

TurnthetooltotheotherangleanddothesamesothatnowboththefrontandsideclearanceangleshavebeengroundThis toolwill be enough for brass but for steelwe need to

grindthetoprakeWhengrindingthetoprakeonaright-handtool the slide rest needs to be higher than the centre of thegrinding wheel so that it grinds the tool at approximately 10degrees

Thefirstanglehasbeenground

You have now ground your first lathe tool The tool asreceivedfromthegrinderwillbetooroughtousehoweversoyouwillneedtohonethecuttingedgesYoucandothisonanoilstone(usedwithfineoillike3in1)orwithadiamondlaporusing a combination of the two Lightly lap the front and sideclearanceanglesuntilyougetagoodfinishand lightlyhoneaverysmallradiusonthetipofthetoolFinallyhonethetoprakeangleandyourtoolisreadyforuse

Grindingthesecondangle

Thesecondanglehasbeenground

AllofyourHSSturningtoolscanbedoneinthiswayOnlytheangleswillvaryandthesecanbesetusingadigitalanglegaugeandprotractorAnoccasionalhonewillresharpenyourtoolsaslongasyoutreatthemwithcareA similar range of HSS tools and a parting off tool all with

zero top rake shouldbeavailable if youwill be turningbrassUnless you are doing quantity production one tool holdershouldbesufficientforbrassAsatoolforbrasshasnotoprakeandyouwouldnotnormallygrindthetopawayaslongasyoubuy tool steel of the same size the tip height will remain thesameYoucanthenusethedifferenttoolsinoneholderwithouthavingtoresettheheight

MACHININGCASTIRON

Carbide-tippedtoolsareidealformachiningcastironAsimplebrazedupcrankedtoolwithasmallchamferonthenosewilldoforbothturningandfacingcastironcomponentsThemainuseof this tool will however probably be truing up the faceplatethat comes with the lathe The large diameter combined withtheintermittentcutovertheboltgrooveswoulddestroyanHSStoolinafewsecondsAsmalltippedboringbarwillbeidealfor

taskslikeboringcastironcylinders

Grindingthethirdangle

Asimplediamondlap

Thethirdanglehasbeenground

Tosharpentippedtoolsyouneedadiamondwheelorifyouwant to remove large amounts of carbide a silicon carbidewheeloftencalledagreengritwheelowingtoitsusualcolourSilicon carbide wheels are much softer than aluminium oxidewheels as they need to break down faster to present newsharpergrainstothecarbidetoolAdiamondwheelisonlydesignedtolightlylapatippedtool

itisnotsuitableforremovinglargeamountsofcarbide

Diamondcupwheel

TOOLHOLDING

Smallerlathessuchasarefoundinmostworkshopsmayhaveatopslidewithatoolclampforindividualtoolsablockwithasingle slot to take the tool a four-way turret (or sometimes athree-way)oraquick-changetoolblockandholdersetThereisalsotheso-calledAmericantoolpostwhichisaroundbarwitha slot through it and a bolt in the top to clamp the tool ItusuallycomeswithmatchingdishedwasherstoadjustthetoolheightThistypeisnolongerverycommononlathes

Quick-changeToolPost

Themostversatiletoolholdingsystemisthequick-changetoolblockwithmatchingholdersThedrawbackwiththissystemisthe cost of extra tool holders you need quite a few one foreachtoolThequick-changetoolblockmountsonthefrontofthelathe

normallyontopofthetopslide(Blockscanbefitteddirectlyon

thecrossslidebytheuseofaraisingblocktoaidrigidity)

Quick-changetoolblock

Each holder is set up with its own particular tool The toolholderscanbe individuallysetso that the turning tool isdeadoncentreheightandispresentedcorrectlytotheworkpiece

Quick-changetoolholder

Quick-change tool holders are available with a straight cutslottotakestandardsquareshanktoolholderswithastraightcutwiththeadditionofaVeecut-outinthebottomforusewithroundtoolssuchasboringbarsandasafrontpartingoff tool

holdertotakeahighspeedsteelpartingoffbladeRearpartingoff tool holders are available to take an inverted parting offbladeeitherahighspeedsteelbladeoran insertedtipbladeLeft-handed and right-handed extended tool holders are alsoavailableandmayoccasionallybequiteusefulThetoolblock isnormallymountedonthetopslidebutyou

cangetraisingblockstouseinsteadofthetopslideThismakesthetoolholderblockmuchmorerigidAbackquick-changetoolblockwillneedmountingonaraisingblock

Backofaquick-changetoolholdershowingthedovetailtypeofmounting

Right-handandleft-handextendedtoolholders

StandardtoolholderwithaVeetotakeroundtoolholders

Frontpartingofftoolholder

ToolClamp

Satisfactoryworkcanbedonewithatoolclampedontothetopslideusingshimsteel toset thecentreheightof the toolThemaindrawbacksarethatyoulosethepositionofthetoolwhenyoutakeitoffthetopslidetofitthenexttoolandyoualsolosetheaccuratecentreheightofthetoolunlessyoukeepthetoolandshimstogetherIfyouaremakingonlyonecomponentthisisnotaproblembutitisanuisanceifyouaremakingabatchofmatchingcomponents

Simpletoolclamp

Single-slotBlockToolPost

AblocktoolpostisoftensuppliedwiththecheaperlathesThetoolpostisliterallyablockofmetalwithaslotcutinittotakethe turning tool It is relatively easy to set the tool up at thecorrectcentreheightbyusingvariousthicknessesofshimThisisfineforthebeginnertoturningwhoisjuststartingoutbutitisbesttoreplaceitwithafour-waytoolpostoraquick-changetool post You could of coursemake several block tool postsandkeepeachonesetwithadifferenttool

Four-waytoolpost

Backtoolpost

Four-wayToolPost

Four-wayToolPost

Thefour-waytoolpost isagoodcompromiseona latheasyoucansetfourtoolsintheturretandrotateeachoneintopositionas needed This speeds up production and is a lot faster thanusingasimpletoolclampThedrawback isthatthetoolsstickoutof the turret fourdifferentwaysandyoumightcatchyourhandonasharp toolAsimple ratchetstopensures thateachtool repeats its position when the tool post is rotated so theworkisaccuratelyturnedeachtimethetoolisusedAduplicatefour-waytoolpostwithtoolsforbrasswillspeedupproductionevenmoreCastingsareavailabletomakeyourownthree-waytoolpost The three-way toolposthas theadvantageofbeingable to get close to the work when you are turning betweencentresFor the front tool post I would recommend right-hand and

left-hand roughing tools right-hand and left-hand finishingtools a tool groundup to face barswhile using a half centreand a Mini Thin inserted tip grooving tool with grooving andparting off inserts You will also need large and small boringbarsbothHSSandwithinsertedtipsTheHSStoolsshouldbegroundupforuseasgeneral-purposeturningtoolsformildsteelandsimilarmaterialsThecarbideinsertedtipboringbarshouldbefineforcastiron

BackToolPost

You can fit a quick-change tool block to theback of the crossslideaswellasthefrontSpecialholdersareavailabletotakeaHSSparting off blade or an inserted tip parting off blade Thebladewill be angleddown to give top clearancewhenpartingoffTheseback-mountedtoolblocksareveryhandyastheycanalsobefittedintotoolholderswithafacingtoolorachamferingtoolFor a back tool holder set-up I would recommend an HSS

partingoffbladeafacingtoolforcastironandadouble-ended45-degree chamfering tool that can be mounted parallel with

the chuck or at 90 degrees to it This set-upwill allow you tofaceaworkpiecechamfertheoutsidediameterandortheboreandpartitofftolengthThenextchapterlooksatholdingworkinachuck

5WorkholdingintheChuck

This chapter covers the different types of chucks how to usethemandsetupworkinthemaccurately

Aself-centringthree-jawchuckfittedwithlsquodrilljawsrsquoNotetheexternaljawswhichareinterchangeablewiththedrilljaws

USINGCHUCKS

Themostusefultoolsforworkholdinginthelathearethree-andfour-jaw chucks The three-jaw chuck is usually of the self-centringvarietythistypeofchuckcomesasstandardwithtwosets of jaws The first set of jaws are known as inside or drilljaws as they are most useful for holding round and hexagonbarsTheother setof jawsareoutside jawswhichholdworkusuallyindiscformontheoutsideSelf-centringmeansthatwhenyouinsertabitofbarintothe

chuck and turn the chuck key the chuck centralizes theworkpieceas it tightensup It isunlikely to runperfectly truebutitshouldruntruewithin3or4thouYou can also purchase soft jawswhich are exactly as their

namesuggestsYoucan thenbore themout to fit thework Ifyouborethemonthelatheyouaregoingtousethemontheworkwillrundeadtrue

Asetofsoftjawscanbeturnedorboredtosuittheworktobeheld

Aself-centringfour-jawchuckThesealsocomewithexternaljawsandsoftjawsareusuallyavailable

Self-centring four-jaw chucks can be used for square barsTheyarealsousefulforholdingroundbarswithmoregripthanathree-jawself-centringchuckSoft jawsarealsoavailableforfour-jawself-centringchucks

Afour-jawindependentchuck

Youare howevermuchmore likely to comeacross a four-jaw independent chuck than a four-jaw self-centring chuckIndependent means that the jaws can be moved individuallyand the jaws can also be reversed one two three or four ofthemdependingontheworktobedone

Abaseplatecastinginafour-jawindependentchuck

Wewillfirstlookatthethree-jawchuckThebestmethodofmaking a component in one of these is if possible to turn itcompletely at one set-up If you put a piece of bar into thechuck face the end centre drill drill and ream it skim thediameterandpartitoffitshouldbeconcentricalloverThisisbecausewehaveturneditallatthesamesettingwithouttakingit out of the chuck If we need to machine the other endhoweverwhenwe turn it roundandput it back in the chuckthechancesareitwillnotruntrueThis iswherethe four-jaw independentchuckcomes inYou

canput thecomponent intoa four-jawchuckandset it to runtrueusingthedialtestindicatorAnyworkyoudoonthepartedoff end should then be concentric with the rest of thecomponentWhensettingworkinafour-jawindependentchuckfor a second operation use some thin shimbetween the jawsandtheworkpiecetoavoidmarkingtheworkWorkisoftenheldinafour-jawchuckbecauseitisacasting

anoddshapeorsquareandsowonrsquotfitintoathree-jawchuckIf thework just requires tobe faced flat rightacross the facethereisnoneedtosettheworkrunningradiallytrueItshouldbe near enough on the centre line as long as the work is

reasonablybalancedYou could of course put the component into a three-jaw

chuckbyfittingsoft jawsandmachiningorboringthemouttotake the component This is the best option ifmaking severalcomponentsthatneedtobeidenticalbutifyouonlyneedoneor two components a four-jaw independent chuck will be thequickestmethodofmachiningthemLargerdiameterscanbeheld ina three-jawchuckbyusing

theoutsidejawsThesehavealargeradiusontheinsideofthejaw ifthisradiusis largerthantheworkpiecethejawsshouldnot tend to dig into the work and mark it Outside jaws areuseful forholding components like small flywheels locomotivewheels and chuck backplates when machining the bores ofholesorwhenmachiningacrossthefaceWhenmachining thindiscs it isuseful toputsomepacking

behindthedisctomakeitstandproudofthejawsTostopthepackingflyingoutwhenthemachineisrunningmakeasetofthree or four packing pieceswith grooves at each end and fittensionspringstothemTheyshouldallbethesamediametersothatthebackoftheworkisparalleltothechuckThelengthand grooves can vary slightly as they donrsquot affect theparallelismTheyarequickandsimpletomakesoacoupleofsets of different diameters should find their way intoeverybodyrsquostoolbox

AlthoughmostlathechuckkeyshavesquareendstheyareoftenofdifferentsizesKeepeachkeywithitsownchuck

ChuckKeys

I have alreadymentioned that the chuck key should never beleftinthechuckwhenitisunattended(seeChapter2)PutthekeyintothechuckuseitandputitsafelyawayassoonasyouhavefinishedwithitIfyouswitchonthelathewiththekeystillinthechuckyoumightneedatriptothehospitalDonotuseexcessive forcewhenyou tightenup the chuck

Do not use a piece of tube a spanner or anything else as alever thechuckkeyon itsownshouldbesufficient to tightenthechuckontotheworkWhenusinga four-jawchuckasmallchuckkey littlemore

thanaknurledknobwithasquareoncanbeusedtoadjustthejawsinandoutpriortotighteningupwiththeproperchuckkeyThiswill save timeover adjusting the jawswith a large chuckkeyTo turn the independent four-jaw chuck jaws round a

carpenterrsquosbracewithapieceofsquarebarinittofitthechuckwillmakeshortworkofreversingthe jawsbutdonrsquotuse it forthefinaltighteningasitisliabletostrainthejaws

STARTINGTOTURN

Before going any further you need to learn how to do basicturningFor thisyouneed toput the three-jawchuckonto themandrelStartbycleaningthemandrelwithacleanbitofragorsimilar(Ikeeparollofpaperkitchentowellingintheworkshop)Nowyouneed toclean thechuckrsquosboreand threadusing thetwotoothbrushmethod(seeChapter2)BoththemandrelandthechuckshouldbecleanbeforeyouattempttofitthechucktothelatheSelecting and grinding turning tools has already been

discussed (see Chapter 4) so by now you should have acorrectlygroundturningtoolsuitableforroughingoutapieceofsteelbar

Barwithapiptoolaboveorbelowcentreheight

MakingaToolCentreHeightSettingGauge

Thistoolneeds itscuttingedgesettothecentreheightofthelatheThereareseveralwaystodothisbutoneoftheeasiestiswith a home-made height gaugeWhen starting out this is achickenandeggsituationyouneedtomakethegaugetosettheheightbutyoualsoneedatoolsetatthecorrectheighttomakethegaugeThesimplestwaytoovercomethisproblemistosetthelathe

tooltotheapproximatecentreheightandtakeacutacrossthefaceofthebarDependingonwhetherthereisapipremainingon theendof thebaryoushouldgetan ideahow farout thetoolheightisIfthereisnopipthismeansthetoolisoncorrectcentre height or too high A pipmeans the tool is too lowOfcourse you may have been lucky so try dropping the toolslightly until a pip remains You can then raise the tool a fewthouatatimeuntilthepipdisappearsThetoolshouldthenbeoncentreheight

Barwithnopiptooloncentre

Nowthatthetoolisatcentreheightyoucanmakeasimpleheight gauge Turn a piece of bar down to as close to frac12in(12mm)asyoucangetandleaveitinthelathechuckMeasurefromthetopofthecrossslidetothetopofthebarwithacheapheightgaugeLowertheheightgaugebyhalfthebardiameterTheheight

gaugeshouldbeexactlyonthelathecentrelineMakeanoteofthisdimensionWe now need to look at how to turn a bit of bar to an

accuratediameterWhenturningabartosayfrac12in(12mm)youneedtostartwithsomethingslightlylargerInthiscasethiswillbe⅝in(16mm)diametermaterialasthisisastandardsizeCutapieceofmaterialabout2in(50mm)longandputitinto

thechuckwithabout1in(25mm)stickingoutSkimtheoutsidedown to about 0510 thou or 1225mm which is 10 thou(025mm) above the size required (You should be aware thatmosthobbylathedialsremovetwicewhattheysayaonethoudivisionforexamplewillusuallytake2thoufromthediameterLargercommercial lathesaremuchmore likelytotakeoffonethoupergraduation)Nowtakesmallcutsuntilalmosttosizeusingpowerfeedif

you have it andmaking sure you knock the feed off before ithitsthechuckStopthelatheandwindthecarriagetothestart

of the bar Take another cut at the same setting andmake anoteofthediameterTakeanothershallowcutbutthistimegoonly about frac14in (6mm) along the bar knock the feed off andturn the lathe off Move the carriage towards the tailstock sothat you can measure the bar Continue making this cut andmeasureuntilthesizeiscorrectThenrunthetoolalongthefulllengthof the jobWindthecarriagebacktowardsthetailstockand take a finishing cut or two at the same setting ThediametershouldnowbetheexactsizerequiredIt is not difficult to turn accurately it just takes a little

patienceandpracticeThemoreturningyoudotheeasieryouwill find it is to hold accurate limits If you turn everythingaccuratelywhetheritneedstobeaccurateornotyouwillsoonlearntoturnwithinathouorsowithoutanyproblems

Measuringtheheightofthebarabovethecrossslide

Now we need to make a tool height setting gauge Cut alengthofbarjustoverthedimensionsyouwrotedownandfaceone end turn it round in the chuck and face the other endMeasurethelengthandfindouthowmuchyouhavetotakeoffit to give the dimension you want Put the bar back into thechuck and bring the tool up to the face of the bar Lock thecrossslideFacethebartolengthbyusingthetopslideindexmovingforwardsafewthouatatimeuntiltherequiredlength

is reached Younowhavea tool height settinggauge suitableforthefrontandreartoolsIf you have an inverted Vee bed lathe or if for any reason

youcanrsquotusetheheightgaugeflatonthebedyoucanputtheheightgaugeonaplateon topof the lathebedwhileyouaresettingthetoolheight

Settingtheheightgaugetothelathecentreheight

Settingtheheightofthetool

Usingthesettinggaugetosettheheightofthereartool

TurningtoaSpecificLengthandDiameter

Nowwewill turnabarwithastepon theendToensure thatthestep isthecorrect lengthwewilluseabedstopThiscanbe as simple as a block clamped to the lathe bed to stop thecarriage moving any further I use a simple home-made bedstopthatdoesallIrequireSetthebedstopthenmovethecarriageuntilittouchesthe

stop and lock it Wind the top slide so that the tool is justtouching the end of the bar and lock the carriage For thisexercise we will make the step 16mm long and 12mm indiameterWindthetopslidealong159mmWecannowroughout thestepateachendTurn theenddown toabout02mmabove the finisheddiameterbywinding thecarriagebackandforthYoucanusethe fine feedbutmakesureyouknockthefeed off before the carriage reaches the stop and finish up tothestopbyhandWindthetopslidealongtheremaining01mmto12mmandfinishthediametertosizeandlengthtakinglightcuts as previously Donrsquot forget to clean up the face of theshoulderyouhavejustturnedIfyouneedtouseabedstopatthetailstockendofthelathe

asimplemethodofdoingthisistouseabarplacedonthelathe

bed against the tailstock The bar acts as a stop when thecarriageiswoundbacktowardsthetailstockThistailstockendbed stop is useful when you are turning a groove in acomponentandyouneedstopssetatboth theheadstockandtailstockendsofthelathe

Ahome-madebedstop

TurningWorkontheOutsideoftheInsideJaws

Theoutsideoftheinside(drill)jawsareusefulforturninglargerdiameterwork that is too large to fit inside thedrill jawsThiswillmostoftenbe in the formofa flywheelcastingFlywheelswithsixspokesareidealforturninginathree-jawchuckasthespokes can fit between the chuck jaws Ideally you need totighten up the flywheel until it is tight but not so tight as todistorttherim

TurningasteponabarusingthestopThebarisheldinthethree-jawchuckandsupportedwiththetailstockcentre

Ausefultailstockendbackstopmethod

Holdingaflywheelinathree-jawchuck

Holdingaflywheelintheoutsidejaws

To ensure concentricity you should do as much work aspossibleonthecastingatthesametimeYoushouldbeabletoturntheoutsiderimofthecastingfacetherimfacethebossand drill bore and ream for the crankshaft all at the samesettingAllyouneedtodothenistofittheoutsidejawsreversethecastinginthechucktapitgentlybackontothestepsoftheoutsidejawsandfaceacrossthesecondsideoftherimandthehubUseabitofshimtoprotecttheflywheeldiameterItdoesnotmatter if the flywheel runs exactly true or not as you areonlyfacingitparallelandtowidthnotturninganydiametersto

size

UsingtheSoftJaws

Soft jaws are very useful when a component has to run deadtrue in the jaws for example when making something like agrindingspindlewhereconcentricityisimportantSoftjawslikelytobefoundinthehomeworkshoparesimple

rectangles of steel with the scroll and groove formed directlyintothesoftjawsAnothertypeofjawyoumaycomeacrosshasa grooved pattern in the main jaws that matches a similarpattern in theactualsoft jawsThesoft topsof these jawsareusually interchangeable They are more likely to be found onlarger chucks but you could make your own version for thesmallersizesofchuckifyouwishThemain use of soft jaws is for second operationwork for

examplewhenyouhaveturnedacomponentcomplete fromabitofbarandparteditoffNowyouneedtoholdthecomponenttruetofinishoffthesecondendYoucandothisbyboringoutthechuckjawstotheexactdiameteroftheworkpieceToborethesoft jawstheyshouldbetightened inthesame

direction as they will be tightened in use so that they areoperatingonthesamepartofthechuckscrolleverytimeIfyouhaveathincomponenttomachinefitthesoftjawstothechuckandtightenthejawsontoabitofbarheldinthechuckBesureto leaveenoughspace in frontof thebarsoyoucanbore thejawstofitthework

BoringsoftjawstofittheworkThejawsareclosedontoanoddmentofbartoturntheshallowregistersothatittakesthework

AlwaysusethesamechuckkeyholewhentighteningupthejawsThisappliestoanythingyoudowithaself-centringchuckStampacrossoracentrepopmarkagainstoneof the jaws IsuggestdoingthisnexttojawNo1butanyonewilldoaslongas you always use the samemarked hole Youmight as wellmarkallyourself-centringchucksinthesamemannerCarefullyborethejawstotheexactdiameteroftheworkto

be machined Try to get it exactly on size Undo the jawsslightly remove the bar and replace it with the workpiecewhichshouldnowrundeadtrueAusefulmodificationtothesoftjawsistodrillandtapahole

inthemiddleofthejawsandfitanAllenscrewtoeachholeIfyouwant toholda longbar in thesoft jaws it isnoweasy toboreallthewaythroughthejawsratherthanjustboringastepor part way through All you need to do now is find a disc ofmaterial to put into the chuck ensuring there is sufficientmaterialleftontheinsideedgesofthechuckjawstoborerightthroughtotakethebar

Holdthedisconthescrewheads ifnecessarydrillthediscbeforeboringBorerightthroughthediscandthejawsuntilyouarenearlytosizeatwhichpointyoucanborethroughthediscand test the resultingborewith theworkpieceMakesureyouclean the bore thoroughly before trying the workpiece sinceloose dust can make the hole seem smaller than it really isWhentheworkpieceenterstheborefinishboringrightthroughthe jawsgo througha coupleof timesat the samesetting totakeoutanyspringintheboringbarYoucannowremovethedisc clean the jaws and put the workpiece right through thechuckcheckingthatitrunsdeadtrueThisoperationmaysoundtimeconsumingforasingle item

but if you have several components to make it will save aconsiderable time on setting up each bar individually to runtrue

BoringsoftjawsusingaringThesoftjawshavethreeAllenscrewsthatarecloseddownontotheringwhileboring

TurningtheoutsideofthesoftjawsusingaringThesoftjawshavethreeAllenscrewsthatareopenedupontotheringwhileturning

NowthescrewsareinplacewecanworktheotherwayroundandholdcomponentsontheoutsideofthejawsTodothisyouwillneedaringofasuitablesizeontowhichyoucantightenthejawswith the jaw loading acting outwards so any componentyouputontheoutsideofthejawswillberunningconcentricallyThiswill be ideal for itemssuchas tractionenginewheel rimsandotherlargehollowortubularworkpiecesOne other use for soft jaws is to hold irregular-shaped

components Put a piece of bar into the soft jaws and bore aholeofanysizeand thencleanup theboreso thatallof thejawsare true Transfer the chuck to themillingmachine tableandclampitdownUseatestindicatortocheckthattheholeinthechuckistrueYou can now mill a nest to take any irregularly shaped

component confident that when the chuck is returned to thelatheitwillberunningtrue

Plungertypedialtestindicator

Levertypedialtestindicator

DialTestIndicators

Therearetwomaintypesofdialtestindicatortheplungertypedial test indicator as its name suggests works on a plungerprinciplewhilethelevertypedialtestindicatorhasastylusonthe end The lever stylus is usually ball-or pear-shaped and isfixedtothedialtestindicatorwithafrictionfitmeaningthatitcanbemovedupanddownontheendofthedialtestindicator

throughawidearctoputitintothebestpositionforuseThe plunger type dial indicator usually has a maximum

plungermovementoffrac12in (12mm)butplungermovementsofupto2in(50mm)areavailableTheplungertypedialindicatoris non-reversing and needs an adaptor to enable it to clockholes true Instead of a stylus it has an interchangeable endoften with a ball fitted various interchangeable ends areavailableoryoucanmakeyourownThe lever dial test indicator has a much smaller range of

travelarangeof0008in(02mm)isverycommonItisusuallyeither self-reversing (itmoveswhen in contact with theworkdependingonwhichwayitismoving)oritmaybereversedbyusinga lever on the sideof thedial test indicator both typesarequite commonSince the stylus isdelicate combinedwithitslimitedtravelrangeyoumustbeverycarefulnottobreakitAplungerdialindicatorcanbeusedasadirectreadoutofthe

travel and will be found to be very accurate Owing to therelativelylongtravelifyouwantedperhapstooffsetthecentreofabitofbar in the four-jawchuckby0125in (318mm) thiscanbedonebyturningthechuckbyhandandsettingthebaruntil the indicator travel shows 0250in (635mm) which is0125in (318mm) offset The lever dial test indicator is of nouseforgivingdirectreadingslikethisbutshouldbeusedasacomparatorwherethereadingtakenisforexamplezeroatallpointsofthetravelThedial test indicator is usuallymounted on amagnetic or

vacuum base but is sometimes fixed to a block that can beclampedtothelathemostoftenonthecrossslideSometimesthedialtestindicatorcomesasacompletekitincludingvariousmountingcomponents

Clockingtheendofacastinginafour-jawchuck

Four-jawChuck

To set thework up in an independent four-jaw chuckwe firstneed to know what part of the workpiece should be on thecentre If theworkpiece is a castingwemay have an outsidediameter or a hole that needs to run true in this case wewould put a dial test indicator onto the work and adjust thechuckalittleatatimeuntilthediameterrunstrueDonotturnthe chuck with the indicator in the hole Instead wind thecarriage forwards until the clock enters the hole and take areadingWind thecarriageback rotate thechuck90degreeswindthecarriageforwardandtakeanotherreadingAdjusttheworkinthechuckuntilitrunstrue

WhereacastingisstickingoutashereyoushouldtrytosupportthecastingwitharunningcentreThiswillhelptostopthecastingshiftinginthechuck

LatheCentreFinder

If there isnodiameterorholeyoumayhave tomarkout thecentreontheworkusingaheightgaugeandcentrepopitwithacentrepunchThenyoucanuseawobblerandatestindicatortosettheworktrueItwasoncepossibletogetalathecentrefinderconsistingof

a bar about 6in (150mm) long pointed at both ends with auniversaljointabout1in(25mm)fromthefrontendInusetheshortfrontendgoesinthecentrepopoftheworkinthechuckWhen you rotate the chuck by hand the pointed short endfollows the eccentricity of the centre hole which ismagnifiedaboutsixtimesatthetailstockendYouthenjusthavetoadjustthechuckuntilthetailstockendisrunningtrueatwhichpointthe centre in the work will also be running dead true I donrsquotknow anyone who makes these and second-hand ones areextremelyrare

Asimplehome-madecentrefinder

You can make a simple version of this that works well byusingamillingmachinepointedcentrefinderThisisaparallelbarwithaseparatemoveablepointedendThetwocomponentsare held together with a spring inside You need the pointededge finder a Morse taper parallel adaptor (the Morse tapershould fityour tailstock)aspringandashortstubofbar thatwillfitinsidethetaperedholderrsquosboretostopthespringgoingrightthroughPuttheshortstubofbarintothetaperinsertthespring follow up with the centre and put the Morse taperadaptorintothetailstockBringthetailstocktowardsthechuckuntil the centre of the centre finder is in the centre pop ThespringwillholditinplaceTousetheimprovisedcentrefinderput a dial test indicator onto the parallel part of the centrefinderrsquospointandrotatethechuckbyhandThepointwillrotateeccentricallyadjust thechuckuntil thecentre finderrsquospoint isrunningtrue

Usingascribingblockwithadialtestindicator

Move the tailstock along the bed until the point of thewobblerisinthecentrepopontheworkPutthetestindicatoronthefrontdiameterofthewobblerandadjustthechuckjawsuntilthewobblerisrunningtrueWhensettingupacastingorsomethingsimilarwherenotall

of the diameters are machined you should use the dial testindicator on diameters thatwill not bemachined such as theinsideofaflywheelrimWhenyouhaveturnedallthefinisheddiameters they should then be true with the unmachineddiametersSetting work in the four-jaw chuck depends on the

componenttobemachinedIfyouareusingroundmaterialyoucansetittoruntrueusingadialtestindicatorHoweverifyouaresettingaroughcastingthevariationofsizeandroughnessofthecastingsmaywellbeunsuitableforadialtestindicatorThere are alternativemethods of settingwork up in a four-

jawchuckespeciallyforcastingsOneofthesimplestmethodsis toholdasquarebar in the lathetoolholderandusethis tosetthejobtrueInuseyouwindthebaruptotheworkandsetthedial tozeroorotherwisemakeanoteofwhere it isWindthebaroutorawayfromtheworkTurnthechuck180degreesand wind the bar up against the work again You can

immediatelyseewhichwaythebarneedstomovesothatitisrunningtrueAdjustthecastinginthefour-jawchuckandmovethecastingtowardsthecentrepointRepeatuntilthecastingisrunning true This method is also useful if you are setting asquarebar to run true Justcheckeach faceof thesquarebarwiththebitofmetal

Settingacastingbyusingasquarebar

StickyPinMethod

An alternative the sticky pin method is especially suited tolocomotive wheels or flywheels An ordinary household pin ismounted in plasticine or Blu-tack perhaps stuck on the lathetool and is arranged to point to the inside diameter of thewheelor flywheel thearea that isnotmachinedbut is leftascastAdjustthecastinguntiltheunmachinedfaceisrunningastrueasyoucangetitandthewheelisreadytoturnThestickypinmethodisalsousefulforsettingupworkthathasachuckingspigot such as a locomotive smokebox door Just hold thechucking spigot in the four-jaw chuck and adjust the castinguntilitrunstrueontheoutsidediameterandthefrontface

Usingacommercialstickypintosetworktrue

Themethodsofcentringworkinthefour-jawchuckthathavebeen discussed are also suitable for setting work true on thefaceplate The next chapter looks at turning between centresandusingthefaceplate

6TurningbetweenCentresandFaceplateWork

Thischapterdealswithbasicturningbetweencentresandthenintroduces turning with the work mounted on the lathefaceplate

Headstockcentreanddriverplate(alsoknownasacatchplate)

TURNINGPLAINBARSBETWEENCENTRES

The most basic way of holding work for turning is between

centres Turning between centres is literally holding thecomponenttobemachinedbetweentwocentreseachofwhichhas a 60-degree included angle The headstock centre usuallygoes round with the headstockmandrel although some olderlatheshadanon-rotatingcentreandthedrivetotheworkwasbyapulleymountedontheworkThetailstockcentreisoftenafixedcentrethatdoesnotgoroundalthoughcentreswithballbearingscalledrunningcentresarereadilyavailable

Tailstockplaincentre

The component to be turned usually a shaft has a female60-degreecentreinbothendsthatisusedtosupporttheworkThe work can be turned round between centres so that bothends of the shaft can be machined Because the work ismountedbetweencentresbothendsoftheworkwillbetruetoeachother

Tailstockrunningcentreso-calledbecauseitrunsonballraces

CentringtheBar

FirstwehavetoputthecentresintoeachendofthebarIfthebarisshortsayuptoabout6inlongholdtheworkinthethree-jawchuckanduseacentredrillinthetailstockdrillchucktoputacentre intothebarAcentredrill isashortdrillwithasmallpilot on the end that has a 60-degree taper to the bodydiameterAbettermethodof centring thebar especially longbars is by using a three-jaw chuck and the fixed steady Thebarisheldinthethree-jawchuckwiththeotherendsupportedin the fixedsteadyand thecentre is formed in theendwithacentredrillAusefultoolthatcanbeusedtofindthecentreoftheshaftis

thecentresquarewhichisametalbladewithaVeeonitthatlocatesonthediameterofthebarMarkalineacrosstheendofthebarwitha scriber turn the centre square90degreesandthenscribeanotherlineWherethetwolinescrossisthecentreof thebar Tomake it easier to see the scribed linesblackenthe end of the bar with a permanent felt tip marker beforescribingCentrepunchthepointwherethetwolinescrossandput a 60-degree centre in each end of the bar using a centre

drill in a power drillHold thebar in a bench vicewhile doingthisPutacentredrillintothetailstockdrillchuckandinsertthebar in the three-jaw chuck Make sure the lathe is on a lowspeedabout300rpmwindthetailstockinandjustlightlycleanupthecentreholewiththecentredrilltotrueitupAnotherusefultooltofindthecentreofabarisabellcentre

punchThiscomprisesaconewithacentrepunchinthemiddleIn use place the bell end on the end of the bar and tap thecentrepunchwithahammertomarkthecentreTheendofthebar though needs to be reasonably square if using the bellpunchmethodThere are other similarmethods of centring bars but those

givenherewillbealltheturnerneedstolearn

Turningbetweencentres

Centringthebarusingthefixedsteady(Notethatthefrontclampisnormallydoneupwhileinuse)

Asimplecentresquare

Crosssectionofbellcentrepunch

MachiningtheBar

NowweneedtomountthebarbetweencentresThisissimplyamatterofputtingthebarbetweencentresandtighteningthetailstocksoitislightlypressingintothecentreintheendofthework To drive the work a carrier is fixed to the shaft andengagesapininacatchplatemountedonthelathemandrelAcatchplateissimplyablankdiscwithapinstickingouttodrivethecarrierthat isfittedtotheworkThecarrier isfittedtotheworkusinganAllenscreworboltTostopanymovementofthebarinrelationtothecatchplatethecarriercanbewiredtothecatchplatepinThiswill stop thecarrierand thework flappingaboutItisparticularlyimportanttostoptheworkfrommovingin relation to the catchplate when screwcutting betweencentres

Facingoffabarusingthehalfcentre

Nowthatthebarissafelymountedbetweencentreswecanstart turning it tosizeNormally the first thing todo is to facetheendsofthebartothefinishedlengthDecidewhichendofthebarhastheshallowercentreWewillmachinethisendfirstYouwillneedahalfcentreso-calledbecausealmosthalfofthecentre is missing This means the lathe tool can reach rightacrosstheendoftheworkwithouttouchingthehalfcentreWhenusinganyfixedcentreinthetailstockputabitofoilor

grease into the centre before use and top up as necessaryLightlywindthetailstockbarrelagainstthecentreandlockthebarrel so it canrsquotmoveSwitch the latheonandwind the toolacross to clean up the end Reverse the work and clean theotherendupat thesamesettingBothcentresshouldnowbethesamedepthMeasuretheoveralllengthofthebarTakethefinished length required from the overall measurement youhavejustmeasuredDividethisbytwoandthisishowmuchweneed to take off each end of the shaft so it finishes at therequiredlength

Askimmedbar

Ifyouhaveonechangethetailstockhalfcentretoarunningcentre if you donrsquot have a running centre change to a fixedcentreThehalfcentreshouldonlybeusedwhenfacingtheend

of the bar We will nowmachine the rest of the bar For thepurposeofthisexamplewewillassumethebarhasafinisheddiameter in themiddle with a step at each end First we willmachine the overall diameter to size To do this we need toskimthediameterandcheckthesizeTakeafinecutalongthebarusingthefinefeedifyouhaveoneMeasurebothendsofthebar Ifyouhavesetthelatheupcorrectly(seeChapter2)thebarshouldbeparallelIfitisnotadjustthetailstockbeforecontinuingAssumingthebarisparalleltakeanothercutortwosothatyouareabout01mmlargerthanthefinisheddiameterNowmove the tool in until almost at finished size and take alight cut about 10mm long along the bar Repeat this cut toensure the tool is notpushingoffMeasure thisdiameter youwill probablyhave towind the tailstockbarrel back toget themicrometerontotheendofthebarOnlymovethebarrelbackdo not slide the entire tailstock backMeasure the bar to findouthowmuchtoremovefromthediameterTakeanothershortcutandcheckforsizeWhenthebariscuttingtosizemachineall thewayalongYouwillprobablyhave to take twoor threecuts at the same setting until the bar ismachined to finishedsizeNowwewill turn the stepson theends Toensure that the

stepsare thecorrect lengthwewilluse thebedstopSet thebedstopthenwindthetopslidesothatthetoolisjusttouchingthe end of the bar For this exercise we will make the steps12mm long Wind the top slide along until the tool is justtouching the end of the turned bar Wind the top slide along119mmWecannowroughoutthestepateachendTurntheenddowntoabout02mmabovethefinisheddiameterYoucanusethefinefeedbutmakesureyouknockthefeedoffbeforethecarriagereachesthestopandfinishuptotheendbyhandRepeat for the other end Wind the top slide along theremaining01mmto12mmandfinisheachendinthesamewayasyoufinishedthemaindiameterDonrsquotforgettocleanupthefaceoftheshoulderyouhavejustturnedCongratulations you have just turned an accurate shaft

Donrsquotworryiftheshaftisatinybitundersizeyoucanprobably

makethematingholestofit

Thefinishedshaft

Usingachuckandarunningcentre

Usingthemethodsetoutaboveyoushouldnowbeabletoturn any shaft you require within the capacity of the lathe Avariationoftheabovemethodwheretheshaftissingle-endedistoholdoneendinthethree-orfour-jawchuckandsupporttheotherendwithacentreinthetailstock

Alargefaceplatesmalleronesareavailable

FACEPLATEWORK

Another basic way of holding work is on the faceplate Thismethod is used when the component is too large or isawkwardly shaped andwould be difficult to hold in a three-orfour-jaw chuck Usually the work is clamped directly onto thefaceplate often with a packing piece behind it to protect thefaceplateThefaceplateshouldbeflatandtruesothefirstthingtodo

whenyougetthelatheistocheckthefaceplatewithadialtestindicatorCarefullycleanthemandrelnoseandtheinternalholeinthefaceplateMakesurethemandrelcanturnfreelybyhandwith the lathe switched off and check that the face of thefaceplateisrunningtrueasclosetotheouteredgeasyoucanget If it is runningtrue runthetest indicatoracross the frontfaceofthefaceplatethisshouldbetrueaswellIfthefaceplateis running out itwill need to bemachined Put the lathe intobackgear if ithas it (topbackgearwillprobablybe fine)Youwill need a carbide-tipped tool ideallywith a small 45-degreechamferonthetipBringthetooluptothefaceplateand lockthe carriage Next you need to lightly face the faceplate right

acrossitsdiameterIfyouhaveapowercrossfeeditwillmakelight work of this but if not you can feed across by handFortunatelymost faceplateshavea series of rings on them toaid in setting up the work Machine the faceplate from theoutsidetothefirstringandstopforarest feedtothesecondring and so on until finished Depending upon how badly outyourfaceplateisyoumayhavetodothismorethanonceuntilit iscleanedupbutwhen it isdoneyouwill rarelyneedtodothisexerciseagain

Machiningaholeinablock

Asmentionedpreviously the ringsmachined on the faceplateareguidestohelpyousetuptheworkThiswilldoiftheworkisaroundcomponentbutweneedadifferentmethodiftheworkis square Take a block of metal for example that has beenmachinedalloverWewanttomachineaholeinit2infromoneedgeand1in fromanother edgeMarkout thepositionof theholeandcentrepunch it Put adeadcentre into the tailstockholdtheblockontothefaceplatebringthetailstockuptowardsthechuckandlockitWindthetailstockbarrelandcentreuptothe component and engage with the centre pop Lock thetailstock barrel Clamp the block to the faceplate using somepackingpiecesandfourclampsontheblockTheholeisnowoncentreandwecanmachineitinthecorrectplaceIf we need more than one hole placed accurately in the

componentwecanusetoolmakerrsquosbuttonstoensuretheholesare in the correct place Toolmakerrsquos buttons usually come insetsof fourOnebutton isusually longer than the rest soyoucanstillclockthediameterwhenitisclosetoanotherholeSetsare often available second-hand on eBaywhile they probablyhaveanobscureAmerican threadyoucanclamp themto theblock using your own BA or metric screws together with awasher

Settingupthefaceplateusingthetailstock

Asetoftoolmakerrsquosbuttons

Tofitthemtothecomponenttobeboredmarkoutdrillandtap holes in the approximate positions where the holes areneeded If you need a pair of parallel holes place thecomponentonasurfaceplate looselyfitthebuttonsandpushthem down onto a parallel or similar block of the correctthicknessandnipthescrewsupThespacershouldbesmallerthanrequiredbyhalfthediameterofabuttonIftheholesneedtobeacertaindistanceapartuseaspacer

of the correct size between the buttons (Remember tomake

thespacersmallerbyonediameterofthebutton)

Settingupacomponentusingtoolmakerrsquosbuttonstogetafixeddistancefromtheedgeofacomponent

TherearelotsofdifferentwaystosetthespacingofbuttonsItismainlyamatterofcommonsenseCastingsandflatcomponentscanbeboltedtothefaceplate

for machining A typical example of a flat component is aneccentric strap This type of component is usually made of acomponentthatiscutinhalfandboltedbacktogetherAholeisthenboredinitonthecentrelinetofittheeccentricThistypeofcomponentisoftendifficulttoholdinthelathechuckandisprone to distortion Castings are often too large to fit into alathechuckandso the faceplate iscalledon toundertake theworkAcastingcanoftenbebolteddirectlytothefaceplatetofacilitateeasymachining

Settingupacomponentusingtoolmakerrsquosbuttonstogetafixeddistancebetweenthecentresofacomponent

Work on the faceplate is often an odd shape or is set off

centreThiscauses it tobeunbalancedandasaconsequencethe lathemayvibratewhile thework is turningTocounteractthis tendency the faceplate should be counterbalanced byboltingweightsontoitAusefulsourceofweightsisthelathersquoschange wheels By bolting a change wheel or two onto thelightersideofthefaceplateyoucanbringthewholeassemblybackintobalanceAfterboltingthechangewheelsonspinthelathe by hand to check the balance The faceplate should notshowatendencytostopatoneparticularpointWhenyouarehappy that the faceplate is in balance the work and balanceweightsareboltedontightlyandsothattheworkdoesnotfoulthe lathewhen turnedbyhand switch themachine on in lowback gear to check for vibration Depending on what you areturning you should be able to run in top back gear or evenbottomdirectspeed

Asimpleclampsetisveryusefulwhenmachiningacastingonthefaceplate

TurningaFlywheel

Oneofthemainusesofafaceplateisturningalargediameteriron casting typically a flywheel or a locomotive wheel for asteamengineTheflywheelshouldbemountedsothattheinneredgeoftherimandtheouteredgeofthehubruntrueIfeitherofthemrunsoutitwouldbebetterthatthehubrunsoutasthe

rimwillbemorenoticeableonthefinishedengineClamp the flywheel down with some packing under the

spokessothatyoucanturnrightacrosstherimBecarefulthatyouclamptheflywheeltightenoughsothat itdoesnotmovebutnotsotightthatitdistortsRoughturn theoutsidediameterand facetherimusingthe

backgearUsingadirectdrivespeeddrillandborethecentrehole and either finish off with the boring tool or use a reamDonrsquot try reamingwithout boring the chances are that if youdotheholewillnotbetruewiththerimasthedrillprobablydidnotcutanaccurateholeDropdowntothetopbackgearspeedface the rim and turn the outside of the rim to the finisheddiameter Turn the flywheel over and finish the other face towidth

Astubarborsuitableforcentralizingalocomotivewheelorflywheel

TurningLocomotiveWheelFlanges

LocomotivewheelflangescanbeturnedonafaceplateYoucanpurchase blank end Morse taper arbors that fit into theheadstocktaperFitoneoftheseandturnaspigotonittotake

thewheel bore Thewheel bores should all be the same sizebut if they are different sizes machine the spigot to fit thelargestboremachinetheflangeonthatonethenmachinethespigotdowntofitthenextonemachinetheflangeandsoonIdeally the wheel bores should all be the same size but if

theyarenotproceedas followsSkimtheoutsidediameterofthe wheel flangemeasure and take it to the correct finishedsizeMovethelathetoolinbythedepthoftheflangeandturnthe tread Deal with all wheels like this machining all of theflangeoutsidediameterstothesamesizemovinginthecrossslidebythesameamounteachtimesothatallthetreadsendupthesamesize

UsingtheKeatsVeeangleplatetoturnaneccentriccomponent

KeatsVeeAnglePlate

TheKeatsVeeangleplate ismountedon the faceplateand isusedtoholdroundbarsquarebarandmiscellaneouscastingssuch as cylinders and steam chests The angle plate can bemountedanywhereonthefaceplateaslongasthelathecanbe

rotated safely and is in balance When spun by hand thefaceplateshouldnotshowatendencytostopatanyparticularplacewhenrununderpowerthelatheshouldnotvibrateAswellasholdingbarandcastingsforturningtheKeatsVee

angleplateisveryusefulformakingeccentriccomponentssuchastheeccentricsforasteamengineTo turn an eccentric use a test indicator to check that the

roundbarisrunningreasonablytrueWhenthisissatisfactoryyoucanturntheoutsidediameterofthebartofittheeccentricstrap (or component) including any step or groove requiredNextoffsettheKeatsVeeangleplatebytheamountyouwantthe eccentric lsquothrowrsquo to be Use the dial test indicator tomeasure the offset of the outside of the eccentric The offsetshouldbetwicethethrowYoucannowdrillboreandreamtheholeintheeccentricYounowhaveenoughbasic knowledge to carryout turning

between centres andwork accurately on the faceplate In thenext chapterwewill lookat holdingwork in a collet andonamandrel

7ColletsandMandrels

Thischapterexplainsallaboutholdingworkinacolletandhowyou canmake and use several different types of mandrel forworkholding

ERcollets

USINGCOLLETS

Quite a few different collet systems are to be found inworkshops Some are used for holding tools such as millingcutterssomeareusedforbarorworkpieceswhilesomemaybeusedwithbothbarandworkpiecesOne of the commonest is the ER collet which comes in

severaldifferent sizeseachhavingadifferent largediameterTheERcolletsystemallowsupto0039in(1mm)collapseofa

colletalthough in thesmaller sizesyoucanbuy thecollets in05mmincrementsA16mmcolletforexamplewillholdroundmaterialdownto15mmdiameterWhatevertheERcolletsizetheyallappear togodownto1mmminimumwhichwillclosedownto05mm

ERcolletadaptor

TherearemanytypesandsizesofERholderavailableAlltheusualMorse taper shank sizes are available and you can alsobuyvariousdiametersofextendedparallel shankholdersTheproblemwiththeseisthattheyaregreatforholdingtoolsthathave a short shank but because you need to use the holderwithadrawbaryoucanrsquotputlongbarstockrightthroughthemTo overcome this for lathe work you can also buy ER colletholdersdesignedtobefittedtoachuckbackplatethatyoucanmachine to suit your lathe so ensuring good concentricityBecause they donrsquot use a drawbar you can fit bar stock rightthroughandintotheheadstockmandrel

ERcolletadaptorfittedtoabackplateIalwaysleavebackplatesoversizesoIhavesomethingwithwhichtoclampthemdownwhenusedonamillordrill

When buying new and second-hand ER collets make surethey have the retaining groove near the nose end The older(andobsolete)EandEScollet typesdonothavetheretaininggrooveandarenotinter-changeableYouaremostlikelytofindEandEScolletsincludedwithasecond-handUnimatlatheDraw-in collets are usedwith a drawbar or collet tube The

drawbardrawsthecolletuptightbydrawingit intothelathersquosmandrelbyabar that runs through thecentreof themandreland screws into the centre of the collet Thismeans that youcannotputbarstockrightthroughthecolletToovercomethissome Morse taper collets use a hollow draw tube the collethaving an external thread tomatch the internal thread of thedrawtube

Draw-incollet

Special collets are made for the Myford ML7 Super 7 andML10 lathes These are Morse taper collets but rather thanhavingadrawbartheyareclosedwithanoseringthatfitsoveragrooveinthecolletThenoseringtightensthecolletintotheheadstockmandrelrsquos Morse taper It is extracted after use byundoing the nose piece which draws the collet out from theMorsetaperbythenosegrooveImperialandmetriccolletsareavailableuptofrac12in(12mm)diameterDead lengthcolletsareavailable that fit intoanattachment

usually fixed to the front of the lathersquosmandrel These colletsarecalleddeadlengthbecausetheydonotmovelongitudinallyunlike draw-in collets You are more likely to find collets likethesesecond-handratherthannew

BoxedsetofMyfordcollets

Deadlengthcollet

AvariationofthedeadlengthcolletistheCrawfordMultiborecolletThissystemhascolletsmadeofsegmentsheldtogetherbyspringsThecolletsareofvariablediameterandhavequitea

largeclosurerangeTheyaremorelikelytobefoundonalargercommercial lathe although you can get collets for smallermachinesWatchmakerrsquoscolletscanbeused inmost lathesbymaking

an adaptor for the headstock and a drawbar (or tube)Watchmakerrsquos collets are very accurate and can go down toverysmallsizesbuttheyhavelimiteduseinmostworkshopsYou can get a special watchmakerrsquos spindle for the EmcoUnimatlatheandthereisalsoaversionoftheCowellslathetheCW90thattakeswatchmakerrsquoscolletsFormost of thework carried out on the lathe youwill find

thatanERholder thatmountsontoachuckbackplate ismostuseful

Simpleexpandingmandrel

Simpleplainmandrel

MAKINGMANDRELS

There are several types of mandrel in common use inworkshops The most common is probably the expandingmandrelwhichcaneasilybemadeinanyworkshopInitsmostbasic form it is a bar turned to a size to fit the bore in theworkpieceItisthenthreadedwithataperedtapandslitat90degrees togive foursegmentswhichare thenexpandedbyascrewfittedintotheendofthemandrelAnother common mandrel is the tapered mandrel This is

usuallyalsquobetweencentresrsquomandrelandisoftenmadetotaperfromjustacoupleofthouovernominalsizetoacoupleofthouunder nominal size It is usually hardened and has a groundfinishTheworkpieceisheldinplacebybeingpushedontothemandreluntilitistightToremoveitjustpressitbackoutthewayitwentinWhereconcentricityisnotquitesoimportanttheworkpiece

canbeputonaplain turnedmandrelandtightenedupwithaboltandflatwasherExpandingmandrelsarealsomadecommerciallybutasyou

need a mandrel for each individual size of hole it can getexpensive if you need more than one or two different sizesCommercialmandrelscanbeobtainedwithMorsetapershanksto plug straight into the headstock Thismethod ensures thatthe mandrel should run dead true assuming both the Morsetapermandrel and theMorse taper in the headstock are bothcleanandfreefrommarksorswarfYou can also purchase Morse taper arbors with blank end

pieces from which to make your own mandrels First we willmake an expandingmandrel from a blank Morse taper arborYouwillneedtoturnthearbordowntofittheworkpieceboreIusually turn themandrelabout0010in (0025mm)oversize tostartwithandthenIdrillandtapthearborwithataperedtapThe drilled hole can go quite deep but the tapped hole onlyneedstogoinuntilthelockingbolt isabouthalfwaydownthelengthwheretheworkpiecewillsitPut the mandrel into the vice and cut along the mandrel

making four cuts around the circumferenceRetap thehole to

cleartheswarf fromthethreadandputthemandrelback intothe headstock taper Now you can lightly nip the screw up toexpandthemandrelslightlySkimthemandrel to finishedsizeuntil the workpiece will fit on without shake You can nowfurther tighten the screw so that the workpiece tightens ontothe mandrel When you slacken the screw the workpiece willcome off easily as you have skimmed it while it was slightlyexpandedYoucanmakeanexpandingmandrelfromabarheldin the three-or four-jawchuckorperhapsacollet inasimilarway Ifheld inachuck itmaynotgoback true ifyouneed touseitagainsoifpossibleyoushouldholdthearborinacolletFor aplainmandrel turn thediameter to fit theworkpiece

anddrillandtapforacapscreworaboltThereisnoneedtosplit this type ofmandrel You simply put the workpiece ontothemandrelandholditonwithaflatwasherAgainitdoesnotmatterwhetheryouuseabarinachuckorcolletorifyouusea Morse Taper blank arbor Arbors are very useful in theworkshop If youmake them fromMorse taper blanks or holdtheminacollettheycanbeusedoverandoveragain

8TaperTurningandLatheAccessories

Thischapterexplainshowyoucanturnataperusingatopslidetheuseoffixedandtravellingsteadiesandformtools

Turningataperwiththetopslide

TAPERTURNING

SometimesyouwillhavetoturnataperintheworkshopThatisa fairly easy jobWhat ismore difficult however is having toturnmatchingmaleandfemaletapers

Themethodyouaremostlikelytouseintheworkshopistoturn the two tapers with the top slide You should be able toturna taper longenough foraMorsetaperusingthismethodThemostimportantthingwhenturningtapersistoensurethatthe tool tip is at the exact centre height of the lathe This isbecause the taper will vary if the tool is not dead-on centreheightProbably the easiestmethod of turning aMorse taper is to

useadial test indicator toclocka lathecentreof therequiredMorse taper between centres The smaller end of the tapershouldbeatthetailstockendofthelatheThetopslideshouldbewoundalongthetaperby itshandwheelwhilethecarriageremainslockedThetopslideshouldbeadjustedangularlyuntilthedialtestindicatorreadszeroallthewayalongNowyoucanfinish turn the external Morse taper using an internal MorsetapersleeveasagaugetocheckthattheangleiscorrectTodothis make marks with a felt tipped pen along the taper andcheck that the test sleeve rubs evenly all the way along themaletaperAdjustifnecessaryuntilyouhaveaperfectfitToturnthematchingfemaletaperthelargeendofthetaper

willbeat the tailstockendand theboringbarwillbe invertedandcuttingon thebackof theholeDoing thismeans thataslongasbothofthetoolsareatcentreheightthetapersshouldmatchWecanusethemaletaperthathasjustbeenturnedasatestbarBoreoutthetaperverycarefullyyouwonrsquotneedtoremovemuchmaterial before the test taper goes too far intothe finishedbore Testwitha felt tippedpenuntil youhaveaperfectfitYou can turn any taper you need this way you are not

restrictedtoMorsetapersAnothermethodmostoftenusedforlongshallowtapersistouseataperturningattachmentTheseattachments are often available as extras on higher qualitylathes They comprise a slide mounted onto the back of thelathe Often the guide is dovetailed with a sliding blockattached to the cross slide to guide the tool on a taper ThedepthofcutisusuallyputonusingthetopslidesincethecrossslideisusuallydisconnectedfromthefeedscrewInthiswayit

isfreetomoveinandoutcontrolledbytheguide

Taperturningattachment

Settingthetopslidebyclockinganexistingtaper

Anothermethodweshalllookatfortaperturningistooffsetthe tailstock on its base This will make the work turnedbetween centres become tapered either large or small at thetailstockenddependingonwhichwaythe tailstock isoffset ifsettowardsthebackofthelathethediameterwillbelargerat

the tailstock end if the tailstock is moved to the front thetailstockendwill be smaller indiameter Theamountof taperthatcanbeturnedinthismannerislimitedsincetheheadstockandtailstockcentresareoutoflineThe final method of offsetting the workpiece is by using a

boringhead inthetailstockYouneedahome-madehardenedsolidcentrethatfitswheretheboringtoolwouldnormallygo(AsmallUnimatlathesizerunningcentremightbeideal)SettheboringheadsothetooltravelishorizontalYoucanthenoffsettheboringheadcentresocreatingataperThisisthesameassetting the tailstock over but you donrsquot have to realign thetailstockafterwards

Usingthefixedsteady

USINGFIXEDANDTRAVELLINGSTEADIES

The fixedsteady isusedmainly to turn theendofabaror tocentre a workpiece that is too large to fit through the chuckObviously bar stock should not protrude from the chuckmorethan is necessary to work on This is where the fixed steadycomesinThefixedsteadycanbesettothediameterofthebarsothattheendofthebarcanbemachinedsafely

Thesteadycanbesetusingachuckmountedonthistailstockadaptor

Travellingsteady

Settingthesteadybyusingachuckmountedonanadaptor

Onewaytosetthefixedsteadytosizeistoturnabitofbarin the chuck to the same size as the barwewant to use thesteadyonThenwecanmovethefixedsteadyalongthelathebedandfittheworkpieceintothechuckandinthesteadyTheendof thebar nearest to the tailstock shouldnowbe runningtrueandcanbeworkedonsafelyThebarcanbecentredrilledfacedorotherwiseworkedonAn alternative way to set the steady is to support the

tailstockendof thebarwitha threejawchuckmounted in thetailstockAdaptors to take the threejawchuckareavailableoryoucouldmakeyourownJustsupportthebaratbothendsinthethreejawchucksandsetthesteadyfingerstothebarThe fixed steadycanalsobeused to support tubes thatdo

nothaveanymaterialinthecentreThe fingers of the steady need to be lubricated regularly

while inuseThis iseasilydonebydrillinga smallhole in thetopfingerwithacountersinkinsidetheslottotakeoilThetravellingsteady ismostoftenusedwhenturningdown

small diameterbarsor screwcutting long slenderbars It boltsonto the front of the cross slide in line with the chuck and

travelsalongwhenthecrossslideismovedalongthelathebedWhen turning the travelling steady can either be set to thediameterofthebarbeforeturningandtoleadthetooloritcanbesettothefinisheddiameterrequiredandtofollowthetoolNormallythefingersaresetto leadtheturningtoolbut if thebarisroughforexampleifitisdentedorrustyitisbetterforthefingerstotrailtheturningtoolIfscrewcuttingthetravellingsteadyshould lead the toolso that itdoesnotdeflectorwearduetoaburrbeingthrownupbythescrewcuttingtoolSteadies will not be used very often but they are

indispensableontheoccasionswhentheyareneeded

Travellingsteadywithleadingfingers

Travellingsteadywithtrailingfingers

MAKINGASIMPLEFORMTOOL

Youmay often need to produce a particular shape such as aradiusonacomponentTheeasiestmethodtodothisiswithaformtoolAsanexamplewewillmakeasimpleformtooltocutahalfcircleonabarofbrassForaradiusof3mmforexampleweneedtoproducea formtoolusinga6mmdiameterdrillorreamFormaterialwewillusegaugeplateahighcarbonsteelthatcomesintheformofagroundflatbarApieceabout5mmthick and10mmwide is needed although the size is not thatimportantaslongasthegaugeplateisthickenoughtoabsorbanyturningstressesIdeallyweneedataperedreamerthatwillproduce a 6mm diameter hole somewhere along its lengthalthough you could use a parallel 6mm reamer a slot drill orendmillorevenastandardtwistdrillDrill a hole through the gauge plate and open up to 6mm

diameterAim togetagoodsurface finishon thesidesof thehole Hacksaw and file half the hole away to leave the shaperequired on the finish turned component Now we need to

harden the tool although ifweare justdoingacomponentortwoinbrasswecouldprobablygetawaywithouthardeningitHardeningissimpleenoughheattheworkingendofthetool

toredstopheatingandletthegaugeplaterestforacoupleofminutesThiswillgive thegaugeplateachance tochange itsinternalstructureReheattoredandquenchinatubofwaterThisshouldhardenthetoolAlthoughabitbrittle itshouldbefine for making a few components Stone the top of the tooluntil thecuttingedge issharp Ifnecessaryyoucanpolishtheinside of the radius that is going to do the cutting There areseveralmethodsyoucanuse includingapieceofwetanddrypaperaroundabitofbaraverysmallgrindingwheelcalledamounted point or a bit of round bar with fine valve grindingcompoundonitWhicheveryouuseaimforapolishedfinishasthe finish on the turned component is directly related to thefinish on the form tool You canmakeall sorts of simple formtools with gauge plate a typical example being a facing toolwitha30-degreechamfertofaceandchamfernuts

CopytemplatereadytouseMetal

MachiningfromaTemplate

MachiningfromaTemplate

YoucanmachineaprofilefromasimpletemplateThetemplatecanbecutfromgaugeplatewithafileormachinedbutitdoesnot need to be hardened The template could be used tomachinea large radius suchasa smokeboxdoor Inuse thetemplateismountedonablockonthelathebedandthecrossslide is kept in contact with the template by being pushedagainstthetemplatewithaballracefixedtothecrossslideInthenextchapterwewillbelookingatdrillingandreaming

9DrillingandReaming

ThischapterexplainshowtousedrillsandreamersinthelatheTherearemanydifferenttypesofdrillsandreamersTheyareessentialtomakingcomponentsinthelatheWewilllookatthevarioustypesandhowtochoosethespeedsandfeedsforusingthem

Thisdrillchuckrequiresachuckkey

TYPESOFDRILL

Drills are normally held either in the tailstock if they have aMorsetaperor inadrillchuckiftheyhaveaparallelshankA

drillchuckismountedonaMorsetapershankthatisusuallythelargestMorsetaperthatthetailstockwilltakeThelargestsizeof drill that will normally fit a drill chuck is frac12in (13mm) indiameter although larger chucks are available at a cost Thesmallest sizeofdrill thatafrac12in (13mm)drill chuckwill take isusually about 116in (15mm) This is because the larger drillchuck is incapableofclosingdownenoughto take thesmallersizesofdrillThismeanswewillprobablyneedtwodrillchucksoneforlargerdrillsandoneforsmallerdrills

Hand-tighteningdrillchuck

TherearetwomaintypesofdrillchuckOneistightenedbyusinga chuckkeywhichhasa small bevelgearbuilt on to itthatmates with the outer sleeve of the drill chuck itself Theother type is hand tightenedwhere the outer chuck sleeve isknurledtotightenthedrillthesleeveisturnedbyhandLargerdrillsabovefrac12in(13mm)usuallyhaveaNo1orNo2

MorsetapershankYoucangetMorsetapersleevestoconvertalargeMorsetoasmallerMorsetaperYoucanalsogetasmallMorsetolargeMorsetaperconverteraswell

Drillwithataperedshank

Some larger drills are also available with parallel shanksTheyaremadewithasteppeddownfrac12inparallelshankandarecalledblacksmithrsquosdrills

Blacksmithrsquosdrill

Themostusefuldrills in theworkshopcomeassetsofhighspeedsteeljobberdrillsinacaseThemostpopularsetcovers1mmto6mm increasingby01mmstepsAnotheruseful setcoversfrom6mmto10mmalsoincreasingby01mmstepsIfyouareintomodelengineeringasetofnumberdrillsfromNo1toNo60istoberecommended

Asetofmetricdrillscovering1ndash6mm

Drills are also available in different lengths Stub drills areshorter than standard jobber drills Several lengths of longseries drills are also available ranging from one and a halftimesthelengthofajobberdrilluptoseveraltimesthelength

Differentlengthsofdrills

Mostdrillshavetwoflutesbutcoredrillsarealsotobehadwith three four or evenmore flutes As their name suggeststhese are usually used for drilling out cored holes in castings

CoredrillsarenotnormallycapableofstartinganewholebutareusedforopeningupexistingholesAstandarddrillusuallyhasanincludedangleof118degrees

Stub drills and cobalt drills often have a 135 to 140 degreeangle for use on hardermaterials such as stainless steel andaircraftsteelsBack rakeondrills is oftenground radially Another typeof

pointhoweverhasfourfacetstothepointFour-facetdrillsaremuch better at starting a hole than a standard jobber drillwhich tends towanderunless followingacentrepoporcentredrill Four-facet drills also require less pressure to drill a holesincethepointisthinnerthanastandarddrillandtheyarefareasier to sharpen accurately by hand than standard jobberdrillsDormerdoarangeoffour-facetdrillscalledA002withatitaniumnitridecoating(TiN)andafour-facetpoint

Three-flutecoredrill

DormerA002four-facetdrillpoint

To drill an accurate sized hole requires two ormore stepsfirst youdrill the hole undersize (by perhapsfrac12mm) then youfollowthroughwithasizedrillThechancesaretheseconddrillwillcutdeadtosizeasitisonlycuttingasmallamountfromthediameter Obviously if you are drilling a large hole moreintermediatestepsmayberequiredSpeedsfordrillingarethesameasthosegivenforturninginthetableinChapter3

Setofcentredrills

REAMERS

There are several types of reamers available for use inworkshops again with either Morse taper or parallel shanksSomehavesizeparallelshankstheshankbeingthesamesizeas the reamer while others are availablewith shanks smallerthanthereamedsizeThereisalsothewaistedreamerwheretheshankisthesamesizeasthereamerthemiddleissmaller(waisted)andthecuttingendistheholesizeYoucanalsogetadjustablereamerswheretheendisexpandedbytheuseofascrewinthecuttingendofthereamer

Handreamerthefrontparthasaslighttaper

Straightshankmachinereamer

Waistedshankmachinereamer

Morsetapershankmachinereamer

Parallelreamersaredividedintotwotypesparallelmachinereamerswhere thecuttingdiameter is thesameallalong theream and hand reamers where the cutting end is slightlysmallerandtapersuptothefulldiameterWhen drilling a hole for reaming it is advisable to use the

two-holemethodfordrillingYouaremore likelytogetagoodsize hole prior to reaming For small reamers up to 04in(10mm) leave about 0012in (03mm) for the reamer toremoveForreamersuptofrac34in(19mm)leave0016in(04mm)and over frac12in (13mm) leave 0020in (05mm) For reamingspeedsuseabouta third toahalfof thedrillingspeed for thesamediameterFeedsshouldbefrom0002to0004in(0025ndash005mm)per toothper revMultiply the feedper toothby thenumberofteethtogivethefeedperrevolutionItisbesttouseneatcuttingoilformostmaterialsexceptfor

aluminiumforwhichparaffinshouldbeusedandplasticwhichrequirescompressedairorplainwaterYoushouldnotuseoilasacuttinglubricantforanytypeofplasticasitcanattackandordegradetheplastic

10BoringToolsandBoringHeads

Thischaptershowsyouhowtoboreholesinthelathewiththeworkheldinachuckmountedonthefaceplateorfixedtothelathecrossslide

TypicalHSSboringbar

DIFFERENTTYPESOFBORINGBARS

BoringaholetosizeisoneofthemostexactingjobsyoucandoinalatheItisrelativelyeasytoturnashafttofitaholebutitis much harder to bore an accurate hole to fit a shaft Ifpossibleyoushouldboretheholebeforeturningtheshaft

YouarelikelytocomeacrossHSSboringbarsorinsertedtipboringbarsBothhavetheirusesTheHSStoolisidealformostgeneralhole-boringjobsbuttheinsertedtiptoolisfarsuperiorfor materials such as cast iron The boring bar should be aslargeasyoucangetintotheholewhilestillallowingswarftoberemovedTheboringbarshouldonlyprotrudefarenoughtoenableitto

go completely through the bore Any more protrusion than isnecessarymay result in chatter or a dig in in the bore Thefront clearance on the boring bar tip should be as small aspossiblewithoutrubbingasstrengthisimportantBoringcanbeusedtofinishaholetosizeorsimplytotruea

holeupafterdrillingandpriortoreaming It isbesttoruntheboringtoolthroughtheholeusingafinefeedtothecarriageifyouhave the feedoptiononyour latheThe final finishingcutshouldbeputthroughtwoorthreetimesatthesamesettingtoeliminateanyspringinthetoolworkorlatheIftheholehasanintermittentcutthroughitsuchasacrossholetheholeisbestboredtosizeIt ispossible toborequite smallholes if youhave the right

tool Commercial lsquosmall holersquo boring tools are very expensivebut Ibuythemsecond-handwhenever Iseethemso Iusuallyhave a stock It is easy if time consuming to grind up smallboringbarsbuttheyareveryusefulespeciallywhenyouneedtotrueupasmallholepriortotappingorreamingEndmillsandslotdrillsmakeusefulboringtoolsAs longas

yougetthecuttingedgeoncentreheighttheywillboreaswellasaproperboringbarespeciallyinaluminiumYoucanmakesimplehome-madeboringtoolsbydrillingand

reamingaholetotakeaHSStoolbitintoasteelshankIdeallythe shank should be made of high tensile material or silversteelThetoolbitshouldbesecuredwithahightensilesocket-headedgrub screwor similar The tool bit caneitherprotrudefromthesideoftheboringbarforthroughholesorprotrudeatthe frontof theshankat45degrees ifyouareboringablindholeRoundboringbarscaneitherbeclampedintotheVeegroove

foundinsometoolholdersorheldinasplitsquareshankEithermethodissuitableespeciallyastheshankcanbeslidinoroutofthetoolholdertominimizeprotrusionSpeciallyshapedtoolbitscanbeusedtoundercuttheendof

the borewhen it needs to be screwcut and canrsquot be cut rightthrough Inserted HSS boring bars can also be ground up forundercuttingbeforescrewcuttingThereareseveralmethodsofcheckingaboreforaccuracyIf

youhavetoboretheholetofitanexistingcomponentperhapsaballraceyoucanuse theexistingcomponentasagaugeorturnupagaugeRoughout theborewithina few thouof thefinishedsize taking twoor threespringcutsUsea telescopicgaugeapairofcalliperswithamicrometeroradigitalverniertomeasuretheholeBorethestartoftheholebynomorethanonethouata timedonotgoright throughtheboreTest thefrontoftheboreifthegaugedoesnotgointotheborerunthetool right throughunderpower feedBoreout the frontof theholebyanotherthouchecktheboreandrepeatuntilthegaugejustgoesintothestartoftheholeFinishtheboreatthesamesetting checking that the gauge just enters Take a couple ofspringcutstoensuretheboreisparallelYoushouldnowhaveanaccuratelysizedholeThe trick to boring is to finish with very fine cuts Many

engineersdonotrecommendfinecutsbutIhaveneverhadaproblemaslongasthetoolissharp

Asetoftelescopicgaugesforcheckingaboreusedinconjunctionwithamicrometer

Checkingaborewithahome-madegaugeTheleadinisonethousmallerthantheborerequired

USINGABORINGHEADINTHELATHE

AnothermethodofboringacomponentinthelatheistoboltitdowntothecrossslideWhentheworkpieceisbolteddownandtheholeposition is linedupwith theheadstock youcanboretheholeintheworkpieceinseveralwaysFirst however you might need to put a hole into the

workpiece to clear the centre of the hole out of theway Youcandothisbyusingadrillinathree-orfour-jawchuck(smallerdrillscouldbeusedinadrillchuck)Startwithasmalldrillandworkupalmosttothefinishedsizeoftheholetobebored

Boringaholereadyforreaming

Toboretheholethefirstoptionistoholdaboringbarinthethree-jaw chuck This is a good basic method of boring aworkpieceonthecrossslideTheonlyawkwardbitisadjustingtheboringbarsothatasizeholeisboredThisisusuallydonebyanadjustingscrewpressingontothebackofthetipoppositethe cutting edge The tip itself is usually clamped by a grubscrewthroughthesideoftheboringbarHoweveryoucanuseaboringbarthatisafewthouundertherequiredsizeandfinishoffwithareamerA similar way that is easier to adjust is to use the same

boringbar in the independent four-jawchuckThen insteadofadjusting the tip in the boring bar you can adjust the entireboringbar inthefour-jawchuckThisasyoucanimaginewillbealoteasierthantryingtoadjustthetipintheboringbarThethirdmethodofboringworkonthecrossslideistousea

properboringheadThis iseasy toadjustas it isdesigned forthisverypurposeFinallyyoucouldusea lsquobetweencentresrsquoboringbarwhich

isheldbetweentheheadstockandtailstockcentresThisistheonly option when you are doing a long bore such as a largecylindercastingforalocomotiveortractionengine

Boringtheholeusingthefour-jawchuckmethod

Usingtheboringheadinthelathemandrel

Unlike when you are facing and boring a component in achuck you will not be able to face across the front of thecomponent (Boring heads with the ability to face across theworkareavailablebutareunlikelytobefoundintheamateurrsquosworkshop) Thismeans you will have to face across the workwith a flycutter in order to keep the face true with the boreFlycutters are available quite cheaply or you couldmake yourownandholditinthefour-jawchuck

Aflycuttersuitableforfacingthefrontofacomponentthathaspreviouslybeenboredonthe

crossslide

11KnurlingRadiusTurningandProductionMethods

This chapter explains how to use knurling tools and radiusturningtoolsaswellasusingbasicproductionmethods

KNURLING

Knurlingistheprocessofformingorimpressingapatternonapiece of metal often for the purpose of making a grip for apieceofequipmentsuchasaknobBothstraightanddiamondknurlscanbeproduceddependingonthetypeofknurlyouareusing Diamond knurling is usually done with two knurlingwheelsalthoughsingle-wheeldiamondknurlsareavailableKnurls are also available in fine medium and coarse sizes

although the size is relative fromdifferentmakers The speedfor knurling is usually about half of the turning speed for thesame diameter bar Normal knurling is of the male patternwheretheknurlingconsistsofraisedpyramidsFemaleknurlingismuchrarerandconsistsofdepressedpyramidsThere are threemain types of knurling tool but only two of

these are found in the average workshop The first type ofknurling tool is the so-called lsquocutrsquo knurling toolwhichactuallycutsaknurlratherthanpressestheknurlintotheworkThisisaspecialized tool more often used in industry and is veryexpensivesoitisnotfoundinmanyhomeworkshops

lsquoBumprsquoKnurling

The most common knurl is the single-or double-wheel knurlsometimes called a lsquobumprsquo knurling tool The wheels aremountedat the frontof the tool This typeof knurl is pressedintotheworkbyusingthecrossslideandcanproduceagoodqualityknurlHowever itdoesputveryheavypressureonthemandrelandlathebearings

Acommerciallyavailablestraddleknurlingtool

StraddleKnurling

Thebest typeofknurl foroccasionaluse is thestraddleknurlwhich has two knurling wheels that completely straddle theworkpieceThistypeofknurldoesnotputastrainonthelathebearings and so is preferred bymost lathe users (Two-wheelknurlingtoolsareavailablethatresemblestraddleknurlingtoolsbut they donrsquot open up to take anything more than smalldiameters relying on pressure at the side of the job like alsquobumprsquoknurl)To set the straddle knurl up wind the tool against a bit of

plateheldontothesideofthebarRemovetheplateandmovethetoolinbythethicknessoftheplatehalftheknurldiameterandhalfthebardiameterThiswillputthetoolontothecentrelineofthebar

Settingtheknurlingtool

In use set the knurling wheels to the centre as describedabove wind the knurls onto the outside diameter of the barwindtheknurlawayfromthebarandmovetheknurlingwheelsclosertogetherbytwicethedepthoftheknurlpatternSwitchthelatheonandwindthetoolbackontothecentrelineandthetool should start to form the knurl You can now traverse theknurlingtoolalongtheworkpieceto formtheknurl remembertousecuttingoilNote that theknurlsshouldhavechamferedsidesifyouaretraversingalongtheworkpieceYouneedtogodeepenoughsotheknurlisfullyformedbut

notsodeepastodeformtheknurlBecausetheknurlstraddlestheworktheknurlsstartoff independentlyandmaynotbe inalignment around the diameter Once you start moving theknurlingtoolbackwardsandforwardsalongtheworkhoweverthetoolshouldlineitselfupThismeansyoumayhavetoturndownorpartoffthebarwhereyoustartedtheknurlIfyougotoodeepespeciallyinaluminiumthewholedepth

ofknurlcouldgetdestroyedandevendropoff theparentbarThis is called flakingKnurling isnotadifficultprocessa littlepracticewillsoonhaveyouknurlinglikeaprofessionalengineer

Anaccomplishedbitofknurling

AformtoolcuttingaballTheinsetviewshowstheformtoolandafinishedball

RADIUSTURNING

Sometimesweneedtoformanexternalradiusontheendofabit of bar perhaps for a ball-shaped handle We can use asimple lathe attachment to do this Basically the attachment

consists of a short turning tool mounted onto a U-shapedcomponent that is arranged to pivot on another U-shapedcomponentheldinthelathetoolpostBy pivoting the attachment back and forth a radiuswill be

generatedForatrueradiusthepivotpointshouldbesetonthecentrelineofthebarTheradiusgeneratedwilldependonhowfarthetoolbitissetbackfromthecentrelineoftheworkpieceTosetthetoolupwindtheattachmentuptoaplateheldto

the sideof thebar youareworkingon remove theplate andwindinthewidthoftheplatehalfthewidthofthebarandthewidthofthefixturetothecentrelineofthepinThiswillputthepivotonthecentrelineThenyoucansetthetooltotheoutsidediameterofthebarThiswillproduceaballthesamediameterasthebarTo turnan internaldiameteruse the samemethodbut the

turning tool will need to pass through the centre of the pivotand out the other side You will be limited to shallowdepressionsratherthanlargesemicirclesbutthistechniquecanstillbeusefulonoccasionThealternativemethodof formingaball iswithaball form

tool

Astopbarblockforthecarriagestop

PRODUCTIONMETHODS

PRODUCTIONMETHODS

Foreaseofproductionthefirstthingyouneedtouseisabedstop (see Chapter 5) The chances are that you will need tomakeyourownTheoneIuseisveryversatileandconsistsofablockmountedatthefrontofthelatheheadstocktogetherwitharodtoactasthestopDependinguponwhatyouaredoingitmaybeusefultohave

morethanonestopbareachwithitsownseparatestopblockInusethebarisinsertedintothemainblockasfarasthestopblock(if fitted)andlockedinplaceThefirststopbarcouldbeusedto facetheworkpieceandthesecond(shorterbar)couldbe used to turn along the diameter while a third bar couldpositionthepartingofftoolAnalternativeadditiontothestopbarcouldbeawasher(orwashers)ofknownthicknessplacingthewasher(orwashers)onthebarwillextendthestoppositionbythethicknessofthewashersusedAusefultipistostampanumberonthestopblockssothat

eachone isnumberedYoucouldalso stamp the thicknessonthewasherssoyoudonrsquothavetokeepmeasuringthemandjustpickthemupinthecorrectorderItsavesalittletimeandhelpsavoiderrorsThe whole point about using a stop is the consistency of

positionwhichistransferredtotheaccuracyofthecomponentit gives Once you have learnt to use a stop youwill wonderhowyoumanagedwithoutitEvenforone-offcomponentsitwillsaveyoutimeForatypicalone-offsteppedshaftsetthestopsotheturning

tooljustfacesthebarandfaceoffMove the top slide along for the length of the turned step

requiredTurnthestepYounowhaveastepontheendofthebarofaknownlengthNofiddlingnomeasuringndashyouknowitiscorrectUsing the bed stop offers a simple way of doing repeat

turning of lengths and diameters in the lathe Stops are notlimited to production methods they are very useful formachiningone-offsaswell

A single stop bar will serve for much of the work you aredoingbutsometimesyouneedmorethanonestopTheanswerhereistousemorethanonestopbarinconjunctionwithastopblockEachbarhasitsownstopblockthatcanbetightenedupThenyoucaninterchangethestopbarsandeachbarcanbesettotherequiredlengthbyusingavernierorruleYoujustsetthetwostopblockstothedifferencerequiredandlockthestopbarintheholderasnormalWhenyouneedmorethanoneofeachitemitisveryeasyto

save time in theworkshop once the lathe is set up you canmake several items in quick succession A typical example ofthis type of production is a simple spacer Set a facing andchamferingtoolinonetoolholderapartingofftoolinanothertoolholderandadrillinthetailstockchuckThefacingtoolandparting off tool are in fixed positions to each other so it is asimplematter of drilling thehole facingoffwithone tool andparting off with the other As long as the gap between thepartingofftoolandthefacingtoolremainsconstantthespacerswill remain at the samewidth each time youmachine one ofthemTheeasywaytosetthethicknessofthewasheristofaceoff

theendofthebarbringthepartingofftooluptothefinishedface and lock the cross slide Wind the parting off tool backslightly so you can move the bar forward in the chuckMeasuring with the vernier calliperrsquos depth rod from therighthandfaceofthepartingofftoolbringthebaroutslightlylonger than is needed for the washer thickness Using thetailstock chuck drill the hole using a centre drill for the firstwashertoensurethedrill runstrueNowsetthefacingtool inpositionfaceoffthewasherandpartofffromthebarMeasurethe washer and adjust the facing tool either way so that thethicknessof thewasher iscorrectPull thebar fromthechuckslightlyfurtherthanthefacingtoolsothateachwashercanbefaced to lengthYoucanmakeasmanywashersasyouneedall of the same thickness The same applies to nuts and anyothercomponentthatneedstobeasetlengthIfmakingboltsor screws theprinciple is thesamebutyou

willneed to turndown thediameter tobe threadedThis timethedifferencebetweenthepartingofftoolandtheturningtoolisthethicknessoftheheadInordertofacetolengthhoweverawasher of a known sizemust be inserted between the stopblockandthecrossslideThiswasherwillbethelengthoftheturneddownportionofthecomponentIfyouwanttomakeabatchofcomponentsbutdonrsquotwantto

keepmovingorchangingtoolsyoucanmachinethebatchonestepata timedoingoneoperationoneachcomponentbeforedoing the next operation on all the components Repeat thisuntil the complete batch ends up as completed componentsYou have the added advantage that the components willprobablyallbethesameshapeandsizesomethingthatisnotalwayspossiblewhenmachiningeachcomponentindividuallyTo make a batch of components such as washers to the

samethicknessisquitesimpleSetupapartingtooltopartoffthe components and set up a facing tool to face thecomponentsThedifferenceinpositionbetweenthefacingtooland the parting toolwill be the thickness of thewashers Youcanadjustthethicknessofthewasherbymovingthefacingtoolbackwardsor forwardswith the topslide toadjust it The rearpartingofftooldoesnotmoveotherthantopartoffthewasher

Makingwasherstothesamelengthusingfixedpositiontools

TAILSTOCKTURRET

AnotherusefulaccessoryisthetailstockturretThisisarotatingheadthatisusuallysetbackatanangleItfitsintothetailstockof the lathe and has multiple stations to take different toolsoftenitwilltakefourfiveorsixtoolsThebenefitofthisisthatitcanhaveabarendstopacentredrilladrillacountersinkatapandadieoranycombinationthereofallsetupreadytousein sequence The tools normally fit into holes bored into theturretToavoidtoolsstickingouttoofar it isbesttousestubdrillsinsertedintoroundbarsthatfitintotheturret

Anindexingturretthatfitsdirectlyintothetailstockofthelathe

YoucaneitherdrillandtaptheroundbarsoruseLoctite tosecure the drill in the round bar You can also buy roundadaptorswithaJacobschucktapermachinedontheendtotakechucksAnothermethodoffittingchucksistodrillandtaptheround bar to take chucks with threaded extensions ThesechuckscanoftenberetrievedfrombrokenBlackampDeckertypedrillsDieholderscanslideonapieceofroundrodintheturretFor

smaller diameter threads you can stop the die from rotatingusing your hand There is no need to reverse the lathe whenthreading just stop it and spin the die off by hand the samegoes for taps For larger taps and dies you can use a shorttommybartostoprotationbutmakesurethatthetommybarpositionisclosertotheworkthantheendofanyofthedrillsorthetommybarwillsnapthedrillsifyouletgoofitorifthetapordiejamsupYoucanalsomakeorbuyarunningcentretofitintotheturrettosaveremovingitwhenyouneedtousealathecentreOnlydothiswithsmallorlightworknotheavybarsorfor largecutsWhenused inconjunctionwithagoodbedstop

system a tailstock turret becomes a very versatile productionfacilityTheturretcanbemademoreversatilebyfittingalever-feed

tailstockattachmentoracapstan-style feedattachmenttothetailstockturretEitheroftheseattachmentswillmaketheturretveryfastinoperation

Anindexingturretsetupwithastopandacentredrill

Standardlever-feedtailstock

SECONDOPERATIONWORK

SECONDOPERATIONWORK

Sometimes it is necessary to do second operation work on apart-machinedcomponentUsually thiswillbeon theoppositeend to the one already turned There are two main ways ofholding theworkpiece in the correct position for furtherworkthechuckbackstopandsoftchuckjawsThechuckbackstopisquitesimpletomakeItconsistsofa

draw-incolletapieceofplainbarforthestopabitofthreadedbar a nut and a top hat collar The collet goes into the lathemandrelandisdrawninbythethreadedbarThethreadedbargoesthroughthemandrelandislockedinplacebythenutandthe tophatcollarat the left-handendThe tophatcollar is toprotecttheendofthemandrelThestopbarfitsthecolletandispositionedsothattheworkislocatedattherightdepthinthechuckThismeansthateachcomponentput intothechuckupagainstthebackstopwillalwaysbeheldinthesameposition

Capstan-stylelever-feedtailstock

Adraw-inbackstop

Softjawswithhexagonsadded

The secondmethod is to hold the component in soft jawswhich are bored out to hold the component (see Chapter 5)ThismeansthecomponentshouldrundeadtrueandeachonewillbeheldinthesamepositionreadytobemachinedSoft jaws tend to be used for larger components while the

backstop ismore likely tobeused forbarworkYoucanboltextension pieces to soft jaws to hold larger diameters orextensions can be machined to make a nest to take largercomponentsWhensoft jawsarewornoutandfaceddowntoo

lowforfurtheruseyoucanboltapieceofhexagonbartoeachjawtogivethemanewleaseoflifeIfyouhaveabatchofthreadedcomponentstofinishonthe

second end you can screw them into a bit of bar held in thechuck If theyarehexagonbolts just tightenup lightlywithaspanneriftheyareroundheadandtheheadwillbemachinedlateryoucouldtightenanduntightenthemwithapairofpliersThe more production work you do the more varied the

methods you will learn and the quicker you will makecomponentstoahighstandardofaccuracyA sensitive drilling attachment can be very useful when

drillingwith tiny drills The feed is by hand which gives it itssensitivity The attachment can also be used for small tapswherethetravelisfairlyshort

Machiningscrewheadsbyholdingthescrewinathreadedmandrel

Asensitivedrillingattachmentthatfitsintothe

tailstockchuck

ThisVeeattachmentisusedforcrossdrillingandcanbeusedintheheadstockorthetailstockofthelathedependingonthelengthofthebartobecrossdrilled

ThisisarevolvingtaperforthetailstockIfyoufitadrillchucktoityoucanuseitasarunningsupportforsmallbarwhereacentreisnotpermissible

12TapsDiesandScrewcutting

Thischaptershowshowtousetapsanddiestocutinternalandexternal threads in the lathe Italsoexplainshowyoucansetupasimplegeartrainandcutascrewthreadwiththehelpofascrewcuttingdialindicator

Atypicaldie

CUTTINGTHREADS

Threadcuttingeither internalorexternal isan importantpartoflearningtousealatheThepurposeofathreadisusuallysothatyouareabletoholdpartstogetheralthoughotherusesforthreadssuchasleadscrewsandfeedscrewsformachinetoolsareoftencalledfor

Safetyhasalreadybeencoveredindepth(seeChapter2)butafewextrawordsonsafetywhenthreadcuttingarecalledforWhen tapping a hole or threading a bar from the tailstock atailstocktapordieholderisoftenusedForthesmallerthreadstheholdershaveaknurledbodyandrotationcanbestoppedbysimplyholdingthebodyoftheholderinyourhandAslongasyoukeepyourhandawayfromthechuckandany

sharp lathe tools on the cross slide you should be fine (ifpossible remove either the tool holder or the tool itself )Providedthereisnothingtocatchorsquashyourhandonyoucan hold the knurled tap or die holder in your handwhile thelathe is running slowly under power and releasing the holderwhen the full length of the thread is cut or the pressurebecomes too great for you to stop the rotation (By slowly Imeaninveryslowbackgear)For largerthreadshoweveratommybarwilloftenneedto

beusedtostopthetapordieholderfromrotatingWhenusingthe tommy bar to prevent rotation do not under anycircumstances use the lathe under power Instead switch themachinerightoffandunplugit ifpossibleTurnthetapordieholdingthetommybarwiththerighthandandstopthechuckfromrotatingwiththelefthandThere are already many published charts providing thread

data covering such factors as tapping hole sizes minimummaximum and effective diameters as well as pitches andthreadsperinchIwillnotbeprovidingthemherebutwishtopoint out that tapping size drills can vary with the materialbeingcutWhenIamtappingsmallsizes instainlesssteel forexampleIusuallydrillthehole0004in(01mm)largerthanthefigurestated in thechartThisway Iam less likely tobreakatapinthehole

HSSorCarbonSteel

TapsanddiesareusuallymadefromcarbonsteelorHSSHSStapsanddiestendtoremainsharpformuchlongerthancarbonsteeltapsbutcarbonsteelisusuallycheaperNewcarbonsteel

tapsanddieswillprobablybefineforsmallerholesandsoftermaterials but wherever possible HSS should be your firstchoice Second-hand taps and dies are sometimes availablefromtoolshopsoroneBaybutinmyexperiencetheyareoftenbluntandnotworthbotheringwith

Lubricants

Whether tapping threading with a die or screwcutting it isnormallyessentialtousealubricantevenonbrassForbrassaluminium and bronze kerosene (paraffin) or white spirit isgenerallyusedandcanwithadvantagehaveasmallamountofcuttingoiladdedFor steel and stainless steel amodernpaste-based tapping

compound or cutting oil should be used This can also beappliedtocopperthismetalcanbestickybuttakeiteasyandall should gowell I also use paste or cutting oil on cast ironAlthoughmostrecommendationsaretocutcastirondryIhavefoundalubricanttobeveryhelpful

Screwthreadpitchgauge

ThreadGauges

When following a published design you will probably use thethread sizes as recommended by the designer If you are

making a thread to match an existing thread however youneedtofigureoutwhattheexistingthreadisThisiseasiesttodoonanexternalthreadIfyouhaveonlythenuttrytofindaboltthatwillfititandusethattocheckthethreadIfyoucanrsquotfindamatchingboltandtheholeinthenutisbigenoughyoucouldtrypressingabitofplasticineintotheinternalthreadandmeasuringthatTomeasuretheexternalthreadweneedtodeterminethree

thingsusingathreadpitchgauge theoutsidediameterof thethread the pitch of the thread and the thread angle Thesethree checks will probably be sufficient to decide what thethreadactuallyisBritish threads such as British Standard Fine and British

Standard Whitworth and also the Model Engineer threadsystemhaveanangleof55degreesAmerican threads such as UNF (Unified Fine) UNC (Unified

Coarse) UNEF (Unified Extra Fine) ANF (American NationalFine)ANC(AmericanNationalCoarse)are60degreesasisISOmetricUnusually theBritishStandardCycle thread is also60degreesThe other thread youmight come across is the BA (British

Association)threadThishasathreadangleof47frac12degreesandismetricbasedThelargestBAthreadis0BAwhichhasa6mmdiameterwith a 1mmpitch TheBA series godown to 22BAbutinpracticeyouareunlikelytocomeacrossanythingsmallerthanabout14BA

TAPS

TappingistheprocessofcuttinganinternalthreadwithatapFirst a hole is centre drilled and drilled in the workpiece Irecommend that you give the top of the hole a 90-degreecountersinktogivealead-intothetapandalsotostopthetapfromthrowingupaburrontothefaceofthework

Setofhandtaps

TypesofTap

The many types of tap can be divided into hand taps andmachinetapsHandtapsarenormallyheldinatapwrenchbutcan be held in the lathersquos tailstock chuck or a purpose-madetailstocktapholder

Close-upofahandsecondtap

WhentappingbyhandstartthetapuntilitstartstobiteandgiveitanextraturnorsoReversethedirectionofthetapforaturn to break the chip Continue forward for a couple of turnsand then reverseasbeforeContinue todepthor through theworkpiece by continually tapping a couple of turns reversingandcontinuingforwardThisshouldclearthechipsandpreventthetapfrombreakingIfthetapgetshardtoturntakeitrightoutoftheholetoclearanyswarfaddsomemorelubricantandcontinuetappingA set of hand taps will normally comprise a taper tap a

secondtapandaplugtapUsuallyyouwillstartaholewithataper tap This is a tap where the outside of the thread isreducedtowardsthepointbygrindingitonataperThistypeoftap can be used to start the hole but if the hole goes rightthrough the work it may be possible to screw the tap rightthroughtheholesoformingafullthreadrightthroughIfthetapertapistooshortorifyouaretappingablindhole

youneedtofollowthetapertapwiththesecondtapwhichhasmuch lessofa taper In fact itonlytapersrightat thestartofthetapTheplugtapisfinallyusedusuallytofinishoffablindhole

Theplugtaphasnotaperonitjustashortlead-inontheendBetween the three you should be able to tap themajority ofholesintheworkshopWhentappingblindholesitisbesttoworkoutthedepthand

fromtherethenumberofturnsneededforthetaptoreachthebottomoftheholeAsanexamplesaytheholeis9mmdeeptothepointThe tapenters2mminto theholebeforestarting tocutSo9mmless2mmgives7mmThepitchofthetapis05mm7mmdividedby05equals14sothenumberofturnstothebottomoftheholeis14Inpractice12or13turnswillbethemaximumneededWhen tapping blind holes make sure that all swarf is

removedfromthebottomoftheholebeforestartingtotap

Selectionoftapholders

HoldingTaps

TherearetwomaintypesoftapwrenchthehandtapwrenchwhichisdesignedtobeheldwithbothhandsandtheTeetypetapwrenchwhichoncestartedcanoftenbeusedone-handedTapsusuallyhaveeitheracentreholedrilledintheshankor

theshankisgroundtoapointThismeanswecansupportthetapfromthetailstockeitherbyusingalathecentreorbyabitofbarinthetailstockchuckwithafemalecentreinitTeetypetapwrenchesoftenhaveafemalecentreintheendandcanbesupported on a running centreWhen the tap is supported bythe tailstock at one end and the hole in theworkpiece at the

otheritmustbeinlinewiththeholeintheworkpiece

Machinetap

MachineTaps

Themaintwotypesofmachinetaparethespiralpointandthespiral flute The spiral point pushes swarf downwards throughthe hole while the spiral flute pulls the swarf out of the holeSpiralflutetapsaremuchweakerthanspiralpointtapsandintheory should not be used for tapping by hand However inpractice you can often get away with hand tapping using aspiralpointtapifyouareverycarefulIneithercasethetapisdesigned for continuous rotation swarf being automaticallycleared so the regular reversal as with a hand tap is notnecessaryIf you are careful you can probably get away with using a

hand tap under power but only do this with a hand-held tapholderwhereyoucanquicklyletgoifthetapstartstostickYou can also getmachine taps thatwill cut a thread under

powerbyscrewingthroughthejobwithoutstopping

Spiralflutetap

SpeedsforTapping

Tappingspeedsshouldbe low lowbackgearspeedshouldbefineWhenyouhavetappedtheholetodepthorrightthroughtheworkpiecestopthelatheandspinthetapoutbyhandThiswillbequickerthanreversingthelathe

ThreadingfromtheTailstock

For small taps you can use the sensitive drilling attachment(seeChapter11)orifthetapislargeryoucoulduseaslidingtapholderThiscanbeassimpleasachuckmountedonataperat one endwith a parallel hole through the chuck shank ThechuckthenslidesonabarheldinthemaintailstockchuckForlargetapsyoucanuseatommybartostopthetapholderfromturningbutthetommybarshouldnotbesolongastofoulthelathebedoranyotherpartofthemachineifyouhavetoletgoInfactitisfarsaferifyoudonotusethetommybartothreadunderpower

DIES

Dies also come in carbon steel andHSS versions The outsidediameterofadieoftenvarieswiththesizeofthethreadbeingcutalthoughthediameterwillbetooneofasetstandardDiesusually have themakerrsquos name and the thread details on thefrontof thedieThis is theside that ispresented to theworkThediewill havea short lead-in if this isnot requiredon thefinishedthreadyoucanreversethedieanditwillcleanuptoashoulder

SlidingtapholderSlidingdieholdersarealsoavailable

When cutting a thread especially a small one it pays tomaketheinitiallengthofthreadlongerthanthatrequiredThisissoyouhaveabitat thefronttoplaywithtogetthethreadright Then you can part off the excess length leaving a goodthreadoftherequiredlengthDies are usually split so you can adjust them to cut a size

threadIdeallyyoushouldhaveadieholderforeachdiesoyoucansetthedietocutsizewithouthavingtoresetiteverytimeyouchangethedieThedieshouldbesetsothatitcutsasizethreadinonepassDie nuts are often hexagonal in shape They are used to

cleanupanexistingthreadthat isdamagednot tocutanewthreadfromscratchFor each thread you are going to cut you should make a

home-madegaugetappedwithyourowntapWhenyoucutthethreadanditfitsthisgaugeyoushouldthenhaveagoodbutnottightorloosethreadYoushoulduseatailstockdieholderwithaslidingbodywhen

threadingfromthetailstockasthiswillholdthedietruetothethreadIdeally the tailstock die holder should be knurled and also

haveatommybarholeforeaseofuseThe speed for threading with a die in the lathe should be

quitelowamaximumof60rpmshouldbefineformostjobs

SCREWCUTTINGATHREAD

Whilecuttingathreadwithtapsanddiesisperfectlyadequatefor most applications the ability to cut an accurate screwthreadbyusingthelatheisaveryusefulfacilitytohaveIfthethread is large or non-standard taps and dies may not beavailable or they may be so expensive as to be out of thequestionforuseintheamateurrsquosworkshopVariouspitchesofthreadcanbecutbythesimpleexpedient

of changing the configuration of the change gears or alteringtheleversonthescrewcuttinggearboxifoneisfittedWewillconcentrate on a lathe with change gears if you have ascrewcutting gearbox please refer to the manufacturerrsquoshandbookMost lathes that youwill comeacross are likely to have an

imperialpitch leadscrewThiswillbeapitchofsomany teethper inch (TPI) Typically this will be 4 or 8 TPI although otherpitchesareavailableForourexamplewewillbeusingalathewithan8TPI leadscrewandasetofchangewheelscomprisingthefollowingnumbersofteeth2times202530353840455055606570and75

SETTINGUPTHECHANGEGEARS

Letrsquostakeatypicalthreadpitchof20TPIForeveryturnofthemandrel the leadscrew needs to move forward 120in Thismeans we have to set the change gears so the mandrel toleadscrewturnratio iscorrect Inpracticethemandrelgear islikely tobe20 teethand this is unlikely to change nomatterwhat thread we are cutting This means we will change theleadscrew gear which has to have the correct ratio to themandrelTheTPIwewishtocutis20usingaleadscrewwithapitchof

8TPI20dividedby8givesusaratioof251Thismeansthatthe mandrel gear needs to rotate at 25 times the leadscrewgearAsthemandrelhas20teeththeleadscrewgearneedstobe25times20teethwhichisa50toothgearInpracticea20toothgearanda50toothgearmaybetoosmalltotransferthedrive from the mandrel to the leadscrew and intermediategear(s)willneedtobeusedThese gears are called idler gears and they can have any

number of teeth Youmay think these idler gears change theratio of the mandrel to the leadscrew but they do not Theysimply transfer the drive from the mandrel gear to theleadscrew and the ratio stays the same This concept can behardtograspsoIwilltrytoexplainitsimplySay the mandrel gear does one turn This makes the idler

gearorgearsmoveexactly20teethandthisinturnmovestheleadscrewgearexactly20teethAsyoucanseetheratiodoesnotaltertheleadscrewgearmoves20teethforevery20teeththemandrelgearmovesandtheratiostaysthesameThistypeofset-upisknownasasimplegeartrain

Simplegeartrain

Compoundgeartrain

Letuslookatanothercommonthreadpitch32TPITheratioofleadscrewtoTPIis41(8times4=32)Sotheleadscrewgearneeds to be themandrel gear 20 teeth times 4 = 80 teethLookingattheavailablegearswedonrsquothavean80toothgearThismeanswewillhavetouseadifferentmethodtogetour41ratioWithamandrelgearof20teethwecouldusea40toothto

give us a ratio of 21 We are now halfway there but needanotherpairofgearswitha21ratioWedohavea30anda60

toothgearsothiswouldgiveusoursecond21ratioWecouldnot set these gears up as in the previous example howeversince the two intermediate gears would just act as idlers andtheratiowouldbe2150percentoutfromwhatisrequiredWhatwewouldhavetodoismountthe40toothandthe30

tooth gears on the same spindle so they rotate at the samespeedaseachother(The20toothgearmustdrivethe40toothgearandthe30toothgearmustdrivethe60toothgearinthisorder)Thiswouldgiveusthecorrect41ratiothatweneedAswehavemountedtwogearsononespindlethisisknownasasinglecompoundgeartrainDependingonyourlatheyoumayneedanidlergearbetweenthe30toothgearandthe60toothgearAgainthiswillnotalterthegearratiosYou can also have double compoundgear trainswhere two

lots of gears are mounted together on two spindles This istaking us into complicated territory however and I will referreaders to the screwcutting chart provided for their particularlathe Ifyour lathedoesnotcomewithascrewcuttingchartasearchon the Internet should findone that you candownloadandprintoutThemost likely application of double compound gear trains

would be to cutmetric threads with an imperial leadscrew orimperialthreadsover60TPII have tried to keep this explanation of setting up

screwcutting gears simple and the maths to a minimum Theexplanationgiventogetherwiththescrewcuttingchartforyourlatheshouldbemorethansufficienttogetyougoing

ExternalscrewthreadtoolmadefromaCoventry

diechaser

CUTTINGTHETHREAD

The speed for screwcutting should be about mid-back gear ifyouhaveitpreferablysomewherearound30ndash40rpmatmostTherearetwomainmethodsofscrewcuttinginthelatheThe

firstoneinvolvesthetopslidesetparalleltotheworkandintheothermethodthetopslideissetonanangletothework

Externalsinglepointscrewthreadtoolsettinggauge

Cuttinga20TPIThreadwiththeTopSlideParallel

For a 20 TPI Whitworth thread the pitch is 0050in and thethreaddepthisaconstant064ofthepitchsothethreaddepthis 0050 times 064 = 0032in This is the depth the cross slideshouldbewoundinWhilethedepthofthreadis0032inyoualsoneedtomove

the top slide forwardat eachpass Fora standardVee threadthisneedstobehalfthein-feedofthescrewcuttingtoolsoyoumovethecrossslideinby0010inandmovethetopslidealongbyhalfthis0005in

Cuttingascrewthreadwiththetopslidesetparalleltothelathe

Cuttingascrewthreadwiththetopslidesetatanangletothelathe

Theendresulta20TPIfinishedthreadbeforetidyinguptheendandundercutting

Cuttinga20TPIThreadwiththeTopSlideatanAngle

This angle will vary according to the thread being cut but itshouldbeabout1degree less thanhalf the includedangleofthethreadforaWhitworththreadof55degreesforexampletheangleshouldbehalfof55degreesminus1degreegiving265degreesNotethattheangleistakenwiththetopslidesetat90degreestotheworkWiththetopslidehandlefacingyou(at90degreestohowit isnormallyused)rotatethetopslidethe required number of degrees (265) to the right Beginnersoften rotate the top slide 265 degrees to the left from thenormalpositionwhichwouldgivean included threadangleof127degreesThisisclearlywrongBecausethetopslideissetonanangleyouwillneedtofeed

thetopslideinfurtherthanifthetopslideissetparalleltothelatheYoucan findthe increaseddepthof threadbyusingthefollowingformula

c=bcosineofA

whereAistheanglecalculatedathalftheincludedthreadangleminus1degreegiving265degreesb is thedepthof thread(forWhitworththreadsthisis064timesthepitch)andcisthecalculatedangulardepthofthreadFor a 20 TPIWhitworth thread the pitch is 0050in and the

threaddepthisaconstant064ofthepitchsothethreaddepthis0050times064=0032inThecompensateddepthofthreadisthen0032individedbythecosineof265degrees=00357

UsingtheThreadCuttingIndicator

With an 8 TPI leadscrew if the thread being cut has an evennumber of threads the leadscrew can be engaged at anypositionof the threadcuttingdial indicator If the thread isanoddnumberyoushouldusethesamenumberoranyalternatenumberthatisoneorthreetwoorfourForthreadswithahalfpitch always use the same number For metric threads orpeculiar numbers do not disengage the clasp nuts withdrawthescrewcuttingtoolandreversethemotoruntilthetoolgoesback to the start If the thread is an exact multiple of theleadscrewtheclaspnutscanbeengagedatanypositionIfindoubtalwaysengageatthesamenumberoneIttakes

verylittletimetotraversetheextradistancerequiredFor leadscrews other than 8 TPI please refer to your lathe

manual

AcknowledgementsandUsefulContacts

I would like to thankMy TimeMedia Ltd (Publishers ofModelEngineer and Model Engineersrsquo Workshop) Ken Wilson TonyJeffreeandTranswavePowerCapacitorsLtdfortheuseoftheirphotographs

USEFULCONTACTS

UnitedKingdom

ArcEuroTradeLtd10ArchdaleStreetSystonLeicesterLE71NATelephone01162695693Fax01162605805EmailinformationarceurotradecoukhttpwwwarceurotradecoukSuppliersofmachinetoolsandaccessories

ChesterMachineToolsHawardenIndustrialParkHawardenChesterCH53PZTelephone01244531631EmailsaleschestermachinetoolscomhttpwwwchestermachinetoolscomSuppliersofmachinetoolsandaccessories

CowellsSmallMachineToolsLtdTendringRoadLittleBentleyColchesterEssexCO78SH

ThelaterML7RandSuper7modelswerefittedwithaclutchasstandardThissaveswearandtearontheelectricalcomponentsandthemotorTheyalsohadmorespeedsLaterversionsoftheSuper7canbefoundwithapowercrossfeedTheillustrationshowstheprototypeSuper7latheagainithasbeenrebuilttofactorystandardsbyMyfordLtd

TheAtoZofalathe(A)Changewheelguard(B)Countershaftpulleyguard(C)Drivebeltguard(D)Countershaft(E)Belttensionlever(F)

Oiler(G)Motor(H)Tumblergearoperatinglever(I)Headstock(J)Backgearoperatinglever(K)Mandrelnose(L)Left-handleadscrewbearing(M)Leadscrew(N)Halfnutoperatinglever(O)Toolclamp(P)Topslide(Q)Crossslide(R)Saddle(S)Apron(T)Carriagehandwheel(U)Screwthreadindicator(V)Lathebed(W)Rack(X)Tailstock(Y)Tailstockhandwheel(Z)Right-handleadscrewbearing

AnearlyMyfordlatheAlthoughverybasicitcandoalotofusefulworkintheworkshopespeciallyiftimeisspentonmakingafewsimpleaccessories

This book will show you how to use the lathe safely andeffectively in your workshop but first you should ensure thatyou are familiar with the main parts of the lathe and theirterminologywhichmaybefoundonpage9Chapter1ofthisbookisaboutchoosingalathewhatsizeof

lathe to buy the different types available desirable featuresandwhetheryoushouldbuyneworsecond-handChapter 2 covers installing a lathe how to lubricate it and

maintain it in good condition and advice on general safety inyourworkshopwithparticularemphasisonhowtousea lathesafelyChapter3will lookatthematerials fromwhichcuttingtools

aremadeaswellastheirbasicshapeandgeometryThenwe

willlookatselectingsuitablespeedsandfeedsChapter 4 dealswith sharpening lathe tools andhow to set

themupinthelatheChapter 5 covers the different types of chucks how to use

themandsetworkupaccuratelyinthemChapter 6 teaches you basic turning between centres and

then introduces turning with the work mounted on the lathefaceplateChapter7isaboutholdingworkinacolletandhowyoucan

make and use several different types of mandrel forworkholdingChapter 8 explains how to turn a taper using the top slide

theuseoffixedandtravellingsteadiesandmakingaformtoolChapter9explainshowtousedrillsandreamersinthelathe

includinghowtoselectthecorrectspeedsandfeedsChapter 10 shows the different ways to bore holes in the

lathewiththeworkheldinachuckmountedonthefaceplateorheldonthecrossslideChapter 11 explains how to use knurling tools and radius

turning tools as well as making simple form tools and basicproductionmethodsChapter 12 shows you how to use taps and dies to cut

internalandexternal threads in the lathe Italsoexplainshowto set upa simplegear train and cut a screw threadwith thehelpofascrewcuttingdialindicator

1BuyingYourFirstLathe

WHATSIZEOFLATHEDOIREQUIRE

ThefirstthingtoconsiderwhenbuyingalatheisthesizeoftheworkthatyouwanttodoWhatisthelargestdiameteryouwillwanttoturnonitandwhatisthelongestlengthyouwillneedtoturnA3frac12times18in(90times457mm)lathewillallowamaximumdiameterof7in (178mm) tobe turnedover the lathebed thelatterfigureisknownastheswingInpracticethoughthisisatheoreticalmaximumas it is stillnecessary toholdandclampthe article being turned The swing over the cross slide isusuallymuchsmallertypically2in(50mm)Many lathes however aremanufacturedwith a gapbed at

the headstock end to enable short items of a large diametersuchaslocomotiveortractionenginewheelstobeturnedLathes are also sometimes available as standard and long

bed lathes The long bed lathe as the name suggests allowslongermaterial to be turned within the capacity of the latheWhen turning longermaterial the diameter will be limited bytheswingoverthecrossslideThiswillbealotsmallerthantheswingoverthebedIfbuildingamodelsuchasatractionengineoralocomotive

the deciding factor for the size of lathe is likely to be thediameterof the largestpairofwheels thatneed tobe turnedBefore deciding on the size of lathe required you shoulddetermine the size of the largest diameter and the longestlength of material that needs to be turned Another factor indeterminingwhat lathe tobuy is theavailabilityof sparesand

accessoriesisthecompanystilltradingwillitstillbetradinginthe future and are there large amounts of secondhand partsandaccessoriesavailablefromtooldealersoroneBay

Atypicalinvertertoconvert240voltssinglephaseto240volts3phase

LATHEELECTRICS

Single phase electric is where the lathe plugs into the mainssupplyinyourhouseThemotorwillhavetheusualliveneutraland earth leads Lathes supplied for factory use usually havethree phase motors and require three live wires each of adifferentphaseThinkofaphaseasan incomingwaveon theseashore three successive waves make up the three phasesneededEachphaseisthesameastheprecedingonebuttheyareoutofsyncandallpeakatadifferenttime

Aforwardreversecontrolboxforaninverter

Convertersandinverters

Youcan runsome3phasemotors fromasinglephasesupplyviaaconverteroraninverterThemotor informationplatewillusuallysay240volts440voltsif it iscapableofrunningonaninverter Inside the motor there will be changeover tags tochange the motor from 440V down to 240V Follow theconverterinverter manufacturerrsquos instructions for furtherinformation It isnotusuallyverycomplicatedto runa240V3phasemotor from an inverter and thiswill give a quieter andsmoother running motor than a single phase supply canprovide This usually requires some simple programmingexplainedintheinverterrsquosinstructionsanditusuallytakesfiveminutestogetthemotorworkingproperly

ThismotorispartoftheinverterpackageshowninthepreviousillustrationNowiringisinvolvedasthemotorleadplugsstraightintotheinverterbox

Theinverterrunsataconstantvoltagebutthespeedofthemotor will change as the frequency is raised or lowered Isuggest limitingyour inverter from full speed tohalf speed sothatthefanstillcoolsthemotorandstopsitfromoverheatingyoucanthenusethebeltstochangethemainspeedstepsasusual(Ifyoumustuseveryslowrunningitispossibletoaddaseparatefansuchasacomputercoolingfantogiveconstantairflow) Most inverter suppliers offer a forwardreverse andspeedcontrolboxthatcanbesetupinaconvenientpositiononthe machine These are well worth fitting for convenience inuse

Thisinverterisdesignedformountingonthefrontofthelathe

While inverters are designed to run only onemachine youcangetconverterstopowermorethanonemachineatatimeDependingonthesizeandpoweroutputconverterscostaboutthreetofourtimesasmuchasaninverterTherearetwomaintypesofconverterRotaryconvertersare

designedtorunmorethanonemotoratatimeThisis ideal ifyouwanttorunmorethanonemachineortwomotorsononemachineforexamplethemainmachinemotorandperhapsanauxiliary motor that drives the machinersquos coolant pump orpowerfeedsystem

Arotaryconvertercapableofpoweringmorethanone3phasemotor

ThesecondtypeisthestaticconverterwhichisdesignedtorunonemotoratatimeThereisofcoursenothingtostopyouusingthestaticconverteronmorethanonemachinebyfittingasuitablefemaleelectricalconnectortothestaticconverterandmatchingmaleconnectorstotheindividualmachinesThiswayyoucanconnectthestaticconvertertoonlyonemachineatatime

Thisstaticconverterissuitableforpoweringone3phasemotorIfyoufitasocketontheoutputhoweverdifferentindividualmachinescanbepluggedintoitoneatatime

Theelectricalloadingonrotaryorstaticconvertersmustnotexceed theirmaximumrating If indoubton the loadcapacityneeded to run your machine(s) you should consult the

manufacturerorsupplieroftheconverter

AnearthleakagetripisidealforquicklyeliminatingamotorwheretheelectricalinsulationisbreakingdownItisusefulfordetectingcertainelectricalearthingfaultsbutshouldnotbeusedasaguaranteeofelectricalsafety

Simpleelectricaltestingandsafety

Whenbuyingasmallsinglephasesecondhandlathetakewithyouanearth leakage testerof the typeused for lawnmowersandothergardentoolsIonceboughtaUnimat3lathetookithomeandpluggeditinItkeptblowingtheearthleakagetripinthefuseboxeventhoughithadworkedperfectlyatthesellerrsquoshouseIsolditonatalossbutthebuyerdidknowtherewasaproblemwiththeelectricsIt is most important that the metal parts of any lathe are

connectedtotheearthwirewhichisinturnconnectedtoearthMake sure that themotor frame is also connected toearthassome motors have dampening rubber mounts that insulatethem from themachine itself If in doubt about any aspect ofelectricalinstallationpleaseconsultaqualifiedelectrician

Acontinuousbedisidealwhenworkingwiththefaceplateorwithcollets

LATHEBED

Thelathebedisthebackboneoftheentirelatheandisthepartthat is mounted on the bench or stand There are two maintypesoflathebedtheplainbedandthegapbedTheplainbedisusuallycontinuousallthewayalongitslengthwhilethegapbedhasas itsnamesuggestsagap in thebedThis isnotaliteralgapbutasteppedsectionthatallowsbiggerdiameterstobeturnedthanyouwouldotherwisebeabletoturnonaplainbed latheThisgap isameansofmakinga lathesmaller thanwouldberequiredforaplainlatheabletoturnasimilarsizeof

componentSome continuous lathe beds have a section next to the

headstock that can be removed to increase the diameter thatcanbeturnedThisfeatureisusuallyonlyfittedtolargerlathessuchasaremostlyfoundinfactoriesSome lathes have hardened beds although most are just

plaincast ironTherearethreemaintypesofbedwayscalledshearstheplainflatbedwithsquarewaysabedwithaflattopand a 60 degree dovetail at each side and a bedwith raisedandinvertedVeewaysOnthelastofthesethetailstockusuallyrunsononesetofVeesand thecarriageonadifferent setofVees resulting in lesswear to themain slidesWidebedsarebetterandmoreaccurateasthelathecarriageislesslikelytotwistonawidebed

Close-upviewofatypicallathebedwithagapAgapbedlathehasalargerturningdiametercapacitythantheequivalentsizedcontinuousbedlathe

Someveryearly lathessuchas thosemadebyDrummondhad a round bed Although they worked well there is noadjustmentforwearinthelathebed

TheMyfordrangeoflatheshasasquareformofbed

ThistypeofbedhasaflattopwithaninvertedVeeateachsideTheVeesareusuallysetat60degreesbutcanvarywithdifferentmakers

The Unimat SL lathe was sold for many years and manysecondhandexamplesarestillavailableThismodeldiffersfrommostlathesinthatithastwosteelbarsasabedThisisnotaproblemhoweverastheUnimatisintendedonlyforverysmallandlightweightmodel-makingworkandthereistheadvantagethatthebedcanbereplacedbyfittingnewbarsWhen buying a secondhand lathe it is most important to

checktheconditionofthebedYouneedtomakesurethebedis reasonably free from dings rust and hacksaw marksHacksawmarksneartheheadstockareoftencausedbysawing

offworkwhile it isheld inthechuckdingsareusuallycausedbydroppingthechuckonthelathebedwhenscrewingitonoroffthemandrelAsimplechuckboardplacedonthebedwhilefittingorremovingthechuckwillprotectthebedItisalsoidealfor protecting the bed when filing or hacksawing work in thechuck

AlathebedwithraisedandinvertedVeesThecarriageusuallyslidesononesetofVeesandthetailstockslidesontheother

AmodernChineselathebedwithaninvertedraisedVeeThecarriageandtailstockusuallyslideonthesameVee

Wear ismost commonly found at the headstock end of thelathe as a result of machining many short components andrelatively few long ones Make sure the lathe carriage isproperlyadjustedattheheadstockandthenrunitalongasfaras you can towards the tailstock The carriage should bereasonablyfreebutnotlooseallthewayalongthebed

OldroundbedDrummondlathesarestillavailablesecondhandThisparticularexampleistreadledriven

AflatbedlathewithsquarebedwayssuchasaMyfordcanbe checked for wear on the lathe bed using amicrometer orvernierCheckovertheworkingpartofthelathebedonwhichthe carriage slides rather than the part that is not used forguidance Check both the width and the thickness of the bedwaysThetailstockshouldalsobeagoodslidingfitonanyguiding

surfaces Wear is most likely to be found on the tenon thatslidesbetween thebedwaysAworn tenoncouldprobablybereplacedbutthereisnotmuchyoucandoifthetenonguidesarewornTheonlyway to fixawornbed requiresacompletebedregrindThisislikelytobeexpensivesoitwouldbebettertolookforanunwornlatheDecentunwornlathesareouttheresincemanymodelengineersmayhaveboughtthemnewfortyorfiftyyearsagoandhardlyusedthem

TheUnimatSLisaverypopularsmalllatheItsbedconsistsoftwosteelbarsthatcanbereplacedveryeasilywithsilversteeliftheygetwornormorelikelywhentheygetrusty

Asimplewoodenchuckboardwillprotectthelathebedfromdingsandhacksawmarks

LATHEHEADSTOCK

Theheadstockisthelargecomponentmountedattheleft-handside of the lathe bed It needs to have good bearings An all-gearedheadwillalmostcertainlyhaveballorrollerraceswhilethe older type of lathe for amateurs may well have plainbearings either phosphor bronze or whitemetal These areperfectlyadequatebutyoushouldmakesurethere isnowearinthemSomelathesalsohaveamandrelthatrunsdirectly inbored holes in the cast iron headstock casting Plain bearingswillbeperfectlysatisfactoryas longasadequate lubrication isused

Close-upviewofaMyfordheadstockonanML7RNotethelargebronzebearingatthefrontTheearlierML7latheshadwhitemetalbearingsalthoughtheC7capstanhadbronzebearingsandahardenedlathespindle

Tocheck forwear in the lathersquosbearings fitachuck to themandrelandputadialtestindicatorontopofthechuckGentlytry levering the chuck up and down by using a steel bar orsimilarheldinthechuckYouarelookingforminimalmovementhereespeciallyonaheadstockfittedwithballraces

CheckingthelathebearingsforwearAnymovementupanddownindicateswearinthebearing

The mandrel is mounted in the headstock and is usuallythreaded to take a chuck or faceplate The lathersquos mandrelshould not move back and forth in the bearings If it doeshowever itwillprobablybepossibletoadjust ittocorrectanyendwise movement The mandrel should not be too stiff butshouldturneasilybyhandWhentestingalathemakesuretheheadstockbearingsare

correctlyadjustedsothatwherepossiblethereisnoplaySeta tool up take a trial cut alonga length of bar and check forchatter If you are using a correctly set tool and a suitablespeedchatterisasuresignofwornbearings

Manylatheshaveathree-orfour-stepdrivepulleyasthesecondstageofthedrivechain

POWERDRIVE

Manylatheshaveathree-orfour-steppulleyonthemandreltotake the drive from a similar pulley on the countershaft Thecountershaft is in turn driven from the motor which is oftenmounted at the back of the headstock and completes theintegral drive system that is so popular on most amateursrsquolathes

Thisparticularlathehasatwo-stepmotorpulleyandcountershaftwhichdoublestheavailablespeeds

SpeedchartonthebeltguardofaMyfordML7Rlathe

AfewlatheshaveaclutchfittedasstandardorasanoptionalextraTheclutchsaveshavingtostartandstopthemotorwhileitisrunningThishelpstostopwearandtearonthemotorandelectricalsystemAdifferenttypeofclutchsystemtheTriLevaspeedselector

wasonlyfittedtoMyfordML7orC7lathesThishasthreeleversfor setting threedifferent speedsDependingon the leveryoudepressyougetahighmediumorlowspeedIfyoupressoneof the levers downwhile another is right down the first leverwilldisengagethesecondsostoppingthemandrelfromgoinground If the lathe is switched off and all three handles aredepressed the mandrel is locked preventing rotation This isusefuliffilingorhacksawinginthelathe

TheclutchisnormallymountedinsidethelargecountershaftpulleyItisusuallyoperatedbyaleverattheright-handsideoftheheadstockattachedtoapushrodthatpassesrightthroughthecountershaft

TheMyfordTriLevaattachmentwillonlyfitML7andC7lathesandisnotsuitableforML7RorSuper7lathes

Therehasbeenatrend inrecentyearstodoawaywiththecountershaftandpulleysystemandtoreplacethemotorwithavariable speed one with an electronic controller This isacceptable except that at low revolutions it does not providethe torque that can be obtained from a countershaft systemThereisalsothedisadvantagethatthereisnowaytodrivethelatheifthecontrollercircuitboardfailswhereasyoucanjustfita new one if the belt breaks The board could of course befixed provided that a circuit diagram is available and theelectronic components can be identified Sometimes thecomponents are marked with internal house numbers ratherthan commercially recognized part numbers that can beorderedasareplacementfromacatalogueSomeboardsmighteven have the identification marks removed to make repairsalmostimpossible

ThethreadedendofalathemandrelisdesignedsothatthechuckbackplaterunstrueIfthechuckmountingfaceofthebackplateismachinedinsituthechuckshouldruntrueaswell

CHUCKMOUNTINGSYSTEMS

The threaded lathe mandrel nose is not by itself a suitablelocationforachuckorfaceplatesothenoseisusuallygivenaturned register on which to locate the chuck The chuck isscrewedrightontothemandrelovertheregisterandbuttsuptoaturnedcollartokeepthechuckrunningtrueTheothersideof the mandrel collar butts up against the main headstockbearingwhichusuallyactsasathrustfaceThemandrelisusuallyboredthroughandmachinedtotakea

MorsetapercentreforturningbetweencentresDonotputyourfingerineitherendofthemandreltocleanitwhilethelatheisrunningAneasywaytocleanthetaperintheheadstockiswithabottlebrush often sold in chemists to cleanbabiesrsquo bottlesAnalternativeisasoftfeltshotgunbrushdonotuseonemadefromwire

ThislathehasaplainregisterAccuracyreliesonthelathechuckbeingagoodfitontheregister

There are various systems of chuck mounting in useespeciallyon the larger lathesTheproblemwith thescrew-ontype with a register mentioned above is that the chuck orfaceplatecanunscrewwhenthelatheisrunninginreverseTheonly timeyoushould run this typeofmandrel in reverseveryslowly and without taking a cut is if you need to return thescrewcuttingtooltothestartofthethreadyouarecuttingAlternativespindlenosescanbeaplaindiscwitharegisterto

boltthechuckontooracamlockwherethechuckisheldontightlybyturningstudstolockthechuckontothemandrelTheplain discwith register relies on having chuckswith amatingregistertoworkproperly

AnAmericanstandardCamLockchuckmountingbackplateandCamLockchuckplatefittedtoachuckTheyareusuallyfittedtolargerindustriallathes

TheAmericanDstyleCamLocksystemeithertakesachuckor faceplate directly or it has a backplate that can have aregisterturnedonittosuittherequiredchuckAlthoughmanylathe mandrels with Cam Lock fittings have six holes thematchingchuckorfaceplateoftenhasonlythreelockingpinsThe advantage of both of the last two systems is that they

canberuninreversewithoutthechuckcomingoffthemandrel

Theleadscrewisdrivenfromthemandrelviaageartrain

SCREWCUTTINGGEARS

The left-hand end of the mandrel will often have a gearmountedonittodrivethechangewheelgearsandleadscrewThe mandrel gear usually drives a pair of gears called

tumblergearswhicharemountedona leveratthe leftoftheheadstock The direction of the leadscrew can be changed bybringingeitheroneortheotherintogearbyraisingorloweringaleverThereisusuallyacentralneutralpositionwhereneithergearisinmeshThissaveswearonthelathechangewheelsandleadscrew bearings as well as reducing noise while workingMandrelandtumblergearswillbediscussedfurtherinChapter12whenwesetupascrewcuttinggeartrain

A set of changewheels usually comprises about a dozengearsbutthiscanvarydependingonthemanufacturerThesechangewheels which take the drive from the tumbler gearsdown to the leadscrew are mounted on moveable studs toensurethegearsareinmeshwitheachotherDependingonthenumber of gears in the train the leadscrew will turn eitherclockwiseoranti-clockwiseThedirectionof the leadscrewcanbe reversed using the tumbler gears to enable right-hand orleft-handthreadstobecut

Oftentherearetumblergearsinthegeartrainthatcanreversethedirectionoftheleadscrew

YoucanusuallysetthegearstocutaveryfinepitchsothattheleadscrewactsasaselffeedwhenturningfromthesaddleIf you anticipate the need to do any screwcutting check thatthesuppliedscrewcuttinggearswilldotherangeofpitchesyourequire It has been known for certain lathes to be unable tohandle somecommonpitches a typical examplebeing26TPI(teeth per inch) A pitch of 26 TPI is often needed to repairmotorcycles and bikes made before the introduction ofmetrication

MakesurethatafullsetofchangegearsisincludedwiththelatheIfnottheyarereadilyavailablesecondhand

LEADSCREW

The leadscrew ismounted at the front of the lathe there areusuallybearings to support the leadscrewateitherendof thelathe bed It is used tomove the lathe saddle along the bedeither for a self acting feed or for screwcutting Some lathesalso have a graduated handwheel mounted at the right-handendoftheleadscrewforturningthemandrelbyhandSome of the larger lathes also have a separate feed shaft

whichisusuallyaplainroundshaftwithakeywaycutalongittodrivethesaddleusingafinefeedThissaveswearandtearontheleadscrewwhichisthenonlyusedforscrewcutting

Mostleadscrewscanhaveagraduatedhandwheelmountedontheright-handendoftheleadscrew

SCREWCUTTINGFACILITIES

Ausefulfeatureonanylatheistheabilitytocutscrewthreadsof different pitches Leadscrews come in different pitches acommon one being 8 TPI but many variations are fitted todifferent lathes including leadscrews with a metric pitch It isawkward tomachinemetricscrewswithan imperial leadscrewandviceversaSometimesmetricconversionsetsareavailablebuttheycanbehardtofindareusuallyexpensiveandrequirethe lathe to be changed over often using 127 tooth gearwheels This figure is derived from multiplying the metricequivalentof1in(254mm)byfivea127toothwheelisthusadirectconversiontoametricthreadonalathewithanimperialleadscrewA127 toothgear isusuallyvery large if itmatchesthepitchoftheremainingscrewcuttinggearsbutyoucouldusesmallergearswitha smallerDP (diametralpitch)but stillwith127 teeth Youwould also need amatching gear of say fiftyteethtogiveyoua2541ratio

Thislathehasbothaleadscrewforscrewcuttingandadriveshaftforthesaddleandcrossslidefeeds

Ascrewcuttingdialindicatorusuallymountedtotherightofthe carriage is a useful feature This is a small dial withdivisionsmarkedonitmountedonashaftTheotherendoftheshafthasagearthatmesheswiththeleadscrewandmakesthedial go roundWhen the clasp nuts are engaged the carriagemoves and as the gear moves at the same speed as thecarriagethedialstopsgoingroundWhen you engage the clasp nuts on the leadscrew the

positionwhereyouengagedependsonthepitchofthethreadbeing cut Some thread pitches allow you to engage at anydivision of the dial while others need to be engaged at aparticularpositionof thedialTheuseof thescrewcuttingdialindicator will be covered in Chapter 12 When using the finefeedyoucanengagetheclaspnutsatanymarkedpositiononthedialsoavoidingweartotheclaspnuts

AtypicalscrewthreaddialindicatorThisoneisengagedanddisengagedbylooseningtheboltandengagingthedrivegearwiththeleadscrew

LATHESADDLEANDAPRON

The saddle is thepart that slides on top of the lathebedandusually has the cross slide and top slide mounted on it Theapron ismounted to the frontof the saddleYoushouldmakesure there isnoplay in the saddle either sidewaysorupanddownandthatittravelsfreelyfromoneendofthelathebedtotheotherwithnotightspotsAtthefrontnearesttheoperatorthereisusuallyapairofclaspnuts(thesearesplitnuts)Thesecan be engaged or disengaged from the leadscrew forscrewcuttingormovingthesaddlealongwiththeleadscrewOncheaper lathes there is usually a solid nut that cannot bedisengaged

ThelathesaddleslidesalongthelathebedTheapronisboltedtothefrontofthesaddle

There is often a rack at the front of the lathe bed thatmatches upwith a handle and gears on the lathe apron Thiscan be used to move the carriage along the bed withoutwearingouttheleadscrewSomelatheshavethecarriagefeedwheel on the right but others have it on the left where hotswarfcanfallontoyourhandsThecheaperlatheshavenorackandrelyontheleadscrewtowindthecarriagebackandforth

ATee-slottedcrossslidemakesthesmalllathemoreversatile

CROSSSLIDE

On top of the carriage is the cross slidewhich canbewoundbackandforthacrossthelathebedWhenusingthecrossslideforfacingacrosstheworkthecarriageshouldbelockedtostopitmovingalongthebedLathesforamateurusearemorelikelytohaveaTee-slottedcrossslidewhilelargercommerciallathesare unlikely to have this facility The Tee-slotted cross slide isveryusefulespeciallyifyoudonrsquothaveamillingmachineYoucanboltworktothecrossslideformachiningusingacutterinthechuckorforboringworkpiecesthataretoolargetoswinginthechuckZero settingdials aredesirable for both the cross slide and

thetopslideTheyallowyoutosetthedialtozerowhichmakesiteasiertomeasuretheamountyouaretakingoffwithonecutInusewindthetooluptotheworkandtouchonsetthedialtozeroandwind the toolbackoff from theworkYounowknowwherezeroisonthetoolandcantaketherequireddepthofcut

withouthavingtoworkitout

Zerosettingdialsmaketurningandscrewcuttingtodepthveryeasy

Apairofzerosettingdialsreadytofit

LathescanbepurchasedwithimperialormetricfeedscrewsMostmodeldesignsareimperialbutmetricismakingheadwayandthismaywellbethewaytogoBewarelatheswithimperialfeedscrewsandmetricdialsTypically thesewillhavea funnynumber of handwheel divisions rather than a whole numberMostofthelathesyoumightcomeacrossareunlikelytohavea

power cross feed for facing This does notmatter as you caneasilywindthecrossslideacrossbyhandTheonlytimeIhavefound a power cross feed to be of use is when I had to faceacross a faceplate to true it up I have trued up similar sizefaceplatesbyhanditjusttookalittlelonger

Thetopslideismountedonthecrossslide

TOPSLIDE

ThetopslideismountedontopofthecrossslideThetopslideisnormallysetat90degreestothecrossslidealthoughitcanusually be swivelled around to various angles for turning ataperanangleorforscrewcuttingSomeofthecheaperlathesdonrsquothaveatopslideasstandardbutitisaveryusefulfeatureif you can get one The top slide should be able to rotateespecially for screwcutting but the top slide handlemay foulthecrossslideincertainpositionssocheckifthisisaproblemTheturningtoolisusuallymountedonthetopofthetopslideItcan either be clamped on directly usually with packing stripsunderneathorthetoolcanbemountedinatoolholdersuchasathree-orfour-waytoolpostoraquickchangetoolpostWewilllook at tool holding methods in Chapter 4 when discussingsettingupturningtools

TAILSTOCK

The component at the right-hand end of the lathe is thetailstock This usually has a handwheel to feed a drill into theworkbut leverfeedandcapstan-style feedingmechanismsarealso available You can lock the tailstock anywhere along thebed The tailstock has a barrel inside it that can bewound inandouttogivealinearmovementtodrillaholeinworkheldinthechuckThetailstockisusuallyboredtoaMorsetaperoftenof a similar size to the headstock so it can take accessoriessuchasdrillchucksmountedonaMorsetaperItcanalsotakeacentre for turningworkbetweencentres It is important thatboth the headstock and tailstock tapers are free frommarksscratchesandburrs

AlathetailstockwiththebarrelextendedNotethatitisnotusuallyaproblemifthechuckkeyisleftinthetailstockwhilenotinuse

Adjustment is usually provided between the base and themain body of the tailstock to allow for setting the tailstock inlinewith theheadstock Tailstocks canbe self ejectingwherethetool isextractedas it iswoundbackwhilesometailstockshavea throughholeandneeda tapwithabar to remove thetool Handwheel depth graduations for drill drilling to a

particularholedepthareveryusefulbutarenotoftenincludedon the cheaper lathes although industrial lathes usually havegraduatedtailstockhandwheelsThebettermakesoflathehavea lever clamping tailstock arrangement while the cheaperlathesoftenhaveaclampingspanneroranAllenscrewclamp

Allguardsshouldbefittedinplacebeforeoperatingthelathe

MACHINEGUARDS

Thedrivemotorcountershaft(iffitted)andpulleybeltsshouldallbeproperlyguarded It isveryeasy togetcaughtup inanunguardedmachineandtheconsequencescanbequitenastyThis has never happened to me but I have seen someonecaught up in a machine and it was not very nice I dorecommend that you make sure your machine guards arecorrectlyfitted

OTHERDESIRABLEFEATURES

Digitalreadoutsareusefulonalatheastheycanshowyouhowmuch to move the handwheels and how much material hasbeentakenoffTheyarequiteexpensivebutyoucan fit themyourself if youare carefulUnfortunatelymost of the cheaperversionsdislikesolubleoilorothercoolantifyougetitintothereadouthead

Adigitalreadoutsuitableformountingonalathe

Youwillneedtwoslidesoneforeachaxis

A soluble pump for cutting fluid is useful and often comesfittedasstandardonthelargerlathesHoweveratinofcuttingoilandabrushwillbegoodenoughformostworkandthatmaysuityoufine

Solubleoilpumpsandreservoirsarereadilyobtainable

Formostjobsyoucangetawaywithsomecuttingoilabowlandabrush

TheMyfordlsquoNortonrsquostylequickchangescrewcuttinggearbox

A Norton quickchange screwcutting gearbox saves time asyou donrsquot have to set up changewheel trains A gearboxhowever considerably increases the price of the averagesecondhand lathe A Myford Norton gearbox has twenty-fourpitchesandiscontrolledbytwoleversReversingtwogears inthe Myford changewheel train gives the gearbox twenty-fourfine feeds insteadof the twenty-fourscrewcuttingpitchesThegearboxhasa setofgearsarrangedasaconeBysliding thelever along and dropping themaster gear onto the cone youcanchangethegearboxratioandsothepitch

TheconegearsinsideatypicalNortonscrewcuttinggearbox(notanoriginalMyfordone)

SeveraldesignshavebeenpublishedtomakeyourownNortontypescrewcuttinggearboxThisoneisavailablefromHemingwayKits

SPINDLESPEEDS

Thespeed rangeneededona lathedependson thework it is

requiredtodoAgoodrangeofspindlespeedsisdesirablewithnoobviousgapsWithelectroniccontrolthisshouldnotbetoomuchofaproblemIdeally a back-geared lathe would be best but this means

either a good secondhand machine such as a Myford or aBoxford or alternatively one of the larger Asian-made latheswithanall-gearedheadstock

Thisbackgeararrangementisswitchedinandoutbyturningthetoggleonthepulleyandliftingaleveratthefrontofthelathe

Backgearnormallyconsistsoffourgearstwolargeonesandtwosmalloneswhichcanbeswitched inorout toreducethespeedofthelathebyaratioofusuallyabout51dependingonthe maker to enable you to turn large diameter workpiecesThis reduction is also essential on a screwcutting lathe asotherwisethemandrelwillbegoingtoofastwhilescrewcuttingandyouwonrsquotbeable tostop in the rightplaceat theendofthethreadIf buying a back-geared lathe check that both gearwheels

havealltheirteethItisamajorjobtostripdownalatheandfitnewgearwheelsassumingtheyareevenavailableassparesCheckthelatheinallgearrangeswiththelatherunningIfa

back-geared lathe or an all-geared head is noisy it could

indicatewearitwillalsobeanuisanceinyourworkshopasnoonewants to hear a noisymachine runningNoise could be amajorproblemespeciallyifyouhaveneighboursnearbyGearedheadsusuallyhaveawiderangeofspeedsthelarger

industrial lathescangoup tospeedsof2000rpmandsmallerversionsareoftenhigher

Anall-gearedheadonamodernindustrialsizelathe

On the more usual amateursrsquo lathe there is often acountershaft usually tensioned by a lever which tightens upthebeltreadyforuseThemiddlespeedofthecountershaft isusually chosen to be about one quarter of the motor speedMost small lathes have three speeds and the back geararrangement adds another three speeds giving six in all TheMyfordSuper7rangeoflatheshavefourspeedsandbackgearmaking eight speeds but there is also a double pulley on themotor countershaft section making sixteen speeds in allalthoughtheverylowestback-gearedspeedswillrarelyifeverbeusedSomeoftheolderColchesterChipmasterlatheshavewhatis

knownasaKoppVariatordriveThis isavariable speeddrivecontrolledbyadialandthesystemworkswellbuttheVariator

isveryhardtoreplaceifthedrivefails

ThissmallCowellslatheiscapableofdecentworkandatthetimeofwritingisprobablytheonlylathestillbeingmadeinBritain

MOUNTINGTHELATHE

There are three main options for mounting a lathe benchmounting portable or on a stand Ideally a makerrsquos standshouldbeusedformountingamediumto large latheandthestandisoftenanintegralpartof larger lathesAsmaller lathesuch as a Unimat or a Cowell can bemounted on a woodenchopping board or a similar small board These lathes can beputawayinacupboardafteruseThe alternative is a workbench but these are often made

from wood which can expand or contract depending on themoistureintheairWoodisnotagoodmaterialfromwhichtomakea stand for a larger latheas itwill attractmoisture andmayexpandshrinkordistortAmetalstandisabetteroptionWewilllookatinstallingthelatheinChapter2

AnArcEuroTradeC3screwcuttinglathemadebySiegThisisaverypopularentrylevellatheandmanyaccessoriesareavailable

Amedium-sizedscrewcuttinglathesuitableforgardenshedworkshops

SHOULDIBUYNEWORSECONDHAND

Beginnerssettingupaworkshopoftenaskifitisbettertobuyanew lathe or secondhand The preceding pages should have

given some guidance but there are more points to be takenintoconsideration

Alargerindustriallathewithafoot-operatedemergencycut-offswitchandbrake

BuyingNew

Thelistoflathesuppliersincludedatthebackofthisbookwereall in business at the time of writing Most will be willing todemonstratetheirrangeofmachinesattheirpremisesorwhileattendingmodelengineeringexhibitionsPaycloseattentiontomechanical noise the general paint finish and the workingslideway surfaceswhich should begroundDoes themachinehave sharpor roughedges (Handwheelsareespeciallypronetosharpedges)The main thing to consider though is the attitude of the

supplier Were they willing to talk to you and answer yourquestionseitheratanexhibitionoroverthephoneHowlongdo they take toanswer thephonewhenyou ring their servicedepartment Do they know the answer to a simple questionstraightawayordotheyhavetogetbacktoyouIsthemanual

written in English or Chinglish (translated awkwardly fromMandarinorCantonese)There are several suppliers of new lathes inmost countries

aroundtheworldbutthemajorityoflathesaremadeintheFarEastOftensupplierArsquosmachinescomefromthesamefactoryassupplierBrsquostheyarejustpaintedadifferentcolourandhavedifferentnamesandlabelsfittedAftersales service can vary greatly Usually companies that

havebeeninbusinesslongerwillofferbetteraftersalesservicebutotherpeoplersquosexperiencescanbefoundonInternetforumsoratlocalmodelengineeringclubsUsually theAsian lathesare reasonablywellmadebut they

often suffer from having plastic gears instead of metal onesOneortwocompaniessupplymetalgearsasstandardso it isworthaskingiftheirmachineshavemetalorplasticdrivegearsSome companies also offer after-market replacement metalgears

BuyingSecondhand

There aremany good quality secondhandmachines availablebut there is also a lot of worn-out rubbish If possible take aknowledgeable friend with you when purchasing a lathe Becareful when buying at online auctions such as eBay MostsellersaregenuinebutsomearenotNeverpartwiththecashuntil youhavechecked the latheover IhaveboughtoneBaywithoutproblemsbut Iamcarefulwhat IbuyandwhofromAsmall latheforacoupleofhundredpoundsisunlikelytobreakthe bank if it is a bit of a dog but a lathe that costs severalhundredpounds is adifferentmatter ThegreenMyfordML7RpicturedthroughoutthisbookwaspurchasedfromeBayItwasbrand new the motor had never been fitted and it was abargainwhencomparedwiththeretailpriceIdidpaycashoncollectionbutIwouldhavewalkedawayif ithadnotmatchedthedescriptioninanywayWhether purchasing new or secondhand check what

accessoriescomeaspartofthepackageandwhatwillneedto

bepurchasedseparatelyEssentialtoolingcanoftendoublethecost of a newmachine if it is not included in the price whilededicatedtoolingmaynotevenbeavailable forasecondhandbargainlathe

Youshouldnowhaveanideaofthesizeoflatheyouneedthefunctionofthedifferentpartsofthelatheandwhetheryouarebuying new or secondhand In Chapter 2 we will look atinstallingthelatheandsafetyintheworkshop

2InstallingtheLatheandUsingItSafely

If you are buying a new lathe completewith delivery to yourworkshopyoucangostraighttothesectiononsettingthelatheupIfyouarecollectingthelatheyourselfhoweveryoushouldpayattentiontoafewwordsonmovingit

Ifyouhaveroomtomanoeuvreanenginehoistcanbeusedtomovemachineryaroundsafely

MOVINGTHELATHE

MOVINGTHELATHE

When going to collect your lathemake sure someonewill betheretohelpyouloaditortakesomeonewithyouUnlessitisaminiaturelatheitwillbetooheavyforonepersontoliftHelpisalsoneededwhenyougetthelathehomeLiftingthelatheoutofacarcanbeharder than lifting it in It isadvisable tohavethreepeoplewhenunloading twoat theheavyheadstockendandoneliftingthelightertailstockendYoucanrentorbuyanenginehoist fora reasonablepriceand this canmakemovingthemachineeasierIf the machine is a substantial industrial type it would be

besttohireatransportcompanythatspecializes inmachineryremovals Professional machinery removers will usually haveproperlyequippedtransporttomoveheavymachinesThiswillprobablyworkoutcheaperthanattemptingtodoityourselfbutmake sure they have insurance in place in case they damagethelatheoryourpropertyYoushouldalsoensuretheyknowithas to beput in place as required in theworkshop youdonrsquotwanthalfatonofmachinerydumpedonyourdrivewithnowayofmovingitintopositionLathesareusuallytopheavywhenbeingmovedandcantip

overifyouarenotcarefulTheMyfordML7seriesforexampleoftenhasthemotorandcountershaftboltedtothebackofthelathe bed and this type of lathewill tend to tip backwards Asimple solution is to bolt two lengths of wood about 4 times 2in(100times50mm)tothelathefeetOneboltineachendwilldoifyou canrsquot drill holes in the correct position This will stop thelathe tipping backwards and also make it easier to lift IfpossibleyoushouldremovethetailstockThisisoftenaheavylumpofmetalbutitisusuallyveryeasytoslideitofftheendofthelathebedAnyotherlargeobjectsthatcanberemovedandreplacedlaterwillmakethelathelighterandeasiertomove

Twoplanksofwoodboltedtothelathefeetwilloftenturnanunmanageablemassofmetalintoaneasilyhandledmachine

Azerovoltsswitchisessentialequipmentonanymachinetool

Wearoldclotheswhenmovingyourlatheandhaveplentyofold rags to wipe off swarf and oil Lay down old blankets ordecoratorsrsquosheetsinsidethecarandasheetofthickcardboardMDForplywoodtohelpprotectthebootareawhenslidingthelatheintothecar

AsmallishlathecanoftenbefittedintoastandardhatchbackorestatecarYoumayfindhowever thatyouhavetodotwotrips one for the lathe and accessories and another for thecabinetthelathestandsonTosaveawastedjourneyIusuallytrytofitthelathecabinetinfirstIfIthenfindthatthecabinetdoesnrsquotfitIcanstillbringthelatheandtoolinghomeknowingthat Ihave tohireavan tocollect thecabinetbutalso that IhavenothadawastedjourneyIfyouhavetosplittheelectricsforexampletotakethelathe

offthecabinetdrawadiagramoftheelectricalconnectionssoyoucanrewirethelathewhenyougetithomeAdigitalcameraisalsoagoodmethodofrecordingthewiringconnectionsbutIwouldnotrelyonthecameraaloneIf the lathedoesnothaveazerovoltsswitch itwouldbea

good idea to fit one after you get the lathe home They areavailable quite cheaply andare easily fitted If in doubt aboutyourabilitytodoelectricalwiringconsultaqualifiedelectrician

Adjustablefeetareveryusefulforlevellingupthelathe

SETTINGUPTHELATHE

Somelathesusuallythelargerindustrialoneshaveanintegral

bedandcabinetThelathecanbesettotruewithjustshimmingunderthefeetorbyadjustingthefeetOther lathes may need to be mounted level and true to

ensureaccuracywhenturningSetthebenchstandas levelasyou can in both directions using a spirit level as a guide Anycheapspirit levelwilldoas longas it isaccurateYoucantesttheaccuracyofaspiritlevelbyturningitround180degreesifitisaccurateitshouldreadthesamebothwaysOnce the stand is reasonably level youcan level the lathe

ThisinvolvesjackingorshimmingupthelatheuntilitistrueinbothdirectionsIfusingawoodenbenchputmetalplatesunderthe feet tospread the loadShimoradjust the latheuntil it isreasonablylevel

Putthespiritlevelonthecabinetrsquoslongitudinalaxisandusetheadjustablefeettolevelthelathe

Insertalengthofbarinthechuckandputadialtestindicatoron top of the tailstock end of the bar Nip the headstock endmounting bolts down first and then tighten down the tailstockendboltsAdjustorshimthetailstockenduntilthereisnosignof movement on the test indicator Next 64repeat theprocedure with the dial test indicator on the front of the barAgainyouare looking fornomovementCheckbothdirectionsagainmakingsurethereisnomovementeitherhorizontallyorverticallywhenyoutightenthelathedownAdjustorshimuntil

there is no movement in either direction when the lathe isclampeddownAslongasthebedisnottwistedthelathebedshouldnowbetrue

1Insertapieceof⅛in(3mm)packingunderthespiritlevelatthetailstockendThiswillresultinarunonthedriptrayandalltheoldoilwillruntotheendofthelathemakingiteasiertocleanup

2Placethespiritlevelonthecabinetcrossaxisandusetheadjustablefeettolevelthelathe

3Putthespiritlevelonthelathecrossaxisattheheadstockendandlevelitasbestyoucan

4Putthespiritlevelonthelongitudinalaxisandlevelalongthelathe

5Testthetopofthebarthereshouldbenomovementwhenthelatheisclampeddown

6Testthefrontofthebaragainensuringthatthereisnomovementwhenthelatheisclampeddown

Alignthetailstockbyusingadialtestindicatorintheheadstock

AligningtheTailstock

NowweneedtosetthetailstockinlinewiththeheadstockDothisbyputting thedial test indicator into theheadstockchuckandtestthetailstockboreAdjustthetailstocktowardsthefrontortothebackofthebeduntilthetestindicatorreadstrueandtighten theclampscrewsA slightdifference inverticalheightwillnotbetheendoftheworlditjustmeansthereisprobablysomeweartothebaseofthetailstockcastingbutthereshouldbenovariationfromfronttobackinthehorizontalalignmentPutalongbarbetweenthecentresandtakealightcutalong

it using a fine power feed Run along the bar a couple moretimes at the same setting to remove any push offWhen youmeasure thebar it shouldmeasure the sameatbothends Ifthe bar is larger at the tailstock end you need to reduce theheightofthebedatthefrontofthetailstockslightlyIfsmalleratthetailstockendyouneedtoreducetheshimatthebackofthe tailstockend Itprobablywonrsquotneedmuchadjustmentasslightadjustmentstotheshimoradjustersatthetailstockendwillsoonbringitintoline

Usingatestbartocheckforparallelturning

LubricatingtheLathe

You should follow the manufacturerrsquos recommendations forlubrication Usually this is thin oil for the headstock oftenhydraulicoilandslidewayoil forthemovingpartsLubricationshouldbedoneregularlyIfthelatheisfittedwithasightfeedoileritshouldshowoilinitAdjustablesightfeedoilersasusedonMyfordandsimilarlathesshouldbeadjustedsothattheoildripswhen the lathe is running but does not dripmuchwhenthe lathe is stopped The slight vibration when the motor isrunningisusuallyenoughtocausetheoiltodripToomuchoilisbetterthannotenoughoilisfarcheaperthannewbearings

Atypicaldrip-feedlubricator

UseanoilgunonalltheoilnipplesYoucangetaroundthetendencyfortheoiltogoeverywhereexceptintothenipplebyputtingapieceofwritingpaperoverthenippleandthenusingthe oil gun as normal The paper will stop the oil squirtingeverywhereThemandrelbackgearalsoneedstobelubricatedWheninusethemainbackgearisrunningontheoutsideofthelathemandrelandneedstobelubricatedoftenoritwillgethotandwearChangewheels should be lubricated with oil not grease If

youusegreaseswarfwillsticktothechangewheelsandcauseunnecessarywearTo stopswarf running through themandrelanddroppingoutontothechangewheelsputawinebottlecorkor similar into the left-hand end of the mandrel This willeffectivelystopanyswarfgettingthroughtothechangewheelsOil the saddle and cross slide and also the nipples on the

tailstock Make sure oil is showing at the edge of the slidingsurfaces A squirt of oil on the cross slide and topslide feedscrew bearing is needed as well Check the manufacturerrsquosinstructions for lubricating the rest of the lathe Follow themotormakerrsquosrecommendationforlubricatingthemotorTrytoavoidusingWD40onthelatheWhileitisanexcellent

lubricantwaterdisplacerittendstodiscolourthelathebed

Useabitofpaperundertheoilguntostoptheoilsquirtingeverywhere

AvoidingtheRustFairy

Rust canplayhavocwith a lathe quickly turning thebedandother parts into a brownmess Various sizes of plastic coverssuitable forcovering lathesareoftensold foruseasbarbecuecoversinDIYstoresAplasticlathecoverwillhelptokeeprustatbaybutmoreneeds tobedoneAbagcontainingsilicagelplacedundertheplasticcoverforexamplewillabsorbexcessmoisturesilicagelcanbeboughtverycheaplyoneBay

SilicageliseasilyobtainablefromeBay

Alternatively you can buy a vapour phase inhibitor forprotecting the lathe The vapour phase inhibitor chemical issuppliedonafeltpadinsideaplasticpotThechemicalformsaprotectivelayeroneverysurfaceBecauseitisavapouritwillfind its way into every cranny and is also used for protectingtools and accessories in tool cabinets and drawers It usuallylasts for twelvemonths ifenclosedby theplasticcoverSomemachinetooldealersareabletosellsuppliesofthisproductinsmall ready to use containers rather than in industrialquantitiesAlwayscleanthelathedownafteruseswarfwillsoonrustif

leftonalatheasitwillprobablybecleanfromturningandwillnotbeprotectedbyoilTheuseofanovencookingtrayunderthe lathe bedmakes it easy to remove swarf at the end of aturning session The tray also helps to retrieve a parted offcomponentora lost screw froma tipped turning toolAnotheralternativeistocoverthelathechiptraywithnewspaperwhenyouhave finished turning remove thenewspaper screw it upandthrowitawayWhenfittingachuckorfaceplatetothelathemakesureyou

cleanthemandrelthreadtheregisterandthefaceYoushouldalso clean the mating threads the bore and the face on thechuckorfaceplateYoucancleanthethreadandboreeasilybyusing two toothbrushes bolted back to back with spacers inbetween Make sure the Morse tapers in the headstock andtailstock are cleanbefore fitting aMorse taper accessory TheMorse taper to be fitted should be free from scratches burrsandbruisesIt is good idea tomake a chuck board for usewhen fitting

chucks to a lathe or removing them This is a piece of wood(plywood will do) that sits on the lathe bed while you arescrewingthechuckonandoffThechuckboardwillprotectthelathe ifyoudrop thechuck It canalsobeused toprotect thelathebedwhenyouarehacksawingorfilinginthelatheIf you keep your lathe clean and lubricate it regularly it

shouldlastalifetime

AlargetraywillcatchmuchoftheswarfandtheholeslettheoildrainawayUsenewspapertosoakuptheexcessoil

SAFETYINTHEWORKSHOP

RememberyouareresponsibleforyourownsafetySafetyisamajorconcernintheworkshopTherearecertain

thingsyoushoulddoandobviouslythingsyoushouldnotByitsverynatureaworkshopcanbeadangerousplaceallwecandoismakeitassafeaspossiblewhilestillallowingustoworkinit

WorkingAlone

Mostofyoureadingthisbookwillprobablybeworkingaloneinasmallworkshopgarageorgardenshed IfyougethurtyoumaypossiblybeonyourownAsapriorityIsuggestyoutakeamobilephoneintotheworkshopandkeepitinyourpocketTheability to contact your family a friend or the emergencyservicesquicklycouldsaveyour lifeKeepthephoneswitchedoff while in the workshop however as it is an unnecessarydistraction

FirstAid

FirstAid

AFirstAidboxwithcontentsisanecessityandshouldincludeaneye-bathandeyewashYoushouldparticularlylearnhowtostopbloodflowingThereareplentyofwebsitesthatwilltellyouhowtodothisCheckthemoutnowbeforeyougobackintotheworkshop

ElectricalSafety

Checkforearthcontinuitywhilethemachineisunpluggedwithavoltohmmeterfromtheearthpinonthethreepinplugtothemetalpartofthelathe(somepaintmayhavetoberemovedforareadingtotakeplace)Youshouldgetareadingofzeroohmsorabeep if themeterhasacontinuity rangeYoushouldalsobe sure that the electrical sockets on the wall are correctlyearthedIfindoubtconsultacompetentelectricianLightingandelectricheatingshouldbeonaseparatecircuit

tothemachinessoyouwillstillhavelightifthemachinestripoutPlugasmalllightintothemachinecircuitsoyouhavesomelight if the lighting circuit trips out When I go on holiday Ialwaysturnoffthefusetripsforthelightinginordertomakeitmore difficult for intruders to move about quickly Leave thehouse alarm and smoke detectors on (The house alarmmayactivateeighthoursafter theelectricity is turnedoffwhenthebatteryexpires)

Adigitalmultimeterisveryusefulinthehomeworkshop

BeAware

Bementally alert while using the lathe Avoid operations thatmightputyourhandsatriskofenteringthemovingpartsofthelathe Do not operate any lathe while under the influence ofdrugs alcohol or prescription medication that may causedrowsinessorotherwiseaffectyourability to control the lathesafelyDonotattempttoworkonalatheandtalkatthesametimeIfyouhavetotalktosomeoneswitchoffthelathebeforedoingso

KeepItClean

TheareaaroundalatheshouldbekeptfreeofobstructionsThefloorshouldbecleananddrywithanyoilorotherspillscleanedup immediately The lathe should be kept clean and tidyMachinedangerareasshouldbemarkedontheworkshopfloorand observed Workbenches placed near a lathe should be

strongandequippedwithanon-slipsafetysurfacetostoptoolsor other items rolling onto the floor a rubber car mat willsufficeA rubberdoormat on the floorwill allow swarf todropthrough in order to save you getting swarf embedded in thesolesofyourshoes

Asuitablefloormatwillallowswarftodropthroughandhelpkeepyourfeetwarminwinter

LearntoUsetheLathe

Donotuseany lathebeforeyouare familiarwith thecontrolsandareawareofthedifferentwaysofstoppingitThismaybea clutch an onoff switch a No Volts release switch or anemergency stop button I strongly advise fitting a No VoltsreleaseswitchifyourlathedoesnothaveoneAswellasbeingusefulforstoppingthelatheinanemergencyitwillpreventthelathefromstartingupbyitselfafterapowercutIfyouarenotcomfortableworkingwith electrical equipment get a qualifiedelectriciantofittheswitchforyou

StaywiththeLathe

Nevereverwalkawayevenforamomentwhilethelatheyouare using is switched on Switch it off if you are leaving itunattended and only leave the lathe after it has come to a

completestopNeverleavealatheinanunsafeconditionMakesure that you have not left the chuck key in the chuck Thechancesarethatifyouarehalfwaythroughsettingupthelathewhen you return you will forget what you have or have notdoneIfindoubtleaveabignoticeremindingyourselftocheckthatthelatheissafebeforecontinuing

Donotleavethechuckkeyinthechuck

SwitchOffwhenAdjustingtheLathe

Shut off the power supply to the motor before starting anyoperationsrequiringaccesstothelathesuchaschangingtoolsmeasuring work mounting or removing accessories changingspeed and setting up change gears The lathemust be safelystopped Just zeroing a variable-speed drive is not safelystoppingitusethezerovoltsswitchtoswitchthepoweroffaswell

CheckbeforeStartingtheLathe

AlwaysrotateyourworkpiecebyhandtomakesureitclearsthetoolrestsaddleandbedDoublechecktomakesureyourworkis securely clamped in the chuck or between centres beforestartingthelatheBecertainthattheworkpieceturnsfreelyand

isfirmlymountedThespeedofthelathemustbecheckedbeforeturningiton

When turning irregular shapes start the lathe on a low speedandincreasethespeedbyapulleystepeachtimeIfthelatheisbouncingabout lowerthespeedandorbalancethework Ifthe work vibrates stop the lathe and check the reason ThechancesarethatyouarerunningthelathetoofastMeasuringequipment toolingandworkpiecesshouldnotbe

leftona latheastheycanvibrateoff intomovingcomponentsand be thrown around the room Check for loose items on alathebeforeuse

UsetheLatheGuards

NewlatheswillbefittedwithguardsoverthemotorshaftdrivebeltandspindlepulleysTheseguardsshouldalwaysbeinplacebefore using the lathe Any other moving parts should beguardedtopreventanythingfallingontothemovingpartsAlthoughguardsareoften removedbymachinistsprovided

they are constructed from clearmaterials and open and closeeasily theyaddsafetywithout interferingwith theworkbeingdone Guards will at the same time deflect swarf and anycoolantthatisbeingusedGuardsfittedtothelatheshouldnotbe removed while it is in use They should be made fromsuitablematerialandnothavesharpedgesTheyshouldnotberemovedforadjustmentandlubricationofthelatheunlessthisis unavoidable Lathemanufacturers donrsquot usually supply chipguards soaddingoneshouldbeconsideredChipguardswithmagnetic bases are available although they can attract steelswarftothemagnetPutthebaseintoaplasticbagtoaidswarfremoval

UseEyeProtection

Lathes can throw sharp metal chips considerable distancesespecially at high cutting speeds Apart from deep cuts thechipsmay leave the tool red hot cause skin burns and even

burnholes in clothing Youmust use safety goggles or propersafetyspectacleswhileintheworkshopAlwayswearindustrialqualitysafetyglassesfittedwithsideshieldsSpectacleswithoutsafety lenses are not adequate eye protection When theglasses get dirty do not wipe them off as they will becomescratchedWashthemoffunderthetapinstead

TakeCarewhenRemovingSwarf

Do not attempt to remove chips or turnings with your handsAlwaysswitchoff the lathefirstandeitherpull theswarfawaywithalargemetalhookorliftitoffusingapairofglovesIftheswarf is tangled around the lathe untangle it with a pair ofpliersandnotaglovedhandasitwillcutstraightthroughtheglovesandintoyourhandUseadustpanandbrushtoremovesmall chips and swarf from the swarf tray ndash never use yourhandsWhenswarfbecomesstringyandbuildsuponthetoolortoolpostturnoffthelathebeforeremovingit

AvoidLooseClothing

IfyouarenotwearingoverallswearshortsleevedshirtsorrolllongshirtsleevesabovetheelbowsLoosesleevescancatchonrotatingworkandquicklypullyourhandorarmintothe latheObviously though keep your arms protected if hot swarf isflyingaroundSwarf can get inside protective clothing especially collars

(useaclothespegtokeepyourcollartight)pocketsandshoesTostopthesleevesofanoverallcatchingsewelastic intothecuffsorwrapacoupleofthickelasticbandsaroundthecuffstostopthesleevesgettingcaughtupUnder no circumstances wear a necktie when operating a

latheProtectiveglovesshouldneverbewornwhileoperatingalathe Protective gloves may be worn when swarf is beingremovedbuttheymustberemovedbeforeswitchingthelathebackon

UseSturdyFootwear

WearsteeltoecapsafetybootstheyarenotexpensiveandwillhelptoprotectyourfeetfrominjuryifyoudropaheavyobjectonthemThelsquotrainerrsquoversionisparticularlycomfortableDonotallow stringy swarf to fall on the floor as youwill get cuts onyouranklesandmayeventripoverit

AvoidJewellery

Do not wear wristwatches rings or jewellery when in theworkshop as it could catch on a rotating part of the lathe orworkpieceThisalsoapplieswhenmovingalatheintooroutoftheworkshopsincetheycouldcatchona falling lathe IfyourotherhalfcomplainsthatyouhavetakenoffyourweddingringexplainthatyouwouldnrsquotbeabletowearitagainifyourfingerismissingduetoanaccidentLonghairshouldbetiedbackasyoucouldbepulledintothelatheifitgetscaughtintherotatingwork

LiftingintheWorkshop

Back injuries can be caused by incorrect lifting practices It isimportant to bend your legs when lifting rather than bendingyour back A hoist or engine lift should be used to lift heavyitems A stool in theworkshopwill take the pressure off yourlegs and will provide a welcome break after you have beenstoodatthelatheforawhile

Self-ignitingMaterials

If you machine titanium or magnesium which can ignite andburn vigorously keep the accumulation of turnings to aminimum If thematerialdoescatch firedonrsquotusewaterorawater-based coolant as an extinguisher since it will makematters much worse Before starting to machine titanium ormagnesiumfillalargebucketwithdrysandcoveritandkeep

it by the lathe The sand will smother the flames veryeffectivelyYoucouldalsobuyoneofthespecialfireretardantsusedinindustryBeware also of grinding aluminium on the bench grinder

Aluminium and steel filings are the ingredients of Thermite apowerful explosive that can also burn If you grind aluminiumandthenchangeovertogrindingsteeltheredhotsparksareliable to set the steelaluminium mix on fire This is a verydangerous combination ofmaterials and should be avoided atallcosts

SafetywithBarStock

Bar stock should be contained within the headstock and notallowed to protrude from the rear of themandrel I once sawsomeone switchona lathewhenabrassbarwas stickingoutfrom the back of the headstock by about two feet With thelathe running at 2000rpm the bar whichwas aboutfrac34in (19mm) in diameter was bent at right angles and caused theheavy lathe which weighed 1280kg to jump about Luckilysomeone managed to switch the lathe off before any majordamageoccurredItwasnottheoperatorhehadrunwellawayandwasnowheretobeseen

SomeFinalWordsonSafety

Wherever possible the machine height should be adjusted tosuittheuserWearestillusingfifty-year-oldmachinesbutfiftyyearsagothenationwasshorterTheworkplaceshouldbeprovidedwithuniformlightingthat

gives an adequate level of illumination Individual machinelightsarebestThe lathemust be set to operate at the speeds and feeds

recommended for thespecificmetalbeingturned If themetalrotatestooslowlyortooquicklyorthefeed istooslowortoofastaccidentsarelikelytooccurThe area directly in front of and behind the workpiece is

known as the lsquofiring zonersquo or the lsquored zonersquo This is where apiece of work is likely to go as it leaves the lathe Make it ahabit to keep clear of this zone when you turn the lathe onLearnwhere theNoVolts switch is as youmightneed to turnthelatheoffquicklyByfollowingalltheaboveadviceyoushouldnowbeableto

worksafelyfullyawareofanysafetyproblemsthatmightariseAtthispointyounowknowhowtoinstallthelathelookafter

itclean itandmaintain it InChapter3wewill lookatcuttingtoolsandexaminehowtoselectcuttingspeedsandfeeds

Thisbarisstickingouttoofarfromthebackofthelathe

3CuttingToolPrinciplesFeedsandSpeeds

The first part of this chapter will look at the materials fromwhichcuttingtoolsaremadeaswellastheirbasicshapeandgeometryWewill thenconsider selectingsuitablespeedsandfeeds

MAINTYPESOFTURNINGTOOLS

There are three main types of turning tool used in modernworkshops HSS (high speed steel) tools carbide brazed-ontoolsandinsertedtiptoolsAllhavetheirusesintheworkshopandformost jobsthere isnopreferenceforonetypeovertheothersTherearealsocarbonsteeltoolbitsalthoughinpracticetheyarejustaboutobsoleteCarbonsteeltoolscanbemadeinthe homeworkshop but apart frombeing used tomake formtools(seeChapter11)thereaderisunlikelytousethismaterialfortools

Ageneral-purposeHSSturningtoolsuitableformildsteel

HSSTOOLS

HSStoolscanbepurchasedsinglyorinsetsalreadygroundtothecorrectshapeIt ischeaperhowevertopurchasethemassquare tool blanks in various sizes ready for you to grind toshapeThecompleteready-groundsetswillprobablycomewithseveralshapesincludedthatyouwillneveruseIfyoucanbuyafewready-groundtoolscheaplytheywillbeofuseasguidestoseehowtosharpenyourownHSStoolblanksHSS form tools from industry are often available second-

handTheseareespeciallygroundtomachineacomplex formall in one go You can often find some that are ground to asuitable shape to form the end of a threaded componentincludingtheundercut

HSSformturningtools

Brazed-onCarbideTools

Brazed-on carbide-tipped tools are quite useful especially forfacing and boring cast iron but they really need a diamond-facedgrindingwheeltokeepthemsharpCarbidetipsandtoolscomeinvarioussizesandhardnesstosuitindividualmaterialscarbidetoolsforsteelwilloftenbepaintedbluethoseforcastiron are painted red and those for stainless steel are paintedyellowThecolourindicatesthesuitabilityofthetoolforcertainmaterials

Brazed-oncarbide-tippedtoolscomeinvariousgradesshapesandsizes

InsertedTipTools

InsertedcarbidetiptoolsareveryusefulbuttheyarenotcheapThe tipsarenotusually sharpenedafterwearingout you justthrow the tip away and fit a new one Most modern carbide

inserts however do have more than one cutting facesometimestheyhavetwoandoccasionallyfourormorecuttingedgesareavailableYoucanevengetformturningtoolswheretheinsertisroundandcanberotatedafull360degrees

Theleft-handtoolisblueindicatingitisformildsteelwhiletheright-handtoolisredindicatingitisforturningcastiron

Some diamond-shaped tips can be used in different toolholders two edges are used in one tool holder and the othertwoedgesareusedinanothertoolholdersoyougettwicethelifepertipInserted tip tools are available for internal and external

screwcuttingwherethetipsareheldat thecorrecthelixangleofthethreadinthetoolholderThedrawbackisthecostofthetipsandeachsizeofthreadusuallyneedsitsownsizeoftip

Aninsertedtipcarbideturningtool

Carbidegroovingtools

InsertedtipgroovingtoolsareidealformachininggroovesforOrings and circlips Theyare available inmany standardwidthsandcanoftenbeusedasparting-offtoolsforsmallerdiametersOneof themostusefulgrooving tools forsmallersizegroovesandpartingoffistheMiniThinsystemassoldbyMSCIndustrialSupplyCo

TheMiniThintoolholderisidealforgroovingandalsoforpartingoffsmalldiametersTheshankissostrongcomparedwiththecutbeingtakenthatusinganoverhangasshownisquite

safe

Coatingstoreducetoolwear

Tipsarealsoavailablewith various coatings that improve toollifeThemostcommoncoatingistitaniumnitride(TiN)whichisgold in colour Other coatings that offer slightly better wearresistancearetitaniumcarbonnitride(TiCN)whichisbluegreyincolourandtitaniumaluminiumnitride(TiAlN)whichisvioletbronzeReady-groundHSScuttingtoolssuchasdrillstapsandreamers are also available with these coatings but once yousharpenthecutterthecoatingisgoneTipped toolsneedadeeper cut ahigher feedandahigher

speed than HSS tools Thismeans that the lathe needs to bestrongrigidandhaveamplepowertodrivethe lathemandrelwhen taking a heavy cut this rules out using tipped tools onlathessmallerthanabout2in(50mm)centreheightSmaller tools are made to fit the Unimat and similar small

lathesbutthesemachinesjustdonrsquothavethepowerneededtodrivethemAtbesttakingacutwillstopthelatheatworstthetoolwillchip

Insertedtiptypes

Inserted tip tools come in many shapes and sizes Some tipshapes and sizes are made to an international standard andothers are to the makerrsquos own standards Wherever possibleuse ISOstandardtoolsas thetipswillbe interchangeablewiththosefromothermanufacturersandwillprobablybecheaperaswell The ANSI system commonly used in the USA is notcompatiblewiththeISOsystemusedintherestoftheworldIfyour lathe ispowerfulenoughyoucantakeadvantageof

insertedtippartingoffbladesThesearemounted inaspecialtoolblockandthebladecanbeslidinoroutdependingonthediameteryouarepartingoffThebladecarriesan inserted tipspecially designed for parting off There are three types of tipavailablesquare-endedtipstipsthatareangledtotheleftand

tips that are angled to the right Square tips are used forgeneral parting off tips angled to the left are usedwhen youdonrsquotwanttoleaveapiponthebackendoftheworkandtipsangledtotherightareusedwhenyouwantacleanfaceonthefrontoftheworkThe parting off blade is oftenmounted upside down at the

backofthe lathecrossslideTheactionofpartingofftendstolift the whole cross slide slightly and forces the cross slidetightly into thematching dovetail whichmakes itmuchmorerigidIfthepartingofftooldigsinwhileinthebacktoolpostthetool tends to lift and push away from the work whereas in afronttoolpostthetooltendstodiginandpullintothework

Simplifieddiagramofpartingofftoolangles(A)straightpartingtool(B)angledtotheleft(C)angledtotheright

POWERREQUIREMENTS

Whenturningmildsteelorstainlesssteelwithanycarbidetoolthe machine horse power required is considerably more thanthat required forordinaryHSStoolsThe twomain reasons forthisarethatcarbidetoolsoftenhaveanegativerakeangleonthecuttingedgeasthistypeofedgelastsmuchlongerthanapositiveangle especially for intermittent cuts andbecause in

industrial use carbide tips are called on to remove largerquantitiesofmetalathigherspeedsandfeedsFor guidance on using tipped tools in the small workshop

wheretimeisnotasimportantasinanindustrialenvironmentIwould recommendusing twice the speedused fornormalHSStools and a fine feed of about 0002in (005mm) per rev as astarting point This can be adjusted up or downdepending ontheresultsThemaindifferencebetweenHSStoolsandcarbidetippedtools(eitherbrazed-onorinsertedtip)isthehorsepowerrequirementofthemachineinuse

Thispartingofftoolismountedatthebackofthelatheinaspecialbacktoolholder

SELECTINGTHECORRECTSPEEDSFORDIFFERENTMATERIALS

Overmanyyears through trialanderror cuttingspeedshavebeendeterminedthatgiveanoptimumtoollifebalancedwithadecent surface finish These speeds are normally quoted inlsquosurfacespeedinfeetperminutersquoSpeeds and feeds used on industrial machines where the

primary tools will have inserted tips will be a lot higher than

thoseusedinthesmallworkshopwhereHSStoolsarethenormThe accompanying table gives an idea of the speeds that

shouldbeused forvariouscommon typesofmaterial likely tobefoundintheworkshopThespeedslistedshouldbesuitableforbothturninganddrillinginthelatheForreaminguseabout25percentoftherecommendedspeedsThe table is a guide only and it is likely that the machine

speedsavailablewillnotbeexactlythoserequiredandyoumayhavetoresorttolsquonearenoughisgoodenoughrsquoSetthelathetothe nearest speed lower than indicated in the table for thediameterandmaterialbeingcutThiswillbefineforHSStoolsDouble the recommended HSS speed for carbide tools For

parting off use about 30 per cent of the recommended HSSspeed For form tools use about 50 per cent of therecommended speed for the initial cuts and then engage thecorresponding back gear (just switch to back gear leaving thebelts on the same pulley) and gently tap the handle until itreachesthefinishedsizeandallowittofinishthecutbyitselfYou may have to adjust the speed down if you get a lot ofchatter

Forturningcastironuseacarbide-tippedtoolrunningattheHSSspeedtoremovetheskinYoucanthenfinishtheturningwithaHSSsteeltoolifyouwishPlease remember if doing any work that might be

unbalancedstartoffslowlyandincreasethespeedabeltstepatatime

THEACTIONOFCUTTINGTOOLS

Basicallya lathe tool isawedge that is forced into theendofthe rotating bar to remove metal As long as the tool is fedforwardwhilethelatheisrotatingmaterialwillberemovedA typical right-hand turning tool has a cutting angle of 90

degreeslessthesideclearancelessthesiderakeThecuttingangle for this example is 90ndash10ndash10= 70 degrees This is theangle that is wedged into the work to remove the materialSoftermaterialswillhaveasmallercuttinganglewhilehardermaterials will have a larger cutting angle Tool angles varydependingonthetypeofmetalbeingturnedToolsforturningsofter metals usually have higher rake angles than thosedesigned for harder metals since a turning tool will normallyholditsedgeforlongerinsoftermaterialsBrassalthoughsoftusuallyhasnotoprakeonthetoolatallOther angles to be aware of are the top rake and the side

rake

CUTTINGTOOLSHAPES

The followingaresomeof thedifferent shapes thatyoumightfindusefulforgeneralturningandmetalremoval

Right-handknifeturningtoolAllrakeanglesare10degrees

Right-hand knife tool This is used for general turning andfacingofbarstockDependingontheworkyouaredoingyoumayfindaleft-handversionofthistooluseful

Typicalroughingtool

Right-handroughingtoolIthasaleadingangleandasmallradius on the tip of the tool This tool is used for fast metalremovalwherefinishisnottooimportantAgainyoumayfindaleft-handversionusefulAroughingtoolcuttingatanangletoabarwillremoveachip

widerandthinnerthanatoolcuttingat90degreestothebarThis improves tool life although you will have to square theturningupwithastandardknifetool

Typicaldouble-sidedroughingtool

Double-sided roughing tool It can turn towards the left orright It canalsobeusedasaplunge tool to removematerialfroma groove orwhere the component needs to be lsquowaistedrsquodown

Simplepartingofftool

Simple parting off tool This is suitable formostmaterialsYouwillprobablyneedalargeoneforpartingofflargediameterbarsaswellasasmalloneforpartingoffsmallcomponents

Internal(top)andexternal(bottom)screwcuttingtools

ScrewcuttingtoolThisisusedforcuttingscrewthreadsTheanglewilldependonthethreadyouarecutting60degreesformetric55degreesforWhitworthandBSFetc

Shallowboringtoolcapableoffacingacrossthebottomofahole

Boring and facing tool This toolrsquos unusual shape will befound very useful when recessing a large bore It will plungestraight intoasmalldrilledholeandwillalso face rightacrossthebottomoftherecess

Double-endedchamfertoolchamferingadiameter

Double-ended chamfering tool It has 45 degree angles atbothendssoitcanbeusedtochamferexternaldiametersandinternalbores

Double-endedchamfertoolchamferingabore

Othershapescanbeusefulbutthetoolsshownhereshouldbesufficienttogetyougoing

BORINGTOOLS

Boring tools are used to clean up a previously drilled holepossiblytomakeitruntruebutmorelikelytoensuretheholeistothecorrectsizeTheyarenormallylongerthanordinarytoolsandtendtostickoutfurtherfromthetoolholderHSStoolsaresuitableformostusesCarbideinsertedtipboringbarsarealsoreadilyavailableandarethebestbetforturningcastironinthesmallworkshop

HSSboringbar

For really small holes down to2or3mm indiameter solidHSSandcarbideboringbarsarereadilyavailableAlthoughtheyarenotcheaptheywillbefoundveryusefulandquicktouseAnothermethodofboringahole is tousea longseriesslot

drillasaboringtoolInuseclamptheshankinthetoolholderwiththepointatcentreheightmakingsuretherestoftheslotdrillisclearofthesideoftheboreYoucanthenrunitthroughtheboreinasimilarmannertoastandardboringbar

Asmallcarbideboringbarinsertedintoamildsteelshank

PARTINGOFFTOOLS

PartingofftoolsprovideaquickwayofcuttingoffworkfromtheparentbarThereisrarelyanyneedtoworryaboutcuttingthecomponentofftothecorrectlengthtogetagoodfinishAslongasthecomponentislongerthanrequireditcanbeputbackintothe chuck or a collet and the parted off face can be faced tolengthorotherwiseworkedonThepartingofftoolcuttingfacecaneitherbesquareoritcan

beangledtotheleftorright(seepage43)Thesideofthepartingofftoolcouldevenberadiusedsothat

it forms a radius on the end of the next component orchamferedtoformalead-inedgeforthenexttool

CUTTINGLUBRICANTS

Tomake cutting tools cut easily and to prolong their life it issometimesbesttouseacuttinglubricantForsteelIpreferneatcuttingoilItlubricatesbutisnotidealforcoolingtheworkIn industry coolant is normally used This is oil that has an

additivetomakeitsolubleinwaterMostsolubleoilswilldobutthe synthetic ones tend to sting your hands if you have anyopen cuts I would not recommend using soluble oils on thehome workshop lathe as I think they tend to wash thelubricating oil off the slideways and can encourage rustHowever this ismypersonalpreferenceandmanypeopleusesolubleoilinthehomeworkshopwithoutanyproblemsOil is suitable for use when cutting steels mild steels

stainlesssteelsandhighcarbonsteelssuchassilversteelThebestlubricantwhencuttingaluminiumisparaffinItstops

thealuminiumfrombuildinguponthecuttingtoolBrassandcast ironarenormallycutdryWhenturningcast

ironona lathe if the latheisfittedwithasolubleoiltankthecastirondustwillhaveanaffinityforthesolubleoilIfthelatheisthenusedonaluminiumthefreecarboninthecast ironcancontaminatethealuminiumwithblackstreaks

Inormallyplacetheoilorparaffininasmalldish(actuallyacatordogfoodbowl)andapply itbyhandwithasmallbrushThisdoesallIneedThenextchapterlooksatgrindinglathetools

4SharpeningToolsandHoldingThemintheLathe

ThenexttaskistogrindasetofusefullathetoolsThe first thing you will need is an off-hand grinder The

grindercanbeadangerousmachineso itshouldbeusedwithcare Eye protection must be worn the guards should becorrectlyfittedandtheremustbeadequateilluminationIdonrsquotlike using a grinder in a small workshop as the grinding dustflies everywhere and canget onto themachine slideways andtools generally making the workshop dusty and dirty Ifpossible set up thegrinder in a separate areaaway from theworkshopIhavemygrindermountedonafoodchoppingboardso I can carry it outside to use This has the addedbenefit ofdaylight although you are dependent on the weather or youmightneedtouseitafterdark

Theguardofthisoff-handgrinderhasbeenwidenedtoacceptarecessedwheel

GRINDINGWHEELS

IthasalwaysbeenstatedthatyoushouldnevergrindatoolonthesideofthegrindingwheelSofollowingthistheorywewillbeusingarecessedwheelwhereitswidthismuchthickerthanthepartofthewheelusedtoclampthewheeltothegrinderIstruggledtofindarecessedwheelof6in(150mm)diameterandfinally found a 60 grit grinding wheel on a personal visit toAxminster Power Tools in Devon (I could find only an 80 gritwheel in theircatalogue)Thewheels I like touse forgrindingare A60K5V if I can get them and I prefer the white wheelsdesigned for the harder tool steels rather than the grey orbrown wheels which are more suitable for softer mild steelsThedesignationbreaksdown like thisA stands foraluminiumoxide 60 is the grit size K is the hardness (I J and K beingmediumhard)5 is thestructure(thespacebetweengrainsofgrit) and V is for vitrified the method of bonding the grainstogetherTheKandthe5canvaryabiteitherwayandthegrit

shouldbe4660or80with60beingpreferredThe80gritisabitfineandwillclogupquitequicklySo-called green grit wheels made from silicon carbide are

available for sharpening carbide tools They are usually softerthanaluminiumoxidewheelsinordertoallowthegrittobreakdownbeforethewheelbecomesglazedfromgrindingthemuchhardercarbide

Witharecessedwheelyoucancutontheouterfaceoftherecessedsideofthewheel

TestingtheWheel

The first thingyoushoulddowhenbuyingawheel is tomakesurethat it is ratedatasufficientlyhighspeedfor thegrinderon which it is to be used Off-hand grinders usually run ataround2900rpmsoyouwillneedawheelratedtoatleastthatspeed it is all the better if the grinding wheel is rated at ahigher speed than the grinder Care should be taken whenhandlinggrindingwheelsastheyarequitefragileifknockedordropped A grinding wheel should only be purchased from areputableengineeringsupplierSupportyourgrindingwheelona piece of wood and tap the wheel gently with a plasticscrewdriver handle or similar The wheel should lsquoringrsquo if itsoundsdullitshouldbebrokeninhalfandeitherthrownawayorusedontheworkbenchasasharpeningstoneNeverthrowawheelawaywithoutbreaking it into twoyouneverknowwho

mightgettheirhandsonit

Thistoolrestwasdesignedtosharpenplaneironsandchiselsbutitisfineforlathetools

Amoderndigitalanglegaugeisidealforsettingthetoolrest

MountingtheWheel

The wheelrsquos bore should be the same as the spindle of thegrindingwheelOften theborewillbe largerandyouwill then

need some plastic spacers to reduce it Spacers should bereadilyavailable fromyour localengineeringsupplierYoucanturn thespacers fromplastic if youcanrsquotbuyany ready-madeonesAt each side of the wheel you should fit a paper washer

thesearemadeofblottingpapertypematerialandwillprobablyhave been supplied already stuck on the wheel The grindershould have twometal flanges one to fit at each side of thewheel Both flanges should be the same diameter These willhold the wheel true and spread the tightening load on thewheelThegrinderwillhavetwodifferent threadsontheendsof its spindle The right-hand side of the grinder will have aright-hand thread and the left-hand side will have a left-handthreadThedifferentthreadsaretostoptheclampingnutsfromunscrewingwhenthegrinderisrunningTofitthewheelremovetheguardandundothenutRemove

the metal flange and then the wheel Make sure the flangesdonrsquothaveany remainsof theoldpaperwasheron themPutthenewwheelontothegrinderspindle(rememberthespacerthepaperwashersandtheflangesateitherside)andscrewthenuthand-tightFinallyholdthewheelgentlyandgivethenutapinchupwithaspannerYoudonrsquotneedtoover-tightenthenutjustsufficiently tostop thewheel fromcoming looseRefit theguard and spin thewheel by hand to ensure it is not rubbinganywhereNowwearealmost ready to switch thegrinder onBeforedoingsohoweverputonyoureyeprotectionandstandtoonesideofthegrindersoyouarenotinlinewiththewheelshould it burst Then switch the grinder on All should be fineandthewheelshouldberotatingsafely

TOOLREST

Theworkrestsuppliedwithanoff-handgrinderisusuallyjustabitofbentsheetmetalboltedonItisusablebutonlyjustI recently purchased a ready-made tool rest as a basis for

makinganimprovedgrindingrestThiswasoriginallydesigned

forsharpeningplanebladesandchiselsforwoodworkingbutitmakes an ideal rest for sharpening lathe tools It is made ofaluminiumandisfullyadjustableforangleThebestmethodofsetting the rest to the correct angle is to use a digital anglegauge These are now very cheap and are readily obtainableThepositionoftherestinrelationtothegrindingwheelcanbeadjusted on its sliding base Many designs for tool rests havebeenpublishedandyoucouldmakeoneofthoseinsteadifyouwishtosavemoneyThetoolclampassupplied isdesignedtoclampplane irons

andchiselssothisneedstobechangedLathetoolsneedtobepresented to the grinding wheel at the correct angles If youdonrsquot have a digital angle gauge this can be achieved usingsimpleguidesmadefromanglesheetmetalandsomescrewsIused gauge plate made from a high carbon steel with anaccurategroundfinishthatcanbehardenedandtemperedbutmild steel would be perfectly suitable if you donrsquot have anygaugeplateavailableYouwillfindaprotractorusefulyoucangetasteelonewith

an adjustable blade for a reasonable price The protractorwillbeusedtosetthetoolanglethatisgroundonthetools

Sheetmetalprotractorsareavailableverycheaply

LATHETOOLGEOMETRY

LathetoolsneedtobegroundtocertainanglesbuttheanglesdonrsquothavetobeexactFormosttoolssomewherehandywilldounless you are grinding a form tool to a particularly accurateshapeIthasbeennormalforbookstoshowtheanglesontoolsas used in a production environment where tools will ideallyhavealonglifeoftenthislifeiscalculatedaslastinganeight-hourshiftsothetoolonlyhastobesharpenedandresetonceadayInthehomeworkshopwecan increasethesecuttingangles

andgetbettercuttingattheslightexpenseofshortertoollifeWehavealreadyexplainedtheshapesof the tools thatyou

willfindmostusefulToolanglesareknownbytechnicaltermstop rake front rakeside rakeandback rakeThe rakeanglesvary depending on thematerial to bemachined but a set ofstandardtoolswillgetyoustartedSomeoftheaccompanyingphotographsareactuallyoflarge-scalewoodenmodels

Theleft-handtoolissuitableforbothfacingandturningtheright-handtoolissuitableforturningonly

Left-handsideofthefacingandturningtoolshowingthefrontandtoprake

Topofthefacingandturningtoolshowingthefrontandsiderelief

Left-handsideoftheturningtoolshowingthefrontclearanceandthetoprake

Topoftheturningtoolshowingthefrontandsideclearanceandthetoprake

GRINDINGATOOL

WhengrindingHSStoolstrytokeepthemascoolaspossibleIfan HSS tool becomes too hot and is then quenched in waterminutecrackswillformonthecuttingedgesThesecrackswillmakethetoolcuttingedgebreakdownveryquicklywhenusedThe best practice is to grind a little bit off the tool and thenquenchitwhileslightlywarmDonotletthetoolgethotdipitin thewater little andoften This should ensure the tool edgedoesnotbreakdowninuse

GrindingYourFirstTool

Most angles can be ground by using the tilting table whileothersmayneedtobefixedinrelationtotheperipheryofthegrindingwheelThefrontandsideofthetoolcanbegroundbytippingthetableatthecorrectanglewhereasthetoprakecanbegroundontheperipheryofthewheelThegrinder should first be switchedoff andunplugged Set

thetoolresttotherequiredangleusingthedigitalanglegaugeoranangletemplateandtightenuptherestBefore switching on the grinder ensure that everything is

freetorotatebyspinningthegrindingwheelbyhandIf all is well put on your safety glasses and switch on the

grinderPlacethetoolonthetoolrestupagainstthesideoftheprotractor Slide the tool along the table until it reaches thegrindingwheel andmetal starts to be removed Slide the toolbackwards and forwards slowly along the restwhile putting alittle light pressure on the tool so that it continues to pressagainst the grinding wheel When you have removed a smallamountofmaterialcoolthetoolbitdownAtnotimeallowthetool bit to get hot Continue grinding until you have removedsufficientmaterialfromthetoolbit

Thegrindingrestissettothecorrectangleof10degreestogrindtheendofthetool

Grindingthefirstangle

TurnthetooltotheotherangleanddothesamesothatnowboththefrontandsideclearanceangleshavebeengroundThis toolwill be enough for brass but for steelwe need to

grindthetoprakeWhengrindingthetoprakeonaright-handtool the slide rest needs to be higher than the centre of thegrinding wheel so that it grinds the tool at approximately 10degrees

Thefirstanglehasbeenground

You have now ground your first lathe tool The tool asreceivedfromthegrinderwillbetooroughtousehoweversoyouwillneedtohonethecuttingedgesYoucandothisonanoilstone(usedwithfineoillike3in1)orwithadiamondlaporusing a combination of the two Lightly lap the front and sideclearanceanglesuntilyougetagoodfinishand lightlyhoneaverysmallradiusonthetipofthetoolFinallyhonethetoprakeangleandyourtoolisreadyforuse

Grindingthesecondangle

Thesecondanglehasbeenground

AllofyourHSSturningtoolscanbedoneinthiswayOnlytheangleswillvaryandthesecanbesetusingadigitalanglegaugeandprotractorAnoccasionalhonewillresharpenyourtoolsaslongasyoutreatthemwithcareA similar range of HSS tools and a parting off tool all with

zero top rake shouldbeavailable if youwill be turningbrassUnless you are doing quantity production one tool holdershouldbesufficientforbrassAsatoolforbrasshasnotoprakeandyouwouldnotnormallygrindthetopawayaslongasyoubuy tool steel of the same size the tip height will remain thesameYoucanthenusethedifferenttoolsinoneholderwithouthavingtoresettheheight

MACHININGCASTIRON

Carbide-tippedtoolsareidealformachiningcastironAsimplebrazedupcrankedtoolwithasmallchamferonthenosewilldoforbothturningandfacingcastironcomponentsThemainuseof this tool will however probably be truing up the faceplatethat comes with the lathe The large diameter combined withtheintermittentcutovertheboltgrooveswoulddestroyanHSStoolinafewsecondsAsmalltippedboringbarwillbeidealfor

taskslikeboringcastironcylinders

Grindingthethirdangle

Asimplediamondlap

Thethirdanglehasbeenground

Tosharpentippedtoolsyouneedadiamondwheelorifyouwant to remove large amounts of carbide a silicon carbidewheeloftencalledagreengritwheelowingtoitsusualcolourSilicon carbide wheels are much softer than aluminium oxidewheels as they need to break down faster to present newsharpergrainstothecarbidetoolAdiamondwheelisonlydesignedtolightlylapatippedtool

itisnotsuitableforremovinglargeamountsofcarbide

Diamondcupwheel

TOOLHOLDING

Smallerlathessuchasarefoundinmostworkshopsmayhaveatopslidewithatoolclampforindividualtoolsablockwithasingle slot to take the tool a four-way turret (or sometimes athree-way)oraquick-changetoolblockandholdersetThereisalsotheso-calledAmericantoolpostwhichisaroundbarwitha slot through it and a bolt in the top to clamp the tool ItusuallycomeswithmatchingdishedwasherstoadjustthetoolheightThistypeisnolongerverycommononlathes

Quick-changeToolPost

Themostversatiletoolholdingsystemisthequick-changetoolblockwithmatchingholdersThedrawbackwiththissystemisthe cost of extra tool holders you need quite a few one foreachtoolThequick-changetoolblockmountsonthefrontofthelathe

normallyontopofthetopslide(Blockscanbefitteddirectlyon

thecrossslidebytheuseofaraisingblocktoaidrigidity)

Quick-changetoolblock

Each holder is set up with its own particular tool The toolholderscanbe individuallysetso that the turning tool isdeadoncentreheightandispresentedcorrectlytotheworkpiece

Quick-changetoolholder

Quick-change tool holders are available with a straight cutslottotakestandardsquareshanktoolholderswithastraightcutwiththeadditionofaVeecut-outinthebottomforusewithroundtoolssuchasboringbarsandasafrontpartingoff tool

holdertotakeahighspeedsteelpartingoffbladeRearpartingoff tool holders are available to take an inverted parting offbladeeitherahighspeedsteelbladeoran insertedtipbladeLeft-handed and right-handed extended tool holders are alsoavailableandmayoccasionallybequiteusefulThetoolblock isnormallymountedonthetopslidebutyou

cangetraisingblockstouseinsteadofthetopslideThismakesthetoolholderblockmuchmorerigidAbackquick-changetoolblockwillneedmountingonaraisingblock

Backofaquick-changetoolholdershowingthedovetailtypeofmounting

Right-handandleft-handextendedtoolholders

StandardtoolholderwithaVeetotakeroundtoolholders

Frontpartingofftoolholder

ToolClamp

Satisfactoryworkcanbedonewithatoolclampedontothetopslideusingshimsteel toset thecentreheightof the toolThemaindrawbacksarethatyoulosethepositionofthetoolwhenyoutakeitoffthetopslidetofitthenexttoolandyoualsolosetheaccuratecentreheightofthetoolunlessyoukeepthetoolandshimstogetherIfyouaremakingonlyonecomponentthisisnotaproblembutitisanuisanceifyouaremakingabatchofmatchingcomponents

Simpletoolclamp

Single-slotBlockToolPost

AblocktoolpostisoftensuppliedwiththecheaperlathesThetoolpostisliterallyablockofmetalwithaslotcutinittotakethe turning tool It is relatively easy to set the tool up at thecorrectcentreheightbyusingvariousthicknessesofshimThisisfineforthebeginnertoturningwhoisjuststartingoutbutitisbesttoreplaceitwithafour-waytoolpostoraquick-changetool post You could of coursemake several block tool postsandkeepeachonesetwithadifferenttool

Four-waytoolpost

Backtoolpost

Four-wayToolPost

Four-wayToolPost

Thefour-waytoolpost isagoodcompromiseona latheasyoucansetfourtoolsintheturretandrotateeachoneintopositionas needed This speeds up production and is a lot faster thanusingasimpletoolclampThedrawback isthatthetoolsstickoutof the turret fourdifferentwaysandyoumightcatchyourhandonasharp toolAsimple ratchetstopensures thateachtool repeats its position when the tool post is rotated so theworkisaccuratelyturnedeachtimethetoolisusedAduplicatefour-waytoolpostwithtoolsforbrasswillspeedupproductionevenmoreCastingsareavailabletomakeyourownthree-waytoolpost The three-way toolposthas theadvantageofbeingable to get close to the work when you are turning betweencentresFor the front tool post I would recommend right-hand and

left-hand roughing tools right-hand and left-hand finishingtools a tool groundup to face barswhile using a half centreand a Mini Thin inserted tip grooving tool with grooving andparting off inserts You will also need large and small boringbarsbothHSSandwithinsertedtipsTheHSStoolsshouldbegroundupforuseasgeneral-purposeturningtoolsformildsteelandsimilarmaterialsThecarbideinsertedtipboringbarshouldbefineforcastiron

BackToolPost

You can fit a quick-change tool block to theback of the crossslideaswellasthefrontSpecialholdersareavailabletotakeaHSSparting off blade or an inserted tip parting off blade Thebladewill be angleddown to give top clearancewhenpartingoffTheseback-mountedtoolblocksareveryhandyastheycanalsobefittedintotoolholderswithafacingtoolorachamferingtoolFor a back tool holder set-up I would recommend an HSS

partingoffbladeafacingtoolforcastironandadouble-ended45-degree chamfering tool that can be mounted parallel with

the chuck or at 90 degrees to it This set-upwill allow you tofaceaworkpiecechamfertheoutsidediameterandortheboreandpartitofftolengthThenextchapterlooksatholdingworkinachuck

5WorkholdingintheChuck

This chapter covers the different types of chucks how to usethemandsetupworkinthemaccurately

Aself-centringthree-jawchuckfittedwithlsquodrilljawsrsquoNotetheexternaljawswhichareinterchangeablewiththedrilljaws

USINGCHUCKS

Themostusefultoolsforworkholdinginthelathearethree-andfour-jaw chucks The three-jaw chuck is usually of the self-centringvarietythistypeofchuckcomesasstandardwithtwosets of jaws The first set of jaws are known as inside or drilljaws as they are most useful for holding round and hexagonbarsTheother setof jawsareoutside jawswhichholdworkusuallyindiscformontheoutsideSelf-centringmeansthatwhenyouinsertabitofbarintothe

chuck and turn the chuck key the chuck centralizes theworkpieceas it tightensup It isunlikely to runperfectly truebutitshouldruntruewithin3or4thouYou can also purchase soft jawswhich are exactly as their

namesuggestsYoucan thenbore themout to fit thework Ifyouborethemonthelatheyouaregoingtousethemontheworkwillrundeadtrue

Asetofsoftjawscanbeturnedorboredtosuittheworktobeheld

Aself-centringfour-jawchuckThesealsocomewithexternaljawsandsoftjawsareusuallyavailable

Self-centring four-jaw chucks can be used for square barsTheyarealsousefulforholdingroundbarswithmoregripthanathree-jawself-centringchuckSoft jawsarealsoavailableforfour-jawself-centringchucks

Afour-jawindependentchuck

Youare howevermuchmore likely to comeacross a four-jaw independent chuck than a four-jaw self-centring chuckIndependent means that the jaws can be moved individuallyand the jaws can also be reversed one two three or four ofthemdependingontheworktobedone

Abaseplatecastinginafour-jawindependentchuck

Wewillfirstlookatthethree-jawchuckThebestmethodofmaking a component in one of these is if possible to turn itcompletely at one set-up If you put a piece of bar into thechuck face the end centre drill drill and ream it skim thediameterandpartitoffitshouldbeconcentricalloverThisisbecausewehaveturneditallatthesamesettingwithouttakingit out of the chuck If we need to machine the other endhoweverwhenwe turn it roundandput it back in the chuckthechancesareitwillnotruntrueThis iswherethe four-jaw independentchuckcomes inYou

canput thecomponent intoa four-jawchuckandset it to runtrueusingthedialtestindicatorAnyworkyoudoonthepartedoff end should then be concentric with the rest of thecomponentWhensettingworkinafour-jawindependentchuckfor a second operation use some thin shimbetween the jawsandtheworkpiecetoavoidmarkingtheworkWorkisoftenheldinafour-jawchuckbecauseitisacasting

anoddshapeorsquareandsowonrsquotfitintoathree-jawchuckIf thework just requires tobe faced flat rightacross the facethereisnoneedtosettheworkrunningradiallytrueItshouldbe near enough on the centre line as long as the work is

reasonablybalancedYou could of course put the component into a three-jaw

chuckbyfittingsoft jawsandmachiningorboringthemouttotake the component This is the best option ifmaking severalcomponentsthatneedtobeidenticalbutifyouonlyneedoneor two components a four-jaw independent chuck will be thequickestmethodofmachiningthemLargerdiameterscanbeheld ina three-jawchuckbyusing

theoutsidejawsThesehavealargeradiusontheinsideofthejaw ifthisradiusis largerthantheworkpiecethejawsshouldnot tend to dig into the work and mark it Outside jaws areuseful forholding components like small flywheels locomotivewheels and chuck backplates when machining the bores ofholesorwhenmachiningacrossthefaceWhenmachining thindiscs it isuseful toputsomepacking

behindthedisctomakeitstandproudofthejawsTostopthepackingflyingoutwhenthemachineisrunningmakeasetofthree or four packing pieceswith grooves at each end and fittensionspringstothemTheyshouldallbethesamediametersothatthebackoftheworkisparalleltothechuckThelengthand grooves can vary slightly as they donrsquot affect theparallelismTheyarequickandsimpletomakesoacoupleofsets of different diameters should find their way intoeverybodyrsquostoolbox

AlthoughmostlathechuckkeyshavesquareendstheyareoftenofdifferentsizesKeepeachkeywithitsownchuck

ChuckKeys

I have alreadymentioned that the chuck key should never beleftinthechuckwhenitisunattended(seeChapter2)PutthekeyintothechuckuseitandputitsafelyawayassoonasyouhavefinishedwithitIfyouswitchonthelathewiththekeystillinthechuckyoumightneedatriptothehospitalDonotuseexcessive forcewhenyou tightenup the chuck

Do not use a piece of tube a spanner or anything else as alever thechuckkeyon itsownshouldbesufficient to tightenthechuckontotheworkWhenusinga four-jawchuckasmallchuckkey littlemore

thanaknurledknobwithasquareoncanbeusedtoadjustthejawsinandoutpriortotighteningupwiththeproperchuckkeyThiswill save timeover adjusting the jawswith a large chuckkeyTo turn the independent four-jaw chuck jaws round a

carpenterrsquosbracewithapieceofsquarebarinittofitthechuckwillmakeshortworkofreversingthe jawsbutdonrsquotuse it forthefinaltighteningasitisliabletostrainthejaws

STARTINGTOTURN

Before going any further you need to learn how to do basicturningFor thisyouneed toput the three-jawchuckonto themandrelStartbycleaningthemandrelwithacleanbitofragorsimilar(Ikeeparollofpaperkitchentowellingintheworkshop)Nowyouneed toclean thechuckrsquosboreand threadusing thetwotoothbrushmethod(seeChapter2)BoththemandrelandthechuckshouldbecleanbeforeyouattempttofitthechucktothelatheSelecting and grinding turning tools has already been

discussed (see Chapter 4) so by now you should have acorrectlygroundturningtoolsuitableforroughingoutapieceofsteelbar

Barwithapiptoolaboveorbelowcentreheight

MakingaToolCentreHeightSettingGauge

Thistoolneeds itscuttingedgesettothecentreheightofthelatheThereareseveralwaystodothisbutoneoftheeasiestiswith a home-made height gaugeWhen starting out this is achickenandeggsituationyouneedtomakethegaugetosettheheightbutyoualsoneedatoolsetatthecorrectheighttomakethegaugeThesimplestwaytoovercomethisproblemistosetthelathe

tooltotheapproximatecentreheightandtakeacutacrossthefaceofthebarDependingonwhetherthereisapipremainingon theendof thebaryoushouldgetan ideahow farout thetoolheightisIfthereisnopipthismeansthetoolisoncorrectcentre height or too high A pipmeans the tool is too lowOfcourse you may have been lucky so try dropping the toolslightly until a pip remains You can then raise the tool a fewthouatatimeuntilthepipdisappearsThetoolshouldthenbeoncentreheight

Barwithnopiptooloncentre

Nowthatthetoolisatcentreheightyoucanmakeasimpleheight gauge Turn a piece of bar down to as close to frac12in(12mm)asyoucangetandleaveitinthelathechuckMeasurefromthetopofthecrossslidetothetopofthebarwithacheapheightgaugeLowertheheightgaugebyhalfthebardiameterTheheight

gaugeshouldbeexactlyonthelathecentrelineMakeanoteofthisdimensionWe now need to look at how to turn a bit of bar to an

accuratediameterWhenturningabartosayfrac12in(12mm)youneedtostartwithsomethingslightlylargerInthiscasethiswillbe⅝in(16mm)diametermaterialasthisisastandardsizeCutapieceofmaterialabout2in(50mm)longandputitinto

thechuckwithabout1in(25mm)stickingoutSkimtheoutsidedown to about 0510 thou or 1225mm which is 10 thou(025mm) above the size required (You should be aware thatmosthobbylathedialsremovetwicewhattheysayaonethoudivisionforexamplewillusuallytake2thoufromthediameterLargercommercial lathesaremuchmore likelytotakeoffonethoupergraduation)Nowtakesmallcutsuntilalmosttosizeusingpowerfeedif

you have it andmaking sure you knock the feed off before ithitsthechuckStopthelatheandwindthecarriagetothestart

of the bar Take another cut at the same setting andmake anoteofthediameterTakeanothershallowcutbutthistimegoonly about frac14in (6mm) along the bar knock the feed off andturn the lathe off Move the carriage towards the tailstock sothat you can measure the bar Continue making this cut andmeasureuntilthesizeiscorrectThenrunthetoolalongthefulllengthof the jobWindthecarriagebacktowardsthetailstockand take a finishing cut or two at the same setting ThediametershouldnowbetheexactsizerequiredIt is not difficult to turn accurately it just takes a little

patienceandpracticeThemoreturningyoudotheeasieryouwill find it is to hold accurate limits If you turn everythingaccuratelywhetheritneedstobeaccurateornotyouwillsoonlearntoturnwithinathouorsowithoutanyproblems

Measuringtheheightofthebarabovethecrossslide

Now we need to make a tool height setting gauge Cut alengthofbarjustoverthedimensionsyouwrotedownandfaceone end turn it round in the chuck and face the other endMeasurethelengthandfindouthowmuchyouhavetotakeoffit to give the dimension you want Put the bar back into thechuck and bring the tool up to the face of the bar Lock thecrossslideFacethebartolengthbyusingthetopslideindexmovingforwardsafewthouatatimeuntiltherequiredlength

is reached Younowhavea tool height settinggauge suitableforthefrontandreartoolsIf you have an inverted Vee bed lathe or if for any reason

youcanrsquotusetheheightgaugeflatonthebedyoucanputtheheightgaugeonaplateon topof the lathebedwhileyouaresettingthetoolheight

Settingtheheightgaugetothelathecentreheight

Settingtheheightofthetool

Usingthesettinggaugetosettheheightofthereartool

TurningtoaSpecificLengthandDiameter

Nowwewill turnabarwithastepon theendToensure thatthestep isthecorrect lengthwewilluseabedstopThiscanbe as simple as a block clamped to the lathe bed to stop thecarriage moving any further I use a simple home-made bedstopthatdoesallIrequireSetthebedstopthenmovethecarriageuntilittouchesthe

stop and lock it Wind the top slide so that the tool is justtouching the end of the bar and lock the carriage For thisexercise we will make the step 16mm long and 12mm indiameterWindthetopslidealong159mmWecannowroughout thestepateachendTurn theenddown toabout02mmabove the finisheddiameterbywinding thecarriagebackandforthYoucanusethe fine feedbutmakesureyouknockthefeed off before the carriage reaches the stop and finish up tothestopbyhandWindthetopslidealongtheremaining01mmto12mmandfinishthediametertosizeandlengthtakinglightcuts as previously Donrsquot forget to clean up the face of theshoulderyouhavejustturnedIfyouneedtouseabedstopatthetailstockendofthelathe

asimplemethodofdoingthisistouseabarplacedonthelathe

bed against the tailstock The bar acts as a stop when thecarriageiswoundbacktowardsthetailstockThistailstockendbed stop is useful when you are turning a groove in acomponentandyouneedstopssetatboth theheadstockandtailstockendsofthelathe

Ahome-madebedstop

TurningWorkontheOutsideoftheInsideJaws

Theoutsideoftheinside(drill)jawsareusefulforturninglargerdiameterwork that is too large to fit inside thedrill jawsThiswillmostoftenbe in the formofa flywheelcastingFlywheelswithsixspokesareidealforturninginathree-jawchuckasthespokes can fit between the chuck jaws Ideally you need totighten up the flywheel until it is tight but not so tight as todistorttherim

TurningasteponabarusingthestopThebarisheldinthethree-jawchuckandsupportedwiththetailstockcentre

Ausefultailstockendbackstopmethod

Holdingaflywheelinathree-jawchuck

Holdingaflywheelintheoutsidejaws

To ensure concentricity you should do as much work aspossibleonthecastingatthesametimeYoushouldbeabletoturntheoutsiderimofthecastingfacetherimfacethebossand drill bore and ream for the crankshaft all at the samesettingAllyouneedtodothenistofittheoutsidejawsreversethecastinginthechucktapitgentlybackontothestepsoftheoutsidejawsandfaceacrossthesecondsideoftherimandthehubUseabitofshimtoprotecttheflywheeldiameterItdoesnotmatter if the flywheel runs exactly true or not as you areonlyfacingitparallelandtowidthnotturninganydiametersto

size

UsingtheSoftJaws

Soft jaws are very useful when a component has to run deadtrue in the jaws for example when making something like agrindingspindlewhereconcentricityisimportantSoftjawslikelytobefoundinthehomeworkshoparesimple

rectangles of steel with the scroll and groove formed directlyintothesoftjawsAnothertypeofjawyoumaycomeacrosshasa grooved pattern in the main jaws that matches a similarpattern in theactualsoft jawsThesoft topsof these jawsareusually interchangeable They are more likely to be found onlarger chucks but you could make your own version for thesmallersizesofchuckifyouwishThemain use of soft jaws is for second operationwork for

examplewhenyouhaveturnedacomponentcomplete fromabitofbarandparteditoffNowyouneedtoholdthecomponenttruetofinishoffthesecondendYoucandothisbyboringoutthechuckjawstotheexactdiameteroftheworkpieceToborethesoft jawstheyshouldbetightened inthesame

direction as they will be tightened in use so that they areoperatingonthesamepartofthechuckscrolleverytimeIfyouhaveathincomponenttomachinefitthesoftjawstothechuckandtightenthejawsontoabitofbarheldinthechuckBesureto leaveenoughspace in frontof thebarsoyoucanbore thejawstofitthework

BoringsoftjawstofittheworkThejawsareclosedontoanoddmentofbartoturntheshallowregistersothatittakesthework

AlwaysusethesamechuckkeyholewhentighteningupthejawsThisappliestoanythingyoudowithaself-centringchuckStampacrossoracentrepopmarkagainstoneof the jaws IsuggestdoingthisnexttojawNo1butanyonewilldoaslongas you always use the samemarked hole Youmight as wellmarkallyourself-centringchucksinthesamemannerCarefullyborethejawstotheexactdiameteroftheworkto

be machined Try to get it exactly on size Undo the jawsslightly remove the bar and replace it with the workpiecewhichshouldnowrundeadtrueAusefulmodificationtothesoftjawsistodrillandtapahole

inthemiddleofthejawsandfitanAllenscrewtoeachholeIfyouwant toholda longbar in thesoft jaws it isnoweasy toboreallthewaythroughthejawsratherthanjustboringastepor part way through All you need to do now is find a disc ofmaterial to put into the chuck ensuring there is sufficientmaterialleftontheinsideedgesofthechuckjawstoborerightthroughtotakethebar

Holdthedisconthescrewheads ifnecessarydrillthediscbeforeboringBorerightthroughthediscandthejawsuntilyouarenearlytosizeatwhichpointyoucanborethroughthediscand test the resultingborewith theworkpieceMakesureyouclean the bore thoroughly before trying the workpiece sinceloose dust can make the hole seem smaller than it really isWhentheworkpieceenterstheborefinishboringrightthroughthe jawsgo througha coupleof timesat the samesetting totakeoutanyspringintheboringbarYoucannowremovethedisc clean the jaws and put the workpiece right through thechuckcheckingthatitrunsdeadtrueThisoperationmaysoundtimeconsumingforasingle item

but if you have several components to make it will save aconsiderable time on setting up each bar individually to runtrue

BoringsoftjawsusingaringThesoftjawshavethreeAllenscrewsthatarecloseddownontotheringwhileboring

TurningtheoutsideofthesoftjawsusingaringThesoftjawshavethreeAllenscrewsthatareopenedupontotheringwhileturning

NowthescrewsareinplacewecanworktheotherwayroundandholdcomponentsontheoutsideofthejawsTodothisyouwillneedaringofasuitablesizeontowhichyoucantightenthejawswith the jaw loading acting outwards so any componentyouputontheoutsideofthejawswillberunningconcentricallyThiswill be ideal for itemssuchas tractionenginewheel rimsandotherlargehollowortubularworkpiecesOne other use for soft jaws is to hold irregular-shaped

components Put a piece of bar into the soft jaws and bore aholeofanysizeand thencleanup theboreso thatallof thejawsare true Transfer the chuck to themillingmachine tableandclampitdownUseatestindicatortocheckthattheholeinthechuckistrueYou can now mill a nest to take any irregularly shaped

component confident that when the chuck is returned to thelatheitwillberunningtrue

Plungertypedialtestindicator

Levertypedialtestindicator

DialTestIndicators

Therearetwomaintypesofdialtestindicatortheplungertypedial test indicator as its name suggests works on a plungerprinciplewhilethelevertypedialtestindicatorhasastylusonthe end The lever stylus is usually ball-or pear-shaped and isfixedtothedialtestindicatorwithafrictionfitmeaningthatitcanbemovedupanddownontheendofthedialtestindicator

throughawidearctoputitintothebestpositionforuseThe plunger type dial indicator usually has a maximum

plungermovementoffrac12in (12mm)butplungermovementsofupto2in(50mm)areavailableTheplungertypedialindicatoris non-reversing and needs an adaptor to enable it to clockholes true Instead of a stylus it has an interchangeable endoften with a ball fitted various interchangeable ends areavailableoryoucanmakeyourownThe lever dial test indicator has a much smaller range of

travelarangeof0008in(02mm)isverycommonItisusuallyeither self-reversing (itmoveswhen in contact with theworkdependingonwhichwayitismoving)oritmaybereversedbyusinga lever on the sideof thedial test indicator both typesarequite commonSince the stylus isdelicate combinedwithitslimitedtravelrangeyoumustbeverycarefulnottobreakitAplungerdialindicatorcanbeusedasadirectreadoutofthe

travel and will be found to be very accurate Owing to therelativelylongtravelifyouwantedperhapstooffsetthecentreofabitofbar in the four-jawchuckby0125in (318mm) thiscanbedonebyturningthechuckbyhandandsettingthebaruntil the indicator travel shows 0250in (635mm) which is0125in (318mm) offset The lever dial test indicator is of nouseforgivingdirectreadingslikethisbutshouldbeusedasacomparatorwherethereadingtakenisforexamplezeroatallpointsofthetravelThedial test indicator is usuallymounted on amagnetic or

vacuum base but is sometimes fixed to a block that can beclampedtothelathemostoftenonthecrossslideSometimesthedialtestindicatorcomesasacompletekitincludingvariousmountingcomponents

Clockingtheendofacastinginafour-jawchuck

Four-jawChuck

To set thework up in an independent four-jaw chuckwe firstneed to know what part of the workpiece should be on thecentre If theworkpiece is a castingwemay have an outsidediameter or a hole that needs to run true in this case wewould put a dial test indicator onto the work and adjust thechuckalittleatatimeuntilthediameterrunstrueDonotturnthe chuck with the indicator in the hole Instead wind thecarriage forwards until the clock enters the hole and take areadingWind thecarriageback rotate thechuck90degreeswindthecarriageforwardandtakeanotherreadingAdjusttheworkinthechuckuntilitrunstrue

WhereacastingisstickingoutashereyoushouldtrytosupportthecastingwitharunningcentreThiswillhelptostopthecastingshiftinginthechuck

LatheCentreFinder

If there isnodiameterorholeyoumayhave tomarkout thecentreontheworkusingaheightgaugeandcentrepopitwithacentrepunchThenyoucanuseawobblerandatestindicatortosettheworktrueItwasoncepossibletogetalathecentrefinderconsistingof

a bar about 6in (150mm) long pointed at both ends with auniversaljointabout1in(25mm)fromthefrontendInusetheshortfrontendgoesinthecentrepopoftheworkinthechuckWhen you rotate the chuck by hand the pointed short endfollows the eccentricity of the centre hole which ismagnifiedaboutsixtimesatthetailstockendYouthenjusthavetoadjustthechuckuntilthetailstockendisrunningtrueatwhichpointthe centre in the work will also be running dead true I donrsquotknow anyone who makes these and second-hand ones areextremelyrare

Asimplehome-madecentrefinder

You can make a simple version of this that works well byusingamillingmachinepointedcentrefinderThisisaparallelbarwithaseparatemoveablepointedendThetwocomponentsare held together with a spring inside You need the pointededge finder a Morse taper parallel adaptor (the Morse tapershould fityour tailstock)aspringandashortstubofbar thatwillfitinsidethetaperedholderrsquosboretostopthespringgoingrightthroughPuttheshortstubofbarintothetaperinsertthespring follow up with the centre and put the Morse taperadaptorintothetailstockBringthetailstocktowardsthechuckuntil the centre of the centre finder is in the centre pop ThespringwillholditinplaceTousetheimprovisedcentrefinderput a dial test indicator onto the parallel part of the centrefinderrsquospointandrotatethechuckbyhandThepointwillrotateeccentricallyadjust thechuckuntil thecentre finderrsquospoint isrunningtrue

Usingascribingblockwithadialtestindicator

Move the tailstock along the bed until the point of thewobblerisinthecentrepopontheworkPutthetestindicatoronthefrontdiameterofthewobblerandadjustthechuckjawsuntilthewobblerisrunningtrueWhensettingupacastingorsomethingsimilarwherenotall

of the diameters are machined you should use the dial testindicator on diameters thatwill not bemachined such as theinsideofaflywheelrimWhenyouhaveturnedallthefinisheddiameters they should then be true with the unmachineddiametersSetting work in the four-jaw chuck depends on the

componenttobemachinedIfyouareusingroundmaterialyoucansetittoruntrueusingadialtestindicatorHoweverifyouaresettingaroughcastingthevariationofsizeandroughnessofthecastingsmaywellbeunsuitableforadialtestindicatorThere are alternativemethods of settingwork up in a four-

jawchuckespeciallyforcastingsOneofthesimplestmethodsis toholdasquarebar in the lathetoolholderandusethis tosetthejobtrueInuseyouwindthebaruptotheworkandsetthedial tozeroorotherwisemakeanoteofwhere it isWindthebaroutorawayfromtheworkTurnthechuck180degreesand wind the bar up against the work again You can

immediatelyseewhichwaythebarneedstomovesothatitisrunningtrueAdjustthecastinginthefour-jawchuckandmovethecastingtowardsthecentrepointRepeatuntilthecastingisrunning true This method is also useful if you are setting asquarebar to run true Justcheckeach faceof thesquarebarwiththebitofmetal

Settingacastingbyusingasquarebar

StickyPinMethod

An alternative the sticky pin method is especially suited tolocomotive wheels or flywheels An ordinary household pin ismounted in plasticine or Blu-tack perhaps stuck on the lathetool and is arranged to point to the inside diameter of thewheelor flywheel thearea that isnotmachinedbut is leftascastAdjustthecastinguntiltheunmachinedfaceisrunningastrueasyoucangetitandthewheelisreadytoturnThestickypinmethodisalsousefulforsettingupworkthathasachuckingspigot such as a locomotive smokebox door Just hold thechucking spigot in the four-jaw chuck and adjust the castinguntilitrunstrueontheoutsidediameterandthefrontface

Usingacommercialstickypintosetworktrue

Themethodsofcentringworkinthefour-jawchuckthathavebeen discussed are also suitable for setting work true on thefaceplate The next chapter looks at turning between centresandusingthefaceplate

6TurningbetweenCentresandFaceplateWork

Thischapterdealswithbasicturningbetweencentresandthenintroduces turning with the work mounted on the lathefaceplate

Headstockcentreanddriverplate(alsoknownasacatchplate)

TURNINGPLAINBARSBETWEENCENTRES

The most basic way of holding work for turning is between

centres Turning between centres is literally holding thecomponenttobemachinedbetweentwocentreseachofwhichhas a 60-degree included angle The headstock centre usuallygoes round with the headstockmandrel although some olderlatheshadanon-rotatingcentreandthedrivetotheworkwasbyapulleymountedontheworkThetailstockcentreisoftenafixedcentrethatdoesnotgoroundalthoughcentreswithballbearingscalledrunningcentresarereadilyavailable

Tailstockplaincentre

The component to be turned usually a shaft has a female60-degreecentreinbothendsthatisusedtosupporttheworkThe work can be turned round between centres so that bothends of the shaft can be machined Because the work ismountedbetweencentresbothendsoftheworkwillbetruetoeachother

Tailstockrunningcentreso-calledbecauseitrunsonballraces

CentringtheBar

FirstwehavetoputthecentresintoeachendofthebarIfthebarisshortsayuptoabout6inlongholdtheworkinthethree-jawchuckanduseacentredrillinthetailstockdrillchucktoputacentre intothebarAcentredrill isashortdrillwithasmallpilot on the end that has a 60-degree taper to the bodydiameterAbettermethodof centring thebar especially longbars is by using a three-jaw chuck and the fixed steady Thebarisheldinthethree-jawchuckwiththeotherendsupportedin the fixedsteadyand thecentre is formed in theendwithacentredrillAusefultoolthatcanbeusedtofindthecentreoftheshaftis

thecentresquarewhichisametalbladewithaVeeonitthatlocatesonthediameterofthebarMarkalineacrosstheendofthebarwitha scriber turn the centre square90degreesandthenscribeanotherlineWherethetwolinescrossisthecentreof thebar Tomake it easier to see the scribed linesblackenthe end of the bar with a permanent felt tip marker beforescribingCentrepunchthepointwherethetwolinescrossandput a 60-degree centre in each end of the bar using a centre

drill in a power drillHold thebar in a bench vicewhile doingthisPutacentredrillintothetailstockdrillchuckandinsertthebar in the three-jaw chuck Make sure the lathe is on a lowspeedabout300rpmwindthetailstockinandjustlightlycleanupthecentreholewiththecentredrilltotrueitupAnotherusefultooltofindthecentreofabarisabellcentre

punchThiscomprisesaconewithacentrepunchinthemiddleIn use place the bell end on the end of the bar and tap thecentrepunchwithahammertomarkthecentreTheendofthebar though needs to be reasonably square if using the bellpunchmethodThere are other similarmethods of centring bars but those

givenherewillbealltheturnerneedstolearn

Turningbetweencentres

Centringthebarusingthefixedsteady(Notethatthefrontclampisnormallydoneupwhileinuse)

Asimplecentresquare

Crosssectionofbellcentrepunch

MachiningtheBar

NowweneedtomountthebarbetweencentresThisissimplyamatterofputtingthebarbetweencentresandtighteningthetailstocksoitislightlypressingintothecentreintheendofthework To drive the work a carrier is fixed to the shaft andengagesapininacatchplatemountedonthelathemandrelAcatchplateissimplyablankdiscwithapinstickingouttodrivethecarrierthat isfittedtotheworkThecarrier isfittedtotheworkusinganAllenscreworboltTostopanymovementofthebarinrelationtothecatchplatethecarriercanbewiredtothecatchplatepinThiswill stop thecarrierand thework flappingaboutItisparticularlyimportanttostoptheworkfrommovingin relation to the catchplate when screwcutting betweencentres

Facingoffabarusingthehalfcentre

Nowthatthebarissafelymountedbetweencentreswecanstart turning it tosizeNormally the first thing todo is to facetheendsofthebartothefinishedlengthDecidewhichendofthebarhastheshallowercentreWewillmachinethisendfirstYouwillneedahalfcentreso-calledbecausealmosthalfofthecentre is missing This means the lathe tool can reach rightacrosstheendoftheworkwithouttouchingthehalfcentreWhenusinganyfixedcentreinthetailstockputabitofoilor

grease into the centre before use and top up as necessaryLightlywindthetailstockbarrelagainstthecentreandlockthebarrel so it canrsquotmoveSwitch the latheonandwind the toolacross to clean up the end Reverse the work and clean theotherendupat thesamesettingBothcentresshouldnowbethesamedepthMeasuretheoveralllengthofthebarTakethefinished length required from the overall measurement youhavejustmeasuredDividethisbytwoandthisishowmuchweneed to take off each end of the shaft so it finishes at therequiredlength

Askimmedbar

Ifyouhaveonechangethetailstockhalfcentretoarunningcentre if you donrsquot have a running centre change to a fixedcentreThehalfcentreshouldonlybeusedwhenfacingtheend

of the bar We will nowmachine the rest of the bar For thepurposeofthisexamplewewillassumethebarhasafinisheddiameter in themiddle with a step at each end First we willmachine the overall diameter to size To do this we need toskimthediameterandcheckthesizeTakeafinecutalongthebarusingthefinefeedifyouhaveoneMeasurebothendsofthebar Ifyouhavesetthelatheupcorrectly(seeChapter2)thebarshouldbeparallelIfitisnotadjustthetailstockbeforecontinuingAssumingthebarisparalleltakeanothercutortwosothatyouareabout01mmlargerthanthefinisheddiameterNowmove the tool in until almost at finished size and take alight cut about 10mm long along the bar Repeat this cut toensure the tool is notpushingoffMeasure thisdiameter youwill probablyhave towind the tailstockbarrel back toget themicrometerontotheendofthebarOnlymovethebarrelbackdo not slide the entire tailstock backMeasure the bar to findouthowmuchtoremovefromthediameterTakeanothershortcutandcheckforsizeWhenthebariscuttingtosizemachineall thewayalongYouwillprobablyhave to take twoor threecuts at the same setting until the bar ismachined to finishedsizeNowwewill turn the stepson theends Toensure that the

stepsare thecorrect lengthwewilluse thebedstopSet thebedstopthenwindthetopslidesothatthetoolisjusttouchingthe end of the bar For this exercise we will make the steps12mm long Wind the top slide along until the tool is justtouching the end of the turned bar Wind the top slide along119mmWecannowroughoutthestepateachendTurntheenddowntoabout02mmabovethefinisheddiameterYoucanusethefinefeedbutmakesureyouknockthefeedoffbeforethecarriagereachesthestopandfinishuptotheendbyhandRepeat for the other end Wind the top slide along theremaining01mmto12mmandfinisheachendinthesamewayasyoufinishedthemaindiameterDonrsquotforgettocleanupthefaceoftheshoulderyouhavejustturnedCongratulations you have just turned an accurate shaft

Donrsquotworryiftheshaftisatinybitundersizeyoucanprobably

makethematingholestofit

Thefinishedshaft

Usingachuckandarunningcentre

Usingthemethodsetoutaboveyoushouldnowbeabletoturn any shaft you require within the capacity of the lathe Avariationoftheabovemethodwheretheshaftissingle-endedistoholdoneendinthethree-orfour-jawchuckandsupporttheotherendwithacentreinthetailstock

Alargefaceplatesmalleronesareavailable

FACEPLATEWORK

Another basic way of holding work is on the faceplate Thismethod is used when the component is too large or isawkwardly shaped andwould be difficult to hold in a three-orfour-jaw chuck Usually the work is clamped directly onto thefaceplate often with a packing piece behind it to protect thefaceplateThefaceplateshouldbeflatandtruesothefirstthingtodo

whenyougetthelatheistocheckthefaceplatewithadialtestindicatorCarefullycleanthemandrelnoseandtheinternalholeinthefaceplateMakesurethemandrelcanturnfreelybyhandwith the lathe switched off and check that the face of thefaceplateisrunningtrueasclosetotheouteredgeasyoucanget If it is runningtrue runthetest indicatoracross the frontfaceofthefaceplatethisshouldbetrueaswellIfthefaceplateis running out itwill need to bemachined Put the lathe intobackgear if ithas it (topbackgearwillprobablybe fine)Youwill need a carbide-tipped tool ideallywith a small 45-degreechamferonthetipBringthetooluptothefaceplateand lockthe carriage Next you need to lightly face the faceplate right

acrossitsdiameterIfyouhaveapowercrossfeeditwillmakelight work of this but if not you can feed across by handFortunatelymost faceplateshavea series of rings on them toaid in setting up the work Machine the faceplate from theoutsidetothefirstringandstopforarest feedtothesecondring and so on until finished Depending upon how badly outyourfaceplateisyoumayhavetodothismorethanonceuntilit iscleanedupbutwhen it isdoneyouwill rarelyneedtodothisexerciseagain

Machiningaholeinablock

Asmentionedpreviously the ringsmachined on the faceplateareguidestohelpyousetuptheworkThiswilldoiftheworkisaroundcomponentbutweneedadifferentmethodiftheworkis square Take a block of metal for example that has beenmachinedalloverWewanttomachineaholeinit2infromoneedgeand1in fromanother edgeMarkout thepositionof theholeandcentrepunch it Put adeadcentre into the tailstockholdtheblockontothefaceplatebringthetailstockuptowardsthechuckandlockitWindthetailstockbarrelandcentreuptothe component and engage with the centre pop Lock thetailstock barrel Clamp the block to the faceplate using somepackingpiecesandfourclampsontheblockTheholeisnowoncentreandwecanmachineitinthecorrectplaceIf we need more than one hole placed accurately in the

componentwecanusetoolmakerrsquosbuttonstoensuretheholesare in the correct place Toolmakerrsquos buttons usually come insetsof fourOnebutton isusually longer than the rest soyoucanstillclockthediameterwhenitisclosetoanotherholeSetsare often available second-hand on eBaywhile they probablyhaveanobscureAmerican threadyoucanclamp themto theblock using your own BA or metric screws together with awasher

Settingupthefaceplateusingthetailstock

Asetoftoolmakerrsquosbuttons

Tofitthemtothecomponenttobeboredmarkoutdrillandtap holes in the approximate positions where the holes areneeded If you need a pair of parallel holes place thecomponentonasurfaceplate looselyfitthebuttonsandpushthem down onto a parallel or similar block of the correctthicknessandnipthescrewsupThespacershouldbesmallerthanrequiredbyhalfthediameterofabuttonIftheholesneedtobeacertaindistanceapartuseaspacer

of the correct size between the buttons (Remember tomake

thespacersmallerbyonediameterofthebutton)

Settingupacomponentusingtoolmakerrsquosbuttonstogetafixeddistancefromtheedgeofacomponent

TherearelotsofdifferentwaystosetthespacingofbuttonsItismainlyamatterofcommonsenseCastingsandflatcomponentscanbeboltedtothefaceplate

for machining A typical example of a flat component is aneccentric strap This type of component is usually made of acomponentthatiscutinhalfandboltedbacktogetherAholeisthenboredinitonthecentrelinetofittheeccentricThistypeofcomponentisoftendifficulttoholdinthelathechuckandisprone to distortion Castings are often too large to fit into alathechuckandso the faceplate iscalledon toundertake theworkAcastingcanoftenbebolteddirectlytothefaceplatetofacilitateeasymachining

Settingupacomponentusingtoolmakerrsquosbuttonstogetafixeddistancebetweenthecentresofacomponent

Work on the faceplate is often an odd shape or is set off

centreThiscauses it tobeunbalancedandasaconsequencethe lathemayvibratewhile thework is turningTocounteractthis tendency the faceplate should be counterbalanced byboltingweightsontoitAusefulsourceofweightsisthelathersquoschange wheels By bolting a change wheel or two onto thelightersideofthefaceplateyoucanbringthewholeassemblybackintobalanceAfterboltingthechangewheelsonspinthelathe by hand to check the balance The faceplate should notshowatendencytostopatoneparticularpointWhenyouarehappy that the faceplate is in balance the work and balanceweightsareboltedontightlyandsothattheworkdoesnotfoulthe lathewhen turnedbyhand switch themachine on in lowback gear to check for vibration Depending on what you areturning you should be able to run in top back gear or evenbottomdirectspeed

Asimpleclampsetisveryusefulwhenmachiningacastingonthefaceplate

TurningaFlywheel

Oneofthemainusesofafaceplateisturningalargediameteriron casting typically a flywheel or a locomotive wheel for asteamengineTheflywheelshouldbemountedsothattheinneredgeoftherimandtheouteredgeofthehubruntrueIfeitherofthemrunsoutitwouldbebetterthatthehubrunsoutasthe

rimwillbemorenoticeableonthefinishedengineClamp the flywheel down with some packing under the

spokessothatyoucanturnrightacrosstherimBecarefulthatyouclamptheflywheeltightenoughsothat itdoesnotmovebutnotsotightthatitdistortsRoughturn theoutsidediameterand facetherimusingthe

backgearUsingadirectdrivespeeddrillandborethecentrehole and either finish off with the boring tool or use a reamDonrsquot try reamingwithout boring the chances are that if youdotheholewillnotbetruewiththerimasthedrillprobablydidnotcutanaccurateholeDropdowntothetopbackgearspeedface the rim and turn the outside of the rim to the finisheddiameter Turn the flywheel over and finish the other face towidth

Astubarborsuitableforcentralizingalocomotivewheelorflywheel

TurningLocomotiveWheelFlanges

LocomotivewheelflangescanbeturnedonafaceplateYoucanpurchase blank end Morse taper arbors that fit into theheadstocktaperFitoneoftheseandturnaspigotonittotake

thewheel bore Thewheel bores should all be the same sizebut if they are different sizes machine the spigot to fit thelargestboremachinetheflangeonthatonethenmachinethespigotdowntofitthenextonemachinetheflangeandsoonIdeally the wheel bores should all be the same size but if

theyarenotproceedas followsSkimtheoutsidediameterofthe wheel flangemeasure and take it to the correct finishedsizeMovethelathetoolinbythedepthoftheflangeandturnthe tread Deal with all wheels like this machining all of theflangeoutsidediameterstothesamesizemovinginthecrossslidebythesameamounteachtimesothatallthetreadsendupthesamesize

UsingtheKeatsVeeangleplatetoturnaneccentriccomponent

KeatsVeeAnglePlate

TheKeatsVeeangleplate ismountedon the faceplateand isusedtoholdroundbarsquarebarandmiscellaneouscastingssuch as cylinders and steam chests The angle plate can bemountedanywhereonthefaceplateaslongasthelathecanbe

rotated safely and is in balance When spun by hand thefaceplateshouldnotshowatendencytostopatanyparticularplacewhenrununderpowerthelatheshouldnotvibrateAswellasholdingbarandcastingsforturningtheKeatsVee

angleplateisveryusefulformakingeccentriccomponentssuchastheeccentricsforasteamengineTo turn an eccentric use a test indicator to check that the

roundbarisrunningreasonablytrueWhenthisissatisfactoryyoucanturntheoutsidediameterofthebartofittheeccentricstrap (or component) including any step or groove requiredNextoffsettheKeatsVeeangleplatebytheamountyouwantthe eccentric lsquothrowrsquo to be Use the dial test indicator tomeasure the offset of the outside of the eccentric The offsetshouldbetwicethethrowYoucannowdrillboreandreamtheholeintheeccentricYounowhaveenoughbasic knowledge to carryout turning

between centres andwork accurately on the faceplate In thenext chapterwewill lookat holdingwork in a collet andonamandrel

7ColletsandMandrels

Thischapterexplainsallaboutholdingworkinacolletandhowyou canmake and use several different types of mandrel forworkholding

ERcollets

USINGCOLLETS

Quite a few different collet systems are to be found inworkshops Some are used for holding tools such as millingcutterssomeareusedforbarorworkpieceswhilesomemaybeusedwithbothbarandworkpiecesOne of the commonest is the ER collet which comes in

severaldifferent sizeseachhavingadifferent largediameterTheERcolletsystemallowsupto0039in(1mm)collapseofa

colletalthough in thesmaller sizesyoucanbuy thecollets in05mmincrementsA16mmcolletforexamplewillholdroundmaterialdownto15mmdiameterWhatevertheERcolletsizetheyallappear togodownto1mmminimumwhichwillclosedownto05mm

ERcolletadaptor

TherearemanytypesandsizesofERholderavailableAlltheusualMorse taper shank sizes are available and you can alsobuyvariousdiametersofextendedparallel shankholdersTheproblemwiththeseisthattheyaregreatforholdingtoolsthathave a short shank but because you need to use the holderwithadrawbaryoucanrsquotputlongbarstockrightthroughthemTo overcome this for lathe work you can also buy ER colletholdersdesignedtobefittedtoachuckbackplatethatyoucanmachine to suit your lathe so ensuring good concentricityBecause they donrsquot use a drawbar you can fit bar stock rightthroughandintotheheadstockmandrel

ERcolletadaptorfittedtoabackplateIalwaysleavebackplatesoversizesoIhavesomethingwithwhichtoclampthemdownwhenusedonamillordrill

When buying new and second-hand ER collets make surethey have the retaining groove near the nose end The older(andobsolete)EandEScollet typesdonothavetheretaininggrooveandarenotinter-changeableYouaremostlikelytofindEandEScolletsincludedwithasecond-handUnimatlatheDraw-in collets are usedwith a drawbar or collet tube The

drawbardrawsthecolletuptightbydrawingit intothelathersquosmandrelbyabar that runs through thecentreof themandreland screws into the centre of the collet Thismeans that youcannotputbarstockrightthroughthecolletToovercomethissome Morse taper collets use a hollow draw tube the collethaving an external thread tomatch the internal thread of thedrawtube

Draw-incollet

Special collets are made for the Myford ML7 Super 7 andML10 lathes These are Morse taper collets but rather thanhavingadrawbartheyareclosedwithanoseringthatfitsoveragrooveinthecolletThenoseringtightensthecolletintotheheadstockmandrelrsquos Morse taper It is extracted after use byundoing the nose piece which draws the collet out from theMorsetaperbythenosegrooveImperialandmetriccolletsareavailableuptofrac12in(12mm)diameterDead lengthcolletsareavailable that fit intoanattachment

usually fixed to the front of the lathersquosmandrel These colletsarecalleddeadlengthbecausetheydonotmovelongitudinallyunlike draw-in collets You are more likely to find collets likethesesecond-handratherthannew

BoxedsetofMyfordcollets

Deadlengthcollet

AvariationofthedeadlengthcolletistheCrawfordMultiborecolletThissystemhascolletsmadeofsegmentsheldtogetherbyspringsThecolletsareofvariablediameterandhavequitea

largeclosurerangeTheyaremorelikelytobefoundonalargercommercial lathe although you can get collets for smallermachinesWatchmakerrsquoscolletscanbeused inmost lathesbymaking

an adaptor for the headstock and a drawbar (or tube)Watchmakerrsquos collets are very accurate and can go down toverysmallsizesbuttheyhavelimiteduseinmostworkshopsYou can get a special watchmakerrsquos spindle for the EmcoUnimatlatheandthereisalsoaversionoftheCowellslathetheCW90thattakeswatchmakerrsquoscolletsFormost of thework carried out on the lathe youwill find

thatanERholder thatmountsontoachuckbackplate ismostuseful

Simpleexpandingmandrel

Simpleplainmandrel

MAKINGMANDRELS

There are several types of mandrel in common use inworkshops The most common is probably the expandingmandrelwhichcaneasilybemadeinanyworkshopInitsmostbasic form it is a bar turned to a size to fit the bore in theworkpieceItisthenthreadedwithataperedtapandslitat90degrees togive foursegmentswhichare thenexpandedbyascrewfittedintotheendofthemandrelAnother common mandrel is the tapered mandrel This is

usuallyalsquobetweencentresrsquomandrelandisoftenmadetotaperfromjustacoupleofthouovernominalsizetoacoupleofthouunder nominal size It is usually hardened and has a groundfinishTheworkpieceisheldinplacebybeingpushedontothemandreluntilitistightToremoveitjustpressitbackoutthewayitwentinWhereconcentricityisnotquitesoimportanttheworkpiece

canbeputonaplain turnedmandrelandtightenedupwithaboltandflatwasherExpandingmandrelsarealsomadecommerciallybutasyou

need a mandrel for each individual size of hole it can getexpensive if you need more than one or two different sizesCommercialmandrelscanbeobtainedwithMorsetapershanksto plug straight into the headstock Thismethod ensures thatthe mandrel should run dead true assuming both the Morsetapermandrel and theMorse taper in the headstock are bothcleanandfreefrommarksorswarfYou can also purchase Morse taper arbors with blank end

pieces from which to make your own mandrels First we willmake an expandingmandrel from a blank Morse taper arborYouwillneedtoturnthearbordowntofittheworkpieceboreIusually turn themandrelabout0010in (0025mm)oversize tostartwithandthenIdrillandtapthearborwithataperedtapThe drilled hole can go quite deep but the tapped hole onlyneedstogoinuntilthelockingbolt isabouthalfwaydownthelengthwheretheworkpiecewillsitPut the mandrel into the vice and cut along the mandrel

making four cuts around the circumferenceRetap thehole to

cleartheswarf fromthethreadandputthemandrelback intothe headstock taper Now you can lightly nip the screw up toexpandthemandrelslightlySkimthemandrel to finishedsizeuntil the workpiece will fit on without shake You can nowfurther tighten the screw so that the workpiece tightens ontothe mandrel When you slacken the screw the workpiece willcome off easily as you have skimmed it while it was slightlyexpandedYoucanmakeanexpandingmandrelfromabarheldin the three-or four-jawchuckorperhapsacollet inasimilarway Ifheld inachuck itmaynotgoback true ifyouneed touseitagainsoifpossibleyoushouldholdthearborinacolletFor aplainmandrel turn thediameter to fit theworkpiece

anddrillandtapforacapscreworaboltThereisnoneedtosplit this type ofmandrel You simply put the workpiece ontothemandrelandholditonwithaflatwasherAgainitdoesnotmatterwhetheryouuseabarinachuckorcolletorifyouusea Morse Taper blank arbor Arbors are very useful in theworkshop If youmake them fromMorse taper blanks or holdtheminacollettheycanbeusedoverandoveragain

8TaperTurningandLatheAccessories

Thischapterexplainshowyoucanturnataperusingatopslidetheuseoffixedandtravellingsteadiesandformtools

Turningataperwiththetopslide

TAPERTURNING

SometimesyouwillhavetoturnataperintheworkshopThatisa fairly easy jobWhat ismore difficult however is having toturnmatchingmaleandfemaletapers

Themethodyouaremostlikelytouseintheworkshopistoturn the two tapers with the top slide You should be able toturna taper longenough foraMorsetaperusingthismethodThemostimportantthingwhenturningtapersistoensurethatthe tool tip is at the exact centre height of the lathe This isbecause the taper will vary if the tool is not dead-on centreheightProbably the easiestmethod of turning aMorse taper is to

useadial test indicator toclocka lathecentreof therequiredMorse taper between centres The smaller end of the tapershouldbeatthetailstockendofthelatheThetopslideshouldbewoundalongthetaperby itshandwheelwhilethecarriageremainslockedThetopslideshouldbeadjustedangularlyuntilthedialtestindicatorreadszeroallthewayalongNowyoucanfinish turn the external Morse taper using an internal MorsetapersleeveasagaugetocheckthattheangleiscorrectTodothis make marks with a felt tipped pen along the taper andcheck that the test sleeve rubs evenly all the way along themaletaperAdjustifnecessaryuntilyouhaveaperfectfitToturnthematchingfemaletaperthelargeendofthetaper

willbeat the tailstockendand theboringbarwillbe invertedandcuttingon thebackof theholeDoing thismeans thataslongasbothofthetoolsareatcentreheightthetapersshouldmatchWecanusethemaletaperthathasjustbeenturnedasatestbarBoreoutthetaperverycarefullyyouwonrsquotneedtoremovemuchmaterial before the test taper goes too far intothe finishedbore Testwitha felt tippedpenuntil youhaveaperfectfitYou can turn any taper you need this way you are not

restrictedtoMorsetapersAnothermethodmostoftenusedforlongshallowtapersistouseataperturningattachmentTheseattachments are often available as extras on higher qualitylathes They comprise a slide mounted onto the back of thelathe Often the guide is dovetailed with a sliding blockattached to the cross slide to guide the tool on a taper ThedepthofcutisusuallyputonusingthetopslidesincethecrossslideisusuallydisconnectedfromthefeedscrewInthiswayit

isfreetomoveinandoutcontrolledbytheguide

Taperturningattachment

Settingthetopslidebyclockinganexistingtaper

Anothermethodweshalllookatfortaperturningistooffsetthe tailstock on its base This will make the work turnedbetween centres become tapered either large or small at thetailstockenddependingonwhichwaythe tailstock isoffset ifsettowardsthebackofthelathethediameterwillbelargerat

the tailstock end if the tailstock is moved to the front thetailstockendwill be smaller indiameter Theamountof taperthatcanbeturnedinthismannerislimitedsincetheheadstockandtailstockcentresareoutoflineThe final method of offsetting the workpiece is by using a

boringhead inthetailstockYouneedahome-madehardenedsolidcentrethatfitswheretheboringtoolwouldnormallygo(AsmallUnimatlathesizerunningcentremightbeideal)SettheboringheadsothetooltravelishorizontalYoucanthenoffsettheboringheadcentresocreatingataperThisisthesameassetting the tailstock over but you donrsquot have to realign thetailstockafterwards

Usingthefixedsteady

USINGFIXEDANDTRAVELLINGSTEADIES

The fixedsteady isusedmainly to turn theendofabaror tocentre a workpiece that is too large to fit through the chuckObviously bar stock should not protrude from the chuckmorethan is necessary to work on This is where the fixed steadycomesinThefixedsteadycanbesettothediameterofthebarsothattheendofthebarcanbemachinedsafely

Thesteadycanbesetusingachuckmountedonthistailstockadaptor

Travellingsteady

Settingthesteadybyusingachuckmountedonanadaptor

Onewaytosetthefixedsteadytosizeistoturnabitofbarin the chuck to the same size as the barwewant to use thesteadyonThenwecanmovethefixedsteadyalongthelathebedandfittheworkpieceintothechuckandinthesteadyTheendof thebar nearest to the tailstock shouldnowbe runningtrueandcanbeworkedonsafelyThebarcanbecentredrilledfacedorotherwiseworkedonAn alternative way to set the steady is to support the

tailstockendof thebarwitha threejawchuckmounted in thetailstockAdaptors to take the threejawchuckareavailableoryoucouldmakeyourownJustsupportthebaratbothendsinthethreejawchucksandsetthesteadyfingerstothebarThe fixed steadycanalsobeused to support tubes thatdo

nothaveanymaterialinthecentreThe fingers of the steady need to be lubricated regularly

while inuseThis iseasilydonebydrillinga smallhole in thetopfingerwithacountersinkinsidetheslottotakeoilThetravellingsteady ismostoftenusedwhenturningdown

small diameterbarsor screwcutting long slenderbars It boltsonto the front of the cross slide in line with the chuck and

travelsalongwhenthecrossslideismovedalongthelathebedWhen turning the travelling steady can either be set to thediameterofthebarbeforeturningandtoleadthetooloritcanbesettothefinisheddiameterrequiredandtofollowthetoolNormallythefingersaresetto leadtheturningtoolbut if thebarisroughforexampleifitisdentedorrustyitisbetterforthefingerstotrailtheturningtoolIfscrewcuttingthetravellingsteadyshould lead the toolso that itdoesnotdeflectorwearduetoaburrbeingthrownupbythescrewcuttingtoolSteadies will not be used very often but they are

indispensableontheoccasionswhentheyareneeded

Travellingsteadywithleadingfingers

Travellingsteadywithtrailingfingers

MAKINGASIMPLEFORMTOOL

Youmay often need to produce a particular shape such as aradiusonacomponentTheeasiestmethodtodothisiswithaformtoolAsanexamplewewillmakeasimpleformtooltocutahalfcircleonabarofbrassForaradiusof3mmforexampleweneedtoproducea formtoolusinga6mmdiameterdrillorreamFormaterialwewillusegaugeplateahighcarbonsteelthatcomesintheformofagroundflatbarApieceabout5mmthick and10mmwide is needed although the size is not thatimportantaslongasthegaugeplateisthickenoughtoabsorbanyturningstressesIdeallyweneedataperedreamerthatwillproduce a 6mm diameter hole somewhere along its lengthalthough you could use a parallel 6mm reamer a slot drill orendmillorevenastandardtwistdrillDrill a hole through the gauge plate and open up to 6mm

diameterAim togetagoodsurface finishon thesidesof thehole Hacksaw and file half the hole away to leave the shaperequired on the finish turned component Now we need to

harden the tool although ifweare justdoingacomponentortwoinbrasswecouldprobablygetawaywithouthardeningitHardeningissimpleenoughheattheworkingendofthetool

toredstopheatingandletthegaugeplaterestforacoupleofminutesThiswillgive thegaugeplateachance tochange itsinternalstructureReheattoredandquenchinatubofwaterThisshouldhardenthetoolAlthoughabitbrittle itshouldbefine for making a few components Stone the top of the tooluntil thecuttingedge issharp Ifnecessaryyoucanpolishtheinside of the radius that is going to do the cutting There areseveralmethodsyoucanuse includingapieceofwetanddrypaperaroundabitofbaraverysmallgrindingwheelcalledamounted point or a bit of round bar with fine valve grindingcompoundonitWhicheveryouuseaimforapolishedfinishasthe finish on the turned component is directly related to thefinish on the form tool You canmakeall sorts of simple formtools with gauge plate a typical example being a facing toolwitha30-degreechamfertofaceandchamfernuts

CopytemplatereadytouseMetal

MachiningfromaTemplate

MachiningfromaTemplate

YoucanmachineaprofilefromasimpletemplateThetemplatecanbecutfromgaugeplatewithafileormachinedbutitdoesnot need to be hardened The template could be used tomachinea large radius suchasa smokeboxdoor Inuse thetemplateismountedonablockonthelathebedandthecrossslide is kept in contact with the template by being pushedagainstthetemplatewithaballracefixedtothecrossslideInthenextchapterwewillbelookingatdrillingandreaming

9DrillingandReaming

ThischapterexplainshowtousedrillsandreamersinthelatheTherearemanydifferenttypesofdrillsandreamersTheyareessentialtomakingcomponentsinthelatheWewilllookatthevarioustypesandhowtochoosethespeedsandfeedsforusingthem

Thisdrillchuckrequiresachuckkey

TYPESOFDRILL

Drills are normally held either in the tailstock if they have aMorsetaperor inadrillchuckiftheyhaveaparallelshankA

drillchuckismountedonaMorsetapershankthatisusuallythelargestMorsetaperthatthetailstockwilltakeThelargestsizeof drill that will normally fit a drill chuck is frac12in (13mm) indiameter although larger chucks are available at a cost Thesmallest sizeofdrill thatafrac12in (13mm)drill chuckwill take isusually about 116in (15mm) This is because the larger drillchuck is incapableofclosingdownenoughto take thesmallersizesofdrillThismeanswewillprobablyneedtwodrillchucksoneforlargerdrillsandoneforsmallerdrills

Hand-tighteningdrillchuck

TherearetwomaintypesofdrillchuckOneistightenedbyusinga chuckkeywhichhasa small bevelgearbuilt on to itthatmates with the outer sleeve of the drill chuck itself Theother type is hand tightenedwhere the outer chuck sleeve isknurledtotightenthedrillthesleeveisturnedbyhandLargerdrillsabovefrac12in(13mm)usuallyhaveaNo1orNo2

MorsetapershankYoucangetMorsetapersleevestoconvertalargeMorsetoasmallerMorsetaperYoucanalsogetasmallMorsetolargeMorsetaperconverteraswell

Drillwithataperedshank

Some larger drills are also available with parallel shanksTheyaremadewithasteppeddownfrac12inparallelshankandarecalledblacksmithrsquosdrills

Blacksmithrsquosdrill

Themostusefuldrills in theworkshopcomeassetsofhighspeedsteeljobberdrillsinacaseThemostpopularsetcovers1mmto6mm increasingby01mmstepsAnotheruseful setcoversfrom6mmto10mmalsoincreasingby01mmstepsIfyouareintomodelengineeringasetofnumberdrillsfromNo1toNo60istoberecommended

Asetofmetricdrillscovering1ndash6mm

Drills are also available in different lengths Stub drills areshorter than standard jobber drills Several lengths of longseries drills are also available ranging from one and a halftimesthelengthofajobberdrilluptoseveraltimesthelength

Differentlengthsofdrills

Mostdrillshavetwoflutesbutcoredrillsarealsotobehadwith three four or evenmore flutes As their name suggeststhese are usually used for drilling out cored holes in castings

CoredrillsarenotnormallycapableofstartinganewholebutareusedforopeningupexistingholesAstandarddrillusuallyhasanincludedangleof118degrees

Stub drills and cobalt drills often have a 135 to 140 degreeangle for use on hardermaterials such as stainless steel andaircraftsteelsBack rakeondrills is oftenground radially Another typeof

pointhoweverhasfourfacetstothepointFour-facetdrillsaremuch better at starting a hole than a standard jobber drillwhich tends towanderunless followingacentrepoporcentredrill Four-facet drills also require less pressure to drill a holesincethepointisthinnerthanastandarddrillandtheyarefareasier to sharpen accurately by hand than standard jobberdrillsDormerdoarangeoffour-facetdrillscalledA002withatitaniumnitridecoating(TiN)andafour-facetpoint

Three-flutecoredrill

DormerA002four-facetdrillpoint

To drill an accurate sized hole requires two ormore stepsfirst youdrill the hole undersize (by perhapsfrac12mm) then youfollowthroughwithasizedrillThechancesaretheseconddrillwillcutdeadtosizeasitisonlycuttingasmallamountfromthediameter Obviously if you are drilling a large hole moreintermediatestepsmayberequiredSpeedsfordrillingarethesameasthosegivenforturninginthetableinChapter3

Setofcentredrills

REAMERS

There are several types of reamers available for use inworkshops again with either Morse taper or parallel shanksSomehavesizeparallelshankstheshankbeingthesamesizeas the reamer while others are availablewith shanks smallerthanthereamedsizeThereisalsothewaistedreamerwheretheshankisthesamesizeasthereamerthemiddleissmaller(waisted)andthecuttingendistheholesizeYoucanalsogetadjustablereamerswheretheendisexpandedbytheuseofascrewinthecuttingendofthereamer

Handreamerthefrontparthasaslighttaper

Straightshankmachinereamer

Waistedshankmachinereamer

Morsetapershankmachinereamer

Parallelreamersaredividedintotwotypesparallelmachinereamerswhere thecuttingdiameter is thesameallalong theream and hand reamers where the cutting end is slightlysmallerandtapersuptothefulldiameterWhen drilling a hole for reaming it is advisable to use the

two-holemethodfordrillingYouaremore likelytogetagoodsize hole prior to reaming For small reamers up to 04in(10mm) leave about 0012in (03mm) for the reamer toremoveForreamersuptofrac34in(19mm)leave0016in(04mm)and over frac12in (13mm) leave 0020in (05mm) For reamingspeedsuseabouta third toahalfof thedrillingspeed for thesamediameterFeedsshouldbefrom0002to0004in(0025ndash005mm)per toothper revMultiply the feedper toothby thenumberofteethtogivethefeedperrevolutionItisbesttouseneatcuttingoilformostmaterialsexceptfor

aluminiumforwhichparaffinshouldbeusedandplasticwhichrequirescompressedairorplainwaterYoushouldnotuseoilasacuttinglubricantforanytypeofplasticasitcanattackandordegradetheplastic

10BoringToolsandBoringHeads

Thischaptershowsyouhowtoboreholesinthelathewiththeworkheldinachuckmountedonthefaceplateorfixedtothelathecrossslide

TypicalHSSboringbar

DIFFERENTTYPESOFBORINGBARS

BoringaholetosizeisoneofthemostexactingjobsyoucandoinalatheItisrelativelyeasytoturnashafttofitaholebutitis much harder to bore an accurate hole to fit a shaft Ifpossibleyoushouldboretheholebeforeturningtheshaft

YouarelikelytocomeacrossHSSboringbarsorinsertedtipboringbarsBothhavetheirusesTheHSStoolisidealformostgeneralhole-boringjobsbuttheinsertedtiptoolisfarsuperiorfor materials such as cast iron The boring bar should be aslargeasyoucangetintotheholewhilestillallowingswarftoberemovedTheboringbarshouldonlyprotrudefarenoughtoenableitto

go completely through the bore Any more protrusion than isnecessarymay result in chatter or a dig in in the bore Thefront clearance on the boring bar tip should be as small aspossiblewithoutrubbingasstrengthisimportantBoringcanbeusedtofinishaholetosizeorsimplytotruea

holeupafterdrillingandpriortoreaming It isbesttoruntheboringtoolthroughtheholeusingafinefeedtothecarriageifyouhave the feedoptiononyour latheThe final finishingcutshouldbeputthroughtwoorthreetimesatthesamesettingtoeliminateanyspringinthetoolworkorlatheIftheholehasanintermittentcutthroughitsuchasacrossholetheholeisbestboredtosizeIt ispossible toborequite smallholes if youhave the right

tool Commercial lsquosmall holersquo boring tools are very expensivebut Ibuythemsecond-handwhenever Iseethemso Iusuallyhave a stock It is easy if time consuming to grind up smallboringbarsbuttheyareveryusefulespeciallywhenyouneedtotrueupasmallholepriortotappingorreamingEndmillsandslotdrillsmakeusefulboringtoolsAs longas

yougetthecuttingedgeoncentreheighttheywillboreaswellasaproperboringbarespeciallyinaluminiumYoucanmakesimplehome-madeboringtoolsbydrillingand

reamingaholetotakeaHSStoolbitintoasteelshankIdeallythe shank should be made of high tensile material or silversteelThetoolbitshouldbesecuredwithahightensilesocket-headedgrub screwor similar The tool bit caneitherprotrudefromthesideoftheboringbarforthroughholesorprotrudeatthe frontof theshankat45degrees ifyouareboringablindholeRoundboringbarscaneitherbeclampedintotheVeegroove

foundinsometoolholdersorheldinasplitsquareshankEithermethodissuitableespeciallyastheshankcanbeslidinoroutofthetoolholdertominimizeprotrusionSpeciallyshapedtoolbitscanbeusedtoundercuttheendof

the borewhen it needs to be screwcut and canrsquot be cut rightthrough Inserted HSS boring bars can also be ground up forundercuttingbeforescrewcuttingThereareseveralmethodsofcheckingaboreforaccuracyIf

youhavetoboretheholetofitanexistingcomponentperhapsaballraceyoucanuse theexistingcomponentasagaugeorturnupagaugeRoughout theborewithina few thouof thefinishedsize taking twoor threespringcutsUsea telescopicgaugeapairofcalliperswithamicrometeroradigitalverniertomeasuretheholeBorethestartoftheholebynomorethanonethouata timedonotgoright throughtheboreTest thefrontoftheboreifthegaugedoesnotgointotheborerunthetool right throughunderpower feedBoreout the frontof theholebyanotherthouchecktheboreandrepeatuntilthegaugejustgoesintothestartoftheholeFinishtheboreatthesamesetting checking that the gauge just enters Take a couple ofspringcutstoensuretheboreisparallelYoushouldnowhaveanaccuratelysizedholeThe trick to boring is to finish with very fine cuts Many

engineersdonotrecommendfinecutsbutIhaveneverhadaproblemaslongasthetoolissharp

Asetoftelescopicgaugesforcheckingaboreusedinconjunctionwithamicrometer

Checkingaborewithahome-madegaugeTheleadinisonethousmallerthantheborerequired

USINGABORINGHEADINTHELATHE

AnothermethodofboringacomponentinthelatheistoboltitdowntothecrossslideWhentheworkpieceisbolteddownandtheholeposition is linedupwith theheadstock youcanboretheholeintheworkpieceinseveralwaysFirst however you might need to put a hole into the

workpiece to clear the centre of the hole out of theway Youcandothisbyusingadrillinathree-orfour-jawchuck(smallerdrillscouldbeusedinadrillchuck)Startwithasmalldrillandworkupalmosttothefinishedsizeoftheholetobebored

Boringaholereadyforreaming

Toboretheholethefirstoptionistoholdaboringbarinthethree-jaw chuck This is a good basic method of boring aworkpieceonthecrossslideTheonlyawkwardbitisadjustingtheboringbarsothatasizeholeisboredThisisusuallydonebyanadjustingscrewpressingontothebackofthetipoppositethe cutting edge The tip itself is usually clamped by a grubscrewthroughthesideoftheboringbarHoweveryoucanuseaboringbarthatisafewthouundertherequiredsizeandfinishoffwithareamerA similar way that is easier to adjust is to use the same

boringbar in the independent four-jawchuckThen insteadofadjusting the tip in the boring bar you can adjust the entireboringbar inthefour-jawchuckThisasyoucanimaginewillbealoteasierthantryingtoadjustthetipintheboringbarThethirdmethodofboringworkonthecrossslideistousea

properboringheadThis iseasy toadjustas it isdesigned forthisverypurposeFinallyyoucouldusea lsquobetweencentresrsquoboringbarwhich

isheldbetweentheheadstockandtailstockcentresThisistheonly option when you are doing a long bore such as a largecylindercastingforalocomotiveortractionengine

Boringtheholeusingthefour-jawchuckmethod

Usingtheboringheadinthelathemandrel

Unlike when you are facing and boring a component in achuck you will not be able to face across the front of thecomponent (Boring heads with the ability to face across theworkareavailablebutareunlikelytobefoundintheamateurrsquosworkshop) Thismeans you will have to face across the workwith a flycutter in order to keep the face true with the boreFlycutters are available quite cheaply or you couldmake yourownandholditinthefour-jawchuck

Aflycuttersuitableforfacingthefrontofacomponentthathaspreviouslybeenboredonthe

crossslide

11KnurlingRadiusTurningandProductionMethods

This chapter explains how to use knurling tools and radiusturningtoolsaswellasusingbasicproductionmethods

KNURLING

Knurlingistheprocessofformingorimpressingapatternonapiece of metal often for the purpose of making a grip for apieceofequipmentsuchasaknobBothstraightanddiamondknurlscanbeproduceddependingonthetypeofknurlyouareusing Diamond knurling is usually done with two knurlingwheelsalthoughsingle-wheeldiamondknurlsareavailableKnurls are also available in fine medium and coarse sizes

although the size is relative fromdifferentmakers The speedfor knurling is usually about half of the turning speed for thesame diameter bar Normal knurling is of the male patternwheretheknurlingconsistsofraisedpyramidsFemaleknurlingismuchrarerandconsistsofdepressedpyramidsThere are threemain types of knurling tool but only two of

these are found in the average workshop The first type ofknurling tool is the so-called lsquocutrsquo knurling toolwhichactuallycutsaknurlratherthanpressestheknurlintotheworkThisisaspecialized tool more often used in industry and is veryexpensivesoitisnotfoundinmanyhomeworkshops

lsquoBumprsquoKnurling

The most common knurl is the single-or double-wheel knurlsometimes called a lsquobumprsquo knurling tool The wheels aremountedat the frontof the tool This typeof knurl is pressedintotheworkbyusingthecrossslideandcanproduceagoodqualityknurlHowever itdoesputveryheavypressureonthemandrelandlathebearings

Acommerciallyavailablestraddleknurlingtool

StraddleKnurling

Thebest typeofknurl foroccasionaluse is thestraddleknurlwhich has two knurling wheels that completely straddle theworkpieceThistypeofknurldoesnotputastrainonthelathebearings and so is preferred bymost lathe users (Two-wheelknurlingtoolsareavailablethatresemblestraddleknurlingtoolsbut they donrsquot open up to take anything more than smalldiameters relying on pressure at the side of the job like alsquobumprsquoknurl)To set the straddle knurl up wind the tool against a bit of

plateheldontothesideofthebarRemovetheplateandmovethetoolinbythethicknessoftheplatehalftheknurldiameterandhalfthebardiameterThiswillputthetoolontothecentrelineofthebar

Settingtheknurlingtool

In use set the knurling wheels to the centre as describedabove wind the knurls onto the outside diameter of the barwindtheknurlawayfromthebarandmovetheknurlingwheelsclosertogetherbytwicethedepthoftheknurlpatternSwitchthelatheonandwindthetoolbackontothecentrelineandthetool should start to form the knurl You can now traverse theknurlingtoolalongtheworkpieceto formtheknurl remembertousecuttingoilNote that theknurlsshouldhavechamferedsidesifyouaretraversingalongtheworkpieceYouneedtogodeepenoughsotheknurlisfullyformedbut

notsodeepastodeformtheknurlBecausetheknurlstraddlestheworktheknurlsstartoff independentlyandmaynotbe inalignment around the diameter Once you start moving theknurlingtoolbackwardsandforwardsalongtheworkhoweverthetoolshouldlineitselfupThismeansyoumayhavetoturndownorpartoffthebarwhereyoustartedtheknurlIfyougotoodeepespeciallyinaluminiumthewholedepth

ofknurlcouldgetdestroyedandevendropoff theparentbarThis is called flakingKnurling isnotadifficultprocessa littlepracticewillsoonhaveyouknurlinglikeaprofessionalengineer

Anaccomplishedbitofknurling

AformtoolcuttingaballTheinsetviewshowstheformtoolandafinishedball

RADIUSTURNING

Sometimesweneedtoformanexternalradiusontheendofabit of bar perhaps for a ball-shaped handle We can use asimple lathe attachment to do this Basically the attachment

consists of a short turning tool mounted onto a U-shapedcomponent that is arranged to pivot on another U-shapedcomponentheldinthelathetoolpostBy pivoting the attachment back and forth a radiuswill be

generatedForatrueradiusthepivotpointshouldbesetonthecentrelineofthebarTheradiusgeneratedwilldependonhowfarthetoolbitissetbackfromthecentrelineoftheworkpieceTosetthetoolupwindtheattachmentuptoaplateheldto

the sideof thebar youareworkingon remove theplate andwindinthewidthoftheplatehalfthewidthofthebarandthewidthofthefixturetothecentrelineofthepinThiswillputthepivotonthecentrelineThenyoucansetthetooltotheoutsidediameterofthebarThiswillproduceaballthesamediameterasthebarTo turnan internaldiameteruse the samemethodbut the

turning tool will need to pass through the centre of the pivotand out the other side You will be limited to shallowdepressionsratherthanlargesemicirclesbutthistechniquecanstillbeusefulonoccasionThealternativemethodof formingaball iswithaball form

tool

Astopbarblockforthecarriagestop

PRODUCTIONMETHODS

PRODUCTIONMETHODS

Foreaseofproductionthefirstthingyouneedtouseisabedstop (see Chapter 5) The chances are that you will need tomakeyourownTheoneIuseisveryversatileandconsistsofablockmountedatthefrontofthelatheheadstocktogetherwitharodtoactasthestopDependinguponwhatyouaredoingitmaybeusefultohave

morethanonestopbareachwithitsownseparatestopblockInusethebarisinsertedintothemainblockasfarasthestopblock(if fitted)andlockedinplaceThefirststopbarcouldbeusedto facetheworkpieceandthesecond(shorterbar)couldbe used to turn along the diameter while a third bar couldpositionthepartingofftoolAnalternativeadditiontothestopbarcouldbeawasher(orwashers)ofknownthicknessplacingthewasher(orwashers)onthebarwillextendthestoppositionbythethicknessofthewashersusedAusefultipistostampanumberonthestopblockssothat

eachone isnumberedYoucouldalso stamp the thicknessonthewasherssoyoudonrsquothavetokeepmeasuringthemandjustpickthemupinthecorrectorderItsavesalittletimeandhelpsavoiderrorsThe whole point about using a stop is the consistency of

positionwhichistransferredtotheaccuracyofthecomponentit gives Once you have learnt to use a stop youwill wonderhowyoumanagedwithoutitEvenforone-offcomponentsitwillsaveyoutimeForatypicalone-offsteppedshaftsetthestopsotheturning

tooljustfacesthebarandfaceoffMove the top slide along for the length of the turned step

requiredTurnthestepYounowhaveastepontheendofthebarofaknownlengthNofiddlingnomeasuringndashyouknowitiscorrectUsing the bed stop offers a simple way of doing repeat

turning of lengths and diameters in the lathe Stops are notlimited to production methods they are very useful formachiningone-offsaswell

A single stop bar will serve for much of the work you aredoingbutsometimesyouneedmorethanonestopTheanswerhereistousemorethanonestopbarinconjunctionwithastopblockEachbarhasitsownstopblockthatcanbetightenedupThenyoucaninterchangethestopbarsandeachbarcanbesettotherequiredlengthbyusingavernierorruleYoujustsetthetwostopblockstothedifferencerequiredandlockthestopbarintheholderasnormalWhenyouneedmorethanoneofeachitemitisveryeasyto

save time in theworkshop once the lathe is set up you canmake several items in quick succession A typical example ofthis type of production is a simple spacer Set a facing andchamferingtoolinonetoolholderapartingofftoolinanothertoolholderandadrillinthetailstockchuckThefacingtoolandparting off tool are in fixed positions to each other so it is asimplematter of drilling thehole facingoffwithone tool andparting off with the other As long as the gap between thepartingofftoolandthefacingtoolremainsconstantthespacerswill remain at the samewidth each time youmachine one ofthemTheeasywaytosetthethicknessofthewasheristofaceoff

theendofthebarbringthepartingofftooluptothefinishedface and lock the cross slide Wind the parting off tool backslightly so you can move the bar forward in the chuckMeasuring with the vernier calliperrsquos depth rod from therighthandfaceofthepartingofftoolbringthebaroutslightlylonger than is needed for the washer thickness Using thetailstock chuck drill the hole using a centre drill for the firstwashertoensurethedrill runstrueNowsetthefacingtool inpositionfaceoffthewasherandpartofffromthebarMeasurethe washer and adjust the facing tool either way so that thethicknessof thewasher iscorrectPull thebar fromthechuckslightlyfurtherthanthefacingtoolsothateachwashercanbefaced to lengthYoucanmakeasmanywashersasyouneedall of the same thickness The same applies to nuts and anyothercomponentthatneedstobeasetlengthIfmakingboltsor screws theprinciple is thesamebutyou

willneed to turndown thediameter tobe threadedThis timethedifferencebetweenthepartingofftoolandtheturningtoolisthethicknessoftheheadInordertofacetolengthhoweverawasher of a known sizemust be inserted between the stopblockandthecrossslideThiswasherwillbethelengthoftheturneddownportionofthecomponentIfyouwanttomakeabatchofcomponentsbutdonrsquotwantto

keepmovingorchangingtoolsyoucanmachinethebatchonestepata timedoingoneoperationoneachcomponentbeforedoing the next operation on all the components Repeat thisuntil the complete batch ends up as completed componentsYou have the added advantage that the components willprobablyallbethesameshapeandsizesomethingthatisnotalwayspossiblewhenmachiningeachcomponentindividuallyTo make a batch of components such as washers to the

samethicknessisquitesimpleSetupapartingtooltopartoffthe components and set up a facing tool to face thecomponentsThedifferenceinpositionbetweenthefacingtooland the parting toolwill be the thickness of thewashers Youcanadjustthethicknessofthewasherbymovingthefacingtoolbackwardsor forwardswith the topslide toadjust it The rearpartingofftooldoesnotmoveotherthantopartoffthewasher

Makingwasherstothesamelengthusingfixedpositiontools

TAILSTOCKTURRET

AnotherusefulaccessoryisthetailstockturretThisisarotatingheadthatisusuallysetbackatanangleItfitsintothetailstockof the lathe and has multiple stations to take different toolsoftenitwilltakefourfiveorsixtoolsThebenefitofthisisthatitcanhaveabarendstopacentredrilladrillacountersinkatapandadieoranycombinationthereofallsetupreadytousein sequence The tools normally fit into holes bored into theturretToavoidtoolsstickingouttoofar it isbesttousestubdrillsinsertedintoroundbarsthatfitintotheturret

Anindexingturretthatfitsdirectlyintothetailstockofthelathe

YoucaneitherdrillandtaptheroundbarsoruseLoctite tosecure the drill in the round bar You can also buy roundadaptorswithaJacobschucktapermachinedontheendtotakechucksAnothermethodoffittingchucksistodrillandtaptheround bar to take chucks with threaded extensions ThesechuckscanoftenberetrievedfrombrokenBlackampDeckertypedrillsDieholderscanslideonapieceofroundrodintheturretFor

smaller diameter threads you can stop the die from rotatingusing your hand There is no need to reverse the lathe whenthreading just stop it and spin the die off by hand the samegoes for taps For larger taps and dies you can use a shorttommybartostoprotationbutmakesurethatthetommybarpositionisclosertotheworkthantheendofanyofthedrillsorthetommybarwillsnapthedrillsifyouletgoofitorifthetapordiejamsupYoucanalsomakeorbuyarunningcentretofitintotheturrettosaveremovingitwhenyouneedtousealathecentreOnlydothiswithsmallorlightworknotheavybarsorfor largecutsWhenused inconjunctionwithagoodbedstop

system a tailstock turret becomes a very versatile productionfacilityTheturretcanbemademoreversatilebyfittingalever-feed

tailstockattachmentoracapstan-style feedattachmenttothetailstockturretEitheroftheseattachmentswillmaketheturretveryfastinoperation

Anindexingturretsetupwithastopandacentredrill

Standardlever-feedtailstock

SECONDOPERATIONWORK

SECONDOPERATIONWORK

Sometimes it is necessary to do second operation work on apart-machinedcomponentUsually thiswillbeon theoppositeend to the one already turned There are two main ways ofholding theworkpiece in the correct position for furtherworkthechuckbackstopandsoftchuckjawsThechuckbackstopisquitesimpletomakeItconsistsofa

draw-incolletapieceofplainbarforthestopabitofthreadedbar a nut and a top hat collar The collet goes into the lathemandrelandisdrawninbythethreadedbarThethreadedbargoesthroughthemandrelandislockedinplacebythenutandthe tophatcollarat the left-handendThe tophatcollar is toprotecttheendofthemandrelThestopbarfitsthecolletandispositionedsothattheworkislocatedattherightdepthinthechuckThismeansthateachcomponentput intothechuckupagainstthebackstopwillalwaysbeheldinthesameposition

Capstan-stylelever-feedtailstock

Adraw-inbackstop

Softjawswithhexagonsadded

The secondmethod is to hold the component in soft jawswhich are bored out to hold the component (see Chapter 5)ThismeansthecomponentshouldrundeadtrueandeachonewillbeheldinthesamepositionreadytobemachinedSoft jaws tend to be used for larger components while the

backstop ismore likely tobeused forbarworkYoucanboltextension pieces to soft jaws to hold larger diameters orextensions can be machined to make a nest to take largercomponentsWhensoft jawsarewornoutandfaceddowntoo

lowforfurtheruseyoucanboltapieceofhexagonbartoeachjawtogivethemanewleaseoflifeIfyouhaveabatchofthreadedcomponentstofinishonthe

second end you can screw them into a bit of bar held in thechuck If theyarehexagonbolts just tightenup lightlywithaspanneriftheyareroundheadandtheheadwillbemachinedlateryoucouldtightenanduntightenthemwithapairofpliersThe more production work you do the more varied the

methods you will learn and the quicker you will makecomponentstoahighstandardofaccuracyA sensitive drilling attachment can be very useful when

drillingwith tiny drills The feed is by hand which gives it itssensitivity The attachment can also be used for small tapswherethetravelisfairlyshort

Machiningscrewheadsbyholdingthescrewinathreadedmandrel

Asensitivedrillingattachmentthatfitsintothe

tailstockchuck

ThisVeeattachmentisusedforcrossdrillingandcanbeusedintheheadstockorthetailstockofthelathedependingonthelengthofthebartobecrossdrilled

ThisisarevolvingtaperforthetailstockIfyoufitadrillchucktoityoucanuseitasarunningsupportforsmallbarwhereacentreisnotpermissible

12TapsDiesandScrewcutting

Thischaptershowshowtousetapsanddiestocutinternalandexternal threads in the lathe Italsoexplainshowyoucansetupasimplegeartrainandcutascrewthreadwiththehelpofascrewcuttingdialindicator

Atypicaldie

CUTTINGTHREADS

Threadcuttingeither internalorexternal isan importantpartoflearningtousealatheThepurposeofathreadisusuallysothatyouareabletoholdpartstogetheralthoughotherusesforthreadssuchasleadscrewsandfeedscrewsformachinetoolsareoftencalledfor

Safetyhasalreadybeencoveredindepth(seeChapter2)butafewextrawordsonsafetywhenthreadcuttingarecalledforWhen tapping a hole or threading a bar from the tailstock atailstocktapordieholderisoftenusedForthesmallerthreadstheholdershaveaknurledbodyandrotationcanbestoppedbysimplyholdingthebodyoftheholderinyourhandAslongasyoukeepyourhandawayfromthechuckandany

sharp lathe tools on the cross slide you should be fine (ifpossible remove either the tool holder or the tool itself )Providedthereisnothingtocatchorsquashyourhandonyoucan hold the knurled tap or die holder in your handwhile thelathe is running slowly under power and releasing the holderwhen the full length of the thread is cut or the pressurebecomes too great for you to stop the rotation (By slowly Imeaninveryslowbackgear)For largerthreadshoweveratommybarwilloftenneedto

beusedtostopthetapordieholderfromrotatingWhenusingthe tommy bar to prevent rotation do not under anycircumstances use the lathe under power Instead switch themachinerightoffandunplugit ifpossibleTurnthetapordieholdingthetommybarwiththerighthandandstopthechuckfromrotatingwiththelefthandThere are already many published charts providing thread

data covering such factors as tapping hole sizes minimummaximum and effective diameters as well as pitches andthreadsperinchIwillnotbeprovidingthemherebutwishtopoint out that tapping size drills can vary with the materialbeingcutWhenIamtappingsmallsizes instainlesssteel forexampleIusuallydrillthehole0004in(01mm)largerthanthefigurestated in thechartThisway Iam less likely tobreakatapinthehole

HSSorCarbonSteel

TapsanddiesareusuallymadefromcarbonsteelorHSSHSStapsanddiestendtoremainsharpformuchlongerthancarbonsteeltapsbutcarbonsteelisusuallycheaperNewcarbonsteel

tapsanddieswillprobablybefineforsmallerholesandsoftermaterials but wherever possible HSS should be your firstchoice Second-hand taps and dies are sometimes availablefromtoolshopsoroneBaybutinmyexperiencetheyareoftenbluntandnotworthbotheringwith

Lubricants

Whether tapping threading with a die or screwcutting it isnormallyessentialtousealubricantevenonbrassForbrassaluminium and bronze kerosene (paraffin) or white spirit isgenerallyusedandcanwithadvantagehaveasmallamountofcuttingoiladdedFor steel and stainless steel amodernpaste-based tapping

compound or cutting oil should be used This can also beappliedtocopperthismetalcanbestickybuttakeiteasyandall should gowell I also use paste or cutting oil on cast ironAlthoughmostrecommendationsaretocutcastirondryIhavefoundalubricanttobeveryhelpful

Screwthreadpitchgauge

ThreadGauges

When following a published design you will probably use thethread sizes as recommended by the designer If you are

making a thread to match an existing thread however youneedtofigureoutwhattheexistingthreadisThisiseasiesttodoonanexternalthreadIfyouhaveonlythenuttrytofindaboltthatwillfititandusethattocheckthethreadIfyoucanrsquotfindamatchingboltandtheholeinthenutisbigenoughyoucouldtrypressingabitofplasticineintotheinternalthreadandmeasuringthatTomeasuretheexternalthreadweneedtodeterminethree

thingsusingathreadpitchgauge theoutsidediameterof thethread the pitch of the thread and the thread angle Thesethree checks will probably be sufficient to decide what thethreadactuallyisBritish threads such as British Standard Fine and British

Standard Whitworth and also the Model Engineer threadsystemhaveanangleof55degreesAmerican threads such as UNF (Unified Fine) UNC (Unified

Coarse) UNEF (Unified Extra Fine) ANF (American NationalFine)ANC(AmericanNationalCoarse)are60degreesasisISOmetricUnusually theBritishStandardCycle thread is also60degreesThe other thread youmight come across is the BA (British

Association)threadThishasathreadangleof47frac12degreesandismetricbasedThelargestBAthreadis0BAwhichhasa6mmdiameterwith a 1mmpitch TheBA series godown to 22BAbutinpracticeyouareunlikelytocomeacrossanythingsmallerthanabout14BA

TAPS

TappingistheprocessofcuttinganinternalthreadwithatapFirst a hole is centre drilled and drilled in the workpiece Irecommend that you give the top of the hole a 90-degreecountersinktogivealead-intothetapandalsotostopthetapfromthrowingupaburrontothefaceofthework

Setofhandtaps

TypesofTap

The many types of tap can be divided into hand taps andmachinetapsHandtapsarenormallyheldinatapwrenchbutcan be held in the lathersquos tailstock chuck or a purpose-madetailstocktapholder

Close-upofahandsecondtap

WhentappingbyhandstartthetapuntilitstartstobiteandgiveitanextraturnorsoReversethedirectionofthetapforaturn to break the chip Continue forward for a couple of turnsand then reverseasbeforeContinue todepthor through theworkpiece by continually tapping a couple of turns reversingandcontinuingforwardThisshouldclearthechipsandpreventthetapfrombreakingIfthetapgetshardtoturntakeitrightoutoftheholetoclearanyswarfaddsomemorelubricantandcontinuetappingA set of hand taps will normally comprise a taper tap a

secondtapandaplugtapUsuallyyouwillstartaholewithataper tap This is a tap where the outside of the thread isreducedtowardsthepointbygrindingitonataperThistypeoftap can be used to start the hole but if the hole goes rightthrough the work it may be possible to screw the tap rightthroughtheholesoformingafullthreadrightthroughIfthetapertapistooshortorifyouaretappingablindhole

youneedtofollowthetapertapwiththesecondtapwhichhasmuch lessofa taper In fact itonlytapersrightat thestartofthetapTheplugtapisfinallyusedusuallytofinishoffablindhole

Theplugtaphasnotaperonitjustashortlead-inontheendBetween the three you should be able to tap themajority ofholesintheworkshopWhentappingblindholesitisbesttoworkoutthedepthand

fromtherethenumberofturnsneededforthetaptoreachthebottomoftheholeAsanexamplesaytheholeis9mmdeeptothepointThe tapenters2mminto theholebeforestarting tocutSo9mmless2mmgives7mmThepitchofthetapis05mm7mmdividedby05equals14sothenumberofturnstothebottomoftheholeis14Inpractice12or13turnswillbethemaximumneededWhen tapping blind holes make sure that all swarf is

removedfromthebottomoftheholebeforestartingtotap

Selectionoftapholders

HoldingTaps

TherearetwomaintypesoftapwrenchthehandtapwrenchwhichisdesignedtobeheldwithbothhandsandtheTeetypetapwrenchwhichoncestartedcanoftenbeusedone-handedTapsusuallyhaveeitheracentreholedrilledintheshankor

theshankisgroundtoapointThismeanswecansupportthetapfromthetailstockeitherbyusingalathecentreorbyabitofbarinthetailstockchuckwithafemalecentreinitTeetypetapwrenchesoftenhaveafemalecentreintheendandcanbesupported on a running centreWhen the tap is supported bythe tailstock at one end and the hole in theworkpiece at the

otheritmustbeinlinewiththeholeintheworkpiece

Machinetap

MachineTaps

Themaintwotypesofmachinetaparethespiralpointandthespiral flute The spiral point pushes swarf downwards throughthe hole while the spiral flute pulls the swarf out of the holeSpiralflutetapsaremuchweakerthanspiralpointtapsandintheory should not be used for tapping by hand However inpractice you can often get away with hand tapping using aspiralpointtapifyouareverycarefulIneithercasethetapisdesigned for continuous rotation swarf being automaticallycleared so the regular reversal as with a hand tap is notnecessaryIf you are careful you can probably get away with using a

hand tap under power but only do this with a hand-held tapholderwhereyoucanquicklyletgoifthetapstartstostickYou can also getmachine taps thatwill cut a thread under

powerbyscrewingthroughthejobwithoutstopping

Spiralflutetap

SpeedsforTapping

Tappingspeedsshouldbe low lowbackgearspeedshouldbefineWhenyouhavetappedtheholetodepthorrightthroughtheworkpiecestopthelatheandspinthetapoutbyhandThiswillbequickerthanreversingthelathe

ThreadingfromtheTailstock

For small taps you can use the sensitive drilling attachment(seeChapter11)orifthetapislargeryoucoulduseaslidingtapholderThiscanbeassimpleasachuckmountedonataperat one endwith a parallel hole through the chuck shank ThechuckthenslidesonabarheldinthemaintailstockchuckForlargetapsyoucanuseatommybartostopthetapholderfromturningbutthetommybarshouldnotbesolongastofoulthelathebedoranyotherpartofthemachineifyouhavetoletgoInfactitisfarsaferifyoudonotusethetommybartothreadunderpower

DIES

Dies also come in carbon steel andHSS versions The outsidediameterofadieoftenvarieswiththesizeofthethreadbeingcutalthoughthediameterwillbetooneofasetstandardDiesusually have themakerrsquos name and the thread details on thefrontof thedieThis is theside that ispresented to theworkThediewill havea short lead-in if this isnot requiredon thefinishedthreadyoucanreversethedieanditwillcleanuptoashoulder

SlidingtapholderSlidingdieholdersarealsoavailable

When cutting a thread especially a small one it pays tomaketheinitiallengthofthreadlongerthanthatrequiredThisissoyouhaveabitat thefronttoplaywithtogetthethreadright Then you can part off the excess length leaving a goodthreadoftherequiredlengthDies are usually split so you can adjust them to cut a size

threadIdeallyyoushouldhaveadieholderforeachdiesoyoucansetthedietocutsizewithouthavingtoresetiteverytimeyouchangethedieThedieshouldbesetsothatitcutsasizethreadinonepassDie nuts are often hexagonal in shape They are used to

cleanupanexistingthreadthat isdamagednot tocutanewthreadfromscratchFor each thread you are going to cut you should make a

home-madegaugetappedwithyourowntapWhenyoucutthethreadanditfitsthisgaugeyoushouldthenhaveagoodbutnottightorloosethreadYoushoulduseatailstockdieholderwithaslidingbodywhen

threadingfromthetailstockasthiswillholdthedietruetothethreadIdeally the tailstock die holder should be knurled and also

haveatommybarholeforeaseofuseThe speed for threading with a die in the lathe should be

quitelowamaximumof60rpmshouldbefineformostjobs

SCREWCUTTINGATHREAD

Whilecuttingathreadwithtapsanddiesisperfectlyadequatefor most applications the ability to cut an accurate screwthreadbyusingthelatheisaveryusefulfacilitytohaveIfthethread is large or non-standard taps and dies may not beavailable or they may be so expensive as to be out of thequestionforuseintheamateurrsquosworkshopVariouspitchesofthreadcanbecutbythesimpleexpedient

of changing the configuration of the change gears or alteringtheleversonthescrewcuttinggearboxifoneisfittedWewillconcentrate on a lathe with change gears if you have ascrewcutting gearbox please refer to the manufacturerrsquoshandbookMost lathes that youwill comeacross are likely to have an

imperialpitch leadscrewThiswillbeapitchofsomany teethper inch (TPI) Typically this will be 4 or 8 TPI although otherpitchesareavailableForourexamplewewillbeusingalathewithan8TPI leadscrewandasetofchangewheelscomprisingthefollowingnumbersofteeth2times202530353840455055606570and75

SETTINGUPTHECHANGEGEARS

Letrsquostakeatypicalthreadpitchof20TPIForeveryturnofthemandrel the leadscrew needs to move forward 120in Thismeans we have to set the change gears so the mandrel toleadscrewturnratio iscorrect Inpracticethemandrelgear islikely tobe20 teethand this is unlikely to change nomatterwhat thread we are cutting This means we will change theleadscrew gear which has to have the correct ratio to themandrelTheTPIwewishtocutis20usingaleadscrewwithapitchof

8TPI20dividedby8givesusaratioof251Thismeansthatthe mandrel gear needs to rotate at 25 times the leadscrewgearAsthemandrelhas20teeththeleadscrewgearneedstobe25times20teethwhichisa50toothgearInpracticea20toothgearanda50toothgearmaybetoosmalltotransferthedrive from the mandrel to the leadscrew and intermediategear(s)willneedtobeusedThese gears are called idler gears and they can have any

number of teeth Youmay think these idler gears change theratio of the mandrel to the leadscrew but they do not Theysimply transfer the drive from the mandrel gear to theleadscrew and the ratio stays the same This concept can behardtograspsoIwilltrytoexplainitsimplySay the mandrel gear does one turn This makes the idler

gearorgearsmoveexactly20teethandthisinturnmovestheleadscrewgearexactly20teethAsyoucanseetheratiodoesnotaltertheleadscrewgearmoves20teethforevery20teeththemandrelgearmovesandtheratiostaysthesameThistypeofset-upisknownasasimplegeartrain

Simplegeartrain

Compoundgeartrain

Letuslookatanothercommonthreadpitch32TPITheratioofleadscrewtoTPIis41(8times4=32)Sotheleadscrewgearneeds to be themandrel gear 20 teeth times 4 = 80 teethLookingattheavailablegearswedonrsquothavean80toothgearThismeanswewillhavetouseadifferentmethodtogetour41ratioWithamandrelgearof20teethwecouldusea40toothto

give us a ratio of 21 We are now halfway there but needanotherpairofgearswitha21ratioWedohavea30anda60

toothgearsothiswouldgiveusoursecond21ratioWecouldnot set these gears up as in the previous example howeversince the two intermediate gears would just act as idlers andtheratiowouldbe2150percentoutfromwhatisrequiredWhatwewouldhavetodoismountthe40toothandthe30

tooth gears on the same spindle so they rotate at the samespeedaseachother(The20toothgearmustdrivethe40toothgearandthe30toothgearmustdrivethe60toothgearinthisorder)Thiswouldgiveusthecorrect41ratiothatweneedAswehavemountedtwogearsononespindlethisisknownasasinglecompoundgeartrainDependingonyourlatheyoumayneedanidlergearbetweenthe30toothgearandthe60toothgearAgainthiswillnotalterthegearratiosYou can also have double compoundgear trainswhere two

lots of gears are mounted together on two spindles This istaking us into complicated territory however and I will referreaders to the screwcutting chart provided for their particularlathe Ifyour lathedoesnotcomewithascrewcuttingchartasearchon the Internet should findone that you candownloadandprintoutThemost likely application of double compound gear trains

would be to cutmetric threads with an imperial leadscrew orimperialthreadsover60TPII have tried to keep this explanation of setting up

screwcutting gears simple and the maths to a minimum Theexplanationgiventogetherwiththescrewcuttingchartforyourlatheshouldbemorethansufficienttogetyougoing

ExternalscrewthreadtoolmadefromaCoventry

diechaser

CUTTINGTHETHREAD

The speed for screwcutting should be about mid-back gear ifyouhaveitpreferablysomewherearound30ndash40rpmatmostTherearetwomainmethodsofscrewcuttinginthelatheThe

firstoneinvolvesthetopslidesetparalleltotheworkandintheothermethodthetopslideissetonanangletothework

Externalsinglepointscrewthreadtoolsettinggauge

Cuttinga20TPIThreadwiththeTopSlideParallel

For a 20 TPI Whitworth thread the pitch is 0050in and thethreaddepthisaconstant064ofthepitchsothethreaddepthis 0050 times 064 = 0032in This is the depth the cross slideshouldbewoundinWhilethedepthofthreadis0032inyoualsoneedtomove

the top slide forwardat eachpass Fora standardVee threadthisneedstobehalfthein-feedofthescrewcuttingtoolsoyoumovethecrossslideinby0010inandmovethetopslidealongbyhalfthis0005in

Cuttingascrewthreadwiththetopslidesetparalleltothelathe

Cuttingascrewthreadwiththetopslidesetatanangletothelathe

Theendresulta20TPIfinishedthreadbeforetidyinguptheendandundercutting

Cuttinga20TPIThreadwiththeTopSlideatanAngle

This angle will vary according to the thread being cut but itshouldbeabout1degree less thanhalf the includedangleofthethreadforaWhitworththreadof55degreesforexampletheangleshouldbehalfof55degreesminus1degreegiving265degreesNotethattheangleistakenwiththetopslidesetat90degreestotheworkWiththetopslidehandlefacingyou(at90degreestohowit isnormallyused)rotatethetopslidethe required number of degrees (265) to the right Beginnersoften rotate the top slide 265 degrees to the left from thenormalpositionwhichwouldgivean included threadangleof127degreesThisisclearlywrongBecausethetopslideissetonanangleyouwillneedtofeed

thetopslideinfurtherthanifthetopslideissetparalleltothelatheYoucan findthe increaseddepthof threadbyusingthefollowingformula

c=bcosineofA

whereAistheanglecalculatedathalftheincludedthreadangleminus1degreegiving265degreesb is thedepthof thread(forWhitworththreadsthisis064timesthepitch)andcisthecalculatedangulardepthofthreadFor a 20 TPIWhitworth thread the pitch is 0050in and the

threaddepthisaconstant064ofthepitchsothethreaddepthis0050times064=0032inThecompensateddepthofthreadisthen0032individedbythecosineof265degrees=00357

UsingtheThreadCuttingIndicator

With an 8 TPI leadscrew if the thread being cut has an evennumber of threads the leadscrew can be engaged at anypositionof the threadcuttingdial indicator If the thread isanoddnumberyoushouldusethesamenumberoranyalternatenumberthatisoneorthreetwoorfourForthreadswithahalfpitch always use the same number For metric threads orpeculiar numbers do not disengage the clasp nuts withdrawthescrewcuttingtoolandreversethemotoruntilthetoolgoesback to the start If the thread is an exact multiple of theleadscrewtheclaspnutscanbeengagedatanypositionIfindoubtalwaysengageatthesamenumberoneIttakes

verylittletimetotraversetheextradistancerequiredFor leadscrews other than 8 TPI please refer to your lathe

manual

AcknowledgementsandUsefulContacts

I would like to thankMy TimeMedia Ltd (Publishers ofModelEngineer and Model Engineersrsquo Workshop) Ken Wilson TonyJeffreeandTranswavePowerCapacitorsLtdfortheuseoftheirphotographs

USEFULCONTACTS

UnitedKingdom

ArcEuroTradeLtd10ArchdaleStreetSystonLeicesterLE71NATelephone01162695693Fax01162605805EmailinformationarceurotradecoukhttpwwwarceurotradecoukSuppliersofmachinetoolsandaccessories

ChesterMachineToolsHawardenIndustrialParkHawardenChesterCH53PZTelephone01244531631EmailsaleschestermachinetoolscomhttpwwwchestermachinetoolscomSuppliersofmachinetoolsandaccessories

CowellsSmallMachineToolsLtdTendringRoadLittleBentleyColchesterEssexCO78SH

Oiler(G)Motor(H)Tumblergearoperatinglever(I)Headstock(J)Backgearoperatinglever(K)Mandrelnose(L)Left-handleadscrewbearing(M)Leadscrew(N)Halfnutoperatinglever(O)Toolclamp(P)Topslide(Q)Crossslide(R)Saddle(S)Apron(T)Carriagehandwheel(U)Screwthreadindicator(V)Lathebed(W)Rack(X)Tailstock(Y)Tailstockhandwheel(Z)Right-handleadscrewbearing

AnearlyMyfordlatheAlthoughverybasicitcandoalotofusefulworkintheworkshopespeciallyiftimeisspentonmakingafewsimpleaccessories

This book will show you how to use the lathe safely andeffectively in your workshop but first you should ensure thatyou are familiar with the main parts of the lathe and theirterminologywhichmaybefoundonpage9Chapter1ofthisbookisaboutchoosingalathewhatsizeof

lathe to buy the different types available desirable featuresandwhetheryoushouldbuyneworsecond-handChapter 2 covers installing a lathe how to lubricate it and

maintain it in good condition and advice on general safety inyourworkshopwithparticularemphasisonhowtousea lathesafelyChapter3will lookatthematerials fromwhichcuttingtools

aremadeaswellastheirbasicshapeandgeometryThenwe

willlookatselectingsuitablespeedsandfeedsChapter 4 dealswith sharpening lathe tools andhow to set

themupinthelatheChapter 5 covers the different types of chucks how to use

themandsetworkupaccuratelyinthemChapter 6 teaches you basic turning between centres and

then introduces turning with the work mounted on the lathefaceplateChapter7isaboutholdingworkinacolletandhowyoucan

make and use several different types of mandrel forworkholdingChapter 8 explains how to turn a taper using the top slide

theuseoffixedandtravellingsteadiesandmakingaformtoolChapter9explainshowtousedrillsandreamersinthelathe

includinghowtoselectthecorrectspeedsandfeedsChapter 10 shows the different ways to bore holes in the

lathewiththeworkheldinachuckmountedonthefaceplateorheldonthecrossslideChapter 11 explains how to use knurling tools and radius

turning tools as well as making simple form tools and basicproductionmethodsChapter 12 shows you how to use taps and dies to cut

internalandexternal threads in the lathe Italsoexplainshowto set upa simplegear train and cut a screw threadwith thehelpofascrewcuttingdialindicator

1BuyingYourFirstLathe

WHATSIZEOFLATHEDOIREQUIRE

ThefirstthingtoconsiderwhenbuyingalatheisthesizeoftheworkthatyouwanttodoWhatisthelargestdiameteryouwillwanttoturnonitandwhatisthelongestlengthyouwillneedtoturnA3frac12times18in(90times457mm)lathewillallowamaximumdiameterof7in (178mm) tobe turnedover the lathebed thelatterfigureisknownastheswingInpracticethoughthisisatheoreticalmaximumas it is stillnecessary toholdandclampthe article being turned The swing over the cross slide isusuallymuchsmallertypically2in(50mm)Many lathes however aremanufacturedwith a gapbed at

the headstock end to enable short items of a large diametersuchaslocomotiveortractionenginewheelstobeturnedLathes are also sometimes available as standard and long

bed lathes The long bed lathe as the name suggests allowslongermaterial to be turned within the capacity of the latheWhen turning longermaterial the diameter will be limited bytheswingoverthecrossslideThiswillbealotsmallerthantheswingoverthebedIfbuildingamodelsuchasatractionengineoralocomotive

the deciding factor for the size of lathe is likely to be thediameterof the largestpairofwheels thatneed tobe turnedBefore deciding on the size of lathe required you shoulddetermine the size of the largest diameter and the longestlength of material that needs to be turned Another factor indeterminingwhat lathe tobuy is theavailabilityof sparesand

accessoriesisthecompanystilltradingwillitstillbetradinginthe future and are there large amounts of secondhand partsandaccessoriesavailablefromtooldealersoroneBay

Atypicalinvertertoconvert240voltssinglephaseto240volts3phase

LATHEELECTRICS

Single phase electric is where the lathe plugs into the mainssupplyinyourhouseThemotorwillhavetheusualliveneutraland earth leads Lathes supplied for factory use usually havethree phase motors and require three live wires each of adifferentphaseThinkofaphaseasan incomingwaveon theseashore three successive waves make up the three phasesneededEachphaseisthesameastheprecedingonebuttheyareoutofsyncandallpeakatadifferenttime

Aforwardreversecontrolboxforaninverter

Convertersandinverters

Youcan runsome3phasemotors fromasinglephasesupplyviaaconverteroraninverterThemotor informationplatewillusuallysay240volts440voltsif it iscapableofrunningonaninverter Inside the motor there will be changeover tags tochange the motor from 440V down to 240V Follow theconverterinverter manufacturerrsquos instructions for furtherinformation It isnotusuallyverycomplicatedto runa240V3phasemotor from an inverter and thiswill give a quieter andsmoother running motor than a single phase supply canprovide This usually requires some simple programmingexplainedintheinverterrsquosinstructionsanditusuallytakesfiveminutestogetthemotorworkingproperly

ThismotorispartoftheinverterpackageshowninthepreviousillustrationNowiringisinvolvedasthemotorleadplugsstraightintotheinverterbox

Theinverterrunsataconstantvoltagebutthespeedofthemotor will change as the frequency is raised or lowered Isuggest limitingyour inverter from full speed tohalf speed sothatthefanstillcoolsthemotorandstopsitfromoverheatingyoucanthenusethebeltstochangethemainspeedstepsasusual(Ifyoumustuseveryslowrunningitispossibletoaddaseparatefansuchasacomputercoolingfantogiveconstantairflow) Most inverter suppliers offer a forwardreverse andspeedcontrolboxthatcanbesetupinaconvenientpositiononthe machine These are well worth fitting for convenience inuse

Thisinverterisdesignedformountingonthefrontofthelathe

While inverters are designed to run only onemachine youcangetconverterstopowermorethanonemachineatatimeDependingonthesizeandpoweroutputconverterscostaboutthreetofourtimesasmuchasaninverterTherearetwomaintypesofconverterRotaryconvertersare

designedtorunmorethanonemotoratatimeThisis ideal ifyouwanttorunmorethanonemachineortwomotorsononemachineforexamplethemainmachinemotorandperhapsanauxiliary motor that drives the machinersquos coolant pump orpowerfeedsystem

Arotaryconvertercapableofpoweringmorethanone3phasemotor

ThesecondtypeisthestaticconverterwhichisdesignedtorunonemotoratatimeThereisofcoursenothingtostopyouusingthestaticconverteronmorethanonemachinebyfittingasuitablefemaleelectricalconnectortothestaticconverterandmatchingmaleconnectorstotheindividualmachinesThiswayyoucanconnectthestaticconvertertoonlyonemachineatatime

Thisstaticconverterissuitableforpoweringone3phasemotorIfyoufitasocketontheoutputhoweverdifferentindividualmachinescanbepluggedintoitoneatatime

Theelectricalloadingonrotaryorstaticconvertersmustnotexceed theirmaximumrating If indoubton the loadcapacityneeded to run your machine(s) you should consult the

manufacturerorsupplieroftheconverter

AnearthleakagetripisidealforquicklyeliminatingamotorwheretheelectricalinsulationisbreakingdownItisusefulfordetectingcertainelectricalearthingfaultsbutshouldnotbeusedasaguaranteeofelectricalsafety

Simpleelectricaltestingandsafety

Whenbuyingasmallsinglephasesecondhandlathetakewithyouanearth leakage testerof the typeused for lawnmowersandothergardentoolsIonceboughtaUnimat3lathetookithomeandpluggeditinItkeptblowingtheearthleakagetripinthefuseboxeventhoughithadworkedperfectlyatthesellerrsquoshouseIsolditonatalossbutthebuyerdidknowtherewasaproblemwiththeelectricsIt is most important that the metal parts of any lathe are

connectedtotheearthwirewhichisinturnconnectedtoearthMake sure that themotor frame is also connected toearthassome motors have dampening rubber mounts that insulatethem from themachine itself If in doubt about any aspect ofelectricalinstallationpleaseconsultaqualifiedelectrician

Acontinuousbedisidealwhenworkingwiththefaceplateorwithcollets

LATHEBED

Thelathebedisthebackboneoftheentirelatheandisthepartthat is mounted on the bench or stand There are two maintypesoflathebedtheplainbedandthegapbedTheplainbedisusuallycontinuousallthewayalongitslengthwhilethegapbedhasas itsnamesuggestsagap in thebedThis isnotaliteralgapbutasteppedsectionthatallowsbiggerdiameterstobeturnedthanyouwouldotherwisebeabletoturnonaplainbed latheThisgap isameansofmakinga lathesmaller thanwouldberequiredforaplainlatheabletoturnasimilarsizeof

componentSome continuous lathe beds have a section next to the

headstock that can be removed to increase the diameter thatcanbeturnedThisfeatureisusuallyonlyfittedtolargerlathessuchasaremostlyfoundinfactoriesSome lathes have hardened beds although most are just

plaincast ironTherearethreemaintypesofbedwayscalledshearstheplainflatbedwithsquarewaysabedwithaflattopand a 60 degree dovetail at each side and a bedwith raisedandinvertedVeewaysOnthelastofthesethetailstockusuallyrunsononesetofVeesand thecarriageonadifferent setofVees resulting in lesswear to themain slidesWidebedsarebetterandmoreaccurateasthelathecarriageislesslikelytotwistonawidebed

Close-upviewofatypicallathebedwithagapAgapbedlathehasalargerturningdiametercapacitythantheequivalentsizedcontinuousbedlathe

Someveryearly lathessuchas thosemadebyDrummondhad a round bed Although they worked well there is noadjustmentforwearinthelathebed

TheMyfordrangeoflatheshasasquareformofbed

ThistypeofbedhasaflattopwithaninvertedVeeateachsideTheVeesareusuallysetat60degreesbutcanvarywithdifferentmakers

The Unimat SL lathe was sold for many years and manysecondhandexamplesarestillavailableThismodeldiffersfrommostlathesinthatithastwosteelbarsasabedThisisnotaproblemhoweverastheUnimatisintendedonlyforverysmallandlightweightmodel-makingworkandthereistheadvantagethatthebedcanbereplacedbyfittingnewbarsWhen buying a secondhand lathe it is most important to

checktheconditionofthebedYouneedtomakesurethebedis reasonably free from dings rust and hacksaw marksHacksawmarksneartheheadstockareoftencausedbysawing

offworkwhile it isheld inthechuckdingsareusuallycausedbydroppingthechuckonthelathebedwhenscrewingitonoroffthemandrelAsimplechuckboardplacedonthebedwhilefittingorremovingthechuckwillprotectthebedItisalsoidealfor protecting the bed when filing or hacksawing work in thechuck

AlathebedwithraisedandinvertedVeesThecarriageusuallyslidesononesetofVeesandthetailstockslidesontheother

AmodernChineselathebedwithaninvertedraisedVeeThecarriageandtailstockusuallyslideonthesameVee

Wear ismost commonly found at the headstock end of thelathe as a result of machining many short components andrelatively few long ones Make sure the lathe carriage isproperlyadjustedattheheadstockandthenrunitalongasfaras you can towards the tailstock The carriage should bereasonablyfreebutnotlooseallthewayalongthebed

OldroundbedDrummondlathesarestillavailablesecondhandThisparticularexampleistreadledriven

AflatbedlathewithsquarebedwayssuchasaMyfordcanbe checked for wear on the lathe bed using amicrometer orvernierCheckovertheworkingpartofthelathebedonwhichthe carriage slides rather than the part that is not used forguidance Check both the width and the thickness of the bedwaysThetailstockshouldalsobeagoodslidingfitonanyguiding

surfaces Wear is most likely to be found on the tenon thatslidesbetween thebedwaysAworn tenoncouldprobablybereplacedbutthereisnotmuchyoucandoifthetenonguidesarewornTheonlyway to fixawornbed requiresacompletebedregrindThisislikelytobeexpensivesoitwouldbebettertolookforanunwornlatheDecentunwornlathesareouttheresincemanymodelengineersmayhaveboughtthemnewfortyorfiftyyearsagoandhardlyusedthem

TheUnimatSLisaverypopularsmalllatheItsbedconsistsoftwosteelbarsthatcanbereplacedveryeasilywithsilversteeliftheygetwornormorelikelywhentheygetrusty

Asimplewoodenchuckboardwillprotectthelathebedfromdingsandhacksawmarks

LATHEHEADSTOCK

Theheadstockisthelargecomponentmountedattheleft-handside of the lathe bed It needs to have good bearings An all-gearedheadwillalmostcertainlyhaveballorrollerraceswhilethe older type of lathe for amateurs may well have plainbearings either phosphor bronze or whitemetal These areperfectlyadequatebutyoushouldmakesurethere isnowearinthemSomelathesalsohaveamandrelthatrunsdirectly inbored holes in the cast iron headstock casting Plain bearingswillbeperfectlysatisfactoryas longasadequate lubrication isused

Close-upviewofaMyfordheadstockonanML7RNotethelargebronzebearingatthefrontTheearlierML7latheshadwhitemetalbearingsalthoughtheC7capstanhadbronzebearingsandahardenedlathespindle

Tocheck forwear in the lathersquosbearings fitachuck to themandrelandputadialtestindicatorontopofthechuckGentlytry levering the chuck up and down by using a steel bar orsimilarheldinthechuckYouarelookingforminimalmovementhereespeciallyonaheadstockfittedwithballraces

CheckingthelathebearingsforwearAnymovementupanddownindicateswearinthebearing

The mandrel is mounted in the headstock and is usuallythreaded to take a chuck or faceplate The lathersquos mandrelshould not move back and forth in the bearings If it doeshowever itwillprobablybepossibletoadjust ittocorrectanyendwise movement The mandrel should not be too stiff butshouldturneasilybyhandWhentestingalathemakesuretheheadstockbearingsare

correctlyadjustedsothatwherepossiblethereisnoplaySeta tool up take a trial cut alonga length of bar and check forchatter If you are using a correctly set tool and a suitablespeedchatterisasuresignofwornbearings

Manylatheshaveathree-orfour-stepdrivepulleyasthesecondstageofthedrivechain

POWERDRIVE

Manylatheshaveathree-orfour-steppulleyonthemandreltotake the drive from a similar pulley on the countershaft Thecountershaft is in turn driven from the motor which is oftenmounted at the back of the headstock and completes theintegral drive system that is so popular on most amateursrsquolathes

Thisparticularlathehasatwo-stepmotorpulleyandcountershaftwhichdoublestheavailablespeeds

SpeedchartonthebeltguardofaMyfordML7Rlathe

AfewlatheshaveaclutchfittedasstandardorasanoptionalextraTheclutchsaveshavingtostartandstopthemotorwhileitisrunningThishelpstostopwearandtearonthemotorandelectricalsystemAdifferenttypeofclutchsystemtheTriLevaspeedselector

wasonlyfittedtoMyfordML7orC7lathesThishasthreeleversfor setting threedifferent speedsDependingon the leveryoudepressyougetahighmediumorlowspeedIfyoupressoneof the levers downwhile another is right down the first leverwilldisengagethesecondsostoppingthemandrelfromgoinground If the lathe is switched off and all three handles aredepressed the mandrel is locked preventing rotation This isusefuliffilingorhacksawinginthelathe

TheclutchisnormallymountedinsidethelargecountershaftpulleyItisusuallyoperatedbyaleverattheright-handsideoftheheadstockattachedtoapushrodthatpassesrightthroughthecountershaft

TheMyfordTriLevaattachmentwillonlyfitML7andC7lathesandisnotsuitableforML7RorSuper7lathes

Therehasbeenatrend inrecentyearstodoawaywiththecountershaftandpulleysystemandtoreplacethemotorwithavariable speed one with an electronic controller This isacceptable except that at low revolutions it does not providethe torque that can be obtained from a countershaft systemThereisalsothedisadvantagethatthereisnowaytodrivethelatheifthecontrollercircuitboardfailswhereasyoucanjustfita new one if the belt breaks The board could of course befixed provided that a circuit diagram is available and theelectronic components can be identified Sometimes thecomponents are marked with internal house numbers ratherthan commercially recognized part numbers that can beorderedasareplacementfromacatalogueSomeboardsmighteven have the identification marks removed to make repairsalmostimpossible

ThethreadedendofalathemandrelisdesignedsothatthechuckbackplaterunstrueIfthechuckmountingfaceofthebackplateismachinedinsituthechuckshouldruntrueaswell

CHUCKMOUNTINGSYSTEMS

The threaded lathe mandrel nose is not by itself a suitablelocationforachuckorfaceplatesothenoseisusuallygivenaturned register on which to locate the chuck The chuck isscrewedrightontothemandrelovertheregisterandbuttsuptoaturnedcollartokeepthechuckrunningtrueTheothersideof the mandrel collar butts up against the main headstockbearingwhichusuallyactsasathrustfaceThemandrelisusuallyboredthroughandmachinedtotakea

MorsetapercentreforturningbetweencentresDonotputyourfingerineitherendofthemandreltocleanitwhilethelatheisrunningAneasywaytocleanthetaperintheheadstockiswithabottlebrush often sold in chemists to cleanbabiesrsquo bottlesAnalternativeisasoftfeltshotgunbrushdonotuseonemadefromwire

ThislathehasaplainregisterAccuracyreliesonthelathechuckbeingagoodfitontheregister

There are various systems of chuck mounting in useespeciallyon the larger lathesTheproblemwith thescrew-ontype with a register mentioned above is that the chuck orfaceplatecanunscrewwhenthelatheisrunninginreverseTheonly timeyoushould run this typeofmandrel in reverseveryslowly and without taking a cut is if you need to return thescrewcuttingtooltothestartofthethreadyouarecuttingAlternativespindlenosescanbeaplaindiscwitharegisterto

boltthechuckontooracamlockwherethechuckisheldontightlybyturningstudstolockthechuckontothemandrelTheplain discwith register relies on having chuckswith amatingregistertoworkproperly

AnAmericanstandardCamLockchuckmountingbackplateandCamLockchuckplatefittedtoachuckTheyareusuallyfittedtolargerindustriallathes

TheAmericanDstyleCamLocksystemeithertakesachuckor faceplate directly or it has a backplate that can have aregisterturnedonittosuittherequiredchuckAlthoughmanylathe mandrels with Cam Lock fittings have six holes thematchingchuckorfaceplateoftenhasonlythreelockingpinsThe advantage of both of the last two systems is that they

canberuninreversewithoutthechuckcomingoffthemandrel

Theleadscrewisdrivenfromthemandrelviaageartrain

SCREWCUTTINGGEARS

The left-hand end of the mandrel will often have a gearmountedonittodrivethechangewheelgearsandleadscrewThe mandrel gear usually drives a pair of gears called

tumblergearswhicharemountedona leveratthe leftoftheheadstock The direction of the leadscrew can be changed bybringingeitheroneortheotherintogearbyraisingorloweringaleverThereisusuallyacentralneutralpositionwhereneithergearisinmeshThissaveswearonthelathechangewheelsandleadscrew bearings as well as reducing noise while workingMandrelandtumblergearswillbediscussedfurtherinChapter12whenwesetupascrewcuttinggeartrain

A set of changewheels usually comprises about a dozengearsbutthiscanvarydependingonthemanufacturerThesechangewheels which take the drive from the tumbler gearsdown to the leadscrew are mounted on moveable studs toensurethegearsareinmeshwitheachotherDependingonthenumber of gears in the train the leadscrew will turn eitherclockwiseoranti-clockwiseThedirectionof the leadscrewcanbe reversed using the tumbler gears to enable right-hand orleft-handthreadstobecut

Oftentherearetumblergearsinthegeartrainthatcanreversethedirectionoftheleadscrew

YoucanusuallysetthegearstocutaveryfinepitchsothattheleadscrewactsasaselffeedwhenturningfromthesaddleIf you anticipate the need to do any screwcutting check thatthesuppliedscrewcuttinggearswilldotherangeofpitchesyourequire It has been known for certain lathes to be unable tohandle somecommonpitches a typical examplebeing26TPI(teeth per inch) A pitch of 26 TPI is often needed to repairmotorcycles and bikes made before the introduction ofmetrication

MakesurethatafullsetofchangegearsisincludedwiththelatheIfnottheyarereadilyavailablesecondhand

LEADSCREW

The leadscrew ismounted at the front of the lathe there areusuallybearings to support the leadscrewateitherendof thelathe bed It is used tomove the lathe saddle along the bedeither for a self acting feed or for screwcutting Some lathesalso have a graduated handwheel mounted at the right-handendoftheleadscrewforturningthemandrelbyhandSome of the larger lathes also have a separate feed shaft

whichisusuallyaplainroundshaftwithakeywaycutalongittodrivethesaddleusingafinefeedThissaveswearandtearontheleadscrewwhichisthenonlyusedforscrewcutting

Mostleadscrewscanhaveagraduatedhandwheelmountedontheright-handendoftheleadscrew

SCREWCUTTINGFACILITIES

Ausefulfeatureonanylatheistheabilitytocutscrewthreadsof different pitches Leadscrews come in different pitches acommon one being 8 TPI but many variations are fitted todifferent lathes including leadscrews with a metric pitch It isawkward tomachinemetricscrewswithan imperial leadscrewandviceversaSometimesmetricconversionsetsareavailablebuttheycanbehardtofindareusuallyexpensiveandrequirethe lathe to be changed over often using 127 tooth gearwheels This figure is derived from multiplying the metricequivalentof1in(254mm)byfivea127toothwheelisthusadirectconversiontoametricthreadonalathewithanimperialleadscrewA127 toothgear isusuallyvery large if itmatchesthepitchoftheremainingscrewcuttinggearsbutyoucouldusesmallergearswitha smallerDP (diametralpitch)but stillwith127 teeth Youwould also need amatching gear of say fiftyteethtogiveyoua2541ratio

Thislathehasbothaleadscrewforscrewcuttingandadriveshaftforthesaddleandcrossslidefeeds

Ascrewcuttingdialindicatorusuallymountedtotherightofthe carriage is a useful feature This is a small dial withdivisionsmarkedonitmountedonashaftTheotherendoftheshafthasagearthatmesheswiththeleadscrewandmakesthedial go roundWhen the clasp nuts are engaged the carriagemoves and as the gear moves at the same speed as thecarriagethedialstopsgoingroundWhen you engage the clasp nuts on the leadscrew the

positionwhereyouengagedependsonthepitchofthethreadbeing cut Some thread pitches allow you to engage at anydivision of the dial while others need to be engaged at aparticularpositionof thedialTheuseof thescrewcuttingdialindicator will be covered in Chapter 12 When using the finefeedyoucanengagetheclaspnutsatanymarkedpositiononthedialsoavoidingweartotheclaspnuts

AtypicalscrewthreaddialindicatorThisoneisengagedanddisengagedbylooseningtheboltandengagingthedrivegearwiththeleadscrew

LATHESADDLEANDAPRON

The saddle is thepart that slides on top of the lathebedandusually has the cross slide and top slide mounted on it Theapron ismounted to the frontof the saddleYoushouldmakesure there isnoplay in the saddle either sidewaysorupanddownandthatittravelsfreelyfromoneendofthelathebedtotheotherwithnotightspotsAtthefrontnearesttheoperatorthereisusuallyapairofclaspnuts(thesearesplitnuts)Thesecan be engaged or disengaged from the leadscrew forscrewcuttingormovingthesaddlealongwiththeleadscrewOncheaper lathes there is usually a solid nut that cannot bedisengaged

ThelathesaddleslidesalongthelathebedTheapronisboltedtothefrontofthesaddle

There is often a rack at the front of the lathe bed thatmatches upwith a handle and gears on the lathe apron Thiscan be used to move the carriage along the bed withoutwearingouttheleadscrewSomelatheshavethecarriagefeedwheel on the right but others have it on the left where hotswarfcanfallontoyourhandsThecheaperlatheshavenorackandrelyontheleadscrewtowindthecarriagebackandforth

ATee-slottedcrossslidemakesthesmalllathemoreversatile

CROSSSLIDE

On top of the carriage is the cross slidewhich canbewoundbackandforthacrossthelathebedWhenusingthecrossslideforfacingacrosstheworkthecarriageshouldbelockedtostopitmovingalongthebedLathesforamateurusearemorelikelytohaveaTee-slottedcrossslidewhilelargercommerciallathesare unlikely to have this facility The Tee-slotted cross slide isveryusefulespeciallyifyoudonrsquothaveamillingmachineYoucanboltworktothecrossslideformachiningusingacutterinthechuckorforboringworkpiecesthataretoolargetoswinginthechuckZero settingdials aredesirable for both the cross slide and

thetopslideTheyallowyoutosetthedialtozerowhichmakesiteasiertomeasuretheamountyouaretakingoffwithonecutInusewindthetooluptotheworkandtouchonsetthedialtozeroandwind the toolbackoff from theworkYounowknowwherezeroisonthetoolandcantaketherequireddepthofcut

withouthavingtoworkitout

Zerosettingdialsmaketurningandscrewcuttingtodepthveryeasy

Apairofzerosettingdialsreadytofit

LathescanbepurchasedwithimperialormetricfeedscrewsMostmodeldesignsareimperialbutmetricismakingheadwayandthismaywellbethewaytogoBewarelatheswithimperialfeedscrewsandmetricdialsTypically thesewillhavea funnynumber of handwheel divisions rather than a whole numberMostofthelathesyoumightcomeacrossareunlikelytohavea

power cross feed for facing This does notmatter as you caneasilywindthecrossslideacrossbyhandTheonlytimeIhavefound a power cross feed to be of use is when I had to faceacross a faceplate to true it up I have trued up similar sizefaceplatesbyhanditjusttookalittlelonger

Thetopslideismountedonthecrossslide

TOPSLIDE

ThetopslideismountedontopofthecrossslideThetopslideisnormallysetat90degreestothecrossslidealthoughitcanusually be swivelled around to various angles for turning ataperanangleorforscrewcuttingSomeofthecheaperlathesdonrsquothaveatopslideasstandardbutitisaveryusefulfeatureif you can get one The top slide should be able to rotateespecially for screwcutting but the top slide handlemay foulthecrossslideincertainpositionssocheckifthisisaproblemTheturningtoolisusuallymountedonthetopofthetopslideItcan either be clamped on directly usually with packing stripsunderneathorthetoolcanbemountedinatoolholdersuchasathree-orfour-waytoolpostoraquickchangetoolpostWewilllook at tool holding methods in Chapter 4 when discussingsettingupturningtools

TAILSTOCK

The component at the right-hand end of the lathe is thetailstock This usually has a handwheel to feed a drill into theworkbut leverfeedandcapstan-style feedingmechanismsarealso available You can lock the tailstock anywhere along thebed The tailstock has a barrel inside it that can bewound inandouttogivealinearmovementtodrillaholeinworkheldinthechuckThetailstockisusuallyboredtoaMorsetaperoftenof a similar size to the headstock so it can take accessoriessuchasdrillchucksmountedonaMorsetaperItcanalsotakeacentre for turningworkbetweencentres It is important thatboth the headstock and tailstock tapers are free frommarksscratchesandburrs

AlathetailstockwiththebarrelextendedNotethatitisnotusuallyaproblemifthechuckkeyisleftinthetailstockwhilenotinuse

Adjustment is usually provided between the base and themain body of the tailstock to allow for setting the tailstock inlinewith theheadstock Tailstocks canbe self ejectingwherethetool isextractedas it iswoundbackwhilesometailstockshavea throughholeandneeda tapwithabar to remove thetool Handwheel depth graduations for drill drilling to a

particularholedepthareveryusefulbutarenotoftenincludedon the cheaper lathes although industrial lathes usually havegraduatedtailstockhandwheelsThebettermakesoflathehavea lever clamping tailstock arrangement while the cheaperlathesoftenhaveaclampingspanneroranAllenscrewclamp

Allguardsshouldbefittedinplacebeforeoperatingthelathe

MACHINEGUARDS

Thedrivemotorcountershaft(iffitted)andpulleybeltsshouldallbeproperlyguarded It isveryeasy togetcaughtup inanunguardedmachineandtheconsequencescanbequitenastyThis has never happened to me but I have seen someonecaught up in a machine and it was not very nice I dorecommend that you make sure your machine guards arecorrectlyfitted

OTHERDESIRABLEFEATURES

Digitalreadoutsareusefulonalatheastheycanshowyouhowmuch to move the handwheels and how much material hasbeentakenoffTheyarequiteexpensivebutyoucan fit themyourself if youare carefulUnfortunatelymost of the cheaperversionsdislikesolubleoilorothercoolantifyougetitintothereadouthead

Adigitalreadoutsuitableformountingonalathe

Youwillneedtwoslidesoneforeachaxis

A soluble pump for cutting fluid is useful and often comesfittedasstandardonthelargerlathesHoweveratinofcuttingoilandabrushwillbegoodenoughformostworkandthatmaysuityoufine

Solubleoilpumpsandreservoirsarereadilyobtainable

Formostjobsyoucangetawaywithsomecuttingoilabowlandabrush

TheMyfordlsquoNortonrsquostylequickchangescrewcuttinggearbox

A Norton quickchange screwcutting gearbox saves time asyou donrsquot have to set up changewheel trains A gearboxhowever considerably increases the price of the averagesecondhand lathe A Myford Norton gearbox has twenty-fourpitchesandiscontrolledbytwoleversReversingtwogears inthe Myford changewheel train gives the gearbox twenty-fourfine feeds insteadof the twenty-fourscrewcuttingpitchesThegearboxhasa setofgearsarrangedasaconeBysliding thelever along and dropping themaster gear onto the cone youcanchangethegearboxratioandsothepitch

TheconegearsinsideatypicalNortonscrewcuttinggearbox(notanoriginalMyfordone)

SeveraldesignshavebeenpublishedtomakeyourownNortontypescrewcuttinggearboxThisoneisavailablefromHemingwayKits

SPINDLESPEEDS

Thespeed rangeneededona lathedependson thework it is

requiredtodoAgoodrangeofspindlespeedsisdesirablewithnoobviousgapsWithelectroniccontrolthisshouldnotbetoomuchofaproblemIdeally a back-geared lathe would be best but this means

either a good secondhand machine such as a Myford or aBoxford or alternatively one of the larger Asian-made latheswithanall-gearedheadstock

Thisbackgeararrangementisswitchedinandoutbyturningthetoggleonthepulleyandliftingaleveratthefrontofthelathe

Backgearnormallyconsistsoffourgearstwolargeonesandtwosmalloneswhichcanbeswitched inorout toreducethespeedofthelathebyaratioofusuallyabout51dependingonthe maker to enable you to turn large diameter workpiecesThis reduction is also essential on a screwcutting lathe asotherwisethemandrelwillbegoingtoofastwhilescrewcuttingandyouwonrsquotbeable tostop in the rightplaceat theendofthethreadIf buying a back-geared lathe check that both gearwheels

havealltheirteethItisamajorjobtostripdownalatheandfitnewgearwheelsassumingtheyareevenavailableassparesCheckthelatheinallgearrangeswiththelatherunningIfa

back-geared lathe or an all-geared head is noisy it could

indicatewearitwillalsobeanuisanceinyourworkshopasnoonewants to hear a noisymachine runningNoise could be amajorproblemespeciallyifyouhaveneighboursnearbyGearedheadsusuallyhaveawiderangeofspeedsthelarger

industrial lathescangoup tospeedsof2000rpmandsmallerversionsareoftenhigher

Anall-gearedheadonamodernindustrialsizelathe

On the more usual amateursrsquo lathe there is often acountershaft usually tensioned by a lever which tightens upthebeltreadyforuseThemiddlespeedofthecountershaft isusually chosen to be about one quarter of the motor speedMost small lathes have three speeds and the back geararrangement adds another three speeds giving six in all TheMyfordSuper7rangeoflatheshavefourspeedsandbackgearmaking eight speeds but there is also a double pulley on themotor countershaft section making sixteen speeds in allalthoughtheverylowestback-gearedspeedswillrarelyifeverbeusedSomeoftheolderColchesterChipmasterlatheshavewhatis

knownasaKoppVariatordriveThis isavariable speeddrivecontrolledbyadialandthesystemworkswellbuttheVariator

isveryhardtoreplaceifthedrivefails

ThissmallCowellslatheiscapableofdecentworkandatthetimeofwritingisprobablytheonlylathestillbeingmadeinBritain

MOUNTINGTHELATHE

There are three main options for mounting a lathe benchmounting portable or on a stand Ideally a makerrsquos standshouldbeusedformountingamediumto large latheandthestandisoftenanintegralpartof larger lathesAsmaller lathesuch as a Unimat or a Cowell can bemounted on a woodenchopping board or a similar small board These lathes can beputawayinacupboardafteruseThe alternative is a workbench but these are often made

from wood which can expand or contract depending on themoistureintheairWoodisnotagoodmaterialfromwhichtomakea stand for a larger latheas itwill attractmoisture andmayexpandshrinkordistortAmetalstandisabetteroptionWewilllookatinstallingthelatheinChapter2

AnArcEuroTradeC3screwcuttinglathemadebySiegThisisaverypopularentrylevellatheandmanyaccessoriesareavailable

Amedium-sizedscrewcuttinglathesuitableforgardenshedworkshops

SHOULDIBUYNEWORSECONDHAND

Beginnerssettingupaworkshopoftenaskifitisbettertobuyanew lathe or secondhand The preceding pages should have

given some guidance but there are more points to be takenintoconsideration

Alargerindustriallathewithafoot-operatedemergencycut-offswitchandbrake

BuyingNew

Thelistoflathesuppliersincludedatthebackofthisbookwereall in business at the time of writing Most will be willing todemonstratetheirrangeofmachinesattheirpremisesorwhileattendingmodelengineeringexhibitionsPaycloseattentiontomechanical noise the general paint finish and the workingslideway surfaceswhich should begroundDoes themachinehave sharpor roughedges (Handwheelsareespeciallypronetosharpedges)The main thing to consider though is the attitude of the

supplier Were they willing to talk to you and answer yourquestionseitheratanexhibitionoroverthephoneHowlongdo they take toanswer thephonewhenyou ring their servicedepartment Do they know the answer to a simple questionstraightawayordotheyhavetogetbacktoyouIsthemanual

written in English or Chinglish (translated awkwardly fromMandarinorCantonese)There are several suppliers of new lathes inmost countries

aroundtheworldbutthemajorityoflathesaremadeintheFarEastOftensupplierArsquosmachinescomefromthesamefactoryassupplierBrsquostheyarejustpaintedadifferentcolourandhavedifferentnamesandlabelsfittedAftersales service can vary greatly Usually companies that

havebeeninbusinesslongerwillofferbetteraftersalesservicebutotherpeoplersquosexperiencescanbefoundonInternetforumsoratlocalmodelengineeringclubsUsually theAsian lathesare reasonablywellmadebut they

often suffer from having plastic gears instead of metal onesOneortwocompaniessupplymetalgearsasstandardso it isworthaskingiftheirmachineshavemetalorplasticdrivegearsSome companies also offer after-market replacement metalgears

BuyingSecondhand

There aremany good quality secondhandmachines availablebut there is also a lot of worn-out rubbish If possible take aknowledgeable friend with you when purchasing a lathe Becareful when buying at online auctions such as eBay MostsellersaregenuinebutsomearenotNeverpartwiththecashuntil youhavechecked the latheover IhaveboughtoneBaywithoutproblemsbut Iamcarefulwhat IbuyandwhofromAsmall latheforacoupleofhundredpoundsisunlikelytobreakthe bank if it is a bit of a dog but a lathe that costs severalhundredpounds is adifferentmatter ThegreenMyfordML7RpicturedthroughoutthisbookwaspurchasedfromeBayItwasbrand new the motor had never been fitted and it was abargainwhencomparedwiththeretailpriceIdidpaycashoncollectionbutIwouldhavewalkedawayif ithadnotmatchedthedescriptioninanywayWhether purchasing new or secondhand check what

accessoriescomeaspartofthepackageandwhatwillneedto

bepurchasedseparatelyEssentialtoolingcanoftendoublethecost of a newmachine if it is not included in the price whilededicatedtoolingmaynotevenbeavailable forasecondhandbargainlathe

Youshouldnowhaveanideaofthesizeoflatheyouneedthefunctionofthedifferentpartsofthelatheandwhetheryouarebuying new or secondhand In Chapter 2 we will look atinstallingthelatheandsafetyintheworkshop

2InstallingtheLatheandUsingItSafely

If you are buying a new lathe completewith delivery to yourworkshopyoucangostraighttothesectiononsettingthelatheupIfyouarecollectingthelatheyourselfhoweveryoushouldpayattentiontoafewwordsonmovingit

Ifyouhaveroomtomanoeuvreanenginehoistcanbeusedtomovemachineryaroundsafely

MOVINGTHELATHE

MOVINGTHELATHE

When going to collect your lathemake sure someonewill betheretohelpyouloaditortakesomeonewithyouUnlessitisaminiaturelatheitwillbetooheavyforonepersontoliftHelpisalsoneededwhenyougetthelathehomeLiftingthelatheoutofacarcanbeharder than lifting it in It isadvisable tohavethreepeoplewhenunloading twoat theheavyheadstockendandoneliftingthelightertailstockendYoucanrentorbuyanenginehoist fora reasonablepriceand this canmakemovingthemachineeasierIf the machine is a substantial industrial type it would be

besttohireatransportcompanythatspecializes inmachineryremovals Professional machinery removers will usually haveproperlyequippedtransporttomoveheavymachinesThiswillprobablyworkoutcheaperthanattemptingtodoityourselfbutmake sure they have insurance in place in case they damagethelatheoryourpropertyYoushouldalsoensuretheyknowithas to beput in place as required in theworkshop youdonrsquotwanthalfatonofmachinerydumpedonyourdrivewithnowayofmovingitintopositionLathesareusuallytopheavywhenbeingmovedandcantip

overifyouarenotcarefulTheMyfordML7seriesforexampleoftenhasthemotorandcountershaftboltedtothebackofthelathe bed and this type of lathewill tend to tip backwards Asimple solution is to bolt two lengths of wood about 4 times 2in(100times50mm)tothelathefeetOneboltineachendwilldoifyou canrsquot drill holes in the correct position This will stop thelathe tipping backwards and also make it easier to lift IfpossibleyoushouldremovethetailstockThisisoftenaheavylumpofmetalbutitisusuallyveryeasytoslideitofftheendofthelathebedAnyotherlargeobjectsthatcanberemovedandreplacedlaterwillmakethelathelighterandeasiertomove

Twoplanksofwoodboltedtothelathefeetwilloftenturnanunmanageablemassofmetalintoaneasilyhandledmachine

Azerovoltsswitchisessentialequipmentonanymachinetool

Wearoldclotheswhenmovingyourlatheandhaveplentyofold rags to wipe off swarf and oil Lay down old blankets ordecoratorsrsquosheetsinsidethecarandasheetofthickcardboardMDForplywoodtohelpprotectthebootareawhenslidingthelatheintothecar

AsmallishlathecanoftenbefittedintoastandardhatchbackorestatecarYoumayfindhowever thatyouhavetodotwotrips one for the lathe and accessories and another for thecabinetthelathestandsonTosaveawastedjourneyIusuallytrytofitthelathecabinetinfirstIfIthenfindthatthecabinetdoesnrsquotfitIcanstillbringthelatheandtoolinghomeknowingthat Ihave tohireavan tocollect thecabinetbutalso that IhavenothadawastedjourneyIfyouhavetosplittheelectricsforexampletotakethelathe

offthecabinetdrawadiagramoftheelectricalconnectionssoyoucanrewirethelathewhenyougetithomeAdigitalcameraisalsoagoodmethodofrecordingthewiringconnectionsbutIwouldnotrelyonthecameraaloneIf the lathedoesnothaveazerovoltsswitch itwouldbea

good idea to fit one after you get the lathe home They areavailable quite cheaply andare easily fitted If in doubt aboutyourabilitytodoelectricalwiringconsultaqualifiedelectrician

Adjustablefeetareveryusefulforlevellingupthelathe

SETTINGUPTHELATHE

Somelathesusuallythelargerindustrialoneshaveanintegral

bedandcabinetThelathecanbesettotruewithjustshimmingunderthefeetorbyadjustingthefeetOther lathes may need to be mounted level and true to

ensureaccuracywhenturningSetthebenchstandas levelasyou can in both directions using a spirit level as a guide Anycheapspirit levelwilldoas longas it isaccurateYoucantesttheaccuracyofaspiritlevelbyturningitround180degreesifitisaccurateitshouldreadthesamebothwaysOnce the stand is reasonably level youcan level the lathe

ThisinvolvesjackingorshimmingupthelatheuntilitistrueinbothdirectionsIfusingawoodenbenchputmetalplatesunderthe feet tospread the loadShimoradjust the latheuntil it isreasonablylevel

Putthespiritlevelonthecabinetrsquoslongitudinalaxisandusetheadjustablefeettolevelthelathe

Insertalengthofbarinthechuckandputadialtestindicatoron top of the tailstock end of the bar Nip the headstock endmounting bolts down first and then tighten down the tailstockendboltsAdjustorshimthetailstockenduntilthereisnosignof movement on the test indicator Next 64repeat theprocedure with the dial test indicator on the front of the barAgainyouare looking fornomovementCheckbothdirectionsagainmakingsurethereisnomovementeitherhorizontallyorverticallywhenyoutightenthelathedownAdjustorshimuntil

there is no movement in either direction when the lathe isclampeddownAslongasthebedisnottwistedthelathebedshouldnowbetrue

1Insertapieceof⅛in(3mm)packingunderthespiritlevelatthetailstockendThiswillresultinarunonthedriptrayandalltheoldoilwillruntotheendofthelathemakingiteasiertocleanup

2Placethespiritlevelonthecabinetcrossaxisandusetheadjustablefeettolevelthelathe

3Putthespiritlevelonthelathecrossaxisattheheadstockendandlevelitasbestyoucan

4Putthespiritlevelonthelongitudinalaxisandlevelalongthelathe

5Testthetopofthebarthereshouldbenomovementwhenthelatheisclampeddown

6Testthefrontofthebaragainensuringthatthereisnomovementwhenthelatheisclampeddown

Alignthetailstockbyusingadialtestindicatorintheheadstock

AligningtheTailstock

NowweneedtosetthetailstockinlinewiththeheadstockDothisbyputting thedial test indicator into theheadstockchuckandtestthetailstockboreAdjustthetailstocktowardsthefrontortothebackofthebeduntilthetestindicatorreadstrueandtighten theclampscrewsA slightdifference inverticalheightwillnotbetheendoftheworlditjustmeansthereisprobablysomeweartothebaseofthetailstockcastingbutthereshouldbenovariationfromfronttobackinthehorizontalalignmentPutalongbarbetweenthecentresandtakealightcutalong

it using a fine power feed Run along the bar a couple moretimes at the same setting to remove any push offWhen youmeasure thebar it shouldmeasure the sameatbothends Ifthe bar is larger at the tailstock end you need to reduce theheightofthebedatthefrontofthetailstockslightlyIfsmalleratthetailstockendyouneedtoreducetheshimatthebackofthe tailstockend Itprobablywonrsquotneedmuchadjustmentasslightadjustmentstotheshimoradjustersatthetailstockendwillsoonbringitintoline

Usingatestbartocheckforparallelturning

LubricatingtheLathe

You should follow the manufacturerrsquos recommendations forlubrication Usually this is thin oil for the headstock oftenhydraulicoilandslidewayoil forthemovingpartsLubricationshouldbedoneregularlyIfthelatheisfittedwithasightfeedoileritshouldshowoilinitAdjustablesightfeedoilersasusedonMyfordandsimilarlathesshouldbeadjustedsothattheoildripswhen the lathe is running but does not dripmuchwhenthe lathe is stopped The slight vibration when the motor isrunningisusuallyenoughtocausetheoiltodripToomuchoilisbetterthannotenoughoilisfarcheaperthannewbearings

Atypicaldrip-feedlubricator

UseanoilgunonalltheoilnipplesYoucangetaroundthetendencyfortheoiltogoeverywhereexceptintothenipplebyputtingapieceofwritingpaperoverthenippleandthenusingthe oil gun as normal The paper will stop the oil squirtingeverywhereThemandrelbackgearalsoneedstobelubricatedWheninusethemainbackgearisrunningontheoutsideofthelathemandrelandneedstobelubricatedoftenoritwillgethotandwearChangewheels should be lubricated with oil not grease If

youusegreaseswarfwillsticktothechangewheelsandcauseunnecessarywearTo stopswarf running through themandrelanddroppingoutontothechangewheelsputawinebottlecorkor similar into the left-hand end of the mandrel This willeffectivelystopanyswarfgettingthroughtothechangewheelsOil the saddle and cross slide and also the nipples on the

tailstock Make sure oil is showing at the edge of the slidingsurfaces A squirt of oil on the cross slide and topslide feedscrew bearing is needed as well Check the manufacturerrsquosinstructions for lubricating the rest of the lathe Follow themotormakerrsquosrecommendationforlubricatingthemotorTrytoavoidusingWD40onthelatheWhileitisanexcellent

lubricantwaterdisplacerittendstodiscolourthelathebed

Useabitofpaperundertheoilguntostoptheoilsquirtingeverywhere

AvoidingtheRustFairy

Rust canplayhavocwith a lathe quickly turning thebedandother parts into a brownmess Various sizes of plastic coverssuitable forcovering lathesareoftensold foruseasbarbecuecoversinDIYstoresAplasticlathecoverwillhelptokeeprustatbaybutmoreneeds tobedoneAbagcontainingsilicagelplacedundertheplasticcoverforexamplewillabsorbexcessmoisturesilicagelcanbeboughtverycheaplyoneBay

SilicageliseasilyobtainablefromeBay

Alternatively you can buy a vapour phase inhibitor forprotecting the lathe The vapour phase inhibitor chemical issuppliedonafeltpadinsideaplasticpotThechemicalformsaprotectivelayeroneverysurfaceBecauseitisavapouritwillfind its way into every cranny and is also used for protectingtools and accessories in tool cabinets and drawers It usuallylasts for twelvemonths ifenclosedby theplasticcoverSomemachinetooldealersareabletosellsuppliesofthisproductinsmall ready to use containers rather than in industrialquantitiesAlwayscleanthelathedownafteruseswarfwillsoonrustif

leftonalatheasitwillprobablybecleanfromturningandwillnotbeprotectedbyoilTheuseofanovencookingtrayunderthe lathe bedmakes it easy to remove swarf at the end of aturning session The tray also helps to retrieve a parted offcomponentora lost screw froma tipped turning toolAnotheralternativeistocoverthelathechiptraywithnewspaperwhenyouhave finished turning remove thenewspaper screw it upandthrowitawayWhenfittingachuckorfaceplatetothelathemakesureyou

cleanthemandrelthreadtheregisterandthefaceYoushouldalso clean the mating threads the bore and the face on thechuckorfaceplateYoucancleanthethreadandboreeasilybyusing two toothbrushes bolted back to back with spacers inbetween Make sure the Morse tapers in the headstock andtailstock are cleanbefore fitting aMorse taper accessory TheMorse taper to be fitted should be free from scratches burrsandbruisesIt is good idea tomake a chuck board for usewhen fitting

chucks to a lathe or removing them This is a piece of wood(plywood will do) that sits on the lathe bed while you arescrewingthechuckonandoffThechuckboardwillprotectthelathe ifyoudrop thechuck It canalsobeused toprotect thelathebedwhenyouarehacksawingorfilinginthelatheIf you keep your lathe clean and lubricate it regularly it

shouldlastalifetime

AlargetraywillcatchmuchoftheswarfandtheholeslettheoildrainawayUsenewspapertosoakuptheexcessoil

SAFETYINTHEWORKSHOP

RememberyouareresponsibleforyourownsafetySafetyisamajorconcernintheworkshopTherearecertain

thingsyoushoulddoandobviouslythingsyoushouldnotByitsverynatureaworkshopcanbeadangerousplaceallwecandoismakeitassafeaspossiblewhilestillallowingustoworkinit

WorkingAlone

Mostofyoureadingthisbookwillprobablybeworkingaloneinasmallworkshopgarageorgardenshed IfyougethurtyoumaypossiblybeonyourownAsapriorityIsuggestyoutakeamobilephoneintotheworkshopandkeepitinyourpocketTheability to contact your family a friend or the emergencyservicesquicklycouldsaveyour lifeKeepthephoneswitchedoff while in the workshop however as it is an unnecessarydistraction

FirstAid

FirstAid

AFirstAidboxwithcontentsisanecessityandshouldincludeaneye-bathandeyewashYoushouldparticularlylearnhowtostopbloodflowingThereareplentyofwebsitesthatwilltellyouhowtodothisCheckthemoutnowbeforeyougobackintotheworkshop

ElectricalSafety

Checkforearthcontinuitywhilethemachineisunpluggedwithavoltohmmeterfromtheearthpinonthethreepinplugtothemetalpartofthelathe(somepaintmayhavetoberemovedforareadingtotakeplace)Youshouldgetareadingofzeroohmsorabeep if themeterhasacontinuity rangeYoushouldalsobe sure that the electrical sockets on the wall are correctlyearthedIfindoubtconsultacompetentelectricianLightingandelectricheatingshouldbeonaseparatecircuit

tothemachinessoyouwillstillhavelightifthemachinestripoutPlugasmalllightintothemachinecircuitsoyouhavesomelight if the lighting circuit trips out When I go on holiday Ialwaysturnoffthefusetripsforthelightinginordertomakeitmore difficult for intruders to move about quickly Leave thehouse alarm and smoke detectors on (The house alarmmayactivateeighthoursafter theelectricity is turnedoffwhenthebatteryexpires)

Adigitalmultimeterisveryusefulinthehomeworkshop

BeAware

Bementally alert while using the lathe Avoid operations thatmightputyourhandsatriskofenteringthemovingpartsofthelathe Do not operate any lathe while under the influence ofdrugs alcohol or prescription medication that may causedrowsinessorotherwiseaffectyourability to control the lathesafelyDonotattempttoworkonalatheandtalkatthesametimeIfyouhavetotalktosomeoneswitchoffthelathebeforedoingso

KeepItClean

TheareaaroundalatheshouldbekeptfreeofobstructionsThefloorshouldbecleananddrywithanyoilorotherspillscleanedup immediately The lathe should be kept clean and tidyMachinedangerareasshouldbemarkedontheworkshopfloorand observed Workbenches placed near a lathe should be

strongandequippedwithanon-slipsafetysurfacetostoptoolsor other items rolling onto the floor a rubber car mat willsufficeA rubberdoormat on the floorwill allow swarf todropthrough in order to save you getting swarf embedded in thesolesofyourshoes

Asuitablefloormatwillallowswarftodropthroughandhelpkeepyourfeetwarminwinter

LearntoUsetheLathe

Donotuseany lathebeforeyouare familiarwith thecontrolsandareawareofthedifferentwaysofstoppingitThismaybea clutch an onoff switch a No Volts release switch or anemergency stop button I strongly advise fitting a No VoltsreleaseswitchifyourlathedoesnothaveoneAswellasbeingusefulforstoppingthelatheinanemergencyitwillpreventthelathefromstartingupbyitselfafterapowercutIfyouarenotcomfortableworkingwith electrical equipment get a qualifiedelectriciantofittheswitchforyou

StaywiththeLathe

Nevereverwalkawayevenforamomentwhilethelatheyouare using is switched on Switch it off if you are leaving itunattended and only leave the lathe after it has come to a

completestopNeverleavealatheinanunsafeconditionMakesure that you have not left the chuck key in the chuck Thechancesarethatifyouarehalfwaythroughsettingupthelathewhen you return you will forget what you have or have notdoneIfindoubtleaveabignoticeremindingyourselftocheckthatthelatheissafebeforecontinuing

Donotleavethechuckkeyinthechuck

SwitchOffwhenAdjustingtheLathe

Shut off the power supply to the motor before starting anyoperationsrequiringaccesstothelathesuchaschangingtoolsmeasuring work mounting or removing accessories changingspeed and setting up change gears The lathemust be safelystopped Just zeroing a variable-speed drive is not safelystoppingitusethezerovoltsswitchtoswitchthepoweroffaswell

CheckbeforeStartingtheLathe

AlwaysrotateyourworkpiecebyhandtomakesureitclearsthetoolrestsaddleandbedDoublechecktomakesureyourworkis securely clamped in the chuck or between centres beforestartingthelatheBecertainthattheworkpieceturnsfreelyand

isfirmlymountedThespeedofthelathemustbecheckedbeforeturningiton

When turning irregular shapes start the lathe on a low speedandincreasethespeedbyapulleystepeachtimeIfthelatheisbouncingabout lowerthespeedandorbalancethework Ifthe work vibrates stop the lathe and check the reason ThechancesarethatyouarerunningthelathetoofastMeasuringequipment toolingandworkpiecesshouldnotbe

leftona latheastheycanvibrateoff intomovingcomponentsand be thrown around the room Check for loose items on alathebeforeuse

UsetheLatheGuards

NewlatheswillbefittedwithguardsoverthemotorshaftdrivebeltandspindlepulleysTheseguardsshouldalwaysbeinplacebefore using the lathe Any other moving parts should beguardedtopreventanythingfallingontothemovingpartsAlthoughguardsareoften removedbymachinistsprovided

they are constructed from clearmaterials and open and closeeasily theyaddsafetywithout interferingwith theworkbeingdone Guards will at the same time deflect swarf and anycoolantthatisbeingusedGuardsfittedtothelatheshouldnotbe removed while it is in use They should be made fromsuitablematerialandnothavesharpedgesTheyshouldnotberemovedforadjustmentandlubricationofthelatheunlessthisis unavoidable Lathemanufacturers donrsquot usually supply chipguards soaddingoneshouldbeconsideredChipguardswithmagnetic bases are available although they can attract steelswarftothemagnetPutthebaseintoaplasticbagtoaidswarfremoval

UseEyeProtection

Lathes can throw sharp metal chips considerable distancesespecially at high cutting speeds Apart from deep cuts thechipsmay leave the tool red hot cause skin burns and even

burnholes in clothing Youmust use safety goggles or propersafetyspectacleswhileintheworkshopAlwayswearindustrialqualitysafetyglassesfittedwithsideshieldsSpectacleswithoutsafety lenses are not adequate eye protection When theglasses get dirty do not wipe them off as they will becomescratchedWashthemoffunderthetapinstead

TakeCarewhenRemovingSwarf

Do not attempt to remove chips or turnings with your handsAlwaysswitchoff the lathefirstandeitherpull theswarfawaywithalargemetalhookorliftitoffusingapairofglovesIftheswarf is tangled around the lathe untangle it with a pair ofpliersandnotaglovedhandasitwillcutstraightthroughtheglovesandintoyourhandUseadustpanandbrushtoremovesmall chips and swarf from the swarf tray ndash never use yourhandsWhenswarfbecomesstringyandbuildsuponthetoolortoolpostturnoffthelathebeforeremovingit

AvoidLooseClothing

IfyouarenotwearingoverallswearshortsleevedshirtsorrolllongshirtsleevesabovetheelbowsLoosesleevescancatchonrotatingworkandquicklypullyourhandorarmintothe latheObviously though keep your arms protected if hot swarf isflyingaroundSwarf can get inside protective clothing especially collars

(useaclothespegtokeepyourcollartight)pocketsandshoesTostopthesleevesofanoverallcatchingsewelastic intothecuffsorwrapacoupleofthickelasticbandsaroundthecuffstostopthesleevesgettingcaughtupUnder no circumstances wear a necktie when operating a

latheProtectiveglovesshouldneverbewornwhileoperatingalathe Protective gloves may be worn when swarf is beingremovedbuttheymustberemovedbeforeswitchingthelathebackon

UseSturdyFootwear

WearsteeltoecapsafetybootstheyarenotexpensiveandwillhelptoprotectyourfeetfrominjuryifyoudropaheavyobjectonthemThelsquotrainerrsquoversionisparticularlycomfortableDonotallow stringy swarf to fall on the floor as youwill get cuts onyouranklesandmayeventripoverit

AvoidJewellery

Do not wear wristwatches rings or jewellery when in theworkshop as it could catch on a rotating part of the lathe orworkpieceThisalsoapplieswhenmovingalatheintooroutoftheworkshopsincetheycouldcatchona falling lathe IfyourotherhalfcomplainsthatyouhavetakenoffyourweddingringexplainthatyouwouldnrsquotbeabletowearitagainifyourfingerismissingduetoanaccidentLonghairshouldbetiedbackasyoucouldbepulledintothelatheifitgetscaughtintherotatingwork

LiftingintheWorkshop

Back injuries can be caused by incorrect lifting practices It isimportant to bend your legs when lifting rather than bendingyour back A hoist or engine lift should be used to lift heavyitems A stool in theworkshopwill take the pressure off yourlegs and will provide a welcome break after you have beenstoodatthelatheforawhile

Self-ignitingMaterials

If you machine titanium or magnesium which can ignite andburn vigorously keep the accumulation of turnings to aminimum If thematerialdoescatch firedonrsquotusewaterorawater-based coolant as an extinguisher since it will makematters much worse Before starting to machine titanium ormagnesiumfillalargebucketwithdrysandcoveritandkeep

it by the lathe The sand will smother the flames veryeffectivelyYoucouldalsobuyoneofthespecialfireretardantsusedinindustryBeware also of grinding aluminium on the bench grinder

Aluminium and steel filings are the ingredients of Thermite apowerful explosive that can also burn If you grind aluminiumandthenchangeovertogrindingsteeltheredhotsparksareliable to set the steelaluminium mix on fire This is a verydangerous combination ofmaterials and should be avoided atallcosts

SafetywithBarStock

Bar stock should be contained within the headstock and notallowed to protrude from the rear of themandrel I once sawsomeone switchona lathewhenabrassbarwas stickingoutfrom the back of the headstock by about two feet With thelathe running at 2000rpm the bar whichwas aboutfrac34in (19mm) in diameter was bent at right angles and caused theheavy lathe which weighed 1280kg to jump about Luckilysomeone managed to switch the lathe off before any majordamageoccurredItwasnottheoperatorhehadrunwellawayandwasnowheretobeseen

SomeFinalWordsonSafety

Wherever possible the machine height should be adjusted tosuittheuserWearestillusingfifty-year-oldmachinesbutfiftyyearsagothenationwasshorterTheworkplaceshouldbeprovidedwithuniformlightingthat

gives an adequate level of illumination Individual machinelightsarebestThe lathemust be set to operate at the speeds and feeds

recommended for thespecificmetalbeingturned If themetalrotatestooslowlyortooquicklyorthefeed istooslowortoofastaccidentsarelikelytooccurThe area directly in front of and behind the workpiece is

known as the lsquofiring zonersquo or the lsquored zonersquo This is where apiece of work is likely to go as it leaves the lathe Make it ahabit to keep clear of this zone when you turn the lathe onLearnwhere theNoVolts switch is as youmightneed to turnthelatheoffquicklyByfollowingalltheaboveadviceyoushouldnowbeableto

worksafelyfullyawareofanysafetyproblemsthatmightariseAtthispointyounowknowhowtoinstallthelathelookafter

itclean itandmaintain it InChapter3wewill lookatcuttingtoolsandexaminehowtoselectcuttingspeedsandfeeds

Thisbarisstickingouttoofarfromthebackofthelathe

3CuttingToolPrinciplesFeedsandSpeeds

The first part of this chapter will look at the materials fromwhichcuttingtoolsaremadeaswellastheirbasicshapeandgeometryWewill thenconsider selectingsuitablespeedsandfeeds

MAINTYPESOFTURNINGTOOLS

There are three main types of turning tool used in modernworkshops HSS (high speed steel) tools carbide brazed-ontoolsandinsertedtiptoolsAllhavetheirusesintheworkshopandformost jobsthere isnopreferenceforonetypeovertheothersTherearealsocarbonsteeltoolbitsalthoughinpracticetheyarejustaboutobsoleteCarbonsteeltoolscanbemadeinthe homeworkshop but apart frombeing used tomake formtools(seeChapter11)thereaderisunlikelytousethismaterialfortools

Ageneral-purposeHSSturningtoolsuitableformildsteel

HSSTOOLS

HSStoolscanbepurchasedsinglyorinsetsalreadygroundtothecorrectshapeIt ischeaperhowevertopurchasethemassquare tool blanks in various sizes ready for you to grind toshapeThecompleteready-groundsetswillprobablycomewithseveralshapesincludedthatyouwillneveruseIfyoucanbuyafewready-groundtoolscheaplytheywillbeofuseasguidestoseehowtosharpenyourownHSStoolblanksHSS form tools from industry are often available second-

handTheseareespeciallygroundtomachineacomplex formall in one go You can often find some that are ground to asuitable shape to form the end of a threaded componentincludingtheundercut

HSSformturningtools

Brazed-onCarbideTools

Brazed-on carbide-tipped tools are quite useful especially forfacing and boring cast iron but they really need a diamond-facedgrindingwheeltokeepthemsharpCarbidetipsandtoolscomeinvarioussizesandhardnesstosuitindividualmaterialscarbidetoolsforsteelwilloftenbepaintedbluethoseforcastiron are painted red and those for stainless steel are paintedyellowThecolourindicatesthesuitabilityofthetoolforcertainmaterials

Brazed-oncarbide-tippedtoolscomeinvariousgradesshapesandsizes

InsertedTipTools

InsertedcarbidetiptoolsareveryusefulbuttheyarenotcheapThe tipsarenotusually sharpenedafterwearingout you justthrow the tip away and fit a new one Most modern carbide

inserts however do have more than one cutting facesometimestheyhavetwoandoccasionallyfourormorecuttingedgesareavailableYoucanevengetformturningtoolswheretheinsertisroundandcanberotatedafull360degrees

Theleft-handtoolisblueindicatingitisformildsteelwhiletheright-handtoolisredindicatingitisforturningcastiron

Some diamond-shaped tips can be used in different toolholders two edges are used in one tool holder and the othertwoedgesareusedinanothertoolholdersoyougettwicethelifepertipInserted tip tools are available for internal and external

screwcuttingwherethetipsareheldat thecorrecthelixangleofthethreadinthetoolholderThedrawbackisthecostofthetipsandeachsizeofthreadusuallyneedsitsownsizeoftip

Aninsertedtipcarbideturningtool

Carbidegroovingtools

InsertedtipgroovingtoolsareidealformachininggroovesforOrings and circlips Theyare available inmany standardwidthsandcanoftenbeusedasparting-offtoolsforsmallerdiametersOneof themostusefulgrooving tools forsmallersizegroovesandpartingoffistheMiniThinsystemassoldbyMSCIndustrialSupplyCo

TheMiniThintoolholderisidealforgroovingandalsoforpartingoffsmalldiametersTheshankissostrongcomparedwiththecutbeingtakenthatusinganoverhangasshownisquite

safe

Coatingstoreducetoolwear

Tipsarealsoavailablewith various coatings that improve toollifeThemostcommoncoatingistitaniumnitride(TiN)whichisgold in colour Other coatings that offer slightly better wearresistancearetitaniumcarbonnitride(TiCN)whichisbluegreyincolourandtitaniumaluminiumnitride(TiAlN)whichisvioletbronzeReady-groundHSScuttingtoolssuchasdrillstapsandreamers are also available with these coatings but once yousharpenthecutterthecoatingisgoneTipped toolsneedadeeper cut ahigher feedandahigher

speed than HSS tools Thismeans that the lathe needs to bestrongrigidandhaveamplepowertodrivethe lathemandrelwhen taking a heavy cut this rules out using tipped tools onlathessmallerthanabout2in(50mm)centreheightSmaller tools are made to fit the Unimat and similar small

lathesbutthesemachinesjustdonrsquothavethepowerneededtodrivethemAtbesttakingacutwillstopthelatheatworstthetoolwillchip

Insertedtiptypes

Inserted tip tools come in many shapes and sizes Some tipshapes and sizes are made to an international standard andothers are to the makerrsquos own standards Wherever possibleuse ISOstandardtoolsas thetipswillbe interchangeablewiththosefromothermanufacturersandwillprobablybecheaperaswell The ANSI system commonly used in the USA is notcompatiblewiththeISOsystemusedintherestoftheworldIfyour lathe ispowerfulenoughyoucantakeadvantageof

insertedtippartingoffbladesThesearemounted inaspecialtoolblockandthebladecanbeslidinoroutdependingonthediameteryouarepartingoffThebladecarriesan inserted tipspecially designed for parting off There are three types of tipavailablesquare-endedtipstipsthatareangledtotheleftand

tips that are angled to the right Square tips are used forgeneral parting off tips angled to the left are usedwhen youdonrsquotwanttoleaveapiponthebackendoftheworkandtipsangledtotherightareusedwhenyouwantacleanfaceonthefrontoftheworkThe parting off blade is oftenmounted upside down at the

backofthe lathecrossslideTheactionofpartingofftendstolift the whole cross slide slightly and forces the cross slidetightly into thematching dovetail whichmakes itmuchmorerigidIfthepartingofftooldigsinwhileinthebacktoolpostthetool tends to lift and push away from the work whereas in afronttoolpostthetooltendstodiginandpullintothework

Simplifieddiagramofpartingofftoolangles(A)straightpartingtool(B)angledtotheleft(C)angledtotheright

POWERREQUIREMENTS

Whenturningmildsteelorstainlesssteelwithanycarbidetoolthe machine horse power required is considerably more thanthat required forordinaryHSStoolsThe twomain reasons forthisarethatcarbidetoolsoftenhaveanegativerakeangleonthecuttingedgeasthistypeofedgelastsmuchlongerthanapositiveangle especially for intermittent cuts andbecause in

industrial use carbide tips are called on to remove largerquantitiesofmetalathigherspeedsandfeedsFor guidance on using tipped tools in the small workshop

wheretimeisnotasimportantasinanindustrialenvironmentIwould recommendusing twice the speedused fornormalHSStools and a fine feed of about 0002in (005mm) per rev as astarting point This can be adjusted up or downdepending ontheresultsThemaindifferencebetweenHSStoolsandcarbidetippedtools(eitherbrazed-onorinsertedtip)isthehorsepowerrequirementofthemachineinuse

Thispartingofftoolismountedatthebackofthelatheinaspecialbacktoolholder

SELECTINGTHECORRECTSPEEDSFORDIFFERENTMATERIALS

Overmanyyears through trialanderror cuttingspeedshavebeendeterminedthatgiveanoptimumtoollifebalancedwithadecent surface finish These speeds are normally quoted inlsquosurfacespeedinfeetperminutersquoSpeeds and feeds used on industrial machines where the

primary tools will have inserted tips will be a lot higher than

thoseusedinthesmallworkshopwhereHSStoolsarethenormThe accompanying table gives an idea of the speeds that

shouldbeused forvariouscommon typesofmaterial likely tobefoundintheworkshopThespeedslistedshouldbesuitableforbothturninganddrillinginthelatheForreaminguseabout25percentoftherecommendedspeedsThe table is a guide only and it is likely that the machine

speedsavailablewillnotbeexactlythoserequiredandyoumayhavetoresorttolsquonearenoughisgoodenoughrsquoSetthelathetothe nearest speed lower than indicated in the table for thediameterandmaterialbeingcutThiswillbefineforHSStoolsDouble the recommended HSS speed for carbide tools For

parting off use about 30 per cent of the recommended HSSspeed For form tools use about 50 per cent of therecommended speed for the initial cuts and then engage thecorresponding back gear (just switch to back gear leaving thebelts on the same pulley) and gently tap the handle until itreachesthefinishedsizeandallowittofinishthecutbyitselfYou may have to adjust the speed down if you get a lot ofchatter

Forturningcastironuseacarbide-tippedtoolrunningattheHSSspeedtoremovetheskinYoucanthenfinishtheturningwithaHSSsteeltoolifyouwishPlease remember if doing any work that might be

unbalancedstartoffslowlyandincreasethespeedabeltstepatatime

THEACTIONOFCUTTINGTOOLS

Basicallya lathe tool isawedge that is forced into theendofthe rotating bar to remove metal As long as the tool is fedforwardwhilethelatheisrotatingmaterialwillberemovedA typical right-hand turning tool has a cutting angle of 90

degreeslessthesideclearancelessthesiderakeThecuttingangle for this example is 90ndash10ndash10= 70 degrees This is theangle that is wedged into the work to remove the materialSoftermaterialswillhaveasmallercuttinganglewhilehardermaterials will have a larger cutting angle Tool angles varydependingonthetypeofmetalbeingturnedToolsforturningsofter metals usually have higher rake angles than thosedesigned for harder metals since a turning tool will normallyholditsedgeforlongerinsoftermaterialsBrassalthoughsoftusuallyhasnotoprakeonthetoolatallOther angles to be aware of are the top rake and the side

rake

CUTTINGTOOLSHAPES

The followingaresomeof thedifferent shapes thatyoumightfindusefulforgeneralturningandmetalremoval

Right-handknifeturningtoolAllrakeanglesare10degrees

Right-hand knife tool This is used for general turning andfacingofbarstockDependingontheworkyouaredoingyoumayfindaleft-handversionofthistooluseful

Typicalroughingtool

Right-handroughingtoolIthasaleadingangleandasmallradius on the tip of the tool This tool is used for fast metalremovalwherefinishisnottooimportantAgainyoumayfindaleft-handversionusefulAroughingtoolcuttingatanangletoabarwillremoveachip

widerandthinnerthanatoolcuttingat90degreestothebarThis improves tool life although you will have to square theturningupwithastandardknifetool

Typicaldouble-sidedroughingtool

Double-sided roughing tool It can turn towards the left orright It canalsobeusedasaplunge tool to removematerialfroma groove orwhere the component needs to be lsquowaistedrsquodown

Simplepartingofftool

Simple parting off tool This is suitable formostmaterialsYouwillprobablyneedalargeoneforpartingofflargediameterbarsaswellasasmalloneforpartingoffsmallcomponents

Internal(top)andexternal(bottom)screwcuttingtools

ScrewcuttingtoolThisisusedforcuttingscrewthreadsTheanglewilldependonthethreadyouarecutting60degreesformetric55degreesforWhitworthandBSFetc

Shallowboringtoolcapableoffacingacrossthebottomofahole

Boring and facing tool This toolrsquos unusual shape will befound very useful when recessing a large bore It will plungestraight intoasmalldrilledholeandwillalso face rightacrossthebottomoftherecess

Double-endedchamfertoolchamferingadiameter

Double-ended chamfering tool It has 45 degree angles atbothendssoitcanbeusedtochamferexternaldiametersandinternalbores

Double-endedchamfertoolchamferingabore

Othershapescanbeusefulbutthetoolsshownhereshouldbesufficienttogetyougoing

BORINGTOOLS

Boring tools are used to clean up a previously drilled holepossiblytomakeitruntruebutmorelikelytoensuretheholeistothecorrectsizeTheyarenormallylongerthanordinarytoolsandtendtostickoutfurtherfromthetoolholderHSStoolsaresuitableformostusesCarbideinsertedtipboringbarsarealsoreadilyavailableandarethebestbetforturningcastironinthesmallworkshop

HSSboringbar

For really small holes down to2or3mm indiameter solidHSSandcarbideboringbarsarereadilyavailableAlthoughtheyarenotcheaptheywillbefoundveryusefulandquicktouseAnothermethodofboringahole is tousea longseriesslot

drillasaboringtoolInuseclamptheshankinthetoolholderwiththepointatcentreheightmakingsuretherestoftheslotdrillisclearofthesideoftheboreYoucanthenrunitthroughtheboreinasimilarmannertoastandardboringbar

Asmallcarbideboringbarinsertedintoamildsteelshank

PARTINGOFFTOOLS

PartingofftoolsprovideaquickwayofcuttingoffworkfromtheparentbarThereisrarelyanyneedtoworryaboutcuttingthecomponentofftothecorrectlengthtogetagoodfinishAslongasthecomponentislongerthanrequireditcanbeputbackintothe chuck or a collet and the parted off face can be faced tolengthorotherwiseworkedonThepartingofftoolcuttingfacecaneitherbesquareoritcan

beangledtotheleftorright(seepage43)Thesideofthepartingofftoolcouldevenberadiusedsothat

it forms a radius on the end of the next component orchamferedtoformalead-inedgeforthenexttool

CUTTINGLUBRICANTS

Tomake cutting tools cut easily and to prolong their life it issometimesbesttouseacuttinglubricantForsteelIpreferneatcuttingoilItlubricatesbutisnotidealforcoolingtheworkIn industry coolant is normally used This is oil that has an

additivetomakeitsolubleinwaterMostsolubleoilswilldobutthe synthetic ones tend to sting your hands if you have anyopen cuts I would not recommend using soluble oils on thehome workshop lathe as I think they tend to wash thelubricating oil off the slideways and can encourage rustHowever this ismypersonalpreferenceandmanypeopleusesolubleoilinthehomeworkshopwithoutanyproblemsOil is suitable for use when cutting steels mild steels

stainlesssteelsandhighcarbonsteelssuchassilversteelThebestlubricantwhencuttingaluminiumisparaffinItstops

thealuminiumfrombuildinguponthecuttingtoolBrassandcast ironarenormallycutdryWhenturningcast

ironona lathe if the latheisfittedwithasolubleoiltankthecastirondustwillhaveanaffinityforthesolubleoilIfthelatheisthenusedonaluminiumthefreecarboninthecast ironcancontaminatethealuminiumwithblackstreaks

Inormallyplacetheoilorparaffininasmalldish(actuallyacatordogfoodbowl)andapply itbyhandwithasmallbrushThisdoesallIneedThenextchapterlooksatgrindinglathetools

4SharpeningToolsandHoldingThemintheLathe

ThenexttaskistogrindasetofusefullathetoolsThe first thing you will need is an off-hand grinder The

grindercanbeadangerousmachineso itshouldbeusedwithcare Eye protection must be worn the guards should becorrectlyfittedandtheremustbeadequateilluminationIdonrsquotlike using a grinder in a small workshop as the grinding dustflies everywhere and canget onto themachine slideways andtools generally making the workshop dusty and dirty Ifpossible set up thegrinder in a separate areaaway from theworkshopIhavemygrindermountedonafoodchoppingboardso I can carry it outside to use This has the addedbenefit ofdaylight although you are dependent on the weather or youmightneedtouseitafterdark

Theguardofthisoff-handgrinderhasbeenwidenedtoacceptarecessedwheel

GRINDINGWHEELS

IthasalwaysbeenstatedthatyoushouldnevergrindatoolonthesideofthegrindingwheelSofollowingthistheorywewillbeusingarecessedwheelwhereitswidthismuchthickerthanthepartofthewheelusedtoclampthewheeltothegrinderIstruggledtofindarecessedwheelof6in(150mm)diameterandfinally found a 60 grit grinding wheel on a personal visit toAxminster Power Tools in Devon (I could find only an 80 gritwheel in theircatalogue)Thewheels I like touse forgrindingare A60K5V if I can get them and I prefer the white wheelsdesigned for the harder tool steels rather than the grey orbrown wheels which are more suitable for softer mild steelsThedesignationbreaksdown like thisA stands foraluminiumoxide 60 is the grit size K is the hardness (I J and K beingmediumhard)5 is thestructure(thespacebetweengrainsofgrit) and V is for vitrified the method of bonding the grainstogetherTheKandthe5canvaryabiteitherwayandthegrit

shouldbe4660or80with60beingpreferredThe80gritisabitfineandwillclogupquitequicklySo-called green grit wheels made from silicon carbide are

available for sharpening carbide tools They are usually softerthanaluminiumoxidewheelsinordertoallowthegrittobreakdownbeforethewheelbecomesglazedfromgrindingthemuchhardercarbide

Witharecessedwheelyoucancutontheouterfaceoftherecessedsideofthewheel

TestingtheWheel

The first thingyoushoulddowhenbuyingawheel is tomakesurethat it is ratedatasufficientlyhighspeedfor thegrinderon which it is to be used Off-hand grinders usually run ataround2900rpmsoyouwillneedawheelratedtoatleastthatspeed it is all the better if the grinding wheel is rated at ahigher speed than the grinder Care should be taken whenhandlinggrindingwheelsastheyarequitefragileifknockedordropped A grinding wheel should only be purchased from areputableengineeringsupplierSupportyourgrindingwheelona piece of wood and tap the wheel gently with a plasticscrewdriver handle or similar The wheel should lsquoringrsquo if itsoundsdullitshouldbebrokeninhalfandeitherthrownawayorusedontheworkbenchasasharpeningstoneNeverthrowawheelawaywithoutbreaking it into twoyouneverknowwho

mightgettheirhandsonit

Thistoolrestwasdesignedtosharpenplaneironsandchiselsbutitisfineforlathetools

Amoderndigitalanglegaugeisidealforsettingthetoolrest

MountingtheWheel

The wheelrsquos bore should be the same as the spindle of thegrindingwheelOften theborewillbe largerandyouwill then

need some plastic spacers to reduce it Spacers should bereadilyavailable fromyour localengineeringsupplierYoucanturn thespacers fromplastic if youcanrsquotbuyany ready-madeonesAt each side of the wheel you should fit a paper washer

thesearemadeofblottingpapertypematerialandwillprobablyhave been supplied already stuck on the wheel The grindershould have twometal flanges one to fit at each side of thewheel Both flanges should be the same diameter These willhold the wheel true and spread the tightening load on thewheelThegrinderwillhavetwodifferent threadsontheendsof its spindle The right-hand side of the grinder will have aright-hand thread and the left-hand side will have a left-handthreadThedifferentthreadsaretostoptheclampingnutsfromunscrewingwhenthegrinderisrunningTofitthewheelremovetheguardandundothenutRemove

the metal flange and then the wheel Make sure the flangesdonrsquothaveany remainsof theoldpaperwasheron themPutthenewwheelontothegrinderspindle(rememberthespacerthepaperwashersandtheflangesateitherside)andscrewthenuthand-tightFinallyholdthewheelgentlyandgivethenutapinchupwithaspannerYoudonrsquotneedtoover-tightenthenutjustsufficiently tostop thewheel fromcoming looseRefit theguard and spin thewheel by hand to ensure it is not rubbinganywhereNowwearealmost ready to switch thegrinder onBeforedoingsohoweverputonyoureyeprotectionandstandtoonesideofthegrindersoyouarenotinlinewiththewheelshould it burst Then switch the grinder on All should be fineandthewheelshouldberotatingsafely

TOOLREST

Theworkrestsuppliedwithanoff-handgrinderisusuallyjustabitofbentsheetmetalboltedonItisusablebutonlyjustI recently purchased a ready-made tool rest as a basis for

makinganimprovedgrindingrestThiswasoriginallydesigned

forsharpeningplanebladesandchiselsforwoodworkingbutitmakes an ideal rest for sharpening lathe tools It is made ofaluminiumandisfullyadjustableforangleThebestmethodofsetting the rest to the correct angle is to use a digital anglegauge These are now very cheap and are readily obtainableThepositionoftherestinrelationtothegrindingwheelcanbeadjusted on its sliding base Many designs for tool rests havebeenpublishedandyoucouldmakeoneofthoseinsteadifyouwishtosavemoneyThetoolclampassupplied isdesignedtoclampplane irons

andchiselssothisneedstobechangedLathetoolsneedtobepresented to the grinding wheel at the correct angles If youdonrsquot have a digital angle gauge this can be achieved usingsimpleguidesmadefromanglesheetmetalandsomescrewsIused gauge plate made from a high carbon steel with anaccurategroundfinishthatcanbehardenedandtemperedbutmild steel would be perfectly suitable if you donrsquot have anygaugeplateavailableYouwillfindaprotractorusefulyoucangetasteelonewith

an adjustable blade for a reasonable price The protractorwillbeusedtosetthetoolanglethatisgroundonthetools

Sheetmetalprotractorsareavailableverycheaply

LATHETOOLGEOMETRY

LathetoolsneedtobegroundtocertainanglesbuttheanglesdonrsquothavetobeexactFormosttoolssomewherehandywilldounless you are grinding a form tool to a particularly accurateshapeIthasbeennormalforbookstoshowtheanglesontoolsas used in a production environment where tools will ideallyhavealonglifeoftenthislifeiscalculatedaslastinganeight-hourshiftsothetoolonlyhastobesharpenedandresetonceadayInthehomeworkshopwecan increasethesecuttingangles

andgetbettercuttingattheslightexpenseofshortertoollifeWehavealreadyexplainedtheshapesof the tools thatyou

willfindmostusefulToolanglesareknownbytechnicaltermstop rake front rakeside rakeandback rakeThe rakeanglesvary depending on thematerial to bemachined but a set ofstandardtoolswillgetyoustartedSomeoftheaccompanyingphotographsareactuallyoflarge-scalewoodenmodels

Theleft-handtoolissuitableforbothfacingandturningtheright-handtoolissuitableforturningonly

Left-handsideofthefacingandturningtoolshowingthefrontandtoprake

Topofthefacingandturningtoolshowingthefrontandsiderelief

Left-handsideoftheturningtoolshowingthefrontclearanceandthetoprake

Topoftheturningtoolshowingthefrontandsideclearanceandthetoprake

GRINDINGATOOL

WhengrindingHSStoolstrytokeepthemascoolaspossibleIfan HSS tool becomes too hot and is then quenched in waterminutecrackswillformonthecuttingedgesThesecrackswillmakethetoolcuttingedgebreakdownveryquicklywhenusedThe best practice is to grind a little bit off the tool and thenquenchitwhileslightlywarmDonotletthetoolgethotdipitin thewater little andoften This should ensure the tool edgedoesnotbreakdowninuse

GrindingYourFirstTool

Most angles can be ground by using the tilting table whileothersmayneedtobefixedinrelationtotheperipheryofthegrindingwheelThefrontandsideofthetoolcanbegroundbytippingthetableatthecorrectanglewhereasthetoprakecanbegroundontheperipheryofthewheelThegrinder should first be switchedoff andunplugged Set

thetoolresttotherequiredangleusingthedigitalanglegaugeoranangletemplateandtightenuptherestBefore switching on the grinder ensure that everything is

freetorotatebyspinningthegrindingwheelbyhandIf all is well put on your safety glasses and switch on the

grinderPlacethetoolonthetoolrestupagainstthesideoftheprotractor Slide the tool along the table until it reaches thegrindingwheel andmetal starts to be removed Slide the toolbackwards and forwards slowly along the restwhile putting alittle light pressure on the tool so that it continues to pressagainst the grinding wheel When you have removed a smallamountofmaterialcoolthetoolbitdownAtnotimeallowthetool bit to get hot Continue grinding until you have removedsufficientmaterialfromthetoolbit

Thegrindingrestissettothecorrectangleof10degreestogrindtheendofthetool

Grindingthefirstangle

TurnthetooltotheotherangleanddothesamesothatnowboththefrontandsideclearanceangleshavebeengroundThis toolwill be enough for brass but for steelwe need to

grindthetoprakeWhengrindingthetoprakeonaright-handtool the slide rest needs to be higher than the centre of thegrinding wheel so that it grinds the tool at approximately 10degrees

Thefirstanglehasbeenground

You have now ground your first lathe tool The tool asreceivedfromthegrinderwillbetooroughtousehoweversoyouwillneedtohonethecuttingedgesYoucandothisonanoilstone(usedwithfineoillike3in1)orwithadiamondlaporusing a combination of the two Lightly lap the front and sideclearanceanglesuntilyougetagoodfinishand lightlyhoneaverysmallradiusonthetipofthetoolFinallyhonethetoprakeangleandyourtoolisreadyforuse

Grindingthesecondangle

Thesecondanglehasbeenground

AllofyourHSSturningtoolscanbedoneinthiswayOnlytheangleswillvaryandthesecanbesetusingadigitalanglegaugeandprotractorAnoccasionalhonewillresharpenyourtoolsaslongasyoutreatthemwithcareA similar range of HSS tools and a parting off tool all with

zero top rake shouldbeavailable if youwill be turningbrassUnless you are doing quantity production one tool holdershouldbesufficientforbrassAsatoolforbrasshasnotoprakeandyouwouldnotnormallygrindthetopawayaslongasyoubuy tool steel of the same size the tip height will remain thesameYoucanthenusethedifferenttoolsinoneholderwithouthavingtoresettheheight

MACHININGCASTIRON

Carbide-tippedtoolsareidealformachiningcastironAsimplebrazedupcrankedtoolwithasmallchamferonthenosewilldoforbothturningandfacingcastironcomponentsThemainuseof this tool will however probably be truing up the faceplatethat comes with the lathe The large diameter combined withtheintermittentcutovertheboltgrooveswoulddestroyanHSStoolinafewsecondsAsmalltippedboringbarwillbeidealfor

taskslikeboringcastironcylinders

Grindingthethirdangle

Asimplediamondlap

Thethirdanglehasbeenground

Tosharpentippedtoolsyouneedadiamondwheelorifyouwant to remove large amounts of carbide a silicon carbidewheeloftencalledagreengritwheelowingtoitsusualcolourSilicon carbide wheels are much softer than aluminium oxidewheels as they need to break down faster to present newsharpergrainstothecarbidetoolAdiamondwheelisonlydesignedtolightlylapatippedtool

itisnotsuitableforremovinglargeamountsofcarbide

Diamondcupwheel

TOOLHOLDING

Smallerlathessuchasarefoundinmostworkshopsmayhaveatopslidewithatoolclampforindividualtoolsablockwithasingle slot to take the tool a four-way turret (or sometimes athree-way)oraquick-changetoolblockandholdersetThereisalsotheso-calledAmericantoolpostwhichisaroundbarwitha slot through it and a bolt in the top to clamp the tool ItusuallycomeswithmatchingdishedwasherstoadjustthetoolheightThistypeisnolongerverycommononlathes

Quick-changeToolPost

Themostversatiletoolholdingsystemisthequick-changetoolblockwithmatchingholdersThedrawbackwiththissystemisthe cost of extra tool holders you need quite a few one foreachtoolThequick-changetoolblockmountsonthefrontofthelathe

normallyontopofthetopslide(Blockscanbefitteddirectlyon

thecrossslidebytheuseofaraisingblocktoaidrigidity)

Quick-changetoolblock

Each holder is set up with its own particular tool The toolholderscanbe individuallysetso that the turning tool isdeadoncentreheightandispresentedcorrectlytotheworkpiece

Quick-changetoolholder

Quick-change tool holders are available with a straight cutslottotakestandardsquareshanktoolholderswithastraightcutwiththeadditionofaVeecut-outinthebottomforusewithroundtoolssuchasboringbarsandasafrontpartingoff tool

holdertotakeahighspeedsteelpartingoffbladeRearpartingoff tool holders are available to take an inverted parting offbladeeitherahighspeedsteelbladeoran insertedtipbladeLeft-handed and right-handed extended tool holders are alsoavailableandmayoccasionallybequiteusefulThetoolblock isnormallymountedonthetopslidebutyou

cangetraisingblockstouseinsteadofthetopslideThismakesthetoolholderblockmuchmorerigidAbackquick-changetoolblockwillneedmountingonaraisingblock

Backofaquick-changetoolholdershowingthedovetailtypeofmounting

Right-handandleft-handextendedtoolholders

StandardtoolholderwithaVeetotakeroundtoolholders

Frontpartingofftoolholder

ToolClamp

Satisfactoryworkcanbedonewithatoolclampedontothetopslideusingshimsteel toset thecentreheightof the toolThemaindrawbacksarethatyoulosethepositionofthetoolwhenyoutakeitoffthetopslidetofitthenexttoolandyoualsolosetheaccuratecentreheightofthetoolunlessyoukeepthetoolandshimstogetherIfyouaremakingonlyonecomponentthisisnotaproblembutitisanuisanceifyouaremakingabatchofmatchingcomponents

Simpletoolclamp

Single-slotBlockToolPost

AblocktoolpostisoftensuppliedwiththecheaperlathesThetoolpostisliterallyablockofmetalwithaslotcutinittotakethe turning tool It is relatively easy to set the tool up at thecorrectcentreheightbyusingvariousthicknessesofshimThisisfineforthebeginnertoturningwhoisjuststartingoutbutitisbesttoreplaceitwithafour-waytoolpostoraquick-changetool post You could of coursemake several block tool postsandkeepeachonesetwithadifferenttool

Four-waytoolpost

Backtoolpost

Four-wayToolPost

Four-wayToolPost

Thefour-waytoolpost isagoodcompromiseona latheasyoucansetfourtoolsintheturretandrotateeachoneintopositionas needed This speeds up production and is a lot faster thanusingasimpletoolclampThedrawback isthatthetoolsstickoutof the turret fourdifferentwaysandyoumightcatchyourhandonasharp toolAsimple ratchetstopensures thateachtool repeats its position when the tool post is rotated so theworkisaccuratelyturnedeachtimethetoolisusedAduplicatefour-waytoolpostwithtoolsforbrasswillspeedupproductionevenmoreCastingsareavailabletomakeyourownthree-waytoolpost The three-way toolposthas theadvantageofbeingable to get close to the work when you are turning betweencentresFor the front tool post I would recommend right-hand and

left-hand roughing tools right-hand and left-hand finishingtools a tool groundup to face barswhile using a half centreand a Mini Thin inserted tip grooving tool with grooving andparting off inserts You will also need large and small boringbarsbothHSSandwithinsertedtipsTheHSStoolsshouldbegroundupforuseasgeneral-purposeturningtoolsformildsteelandsimilarmaterialsThecarbideinsertedtipboringbarshouldbefineforcastiron

BackToolPost

You can fit a quick-change tool block to theback of the crossslideaswellasthefrontSpecialholdersareavailabletotakeaHSSparting off blade or an inserted tip parting off blade Thebladewill be angleddown to give top clearancewhenpartingoffTheseback-mountedtoolblocksareveryhandyastheycanalsobefittedintotoolholderswithafacingtoolorachamferingtoolFor a back tool holder set-up I would recommend an HSS

partingoffbladeafacingtoolforcastironandadouble-ended45-degree chamfering tool that can be mounted parallel with

the chuck or at 90 degrees to it This set-upwill allow you tofaceaworkpiecechamfertheoutsidediameterandortheboreandpartitofftolengthThenextchapterlooksatholdingworkinachuck

5WorkholdingintheChuck

This chapter covers the different types of chucks how to usethemandsetupworkinthemaccurately

Aself-centringthree-jawchuckfittedwithlsquodrilljawsrsquoNotetheexternaljawswhichareinterchangeablewiththedrilljaws

USINGCHUCKS

Themostusefultoolsforworkholdinginthelathearethree-andfour-jaw chucks The three-jaw chuck is usually of the self-centringvarietythistypeofchuckcomesasstandardwithtwosets of jaws The first set of jaws are known as inside or drilljaws as they are most useful for holding round and hexagonbarsTheother setof jawsareoutside jawswhichholdworkusuallyindiscformontheoutsideSelf-centringmeansthatwhenyouinsertabitofbarintothe

chuck and turn the chuck key the chuck centralizes theworkpieceas it tightensup It isunlikely to runperfectly truebutitshouldruntruewithin3or4thouYou can also purchase soft jawswhich are exactly as their

namesuggestsYoucan thenbore themout to fit thework Ifyouborethemonthelatheyouaregoingtousethemontheworkwillrundeadtrue

Asetofsoftjawscanbeturnedorboredtosuittheworktobeheld

Aself-centringfour-jawchuckThesealsocomewithexternaljawsandsoftjawsareusuallyavailable

Self-centring four-jaw chucks can be used for square barsTheyarealsousefulforholdingroundbarswithmoregripthanathree-jawself-centringchuckSoft jawsarealsoavailableforfour-jawself-centringchucks

Afour-jawindependentchuck

Youare howevermuchmore likely to comeacross a four-jaw independent chuck than a four-jaw self-centring chuckIndependent means that the jaws can be moved individuallyand the jaws can also be reversed one two three or four ofthemdependingontheworktobedone

Abaseplatecastinginafour-jawindependentchuck

Wewillfirstlookatthethree-jawchuckThebestmethodofmaking a component in one of these is if possible to turn itcompletely at one set-up If you put a piece of bar into thechuck face the end centre drill drill and ream it skim thediameterandpartitoffitshouldbeconcentricalloverThisisbecausewehaveturneditallatthesamesettingwithouttakingit out of the chuck If we need to machine the other endhoweverwhenwe turn it roundandput it back in the chuckthechancesareitwillnotruntrueThis iswherethe four-jaw independentchuckcomes inYou

canput thecomponent intoa four-jawchuckandset it to runtrueusingthedialtestindicatorAnyworkyoudoonthepartedoff end should then be concentric with the rest of thecomponentWhensettingworkinafour-jawindependentchuckfor a second operation use some thin shimbetween the jawsandtheworkpiecetoavoidmarkingtheworkWorkisoftenheldinafour-jawchuckbecauseitisacasting

anoddshapeorsquareandsowonrsquotfitintoathree-jawchuckIf thework just requires tobe faced flat rightacross the facethereisnoneedtosettheworkrunningradiallytrueItshouldbe near enough on the centre line as long as the work is

reasonablybalancedYou could of course put the component into a three-jaw

chuckbyfittingsoft jawsandmachiningorboringthemouttotake the component This is the best option ifmaking severalcomponentsthatneedtobeidenticalbutifyouonlyneedoneor two components a four-jaw independent chuck will be thequickestmethodofmachiningthemLargerdiameterscanbeheld ina three-jawchuckbyusing

theoutsidejawsThesehavealargeradiusontheinsideofthejaw ifthisradiusis largerthantheworkpiecethejawsshouldnot tend to dig into the work and mark it Outside jaws areuseful forholding components like small flywheels locomotivewheels and chuck backplates when machining the bores ofholesorwhenmachiningacrossthefaceWhenmachining thindiscs it isuseful toputsomepacking

behindthedisctomakeitstandproudofthejawsTostopthepackingflyingoutwhenthemachineisrunningmakeasetofthree or four packing pieceswith grooves at each end and fittensionspringstothemTheyshouldallbethesamediametersothatthebackoftheworkisparalleltothechuckThelengthand grooves can vary slightly as they donrsquot affect theparallelismTheyarequickandsimpletomakesoacoupleofsets of different diameters should find their way intoeverybodyrsquostoolbox

AlthoughmostlathechuckkeyshavesquareendstheyareoftenofdifferentsizesKeepeachkeywithitsownchuck

ChuckKeys

I have alreadymentioned that the chuck key should never beleftinthechuckwhenitisunattended(seeChapter2)PutthekeyintothechuckuseitandputitsafelyawayassoonasyouhavefinishedwithitIfyouswitchonthelathewiththekeystillinthechuckyoumightneedatriptothehospitalDonotuseexcessive forcewhenyou tightenup the chuck

Do not use a piece of tube a spanner or anything else as alever thechuckkeyon itsownshouldbesufficient to tightenthechuckontotheworkWhenusinga four-jawchuckasmallchuckkey littlemore

thanaknurledknobwithasquareoncanbeusedtoadjustthejawsinandoutpriortotighteningupwiththeproperchuckkeyThiswill save timeover adjusting the jawswith a large chuckkeyTo turn the independent four-jaw chuck jaws round a

carpenterrsquosbracewithapieceofsquarebarinittofitthechuckwillmakeshortworkofreversingthe jawsbutdonrsquotuse it forthefinaltighteningasitisliabletostrainthejaws

STARTINGTOTURN

Before going any further you need to learn how to do basicturningFor thisyouneed toput the three-jawchuckonto themandrelStartbycleaningthemandrelwithacleanbitofragorsimilar(Ikeeparollofpaperkitchentowellingintheworkshop)Nowyouneed toclean thechuckrsquosboreand threadusing thetwotoothbrushmethod(seeChapter2)BoththemandrelandthechuckshouldbecleanbeforeyouattempttofitthechucktothelatheSelecting and grinding turning tools has already been

discussed (see Chapter 4) so by now you should have acorrectlygroundturningtoolsuitableforroughingoutapieceofsteelbar

Barwithapiptoolaboveorbelowcentreheight

MakingaToolCentreHeightSettingGauge

Thistoolneeds itscuttingedgesettothecentreheightofthelatheThereareseveralwaystodothisbutoneoftheeasiestiswith a home-made height gaugeWhen starting out this is achickenandeggsituationyouneedtomakethegaugetosettheheightbutyoualsoneedatoolsetatthecorrectheighttomakethegaugeThesimplestwaytoovercomethisproblemistosetthelathe

tooltotheapproximatecentreheightandtakeacutacrossthefaceofthebarDependingonwhetherthereisapipremainingon theendof thebaryoushouldgetan ideahow farout thetoolheightisIfthereisnopipthismeansthetoolisoncorrectcentre height or too high A pipmeans the tool is too lowOfcourse you may have been lucky so try dropping the toolslightly until a pip remains You can then raise the tool a fewthouatatimeuntilthepipdisappearsThetoolshouldthenbeoncentreheight

Barwithnopiptooloncentre

Nowthatthetoolisatcentreheightyoucanmakeasimpleheight gauge Turn a piece of bar down to as close to frac12in(12mm)asyoucangetandleaveitinthelathechuckMeasurefromthetopofthecrossslidetothetopofthebarwithacheapheightgaugeLowertheheightgaugebyhalfthebardiameterTheheight

gaugeshouldbeexactlyonthelathecentrelineMakeanoteofthisdimensionWe now need to look at how to turn a bit of bar to an

accuratediameterWhenturningabartosayfrac12in(12mm)youneedtostartwithsomethingslightlylargerInthiscasethiswillbe⅝in(16mm)diametermaterialasthisisastandardsizeCutapieceofmaterialabout2in(50mm)longandputitinto

thechuckwithabout1in(25mm)stickingoutSkimtheoutsidedown to about 0510 thou or 1225mm which is 10 thou(025mm) above the size required (You should be aware thatmosthobbylathedialsremovetwicewhattheysayaonethoudivisionforexamplewillusuallytake2thoufromthediameterLargercommercial lathesaremuchmore likelytotakeoffonethoupergraduation)Nowtakesmallcutsuntilalmosttosizeusingpowerfeedif

you have it andmaking sure you knock the feed off before ithitsthechuckStopthelatheandwindthecarriagetothestart

of the bar Take another cut at the same setting andmake anoteofthediameterTakeanothershallowcutbutthistimegoonly about frac14in (6mm) along the bar knock the feed off andturn the lathe off Move the carriage towards the tailstock sothat you can measure the bar Continue making this cut andmeasureuntilthesizeiscorrectThenrunthetoolalongthefulllengthof the jobWindthecarriagebacktowardsthetailstockand take a finishing cut or two at the same setting ThediametershouldnowbetheexactsizerequiredIt is not difficult to turn accurately it just takes a little

patienceandpracticeThemoreturningyoudotheeasieryouwill find it is to hold accurate limits If you turn everythingaccuratelywhetheritneedstobeaccurateornotyouwillsoonlearntoturnwithinathouorsowithoutanyproblems

Measuringtheheightofthebarabovethecrossslide

Now we need to make a tool height setting gauge Cut alengthofbarjustoverthedimensionsyouwrotedownandfaceone end turn it round in the chuck and face the other endMeasurethelengthandfindouthowmuchyouhavetotakeoffit to give the dimension you want Put the bar back into thechuck and bring the tool up to the face of the bar Lock thecrossslideFacethebartolengthbyusingthetopslideindexmovingforwardsafewthouatatimeuntiltherequiredlength

is reached Younowhavea tool height settinggauge suitableforthefrontandreartoolsIf you have an inverted Vee bed lathe or if for any reason

youcanrsquotusetheheightgaugeflatonthebedyoucanputtheheightgaugeonaplateon topof the lathebedwhileyouaresettingthetoolheight

Settingtheheightgaugetothelathecentreheight

Settingtheheightofthetool

Usingthesettinggaugetosettheheightofthereartool

TurningtoaSpecificLengthandDiameter

Nowwewill turnabarwithastepon theendToensure thatthestep isthecorrect lengthwewilluseabedstopThiscanbe as simple as a block clamped to the lathe bed to stop thecarriage moving any further I use a simple home-made bedstopthatdoesallIrequireSetthebedstopthenmovethecarriageuntilittouchesthe

stop and lock it Wind the top slide so that the tool is justtouching the end of the bar and lock the carriage For thisexercise we will make the step 16mm long and 12mm indiameterWindthetopslidealong159mmWecannowroughout thestepateachendTurn theenddown toabout02mmabove the finisheddiameterbywinding thecarriagebackandforthYoucanusethe fine feedbutmakesureyouknockthefeed off before the carriage reaches the stop and finish up tothestopbyhandWindthetopslidealongtheremaining01mmto12mmandfinishthediametertosizeandlengthtakinglightcuts as previously Donrsquot forget to clean up the face of theshoulderyouhavejustturnedIfyouneedtouseabedstopatthetailstockendofthelathe

asimplemethodofdoingthisistouseabarplacedonthelathe

bed against the tailstock The bar acts as a stop when thecarriageiswoundbacktowardsthetailstockThistailstockendbed stop is useful when you are turning a groove in acomponentandyouneedstopssetatboth theheadstockandtailstockendsofthelathe

Ahome-madebedstop

TurningWorkontheOutsideoftheInsideJaws

Theoutsideoftheinside(drill)jawsareusefulforturninglargerdiameterwork that is too large to fit inside thedrill jawsThiswillmostoftenbe in the formofa flywheelcastingFlywheelswithsixspokesareidealforturninginathree-jawchuckasthespokes can fit between the chuck jaws Ideally you need totighten up the flywheel until it is tight but not so tight as todistorttherim

TurningasteponabarusingthestopThebarisheldinthethree-jawchuckandsupportedwiththetailstockcentre

Ausefultailstockendbackstopmethod

Holdingaflywheelinathree-jawchuck

Holdingaflywheelintheoutsidejaws

To ensure concentricity you should do as much work aspossibleonthecastingatthesametimeYoushouldbeabletoturntheoutsiderimofthecastingfacetherimfacethebossand drill bore and ream for the crankshaft all at the samesettingAllyouneedtodothenistofittheoutsidejawsreversethecastinginthechucktapitgentlybackontothestepsoftheoutsidejawsandfaceacrossthesecondsideoftherimandthehubUseabitofshimtoprotecttheflywheeldiameterItdoesnotmatter if the flywheel runs exactly true or not as you areonlyfacingitparallelandtowidthnotturninganydiametersto

size

UsingtheSoftJaws

Soft jaws are very useful when a component has to run deadtrue in the jaws for example when making something like agrindingspindlewhereconcentricityisimportantSoftjawslikelytobefoundinthehomeworkshoparesimple

rectangles of steel with the scroll and groove formed directlyintothesoftjawsAnothertypeofjawyoumaycomeacrosshasa grooved pattern in the main jaws that matches a similarpattern in theactualsoft jawsThesoft topsof these jawsareusually interchangeable They are more likely to be found onlarger chucks but you could make your own version for thesmallersizesofchuckifyouwishThemain use of soft jaws is for second operationwork for

examplewhenyouhaveturnedacomponentcomplete fromabitofbarandparteditoffNowyouneedtoholdthecomponenttruetofinishoffthesecondendYoucandothisbyboringoutthechuckjawstotheexactdiameteroftheworkpieceToborethesoft jawstheyshouldbetightened inthesame

direction as they will be tightened in use so that they areoperatingonthesamepartofthechuckscrolleverytimeIfyouhaveathincomponenttomachinefitthesoftjawstothechuckandtightenthejawsontoabitofbarheldinthechuckBesureto leaveenoughspace in frontof thebarsoyoucanbore thejawstofitthework

BoringsoftjawstofittheworkThejawsareclosedontoanoddmentofbartoturntheshallowregistersothatittakesthework

AlwaysusethesamechuckkeyholewhentighteningupthejawsThisappliestoanythingyoudowithaself-centringchuckStampacrossoracentrepopmarkagainstoneof the jaws IsuggestdoingthisnexttojawNo1butanyonewilldoaslongas you always use the samemarked hole Youmight as wellmarkallyourself-centringchucksinthesamemannerCarefullyborethejawstotheexactdiameteroftheworkto

be machined Try to get it exactly on size Undo the jawsslightly remove the bar and replace it with the workpiecewhichshouldnowrundeadtrueAusefulmodificationtothesoftjawsistodrillandtapahole

inthemiddleofthejawsandfitanAllenscrewtoeachholeIfyouwant toholda longbar in thesoft jaws it isnoweasy toboreallthewaythroughthejawsratherthanjustboringastepor part way through All you need to do now is find a disc ofmaterial to put into the chuck ensuring there is sufficientmaterialleftontheinsideedgesofthechuckjawstoborerightthroughtotakethebar

Holdthedisconthescrewheads ifnecessarydrillthediscbeforeboringBorerightthroughthediscandthejawsuntilyouarenearlytosizeatwhichpointyoucanborethroughthediscand test the resultingborewith theworkpieceMakesureyouclean the bore thoroughly before trying the workpiece sinceloose dust can make the hole seem smaller than it really isWhentheworkpieceenterstheborefinishboringrightthroughthe jawsgo througha coupleof timesat the samesetting totakeoutanyspringintheboringbarYoucannowremovethedisc clean the jaws and put the workpiece right through thechuckcheckingthatitrunsdeadtrueThisoperationmaysoundtimeconsumingforasingle item

but if you have several components to make it will save aconsiderable time on setting up each bar individually to runtrue

BoringsoftjawsusingaringThesoftjawshavethreeAllenscrewsthatarecloseddownontotheringwhileboring

TurningtheoutsideofthesoftjawsusingaringThesoftjawshavethreeAllenscrewsthatareopenedupontotheringwhileturning

NowthescrewsareinplacewecanworktheotherwayroundandholdcomponentsontheoutsideofthejawsTodothisyouwillneedaringofasuitablesizeontowhichyoucantightenthejawswith the jaw loading acting outwards so any componentyouputontheoutsideofthejawswillberunningconcentricallyThiswill be ideal for itemssuchas tractionenginewheel rimsandotherlargehollowortubularworkpiecesOne other use for soft jaws is to hold irregular-shaped

components Put a piece of bar into the soft jaws and bore aholeofanysizeand thencleanup theboreso thatallof thejawsare true Transfer the chuck to themillingmachine tableandclampitdownUseatestindicatortocheckthattheholeinthechuckistrueYou can now mill a nest to take any irregularly shaped

component confident that when the chuck is returned to thelatheitwillberunningtrue

Plungertypedialtestindicator

Levertypedialtestindicator

DialTestIndicators

Therearetwomaintypesofdialtestindicatortheplungertypedial test indicator as its name suggests works on a plungerprinciplewhilethelevertypedialtestindicatorhasastylusonthe end The lever stylus is usually ball-or pear-shaped and isfixedtothedialtestindicatorwithafrictionfitmeaningthatitcanbemovedupanddownontheendofthedialtestindicator

throughawidearctoputitintothebestpositionforuseThe plunger type dial indicator usually has a maximum

plungermovementoffrac12in (12mm)butplungermovementsofupto2in(50mm)areavailableTheplungertypedialindicatoris non-reversing and needs an adaptor to enable it to clockholes true Instead of a stylus it has an interchangeable endoften with a ball fitted various interchangeable ends areavailableoryoucanmakeyourownThe lever dial test indicator has a much smaller range of

travelarangeof0008in(02mm)isverycommonItisusuallyeither self-reversing (itmoveswhen in contact with theworkdependingonwhichwayitismoving)oritmaybereversedbyusinga lever on the sideof thedial test indicator both typesarequite commonSince the stylus isdelicate combinedwithitslimitedtravelrangeyoumustbeverycarefulnottobreakitAplungerdialindicatorcanbeusedasadirectreadoutofthe

travel and will be found to be very accurate Owing to therelativelylongtravelifyouwantedperhapstooffsetthecentreofabitofbar in the four-jawchuckby0125in (318mm) thiscanbedonebyturningthechuckbyhandandsettingthebaruntil the indicator travel shows 0250in (635mm) which is0125in (318mm) offset The lever dial test indicator is of nouseforgivingdirectreadingslikethisbutshouldbeusedasacomparatorwherethereadingtakenisforexamplezeroatallpointsofthetravelThedial test indicator is usuallymounted on amagnetic or

vacuum base but is sometimes fixed to a block that can beclampedtothelathemostoftenonthecrossslideSometimesthedialtestindicatorcomesasacompletekitincludingvariousmountingcomponents

Clockingtheendofacastinginafour-jawchuck

Four-jawChuck

To set thework up in an independent four-jaw chuckwe firstneed to know what part of the workpiece should be on thecentre If theworkpiece is a castingwemay have an outsidediameter or a hole that needs to run true in this case wewould put a dial test indicator onto the work and adjust thechuckalittleatatimeuntilthediameterrunstrueDonotturnthe chuck with the indicator in the hole Instead wind thecarriage forwards until the clock enters the hole and take areadingWind thecarriageback rotate thechuck90degreeswindthecarriageforwardandtakeanotherreadingAdjusttheworkinthechuckuntilitrunstrue

WhereacastingisstickingoutashereyoushouldtrytosupportthecastingwitharunningcentreThiswillhelptostopthecastingshiftinginthechuck

LatheCentreFinder

If there isnodiameterorholeyoumayhave tomarkout thecentreontheworkusingaheightgaugeandcentrepopitwithacentrepunchThenyoucanuseawobblerandatestindicatortosettheworktrueItwasoncepossibletogetalathecentrefinderconsistingof

a bar about 6in (150mm) long pointed at both ends with auniversaljointabout1in(25mm)fromthefrontendInusetheshortfrontendgoesinthecentrepopoftheworkinthechuckWhen you rotate the chuck by hand the pointed short endfollows the eccentricity of the centre hole which ismagnifiedaboutsixtimesatthetailstockendYouthenjusthavetoadjustthechuckuntilthetailstockendisrunningtrueatwhichpointthe centre in the work will also be running dead true I donrsquotknow anyone who makes these and second-hand ones areextremelyrare

Asimplehome-madecentrefinder

You can make a simple version of this that works well byusingamillingmachinepointedcentrefinderThisisaparallelbarwithaseparatemoveablepointedendThetwocomponentsare held together with a spring inside You need the pointededge finder a Morse taper parallel adaptor (the Morse tapershould fityour tailstock)aspringandashortstubofbar thatwillfitinsidethetaperedholderrsquosboretostopthespringgoingrightthroughPuttheshortstubofbarintothetaperinsertthespring follow up with the centre and put the Morse taperadaptorintothetailstockBringthetailstocktowardsthechuckuntil the centre of the centre finder is in the centre pop ThespringwillholditinplaceTousetheimprovisedcentrefinderput a dial test indicator onto the parallel part of the centrefinderrsquospointandrotatethechuckbyhandThepointwillrotateeccentricallyadjust thechuckuntil thecentre finderrsquospoint isrunningtrue

Usingascribingblockwithadialtestindicator

Move the tailstock along the bed until the point of thewobblerisinthecentrepopontheworkPutthetestindicatoronthefrontdiameterofthewobblerandadjustthechuckjawsuntilthewobblerisrunningtrueWhensettingupacastingorsomethingsimilarwherenotall

of the diameters are machined you should use the dial testindicator on diameters thatwill not bemachined such as theinsideofaflywheelrimWhenyouhaveturnedallthefinisheddiameters they should then be true with the unmachineddiametersSetting work in the four-jaw chuck depends on the

componenttobemachinedIfyouareusingroundmaterialyoucansetittoruntrueusingadialtestindicatorHoweverifyouaresettingaroughcastingthevariationofsizeandroughnessofthecastingsmaywellbeunsuitableforadialtestindicatorThere are alternativemethods of settingwork up in a four-

jawchuckespeciallyforcastingsOneofthesimplestmethodsis toholdasquarebar in the lathetoolholderandusethis tosetthejobtrueInuseyouwindthebaruptotheworkandsetthedial tozeroorotherwisemakeanoteofwhere it isWindthebaroutorawayfromtheworkTurnthechuck180degreesand wind the bar up against the work again You can

immediatelyseewhichwaythebarneedstomovesothatitisrunningtrueAdjustthecastinginthefour-jawchuckandmovethecastingtowardsthecentrepointRepeatuntilthecastingisrunning true This method is also useful if you are setting asquarebar to run true Justcheckeach faceof thesquarebarwiththebitofmetal

Settingacastingbyusingasquarebar

StickyPinMethod

An alternative the sticky pin method is especially suited tolocomotive wheels or flywheels An ordinary household pin ismounted in plasticine or Blu-tack perhaps stuck on the lathetool and is arranged to point to the inside diameter of thewheelor flywheel thearea that isnotmachinedbut is leftascastAdjustthecastinguntiltheunmachinedfaceisrunningastrueasyoucangetitandthewheelisreadytoturnThestickypinmethodisalsousefulforsettingupworkthathasachuckingspigot such as a locomotive smokebox door Just hold thechucking spigot in the four-jaw chuck and adjust the castinguntilitrunstrueontheoutsidediameterandthefrontface

Usingacommercialstickypintosetworktrue

Themethodsofcentringworkinthefour-jawchuckthathavebeen discussed are also suitable for setting work true on thefaceplate The next chapter looks at turning between centresandusingthefaceplate

6TurningbetweenCentresandFaceplateWork

Thischapterdealswithbasicturningbetweencentresandthenintroduces turning with the work mounted on the lathefaceplate

Headstockcentreanddriverplate(alsoknownasacatchplate)

TURNINGPLAINBARSBETWEENCENTRES

The most basic way of holding work for turning is between

centres Turning between centres is literally holding thecomponenttobemachinedbetweentwocentreseachofwhichhas a 60-degree included angle The headstock centre usuallygoes round with the headstockmandrel although some olderlatheshadanon-rotatingcentreandthedrivetotheworkwasbyapulleymountedontheworkThetailstockcentreisoftenafixedcentrethatdoesnotgoroundalthoughcentreswithballbearingscalledrunningcentresarereadilyavailable

Tailstockplaincentre

The component to be turned usually a shaft has a female60-degreecentreinbothendsthatisusedtosupporttheworkThe work can be turned round between centres so that bothends of the shaft can be machined Because the work ismountedbetweencentresbothendsoftheworkwillbetruetoeachother

Tailstockrunningcentreso-calledbecauseitrunsonballraces

CentringtheBar

FirstwehavetoputthecentresintoeachendofthebarIfthebarisshortsayuptoabout6inlongholdtheworkinthethree-jawchuckanduseacentredrillinthetailstockdrillchucktoputacentre intothebarAcentredrill isashortdrillwithasmallpilot on the end that has a 60-degree taper to the bodydiameterAbettermethodof centring thebar especially longbars is by using a three-jaw chuck and the fixed steady Thebarisheldinthethree-jawchuckwiththeotherendsupportedin the fixedsteadyand thecentre is formed in theendwithacentredrillAusefultoolthatcanbeusedtofindthecentreoftheshaftis

thecentresquarewhichisametalbladewithaVeeonitthatlocatesonthediameterofthebarMarkalineacrosstheendofthebarwitha scriber turn the centre square90degreesandthenscribeanotherlineWherethetwolinescrossisthecentreof thebar Tomake it easier to see the scribed linesblackenthe end of the bar with a permanent felt tip marker beforescribingCentrepunchthepointwherethetwolinescrossandput a 60-degree centre in each end of the bar using a centre

drill in a power drillHold thebar in a bench vicewhile doingthisPutacentredrillintothetailstockdrillchuckandinsertthebar in the three-jaw chuck Make sure the lathe is on a lowspeedabout300rpmwindthetailstockinandjustlightlycleanupthecentreholewiththecentredrilltotrueitupAnotherusefultooltofindthecentreofabarisabellcentre

punchThiscomprisesaconewithacentrepunchinthemiddleIn use place the bell end on the end of the bar and tap thecentrepunchwithahammertomarkthecentreTheendofthebar though needs to be reasonably square if using the bellpunchmethodThere are other similarmethods of centring bars but those

givenherewillbealltheturnerneedstolearn

Turningbetweencentres

Centringthebarusingthefixedsteady(Notethatthefrontclampisnormallydoneupwhileinuse)

Asimplecentresquare

Crosssectionofbellcentrepunch

MachiningtheBar

NowweneedtomountthebarbetweencentresThisissimplyamatterofputtingthebarbetweencentresandtighteningthetailstocksoitislightlypressingintothecentreintheendofthework To drive the work a carrier is fixed to the shaft andengagesapininacatchplatemountedonthelathemandrelAcatchplateissimplyablankdiscwithapinstickingouttodrivethecarrierthat isfittedtotheworkThecarrier isfittedtotheworkusinganAllenscreworboltTostopanymovementofthebarinrelationtothecatchplatethecarriercanbewiredtothecatchplatepinThiswill stop thecarrierand thework flappingaboutItisparticularlyimportanttostoptheworkfrommovingin relation to the catchplate when screwcutting betweencentres

Facingoffabarusingthehalfcentre

Nowthatthebarissafelymountedbetweencentreswecanstart turning it tosizeNormally the first thing todo is to facetheendsofthebartothefinishedlengthDecidewhichendofthebarhastheshallowercentreWewillmachinethisendfirstYouwillneedahalfcentreso-calledbecausealmosthalfofthecentre is missing This means the lathe tool can reach rightacrosstheendoftheworkwithouttouchingthehalfcentreWhenusinganyfixedcentreinthetailstockputabitofoilor

grease into the centre before use and top up as necessaryLightlywindthetailstockbarrelagainstthecentreandlockthebarrel so it canrsquotmoveSwitch the latheonandwind the toolacross to clean up the end Reverse the work and clean theotherendupat thesamesettingBothcentresshouldnowbethesamedepthMeasuretheoveralllengthofthebarTakethefinished length required from the overall measurement youhavejustmeasuredDividethisbytwoandthisishowmuchweneed to take off each end of the shaft so it finishes at therequiredlength

Askimmedbar

Ifyouhaveonechangethetailstockhalfcentretoarunningcentre if you donrsquot have a running centre change to a fixedcentreThehalfcentreshouldonlybeusedwhenfacingtheend

of the bar We will nowmachine the rest of the bar For thepurposeofthisexamplewewillassumethebarhasafinisheddiameter in themiddle with a step at each end First we willmachine the overall diameter to size To do this we need toskimthediameterandcheckthesizeTakeafinecutalongthebarusingthefinefeedifyouhaveoneMeasurebothendsofthebar Ifyouhavesetthelatheupcorrectly(seeChapter2)thebarshouldbeparallelIfitisnotadjustthetailstockbeforecontinuingAssumingthebarisparalleltakeanothercutortwosothatyouareabout01mmlargerthanthefinisheddiameterNowmove the tool in until almost at finished size and take alight cut about 10mm long along the bar Repeat this cut toensure the tool is notpushingoffMeasure thisdiameter youwill probablyhave towind the tailstockbarrel back toget themicrometerontotheendofthebarOnlymovethebarrelbackdo not slide the entire tailstock backMeasure the bar to findouthowmuchtoremovefromthediameterTakeanothershortcutandcheckforsizeWhenthebariscuttingtosizemachineall thewayalongYouwillprobablyhave to take twoor threecuts at the same setting until the bar ismachined to finishedsizeNowwewill turn the stepson theends Toensure that the

stepsare thecorrect lengthwewilluse thebedstopSet thebedstopthenwindthetopslidesothatthetoolisjusttouchingthe end of the bar For this exercise we will make the steps12mm long Wind the top slide along until the tool is justtouching the end of the turned bar Wind the top slide along119mmWecannowroughoutthestepateachendTurntheenddowntoabout02mmabovethefinisheddiameterYoucanusethefinefeedbutmakesureyouknockthefeedoffbeforethecarriagereachesthestopandfinishuptotheendbyhandRepeat for the other end Wind the top slide along theremaining01mmto12mmandfinisheachendinthesamewayasyoufinishedthemaindiameterDonrsquotforgettocleanupthefaceoftheshoulderyouhavejustturnedCongratulations you have just turned an accurate shaft

Donrsquotworryiftheshaftisatinybitundersizeyoucanprobably

makethematingholestofit

Thefinishedshaft

Usingachuckandarunningcentre

Usingthemethodsetoutaboveyoushouldnowbeabletoturn any shaft you require within the capacity of the lathe Avariationoftheabovemethodwheretheshaftissingle-endedistoholdoneendinthethree-orfour-jawchuckandsupporttheotherendwithacentreinthetailstock

Alargefaceplatesmalleronesareavailable

FACEPLATEWORK

Another basic way of holding work is on the faceplate Thismethod is used when the component is too large or isawkwardly shaped andwould be difficult to hold in a three-orfour-jaw chuck Usually the work is clamped directly onto thefaceplate often with a packing piece behind it to protect thefaceplateThefaceplateshouldbeflatandtruesothefirstthingtodo

whenyougetthelatheistocheckthefaceplatewithadialtestindicatorCarefullycleanthemandrelnoseandtheinternalholeinthefaceplateMakesurethemandrelcanturnfreelybyhandwith the lathe switched off and check that the face of thefaceplateisrunningtrueasclosetotheouteredgeasyoucanget If it is runningtrue runthetest indicatoracross the frontfaceofthefaceplatethisshouldbetrueaswellIfthefaceplateis running out itwill need to bemachined Put the lathe intobackgear if ithas it (topbackgearwillprobablybe fine)Youwill need a carbide-tipped tool ideallywith a small 45-degreechamferonthetipBringthetooluptothefaceplateand lockthe carriage Next you need to lightly face the faceplate right

acrossitsdiameterIfyouhaveapowercrossfeeditwillmakelight work of this but if not you can feed across by handFortunatelymost faceplateshavea series of rings on them toaid in setting up the work Machine the faceplate from theoutsidetothefirstringandstopforarest feedtothesecondring and so on until finished Depending upon how badly outyourfaceplateisyoumayhavetodothismorethanonceuntilit iscleanedupbutwhen it isdoneyouwill rarelyneedtodothisexerciseagain

Machiningaholeinablock

Asmentionedpreviously the ringsmachined on the faceplateareguidestohelpyousetuptheworkThiswilldoiftheworkisaroundcomponentbutweneedadifferentmethodiftheworkis square Take a block of metal for example that has beenmachinedalloverWewanttomachineaholeinit2infromoneedgeand1in fromanother edgeMarkout thepositionof theholeandcentrepunch it Put adeadcentre into the tailstockholdtheblockontothefaceplatebringthetailstockuptowardsthechuckandlockitWindthetailstockbarrelandcentreuptothe component and engage with the centre pop Lock thetailstock barrel Clamp the block to the faceplate using somepackingpiecesandfourclampsontheblockTheholeisnowoncentreandwecanmachineitinthecorrectplaceIf we need more than one hole placed accurately in the

componentwecanusetoolmakerrsquosbuttonstoensuretheholesare in the correct place Toolmakerrsquos buttons usually come insetsof fourOnebutton isusually longer than the rest soyoucanstillclockthediameterwhenitisclosetoanotherholeSetsare often available second-hand on eBaywhile they probablyhaveanobscureAmerican threadyoucanclamp themto theblock using your own BA or metric screws together with awasher

Settingupthefaceplateusingthetailstock

Asetoftoolmakerrsquosbuttons

Tofitthemtothecomponenttobeboredmarkoutdrillandtap holes in the approximate positions where the holes areneeded If you need a pair of parallel holes place thecomponentonasurfaceplate looselyfitthebuttonsandpushthem down onto a parallel or similar block of the correctthicknessandnipthescrewsupThespacershouldbesmallerthanrequiredbyhalfthediameterofabuttonIftheholesneedtobeacertaindistanceapartuseaspacer

of the correct size between the buttons (Remember tomake

thespacersmallerbyonediameterofthebutton)

Settingupacomponentusingtoolmakerrsquosbuttonstogetafixeddistancefromtheedgeofacomponent

TherearelotsofdifferentwaystosetthespacingofbuttonsItismainlyamatterofcommonsenseCastingsandflatcomponentscanbeboltedtothefaceplate

for machining A typical example of a flat component is aneccentric strap This type of component is usually made of acomponentthatiscutinhalfandboltedbacktogetherAholeisthenboredinitonthecentrelinetofittheeccentricThistypeofcomponentisoftendifficulttoholdinthelathechuckandisprone to distortion Castings are often too large to fit into alathechuckandso the faceplate iscalledon toundertake theworkAcastingcanoftenbebolteddirectlytothefaceplatetofacilitateeasymachining

Settingupacomponentusingtoolmakerrsquosbuttonstogetafixeddistancebetweenthecentresofacomponent

Work on the faceplate is often an odd shape or is set off

centreThiscauses it tobeunbalancedandasaconsequencethe lathemayvibratewhile thework is turningTocounteractthis tendency the faceplate should be counterbalanced byboltingweightsontoitAusefulsourceofweightsisthelathersquoschange wheels By bolting a change wheel or two onto thelightersideofthefaceplateyoucanbringthewholeassemblybackintobalanceAfterboltingthechangewheelsonspinthelathe by hand to check the balance The faceplate should notshowatendencytostopatoneparticularpointWhenyouarehappy that the faceplate is in balance the work and balanceweightsareboltedontightlyandsothattheworkdoesnotfoulthe lathewhen turnedbyhand switch themachine on in lowback gear to check for vibration Depending on what you areturning you should be able to run in top back gear or evenbottomdirectspeed

Asimpleclampsetisveryusefulwhenmachiningacastingonthefaceplate

TurningaFlywheel

Oneofthemainusesofafaceplateisturningalargediameteriron casting typically a flywheel or a locomotive wheel for asteamengineTheflywheelshouldbemountedsothattheinneredgeoftherimandtheouteredgeofthehubruntrueIfeitherofthemrunsoutitwouldbebetterthatthehubrunsoutasthe

rimwillbemorenoticeableonthefinishedengineClamp the flywheel down with some packing under the

spokessothatyoucanturnrightacrosstherimBecarefulthatyouclamptheflywheeltightenoughsothat itdoesnotmovebutnotsotightthatitdistortsRoughturn theoutsidediameterand facetherimusingthe

backgearUsingadirectdrivespeeddrillandborethecentrehole and either finish off with the boring tool or use a reamDonrsquot try reamingwithout boring the chances are that if youdotheholewillnotbetruewiththerimasthedrillprobablydidnotcutanaccurateholeDropdowntothetopbackgearspeedface the rim and turn the outside of the rim to the finisheddiameter Turn the flywheel over and finish the other face towidth

Astubarborsuitableforcentralizingalocomotivewheelorflywheel

TurningLocomotiveWheelFlanges

LocomotivewheelflangescanbeturnedonafaceplateYoucanpurchase blank end Morse taper arbors that fit into theheadstocktaperFitoneoftheseandturnaspigotonittotake

thewheel bore Thewheel bores should all be the same sizebut if they are different sizes machine the spigot to fit thelargestboremachinetheflangeonthatonethenmachinethespigotdowntofitthenextonemachinetheflangeandsoonIdeally the wheel bores should all be the same size but if

theyarenotproceedas followsSkimtheoutsidediameterofthe wheel flangemeasure and take it to the correct finishedsizeMovethelathetoolinbythedepthoftheflangeandturnthe tread Deal with all wheels like this machining all of theflangeoutsidediameterstothesamesizemovinginthecrossslidebythesameamounteachtimesothatallthetreadsendupthesamesize

UsingtheKeatsVeeangleplatetoturnaneccentriccomponent

KeatsVeeAnglePlate

TheKeatsVeeangleplate ismountedon the faceplateand isusedtoholdroundbarsquarebarandmiscellaneouscastingssuch as cylinders and steam chests The angle plate can bemountedanywhereonthefaceplateaslongasthelathecanbe

rotated safely and is in balance When spun by hand thefaceplateshouldnotshowatendencytostopatanyparticularplacewhenrununderpowerthelatheshouldnotvibrateAswellasholdingbarandcastingsforturningtheKeatsVee

angleplateisveryusefulformakingeccentriccomponentssuchastheeccentricsforasteamengineTo turn an eccentric use a test indicator to check that the

roundbarisrunningreasonablytrueWhenthisissatisfactoryyoucanturntheoutsidediameterofthebartofittheeccentricstrap (or component) including any step or groove requiredNextoffsettheKeatsVeeangleplatebytheamountyouwantthe eccentric lsquothrowrsquo to be Use the dial test indicator tomeasure the offset of the outside of the eccentric The offsetshouldbetwicethethrowYoucannowdrillboreandreamtheholeintheeccentricYounowhaveenoughbasic knowledge to carryout turning

between centres andwork accurately on the faceplate In thenext chapterwewill lookat holdingwork in a collet andonamandrel

7ColletsandMandrels

Thischapterexplainsallaboutholdingworkinacolletandhowyou canmake and use several different types of mandrel forworkholding

ERcollets

USINGCOLLETS

Quite a few different collet systems are to be found inworkshops Some are used for holding tools such as millingcutterssomeareusedforbarorworkpieceswhilesomemaybeusedwithbothbarandworkpiecesOne of the commonest is the ER collet which comes in

severaldifferent sizeseachhavingadifferent largediameterTheERcolletsystemallowsupto0039in(1mm)collapseofa

colletalthough in thesmaller sizesyoucanbuy thecollets in05mmincrementsA16mmcolletforexamplewillholdroundmaterialdownto15mmdiameterWhatevertheERcolletsizetheyallappear togodownto1mmminimumwhichwillclosedownto05mm

ERcolletadaptor

TherearemanytypesandsizesofERholderavailableAlltheusualMorse taper shank sizes are available and you can alsobuyvariousdiametersofextendedparallel shankholdersTheproblemwiththeseisthattheyaregreatforholdingtoolsthathave a short shank but because you need to use the holderwithadrawbaryoucanrsquotputlongbarstockrightthroughthemTo overcome this for lathe work you can also buy ER colletholdersdesignedtobefittedtoachuckbackplatethatyoucanmachine to suit your lathe so ensuring good concentricityBecause they donrsquot use a drawbar you can fit bar stock rightthroughandintotheheadstockmandrel

ERcolletadaptorfittedtoabackplateIalwaysleavebackplatesoversizesoIhavesomethingwithwhichtoclampthemdownwhenusedonamillordrill

When buying new and second-hand ER collets make surethey have the retaining groove near the nose end The older(andobsolete)EandEScollet typesdonothavetheretaininggrooveandarenotinter-changeableYouaremostlikelytofindEandEScolletsincludedwithasecond-handUnimatlatheDraw-in collets are usedwith a drawbar or collet tube The

drawbardrawsthecolletuptightbydrawingit intothelathersquosmandrelbyabar that runs through thecentreof themandreland screws into the centre of the collet Thismeans that youcannotputbarstockrightthroughthecolletToovercomethissome Morse taper collets use a hollow draw tube the collethaving an external thread tomatch the internal thread of thedrawtube

Draw-incollet

Special collets are made for the Myford ML7 Super 7 andML10 lathes These are Morse taper collets but rather thanhavingadrawbartheyareclosedwithanoseringthatfitsoveragrooveinthecolletThenoseringtightensthecolletintotheheadstockmandrelrsquos Morse taper It is extracted after use byundoing the nose piece which draws the collet out from theMorsetaperbythenosegrooveImperialandmetriccolletsareavailableuptofrac12in(12mm)diameterDead lengthcolletsareavailable that fit intoanattachment

usually fixed to the front of the lathersquosmandrel These colletsarecalleddeadlengthbecausetheydonotmovelongitudinallyunlike draw-in collets You are more likely to find collets likethesesecond-handratherthannew

BoxedsetofMyfordcollets

Deadlengthcollet

AvariationofthedeadlengthcolletistheCrawfordMultiborecolletThissystemhascolletsmadeofsegmentsheldtogetherbyspringsThecolletsareofvariablediameterandhavequitea

largeclosurerangeTheyaremorelikelytobefoundonalargercommercial lathe although you can get collets for smallermachinesWatchmakerrsquoscolletscanbeused inmost lathesbymaking

an adaptor for the headstock and a drawbar (or tube)Watchmakerrsquos collets are very accurate and can go down toverysmallsizesbuttheyhavelimiteduseinmostworkshopsYou can get a special watchmakerrsquos spindle for the EmcoUnimatlatheandthereisalsoaversionoftheCowellslathetheCW90thattakeswatchmakerrsquoscolletsFormost of thework carried out on the lathe youwill find

thatanERholder thatmountsontoachuckbackplate ismostuseful

Simpleexpandingmandrel

Simpleplainmandrel

MAKINGMANDRELS

There are several types of mandrel in common use inworkshops The most common is probably the expandingmandrelwhichcaneasilybemadeinanyworkshopInitsmostbasic form it is a bar turned to a size to fit the bore in theworkpieceItisthenthreadedwithataperedtapandslitat90degrees togive foursegmentswhichare thenexpandedbyascrewfittedintotheendofthemandrelAnother common mandrel is the tapered mandrel This is

usuallyalsquobetweencentresrsquomandrelandisoftenmadetotaperfromjustacoupleofthouovernominalsizetoacoupleofthouunder nominal size It is usually hardened and has a groundfinishTheworkpieceisheldinplacebybeingpushedontothemandreluntilitistightToremoveitjustpressitbackoutthewayitwentinWhereconcentricityisnotquitesoimportanttheworkpiece

canbeputonaplain turnedmandrelandtightenedupwithaboltandflatwasherExpandingmandrelsarealsomadecommerciallybutasyou

need a mandrel for each individual size of hole it can getexpensive if you need more than one or two different sizesCommercialmandrelscanbeobtainedwithMorsetapershanksto plug straight into the headstock Thismethod ensures thatthe mandrel should run dead true assuming both the Morsetapermandrel and theMorse taper in the headstock are bothcleanandfreefrommarksorswarfYou can also purchase Morse taper arbors with blank end

pieces from which to make your own mandrels First we willmake an expandingmandrel from a blank Morse taper arborYouwillneedtoturnthearbordowntofittheworkpieceboreIusually turn themandrelabout0010in (0025mm)oversize tostartwithandthenIdrillandtapthearborwithataperedtapThe drilled hole can go quite deep but the tapped hole onlyneedstogoinuntilthelockingbolt isabouthalfwaydownthelengthwheretheworkpiecewillsitPut the mandrel into the vice and cut along the mandrel

making four cuts around the circumferenceRetap thehole to

cleartheswarf fromthethreadandputthemandrelback intothe headstock taper Now you can lightly nip the screw up toexpandthemandrelslightlySkimthemandrel to finishedsizeuntil the workpiece will fit on without shake You can nowfurther tighten the screw so that the workpiece tightens ontothe mandrel When you slacken the screw the workpiece willcome off easily as you have skimmed it while it was slightlyexpandedYoucanmakeanexpandingmandrelfromabarheldin the three-or four-jawchuckorperhapsacollet inasimilarway Ifheld inachuck itmaynotgoback true ifyouneed touseitagainsoifpossibleyoushouldholdthearborinacolletFor aplainmandrel turn thediameter to fit theworkpiece

anddrillandtapforacapscreworaboltThereisnoneedtosplit this type ofmandrel You simply put the workpiece ontothemandrelandholditonwithaflatwasherAgainitdoesnotmatterwhetheryouuseabarinachuckorcolletorifyouusea Morse Taper blank arbor Arbors are very useful in theworkshop If youmake them fromMorse taper blanks or holdtheminacollettheycanbeusedoverandoveragain

8TaperTurningandLatheAccessories

Thischapterexplainshowyoucanturnataperusingatopslidetheuseoffixedandtravellingsteadiesandformtools

Turningataperwiththetopslide

TAPERTURNING

SometimesyouwillhavetoturnataperintheworkshopThatisa fairly easy jobWhat ismore difficult however is having toturnmatchingmaleandfemaletapers

Themethodyouaremostlikelytouseintheworkshopistoturn the two tapers with the top slide You should be able toturna taper longenough foraMorsetaperusingthismethodThemostimportantthingwhenturningtapersistoensurethatthe tool tip is at the exact centre height of the lathe This isbecause the taper will vary if the tool is not dead-on centreheightProbably the easiestmethod of turning aMorse taper is to

useadial test indicator toclocka lathecentreof therequiredMorse taper between centres The smaller end of the tapershouldbeatthetailstockendofthelatheThetopslideshouldbewoundalongthetaperby itshandwheelwhilethecarriageremainslockedThetopslideshouldbeadjustedangularlyuntilthedialtestindicatorreadszeroallthewayalongNowyoucanfinish turn the external Morse taper using an internal MorsetapersleeveasagaugetocheckthattheangleiscorrectTodothis make marks with a felt tipped pen along the taper andcheck that the test sleeve rubs evenly all the way along themaletaperAdjustifnecessaryuntilyouhaveaperfectfitToturnthematchingfemaletaperthelargeendofthetaper

willbeat the tailstockendand theboringbarwillbe invertedandcuttingon thebackof theholeDoing thismeans thataslongasbothofthetoolsareatcentreheightthetapersshouldmatchWecanusethemaletaperthathasjustbeenturnedasatestbarBoreoutthetaperverycarefullyyouwonrsquotneedtoremovemuchmaterial before the test taper goes too far intothe finishedbore Testwitha felt tippedpenuntil youhaveaperfectfitYou can turn any taper you need this way you are not

restrictedtoMorsetapersAnothermethodmostoftenusedforlongshallowtapersistouseataperturningattachmentTheseattachments are often available as extras on higher qualitylathes They comprise a slide mounted onto the back of thelathe Often the guide is dovetailed with a sliding blockattached to the cross slide to guide the tool on a taper ThedepthofcutisusuallyputonusingthetopslidesincethecrossslideisusuallydisconnectedfromthefeedscrewInthiswayit

isfreetomoveinandoutcontrolledbytheguide

Taperturningattachment

Settingthetopslidebyclockinganexistingtaper

Anothermethodweshalllookatfortaperturningistooffsetthe tailstock on its base This will make the work turnedbetween centres become tapered either large or small at thetailstockenddependingonwhichwaythe tailstock isoffset ifsettowardsthebackofthelathethediameterwillbelargerat

the tailstock end if the tailstock is moved to the front thetailstockendwill be smaller indiameter Theamountof taperthatcanbeturnedinthismannerislimitedsincetheheadstockandtailstockcentresareoutoflineThe final method of offsetting the workpiece is by using a

boringhead inthetailstockYouneedahome-madehardenedsolidcentrethatfitswheretheboringtoolwouldnormallygo(AsmallUnimatlathesizerunningcentremightbeideal)SettheboringheadsothetooltravelishorizontalYoucanthenoffsettheboringheadcentresocreatingataperThisisthesameassetting the tailstock over but you donrsquot have to realign thetailstockafterwards

Usingthefixedsteady

USINGFIXEDANDTRAVELLINGSTEADIES

The fixedsteady isusedmainly to turn theendofabaror tocentre a workpiece that is too large to fit through the chuckObviously bar stock should not protrude from the chuckmorethan is necessary to work on This is where the fixed steadycomesinThefixedsteadycanbesettothediameterofthebarsothattheendofthebarcanbemachinedsafely

Thesteadycanbesetusingachuckmountedonthistailstockadaptor

Travellingsteady

Settingthesteadybyusingachuckmountedonanadaptor

Onewaytosetthefixedsteadytosizeistoturnabitofbarin the chuck to the same size as the barwewant to use thesteadyonThenwecanmovethefixedsteadyalongthelathebedandfittheworkpieceintothechuckandinthesteadyTheendof thebar nearest to the tailstock shouldnowbe runningtrueandcanbeworkedonsafelyThebarcanbecentredrilledfacedorotherwiseworkedonAn alternative way to set the steady is to support the

tailstockendof thebarwitha threejawchuckmounted in thetailstockAdaptors to take the threejawchuckareavailableoryoucouldmakeyourownJustsupportthebaratbothendsinthethreejawchucksandsetthesteadyfingerstothebarThe fixed steadycanalsobeused to support tubes thatdo

nothaveanymaterialinthecentreThe fingers of the steady need to be lubricated regularly

while inuseThis iseasilydonebydrillinga smallhole in thetopfingerwithacountersinkinsidetheslottotakeoilThetravellingsteady ismostoftenusedwhenturningdown

small diameterbarsor screwcutting long slenderbars It boltsonto the front of the cross slide in line with the chuck and

travelsalongwhenthecrossslideismovedalongthelathebedWhen turning the travelling steady can either be set to thediameterofthebarbeforeturningandtoleadthetooloritcanbesettothefinisheddiameterrequiredandtofollowthetoolNormallythefingersaresetto leadtheturningtoolbut if thebarisroughforexampleifitisdentedorrustyitisbetterforthefingerstotrailtheturningtoolIfscrewcuttingthetravellingsteadyshould lead the toolso that itdoesnotdeflectorwearduetoaburrbeingthrownupbythescrewcuttingtoolSteadies will not be used very often but they are

indispensableontheoccasionswhentheyareneeded

Travellingsteadywithleadingfingers

Travellingsteadywithtrailingfingers

MAKINGASIMPLEFORMTOOL

Youmay often need to produce a particular shape such as aradiusonacomponentTheeasiestmethodtodothisiswithaformtoolAsanexamplewewillmakeasimpleformtooltocutahalfcircleonabarofbrassForaradiusof3mmforexampleweneedtoproducea formtoolusinga6mmdiameterdrillorreamFormaterialwewillusegaugeplateahighcarbonsteelthatcomesintheformofagroundflatbarApieceabout5mmthick and10mmwide is needed although the size is not thatimportantaslongasthegaugeplateisthickenoughtoabsorbanyturningstressesIdeallyweneedataperedreamerthatwillproduce a 6mm diameter hole somewhere along its lengthalthough you could use a parallel 6mm reamer a slot drill orendmillorevenastandardtwistdrillDrill a hole through the gauge plate and open up to 6mm

diameterAim togetagoodsurface finishon thesidesof thehole Hacksaw and file half the hole away to leave the shaperequired on the finish turned component Now we need to

harden the tool although ifweare justdoingacomponentortwoinbrasswecouldprobablygetawaywithouthardeningitHardeningissimpleenoughheattheworkingendofthetool

toredstopheatingandletthegaugeplaterestforacoupleofminutesThiswillgive thegaugeplateachance tochange itsinternalstructureReheattoredandquenchinatubofwaterThisshouldhardenthetoolAlthoughabitbrittle itshouldbefine for making a few components Stone the top of the tooluntil thecuttingedge issharp Ifnecessaryyoucanpolishtheinside of the radius that is going to do the cutting There areseveralmethodsyoucanuse includingapieceofwetanddrypaperaroundabitofbaraverysmallgrindingwheelcalledamounted point or a bit of round bar with fine valve grindingcompoundonitWhicheveryouuseaimforapolishedfinishasthe finish on the turned component is directly related to thefinish on the form tool You canmakeall sorts of simple formtools with gauge plate a typical example being a facing toolwitha30-degreechamfertofaceandchamfernuts

CopytemplatereadytouseMetal

MachiningfromaTemplate

MachiningfromaTemplate

YoucanmachineaprofilefromasimpletemplateThetemplatecanbecutfromgaugeplatewithafileormachinedbutitdoesnot need to be hardened The template could be used tomachinea large radius suchasa smokeboxdoor Inuse thetemplateismountedonablockonthelathebedandthecrossslide is kept in contact with the template by being pushedagainstthetemplatewithaballracefixedtothecrossslideInthenextchapterwewillbelookingatdrillingandreaming

9DrillingandReaming

ThischapterexplainshowtousedrillsandreamersinthelatheTherearemanydifferenttypesofdrillsandreamersTheyareessentialtomakingcomponentsinthelatheWewilllookatthevarioustypesandhowtochoosethespeedsandfeedsforusingthem

Thisdrillchuckrequiresachuckkey

TYPESOFDRILL

Drills are normally held either in the tailstock if they have aMorsetaperor inadrillchuckiftheyhaveaparallelshankA

drillchuckismountedonaMorsetapershankthatisusuallythelargestMorsetaperthatthetailstockwilltakeThelargestsizeof drill that will normally fit a drill chuck is frac12in (13mm) indiameter although larger chucks are available at a cost Thesmallest sizeofdrill thatafrac12in (13mm)drill chuckwill take isusually about 116in (15mm) This is because the larger drillchuck is incapableofclosingdownenoughto take thesmallersizesofdrillThismeanswewillprobablyneedtwodrillchucksoneforlargerdrillsandoneforsmallerdrills

Hand-tighteningdrillchuck

TherearetwomaintypesofdrillchuckOneistightenedbyusinga chuckkeywhichhasa small bevelgearbuilt on to itthatmates with the outer sleeve of the drill chuck itself Theother type is hand tightenedwhere the outer chuck sleeve isknurledtotightenthedrillthesleeveisturnedbyhandLargerdrillsabovefrac12in(13mm)usuallyhaveaNo1orNo2

MorsetapershankYoucangetMorsetapersleevestoconvertalargeMorsetoasmallerMorsetaperYoucanalsogetasmallMorsetolargeMorsetaperconverteraswell

Drillwithataperedshank

Some larger drills are also available with parallel shanksTheyaremadewithasteppeddownfrac12inparallelshankandarecalledblacksmithrsquosdrills

Blacksmithrsquosdrill

Themostusefuldrills in theworkshopcomeassetsofhighspeedsteeljobberdrillsinacaseThemostpopularsetcovers1mmto6mm increasingby01mmstepsAnotheruseful setcoversfrom6mmto10mmalsoincreasingby01mmstepsIfyouareintomodelengineeringasetofnumberdrillsfromNo1toNo60istoberecommended

Asetofmetricdrillscovering1ndash6mm

Drills are also available in different lengths Stub drills areshorter than standard jobber drills Several lengths of longseries drills are also available ranging from one and a halftimesthelengthofajobberdrilluptoseveraltimesthelength

Differentlengthsofdrills

Mostdrillshavetwoflutesbutcoredrillsarealsotobehadwith three four or evenmore flutes As their name suggeststhese are usually used for drilling out cored holes in castings

CoredrillsarenotnormallycapableofstartinganewholebutareusedforopeningupexistingholesAstandarddrillusuallyhasanincludedangleof118degrees

Stub drills and cobalt drills often have a 135 to 140 degreeangle for use on hardermaterials such as stainless steel andaircraftsteelsBack rakeondrills is oftenground radially Another typeof

pointhoweverhasfourfacetstothepointFour-facetdrillsaremuch better at starting a hole than a standard jobber drillwhich tends towanderunless followingacentrepoporcentredrill Four-facet drills also require less pressure to drill a holesincethepointisthinnerthanastandarddrillandtheyarefareasier to sharpen accurately by hand than standard jobberdrillsDormerdoarangeoffour-facetdrillscalledA002withatitaniumnitridecoating(TiN)andafour-facetpoint

Three-flutecoredrill

DormerA002four-facetdrillpoint

To drill an accurate sized hole requires two ormore stepsfirst youdrill the hole undersize (by perhapsfrac12mm) then youfollowthroughwithasizedrillThechancesaretheseconddrillwillcutdeadtosizeasitisonlycuttingasmallamountfromthediameter Obviously if you are drilling a large hole moreintermediatestepsmayberequiredSpeedsfordrillingarethesameasthosegivenforturninginthetableinChapter3

Setofcentredrills

REAMERS

There are several types of reamers available for use inworkshops again with either Morse taper or parallel shanksSomehavesizeparallelshankstheshankbeingthesamesizeas the reamer while others are availablewith shanks smallerthanthereamedsizeThereisalsothewaistedreamerwheretheshankisthesamesizeasthereamerthemiddleissmaller(waisted)andthecuttingendistheholesizeYoucanalsogetadjustablereamerswheretheendisexpandedbytheuseofascrewinthecuttingendofthereamer

Handreamerthefrontparthasaslighttaper

Straightshankmachinereamer

Waistedshankmachinereamer

Morsetapershankmachinereamer

Parallelreamersaredividedintotwotypesparallelmachinereamerswhere thecuttingdiameter is thesameallalong theream and hand reamers where the cutting end is slightlysmallerandtapersuptothefulldiameterWhen drilling a hole for reaming it is advisable to use the

two-holemethodfordrillingYouaremore likelytogetagoodsize hole prior to reaming For small reamers up to 04in(10mm) leave about 0012in (03mm) for the reamer toremoveForreamersuptofrac34in(19mm)leave0016in(04mm)and over frac12in (13mm) leave 0020in (05mm) For reamingspeedsuseabouta third toahalfof thedrillingspeed for thesamediameterFeedsshouldbefrom0002to0004in(0025ndash005mm)per toothper revMultiply the feedper toothby thenumberofteethtogivethefeedperrevolutionItisbesttouseneatcuttingoilformostmaterialsexceptfor

aluminiumforwhichparaffinshouldbeusedandplasticwhichrequirescompressedairorplainwaterYoushouldnotuseoilasacuttinglubricantforanytypeofplasticasitcanattackandordegradetheplastic

10BoringToolsandBoringHeads

Thischaptershowsyouhowtoboreholesinthelathewiththeworkheldinachuckmountedonthefaceplateorfixedtothelathecrossslide

TypicalHSSboringbar

DIFFERENTTYPESOFBORINGBARS

BoringaholetosizeisoneofthemostexactingjobsyoucandoinalatheItisrelativelyeasytoturnashafttofitaholebutitis much harder to bore an accurate hole to fit a shaft Ifpossibleyoushouldboretheholebeforeturningtheshaft

YouarelikelytocomeacrossHSSboringbarsorinsertedtipboringbarsBothhavetheirusesTheHSStoolisidealformostgeneralhole-boringjobsbuttheinsertedtiptoolisfarsuperiorfor materials such as cast iron The boring bar should be aslargeasyoucangetintotheholewhilestillallowingswarftoberemovedTheboringbarshouldonlyprotrudefarenoughtoenableitto

go completely through the bore Any more protrusion than isnecessarymay result in chatter or a dig in in the bore Thefront clearance on the boring bar tip should be as small aspossiblewithoutrubbingasstrengthisimportantBoringcanbeusedtofinishaholetosizeorsimplytotruea

holeupafterdrillingandpriortoreaming It isbesttoruntheboringtoolthroughtheholeusingafinefeedtothecarriageifyouhave the feedoptiononyour latheThe final finishingcutshouldbeputthroughtwoorthreetimesatthesamesettingtoeliminateanyspringinthetoolworkorlatheIftheholehasanintermittentcutthroughitsuchasacrossholetheholeisbestboredtosizeIt ispossible toborequite smallholes if youhave the right

tool Commercial lsquosmall holersquo boring tools are very expensivebut Ibuythemsecond-handwhenever Iseethemso Iusuallyhave a stock It is easy if time consuming to grind up smallboringbarsbuttheyareveryusefulespeciallywhenyouneedtotrueupasmallholepriortotappingorreamingEndmillsandslotdrillsmakeusefulboringtoolsAs longas

yougetthecuttingedgeoncentreheighttheywillboreaswellasaproperboringbarespeciallyinaluminiumYoucanmakesimplehome-madeboringtoolsbydrillingand

reamingaholetotakeaHSStoolbitintoasteelshankIdeallythe shank should be made of high tensile material or silversteelThetoolbitshouldbesecuredwithahightensilesocket-headedgrub screwor similar The tool bit caneitherprotrudefromthesideoftheboringbarforthroughholesorprotrudeatthe frontof theshankat45degrees ifyouareboringablindholeRoundboringbarscaneitherbeclampedintotheVeegroove

foundinsometoolholdersorheldinasplitsquareshankEithermethodissuitableespeciallyastheshankcanbeslidinoroutofthetoolholdertominimizeprotrusionSpeciallyshapedtoolbitscanbeusedtoundercuttheendof

the borewhen it needs to be screwcut and canrsquot be cut rightthrough Inserted HSS boring bars can also be ground up forundercuttingbeforescrewcuttingThereareseveralmethodsofcheckingaboreforaccuracyIf

youhavetoboretheholetofitanexistingcomponentperhapsaballraceyoucanuse theexistingcomponentasagaugeorturnupagaugeRoughout theborewithina few thouof thefinishedsize taking twoor threespringcutsUsea telescopicgaugeapairofcalliperswithamicrometeroradigitalverniertomeasuretheholeBorethestartoftheholebynomorethanonethouata timedonotgoright throughtheboreTest thefrontoftheboreifthegaugedoesnotgointotheborerunthetool right throughunderpower feedBoreout the frontof theholebyanotherthouchecktheboreandrepeatuntilthegaugejustgoesintothestartoftheholeFinishtheboreatthesamesetting checking that the gauge just enters Take a couple ofspringcutstoensuretheboreisparallelYoushouldnowhaveanaccuratelysizedholeThe trick to boring is to finish with very fine cuts Many

engineersdonotrecommendfinecutsbutIhaveneverhadaproblemaslongasthetoolissharp

Asetoftelescopicgaugesforcheckingaboreusedinconjunctionwithamicrometer

Checkingaborewithahome-madegaugeTheleadinisonethousmallerthantheborerequired

USINGABORINGHEADINTHELATHE

AnothermethodofboringacomponentinthelatheistoboltitdowntothecrossslideWhentheworkpieceisbolteddownandtheholeposition is linedupwith theheadstock youcanboretheholeintheworkpieceinseveralwaysFirst however you might need to put a hole into the

workpiece to clear the centre of the hole out of theway Youcandothisbyusingadrillinathree-orfour-jawchuck(smallerdrillscouldbeusedinadrillchuck)Startwithasmalldrillandworkupalmosttothefinishedsizeoftheholetobebored

Boringaholereadyforreaming

Toboretheholethefirstoptionistoholdaboringbarinthethree-jaw chuck This is a good basic method of boring aworkpieceonthecrossslideTheonlyawkwardbitisadjustingtheboringbarsothatasizeholeisboredThisisusuallydonebyanadjustingscrewpressingontothebackofthetipoppositethe cutting edge The tip itself is usually clamped by a grubscrewthroughthesideoftheboringbarHoweveryoucanuseaboringbarthatisafewthouundertherequiredsizeandfinishoffwithareamerA similar way that is easier to adjust is to use the same

boringbar in the independent four-jawchuckThen insteadofadjusting the tip in the boring bar you can adjust the entireboringbar inthefour-jawchuckThisasyoucanimaginewillbealoteasierthantryingtoadjustthetipintheboringbarThethirdmethodofboringworkonthecrossslideistousea

properboringheadThis iseasy toadjustas it isdesigned forthisverypurposeFinallyyoucouldusea lsquobetweencentresrsquoboringbarwhich

isheldbetweentheheadstockandtailstockcentresThisistheonly option when you are doing a long bore such as a largecylindercastingforalocomotiveortractionengine

Boringtheholeusingthefour-jawchuckmethod

Usingtheboringheadinthelathemandrel

Unlike when you are facing and boring a component in achuck you will not be able to face across the front of thecomponent (Boring heads with the ability to face across theworkareavailablebutareunlikelytobefoundintheamateurrsquosworkshop) Thismeans you will have to face across the workwith a flycutter in order to keep the face true with the boreFlycutters are available quite cheaply or you couldmake yourownandholditinthefour-jawchuck

Aflycuttersuitableforfacingthefrontofacomponentthathaspreviouslybeenboredonthe

crossslide

11KnurlingRadiusTurningandProductionMethods

This chapter explains how to use knurling tools and radiusturningtoolsaswellasusingbasicproductionmethods

KNURLING

Knurlingistheprocessofformingorimpressingapatternonapiece of metal often for the purpose of making a grip for apieceofequipmentsuchasaknobBothstraightanddiamondknurlscanbeproduceddependingonthetypeofknurlyouareusing Diamond knurling is usually done with two knurlingwheelsalthoughsingle-wheeldiamondknurlsareavailableKnurls are also available in fine medium and coarse sizes

although the size is relative fromdifferentmakers The speedfor knurling is usually about half of the turning speed for thesame diameter bar Normal knurling is of the male patternwheretheknurlingconsistsofraisedpyramidsFemaleknurlingismuchrarerandconsistsofdepressedpyramidsThere are threemain types of knurling tool but only two of

these are found in the average workshop The first type ofknurling tool is the so-called lsquocutrsquo knurling toolwhichactuallycutsaknurlratherthanpressestheknurlintotheworkThisisaspecialized tool more often used in industry and is veryexpensivesoitisnotfoundinmanyhomeworkshops

lsquoBumprsquoKnurling

The most common knurl is the single-or double-wheel knurlsometimes called a lsquobumprsquo knurling tool The wheels aremountedat the frontof the tool This typeof knurl is pressedintotheworkbyusingthecrossslideandcanproduceagoodqualityknurlHowever itdoesputveryheavypressureonthemandrelandlathebearings

Acommerciallyavailablestraddleknurlingtool

StraddleKnurling

Thebest typeofknurl foroccasionaluse is thestraddleknurlwhich has two knurling wheels that completely straddle theworkpieceThistypeofknurldoesnotputastrainonthelathebearings and so is preferred bymost lathe users (Two-wheelknurlingtoolsareavailablethatresemblestraddleknurlingtoolsbut they donrsquot open up to take anything more than smalldiameters relying on pressure at the side of the job like alsquobumprsquoknurl)To set the straddle knurl up wind the tool against a bit of

plateheldontothesideofthebarRemovetheplateandmovethetoolinbythethicknessoftheplatehalftheknurldiameterandhalfthebardiameterThiswillputthetoolontothecentrelineofthebar

Settingtheknurlingtool

In use set the knurling wheels to the centre as describedabove wind the knurls onto the outside diameter of the barwindtheknurlawayfromthebarandmovetheknurlingwheelsclosertogetherbytwicethedepthoftheknurlpatternSwitchthelatheonandwindthetoolbackontothecentrelineandthetool should start to form the knurl You can now traverse theknurlingtoolalongtheworkpieceto formtheknurl remembertousecuttingoilNote that theknurlsshouldhavechamferedsidesifyouaretraversingalongtheworkpieceYouneedtogodeepenoughsotheknurlisfullyformedbut

notsodeepastodeformtheknurlBecausetheknurlstraddlestheworktheknurlsstartoff independentlyandmaynotbe inalignment around the diameter Once you start moving theknurlingtoolbackwardsandforwardsalongtheworkhoweverthetoolshouldlineitselfupThismeansyoumayhavetoturndownorpartoffthebarwhereyoustartedtheknurlIfyougotoodeepespeciallyinaluminiumthewholedepth

ofknurlcouldgetdestroyedandevendropoff theparentbarThis is called flakingKnurling isnotadifficultprocessa littlepracticewillsoonhaveyouknurlinglikeaprofessionalengineer

Anaccomplishedbitofknurling

AformtoolcuttingaballTheinsetviewshowstheformtoolandafinishedball

RADIUSTURNING

Sometimesweneedtoformanexternalradiusontheendofabit of bar perhaps for a ball-shaped handle We can use asimple lathe attachment to do this Basically the attachment

consists of a short turning tool mounted onto a U-shapedcomponent that is arranged to pivot on another U-shapedcomponentheldinthelathetoolpostBy pivoting the attachment back and forth a radiuswill be

generatedForatrueradiusthepivotpointshouldbesetonthecentrelineofthebarTheradiusgeneratedwilldependonhowfarthetoolbitissetbackfromthecentrelineoftheworkpieceTosetthetoolupwindtheattachmentuptoaplateheldto

the sideof thebar youareworkingon remove theplate andwindinthewidthoftheplatehalfthewidthofthebarandthewidthofthefixturetothecentrelineofthepinThiswillputthepivotonthecentrelineThenyoucansetthetooltotheoutsidediameterofthebarThiswillproduceaballthesamediameterasthebarTo turnan internaldiameteruse the samemethodbut the

turning tool will need to pass through the centre of the pivotand out the other side You will be limited to shallowdepressionsratherthanlargesemicirclesbutthistechniquecanstillbeusefulonoccasionThealternativemethodof formingaball iswithaball form

tool

Astopbarblockforthecarriagestop

PRODUCTIONMETHODS

PRODUCTIONMETHODS

Foreaseofproductionthefirstthingyouneedtouseisabedstop (see Chapter 5) The chances are that you will need tomakeyourownTheoneIuseisveryversatileandconsistsofablockmountedatthefrontofthelatheheadstocktogetherwitharodtoactasthestopDependinguponwhatyouaredoingitmaybeusefultohave

morethanonestopbareachwithitsownseparatestopblockInusethebarisinsertedintothemainblockasfarasthestopblock(if fitted)andlockedinplaceThefirststopbarcouldbeusedto facetheworkpieceandthesecond(shorterbar)couldbe used to turn along the diameter while a third bar couldpositionthepartingofftoolAnalternativeadditiontothestopbarcouldbeawasher(orwashers)ofknownthicknessplacingthewasher(orwashers)onthebarwillextendthestoppositionbythethicknessofthewashersusedAusefultipistostampanumberonthestopblockssothat

eachone isnumberedYoucouldalso stamp the thicknessonthewasherssoyoudonrsquothavetokeepmeasuringthemandjustpickthemupinthecorrectorderItsavesalittletimeandhelpsavoiderrorsThe whole point about using a stop is the consistency of

positionwhichistransferredtotheaccuracyofthecomponentit gives Once you have learnt to use a stop youwill wonderhowyoumanagedwithoutitEvenforone-offcomponentsitwillsaveyoutimeForatypicalone-offsteppedshaftsetthestopsotheturning

tooljustfacesthebarandfaceoffMove the top slide along for the length of the turned step

requiredTurnthestepYounowhaveastepontheendofthebarofaknownlengthNofiddlingnomeasuringndashyouknowitiscorrectUsing the bed stop offers a simple way of doing repeat

turning of lengths and diameters in the lathe Stops are notlimited to production methods they are very useful formachiningone-offsaswell

A single stop bar will serve for much of the work you aredoingbutsometimesyouneedmorethanonestopTheanswerhereistousemorethanonestopbarinconjunctionwithastopblockEachbarhasitsownstopblockthatcanbetightenedupThenyoucaninterchangethestopbarsandeachbarcanbesettotherequiredlengthbyusingavernierorruleYoujustsetthetwostopblockstothedifferencerequiredandlockthestopbarintheholderasnormalWhenyouneedmorethanoneofeachitemitisveryeasyto

save time in theworkshop once the lathe is set up you canmake several items in quick succession A typical example ofthis type of production is a simple spacer Set a facing andchamferingtoolinonetoolholderapartingofftoolinanothertoolholderandadrillinthetailstockchuckThefacingtoolandparting off tool are in fixed positions to each other so it is asimplematter of drilling thehole facingoffwithone tool andparting off with the other As long as the gap between thepartingofftoolandthefacingtoolremainsconstantthespacerswill remain at the samewidth each time youmachine one ofthemTheeasywaytosetthethicknessofthewasheristofaceoff

theendofthebarbringthepartingofftooluptothefinishedface and lock the cross slide Wind the parting off tool backslightly so you can move the bar forward in the chuckMeasuring with the vernier calliperrsquos depth rod from therighthandfaceofthepartingofftoolbringthebaroutslightlylonger than is needed for the washer thickness Using thetailstock chuck drill the hole using a centre drill for the firstwashertoensurethedrill runstrueNowsetthefacingtool inpositionfaceoffthewasherandpartofffromthebarMeasurethe washer and adjust the facing tool either way so that thethicknessof thewasher iscorrectPull thebar fromthechuckslightlyfurtherthanthefacingtoolsothateachwashercanbefaced to lengthYoucanmakeasmanywashersasyouneedall of the same thickness The same applies to nuts and anyothercomponentthatneedstobeasetlengthIfmakingboltsor screws theprinciple is thesamebutyou

willneed to turndown thediameter tobe threadedThis timethedifferencebetweenthepartingofftoolandtheturningtoolisthethicknessoftheheadInordertofacetolengthhoweverawasher of a known sizemust be inserted between the stopblockandthecrossslideThiswasherwillbethelengthoftheturneddownportionofthecomponentIfyouwanttomakeabatchofcomponentsbutdonrsquotwantto

keepmovingorchangingtoolsyoucanmachinethebatchonestepata timedoingoneoperationoneachcomponentbeforedoing the next operation on all the components Repeat thisuntil the complete batch ends up as completed componentsYou have the added advantage that the components willprobablyallbethesameshapeandsizesomethingthatisnotalwayspossiblewhenmachiningeachcomponentindividuallyTo make a batch of components such as washers to the

samethicknessisquitesimpleSetupapartingtooltopartoffthe components and set up a facing tool to face thecomponentsThedifferenceinpositionbetweenthefacingtooland the parting toolwill be the thickness of thewashers Youcanadjustthethicknessofthewasherbymovingthefacingtoolbackwardsor forwardswith the topslide toadjust it The rearpartingofftooldoesnotmoveotherthantopartoffthewasher

Makingwasherstothesamelengthusingfixedpositiontools

TAILSTOCKTURRET

AnotherusefulaccessoryisthetailstockturretThisisarotatingheadthatisusuallysetbackatanangleItfitsintothetailstockof the lathe and has multiple stations to take different toolsoftenitwilltakefourfiveorsixtoolsThebenefitofthisisthatitcanhaveabarendstopacentredrilladrillacountersinkatapandadieoranycombinationthereofallsetupreadytousein sequence The tools normally fit into holes bored into theturretToavoidtoolsstickingouttoofar it isbesttousestubdrillsinsertedintoroundbarsthatfitintotheturret

Anindexingturretthatfitsdirectlyintothetailstockofthelathe

YoucaneitherdrillandtaptheroundbarsoruseLoctite tosecure the drill in the round bar You can also buy roundadaptorswithaJacobschucktapermachinedontheendtotakechucksAnothermethodoffittingchucksistodrillandtaptheround bar to take chucks with threaded extensions ThesechuckscanoftenberetrievedfrombrokenBlackampDeckertypedrillsDieholderscanslideonapieceofroundrodintheturretFor

smaller diameter threads you can stop the die from rotatingusing your hand There is no need to reverse the lathe whenthreading just stop it and spin the die off by hand the samegoes for taps For larger taps and dies you can use a shorttommybartostoprotationbutmakesurethatthetommybarpositionisclosertotheworkthantheendofanyofthedrillsorthetommybarwillsnapthedrillsifyouletgoofitorifthetapordiejamsupYoucanalsomakeorbuyarunningcentretofitintotheturrettosaveremovingitwhenyouneedtousealathecentreOnlydothiswithsmallorlightworknotheavybarsorfor largecutsWhenused inconjunctionwithagoodbedstop

system a tailstock turret becomes a very versatile productionfacilityTheturretcanbemademoreversatilebyfittingalever-feed

tailstockattachmentoracapstan-style feedattachmenttothetailstockturretEitheroftheseattachmentswillmaketheturretveryfastinoperation

Anindexingturretsetupwithastopandacentredrill

Standardlever-feedtailstock

SECONDOPERATIONWORK

SECONDOPERATIONWORK

Sometimes it is necessary to do second operation work on apart-machinedcomponentUsually thiswillbeon theoppositeend to the one already turned There are two main ways ofholding theworkpiece in the correct position for furtherworkthechuckbackstopandsoftchuckjawsThechuckbackstopisquitesimpletomakeItconsistsofa

draw-incolletapieceofplainbarforthestopabitofthreadedbar a nut and a top hat collar The collet goes into the lathemandrelandisdrawninbythethreadedbarThethreadedbargoesthroughthemandrelandislockedinplacebythenutandthe tophatcollarat the left-handendThe tophatcollar is toprotecttheendofthemandrelThestopbarfitsthecolletandispositionedsothattheworkislocatedattherightdepthinthechuckThismeansthateachcomponentput intothechuckupagainstthebackstopwillalwaysbeheldinthesameposition

Capstan-stylelever-feedtailstock

Adraw-inbackstop

Softjawswithhexagonsadded

The secondmethod is to hold the component in soft jawswhich are bored out to hold the component (see Chapter 5)ThismeansthecomponentshouldrundeadtrueandeachonewillbeheldinthesamepositionreadytobemachinedSoft jaws tend to be used for larger components while the

backstop ismore likely tobeused forbarworkYoucanboltextension pieces to soft jaws to hold larger diameters orextensions can be machined to make a nest to take largercomponentsWhensoft jawsarewornoutandfaceddowntoo

lowforfurtheruseyoucanboltapieceofhexagonbartoeachjawtogivethemanewleaseoflifeIfyouhaveabatchofthreadedcomponentstofinishonthe

second end you can screw them into a bit of bar held in thechuck If theyarehexagonbolts just tightenup lightlywithaspanneriftheyareroundheadandtheheadwillbemachinedlateryoucouldtightenanduntightenthemwithapairofpliersThe more production work you do the more varied the

methods you will learn and the quicker you will makecomponentstoahighstandardofaccuracyA sensitive drilling attachment can be very useful when

drillingwith tiny drills The feed is by hand which gives it itssensitivity The attachment can also be used for small tapswherethetravelisfairlyshort

Machiningscrewheadsbyholdingthescrewinathreadedmandrel

Asensitivedrillingattachmentthatfitsintothe

tailstockchuck

ThisVeeattachmentisusedforcrossdrillingandcanbeusedintheheadstockorthetailstockofthelathedependingonthelengthofthebartobecrossdrilled

ThisisarevolvingtaperforthetailstockIfyoufitadrillchucktoityoucanuseitasarunningsupportforsmallbarwhereacentreisnotpermissible

12TapsDiesandScrewcutting

Thischaptershowshowtousetapsanddiestocutinternalandexternal threads in the lathe Italsoexplainshowyoucansetupasimplegeartrainandcutascrewthreadwiththehelpofascrewcuttingdialindicator

Atypicaldie

CUTTINGTHREADS

Threadcuttingeither internalorexternal isan importantpartoflearningtousealatheThepurposeofathreadisusuallysothatyouareabletoholdpartstogetheralthoughotherusesforthreadssuchasleadscrewsandfeedscrewsformachinetoolsareoftencalledfor

Safetyhasalreadybeencoveredindepth(seeChapter2)butafewextrawordsonsafetywhenthreadcuttingarecalledforWhen tapping a hole or threading a bar from the tailstock atailstocktapordieholderisoftenusedForthesmallerthreadstheholdershaveaknurledbodyandrotationcanbestoppedbysimplyholdingthebodyoftheholderinyourhandAslongasyoukeepyourhandawayfromthechuckandany

sharp lathe tools on the cross slide you should be fine (ifpossible remove either the tool holder or the tool itself )Providedthereisnothingtocatchorsquashyourhandonyoucan hold the knurled tap or die holder in your handwhile thelathe is running slowly under power and releasing the holderwhen the full length of the thread is cut or the pressurebecomes too great for you to stop the rotation (By slowly Imeaninveryslowbackgear)For largerthreadshoweveratommybarwilloftenneedto

beusedtostopthetapordieholderfromrotatingWhenusingthe tommy bar to prevent rotation do not under anycircumstances use the lathe under power Instead switch themachinerightoffandunplugit ifpossibleTurnthetapordieholdingthetommybarwiththerighthandandstopthechuckfromrotatingwiththelefthandThere are already many published charts providing thread

data covering such factors as tapping hole sizes minimummaximum and effective diameters as well as pitches andthreadsperinchIwillnotbeprovidingthemherebutwishtopoint out that tapping size drills can vary with the materialbeingcutWhenIamtappingsmallsizes instainlesssteel forexampleIusuallydrillthehole0004in(01mm)largerthanthefigurestated in thechartThisway Iam less likely tobreakatapinthehole

HSSorCarbonSteel

TapsanddiesareusuallymadefromcarbonsteelorHSSHSStapsanddiestendtoremainsharpformuchlongerthancarbonsteeltapsbutcarbonsteelisusuallycheaperNewcarbonsteel

tapsanddieswillprobablybefineforsmallerholesandsoftermaterials but wherever possible HSS should be your firstchoice Second-hand taps and dies are sometimes availablefromtoolshopsoroneBaybutinmyexperiencetheyareoftenbluntandnotworthbotheringwith

Lubricants

Whether tapping threading with a die or screwcutting it isnormallyessentialtousealubricantevenonbrassForbrassaluminium and bronze kerosene (paraffin) or white spirit isgenerallyusedandcanwithadvantagehaveasmallamountofcuttingoiladdedFor steel and stainless steel amodernpaste-based tapping

compound or cutting oil should be used This can also beappliedtocopperthismetalcanbestickybuttakeiteasyandall should gowell I also use paste or cutting oil on cast ironAlthoughmostrecommendationsaretocutcastirondryIhavefoundalubricanttobeveryhelpful

Screwthreadpitchgauge

ThreadGauges

When following a published design you will probably use thethread sizes as recommended by the designer If you are

making a thread to match an existing thread however youneedtofigureoutwhattheexistingthreadisThisiseasiesttodoonanexternalthreadIfyouhaveonlythenuttrytofindaboltthatwillfititandusethattocheckthethreadIfyoucanrsquotfindamatchingboltandtheholeinthenutisbigenoughyoucouldtrypressingabitofplasticineintotheinternalthreadandmeasuringthatTomeasuretheexternalthreadweneedtodeterminethree

thingsusingathreadpitchgauge theoutsidediameterof thethread the pitch of the thread and the thread angle Thesethree checks will probably be sufficient to decide what thethreadactuallyisBritish threads such as British Standard Fine and British

Standard Whitworth and also the Model Engineer threadsystemhaveanangleof55degreesAmerican threads such as UNF (Unified Fine) UNC (Unified

Coarse) UNEF (Unified Extra Fine) ANF (American NationalFine)ANC(AmericanNationalCoarse)are60degreesasisISOmetricUnusually theBritishStandardCycle thread is also60degreesThe other thread youmight come across is the BA (British

Association)threadThishasathreadangleof47frac12degreesandismetricbasedThelargestBAthreadis0BAwhichhasa6mmdiameterwith a 1mmpitch TheBA series godown to 22BAbutinpracticeyouareunlikelytocomeacrossanythingsmallerthanabout14BA

TAPS

TappingistheprocessofcuttinganinternalthreadwithatapFirst a hole is centre drilled and drilled in the workpiece Irecommend that you give the top of the hole a 90-degreecountersinktogivealead-intothetapandalsotostopthetapfromthrowingupaburrontothefaceofthework

Setofhandtaps

TypesofTap

The many types of tap can be divided into hand taps andmachinetapsHandtapsarenormallyheldinatapwrenchbutcan be held in the lathersquos tailstock chuck or a purpose-madetailstocktapholder

Close-upofahandsecondtap

WhentappingbyhandstartthetapuntilitstartstobiteandgiveitanextraturnorsoReversethedirectionofthetapforaturn to break the chip Continue forward for a couple of turnsand then reverseasbeforeContinue todepthor through theworkpiece by continually tapping a couple of turns reversingandcontinuingforwardThisshouldclearthechipsandpreventthetapfrombreakingIfthetapgetshardtoturntakeitrightoutoftheholetoclearanyswarfaddsomemorelubricantandcontinuetappingA set of hand taps will normally comprise a taper tap a

secondtapandaplugtapUsuallyyouwillstartaholewithataper tap This is a tap where the outside of the thread isreducedtowardsthepointbygrindingitonataperThistypeoftap can be used to start the hole but if the hole goes rightthrough the work it may be possible to screw the tap rightthroughtheholesoformingafullthreadrightthroughIfthetapertapistooshortorifyouaretappingablindhole

youneedtofollowthetapertapwiththesecondtapwhichhasmuch lessofa taper In fact itonlytapersrightat thestartofthetapTheplugtapisfinallyusedusuallytofinishoffablindhole

Theplugtaphasnotaperonitjustashortlead-inontheendBetween the three you should be able to tap themajority ofholesintheworkshopWhentappingblindholesitisbesttoworkoutthedepthand

fromtherethenumberofturnsneededforthetaptoreachthebottomoftheholeAsanexamplesaytheholeis9mmdeeptothepointThe tapenters2mminto theholebeforestarting tocutSo9mmless2mmgives7mmThepitchofthetapis05mm7mmdividedby05equals14sothenumberofturnstothebottomoftheholeis14Inpractice12or13turnswillbethemaximumneededWhen tapping blind holes make sure that all swarf is

removedfromthebottomoftheholebeforestartingtotap

Selectionoftapholders

HoldingTaps

TherearetwomaintypesoftapwrenchthehandtapwrenchwhichisdesignedtobeheldwithbothhandsandtheTeetypetapwrenchwhichoncestartedcanoftenbeusedone-handedTapsusuallyhaveeitheracentreholedrilledintheshankor

theshankisgroundtoapointThismeanswecansupportthetapfromthetailstockeitherbyusingalathecentreorbyabitofbarinthetailstockchuckwithafemalecentreinitTeetypetapwrenchesoftenhaveafemalecentreintheendandcanbesupported on a running centreWhen the tap is supported bythe tailstock at one end and the hole in theworkpiece at the

otheritmustbeinlinewiththeholeintheworkpiece

Machinetap

MachineTaps

Themaintwotypesofmachinetaparethespiralpointandthespiral flute The spiral point pushes swarf downwards throughthe hole while the spiral flute pulls the swarf out of the holeSpiralflutetapsaremuchweakerthanspiralpointtapsandintheory should not be used for tapping by hand However inpractice you can often get away with hand tapping using aspiralpointtapifyouareverycarefulIneithercasethetapisdesigned for continuous rotation swarf being automaticallycleared so the regular reversal as with a hand tap is notnecessaryIf you are careful you can probably get away with using a

hand tap under power but only do this with a hand-held tapholderwhereyoucanquicklyletgoifthetapstartstostickYou can also getmachine taps thatwill cut a thread under

powerbyscrewingthroughthejobwithoutstopping

Spiralflutetap

SpeedsforTapping

Tappingspeedsshouldbe low lowbackgearspeedshouldbefineWhenyouhavetappedtheholetodepthorrightthroughtheworkpiecestopthelatheandspinthetapoutbyhandThiswillbequickerthanreversingthelathe

ThreadingfromtheTailstock

For small taps you can use the sensitive drilling attachment(seeChapter11)orifthetapislargeryoucoulduseaslidingtapholderThiscanbeassimpleasachuckmountedonataperat one endwith a parallel hole through the chuck shank ThechuckthenslidesonabarheldinthemaintailstockchuckForlargetapsyoucanuseatommybartostopthetapholderfromturningbutthetommybarshouldnotbesolongastofoulthelathebedoranyotherpartofthemachineifyouhavetoletgoInfactitisfarsaferifyoudonotusethetommybartothreadunderpower

DIES

Dies also come in carbon steel andHSS versions The outsidediameterofadieoftenvarieswiththesizeofthethreadbeingcutalthoughthediameterwillbetooneofasetstandardDiesusually have themakerrsquos name and the thread details on thefrontof thedieThis is theside that ispresented to theworkThediewill havea short lead-in if this isnot requiredon thefinishedthreadyoucanreversethedieanditwillcleanuptoashoulder

SlidingtapholderSlidingdieholdersarealsoavailable

When cutting a thread especially a small one it pays tomaketheinitiallengthofthreadlongerthanthatrequiredThisissoyouhaveabitat thefronttoplaywithtogetthethreadright Then you can part off the excess length leaving a goodthreadoftherequiredlengthDies are usually split so you can adjust them to cut a size

threadIdeallyyoushouldhaveadieholderforeachdiesoyoucansetthedietocutsizewithouthavingtoresetiteverytimeyouchangethedieThedieshouldbesetsothatitcutsasizethreadinonepassDie nuts are often hexagonal in shape They are used to

cleanupanexistingthreadthat isdamagednot tocutanewthreadfromscratchFor each thread you are going to cut you should make a

home-madegaugetappedwithyourowntapWhenyoucutthethreadanditfitsthisgaugeyoushouldthenhaveagoodbutnottightorloosethreadYoushoulduseatailstockdieholderwithaslidingbodywhen

threadingfromthetailstockasthiswillholdthedietruetothethreadIdeally the tailstock die holder should be knurled and also

haveatommybarholeforeaseofuseThe speed for threading with a die in the lathe should be

quitelowamaximumof60rpmshouldbefineformostjobs

SCREWCUTTINGATHREAD

Whilecuttingathreadwithtapsanddiesisperfectlyadequatefor most applications the ability to cut an accurate screwthreadbyusingthelatheisaveryusefulfacilitytohaveIfthethread is large or non-standard taps and dies may not beavailable or they may be so expensive as to be out of thequestionforuseintheamateurrsquosworkshopVariouspitchesofthreadcanbecutbythesimpleexpedient

of changing the configuration of the change gears or alteringtheleversonthescrewcuttinggearboxifoneisfittedWewillconcentrate on a lathe with change gears if you have ascrewcutting gearbox please refer to the manufacturerrsquoshandbookMost lathes that youwill comeacross are likely to have an

imperialpitch leadscrewThiswillbeapitchofsomany teethper inch (TPI) Typically this will be 4 or 8 TPI although otherpitchesareavailableForourexamplewewillbeusingalathewithan8TPI leadscrewandasetofchangewheelscomprisingthefollowingnumbersofteeth2times202530353840455055606570and75

SETTINGUPTHECHANGEGEARS

Letrsquostakeatypicalthreadpitchof20TPIForeveryturnofthemandrel the leadscrew needs to move forward 120in Thismeans we have to set the change gears so the mandrel toleadscrewturnratio iscorrect Inpracticethemandrelgear islikely tobe20 teethand this is unlikely to change nomatterwhat thread we are cutting This means we will change theleadscrew gear which has to have the correct ratio to themandrelTheTPIwewishtocutis20usingaleadscrewwithapitchof

8TPI20dividedby8givesusaratioof251Thismeansthatthe mandrel gear needs to rotate at 25 times the leadscrewgearAsthemandrelhas20teeththeleadscrewgearneedstobe25times20teethwhichisa50toothgearInpracticea20toothgearanda50toothgearmaybetoosmalltotransferthedrive from the mandrel to the leadscrew and intermediategear(s)willneedtobeusedThese gears are called idler gears and they can have any

number of teeth Youmay think these idler gears change theratio of the mandrel to the leadscrew but they do not Theysimply transfer the drive from the mandrel gear to theleadscrew and the ratio stays the same This concept can behardtograspsoIwilltrytoexplainitsimplySay the mandrel gear does one turn This makes the idler

gearorgearsmoveexactly20teethandthisinturnmovestheleadscrewgearexactly20teethAsyoucanseetheratiodoesnotaltertheleadscrewgearmoves20teethforevery20teeththemandrelgearmovesandtheratiostaysthesameThistypeofset-upisknownasasimplegeartrain

Simplegeartrain

Compoundgeartrain

Letuslookatanothercommonthreadpitch32TPITheratioofleadscrewtoTPIis41(8times4=32)Sotheleadscrewgearneeds to be themandrel gear 20 teeth times 4 = 80 teethLookingattheavailablegearswedonrsquothavean80toothgearThismeanswewillhavetouseadifferentmethodtogetour41ratioWithamandrelgearof20teethwecouldusea40toothto

give us a ratio of 21 We are now halfway there but needanotherpairofgearswitha21ratioWedohavea30anda60

toothgearsothiswouldgiveusoursecond21ratioWecouldnot set these gears up as in the previous example howeversince the two intermediate gears would just act as idlers andtheratiowouldbe2150percentoutfromwhatisrequiredWhatwewouldhavetodoismountthe40toothandthe30

tooth gears on the same spindle so they rotate at the samespeedaseachother(The20toothgearmustdrivethe40toothgearandthe30toothgearmustdrivethe60toothgearinthisorder)Thiswouldgiveusthecorrect41ratiothatweneedAswehavemountedtwogearsononespindlethisisknownasasinglecompoundgeartrainDependingonyourlatheyoumayneedanidlergearbetweenthe30toothgearandthe60toothgearAgainthiswillnotalterthegearratiosYou can also have double compoundgear trainswhere two

lots of gears are mounted together on two spindles This istaking us into complicated territory however and I will referreaders to the screwcutting chart provided for their particularlathe Ifyour lathedoesnotcomewithascrewcuttingchartasearchon the Internet should findone that you candownloadandprintoutThemost likely application of double compound gear trains

would be to cutmetric threads with an imperial leadscrew orimperialthreadsover60TPII have tried to keep this explanation of setting up

screwcutting gears simple and the maths to a minimum Theexplanationgiventogetherwiththescrewcuttingchartforyourlatheshouldbemorethansufficienttogetyougoing

ExternalscrewthreadtoolmadefromaCoventry

diechaser

CUTTINGTHETHREAD

The speed for screwcutting should be about mid-back gear ifyouhaveitpreferablysomewherearound30ndash40rpmatmostTherearetwomainmethodsofscrewcuttinginthelatheThe

firstoneinvolvesthetopslidesetparalleltotheworkandintheothermethodthetopslideissetonanangletothework

Externalsinglepointscrewthreadtoolsettinggauge

Cuttinga20TPIThreadwiththeTopSlideParallel

For a 20 TPI Whitworth thread the pitch is 0050in and thethreaddepthisaconstant064ofthepitchsothethreaddepthis 0050 times 064 = 0032in This is the depth the cross slideshouldbewoundinWhilethedepthofthreadis0032inyoualsoneedtomove

the top slide forwardat eachpass Fora standardVee threadthisneedstobehalfthein-feedofthescrewcuttingtoolsoyoumovethecrossslideinby0010inandmovethetopslidealongbyhalfthis0005in

Cuttingascrewthreadwiththetopslidesetparalleltothelathe

Cuttingascrewthreadwiththetopslidesetatanangletothelathe

Theendresulta20TPIfinishedthreadbeforetidyinguptheendandundercutting

Cuttinga20TPIThreadwiththeTopSlideatanAngle

This angle will vary according to the thread being cut but itshouldbeabout1degree less thanhalf the includedangleofthethreadforaWhitworththreadof55degreesforexampletheangleshouldbehalfof55degreesminus1degreegiving265degreesNotethattheangleistakenwiththetopslidesetat90degreestotheworkWiththetopslidehandlefacingyou(at90degreestohowit isnormallyused)rotatethetopslidethe required number of degrees (265) to the right Beginnersoften rotate the top slide 265 degrees to the left from thenormalpositionwhichwouldgivean included threadangleof127degreesThisisclearlywrongBecausethetopslideissetonanangleyouwillneedtofeed

thetopslideinfurtherthanifthetopslideissetparalleltothelatheYoucan findthe increaseddepthof threadbyusingthefollowingformula

c=bcosineofA

whereAistheanglecalculatedathalftheincludedthreadangleminus1degreegiving265degreesb is thedepthof thread(forWhitworththreadsthisis064timesthepitch)andcisthecalculatedangulardepthofthreadFor a 20 TPIWhitworth thread the pitch is 0050in and the

threaddepthisaconstant064ofthepitchsothethreaddepthis0050times064=0032inThecompensateddepthofthreadisthen0032individedbythecosineof265degrees=00357

UsingtheThreadCuttingIndicator

With an 8 TPI leadscrew if the thread being cut has an evennumber of threads the leadscrew can be engaged at anypositionof the threadcuttingdial indicator If the thread isanoddnumberyoushouldusethesamenumberoranyalternatenumberthatisoneorthreetwoorfourForthreadswithahalfpitch always use the same number For metric threads orpeculiar numbers do not disengage the clasp nuts withdrawthescrewcuttingtoolandreversethemotoruntilthetoolgoesback to the start If the thread is an exact multiple of theleadscrewtheclaspnutscanbeengagedatanypositionIfindoubtalwaysengageatthesamenumberoneIttakes

verylittletimetotraversetheextradistancerequiredFor leadscrews other than 8 TPI please refer to your lathe

manual

AcknowledgementsandUsefulContacts

I would like to thankMy TimeMedia Ltd (Publishers ofModelEngineer and Model Engineersrsquo Workshop) Ken Wilson TonyJeffreeandTranswavePowerCapacitorsLtdfortheuseoftheirphotographs

USEFULCONTACTS

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CowellsSmallMachineToolsLtdTendringRoadLittleBentleyColchesterEssexCO78SH

willlookatselectingsuitablespeedsandfeedsChapter 4 dealswith sharpening lathe tools andhow to set

themupinthelatheChapter 5 covers the different types of chucks how to use

themandsetworkupaccuratelyinthemChapter 6 teaches you basic turning between centres and

then introduces turning with the work mounted on the lathefaceplateChapter7isaboutholdingworkinacolletandhowyoucan

make and use several different types of mandrel forworkholdingChapter 8 explains how to turn a taper using the top slide

theuseoffixedandtravellingsteadiesandmakingaformtoolChapter9explainshowtousedrillsandreamersinthelathe

includinghowtoselectthecorrectspeedsandfeedsChapter 10 shows the different ways to bore holes in the

lathewiththeworkheldinachuckmountedonthefaceplateorheldonthecrossslideChapter 11 explains how to use knurling tools and radius

turning tools as well as making simple form tools and basicproductionmethodsChapter 12 shows you how to use taps and dies to cut

internalandexternal threads in the lathe Italsoexplainshowto set upa simplegear train and cut a screw threadwith thehelpofascrewcuttingdialindicator

1BuyingYourFirstLathe

WHATSIZEOFLATHEDOIREQUIRE

ThefirstthingtoconsiderwhenbuyingalatheisthesizeoftheworkthatyouwanttodoWhatisthelargestdiameteryouwillwanttoturnonitandwhatisthelongestlengthyouwillneedtoturnA3frac12times18in(90times457mm)lathewillallowamaximumdiameterof7in (178mm) tobe turnedover the lathebed thelatterfigureisknownastheswingInpracticethoughthisisatheoreticalmaximumas it is stillnecessary toholdandclampthe article being turned The swing over the cross slide isusuallymuchsmallertypically2in(50mm)Many lathes however aremanufacturedwith a gapbed at

the headstock end to enable short items of a large diametersuchaslocomotiveortractionenginewheelstobeturnedLathes are also sometimes available as standard and long

bed lathes The long bed lathe as the name suggests allowslongermaterial to be turned within the capacity of the latheWhen turning longermaterial the diameter will be limited bytheswingoverthecrossslideThiswillbealotsmallerthantheswingoverthebedIfbuildingamodelsuchasatractionengineoralocomotive

the deciding factor for the size of lathe is likely to be thediameterof the largestpairofwheels thatneed tobe turnedBefore deciding on the size of lathe required you shoulddetermine the size of the largest diameter and the longestlength of material that needs to be turned Another factor indeterminingwhat lathe tobuy is theavailabilityof sparesand

accessoriesisthecompanystilltradingwillitstillbetradinginthe future and are there large amounts of secondhand partsandaccessoriesavailablefromtooldealersoroneBay

Atypicalinvertertoconvert240voltssinglephaseto240volts3phase

LATHEELECTRICS

Single phase electric is where the lathe plugs into the mainssupplyinyourhouseThemotorwillhavetheusualliveneutraland earth leads Lathes supplied for factory use usually havethree phase motors and require three live wires each of adifferentphaseThinkofaphaseasan incomingwaveon theseashore three successive waves make up the three phasesneededEachphaseisthesameastheprecedingonebuttheyareoutofsyncandallpeakatadifferenttime

Aforwardreversecontrolboxforaninverter

Convertersandinverters

Youcan runsome3phasemotors fromasinglephasesupplyviaaconverteroraninverterThemotor informationplatewillusuallysay240volts440voltsif it iscapableofrunningonaninverter Inside the motor there will be changeover tags tochange the motor from 440V down to 240V Follow theconverterinverter manufacturerrsquos instructions for furtherinformation It isnotusuallyverycomplicatedto runa240V3phasemotor from an inverter and thiswill give a quieter andsmoother running motor than a single phase supply canprovide This usually requires some simple programmingexplainedintheinverterrsquosinstructionsanditusuallytakesfiveminutestogetthemotorworkingproperly

ThismotorispartoftheinverterpackageshowninthepreviousillustrationNowiringisinvolvedasthemotorleadplugsstraightintotheinverterbox

Theinverterrunsataconstantvoltagebutthespeedofthemotor will change as the frequency is raised or lowered Isuggest limitingyour inverter from full speed tohalf speed sothatthefanstillcoolsthemotorandstopsitfromoverheatingyoucanthenusethebeltstochangethemainspeedstepsasusual(Ifyoumustuseveryslowrunningitispossibletoaddaseparatefansuchasacomputercoolingfantogiveconstantairflow) Most inverter suppliers offer a forwardreverse andspeedcontrolboxthatcanbesetupinaconvenientpositiononthe machine These are well worth fitting for convenience inuse

Thisinverterisdesignedformountingonthefrontofthelathe

While inverters are designed to run only onemachine youcangetconverterstopowermorethanonemachineatatimeDependingonthesizeandpoweroutputconverterscostaboutthreetofourtimesasmuchasaninverterTherearetwomaintypesofconverterRotaryconvertersare

designedtorunmorethanonemotoratatimeThisis ideal ifyouwanttorunmorethanonemachineortwomotorsononemachineforexamplethemainmachinemotorandperhapsanauxiliary motor that drives the machinersquos coolant pump orpowerfeedsystem

Arotaryconvertercapableofpoweringmorethanone3phasemotor

ThesecondtypeisthestaticconverterwhichisdesignedtorunonemotoratatimeThereisofcoursenothingtostopyouusingthestaticconverteronmorethanonemachinebyfittingasuitablefemaleelectricalconnectortothestaticconverterandmatchingmaleconnectorstotheindividualmachinesThiswayyoucanconnectthestaticconvertertoonlyonemachineatatime

Thisstaticconverterissuitableforpoweringone3phasemotorIfyoufitasocketontheoutputhoweverdifferentindividualmachinescanbepluggedintoitoneatatime

Theelectricalloadingonrotaryorstaticconvertersmustnotexceed theirmaximumrating If indoubton the loadcapacityneeded to run your machine(s) you should consult the

manufacturerorsupplieroftheconverter

AnearthleakagetripisidealforquicklyeliminatingamotorwheretheelectricalinsulationisbreakingdownItisusefulfordetectingcertainelectricalearthingfaultsbutshouldnotbeusedasaguaranteeofelectricalsafety

Simpleelectricaltestingandsafety

Whenbuyingasmallsinglephasesecondhandlathetakewithyouanearth leakage testerof the typeused for lawnmowersandothergardentoolsIonceboughtaUnimat3lathetookithomeandpluggeditinItkeptblowingtheearthleakagetripinthefuseboxeventhoughithadworkedperfectlyatthesellerrsquoshouseIsolditonatalossbutthebuyerdidknowtherewasaproblemwiththeelectricsIt is most important that the metal parts of any lathe are

connectedtotheearthwirewhichisinturnconnectedtoearthMake sure that themotor frame is also connected toearthassome motors have dampening rubber mounts that insulatethem from themachine itself If in doubt about any aspect ofelectricalinstallationpleaseconsultaqualifiedelectrician

Acontinuousbedisidealwhenworkingwiththefaceplateorwithcollets

LATHEBED

Thelathebedisthebackboneoftheentirelatheandisthepartthat is mounted on the bench or stand There are two maintypesoflathebedtheplainbedandthegapbedTheplainbedisusuallycontinuousallthewayalongitslengthwhilethegapbedhasas itsnamesuggestsagap in thebedThis isnotaliteralgapbutasteppedsectionthatallowsbiggerdiameterstobeturnedthanyouwouldotherwisebeabletoturnonaplainbed latheThisgap isameansofmakinga lathesmaller thanwouldberequiredforaplainlatheabletoturnasimilarsizeof

componentSome continuous lathe beds have a section next to the

headstock that can be removed to increase the diameter thatcanbeturnedThisfeatureisusuallyonlyfittedtolargerlathessuchasaremostlyfoundinfactoriesSome lathes have hardened beds although most are just

plaincast ironTherearethreemaintypesofbedwayscalledshearstheplainflatbedwithsquarewaysabedwithaflattopand a 60 degree dovetail at each side and a bedwith raisedandinvertedVeewaysOnthelastofthesethetailstockusuallyrunsononesetofVeesand thecarriageonadifferent setofVees resulting in lesswear to themain slidesWidebedsarebetterandmoreaccurateasthelathecarriageislesslikelytotwistonawidebed

Close-upviewofatypicallathebedwithagapAgapbedlathehasalargerturningdiametercapacitythantheequivalentsizedcontinuousbedlathe

Someveryearly lathessuchas thosemadebyDrummondhad a round bed Although they worked well there is noadjustmentforwearinthelathebed

TheMyfordrangeoflatheshasasquareformofbed

ThistypeofbedhasaflattopwithaninvertedVeeateachsideTheVeesareusuallysetat60degreesbutcanvarywithdifferentmakers

The Unimat SL lathe was sold for many years and manysecondhandexamplesarestillavailableThismodeldiffersfrommostlathesinthatithastwosteelbarsasabedThisisnotaproblemhoweverastheUnimatisintendedonlyforverysmallandlightweightmodel-makingworkandthereistheadvantagethatthebedcanbereplacedbyfittingnewbarsWhen buying a secondhand lathe it is most important to

checktheconditionofthebedYouneedtomakesurethebedis reasonably free from dings rust and hacksaw marksHacksawmarksneartheheadstockareoftencausedbysawing

offworkwhile it isheld inthechuckdingsareusuallycausedbydroppingthechuckonthelathebedwhenscrewingitonoroffthemandrelAsimplechuckboardplacedonthebedwhilefittingorremovingthechuckwillprotectthebedItisalsoidealfor protecting the bed when filing or hacksawing work in thechuck

AlathebedwithraisedandinvertedVeesThecarriageusuallyslidesononesetofVeesandthetailstockslidesontheother

AmodernChineselathebedwithaninvertedraisedVeeThecarriageandtailstockusuallyslideonthesameVee

Wear ismost commonly found at the headstock end of thelathe as a result of machining many short components andrelatively few long ones Make sure the lathe carriage isproperlyadjustedattheheadstockandthenrunitalongasfaras you can towards the tailstock The carriage should bereasonablyfreebutnotlooseallthewayalongthebed

OldroundbedDrummondlathesarestillavailablesecondhandThisparticularexampleistreadledriven

AflatbedlathewithsquarebedwayssuchasaMyfordcanbe checked for wear on the lathe bed using amicrometer orvernierCheckovertheworkingpartofthelathebedonwhichthe carriage slides rather than the part that is not used forguidance Check both the width and the thickness of the bedwaysThetailstockshouldalsobeagoodslidingfitonanyguiding

surfaces Wear is most likely to be found on the tenon thatslidesbetween thebedwaysAworn tenoncouldprobablybereplacedbutthereisnotmuchyoucandoifthetenonguidesarewornTheonlyway to fixawornbed requiresacompletebedregrindThisislikelytobeexpensivesoitwouldbebettertolookforanunwornlatheDecentunwornlathesareouttheresincemanymodelengineersmayhaveboughtthemnewfortyorfiftyyearsagoandhardlyusedthem

TheUnimatSLisaverypopularsmalllatheItsbedconsistsoftwosteelbarsthatcanbereplacedveryeasilywithsilversteeliftheygetwornormorelikelywhentheygetrusty

Asimplewoodenchuckboardwillprotectthelathebedfromdingsandhacksawmarks

LATHEHEADSTOCK

Theheadstockisthelargecomponentmountedattheleft-handside of the lathe bed It needs to have good bearings An all-gearedheadwillalmostcertainlyhaveballorrollerraceswhilethe older type of lathe for amateurs may well have plainbearings either phosphor bronze or whitemetal These areperfectlyadequatebutyoushouldmakesurethere isnowearinthemSomelathesalsohaveamandrelthatrunsdirectly inbored holes in the cast iron headstock casting Plain bearingswillbeperfectlysatisfactoryas longasadequate lubrication isused

Close-upviewofaMyfordheadstockonanML7RNotethelargebronzebearingatthefrontTheearlierML7latheshadwhitemetalbearingsalthoughtheC7capstanhadbronzebearingsandahardenedlathespindle

Tocheck forwear in the lathersquosbearings fitachuck to themandrelandputadialtestindicatorontopofthechuckGentlytry levering the chuck up and down by using a steel bar orsimilarheldinthechuckYouarelookingforminimalmovementhereespeciallyonaheadstockfittedwithballraces

CheckingthelathebearingsforwearAnymovementupanddownindicateswearinthebearing

The mandrel is mounted in the headstock and is usuallythreaded to take a chuck or faceplate The lathersquos mandrelshould not move back and forth in the bearings If it doeshowever itwillprobablybepossibletoadjust ittocorrectanyendwise movement The mandrel should not be too stiff butshouldturneasilybyhandWhentestingalathemakesuretheheadstockbearingsare

correctlyadjustedsothatwherepossiblethereisnoplaySeta tool up take a trial cut alonga length of bar and check forchatter If you are using a correctly set tool and a suitablespeedchatterisasuresignofwornbearings

Manylatheshaveathree-orfour-stepdrivepulleyasthesecondstageofthedrivechain

POWERDRIVE

Manylatheshaveathree-orfour-steppulleyonthemandreltotake the drive from a similar pulley on the countershaft Thecountershaft is in turn driven from the motor which is oftenmounted at the back of the headstock and completes theintegral drive system that is so popular on most amateursrsquolathes

Thisparticularlathehasatwo-stepmotorpulleyandcountershaftwhichdoublestheavailablespeeds

SpeedchartonthebeltguardofaMyfordML7Rlathe

AfewlatheshaveaclutchfittedasstandardorasanoptionalextraTheclutchsaveshavingtostartandstopthemotorwhileitisrunningThishelpstostopwearandtearonthemotorandelectricalsystemAdifferenttypeofclutchsystemtheTriLevaspeedselector

wasonlyfittedtoMyfordML7orC7lathesThishasthreeleversfor setting threedifferent speedsDependingon the leveryoudepressyougetahighmediumorlowspeedIfyoupressoneof the levers downwhile another is right down the first leverwilldisengagethesecondsostoppingthemandrelfromgoinground If the lathe is switched off and all three handles aredepressed the mandrel is locked preventing rotation This isusefuliffilingorhacksawinginthelathe

TheclutchisnormallymountedinsidethelargecountershaftpulleyItisusuallyoperatedbyaleverattheright-handsideoftheheadstockattachedtoapushrodthatpassesrightthroughthecountershaft

TheMyfordTriLevaattachmentwillonlyfitML7andC7lathesandisnotsuitableforML7RorSuper7lathes

Therehasbeenatrend inrecentyearstodoawaywiththecountershaftandpulleysystemandtoreplacethemotorwithavariable speed one with an electronic controller This isacceptable except that at low revolutions it does not providethe torque that can be obtained from a countershaft systemThereisalsothedisadvantagethatthereisnowaytodrivethelatheifthecontrollercircuitboardfailswhereasyoucanjustfita new one if the belt breaks The board could of course befixed provided that a circuit diagram is available and theelectronic components can be identified Sometimes thecomponents are marked with internal house numbers ratherthan commercially recognized part numbers that can beorderedasareplacementfromacatalogueSomeboardsmighteven have the identification marks removed to make repairsalmostimpossible

ThethreadedendofalathemandrelisdesignedsothatthechuckbackplaterunstrueIfthechuckmountingfaceofthebackplateismachinedinsituthechuckshouldruntrueaswell

CHUCKMOUNTINGSYSTEMS

The threaded lathe mandrel nose is not by itself a suitablelocationforachuckorfaceplatesothenoseisusuallygivenaturned register on which to locate the chuck The chuck isscrewedrightontothemandrelovertheregisterandbuttsuptoaturnedcollartokeepthechuckrunningtrueTheothersideof the mandrel collar butts up against the main headstockbearingwhichusuallyactsasathrustfaceThemandrelisusuallyboredthroughandmachinedtotakea

MorsetapercentreforturningbetweencentresDonotputyourfingerineitherendofthemandreltocleanitwhilethelatheisrunningAneasywaytocleanthetaperintheheadstockiswithabottlebrush often sold in chemists to cleanbabiesrsquo bottlesAnalternativeisasoftfeltshotgunbrushdonotuseonemadefromwire

ThislathehasaplainregisterAccuracyreliesonthelathechuckbeingagoodfitontheregister

There are various systems of chuck mounting in useespeciallyon the larger lathesTheproblemwith thescrew-ontype with a register mentioned above is that the chuck orfaceplatecanunscrewwhenthelatheisrunninginreverseTheonly timeyoushould run this typeofmandrel in reverseveryslowly and without taking a cut is if you need to return thescrewcuttingtooltothestartofthethreadyouarecuttingAlternativespindlenosescanbeaplaindiscwitharegisterto

boltthechuckontooracamlockwherethechuckisheldontightlybyturningstudstolockthechuckontothemandrelTheplain discwith register relies on having chuckswith amatingregistertoworkproperly

AnAmericanstandardCamLockchuckmountingbackplateandCamLockchuckplatefittedtoachuckTheyareusuallyfittedtolargerindustriallathes

TheAmericanDstyleCamLocksystemeithertakesachuckor faceplate directly or it has a backplate that can have aregisterturnedonittosuittherequiredchuckAlthoughmanylathe mandrels with Cam Lock fittings have six holes thematchingchuckorfaceplateoftenhasonlythreelockingpinsThe advantage of both of the last two systems is that they

canberuninreversewithoutthechuckcomingoffthemandrel

Theleadscrewisdrivenfromthemandrelviaageartrain

SCREWCUTTINGGEARS

The left-hand end of the mandrel will often have a gearmountedonittodrivethechangewheelgearsandleadscrewThe mandrel gear usually drives a pair of gears called

tumblergearswhicharemountedona leveratthe leftoftheheadstock The direction of the leadscrew can be changed bybringingeitheroneortheotherintogearbyraisingorloweringaleverThereisusuallyacentralneutralpositionwhereneithergearisinmeshThissaveswearonthelathechangewheelsandleadscrew bearings as well as reducing noise while workingMandrelandtumblergearswillbediscussedfurtherinChapter12whenwesetupascrewcuttinggeartrain

A set of changewheels usually comprises about a dozengearsbutthiscanvarydependingonthemanufacturerThesechangewheels which take the drive from the tumbler gearsdown to the leadscrew are mounted on moveable studs toensurethegearsareinmeshwitheachotherDependingonthenumber of gears in the train the leadscrew will turn eitherclockwiseoranti-clockwiseThedirectionof the leadscrewcanbe reversed using the tumbler gears to enable right-hand orleft-handthreadstobecut

Oftentherearetumblergearsinthegeartrainthatcanreversethedirectionoftheleadscrew

YoucanusuallysetthegearstocutaveryfinepitchsothattheleadscrewactsasaselffeedwhenturningfromthesaddleIf you anticipate the need to do any screwcutting check thatthesuppliedscrewcuttinggearswilldotherangeofpitchesyourequire It has been known for certain lathes to be unable tohandle somecommonpitches a typical examplebeing26TPI(teeth per inch) A pitch of 26 TPI is often needed to repairmotorcycles and bikes made before the introduction ofmetrication

MakesurethatafullsetofchangegearsisincludedwiththelatheIfnottheyarereadilyavailablesecondhand

LEADSCREW

The leadscrew ismounted at the front of the lathe there areusuallybearings to support the leadscrewateitherendof thelathe bed It is used tomove the lathe saddle along the bedeither for a self acting feed or for screwcutting Some lathesalso have a graduated handwheel mounted at the right-handendoftheleadscrewforturningthemandrelbyhandSome of the larger lathes also have a separate feed shaft

whichisusuallyaplainroundshaftwithakeywaycutalongittodrivethesaddleusingafinefeedThissaveswearandtearontheleadscrewwhichisthenonlyusedforscrewcutting

Mostleadscrewscanhaveagraduatedhandwheelmountedontheright-handendoftheleadscrew

SCREWCUTTINGFACILITIES

Ausefulfeatureonanylatheistheabilitytocutscrewthreadsof different pitches Leadscrews come in different pitches acommon one being 8 TPI but many variations are fitted todifferent lathes including leadscrews with a metric pitch It isawkward tomachinemetricscrewswithan imperial leadscrewandviceversaSometimesmetricconversionsetsareavailablebuttheycanbehardtofindareusuallyexpensiveandrequirethe lathe to be changed over often using 127 tooth gearwheels This figure is derived from multiplying the metricequivalentof1in(254mm)byfivea127toothwheelisthusadirectconversiontoametricthreadonalathewithanimperialleadscrewA127 toothgear isusuallyvery large if itmatchesthepitchoftheremainingscrewcuttinggearsbutyoucouldusesmallergearswitha smallerDP (diametralpitch)but stillwith127 teeth Youwould also need amatching gear of say fiftyteethtogiveyoua2541ratio

Thislathehasbothaleadscrewforscrewcuttingandadriveshaftforthesaddleandcrossslidefeeds

Ascrewcuttingdialindicatorusuallymountedtotherightofthe carriage is a useful feature This is a small dial withdivisionsmarkedonitmountedonashaftTheotherendoftheshafthasagearthatmesheswiththeleadscrewandmakesthedial go roundWhen the clasp nuts are engaged the carriagemoves and as the gear moves at the same speed as thecarriagethedialstopsgoingroundWhen you engage the clasp nuts on the leadscrew the

positionwhereyouengagedependsonthepitchofthethreadbeing cut Some thread pitches allow you to engage at anydivision of the dial while others need to be engaged at aparticularpositionof thedialTheuseof thescrewcuttingdialindicator will be covered in Chapter 12 When using the finefeedyoucanengagetheclaspnutsatanymarkedpositiononthedialsoavoidingweartotheclaspnuts

AtypicalscrewthreaddialindicatorThisoneisengagedanddisengagedbylooseningtheboltandengagingthedrivegearwiththeleadscrew

LATHESADDLEANDAPRON

The saddle is thepart that slides on top of the lathebedandusually has the cross slide and top slide mounted on it Theapron ismounted to the frontof the saddleYoushouldmakesure there isnoplay in the saddle either sidewaysorupanddownandthatittravelsfreelyfromoneendofthelathebedtotheotherwithnotightspotsAtthefrontnearesttheoperatorthereisusuallyapairofclaspnuts(thesearesplitnuts)Thesecan be engaged or disengaged from the leadscrew forscrewcuttingormovingthesaddlealongwiththeleadscrewOncheaper lathes there is usually a solid nut that cannot bedisengaged

ThelathesaddleslidesalongthelathebedTheapronisboltedtothefrontofthesaddle

There is often a rack at the front of the lathe bed thatmatches upwith a handle and gears on the lathe apron Thiscan be used to move the carriage along the bed withoutwearingouttheleadscrewSomelatheshavethecarriagefeedwheel on the right but others have it on the left where hotswarfcanfallontoyourhandsThecheaperlatheshavenorackandrelyontheleadscrewtowindthecarriagebackandforth

ATee-slottedcrossslidemakesthesmalllathemoreversatile

CROSSSLIDE

On top of the carriage is the cross slidewhich canbewoundbackandforthacrossthelathebedWhenusingthecrossslideforfacingacrosstheworkthecarriageshouldbelockedtostopitmovingalongthebedLathesforamateurusearemorelikelytohaveaTee-slottedcrossslidewhilelargercommerciallathesare unlikely to have this facility The Tee-slotted cross slide isveryusefulespeciallyifyoudonrsquothaveamillingmachineYoucanboltworktothecrossslideformachiningusingacutterinthechuckorforboringworkpiecesthataretoolargetoswinginthechuckZero settingdials aredesirable for both the cross slide and

thetopslideTheyallowyoutosetthedialtozerowhichmakesiteasiertomeasuretheamountyouaretakingoffwithonecutInusewindthetooluptotheworkandtouchonsetthedialtozeroandwind the toolbackoff from theworkYounowknowwherezeroisonthetoolandcantaketherequireddepthofcut

withouthavingtoworkitout

Zerosettingdialsmaketurningandscrewcuttingtodepthveryeasy

Apairofzerosettingdialsreadytofit

LathescanbepurchasedwithimperialormetricfeedscrewsMostmodeldesignsareimperialbutmetricismakingheadwayandthismaywellbethewaytogoBewarelatheswithimperialfeedscrewsandmetricdialsTypically thesewillhavea funnynumber of handwheel divisions rather than a whole numberMostofthelathesyoumightcomeacrossareunlikelytohavea

power cross feed for facing This does notmatter as you caneasilywindthecrossslideacrossbyhandTheonlytimeIhavefound a power cross feed to be of use is when I had to faceacross a faceplate to true it up I have trued up similar sizefaceplatesbyhanditjusttookalittlelonger

Thetopslideismountedonthecrossslide

TOPSLIDE

ThetopslideismountedontopofthecrossslideThetopslideisnormallysetat90degreestothecrossslidealthoughitcanusually be swivelled around to various angles for turning ataperanangleorforscrewcuttingSomeofthecheaperlathesdonrsquothaveatopslideasstandardbutitisaveryusefulfeatureif you can get one The top slide should be able to rotateespecially for screwcutting but the top slide handlemay foulthecrossslideincertainpositionssocheckifthisisaproblemTheturningtoolisusuallymountedonthetopofthetopslideItcan either be clamped on directly usually with packing stripsunderneathorthetoolcanbemountedinatoolholdersuchasathree-orfour-waytoolpostoraquickchangetoolpostWewilllook at tool holding methods in Chapter 4 when discussingsettingupturningtools

TAILSTOCK

The component at the right-hand end of the lathe is thetailstock This usually has a handwheel to feed a drill into theworkbut leverfeedandcapstan-style feedingmechanismsarealso available You can lock the tailstock anywhere along thebed The tailstock has a barrel inside it that can bewound inandouttogivealinearmovementtodrillaholeinworkheldinthechuckThetailstockisusuallyboredtoaMorsetaperoftenof a similar size to the headstock so it can take accessoriessuchasdrillchucksmountedonaMorsetaperItcanalsotakeacentre for turningworkbetweencentres It is important thatboth the headstock and tailstock tapers are free frommarksscratchesandburrs

AlathetailstockwiththebarrelextendedNotethatitisnotusuallyaproblemifthechuckkeyisleftinthetailstockwhilenotinuse

Adjustment is usually provided between the base and themain body of the tailstock to allow for setting the tailstock inlinewith theheadstock Tailstocks canbe self ejectingwherethetool isextractedas it iswoundbackwhilesometailstockshavea throughholeandneeda tapwithabar to remove thetool Handwheel depth graduations for drill drilling to a

particularholedepthareveryusefulbutarenotoftenincludedon the cheaper lathes although industrial lathes usually havegraduatedtailstockhandwheelsThebettermakesoflathehavea lever clamping tailstock arrangement while the cheaperlathesoftenhaveaclampingspanneroranAllenscrewclamp

Allguardsshouldbefittedinplacebeforeoperatingthelathe

MACHINEGUARDS

Thedrivemotorcountershaft(iffitted)andpulleybeltsshouldallbeproperlyguarded It isveryeasy togetcaughtup inanunguardedmachineandtheconsequencescanbequitenastyThis has never happened to me but I have seen someonecaught up in a machine and it was not very nice I dorecommend that you make sure your machine guards arecorrectlyfitted

OTHERDESIRABLEFEATURES

Digitalreadoutsareusefulonalatheastheycanshowyouhowmuch to move the handwheels and how much material hasbeentakenoffTheyarequiteexpensivebutyoucan fit themyourself if youare carefulUnfortunatelymost of the cheaperversionsdislikesolubleoilorothercoolantifyougetitintothereadouthead

Adigitalreadoutsuitableformountingonalathe

Youwillneedtwoslidesoneforeachaxis

A soluble pump for cutting fluid is useful and often comesfittedasstandardonthelargerlathesHoweveratinofcuttingoilandabrushwillbegoodenoughformostworkandthatmaysuityoufine

Solubleoilpumpsandreservoirsarereadilyobtainable

Formostjobsyoucangetawaywithsomecuttingoilabowlandabrush

TheMyfordlsquoNortonrsquostylequickchangescrewcuttinggearbox

A Norton quickchange screwcutting gearbox saves time asyou donrsquot have to set up changewheel trains A gearboxhowever considerably increases the price of the averagesecondhand lathe A Myford Norton gearbox has twenty-fourpitchesandiscontrolledbytwoleversReversingtwogears inthe Myford changewheel train gives the gearbox twenty-fourfine feeds insteadof the twenty-fourscrewcuttingpitchesThegearboxhasa setofgearsarrangedasaconeBysliding thelever along and dropping themaster gear onto the cone youcanchangethegearboxratioandsothepitch

TheconegearsinsideatypicalNortonscrewcuttinggearbox(notanoriginalMyfordone)

SeveraldesignshavebeenpublishedtomakeyourownNortontypescrewcuttinggearboxThisoneisavailablefromHemingwayKits

SPINDLESPEEDS

Thespeed rangeneededona lathedependson thework it is

requiredtodoAgoodrangeofspindlespeedsisdesirablewithnoobviousgapsWithelectroniccontrolthisshouldnotbetoomuchofaproblemIdeally a back-geared lathe would be best but this means

either a good secondhand machine such as a Myford or aBoxford or alternatively one of the larger Asian-made latheswithanall-gearedheadstock

Thisbackgeararrangementisswitchedinandoutbyturningthetoggleonthepulleyandliftingaleveratthefrontofthelathe

Backgearnormallyconsistsoffourgearstwolargeonesandtwosmalloneswhichcanbeswitched inorout toreducethespeedofthelathebyaratioofusuallyabout51dependingonthe maker to enable you to turn large diameter workpiecesThis reduction is also essential on a screwcutting lathe asotherwisethemandrelwillbegoingtoofastwhilescrewcuttingandyouwonrsquotbeable tostop in the rightplaceat theendofthethreadIf buying a back-geared lathe check that both gearwheels

havealltheirteethItisamajorjobtostripdownalatheandfitnewgearwheelsassumingtheyareevenavailableassparesCheckthelatheinallgearrangeswiththelatherunningIfa

back-geared lathe or an all-geared head is noisy it could

indicatewearitwillalsobeanuisanceinyourworkshopasnoonewants to hear a noisymachine runningNoise could be amajorproblemespeciallyifyouhaveneighboursnearbyGearedheadsusuallyhaveawiderangeofspeedsthelarger

industrial lathescangoup tospeedsof2000rpmandsmallerversionsareoftenhigher

Anall-gearedheadonamodernindustrialsizelathe

On the more usual amateursrsquo lathe there is often acountershaft usually tensioned by a lever which tightens upthebeltreadyforuseThemiddlespeedofthecountershaft isusually chosen to be about one quarter of the motor speedMost small lathes have three speeds and the back geararrangement adds another three speeds giving six in all TheMyfordSuper7rangeoflatheshavefourspeedsandbackgearmaking eight speeds but there is also a double pulley on themotor countershaft section making sixteen speeds in allalthoughtheverylowestback-gearedspeedswillrarelyifeverbeusedSomeoftheolderColchesterChipmasterlatheshavewhatis

knownasaKoppVariatordriveThis isavariable speeddrivecontrolledbyadialandthesystemworkswellbuttheVariator

isveryhardtoreplaceifthedrivefails

ThissmallCowellslatheiscapableofdecentworkandatthetimeofwritingisprobablytheonlylathestillbeingmadeinBritain

MOUNTINGTHELATHE

There are three main options for mounting a lathe benchmounting portable or on a stand Ideally a makerrsquos standshouldbeusedformountingamediumto large latheandthestandisoftenanintegralpartof larger lathesAsmaller lathesuch as a Unimat or a Cowell can bemounted on a woodenchopping board or a similar small board These lathes can beputawayinacupboardafteruseThe alternative is a workbench but these are often made

from wood which can expand or contract depending on themoistureintheairWoodisnotagoodmaterialfromwhichtomakea stand for a larger latheas itwill attractmoisture andmayexpandshrinkordistortAmetalstandisabetteroptionWewilllookatinstallingthelatheinChapter2

AnArcEuroTradeC3screwcuttinglathemadebySiegThisisaverypopularentrylevellatheandmanyaccessoriesareavailable

Amedium-sizedscrewcuttinglathesuitableforgardenshedworkshops

SHOULDIBUYNEWORSECONDHAND

Beginnerssettingupaworkshopoftenaskifitisbettertobuyanew lathe or secondhand The preceding pages should have

given some guidance but there are more points to be takenintoconsideration

Alargerindustriallathewithafoot-operatedemergencycut-offswitchandbrake

BuyingNew

Thelistoflathesuppliersincludedatthebackofthisbookwereall in business at the time of writing Most will be willing todemonstratetheirrangeofmachinesattheirpremisesorwhileattendingmodelengineeringexhibitionsPaycloseattentiontomechanical noise the general paint finish and the workingslideway surfaceswhich should begroundDoes themachinehave sharpor roughedges (Handwheelsareespeciallypronetosharpedges)The main thing to consider though is the attitude of the

supplier Were they willing to talk to you and answer yourquestionseitheratanexhibitionoroverthephoneHowlongdo they take toanswer thephonewhenyou ring their servicedepartment Do they know the answer to a simple questionstraightawayordotheyhavetogetbacktoyouIsthemanual

written in English or Chinglish (translated awkwardly fromMandarinorCantonese)There are several suppliers of new lathes inmost countries

aroundtheworldbutthemajorityoflathesaremadeintheFarEastOftensupplierArsquosmachinescomefromthesamefactoryassupplierBrsquostheyarejustpaintedadifferentcolourandhavedifferentnamesandlabelsfittedAftersales service can vary greatly Usually companies that

havebeeninbusinesslongerwillofferbetteraftersalesservicebutotherpeoplersquosexperiencescanbefoundonInternetforumsoratlocalmodelengineeringclubsUsually theAsian lathesare reasonablywellmadebut they

often suffer from having plastic gears instead of metal onesOneortwocompaniessupplymetalgearsasstandardso it isworthaskingiftheirmachineshavemetalorplasticdrivegearsSome companies also offer after-market replacement metalgears

BuyingSecondhand

There aremany good quality secondhandmachines availablebut there is also a lot of worn-out rubbish If possible take aknowledgeable friend with you when purchasing a lathe Becareful when buying at online auctions such as eBay MostsellersaregenuinebutsomearenotNeverpartwiththecashuntil youhavechecked the latheover IhaveboughtoneBaywithoutproblemsbut Iamcarefulwhat IbuyandwhofromAsmall latheforacoupleofhundredpoundsisunlikelytobreakthe bank if it is a bit of a dog but a lathe that costs severalhundredpounds is adifferentmatter ThegreenMyfordML7RpicturedthroughoutthisbookwaspurchasedfromeBayItwasbrand new the motor had never been fitted and it was abargainwhencomparedwiththeretailpriceIdidpaycashoncollectionbutIwouldhavewalkedawayif ithadnotmatchedthedescriptioninanywayWhether purchasing new or secondhand check what

accessoriescomeaspartofthepackageandwhatwillneedto

bepurchasedseparatelyEssentialtoolingcanoftendoublethecost of a newmachine if it is not included in the price whilededicatedtoolingmaynotevenbeavailable forasecondhandbargainlathe

Youshouldnowhaveanideaofthesizeoflatheyouneedthefunctionofthedifferentpartsofthelatheandwhetheryouarebuying new or secondhand In Chapter 2 we will look atinstallingthelatheandsafetyintheworkshop

2InstallingtheLatheandUsingItSafely

If you are buying a new lathe completewith delivery to yourworkshopyoucangostraighttothesectiononsettingthelatheupIfyouarecollectingthelatheyourselfhoweveryoushouldpayattentiontoafewwordsonmovingit

Ifyouhaveroomtomanoeuvreanenginehoistcanbeusedtomovemachineryaroundsafely

MOVINGTHELATHE

MOVINGTHELATHE

When going to collect your lathemake sure someonewill betheretohelpyouloaditortakesomeonewithyouUnlessitisaminiaturelatheitwillbetooheavyforonepersontoliftHelpisalsoneededwhenyougetthelathehomeLiftingthelatheoutofacarcanbeharder than lifting it in It isadvisable tohavethreepeoplewhenunloading twoat theheavyheadstockendandoneliftingthelightertailstockendYoucanrentorbuyanenginehoist fora reasonablepriceand this canmakemovingthemachineeasierIf the machine is a substantial industrial type it would be

besttohireatransportcompanythatspecializes inmachineryremovals Professional machinery removers will usually haveproperlyequippedtransporttomoveheavymachinesThiswillprobablyworkoutcheaperthanattemptingtodoityourselfbutmake sure they have insurance in place in case they damagethelatheoryourpropertyYoushouldalsoensuretheyknowithas to beput in place as required in theworkshop youdonrsquotwanthalfatonofmachinerydumpedonyourdrivewithnowayofmovingitintopositionLathesareusuallytopheavywhenbeingmovedandcantip

overifyouarenotcarefulTheMyfordML7seriesforexampleoftenhasthemotorandcountershaftboltedtothebackofthelathe bed and this type of lathewill tend to tip backwards Asimple solution is to bolt two lengths of wood about 4 times 2in(100times50mm)tothelathefeetOneboltineachendwilldoifyou canrsquot drill holes in the correct position This will stop thelathe tipping backwards and also make it easier to lift IfpossibleyoushouldremovethetailstockThisisoftenaheavylumpofmetalbutitisusuallyveryeasytoslideitofftheendofthelathebedAnyotherlargeobjectsthatcanberemovedandreplacedlaterwillmakethelathelighterandeasiertomove

Twoplanksofwoodboltedtothelathefeetwilloftenturnanunmanageablemassofmetalintoaneasilyhandledmachine

Azerovoltsswitchisessentialequipmentonanymachinetool

Wearoldclotheswhenmovingyourlatheandhaveplentyofold rags to wipe off swarf and oil Lay down old blankets ordecoratorsrsquosheetsinsidethecarandasheetofthickcardboardMDForplywoodtohelpprotectthebootareawhenslidingthelatheintothecar

AsmallishlathecanoftenbefittedintoastandardhatchbackorestatecarYoumayfindhowever thatyouhavetodotwotrips one for the lathe and accessories and another for thecabinetthelathestandsonTosaveawastedjourneyIusuallytrytofitthelathecabinetinfirstIfIthenfindthatthecabinetdoesnrsquotfitIcanstillbringthelatheandtoolinghomeknowingthat Ihave tohireavan tocollect thecabinetbutalso that IhavenothadawastedjourneyIfyouhavetosplittheelectricsforexampletotakethelathe

offthecabinetdrawadiagramoftheelectricalconnectionssoyoucanrewirethelathewhenyougetithomeAdigitalcameraisalsoagoodmethodofrecordingthewiringconnectionsbutIwouldnotrelyonthecameraaloneIf the lathedoesnothaveazerovoltsswitch itwouldbea

good idea to fit one after you get the lathe home They areavailable quite cheaply andare easily fitted If in doubt aboutyourabilitytodoelectricalwiringconsultaqualifiedelectrician

Adjustablefeetareveryusefulforlevellingupthelathe

SETTINGUPTHELATHE

Somelathesusuallythelargerindustrialoneshaveanintegral

bedandcabinetThelathecanbesettotruewithjustshimmingunderthefeetorbyadjustingthefeetOther lathes may need to be mounted level and true to

ensureaccuracywhenturningSetthebenchstandas levelasyou can in both directions using a spirit level as a guide Anycheapspirit levelwilldoas longas it isaccurateYoucantesttheaccuracyofaspiritlevelbyturningitround180degreesifitisaccurateitshouldreadthesamebothwaysOnce the stand is reasonably level youcan level the lathe

ThisinvolvesjackingorshimmingupthelatheuntilitistrueinbothdirectionsIfusingawoodenbenchputmetalplatesunderthe feet tospread the loadShimoradjust the latheuntil it isreasonablylevel

Putthespiritlevelonthecabinetrsquoslongitudinalaxisandusetheadjustablefeettolevelthelathe

Insertalengthofbarinthechuckandputadialtestindicatoron top of the tailstock end of the bar Nip the headstock endmounting bolts down first and then tighten down the tailstockendboltsAdjustorshimthetailstockenduntilthereisnosignof movement on the test indicator Next 64repeat theprocedure with the dial test indicator on the front of the barAgainyouare looking fornomovementCheckbothdirectionsagainmakingsurethereisnomovementeitherhorizontallyorverticallywhenyoutightenthelathedownAdjustorshimuntil

there is no movement in either direction when the lathe isclampeddownAslongasthebedisnottwistedthelathebedshouldnowbetrue

1Insertapieceof⅛in(3mm)packingunderthespiritlevelatthetailstockendThiswillresultinarunonthedriptrayandalltheoldoilwillruntotheendofthelathemakingiteasiertocleanup

2Placethespiritlevelonthecabinetcrossaxisandusetheadjustablefeettolevelthelathe

3Putthespiritlevelonthelathecrossaxisattheheadstockendandlevelitasbestyoucan

4Putthespiritlevelonthelongitudinalaxisandlevelalongthelathe

5Testthetopofthebarthereshouldbenomovementwhenthelatheisclampeddown

6Testthefrontofthebaragainensuringthatthereisnomovementwhenthelatheisclampeddown

Alignthetailstockbyusingadialtestindicatorintheheadstock

AligningtheTailstock

NowweneedtosetthetailstockinlinewiththeheadstockDothisbyputting thedial test indicator into theheadstockchuckandtestthetailstockboreAdjustthetailstocktowardsthefrontortothebackofthebeduntilthetestindicatorreadstrueandtighten theclampscrewsA slightdifference inverticalheightwillnotbetheendoftheworlditjustmeansthereisprobablysomeweartothebaseofthetailstockcastingbutthereshouldbenovariationfromfronttobackinthehorizontalalignmentPutalongbarbetweenthecentresandtakealightcutalong

it using a fine power feed Run along the bar a couple moretimes at the same setting to remove any push offWhen youmeasure thebar it shouldmeasure the sameatbothends Ifthe bar is larger at the tailstock end you need to reduce theheightofthebedatthefrontofthetailstockslightlyIfsmalleratthetailstockendyouneedtoreducetheshimatthebackofthe tailstockend Itprobablywonrsquotneedmuchadjustmentasslightadjustmentstotheshimoradjustersatthetailstockendwillsoonbringitintoline

Usingatestbartocheckforparallelturning

LubricatingtheLathe

You should follow the manufacturerrsquos recommendations forlubrication Usually this is thin oil for the headstock oftenhydraulicoilandslidewayoil forthemovingpartsLubricationshouldbedoneregularlyIfthelatheisfittedwithasightfeedoileritshouldshowoilinitAdjustablesightfeedoilersasusedonMyfordandsimilarlathesshouldbeadjustedsothattheoildripswhen the lathe is running but does not dripmuchwhenthe lathe is stopped The slight vibration when the motor isrunningisusuallyenoughtocausetheoiltodripToomuchoilisbetterthannotenoughoilisfarcheaperthannewbearings

Atypicaldrip-feedlubricator

UseanoilgunonalltheoilnipplesYoucangetaroundthetendencyfortheoiltogoeverywhereexceptintothenipplebyputtingapieceofwritingpaperoverthenippleandthenusingthe oil gun as normal The paper will stop the oil squirtingeverywhereThemandrelbackgearalsoneedstobelubricatedWheninusethemainbackgearisrunningontheoutsideofthelathemandrelandneedstobelubricatedoftenoritwillgethotandwearChangewheels should be lubricated with oil not grease If

youusegreaseswarfwillsticktothechangewheelsandcauseunnecessarywearTo stopswarf running through themandrelanddroppingoutontothechangewheelsputawinebottlecorkor similar into the left-hand end of the mandrel This willeffectivelystopanyswarfgettingthroughtothechangewheelsOil the saddle and cross slide and also the nipples on the

tailstock Make sure oil is showing at the edge of the slidingsurfaces A squirt of oil on the cross slide and topslide feedscrew bearing is needed as well Check the manufacturerrsquosinstructions for lubricating the rest of the lathe Follow themotormakerrsquosrecommendationforlubricatingthemotorTrytoavoidusingWD40onthelatheWhileitisanexcellent

lubricantwaterdisplacerittendstodiscolourthelathebed

Useabitofpaperundertheoilguntostoptheoilsquirtingeverywhere

AvoidingtheRustFairy

Rust canplayhavocwith a lathe quickly turning thebedandother parts into a brownmess Various sizes of plastic coverssuitable forcovering lathesareoftensold foruseasbarbecuecoversinDIYstoresAplasticlathecoverwillhelptokeeprustatbaybutmoreneeds tobedoneAbagcontainingsilicagelplacedundertheplasticcoverforexamplewillabsorbexcessmoisturesilicagelcanbeboughtverycheaplyoneBay

SilicageliseasilyobtainablefromeBay

Alternatively you can buy a vapour phase inhibitor forprotecting the lathe The vapour phase inhibitor chemical issuppliedonafeltpadinsideaplasticpotThechemicalformsaprotectivelayeroneverysurfaceBecauseitisavapouritwillfind its way into every cranny and is also used for protectingtools and accessories in tool cabinets and drawers It usuallylasts for twelvemonths ifenclosedby theplasticcoverSomemachinetooldealersareabletosellsuppliesofthisproductinsmall ready to use containers rather than in industrialquantitiesAlwayscleanthelathedownafteruseswarfwillsoonrustif

leftonalatheasitwillprobablybecleanfromturningandwillnotbeprotectedbyoilTheuseofanovencookingtrayunderthe lathe bedmakes it easy to remove swarf at the end of aturning session The tray also helps to retrieve a parted offcomponentora lost screw froma tipped turning toolAnotheralternativeistocoverthelathechiptraywithnewspaperwhenyouhave finished turning remove thenewspaper screw it upandthrowitawayWhenfittingachuckorfaceplatetothelathemakesureyou

cleanthemandrelthreadtheregisterandthefaceYoushouldalso clean the mating threads the bore and the face on thechuckorfaceplateYoucancleanthethreadandboreeasilybyusing two toothbrushes bolted back to back with spacers inbetween Make sure the Morse tapers in the headstock andtailstock are cleanbefore fitting aMorse taper accessory TheMorse taper to be fitted should be free from scratches burrsandbruisesIt is good idea tomake a chuck board for usewhen fitting

chucks to a lathe or removing them This is a piece of wood(plywood will do) that sits on the lathe bed while you arescrewingthechuckonandoffThechuckboardwillprotectthelathe ifyoudrop thechuck It canalsobeused toprotect thelathebedwhenyouarehacksawingorfilinginthelatheIf you keep your lathe clean and lubricate it regularly it

shouldlastalifetime

AlargetraywillcatchmuchoftheswarfandtheholeslettheoildrainawayUsenewspapertosoakuptheexcessoil

SAFETYINTHEWORKSHOP

RememberyouareresponsibleforyourownsafetySafetyisamajorconcernintheworkshopTherearecertain

thingsyoushoulddoandobviouslythingsyoushouldnotByitsverynatureaworkshopcanbeadangerousplaceallwecandoismakeitassafeaspossiblewhilestillallowingustoworkinit

WorkingAlone

Mostofyoureadingthisbookwillprobablybeworkingaloneinasmallworkshopgarageorgardenshed IfyougethurtyoumaypossiblybeonyourownAsapriorityIsuggestyoutakeamobilephoneintotheworkshopandkeepitinyourpocketTheability to contact your family a friend or the emergencyservicesquicklycouldsaveyour lifeKeepthephoneswitchedoff while in the workshop however as it is an unnecessarydistraction

FirstAid

FirstAid

AFirstAidboxwithcontentsisanecessityandshouldincludeaneye-bathandeyewashYoushouldparticularlylearnhowtostopbloodflowingThereareplentyofwebsitesthatwilltellyouhowtodothisCheckthemoutnowbeforeyougobackintotheworkshop

ElectricalSafety

Checkforearthcontinuitywhilethemachineisunpluggedwithavoltohmmeterfromtheearthpinonthethreepinplugtothemetalpartofthelathe(somepaintmayhavetoberemovedforareadingtotakeplace)Youshouldgetareadingofzeroohmsorabeep if themeterhasacontinuity rangeYoushouldalsobe sure that the electrical sockets on the wall are correctlyearthedIfindoubtconsultacompetentelectricianLightingandelectricheatingshouldbeonaseparatecircuit

tothemachinessoyouwillstillhavelightifthemachinestripoutPlugasmalllightintothemachinecircuitsoyouhavesomelight if the lighting circuit trips out When I go on holiday Ialwaysturnoffthefusetripsforthelightinginordertomakeitmore difficult for intruders to move about quickly Leave thehouse alarm and smoke detectors on (The house alarmmayactivateeighthoursafter theelectricity is turnedoffwhenthebatteryexpires)

Adigitalmultimeterisveryusefulinthehomeworkshop

BeAware

Bementally alert while using the lathe Avoid operations thatmightputyourhandsatriskofenteringthemovingpartsofthelathe Do not operate any lathe while under the influence ofdrugs alcohol or prescription medication that may causedrowsinessorotherwiseaffectyourability to control the lathesafelyDonotattempttoworkonalatheandtalkatthesametimeIfyouhavetotalktosomeoneswitchoffthelathebeforedoingso

KeepItClean

TheareaaroundalatheshouldbekeptfreeofobstructionsThefloorshouldbecleananddrywithanyoilorotherspillscleanedup immediately The lathe should be kept clean and tidyMachinedangerareasshouldbemarkedontheworkshopfloorand observed Workbenches placed near a lathe should be

strongandequippedwithanon-slipsafetysurfacetostoptoolsor other items rolling onto the floor a rubber car mat willsufficeA rubberdoormat on the floorwill allow swarf todropthrough in order to save you getting swarf embedded in thesolesofyourshoes

Asuitablefloormatwillallowswarftodropthroughandhelpkeepyourfeetwarminwinter

LearntoUsetheLathe

Donotuseany lathebeforeyouare familiarwith thecontrolsandareawareofthedifferentwaysofstoppingitThismaybea clutch an onoff switch a No Volts release switch or anemergency stop button I strongly advise fitting a No VoltsreleaseswitchifyourlathedoesnothaveoneAswellasbeingusefulforstoppingthelatheinanemergencyitwillpreventthelathefromstartingupbyitselfafterapowercutIfyouarenotcomfortableworkingwith electrical equipment get a qualifiedelectriciantofittheswitchforyou

StaywiththeLathe

Nevereverwalkawayevenforamomentwhilethelatheyouare using is switched on Switch it off if you are leaving itunattended and only leave the lathe after it has come to a

completestopNeverleavealatheinanunsafeconditionMakesure that you have not left the chuck key in the chuck Thechancesarethatifyouarehalfwaythroughsettingupthelathewhen you return you will forget what you have or have notdoneIfindoubtleaveabignoticeremindingyourselftocheckthatthelatheissafebeforecontinuing

Donotleavethechuckkeyinthechuck

SwitchOffwhenAdjustingtheLathe

Shut off the power supply to the motor before starting anyoperationsrequiringaccesstothelathesuchaschangingtoolsmeasuring work mounting or removing accessories changingspeed and setting up change gears The lathemust be safelystopped Just zeroing a variable-speed drive is not safelystoppingitusethezerovoltsswitchtoswitchthepoweroffaswell

CheckbeforeStartingtheLathe

AlwaysrotateyourworkpiecebyhandtomakesureitclearsthetoolrestsaddleandbedDoublechecktomakesureyourworkis securely clamped in the chuck or between centres beforestartingthelatheBecertainthattheworkpieceturnsfreelyand

isfirmlymountedThespeedofthelathemustbecheckedbeforeturningiton

When turning irregular shapes start the lathe on a low speedandincreasethespeedbyapulleystepeachtimeIfthelatheisbouncingabout lowerthespeedandorbalancethework Ifthe work vibrates stop the lathe and check the reason ThechancesarethatyouarerunningthelathetoofastMeasuringequipment toolingandworkpiecesshouldnotbe

leftona latheastheycanvibrateoff intomovingcomponentsand be thrown around the room Check for loose items on alathebeforeuse

UsetheLatheGuards

NewlatheswillbefittedwithguardsoverthemotorshaftdrivebeltandspindlepulleysTheseguardsshouldalwaysbeinplacebefore using the lathe Any other moving parts should beguardedtopreventanythingfallingontothemovingpartsAlthoughguardsareoften removedbymachinistsprovided

they are constructed from clearmaterials and open and closeeasily theyaddsafetywithout interferingwith theworkbeingdone Guards will at the same time deflect swarf and anycoolantthatisbeingusedGuardsfittedtothelatheshouldnotbe removed while it is in use They should be made fromsuitablematerialandnothavesharpedgesTheyshouldnotberemovedforadjustmentandlubricationofthelatheunlessthisis unavoidable Lathemanufacturers donrsquot usually supply chipguards soaddingoneshouldbeconsideredChipguardswithmagnetic bases are available although they can attract steelswarftothemagnetPutthebaseintoaplasticbagtoaidswarfremoval

UseEyeProtection

Lathes can throw sharp metal chips considerable distancesespecially at high cutting speeds Apart from deep cuts thechipsmay leave the tool red hot cause skin burns and even

burnholes in clothing Youmust use safety goggles or propersafetyspectacleswhileintheworkshopAlwayswearindustrialqualitysafetyglassesfittedwithsideshieldsSpectacleswithoutsafety lenses are not adequate eye protection When theglasses get dirty do not wipe them off as they will becomescratchedWashthemoffunderthetapinstead

TakeCarewhenRemovingSwarf

Do not attempt to remove chips or turnings with your handsAlwaysswitchoff the lathefirstandeitherpull theswarfawaywithalargemetalhookorliftitoffusingapairofglovesIftheswarf is tangled around the lathe untangle it with a pair ofpliersandnotaglovedhandasitwillcutstraightthroughtheglovesandintoyourhandUseadustpanandbrushtoremovesmall chips and swarf from the swarf tray ndash never use yourhandsWhenswarfbecomesstringyandbuildsuponthetoolortoolpostturnoffthelathebeforeremovingit

AvoidLooseClothing

IfyouarenotwearingoverallswearshortsleevedshirtsorrolllongshirtsleevesabovetheelbowsLoosesleevescancatchonrotatingworkandquicklypullyourhandorarmintothe latheObviously though keep your arms protected if hot swarf isflyingaroundSwarf can get inside protective clothing especially collars

(useaclothespegtokeepyourcollartight)pocketsandshoesTostopthesleevesofanoverallcatchingsewelastic intothecuffsorwrapacoupleofthickelasticbandsaroundthecuffstostopthesleevesgettingcaughtupUnder no circumstances wear a necktie when operating a

latheProtectiveglovesshouldneverbewornwhileoperatingalathe Protective gloves may be worn when swarf is beingremovedbuttheymustberemovedbeforeswitchingthelathebackon

UseSturdyFootwear

WearsteeltoecapsafetybootstheyarenotexpensiveandwillhelptoprotectyourfeetfrominjuryifyoudropaheavyobjectonthemThelsquotrainerrsquoversionisparticularlycomfortableDonotallow stringy swarf to fall on the floor as youwill get cuts onyouranklesandmayeventripoverit

AvoidJewellery

Do not wear wristwatches rings or jewellery when in theworkshop as it could catch on a rotating part of the lathe orworkpieceThisalsoapplieswhenmovingalatheintooroutoftheworkshopsincetheycouldcatchona falling lathe IfyourotherhalfcomplainsthatyouhavetakenoffyourweddingringexplainthatyouwouldnrsquotbeabletowearitagainifyourfingerismissingduetoanaccidentLonghairshouldbetiedbackasyoucouldbepulledintothelatheifitgetscaughtintherotatingwork

LiftingintheWorkshop

Back injuries can be caused by incorrect lifting practices It isimportant to bend your legs when lifting rather than bendingyour back A hoist or engine lift should be used to lift heavyitems A stool in theworkshopwill take the pressure off yourlegs and will provide a welcome break after you have beenstoodatthelatheforawhile

Self-ignitingMaterials

If you machine titanium or magnesium which can ignite andburn vigorously keep the accumulation of turnings to aminimum If thematerialdoescatch firedonrsquotusewaterorawater-based coolant as an extinguisher since it will makematters much worse Before starting to machine titanium ormagnesiumfillalargebucketwithdrysandcoveritandkeep

it by the lathe The sand will smother the flames veryeffectivelyYoucouldalsobuyoneofthespecialfireretardantsusedinindustryBeware also of grinding aluminium on the bench grinder

Aluminium and steel filings are the ingredients of Thermite apowerful explosive that can also burn If you grind aluminiumandthenchangeovertogrindingsteeltheredhotsparksareliable to set the steelaluminium mix on fire This is a verydangerous combination ofmaterials and should be avoided atallcosts

SafetywithBarStock

Bar stock should be contained within the headstock and notallowed to protrude from the rear of themandrel I once sawsomeone switchona lathewhenabrassbarwas stickingoutfrom the back of the headstock by about two feet With thelathe running at 2000rpm the bar whichwas aboutfrac34in (19mm) in diameter was bent at right angles and caused theheavy lathe which weighed 1280kg to jump about Luckilysomeone managed to switch the lathe off before any majordamageoccurredItwasnottheoperatorhehadrunwellawayandwasnowheretobeseen

SomeFinalWordsonSafety

Wherever possible the machine height should be adjusted tosuittheuserWearestillusingfifty-year-oldmachinesbutfiftyyearsagothenationwasshorterTheworkplaceshouldbeprovidedwithuniformlightingthat

gives an adequate level of illumination Individual machinelightsarebestThe lathemust be set to operate at the speeds and feeds

recommended for thespecificmetalbeingturned If themetalrotatestooslowlyortooquicklyorthefeed istooslowortoofastaccidentsarelikelytooccurThe area directly in front of and behind the workpiece is

known as the lsquofiring zonersquo or the lsquored zonersquo This is where apiece of work is likely to go as it leaves the lathe Make it ahabit to keep clear of this zone when you turn the lathe onLearnwhere theNoVolts switch is as youmightneed to turnthelatheoffquicklyByfollowingalltheaboveadviceyoushouldnowbeableto

worksafelyfullyawareofanysafetyproblemsthatmightariseAtthispointyounowknowhowtoinstallthelathelookafter

itclean itandmaintain it InChapter3wewill lookatcuttingtoolsandexaminehowtoselectcuttingspeedsandfeeds

Thisbarisstickingouttoofarfromthebackofthelathe

3CuttingToolPrinciplesFeedsandSpeeds

The first part of this chapter will look at the materials fromwhichcuttingtoolsaremadeaswellastheirbasicshapeandgeometryWewill thenconsider selectingsuitablespeedsandfeeds

MAINTYPESOFTURNINGTOOLS

There are three main types of turning tool used in modernworkshops HSS (high speed steel) tools carbide brazed-ontoolsandinsertedtiptoolsAllhavetheirusesintheworkshopandformost jobsthere isnopreferenceforonetypeovertheothersTherearealsocarbonsteeltoolbitsalthoughinpracticetheyarejustaboutobsoleteCarbonsteeltoolscanbemadeinthe homeworkshop but apart frombeing used tomake formtools(seeChapter11)thereaderisunlikelytousethismaterialfortools

Ageneral-purposeHSSturningtoolsuitableformildsteel

HSSTOOLS

HSStoolscanbepurchasedsinglyorinsetsalreadygroundtothecorrectshapeIt ischeaperhowevertopurchasethemassquare tool blanks in various sizes ready for you to grind toshapeThecompleteready-groundsetswillprobablycomewithseveralshapesincludedthatyouwillneveruseIfyoucanbuyafewready-groundtoolscheaplytheywillbeofuseasguidestoseehowtosharpenyourownHSStoolblanksHSS form tools from industry are often available second-

handTheseareespeciallygroundtomachineacomplex formall in one go You can often find some that are ground to asuitable shape to form the end of a threaded componentincludingtheundercut

HSSformturningtools

Brazed-onCarbideTools

Brazed-on carbide-tipped tools are quite useful especially forfacing and boring cast iron but they really need a diamond-facedgrindingwheeltokeepthemsharpCarbidetipsandtoolscomeinvarioussizesandhardnesstosuitindividualmaterialscarbidetoolsforsteelwilloftenbepaintedbluethoseforcastiron are painted red and those for stainless steel are paintedyellowThecolourindicatesthesuitabilityofthetoolforcertainmaterials

Brazed-oncarbide-tippedtoolscomeinvariousgradesshapesandsizes

InsertedTipTools

InsertedcarbidetiptoolsareveryusefulbuttheyarenotcheapThe tipsarenotusually sharpenedafterwearingout you justthrow the tip away and fit a new one Most modern carbide

inserts however do have more than one cutting facesometimestheyhavetwoandoccasionallyfourormorecuttingedgesareavailableYoucanevengetformturningtoolswheretheinsertisroundandcanberotatedafull360degrees

Theleft-handtoolisblueindicatingitisformildsteelwhiletheright-handtoolisredindicatingitisforturningcastiron

Some diamond-shaped tips can be used in different toolholders two edges are used in one tool holder and the othertwoedgesareusedinanothertoolholdersoyougettwicethelifepertipInserted tip tools are available for internal and external

screwcuttingwherethetipsareheldat thecorrecthelixangleofthethreadinthetoolholderThedrawbackisthecostofthetipsandeachsizeofthreadusuallyneedsitsownsizeoftip

Aninsertedtipcarbideturningtool

Carbidegroovingtools

InsertedtipgroovingtoolsareidealformachininggroovesforOrings and circlips Theyare available inmany standardwidthsandcanoftenbeusedasparting-offtoolsforsmallerdiametersOneof themostusefulgrooving tools forsmallersizegroovesandpartingoffistheMiniThinsystemassoldbyMSCIndustrialSupplyCo

TheMiniThintoolholderisidealforgroovingandalsoforpartingoffsmalldiametersTheshankissostrongcomparedwiththecutbeingtakenthatusinganoverhangasshownisquite

safe

Coatingstoreducetoolwear

Tipsarealsoavailablewith various coatings that improve toollifeThemostcommoncoatingistitaniumnitride(TiN)whichisgold in colour Other coatings that offer slightly better wearresistancearetitaniumcarbonnitride(TiCN)whichisbluegreyincolourandtitaniumaluminiumnitride(TiAlN)whichisvioletbronzeReady-groundHSScuttingtoolssuchasdrillstapsandreamers are also available with these coatings but once yousharpenthecutterthecoatingisgoneTipped toolsneedadeeper cut ahigher feedandahigher

speed than HSS tools Thismeans that the lathe needs to bestrongrigidandhaveamplepowertodrivethe lathemandrelwhen taking a heavy cut this rules out using tipped tools onlathessmallerthanabout2in(50mm)centreheightSmaller tools are made to fit the Unimat and similar small

lathesbutthesemachinesjustdonrsquothavethepowerneededtodrivethemAtbesttakingacutwillstopthelatheatworstthetoolwillchip

Insertedtiptypes

Inserted tip tools come in many shapes and sizes Some tipshapes and sizes are made to an international standard andothers are to the makerrsquos own standards Wherever possibleuse ISOstandardtoolsas thetipswillbe interchangeablewiththosefromothermanufacturersandwillprobablybecheaperaswell The ANSI system commonly used in the USA is notcompatiblewiththeISOsystemusedintherestoftheworldIfyour lathe ispowerfulenoughyoucantakeadvantageof

insertedtippartingoffbladesThesearemounted inaspecialtoolblockandthebladecanbeslidinoroutdependingonthediameteryouarepartingoffThebladecarriesan inserted tipspecially designed for parting off There are three types of tipavailablesquare-endedtipstipsthatareangledtotheleftand

tips that are angled to the right Square tips are used forgeneral parting off tips angled to the left are usedwhen youdonrsquotwanttoleaveapiponthebackendoftheworkandtipsangledtotherightareusedwhenyouwantacleanfaceonthefrontoftheworkThe parting off blade is oftenmounted upside down at the

backofthe lathecrossslideTheactionofpartingofftendstolift the whole cross slide slightly and forces the cross slidetightly into thematching dovetail whichmakes itmuchmorerigidIfthepartingofftooldigsinwhileinthebacktoolpostthetool tends to lift and push away from the work whereas in afronttoolpostthetooltendstodiginandpullintothework

Simplifieddiagramofpartingofftoolangles(A)straightpartingtool(B)angledtotheleft(C)angledtotheright

POWERREQUIREMENTS

Whenturningmildsteelorstainlesssteelwithanycarbidetoolthe machine horse power required is considerably more thanthat required forordinaryHSStoolsThe twomain reasons forthisarethatcarbidetoolsoftenhaveanegativerakeangleonthecuttingedgeasthistypeofedgelastsmuchlongerthanapositiveangle especially for intermittent cuts andbecause in

industrial use carbide tips are called on to remove largerquantitiesofmetalathigherspeedsandfeedsFor guidance on using tipped tools in the small workshop

wheretimeisnotasimportantasinanindustrialenvironmentIwould recommendusing twice the speedused fornormalHSStools and a fine feed of about 0002in (005mm) per rev as astarting point This can be adjusted up or downdepending ontheresultsThemaindifferencebetweenHSStoolsandcarbidetippedtools(eitherbrazed-onorinsertedtip)isthehorsepowerrequirementofthemachineinuse

Thispartingofftoolismountedatthebackofthelatheinaspecialbacktoolholder

SELECTINGTHECORRECTSPEEDSFORDIFFERENTMATERIALS

Overmanyyears through trialanderror cuttingspeedshavebeendeterminedthatgiveanoptimumtoollifebalancedwithadecent surface finish These speeds are normally quoted inlsquosurfacespeedinfeetperminutersquoSpeeds and feeds used on industrial machines where the

primary tools will have inserted tips will be a lot higher than

thoseusedinthesmallworkshopwhereHSStoolsarethenormThe accompanying table gives an idea of the speeds that

shouldbeused forvariouscommon typesofmaterial likely tobefoundintheworkshopThespeedslistedshouldbesuitableforbothturninganddrillinginthelatheForreaminguseabout25percentoftherecommendedspeedsThe table is a guide only and it is likely that the machine

speedsavailablewillnotbeexactlythoserequiredandyoumayhavetoresorttolsquonearenoughisgoodenoughrsquoSetthelathetothe nearest speed lower than indicated in the table for thediameterandmaterialbeingcutThiswillbefineforHSStoolsDouble the recommended HSS speed for carbide tools For

parting off use about 30 per cent of the recommended HSSspeed For form tools use about 50 per cent of therecommended speed for the initial cuts and then engage thecorresponding back gear (just switch to back gear leaving thebelts on the same pulley) and gently tap the handle until itreachesthefinishedsizeandallowittofinishthecutbyitselfYou may have to adjust the speed down if you get a lot ofchatter

Forturningcastironuseacarbide-tippedtoolrunningattheHSSspeedtoremovetheskinYoucanthenfinishtheturningwithaHSSsteeltoolifyouwishPlease remember if doing any work that might be

unbalancedstartoffslowlyandincreasethespeedabeltstepatatime

THEACTIONOFCUTTINGTOOLS

Basicallya lathe tool isawedge that is forced into theendofthe rotating bar to remove metal As long as the tool is fedforwardwhilethelatheisrotatingmaterialwillberemovedA typical right-hand turning tool has a cutting angle of 90

degreeslessthesideclearancelessthesiderakeThecuttingangle for this example is 90ndash10ndash10= 70 degrees This is theangle that is wedged into the work to remove the materialSoftermaterialswillhaveasmallercuttinganglewhilehardermaterials will have a larger cutting angle Tool angles varydependingonthetypeofmetalbeingturnedToolsforturningsofter metals usually have higher rake angles than thosedesigned for harder metals since a turning tool will normallyholditsedgeforlongerinsoftermaterialsBrassalthoughsoftusuallyhasnotoprakeonthetoolatallOther angles to be aware of are the top rake and the side

rake

CUTTINGTOOLSHAPES

The followingaresomeof thedifferent shapes thatyoumightfindusefulforgeneralturningandmetalremoval

Right-handknifeturningtoolAllrakeanglesare10degrees

Right-hand knife tool This is used for general turning andfacingofbarstockDependingontheworkyouaredoingyoumayfindaleft-handversionofthistooluseful

Typicalroughingtool

Right-handroughingtoolIthasaleadingangleandasmallradius on the tip of the tool This tool is used for fast metalremovalwherefinishisnottooimportantAgainyoumayfindaleft-handversionusefulAroughingtoolcuttingatanangletoabarwillremoveachip

widerandthinnerthanatoolcuttingat90degreestothebarThis improves tool life although you will have to square theturningupwithastandardknifetool

Typicaldouble-sidedroughingtool

Double-sided roughing tool It can turn towards the left orright It canalsobeusedasaplunge tool to removematerialfroma groove orwhere the component needs to be lsquowaistedrsquodown

Simplepartingofftool

Simple parting off tool This is suitable formostmaterialsYouwillprobablyneedalargeoneforpartingofflargediameterbarsaswellasasmalloneforpartingoffsmallcomponents

Internal(top)andexternal(bottom)screwcuttingtools

ScrewcuttingtoolThisisusedforcuttingscrewthreadsTheanglewilldependonthethreadyouarecutting60degreesformetric55degreesforWhitworthandBSFetc

Shallowboringtoolcapableoffacingacrossthebottomofahole

Boring and facing tool This toolrsquos unusual shape will befound very useful when recessing a large bore It will plungestraight intoasmalldrilledholeandwillalso face rightacrossthebottomoftherecess

Double-endedchamfertoolchamferingadiameter

Double-ended chamfering tool It has 45 degree angles atbothendssoitcanbeusedtochamferexternaldiametersandinternalbores

Double-endedchamfertoolchamferingabore

Othershapescanbeusefulbutthetoolsshownhereshouldbesufficienttogetyougoing

BORINGTOOLS

Boring tools are used to clean up a previously drilled holepossiblytomakeitruntruebutmorelikelytoensuretheholeistothecorrectsizeTheyarenormallylongerthanordinarytoolsandtendtostickoutfurtherfromthetoolholderHSStoolsaresuitableformostusesCarbideinsertedtipboringbarsarealsoreadilyavailableandarethebestbetforturningcastironinthesmallworkshop

HSSboringbar

For really small holes down to2or3mm indiameter solidHSSandcarbideboringbarsarereadilyavailableAlthoughtheyarenotcheaptheywillbefoundveryusefulandquicktouseAnothermethodofboringahole is tousea longseriesslot

drillasaboringtoolInuseclamptheshankinthetoolholderwiththepointatcentreheightmakingsuretherestoftheslotdrillisclearofthesideoftheboreYoucanthenrunitthroughtheboreinasimilarmannertoastandardboringbar

Asmallcarbideboringbarinsertedintoamildsteelshank

PARTINGOFFTOOLS

PartingofftoolsprovideaquickwayofcuttingoffworkfromtheparentbarThereisrarelyanyneedtoworryaboutcuttingthecomponentofftothecorrectlengthtogetagoodfinishAslongasthecomponentislongerthanrequireditcanbeputbackintothe chuck or a collet and the parted off face can be faced tolengthorotherwiseworkedonThepartingofftoolcuttingfacecaneitherbesquareoritcan

beangledtotheleftorright(seepage43)Thesideofthepartingofftoolcouldevenberadiusedsothat

it forms a radius on the end of the next component orchamferedtoformalead-inedgeforthenexttool

CUTTINGLUBRICANTS

Tomake cutting tools cut easily and to prolong their life it issometimesbesttouseacuttinglubricantForsteelIpreferneatcuttingoilItlubricatesbutisnotidealforcoolingtheworkIn industry coolant is normally used This is oil that has an

additivetomakeitsolubleinwaterMostsolubleoilswilldobutthe synthetic ones tend to sting your hands if you have anyopen cuts I would not recommend using soluble oils on thehome workshop lathe as I think they tend to wash thelubricating oil off the slideways and can encourage rustHowever this ismypersonalpreferenceandmanypeopleusesolubleoilinthehomeworkshopwithoutanyproblemsOil is suitable for use when cutting steels mild steels

stainlesssteelsandhighcarbonsteelssuchassilversteelThebestlubricantwhencuttingaluminiumisparaffinItstops

thealuminiumfrombuildinguponthecuttingtoolBrassandcast ironarenormallycutdryWhenturningcast

ironona lathe if the latheisfittedwithasolubleoiltankthecastirondustwillhaveanaffinityforthesolubleoilIfthelatheisthenusedonaluminiumthefreecarboninthecast ironcancontaminatethealuminiumwithblackstreaks

Inormallyplacetheoilorparaffininasmalldish(actuallyacatordogfoodbowl)andapply itbyhandwithasmallbrushThisdoesallIneedThenextchapterlooksatgrindinglathetools

4SharpeningToolsandHoldingThemintheLathe

ThenexttaskistogrindasetofusefullathetoolsThe first thing you will need is an off-hand grinder The

grindercanbeadangerousmachineso itshouldbeusedwithcare Eye protection must be worn the guards should becorrectlyfittedandtheremustbeadequateilluminationIdonrsquotlike using a grinder in a small workshop as the grinding dustflies everywhere and canget onto themachine slideways andtools generally making the workshop dusty and dirty Ifpossible set up thegrinder in a separate areaaway from theworkshopIhavemygrindermountedonafoodchoppingboardso I can carry it outside to use This has the addedbenefit ofdaylight although you are dependent on the weather or youmightneedtouseitafterdark

Theguardofthisoff-handgrinderhasbeenwidenedtoacceptarecessedwheel

GRINDINGWHEELS

IthasalwaysbeenstatedthatyoushouldnevergrindatoolonthesideofthegrindingwheelSofollowingthistheorywewillbeusingarecessedwheelwhereitswidthismuchthickerthanthepartofthewheelusedtoclampthewheeltothegrinderIstruggledtofindarecessedwheelof6in(150mm)diameterandfinally found a 60 grit grinding wheel on a personal visit toAxminster Power Tools in Devon (I could find only an 80 gritwheel in theircatalogue)Thewheels I like touse forgrindingare A60K5V if I can get them and I prefer the white wheelsdesigned for the harder tool steels rather than the grey orbrown wheels which are more suitable for softer mild steelsThedesignationbreaksdown like thisA stands foraluminiumoxide 60 is the grit size K is the hardness (I J and K beingmediumhard)5 is thestructure(thespacebetweengrainsofgrit) and V is for vitrified the method of bonding the grainstogetherTheKandthe5canvaryabiteitherwayandthegrit

shouldbe4660or80with60beingpreferredThe80gritisabitfineandwillclogupquitequicklySo-called green grit wheels made from silicon carbide are

available for sharpening carbide tools They are usually softerthanaluminiumoxidewheelsinordertoallowthegrittobreakdownbeforethewheelbecomesglazedfromgrindingthemuchhardercarbide

Witharecessedwheelyoucancutontheouterfaceoftherecessedsideofthewheel

TestingtheWheel

The first thingyoushoulddowhenbuyingawheel is tomakesurethat it is ratedatasufficientlyhighspeedfor thegrinderon which it is to be used Off-hand grinders usually run ataround2900rpmsoyouwillneedawheelratedtoatleastthatspeed it is all the better if the grinding wheel is rated at ahigher speed than the grinder Care should be taken whenhandlinggrindingwheelsastheyarequitefragileifknockedordropped A grinding wheel should only be purchased from areputableengineeringsupplierSupportyourgrindingwheelona piece of wood and tap the wheel gently with a plasticscrewdriver handle or similar The wheel should lsquoringrsquo if itsoundsdullitshouldbebrokeninhalfandeitherthrownawayorusedontheworkbenchasasharpeningstoneNeverthrowawheelawaywithoutbreaking it into twoyouneverknowwho

mightgettheirhandsonit

Thistoolrestwasdesignedtosharpenplaneironsandchiselsbutitisfineforlathetools

Amoderndigitalanglegaugeisidealforsettingthetoolrest

MountingtheWheel

The wheelrsquos bore should be the same as the spindle of thegrindingwheelOften theborewillbe largerandyouwill then

need some plastic spacers to reduce it Spacers should bereadilyavailable fromyour localengineeringsupplierYoucanturn thespacers fromplastic if youcanrsquotbuyany ready-madeonesAt each side of the wheel you should fit a paper washer

thesearemadeofblottingpapertypematerialandwillprobablyhave been supplied already stuck on the wheel The grindershould have twometal flanges one to fit at each side of thewheel Both flanges should be the same diameter These willhold the wheel true and spread the tightening load on thewheelThegrinderwillhavetwodifferent threadsontheendsof its spindle The right-hand side of the grinder will have aright-hand thread and the left-hand side will have a left-handthreadThedifferentthreadsaretostoptheclampingnutsfromunscrewingwhenthegrinderisrunningTofitthewheelremovetheguardandundothenutRemove

the metal flange and then the wheel Make sure the flangesdonrsquothaveany remainsof theoldpaperwasheron themPutthenewwheelontothegrinderspindle(rememberthespacerthepaperwashersandtheflangesateitherside)andscrewthenuthand-tightFinallyholdthewheelgentlyandgivethenutapinchupwithaspannerYoudonrsquotneedtoover-tightenthenutjustsufficiently tostop thewheel fromcoming looseRefit theguard and spin thewheel by hand to ensure it is not rubbinganywhereNowwearealmost ready to switch thegrinder onBeforedoingsohoweverputonyoureyeprotectionandstandtoonesideofthegrindersoyouarenotinlinewiththewheelshould it burst Then switch the grinder on All should be fineandthewheelshouldberotatingsafely

TOOLREST

Theworkrestsuppliedwithanoff-handgrinderisusuallyjustabitofbentsheetmetalboltedonItisusablebutonlyjustI recently purchased a ready-made tool rest as a basis for

makinganimprovedgrindingrestThiswasoriginallydesigned

forsharpeningplanebladesandchiselsforwoodworkingbutitmakes an ideal rest for sharpening lathe tools It is made ofaluminiumandisfullyadjustableforangleThebestmethodofsetting the rest to the correct angle is to use a digital anglegauge These are now very cheap and are readily obtainableThepositionoftherestinrelationtothegrindingwheelcanbeadjusted on its sliding base Many designs for tool rests havebeenpublishedandyoucouldmakeoneofthoseinsteadifyouwishtosavemoneyThetoolclampassupplied isdesignedtoclampplane irons

andchiselssothisneedstobechangedLathetoolsneedtobepresented to the grinding wheel at the correct angles If youdonrsquot have a digital angle gauge this can be achieved usingsimpleguidesmadefromanglesheetmetalandsomescrewsIused gauge plate made from a high carbon steel with anaccurategroundfinishthatcanbehardenedandtemperedbutmild steel would be perfectly suitable if you donrsquot have anygaugeplateavailableYouwillfindaprotractorusefulyoucangetasteelonewith

an adjustable blade for a reasonable price The protractorwillbeusedtosetthetoolanglethatisgroundonthetools

Sheetmetalprotractorsareavailableverycheaply

LATHETOOLGEOMETRY

LathetoolsneedtobegroundtocertainanglesbuttheanglesdonrsquothavetobeexactFormosttoolssomewherehandywilldounless you are grinding a form tool to a particularly accurateshapeIthasbeennormalforbookstoshowtheanglesontoolsas used in a production environment where tools will ideallyhavealonglifeoftenthislifeiscalculatedaslastinganeight-hourshiftsothetoolonlyhastobesharpenedandresetonceadayInthehomeworkshopwecan increasethesecuttingangles

andgetbettercuttingattheslightexpenseofshortertoollifeWehavealreadyexplainedtheshapesof the tools thatyou

willfindmostusefulToolanglesareknownbytechnicaltermstop rake front rakeside rakeandback rakeThe rakeanglesvary depending on thematerial to bemachined but a set ofstandardtoolswillgetyoustartedSomeoftheaccompanyingphotographsareactuallyoflarge-scalewoodenmodels

Theleft-handtoolissuitableforbothfacingandturningtheright-handtoolissuitableforturningonly

Left-handsideofthefacingandturningtoolshowingthefrontandtoprake

Topofthefacingandturningtoolshowingthefrontandsiderelief

Left-handsideoftheturningtoolshowingthefrontclearanceandthetoprake

Topoftheturningtoolshowingthefrontandsideclearanceandthetoprake

GRINDINGATOOL

WhengrindingHSStoolstrytokeepthemascoolaspossibleIfan HSS tool becomes too hot and is then quenched in waterminutecrackswillformonthecuttingedgesThesecrackswillmakethetoolcuttingedgebreakdownveryquicklywhenusedThe best practice is to grind a little bit off the tool and thenquenchitwhileslightlywarmDonotletthetoolgethotdipitin thewater little andoften This should ensure the tool edgedoesnotbreakdowninuse

GrindingYourFirstTool

Most angles can be ground by using the tilting table whileothersmayneedtobefixedinrelationtotheperipheryofthegrindingwheelThefrontandsideofthetoolcanbegroundbytippingthetableatthecorrectanglewhereasthetoprakecanbegroundontheperipheryofthewheelThegrinder should first be switchedoff andunplugged Set

thetoolresttotherequiredangleusingthedigitalanglegaugeoranangletemplateandtightenuptherestBefore switching on the grinder ensure that everything is

freetorotatebyspinningthegrindingwheelbyhandIf all is well put on your safety glasses and switch on the

grinderPlacethetoolonthetoolrestupagainstthesideoftheprotractor Slide the tool along the table until it reaches thegrindingwheel andmetal starts to be removed Slide the toolbackwards and forwards slowly along the restwhile putting alittle light pressure on the tool so that it continues to pressagainst the grinding wheel When you have removed a smallamountofmaterialcoolthetoolbitdownAtnotimeallowthetool bit to get hot Continue grinding until you have removedsufficientmaterialfromthetoolbit

Thegrindingrestissettothecorrectangleof10degreestogrindtheendofthetool

Grindingthefirstangle

TurnthetooltotheotherangleanddothesamesothatnowboththefrontandsideclearanceangleshavebeengroundThis toolwill be enough for brass but for steelwe need to

grindthetoprakeWhengrindingthetoprakeonaright-handtool the slide rest needs to be higher than the centre of thegrinding wheel so that it grinds the tool at approximately 10degrees

Thefirstanglehasbeenground

You have now ground your first lathe tool The tool asreceivedfromthegrinderwillbetooroughtousehoweversoyouwillneedtohonethecuttingedgesYoucandothisonanoilstone(usedwithfineoillike3in1)orwithadiamondlaporusing a combination of the two Lightly lap the front and sideclearanceanglesuntilyougetagoodfinishand lightlyhoneaverysmallradiusonthetipofthetoolFinallyhonethetoprakeangleandyourtoolisreadyforuse

Grindingthesecondangle

Thesecondanglehasbeenground

AllofyourHSSturningtoolscanbedoneinthiswayOnlytheangleswillvaryandthesecanbesetusingadigitalanglegaugeandprotractorAnoccasionalhonewillresharpenyourtoolsaslongasyoutreatthemwithcareA similar range of HSS tools and a parting off tool all with

zero top rake shouldbeavailable if youwill be turningbrassUnless you are doing quantity production one tool holdershouldbesufficientforbrassAsatoolforbrasshasnotoprakeandyouwouldnotnormallygrindthetopawayaslongasyoubuy tool steel of the same size the tip height will remain thesameYoucanthenusethedifferenttoolsinoneholderwithouthavingtoresettheheight

MACHININGCASTIRON

Carbide-tippedtoolsareidealformachiningcastironAsimplebrazedupcrankedtoolwithasmallchamferonthenosewilldoforbothturningandfacingcastironcomponentsThemainuseof this tool will however probably be truing up the faceplatethat comes with the lathe The large diameter combined withtheintermittentcutovertheboltgrooveswoulddestroyanHSStoolinafewsecondsAsmalltippedboringbarwillbeidealfor

taskslikeboringcastironcylinders

Grindingthethirdangle

Asimplediamondlap

Thethirdanglehasbeenground

Tosharpentippedtoolsyouneedadiamondwheelorifyouwant to remove large amounts of carbide a silicon carbidewheeloftencalledagreengritwheelowingtoitsusualcolourSilicon carbide wheels are much softer than aluminium oxidewheels as they need to break down faster to present newsharpergrainstothecarbidetoolAdiamondwheelisonlydesignedtolightlylapatippedtool

itisnotsuitableforremovinglargeamountsofcarbide

Diamondcupwheel

TOOLHOLDING

Smallerlathessuchasarefoundinmostworkshopsmayhaveatopslidewithatoolclampforindividualtoolsablockwithasingle slot to take the tool a four-way turret (or sometimes athree-way)oraquick-changetoolblockandholdersetThereisalsotheso-calledAmericantoolpostwhichisaroundbarwitha slot through it and a bolt in the top to clamp the tool ItusuallycomeswithmatchingdishedwasherstoadjustthetoolheightThistypeisnolongerverycommononlathes

Quick-changeToolPost

Themostversatiletoolholdingsystemisthequick-changetoolblockwithmatchingholdersThedrawbackwiththissystemisthe cost of extra tool holders you need quite a few one foreachtoolThequick-changetoolblockmountsonthefrontofthelathe

normallyontopofthetopslide(Blockscanbefitteddirectlyon

thecrossslidebytheuseofaraisingblocktoaidrigidity)

Quick-changetoolblock

Each holder is set up with its own particular tool The toolholderscanbe individuallysetso that the turning tool isdeadoncentreheightandispresentedcorrectlytotheworkpiece

Quick-changetoolholder

Quick-change tool holders are available with a straight cutslottotakestandardsquareshanktoolholderswithastraightcutwiththeadditionofaVeecut-outinthebottomforusewithroundtoolssuchasboringbarsandasafrontpartingoff tool

holdertotakeahighspeedsteelpartingoffbladeRearpartingoff tool holders are available to take an inverted parting offbladeeitherahighspeedsteelbladeoran insertedtipbladeLeft-handed and right-handed extended tool holders are alsoavailableandmayoccasionallybequiteusefulThetoolblock isnormallymountedonthetopslidebutyou

cangetraisingblockstouseinsteadofthetopslideThismakesthetoolholderblockmuchmorerigidAbackquick-changetoolblockwillneedmountingonaraisingblock

Backofaquick-changetoolholdershowingthedovetailtypeofmounting

Right-handandleft-handextendedtoolholders

StandardtoolholderwithaVeetotakeroundtoolholders

Frontpartingofftoolholder

ToolClamp

Satisfactoryworkcanbedonewithatoolclampedontothetopslideusingshimsteel toset thecentreheightof the toolThemaindrawbacksarethatyoulosethepositionofthetoolwhenyoutakeitoffthetopslidetofitthenexttoolandyoualsolosetheaccuratecentreheightofthetoolunlessyoukeepthetoolandshimstogetherIfyouaremakingonlyonecomponentthisisnotaproblembutitisanuisanceifyouaremakingabatchofmatchingcomponents

Simpletoolclamp

Single-slotBlockToolPost

AblocktoolpostisoftensuppliedwiththecheaperlathesThetoolpostisliterallyablockofmetalwithaslotcutinittotakethe turning tool It is relatively easy to set the tool up at thecorrectcentreheightbyusingvariousthicknessesofshimThisisfineforthebeginnertoturningwhoisjuststartingoutbutitisbesttoreplaceitwithafour-waytoolpostoraquick-changetool post You could of coursemake several block tool postsandkeepeachonesetwithadifferenttool

Four-waytoolpost

Backtoolpost

Four-wayToolPost

Four-wayToolPost

Thefour-waytoolpost isagoodcompromiseona latheasyoucansetfourtoolsintheturretandrotateeachoneintopositionas needed This speeds up production and is a lot faster thanusingasimpletoolclampThedrawback isthatthetoolsstickoutof the turret fourdifferentwaysandyoumightcatchyourhandonasharp toolAsimple ratchetstopensures thateachtool repeats its position when the tool post is rotated so theworkisaccuratelyturnedeachtimethetoolisusedAduplicatefour-waytoolpostwithtoolsforbrasswillspeedupproductionevenmoreCastingsareavailabletomakeyourownthree-waytoolpost The three-way toolposthas theadvantageofbeingable to get close to the work when you are turning betweencentresFor the front tool post I would recommend right-hand and

left-hand roughing tools right-hand and left-hand finishingtools a tool groundup to face barswhile using a half centreand a Mini Thin inserted tip grooving tool with grooving andparting off inserts You will also need large and small boringbarsbothHSSandwithinsertedtipsTheHSStoolsshouldbegroundupforuseasgeneral-purposeturningtoolsformildsteelandsimilarmaterialsThecarbideinsertedtipboringbarshouldbefineforcastiron

BackToolPost

You can fit a quick-change tool block to theback of the crossslideaswellasthefrontSpecialholdersareavailabletotakeaHSSparting off blade or an inserted tip parting off blade Thebladewill be angleddown to give top clearancewhenpartingoffTheseback-mountedtoolblocksareveryhandyastheycanalsobefittedintotoolholderswithafacingtoolorachamferingtoolFor a back tool holder set-up I would recommend an HSS

partingoffbladeafacingtoolforcastironandadouble-ended45-degree chamfering tool that can be mounted parallel with

the chuck or at 90 degrees to it This set-upwill allow you tofaceaworkpiecechamfertheoutsidediameterandortheboreandpartitofftolengthThenextchapterlooksatholdingworkinachuck

5WorkholdingintheChuck

This chapter covers the different types of chucks how to usethemandsetupworkinthemaccurately

Aself-centringthree-jawchuckfittedwithlsquodrilljawsrsquoNotetheexternaljawswhichareinterchangeablewiththedrilljaws

USINGCHUCKS

Themostusefultoolsforworkholdinginthelathearethree-andfour-jaw chucks The three-jaw chuck is usually of the self-centringvarietythistypeofchuckcomesasstandardwithtwosets of jaws The first set of jaws are known as inside or drilljaws as they are most useful for holding round and hexagonbarsTheother setof jawsareoutside jawswhichholdworkusuallyindiscformontheoutsideSelf-centringmeansthatwhenyouinsertabitofbarintothe

chuck and turn the chuck key the chuck centralizes theworkpieceas it tightensup It isunlikely to runperfectly truebutitshouldruntruewithin3or4thouYou can also purchase soft jawswhich are exactly as their

namesuggestsYoucan thenbore themout to fit thework Ifyouborethemonthelatheyouaregoingtousethemontheworkwillrundeadtrue

Asetofsoftjawscanbeturnedorboredtosuittheworktobeheld

Aself-centringfour-jawchuckThesealsocomewithexternaljawsandsoftjawsareusuallyavailable

Self-centring four-jaw chucks can be used for square barsTheyarealsousefulforholdingroundbarswithmoregripthanathree-jawself-centringchuckSoft jawsarealsoavailableforfour-jawself-centringchucks

Afour-jawindependentchuck

Youare howevermuchmore likely to comeacross a four-jaw independent chuck than a four-jaw self-centring chuckIndependent means that the jaws can be moved individuallyand the jaws can also be reversed one two three or four ofthemdependingontheworktobedone

Abaseplatecastinginafour-jawindependentchuck

Wewillfirstlookatthethree-jawchuckThebestmethodofmaking a component in one of these is if possible to turn itcompletely at one set-up If you put a piece of bar into thechuck face the end centre drill drill and ream it skim thediameterandpartitoffitshouldbeconcentricalloverThisisbecausewehaveturneditallatthesamesettingwithouttakingit out of the chuck If we need to machine the other endhoweverwhenwe turn it roundandput it back in the chuckthechancesareitwillnotruntrueThis iswherethe four-jaw independentchuckcomes inYou

canput thecomponent intoa four-jawchuckandset it to runtrueusingthedialtestindicatorAnyworkyoudoonthepartedoff end should then be concentric with the rest of thecomponentWhensettingworkinafour-jawindependentchuckfor a second operation use some thin shimbetween the jawsandtheworkpiecetoavoidmarkingtheworkWorkisoftenheldinafour-jawchuckbecauseitisacasting

anoddshapeorsquareandsowonrsquotfitintoathree-jawchuckIf thework just requires tobe faced flat rightacross the facethereisnoneedtosettheworkrunningradiallytrueItshouldbe near enough on the centre line as long as the work is

reasonablybalancedYou could of course put the component into a three-jaw

chuckbyfittingsoft jawsandmachiningorboringthemouttotake the component This is the best option ifmaking severalcomponentsthatneedtobeidenticalbutifyouonlyneedoneor two components a four-jaw independent chuck will be thequickestmethodofmachiningthemLargerdiameterscanbeheld ina three-jawchuckbyusing

theoutsidejawsThesehavealargeradiusontheinsideofthejaw ifthisradiusis largerthantheworkpiecethejawsshouldnot tend to dig into the work and mark it Outside jaws areuseful forholding components like small flywheels locomotivewheels and chuck backplates when machining the bores ofholesorwhenmachiningacrossthefaceWhenmachining thindiscs it isuseful toputsomepacking

behindthedisctomakeitstandproudofthejawsTostopthepackingflyingoutwhenthemachineisrunningmakeasetofthree or four packing pieceswith grooves at each end and fittensionspringstothemTheyshouldallbethesamediametersothatthebackoftheworkisparalleltothechuckThelengthand grooves can vary slightly as they donrsquot affect theparallelismTheyarequickandsimpletomakesoacoupleofsets of different diameters should find their way intoeverybodyrsquostoolbox

AlthoughmostlathechuckkeyshavesquareendstheyareoftenofdifferentsizesKeepeachkeywithitsownchuck

ChuckKeys

I have alreadymentioned that the chuck key should never beleftinthechuckwhenitisunattended(seeChapter2)PutthekeyintothechuckuseitandputitsafelyawayassoonasyouhavefinishedwithitIfyouswitchonthelathewiththekeystillinthechuckyoumightneedatriptothehospitalDonotuseexcessive forcewhenyou tightenup the chuck

Do not use a piece of tube a spanner or anything else as alever thechuckkeyon itsownshouldbesufficient to tightenthechuckontotheworkWhenusinga four-jawchuckasmallchuckkey littlemore

thanaknurledknobwithasquareoncanbeusedtoadjustthejawsinandoutpriortotighteningupwiththeproperchuckkeyThiswill save timeover adjusting the jawswith a large chuckkeyTo turn the independent four-jaw chuck jaws round a

carpenterrsquosbracewithapieceofsquarebarinittofitthechuckwillmakeshortworkofreversingthe jawsbutdonrsquotuse it forthefinaltighteningasitisliabletostrainthejaws

STARTINGTOTURN

Before going any further you need to learn how to do basicturningFor thisyouneed toput the three-jawchuckonto themandrelStartbycleaningthemandrelwithacleanbitofragorsimilar(Ikeeparollofpaperkitchentowellingintheworkshop)Nowyouneed toclean thechuckrsquosboreand threadusing thetwotoothbrushmethod(seeChapter2)BoththemandrelandthechuckshouldbecleanbeforeyouattempttofitthechucktothelatheSelecting and grinding turning tools has already been

discussed (see Chapter 4) so by now you should have acorrectlygroundturningtoolsuitableforroughingoutapieceofsteelbar

Barwithapiptoolaboveorbelowcentreheight

MakingaToolCentreHeightSettingGauge

Thistoolneeds itscuttingedgesettothecentreheightofthelatheThereareseveralwaystodothisbutoneoftheeasiestiswith a home-made height gaugeWhen starting out this is achickenandeggsituationyouneedtomakethegaugetosettheheightbutyoualsoneedatoolsetatthecorrectheighttomakethegaugeThesimplestwaytoovercomethisproblemistosetthelathe

tooltotheapproximatecentreheightandtakeacutacrossthefaceofthebarDependingonwhetherthereisapipremainingon theendof thebaryoushouldgetan ideahow farout thetoolheightisIfthereisnopipthismeansthetoolisoncorrectcentre height or too high A pipmeans the tool is too lowOfcourse you may have been lucky so try dropping the toolslightly until a pip remains You can then raise the tool a fewthouatatimeuntilthepipdisappearsThetoolshouldthenbeoncentreheight

Barwithnopiptooloncentre

Nowthatthetoolisatcentreheightyoucanmakeasimpleheight gauge Turn a piece of bar down to as close to frac12in(12mm)asyoucangetandleaveitinthelathechuckMeasurefromthetopofthecrossslidetothetopofthebarwithacheapheightgaugeLowertheheightgaugebyhalfthebardiameterTheheight

gaugeshouldbeexactlyonthelathecentrelineMakeanoteofthisdimensionWe now need to look at how to turn a bit of bar to an

accuratediameterWhenturningabartosayfrac12in(12mm)youneedtostartwithsomethingslightlylargerInthiscasethiswillbe⅝in(16mm)diametermaterialasthisisastandardsizeCutapieceofmaterialabout2in(50mm)longandputitinto

thechuckwithabout1in(25mm)stickingoutSkimtheoutsidedown to about 0510 thou or 1225mm which is 10 thou(025mm) above the size required (You should be aware thatmosthobbylathedialsremovetwicewhattheysayaonethoudivisionforexamplewillusuallytake2thoufromthediameterLargercommercial lathesaremuchmore likelytotakeoffonethoupergraduation)Nowtakesmallcutsuntilalmosttosizeusingpowerfeedif

you have it andmaking sure you knock the feed off before ithitsthechuckStopthelatheandwindthecarriagetothestart

of the bar Take another cut at the same setting andmake anoteofthediameterTakeanothershallowcutbutthistimegoonly about frac14in (6mm) along the bar knock the feed off andturn the lathe off Move the carriage towards the tailstock sothat you can measure the bar Continue making this cut andmeasureuntilthesizeiscorrectThenrunthetoolalongthefulllengthof the jobWindthecarriagebacktowardsthetailstockand take a finishing cut or two at the same setting ThediametershouldnowbetheexactsizerequiredIt is not difficult to turn accurately it just takes a little

patienceandpracticeThemoreturningyoudotheeasieryouwill find it is to hold accurate limits If you turn everythingaccuratelywhetheritneedstobeaccurateornotyouwillsoonlearntoturnwithinathouorsowithoutanyproblems

Measuringtheheightofthebarabovethecrossslide

Now we need to make a tool height setting gauge Cut alengthofbarjustoverthedimensionsyouwrotedownandfaceone end turn it round in the chuck and face the other endMeasurethelengthandfindouthowmuchyouhavetotakeoffit to give the dimension you want Put the bar back into thechuck and bring the tool up to the face of the bar Lock thecrossslideFacethebartolengthbyusingthetopslideindexmovingforwardsafewthouatatimeuntiltherequiredlength

is reached Younowhavea tool height settinggauge suitableforthefrontandreartoolsIf you have an inverted Vee bed lathe or if for any reason

youcanrsquotusetheheightgaugeflatonthebedyoucanputtheheightgaugeonaplateon topof the lathebedwhileyouaresettingthetoolheight

Settingtheheightgaugetothelathecentreheight

Settingtheheightofthetool

Usingthesettinggaugetosettheheightofthereartool

TurningtoaSpecificLengthandDiameter

Nowwewill turnabarwithastepon theendToensure thatthestep isthecorrect lengthwewilluseabedstopThiscanbe as simple as a block clamped to the lathe bed to stop thecarriage moving any further I use a simple home-made bedstopthatdoesallIrequireSetthebedstopthenmovethecarriageuntilittouchesthe

stop and lock it Wind the top slide so that the tool is justtouching the end of the bar and lock the carriage For thisexercise we will make the step 16mm long and 12mm indiameterWindthetopslidealong159mmWecannowroughout thestepateachendTurn theenddown toabout02mmabove the finisheddiameterbywinding thecarriagebackandforthYoucanusethe fine feedbutmakesureyouknockthefeed off before the carriage reaches the stop and finish up tothestopbyhandWindthetopslidealongtheremaining01mmto12mmandfinishthediametertosizeandlengthtakinglightcuts as previously Donrsquot forget to clean up the face of theshoulderyouhavejustturnedIfyouneedtouseabedstopatthetailstockendofthelathe

asimplemethodofdoingthisistouseabarplacedonthelathe

bed against the tailstock The bar acts as a stop when thecarriageiswoundbacktowardsthetailstockThistailstockendbed stop is useful when you are turning a groove in acomponentandyouneedstopssetatboth theheadstockandtailstockendsofthelathe

Ahome-madebedstop

TurningWorkontheOutsideoftheInsideJaws

Theoutsideoftheinside(drill)jawsareusefulforturninglargerdiameterwork that is too large to fit inside thedrill jawsThiswillmostoftenbe in the formofa flywheelcastingFlywheelswithsixspokesareidealforturninginathree-jawchuckasthespokes can fit between the chuck jaws Ideally you need totighten up the flywheel until it is tight but not so tight as todistorttherim

TurningasteponabarusingthestopThebarisheldinthethree-jawchuckandsupportedwiththetailstockcentre

Ausefultailstockendbackstopmethod

Holdingaflywheelinathree-jawchuck

Holdingaflywheelintheoutsidejaws

To ensure concentricity you should do as much work aspossibleonthecastingatthesametimeYoushouldbeabletoturntheoutsiderimofthecastingfacetherimfacethebossand drill bore and ream for the crankshaft all at the samesettingAllyouneedtodothenistofittheoutsidejawsreversethecastinginthechucktapitgentlybackontothestepsoftheoutsidejawsandfaceacrossthesecondsideoftherimandthehubUseabitofshimtoprotecttheflywheeldiameterItdoesnotmatter if the flywheel runs exactly true or not as you areonlyfacingitparallelandtowidthnotturninganydiametersto

size

UsingtheSoftJaws

Soft jaws are very useful when a component has to run deadtrue in the jaws for example when making something like agrindingspindlewhereconcentricityisimportantSoftjawslikelytobefoundinthehomeworkshoparesimple

rectangles of steel with the scroll and groove formed directlyintothesoftjawsAnothertypeofjawyoumaycomeacrosshasa grooved pattern in the main jaws that matches a similarpattern in theactualsoft jawsThesoft topsof these jawsareusually interchangeable They are more likely to be found onlarger chucks but you could make your own version for thesmallersizesofchuckifyouwishThemain use of soft jaws is for second operationwork for

examplewhenyouhaveturnedacomponentcomplete fromabitofbarandparteditoffNowyouneedtoholdthecomponenttruetofinishoffthesecondendYoucandothisbyboringoutthechuckjawstotheexactdiameteroftheworkpieceToborethesoft jawstheyshouldbetightened inthesame

direction as they will be tightened in use so that they areoperatingonthesamepartofthechuckscrolleverytimeIfyouhaveathincomponenttomachinefitthesoftjawstothechuckandtightenthejawsontoabitofbarheldinthechuckBesureto leaveenoughspace in frontof thebarsoyoucanbore thejawstofitthework

BoringsoftjawstofittheworkThejawsareclosedontoanoddmentofbartoturntheshallowregistersothatittakesthework

AlwaysusethesamechuckkeyholewhentighteningupthejawsThisappliestoanythingyoudowithaself-centringchuckStampacrossoracentrepopmarkagainstoneof the jaws IsuggestdoingthisnexttojawNo1butanyonewilldoaslongas you always use the samemarked hole Youmight as wellmarkallyourself-centringchucksinthesamemannerCarefullyborethejawstotheexactdiameteroftheworkto

be machined Try to get it exactly on size Undo the jawsslightly remove the bar and replace it with the workpiecewhichshouldnowrundeadtrueAusefulmodificationtothesoftjawsistodrillandtapahole

inthemiddleofthejawsandfitanAllenscrewtoeachholeIfyouwant toholda longbar in thesoft jaws it isnoweasy toboreallthewaythroughthejawsratherthanjustboringastepor part way through All you need to do now is find a disc ofmaterial to put into the chuck ensuring there is sufficientmaterialleftontheinsideedgesofthechuckjawstoborerightthroughtotakethebar

Holdthedisconthescrewheads ifnecessarydrillthediscbeforeboringBorerightthroughthediscandthejawsuntilyouarenearlytosizeatwhichpointyoucanborethroughthediscand test the resultingborewith theworkpieceMakesureyouclean the bore thoroughly before trying the workpiece sinceloose dust can make the hole seem smaller than it really isWhentheworkpieceenterstheborefinishboringrightthroughthe jawsgo througha coupleof timesat the samesetting totakeoutanyspringintheboringbarYoucannowremovethedisc clean the jaws and put the workpiece right through thechuckcheckingthatitrunsdeadtrueThisoperationmaysoundtimeconsumingforasingle item

but if you have several components to make it will save aconsiderable time on setting up each bar individually to runtrue

BoringsoftjawsusingaringThesoftjawshavethreeAllenscrewsthatarecloseddownontotheringwhileboring

TurningtheoutsideofthesoftjawsusingaringThesoftjawshavethreeAllenscrewsthatareopenedupontotheringwhileturning

NowthescrewsareinplacewecanworktheotherwayroundandholdcomponentsontheoutsideofthejawsTodothisyouwillneedaringofasuitablesizeontowhichyoucantightenthejawswith the jaw loading acting outwards so any componentyouputontheoutsideofthejawswillberunningconcentricallyThiswill be ideal for itemssuchas tractionenginewheel rimsandotherlargehollowortubularworkpiecesOne other use for soft jaws is to hold irregular-shaped

components Put a piece of bar into the soft jaws and bore aholeofanysizeand thencleanup theboreso thatallof thejawsare true Transfer the chuck to themillingmachine tableandclampitdownUseatestindicatortocheckthattheholeinthechuckistrueYou can now mill a nest to take any irregularly shaped

component confident that when the chuck is returned to thelatheitwillberunningtrue

Plungertypedialtestindicator

Levertypedialtestindicator

DialTestIndicators

Therearetwomaintypesofdialtestindicatortheplungertypedial test indicator as its name suggests works on a plungerprinciplewhilethelevertypedialtestindicatorhasastylusonthe end The lever stylus is usually ball-or pear-shaped and isfixedtothedialtestindicatorwithafrictionfitmeaningthatitcanbemovedupanddownontheendofthedialtestindicator

throughawidearctoputitintothebestpositionforuseThe plunger type dial indicator usually has a maximum

plungermovementoffrac12in (12mm)butplungermovementsofupto2in(50mm)areavailableTheplungertypedialindicatoris non-reversing and needs an adaptor to enable it to clockholes true Instead of a stylus it has an interchangeable endoften with a ball fitted various interchangeable ends areavailableoryoucanmakeyourownThe lever dial test indicator has a much smaller range of

travelarangeof0008in(02mm)isverycommonItisusuallyeither self-reversing (itmoveswhen in contact with theworkdependingonwhichwayitismoving)oritmaybereversedbyusinga lever on the sideof thedial test indicator both typesarequite commonSince the stylus isdelicate combinedwithitslimitedtravelrangeyoumustbeverycarefulnottobreakitAplungerdialindicatorcanbeusedasadirectreadoutofthe

travel and will be found to be very accurate Owing to therelativelylongtravelifyouwantedperhapstooffsetthecentreofabitofbar in the four-jawchuckby0125in (318mm) thiscanbedonebyturningthechuckbyhandandsettingthebaruntil the indicator travel shows 0250in (635mm) which is0125in (318mm) offset The lever dial test indicator is of nouseforgivingdirectreadingslikethisbutshouldbeusedasacomparatorwherethereadingtakenisforexamplezeroatallpointsofthetravelThedial test indicator is usuallymounted on amagnetic or

vacuum base but is sometimes fixed to a block that can beclampedtothelathemostoftenonthecrossslideSometimesthedialtestindicatorcomesasacompletekitincludingvariousmountingcomponents

Clockingtheendofacastinginafour-jawchuck

Four-jawChuck

To set thework up in an independent four-jaw chuckwe firstneed to know what part of the workpiece should be on thecentre If theworkpiece is a castingwemay have an outsidediameter or a hole that needs to run true in this case wewould put a dial test indicator onto the work and adjust thechuckalittleatatimeuntilthediameterrunstrueDonotturnthe chuck with the indicator in the hole Instead wind thecarriage forwards until the clock enters the hole and take areadingWind thecarriageback rotate thechuck90degreeswindthecarriageforwardandtakeanotherreadingAdjusttheworkinthechuckuntilitrunstrue

WhereacastingisstickingoutashereyoushouldtrytosupportthecastingwitharunningcentreThiswillhelptostopthecastingshiftinginthechuck

LatheCentreFinder

If there isnodiameterorholeyoumayhave tomarkout thecentreontheworkusingaheightgaugeandcentrepopitwithacentrepunchThenyoucanuseawobblerandatestindicatortosettheworktrueItwasoncepossibletogetalathecentrefinderconsistingof

a bar about 6in (150mm) long pointed at both ends with auniversaljointabout1in(25mm)fromthefrontendInusetheshortfrontendgoesinthecentrepopoftheworkinthechuckWhen you rotate the chuck by hand the pointed short endfollows the eccentricity of the centre hole which ismagnifiedaboutsixtimesatthetailstockendYouthenjusthavetoadjustthechuckuntilthetailstockendisrunningtrueatwhichpointthe centre in the work will also be running dead true I donrsquotknow anyone who makes these and second-hand ones areextremelyrare

Asimplehome-madecentrefinder

You can make a simple version of this that works well byusingamillingmachinepointedcentrefinderThisisaparallelbarwithaseparatemoveablepointedendThetwocomponentsare held together with a spring inside You need the pointededge finder a Morse taper parallel adaptor (the Morse tapershould fityour tailstock)aspringandashortstubofbar thatwillfitinsidethetaperedholderrsquosboretostopthespringgoingrightthroughPuttheshortstubofbarintothetaperinsertthespring follow up with the centre and put the Morse taperadaptorintothetailstockBringthetailstocktowardsthechuckuntil the centre of the centre finder is in the centre pop ThespringwillholditinplaceTousetheimprovisedcentrefinderput a dial test indicator onto the parallel part of the centrefinderrsquospointandrotatethechuckbyhandThepointwillrotateeccentricallyadjust thechuckuntil thecentre finderrsquospoint isrunningtrue

Usingascribingblockwithadialtestindicator

Move the tailstock along the bed until the point of thewobblerisinthecentrepopontheworkPutthetestindicatoronthefrontdiameterofthewobblerandadjustthechuckjawsuntilthewobblerisrunningtrueWhensettingupacastingorsomethingsimilarwherenotall

of the diameters are machined you should use the dial testindicator on diameters thatwill not bemachined such as theinsideofaflywheelrimWhenyouhaveturnedallthefinisheddiameters they should then be true with the unmachineddiametersSetting work in the four-jaw chuck depends on the

componenttobemachinedIfyouareusingroundmaterialyoucansetittoruntrueusingadialtestindicatorHoweverifyouaresettingaroughcastingthevariationofsizeandroughnessofthecastingsmaywellbeunsuitableforadialtestindicatorThere are alternativemethods of settingwork up in a four-

jawchuckespeciallyforcastingsOneofthesimplestmethodsis toholdasquarebar in the lathetoolholderandusethis tosetthejobtrueInuseyouwindthebaruptotheworkandsetthedial tozeroorotherwisemakeanoteofwhere it isWindthebaroutorawayfromtheworkTurnthechuck180degreesand wind the bar up against the work again You can

immediatelyseewhichwaythebarneedstomovesothatitisrunningtrueAdjustthecastinginthefour-jawchuckandmovethecastingtowardsthecentrepointRepeatuntilthecastingisrunning true This method is also useful if you are setting asquarebar to run true Justcheckeach faceof thesquarebarwiththebitofmetal

Settingacastingbyusingasquarebar

StickyPinMethod

An alternative the sticky pin method is especially suited tolocomotive wheels or flywheels An ordinary household pin ismounted in plasticine or Blu-tack perhaps stuck on the lathetool and is arranged to point to the inside diameter of thewheelor flywheel thearea that isnotmachinedbut is leftascastAdjustthecastinguntiltheunmachinedfaceisrunningastrueasyoucangetitandthewheelisreadytoturnThestickypinmethodisalsousefulforsettingupworkthathasachuckingspigot such as a locomotive smokebox door Just hold thechucking spigot in the four-jaw chuck and adjust the castinguntilitrunstrueontheoutsidediameterandthefrontface

Usingacommercialstickypintosetworktrue

Themethodsofcentringworkinthefour-jawchuckthathavebeen discussed are also suitable for setting work true on thefaceplate The next chapter looks at turning between centresandusingthefaceplate

6TurningbetweenCentresandFaceplateWork

Thischapterdealswithbasicturningbetweencentresandthenintroduces turning with the work mounted on the lathefaceplate

Headstockcentreanddriverplate(alsoknownasacatchplate)

TURNINGPLAINBARSBETWEENCENTRES

The most basic way of holding work for turning is between

centres Turning between centres is literally holding thecomponenttobemachinedbetweentwocentreseachofwhichhas a 60-degree included angle The headstock centre usuallygoes round with the headstockmandrel although some olderlatheshadanon-rotatingcentreandthedrivetotheworkwasbyapulleymountedontheworkThetailstockcentreisoftenafixedcentrethatdoesnotgoroundalthoughcentreswithballbearingscalledrunningcentresarereadilyavailable

Tailstockplaincentre

The component to be turned usually a shaft has a female60-degreecentreinbothendsthatisusedtosupporttheworkThe work can be turned round between centres so that bothends of the shaft can be machined Because the work ismountedbetweencentresbothendsoftheworkwillbetruetoeachother

Tailstockrunningcentreso-calledbecauseitrunsonballraces

CentringtheBar

FirstwehavetoputthecentresintoeachendofthebarIfthebarisshortsayuptoabout6inlongholdtheworkinthethree-jawchuckanduseacentredrillinthetailstockdrillchucktoputacentre intothebarAcentredrill isashortdrillwithasmallpilot on the end that has a 60-degree taper to the bodydiameterAbettermethodof centring thebar especially longbars is by using a three-jaw chuck and the fixed steady Thebarisheldinthethree-jawchuckwiththeotherendsupportedin the fixedsteadyand thecentre is formed in theendwithacentredrillAusefultoolthatcanbeusedtofindthecentreoftheshaftis

thecentresquarewhichisametalbladewithaVeeonitthatlocatesonthediameterofthebarMarkalineacrosstheendofthebarwitha scriber turn the centre square90degreesandthenscribeanotherlineWherethetwolinescrossisthecentreof thebar Tomake it easier to see the scribed linesblackenthe end of the bar with a permanent felt tip marker beforescribingCentrepunchthepointwherethetwolinescrossandput a 60-degree centre in each end of the bar using a centre

drill in a power drillHold thebar in a bench vicewhile doingthisPutacentredrillintothetailstockdrillchuckandinsertthebar in the three-jaw chuck Make sure the lathe is on a lowspeedabout300rpmwindthetailstockinandjustlightlycleanupthecentreholewiththecentredrilltotrueitupAnotherusefultooltofindthecentreofabarisabellcentre

punchThiscomprisesaconewithacentrepunchinthemiddleIn use place the bell end on the end of the bar and tap thecentrepunchwithahammertomarkthecentreTheendofthebar though needs to be reasonably square if using the bellpunchmethodThere are other similarmethods of centring bars but those

givenherewillbealltheturnerneedstolearn

Turningbetweencentres

Centringthebarusingthefixedsteady(Notethatthefrontclampisnormallydoneupwhileinuse)

Asimplecentresquare

Crosssectionofbellcentrepunch

MachiningtheBar

NowweneedtomountthebarbetweencentresThisissimplyamatterofputtingthebarbetweencentresandtighteningthetailstocksoitislightlypressingintothecentreintheendofthework To drive the work a carrier is fixed to the shaft andengagesapininacatchplatemountedonthelathemandrelAcatchplateissimplyablankdiscwithapinstickingouttodrivethecarrierthat isfittedtotheworkThecarrier isfittedtotheworkusinganAllenscreworboltTostopanymovementofthebarinrelationtothecatchplatethecarriercanbewiredtothecatchplatepinThiswill stop thecarrierand thework flappingaboutItisparticularlyimportanttostoptheworkfrommovingin relation to the catchplate when screwcutting betweencentres

Facingoffabarusingthehalfcentre

Nowthatthebarissafelymountedbetweencentreswecanstart turning it tosizeNormally the first thing todo is to facetheendsofthebartothefinishedlengthDecidewhichendofthebarhastheshallowercentreWewillmachinethisendfirstYouwillneedahalfcentreso-calledbecausealmosthalfofthecentre is missing This means the lathe tool can reach rightacrosstheendoftheworkwithouttouchingthehalfcentreWhenusinganyfixedcentreinthetailstockputabitofoilor

grease into the centre before use and top up as necessaryLightlywindthetailstockbarrelagainstthecentreandlockthebarrel so it canrsquotmoveSwitch the latheonandwind the toolacross to clean up the end Reverse the work and clean theotherendupat thesamesettingBothcentresshouldnowbethesamedepthMeasuretheoveralllengthofthebarTakethefinished length required from the overall measurement youhavejustmeasuredDividethisbytwoandthisishowmuchweneed to take off each end of the shaft so it finishes at therequiredlength

Askimmedbar

Ifyouhaveonechangethetailstockhalfcentretoarunningcentre if you donrsquot have a running centre change to a fixedcentreThehalfcentreshouldonlybeusedwhenfacingtheend

of the bar We will nowmachine the rest of the bar For thepurposeofthisexamplewewillassumethebarhasafinisheddiameter in themiddle with a step at each end First we willmachine the overall diameter to size To do this we need toskimthediameterandcheckthesizeTakeafinecutalongthebarusingthefinefeedifyouhaveoneMeasurebothendsofthebar Ifyouhavesetthelatheupcorrectly(seeChapter2)thebarshouldbeparallelIfitisnotadjustthetailstockbeforecontinuingAssumingthebarisparalleltakeanothercutortwosothatyouareabout01mmlargerthanthefinisheddiameterNowmove the tool in until almost at finished size and take alight cut about 10mm long along the bar Repeat this cut toensure the tool is notpushingoffMeasure thisdiameter youwill probablyhave towind the tailstockbarrel back toget themicrometerontotheendofthebarOnlymovethebarrelbackdo not slide the entire tailstock backMeasure the bar to findouthowmuchtoremovefromthediameterTakeanothershortcutandcheckforsizeWhenthebariscuttingtosizemachineall thewayalongYouwillprobablyhave to take twoor threecuts at the same setting until the bar ismachined to finishedsizeNowwewill turn the stepson theends Toensure that the

stepsare thecorrect lengthwewilluse thebedstopSet thebedstopthenwindthetopslidesothatthetoolisjusttouchingthe end of the bar For this exercise we will make the steps12mm long Wind the top slide along until the tool is justtouching the end of the turned bar Wind the top slide along119mmWecannowroughoutthestepateachendTurntheenddowntoabout02mmabovethefinisheddiameterYoucanusethefinefeedbutmakesureyouknockthefeedoffbeforethecarriagereachesthestopandfinishuptotheendbyhandRepeat for the other end Wind the top slide along theremaining01mmto12mmandfinisheachendinthesamewayasyoufinishedthemaindiameterDonrsquotforgettocleanupthefaceoftheshoulderyouhavejustturnedCongratulations you have just turned an accurate shaft

Donrsquotworryiftheshaftisatinybitundersizeyoucanprobably

makethematingholestofit

Thefinishedshaft

Usingachuckandarunningcentre

Usingthemethodsetoutaboveyoushouldnowbeabletoturn any shaft you require within the capacity of the lathe Avariationoftheabovemethodwheretheshaftissingle-endedistoholdoneendinthethree-orfour-jawchuckandsupporttheotherendwithacentreinthetailstock

Alargefaceplatesmalleronesareavailable

FACEPLATEWORK

Another basic way of holding work is on the faceplate Thismethod is used when the component is too large or isawkwardly shaped andwould be difficult to hold in a three-orfour-jaw chuck Usually the work is clamped directly onto thefaceplate often with a packing piece behind it to protect thefaceplateThefaceplateshouldbeflatandtruesothefirstthingtodo

whenyougetthelatheistocheckthefaceplatewithadialtestindicatorCarefullycleanthemandrelnoseandtheinternalholeinthefaceplateMakesurethemandrelcanturnfreelybyhandwith the lathe switched off and check that the face of thefaceplateisrunningtrueasclosetotheouteredgeasyoucanget If it is runningtrue runthetest indicatoracross the frontfaceofthefaceplatethisshouldbetrueaswellIfthefaceplateis running out itwill need to bemachined Put the lathe intobackgear if ithas it (topbackgearwillprobablybe fine)Youwill need a carbide-tipped tool ideallywith a small 45-degreechamferonthetipBringthetooluptothefaceplateand lockthe carriage Next you need to lightly face the faceplate right

acrossitsdiameterIfyouhaveapowercrossfeeditwillmakelight work of this but if not you can feed across by handFortunatelymost faceplateshavea series of rings on them toaid in setting up the work Machine the faceplate from theoutsidetothefirstringandstopforarest feedtothesecondring and so on until finished Depending upon how badly outyourfaceplateisyoumayhavetodothismorethanonceuntilit iscleanedupbutwhen it isdoneyouwill rarelyneedtodothisexerciseagain

Machiningaholeinablock

Asmentionedpreviously the ringsmachined on the faceplateareguidestohelpyousetuptheworkThiswilldoiftheworkisaroundcomponentbutweneedadifferentmethodiftheworkis square Take a block of metal for example that has beenmachinedalloverWewanttomachineaholeinit2infromoneedgeand1in fromanother edgeMarkout thepositionof theholeandcentrepunch it Put adeadcentre into the tailstockholdtheblockontothefaceplatebringthetailstockuptowardsthechuckandlockitWindthetailstockbarrelandcentreuptothe component and engage with the centre pop Lock thetailstock barrel Clamp the block to the faceplate using somepackingpiecesandfourclampsontheblockTheholeisnowoncentreandwecanmachineitinthecorrectplaceIf we need more than one hole placed accurately in the

componentwecanusetoolmakerrsquosbuttonstoensuretheholesare in the correct place Toolmakerrsquos buttons usually come insetsof fourOnebutton isusually longer than the rest soyoucanstillclockthediameterwhenitisclosetoanotherholeSetsare often available second-hand on eBaywhile they probablyhaveanobscureAmerican threadyoucanclamp themto theblock using your own BA or metric screws together with awasher

Settingupthefaceplateusingthetailstock

Asetoftoolmakerrsquosbuttons

Tofitthemtothecomponenttobeboredmarkoutdrillandtap holes in the approximate positions where the holes areneeded If you need a pair of parallel holes place thecomponentonasurfaceplate looselyfitthebuttonsandpushthem down onto a parallel or similar block of the correctthicknessandnipthescrewsupThespacershouldbesmallerthanrequiredbyhalfthediameterofabuttonIftheholesneedtobeacertaindistanceapartuseaspacer

of the correct size between the buttons (Remember tomake

thespacersmallerbyonediameterofthebutton)

Settingupacomponentusingtoolmakerrsquosbuttonstogetafixeddistancefromtheedgeofacomponent

TherearelotsofdifferentwaystosetthespacingofbuttonsItismainlyamatterofcommonsenseCastingsandflatcomponentscanbeboltedtothefaceplate

for machining A typical example of a flat component is aneccentric strap This type of component is usually made of acomponentthatiscutinhalfandboltedbacktogetherAholeisthenboredinitonthecentrelinetofittheeccentricThistypeofcomponentisoftendifficulttoholdinthelathechuckandisprone to distortion Castings are often too large to fit into alathechuckandso the faceplate iscalledon toundertake theworkAcastingcanoftenbebolteddirectlytothefaceplatetofacilitateeasymachining

Settingupacomponentusingtoolmakerrsquosbuttonstogetafixeddistancebetweenthecentresofacomponent

Work on the faceplate is often an odd shape or is set off

centreThiscauses it tobeunbalancedandasaconsequencethe lathemayvibratewhile thework is turningTocounteractthis tendency the faceplate should be counterbalanced byboltingweightsontoitAusefulsourceofweightsisthelathersquoschange wheels By bolting a change wheel or two onto thelightersideofthefaceplateyoucanbringthewholeassemblybackintobalanceAfterboltingthechangewheelsonspinthelathe by hand to check the balance The faceplate should notshowatendencytostopatoneparticularpointWhenyouarehappy that the faceplate is in balance the work and balanceweightsareboltedontightlyandsothattheworkdoesnotfoulthe lathewhen turnedbyhand switch themachine on in lowback gear to check for vibration Depending on what you areturning you should be able to run in top back gear or evenbottomdirectspeed

Asimpleclampsetisveryusefulwhenmachiningacastingonthefaceplate

TurningaFlywheel

Oneofthemainusesofafaceplateisturningalargediameteriron casting typically a flywheel or a locomotive wheel for asteamengineTheflywheelshouldbemountedsothattheinneredgeoftherimandtheouteredgeofthehubruntrueIfeitherofthemrunsoutitwouldbebetterthatthehubrunsoutasthe

rimwillbemorenoticeableonthefinishedengineClamp the flywheel down with some packing under the

spokessothatyoucanturnrightacrosstherimBecarefulthatyouclamptheflywheeltightenoughsothat itdoesnotmovebutnotsotightthatitdistortsRoughturn theoutsidediameterand facetherimusingthe

backgearUsingadirectdrivespeeddrillandborethecentrehole and either finish off with the boring tool or use a reamDonrsquot try reamingwithout boring the chances are that if youdotheholewillnotbetruewiththerimasthedrillprobablydidnotcutanaccurateholeDropdowntothetopbackgearspeedface the rim and turn the outside of the rim to the finisheddiameter Turn the flywheel over and finish the other face towidth

Astubarborsuitableforcentralizingalocomotivewheelorflywheel

TurningLocomotiveWheelFlanges

LocomotivewheelflangescanbeturnedonafaceplateYoucanpurchase blank end Morse taper arbors that fit into theheadstocktaperFitoneoftheseandturnaspigotonittotake

thewheel bore Thewheel bores should all be the same sizebut if they are different sizes machine the spigot to fit thelargestboremachinetheflangeonthatonethenmachinethespigotdowntofitthenextonemachinetheflangeandsoonIdeally the wheel bores should all be the same size but if

theyarenotproceedas followsSkimtheoutsidediameterofthe wheel flangemeasure and take it to the correct finishedsizeMovethelathetoolinbythedepthoftheflangeandturnthe tread Deal with all wheels like this machining all of theflangeoutsidediameterstothesamesizemovinginthecrossslidebythesameamounteachtimesothatallthetreadsendupthesamesize

UsingtheKeatsVeeangleplatetoturnaneccentriccomponent

KeatsVeeAnglePlate

TheKeatsVeeangleplate ismountedon the faceplateand isusedtoholdroundbarsquarebarandmiscellaneouscastingssuch as cylinders and steam chests The angle plate can bemountedanywhereonthefaceplateaslongasthelathecanbe

rotated safely and is in balance When spun by hand thefaceplateshouldnotshowatendencytostopatanyparticularplacewhenrununderpowerthelatheshouldnotvibrateAswellasholdingbarandcastingsforturningtheKeatsVee

angleplateisveryusefulformakingeccentriccomponentssuchastheeccentricsforasteamengineTo turn an eccentric use a test indicator to check that the

roundbarisrunningreasonablytrueWhenthisissatisfactoryyoucanturntheoutsidediameterofthebartofittheeccentricstrap (or component) including any step or groove requiredNextoffsettheKeatsVeeangleplatebytheamountyouwantthe eccentric lsquothrowrsquo to be Use the dial test indicator tomeasure the offset of the outside of the eccentric The offsetshouldbetwicethethrowYoucannowdrillboreandreamtheholeintheeccentricYounowhaveenoughbasic knowledge to carryout turning

between centres andwork accurately on the faceplate In thenext chapterwewill lookat holdingwork in a collet andonamandrel

7ColletsandMandrels

Thischapterexplainsallaboutholdingworkinacolletandhowyou canmake and use several different types of mandrel forworkholding

ERcollets

USINGCOLLETS

Quite a few different collet systems are to be found inworkshops Some are used for holding tools such as millingcutterssomeareusedforbarorworkpieceswhilesomemaybeusedwithbothbarandworkpiecesOne of the commonest is the ER collet which comes in

severaldifferent sizeseachhavingadifferent largediameterTheERcolletsystemallowsupto0039in(1mm)collapseofa

colletalthough in thesmaller sizesyoucanbuy thecollets in05mmincrementsA16mmcolletforexamplewillholdroundmaterialdownto15mmdiameterWhatevertheERcolletsizetheyallappear togodownto1mmminimumwhichwillclosedownto05mm

ERcolletadaptor

TherearemanytypesandsizesofERholderavailableAlltheusualMorse taper shank sizes are available and you can alsobuyvariousdiametersofextendedparallel shankholdersTheproblemwiththeseisthattheyaregreatforholdingtoolsthathave a short shank but because you need to use the holderwithadrawbaryoucanrsquotputlongbarstockrightthroughthemTo overcome this for lathe work you can also buy ER colletholdersdesignedtobefittedtoachuckbackplatethatyoucanmachine to suit your lathe so ensuring good concentricityBecause they donrsquot use a drawbar you can fit bar stock rightthroughandintotheheadstockmandrel

ERcolletadaptorfittedtoabackplateIalwaysleavebackplatesoversizesoIhavesomethingwithwhichtoclampthemdownwhenusedonamillordrill

When buying new and second-hand ER collets make surethey have the retaining groove near the nose end The older(andobsolete)EandEScollet typesdonothavetheretaininggrooveandarenotinter-changeableYouaremostlikelytofindEandEScolletsincludedwithasecond-handUnimatlatheDraw-in collets are usedwith a drawbar or collet tube The

drawbardrawsthecolletuptightbydrawingit intothelathersquosmandrelbyabar that runs through thecentreof themandreland screws into the centre of the collet Thismeans that youcannotputbarstockrightthroughthecolletToovercomethissome Morse taper collets use a hollow draw tube the collethaving an external thread tomatch the internal thread of thedrawtube

Draw-incollet

Special collets are made for the Myford ML7 Super 7 andML10 lathes These are Morse taper collets but rather thanhavingadrawbartheyareclosedwithanoseringthatfitsoveragrooveinthecolletThenoseringtightensthecolletintotheheadstockmandrelrsquos Morse taper It is extracted after use byundoing the nose piece which draws the collet out from theMorsetaperbythenosegrooveImperialandmetriccolletsareavailableuptofrac12in(12mm)diameterDead lengthcolletsareavailable that fit intoanattachment

usually fixed to the front of the lathersquosmandrel These colletsarecalleddeadlengthbecausetheydonotmovelongitudinallyunlike draw-in collets You are more likely to find collets likethesesecond-handratherthannew

BoxedsetofMyfordcollets

Deadlengthcollet

AvariationofthedeadlengthcolletistheCrawfordMultiborecolletThissystemhascolletsmadeofsegmentsheldtogetherbyspringsThecolletsareofvariablediameterandhavequitea

largeclosurerangeTheyaremorelikelytobefoundonalargercommercial lathe although you can get collets for smallermachinesWatchmakerrsquoscolletscanbeused inmost lathesbymaking

an adaptor for the headstock and a drawbar (or tube)Watchmakerrsquos collets are very accurate and can go down toverysmallsizesbuttheyhavelimiteduseinmostworkshopsYou can get a special watchmakerrsquos spindle for the EmcoUnimatlatheandthereisalsoaversionoftheCowellslathetheCW90thattakeswatchmakerrsquoscolletsFormost of thework carried out on the lathe youwill find

thatanERholder thatmountsontoachuckbackplate ismostuseful

Simpleexpandingmandrel

Simpleplainmandrel

MAKINGMANDRELS

There are several types of mandrel in common use inworkshops The most common is probably the expandingmandrelwhichcaneasilybemadeinanyworkshopInitsmostbasic form it is a bar turned to a size to fit the bore in theworkpieceItisthenthreadedwithataperedtapandslitat90degrees togive foursegmentswhichare thenexpandedbyascrewfittedintotheendofthemandrelAnother common mandrel is the tapered mandrel This is

usuallyalsquobetweencentresrsquomandrelandisoftenmadetotaperfromjustacoupleofthouovernominalsizetoacoupleofthouunder nominal size It is usually hardened and has a groundfinishTheworkpieceisheldinplacebybeingpushedontothemandreluntilitistightToremoveitjustpressitbackoutthewayitwentinWhereconcentricityisnotquitesoimportanttheworkpiece

canbeputonaplain turnedmandrelandtightenedupwithaboltandflatwasherExpandingmandrelsarealsomadecommerciallybutasyou

need a mandrel for each individual size of hole it can getexpensive if you need more than one or two different sizesCommercialmandrelscanbeobtainedwithMorsetapershanksto plug straight into the headstock Thismethod ensures thatthe mandrel should run dead true assuming both the Morsetapermandrel and theMorse taper in the headstock are bothcleanandfreefrommarksorswarfYou can also purchase Morse taper arbors with blank end

pieces from which to make your own mandrels First we willmake an expandingmandrel from a blank Morse taper arborYouwillneedtoturnthearbordowntofittheworkpieceboreIusually turn themandrelabout0010in (0025mm)oversize tostartwithandthenIdrillandtapthearborwithataperedtapThe drilled hole can go quite deep but the tapped hole onlyneedstogoinuntilthelockingbolt isabouthalfwaydownthelengthwheretheworkpiecewillsitPut the mandrel into the vice and cut along the mandrel

making four cuts around the circumferenceRetap thehole to

cleartheswarf fromthethreadandputthemandrelback intothe headstock taper Now you can lightly nip the screw up toexpandthemandrelslightlySkimthemandrel to finishedsizeuntil the workpiece will fit on without shake You can nowfurther tighten the screw so that the workpiece tightens ontothe mandrel When you slacken the screw the workpiece willcome off easily as you have skimmed it while it was slightlyexpandedYoucanmakeanexpandingmandrelfromabarheldin the three-or four-jawchuckorperhapsacollet inasimilarway Ifheld inachuck itmaynotgoback true ifyouneed touseitagainsoifpossibleyoushouldholdthearborinacolletFor aplainmandrel turn thediameter to fit theworkpiece

anddrillandtapforacapscreworaboltThereisnoneedtosplit this type ofmandrel You simply put the workpiece ontothemandrelandholditonwithaflatwasherAgainitdoesnotmatterwhetheryouuseabarinachuckorcolletorifyouusea Morse Taper blank arbor Arbors are very useful in theworkshop If youmake them fromMorse taper blanks or holdtheminacollettheycanbeusedoverandoveragain

8TaperTurningandLatheAccessories

Thischapterexplainshowyoucanturnataperusingatopslidetheuseoffixedandtravellingsteadiesandformtools

Turningataperwiththetopslide

TAPERTURNING

SometimesyouwillhavetoturnataperintheworkshopThatisa fairly easy jobWhat ismore difficult however is having toturnmatchingmaleandfemaletapers

Themethodyouaremostlikelytouseintheworkshopistoturn the two tapers with the top slide You should be able toturna taper longenough foraMorsetaperusingthismethodThemostimportantthingwhenturningtapersistoensurethatthe tool tip is at the exact centre height of the lathe This isbecause the taper will vary if the tool is not dead-on centreheightProbably the easiestmethod of turning aMorse taper is to

useadial test indicator toclocka lathecentreof therequiredMorse taper between centres The smaller end of the tapershouldbeatthetailstockendofthelatheThetopslideshouldbewoundalongthetaperby itshandwheelwhilethecarriageremainslockedThetopslideshouldbeadjustedangularlyuntilthedialtestindicatorreadszeroallthewayalongNowyoucanfinish turn the external Morse taper using an internal MorsetapersleeveasagaugetocheckthattheangleiscorrectTodothis make marks with a felt tipped pen along the taper andcheck that the test sleeve rubs evenly all the way along themaletaperAdjustifnecessaryuntilyouhaveaperfectfitToturnthematchingfemaletaperthelargeendofthetaper

willbeat the tailstockendand theboringbarwillbe invertedandcuttingon thebackof theholeDoing thismeans thataslongasbothofthetoolsareatcentreheightthetapersshouldmatchWecanusethemaletaperthathasjustbeenturnedasatestbarBoreoutthetaperverycarefullyyouwonrsquotneedtoremovemuchmaterial before the test taper goes too far intothe finishedbore Testwitha felt tippedpenuntil youhaveaperfectfitYou can turn any taper you need this way you are not

restrictedtoMorsetapersAnothermethodmostoftenusedforlongshallowtapersistouseataperturningattachmentTheseattachments are often available as extras on higher qualitylathes They comprise a slide mounted onto the back of thelathe Often the guide is dovetailed with a sliding blockattached to the cross slide to guide the tool on a taper ThedepthofcutisusuallyputonusingthetopslidesincethecrossslideisusuallydisconnectedfromthefeedscrewInthiswayit

isfreetomoveinandoutcontrolledbytheguide

Taperturningattachment

Settingthetopslidebyclockinganexistingtaper

Anothermethodweshalllookatfortaperturningistooffsetthe tailstock on its base This will make the work turnedbetween centres become tapered either large or small at thetailstockenddependingonwhichwaythe tailstock isoffset ifsettowardsthebackofthelathethediameterwillbelargerat

the tailstock end if the tailstock is moved to the front thetailstockendwill be smaller indiameter Theamountof taperthatcanbeturnedinthismannerislimitedsincetheheadstockandtailstockcentresareoutoflineThe final method of offsetting the workpiece is by using a

boringhead inthetailstockYouneedahome-madehardenedsolidcentrethatfitswheretheboringtoolwouldnormallygo(AsmallUnimatlathesizerunningcentremightbeideal)SettheboringheadsothetooltravelishorizontalYoucanthenoffsettheboringheadcentresocreatingataperThisisthesameassetting the tailstock over but you donrsquot have to realign thetailstockafterwards

Usingthefixedsteady

USINGFIXEDANDTRAVELLINGSTEADIES

The fixedsteady isusedmainly to turn theendofabaror tocentre a workpiece that is too large to fit through the chuckObviously bar stock should not protrude from the chuckmorethan is necessary to work on This is where the fixed steadycomesinThefixedsteadycanbesettothediameterofthebarsothattheendofthebarcanbemachinedsafely

Thesteadycanbesetusingachuckmountedonthistailstockadaptor

Travellingsteady

Settingthesteadybyusingachuckmountedonanadaptor

Onewaytosetthefixedsteadytosizeistoturnabitofbarin the chuck to the same size as the barwewant to use thesteadyonThenwecanmovethefixedsteadyalongthelathebedandfittheworkpieceintothechuckandinthesteadyTheendof thebar nearest to the tailstock shouldnowbe runningtrueandcanbeworkedonsafelyThebarcanbecentredrilledfacedorotherwiseworkedonAn alternative way to set the steady is to support the

tailstockendof thebarwitha threejawchuckmounted in thetailstockAdaptors to take the threejawchuckareavailableoryoucouldmakeyourownJustsupportthebaratbothendsinthethreejawchucksandsetthesteadyfingerstothebarThe fixed steadycanalsobeused to support tubes thatdo

nothaveanymaterialinthecentreThe fingers of the steady need to be lubricated regularly

while inuseThis iseasilydonebydrillinga smallhole in thetopfingerwithacountersinkinsidetheslottotakeoilThetravellingsteady ismostoftenusedwhenturningdown

small diameterbarsor screwcutting long slenderbars It boltsonto the front of the cross slide in line with the chuck and

travelsalongwhenthecrossslideismovedalongthelathebedWhen turning the travelling steady can either be set to thediameterofthebarbeforeturningandtoleadthetooloritcanbesettothefinisheddiameterrequiredandtofollowthetoolNormallythefingersaresetto leadtheturningtoolbut if thebarisroughforexampleifitisdentedorrustyitisbetterforthefingerstotrailtheturningtoolIfscrewcuttingthetravellingsteadyshould lead the toolso that itdoesnotdeflectorwearduetoaburrbeingthrownupbythescrewcuttingtoolSteadies will not be used very often but they are

indispensableontheoccasionswhentheyareneeded

Travellingsteadywithleadingfingers

Travellingsteadywithtrailingfingers

MAKINGASIMPLEFORMTOOL

Youmay often need to produce a particular shape such as aradiusonacomponentTheeasiestmethodtodothisiswithaformtoolAsanexamplewewillmakeasimpleformtooltocutahalfcircleonabarofbrassForaradiusof3mmforexampleweneedtoproducea formtoolusinga6mmdiameterdrillorreamFormaterialwewillusegaugeplateahighcarbonsteelthatcomesintheformofagroundflatbarApieceabout5mmthick and10mmwide is needed although the size is not thatimportantaslongasthegaugeplateisthickenoughtoabsorbanyturningstressesIdeallyweneedataperedreamerthatwillproduce a 6mm diameter hole somewhere along its lengthalthough you could use a parallel 6mm reamer a slot drill orendmillorevenastandardtwistdrillDrill a hole through the gauge plate and open up to 6mm

diameterAim togetagoodsurface finishon thesidesof thehole Hacksaw and file half the hole away to leave the shaperequired on the finish turned component Now we need to

harden the tool although ifweare justdoingacomponentortwoinbrasswecouldprobablygetawaywithouthardeningitHardeningissimpleenoughheattheworkingendofthetool

toredstopheatingandletthegaugeplaterestforacoupleofminutesThiswillgive thegaugeplateachance tochange itsinternalstructureReheattoredandquenchinatubofwaterThisshouldhardenthetoolAlthoughabitbrittle itshouldbefine for making a few components Stone the top of the tooluntil thecuttingedge issharp Ifnecessaryyoucanpolishtheinside of the radius that is going to do the cutting There areseveralmethodsyoucanuse includingapieceofwetanddrypaperaroundabitofbaraverysmallgrindingwheelcalledamounted point or a bit of round bar with fine valve grindingcompoundonitWhicheveryouuseaimforapolishedfinishasthe finish on the turned component is directly related to thefinish on the form tool You canmakeall sorts of simple formtools with gauge plate a typical example being a facing toolwitha30-degreechamfertofaceandchamfernuts

CopytemplatereadytouseMetal

MachiningfromaTemplate

MachiningfromaTemplate

YoucanmachineaprofilefromasimpletemplateThetemplatecanbecutfromgaugeplatewithafileormachinedbutitdoesnot need to be hardened The template could be used tomachinea large radius suchasa smokeboxdoor Inuse thetemplateismountedonablockonthelathebedandthecrossslide is kept in contact with the template by being pushedagainstthetemplatewithaballracefixedtothecrossslideInthenextchapterwewillbelookingatdrillingandreaming

9DrillingandReaming

ThischapterexplainshowtousedrillsandreamersinthelatheTherearemanydifferenttypesofdrillsandreamersTheyareessentialtomakingcomponentsinthelatheWewilllookatthevarioustypesandhowtochoosethespeedsandfeedsforusingthem

Thisdrillchuckrequiresachuckkey

TYPESOFDRILL

Drills are normally held either in the tailstock if they have aMorsetaperor inadrillchuckiftheyhaveaparallelshankA

drillchuckismountedonaMorsetapershankthatisusuallythelargestMorsetaperthatthetailstockwilltakeThelargestsizeof drill that will normally fit a drill chuck is frac12in (13mm) indiameter although larger chucks are available at a cost Thesmallest sizeofdrill thatafrac12in (13mm)drill chuckwill take isusually about 116in (15mm) This is because the larger drillchuck is incapableofclosingdownenoughto take thesmallersizesofdrillThismeanswewillprobablyneedtwodrillchucksoneforlargerdrillsandoneforsmallerdrills

Hand-tighteningdrillchuck

TherearetwomaintypesofdrillchuckOneistightenedbyusinga chuckkeywhichhasa small bevelgearbuilt on to itthatmates with the outer sleeve of the drill chuck itself Theother type is hand tightenedwhere the outer chuck sleeve isknurledtotightenthedrillthesleeveisturnedbyhandLargerdrillsabovefrac12in(13mm)usuallyhaveaNo1orNo2

MorsetapershankYoucangetMorsetapersleevestoconvertalargeMorsetoasmallerMorsetaperYoucanalsogetasmallMorsetolargeMorsetaperconverteraswell

Drillwithataperedshank

Some larger drills are also available with parallel shanksTheyaremadewithasteppeddownfrac12inparallelshankandarecalledblacksmithrsquosdrills

Blacksmithrsquosdrill

Themostusefuldrills in theworkshopcomeassetsofhighspeedsteeljobberdrillsinacaseThemostpopularsetcovers1mmto6mm increasingby01mmstepsAnotheruseful setcoversfrom6mmto10mmalsoincreasingby01mmstepsIfyouareintomodelengineeringasetofnumberdrillsfromNo1toNo60istoberecommended

Asetofmetricdrillscovering1ndash6mm

Drills are also available in different lengths Stub drills areshorter than standard jobber drills Several lengths of longseries drills are also available ranging from one and a halftimesthelengthofajobberdrilluptoseveraltimesthelength

Differentlengthsofdrills

Mostdrillshavetwoflutesbutcoredrillsarealsotobehadwith three four or evenmore flutes As their name suggeststhese are usually used for drilling out cored holes in castings

CoredrillsarenotnormallycapableofstartinganewholebutareusedforopeningupexistingholesAstandarddrillusuallyhasanincludedangleof118degrees

Stub drills and cobalt drills often have a 135 to 140 degreeangle for use on hardermaterials such as stainless steel andaircraftsteelsBack rakeondrills is oftenground radially Another typeof

pointhoweverhasfourfacetstothepointFour-facetdrillsaremuch better at starting a hole than a standard jobber drillwhich tends towanderunless followingacentrepoporcentredrill Four-facet drills also require less pressure to drill a holesincethepointisthinnerthanastandarddrillandtheyarefareasier to sharpen accurately by hand than standard jobberdrillsDormerdoarangeoffour-facetdrillscalledA002withatitaniumnitridecoating(TiN)andafour-facetpoint

Three-flutecoredrill

DormerA002four-facetdrillpoint

To drill an accurate sized hole requires two ormore stepsfirst youdrill the hole undersize (by perhapsfrac12mm) then youfollowthroughwithasizedrillThechancesaretheseconddrillwillcutdeadtosizeasitisonlycuttingasmallamountfromthediameter Obviously if you are drilling a large hole moreintermediatestepsmayberequiredSpeedsfordrillingarethesameasthosegivenforturninginthetableinChapter3

Setofcentredrills

REAMERS

There are several types of reamers available for use inworkshops again with either Morse taper or parallel shanksSomehavesizeparallelshankstheshankbeingthesamesizeas the reamer while others are availablewith shanks smallerthanthereamedsizeThereisalsothewaistedreamerwheretheshankisthesamesizeasthereamerthemiddleissmaller(waisted)andthecuttingendistheholesizeYoucanalsogetadjustablereamerswheretheendisexpandedbytheuseofascrewinthecuttingendofthereamer

Handreamerthefrontparthasaslighttaper

Straightshankmachinereamer

Waistedshankmachinereamer

Morsetapershankmachinereamer

Parallelreamersaredividedintotwotypesparallelmachinereamerswhere thecuttingdiameter is thesameallalong theream and hand reamers where the cutting end is slightlysmallerandtapersuptothefulldiameterWhen drilling a hole for reaming it is advisable to use the

two-holemethodfordrillingYouaremore likelytogetagoodsize hole prior to reaming For small reamers up to 04in(10mm) leave about 0012in (03mm) for the reamer toremoveForreamersuptofrac34in(19mm)leave0016in(04mm)and over frac12in (13mm) leave 0020in (05mm) For reamingspeedsuseabouta third toahalfof thedrillingspeed for thesamediameterFeedsshouldbefrom0002to0004in(0025ndash005mm)per toothper revMultiply the feedper toothby thenumberofteethtogivethefeedperrevolutionItisbesttouseneatcuttingoilformostmaterialsexceptfor

aluminiumforwhichparaffinshouldbeusedandplasticwhichrequirescompressedairorplainwaterYoushouldnotuseoilasacuttinglubricantforanytypeofplasticasitcanattackandordegradetheplastic

10BoringToolsandBoringHeads

Thischaptershowsyouhowtoboreholesinthelathewiththeworkheldinachuckmountedonthefaceplateorfixedtothelathecrossslide

TypicalHSSboringbar

DIFFERENTTYPESOFBORINGBARS

BoringaholetosizeisoneofthemostexactingjobsyoucandoinalatheItisrelativelyeasytoturnashafttofitaholebutitis much harder to bore an accurate hole to fit a shaft Ifpossibleyoushouldboretheholebeforeturningtheshaft

YouarelikelytocomeacrossHSSboringbarsorinsertedtipboringbarsBothhavetheirusesTheHSStoolisidealformostgeneralhole-boringjobsbuttheinsertedtiptoolisfarsuperiorfor materials such as cast iron The boring bar should be aslargeasyoucangetintotheholewhilestillallowingswarftoberemovedTheboringbarshouldonlyprotrudefarenoughtoenableitto

go completely through the bore Any more protrusion than isnecessarymay result in chatter or a dig in in the bore Thefront clearance on the boring bar tip should be as small aspossiblewithoutrubbingasstrengthisimportantBoringcanbeusedtofinishaholetosizeorsimplytotruea

holeupafterdrillingandpriortoreaming It isbesttoruntheboringtoolthroughtheholeusingafinefeedtothecarriageifyouhave the feedoptiononyour latheThe final finishingcutshouldbeputthroughtwoorthreetimesatthesamesettingtoeliminateanyspringinthetoolworkorlatheIftheholehasanintermittentcutthroughitsuchasacrossholetheholeisbestboredtosizeIt ispossible toborequite smallholes if youhave the right

tool Commercial lsquosmall holersquo boring tools are very expensivebut Ibuythemsecond-handwhenever Iseethemso Iusuallyhave a stock It is easy if time consuming to grind up smallboringbarsbuttheyareveryusefulespeciallywhenyouneedtotrueupasmallholepriortotappingorreamingEndmillsandslotdrillsmakeusefulboringtoolsAs longas

yougetthecuttingedgeoncentreheighttheywillboreaswellasaproperboringbarespeciallyinaluminiumYoucanmakesimplehome-madeboringtoolsbydrillingand

reamingaholetotakeaHSStoolbitintoasteelshankIdeallythe shank should be made of high tensile material or silversteelThetoolbitshouldbesecuredwithahightensilesocket-headedgrub screwor similar The tool bit caneitherprotrudefromthesideoftheboringbarforthroughholesorprotrudeatthe frontof theshankat45degrees ifyouareboringablindholeRoundboringbarscaneitherbeclampedintotheVeegroove

foundinsometoolholdersorheldinasplitsquareshankEithermethodissuitableespeciallyastheshankcanbeslidinoroutofthetoolholdertominimizeprotrusionSpeciallyshapedtoolbitscanbeusedtoundercuttheendof

the borewhen it needs to be screwcut and canrsquot be cut rightthrough Inserted HSS boring bars can also be ground up forundercuttingbeforescrewcuttingThereareseveralmethodsofcheckingaboreforaccuracyIf

youhavetoboretheholetofitanexistingcomponentperhapsaballraceyoucanuse theexistingcomponentasagaugeorturnupagaugeRoughout theborewithina few thouof thefinishedsize taking twoor threespringcutsUsea telescopicgaugeapairofcalliperswithamicrometeroradigitalverniertomeasuretheholeBorethestartoftheholebynomorethanonethouata timedonotgoright throughtheboreTest thefrontoftheboreifthegaugedoesnotgointotheborerunthetool right throughunderpower feedBoreout the frontof theholebyanotherthouchecktheboreandrepeatuntilthegaugejustgoesintothestartoftheholeFinishtheboreatthesamesetting checking that the gauge just enters Take a couple ofspringcutstoensuretheboreisparallelYoushouldnowhaveanaccuratelysizedholeThe trick to boring is to finish with very fine cuts Many

engineersdonotrecommendfinecutsbutIhaveneverhadaproblemaslongasthetoolissharp

Asetoftelescopicgaugesforcheckingaboreusedinconjunctionwithamicrometer

Checkingaborewithahome-madegaugeTheleadinisonethousmallerthantheborerequired

USINGABORINGHEADINTHELATHE

AnothermethodofboringacomponentinthelatheistoboltitdowntothecrossslideWhentheworkpieceisbolteddownandtheholeposition is linedupwith theheadstock youcanboretheholeintheworkpieceinseveralwaysFirst however you might need to put a hole into the

workpiece to clear the centre of the hole out of theway Youcandothisbyusingadrillinathree-orfour-jawchuck(smallerdrillscouldbeusedinadrillchuck)Startwithasmalldrillandworkupalmosttothefinishedsizeoftheholetobebored

Boringaholereadyforreaming

Toboretheholethefirstoptionistoholdaboringbarinthethree-jaw chuck This is a good basic method of boring aworkpieceonthecrossslideTheonlyawkwardbitisadjustingtheboringbarsothatasizeholeisboredThisisusuallydonebyanadjustingscrewpressingontothebackofthetipoppositethe cutting edge The tip itself is usually clamped by a grubscrewthroughthesideoftheboringbarHoweveryoucanuseaboringbarthatisafewthouundertherequiredsizeandfinishoffwithareamerA similar way that is easier to adjust is to use the same

boringbar in the independent four-jawchuckThen insteadofadjusting the tip in the boring bar you can adjust the entireboringbar inthefour-jawchuckThisasyoucanimaginewillbealoteasierthantryingtoadjustthetipintheboringbarThethirdmethodofboringworkonthecrossslideistousea

properboringheadThis iseasy toadjustas it isdesigned forthisverypurposeFinallyyoucouldusea lsquobetweencentresrsquoboringbarwhich

isheldbetweentheheadstockandtailstockcentresThisistheonly option when you are doing a long bore such as a largecylindercastingforalocomotiveortractionengine

Boringtheholeusingthefour-jawchuckmethod

Usingtheboringheadinthelathemandrel

Unlike when you are facing and boring a component in achuck you will not be able to face across the front of thecomponent (Boring heads with the ability to face across theworkareavailablebutareunlikelytobefoundintheamateurrsquosworkshop) Thismeans you will have to face across the workwith a flycutter in order to keep the face true with the boreFlycutters are available quite cheaply or you couldmake yourownandholditinthefour-jawchuck

Aflycuttersuitableforfacingthefrontofacomponentthathaspreviouslybeenboredonthe

crossslide

11KnurlingRadiusTurningandProductionMethods

This chapter explains how to use knurling tools and radiusturningtoolsaswellasusingbasicproductionmethods

KNURLING

Knurlingistheprocessofformingorimpressingapatternonapiece of metal often for the purpose of making a grip for apieceofequipmentsuchasaknobBothstraightanddiamondknurlscanbeproduceddependingonthetypeofknurlyouareusing Diamond knurling is usually done with two knurlingwheelsalthoughsingle-wheeldiamondknurlsareavailableKnurls are also available in fine medium and coarse sizes

although the size is relative fromdifferentmakers The speedfor knurling is usually about half of the turning speed for thesame diameter bar Normal knurling is of the male patternwheretheknurlingconsistsofraisedpyramidsFemaleknurlingismuchrarerandconsistsofdepressedpyramidsThere are threemain types of knurling tool but only two of

these are found in the average workshop The first type ofknurling tool is the so-called lsquocutrsquo knurling toolwhichactuallycutsaknurlratherthanpressestheknurlintotheworkThisisaspecialized tool more often used in industry and is veryexpensivesoitisnotfoundinmanyhomeworkshops

lsquoBumprsquoKnurling

The most common knurl is the single-or double-wheel knurlsometimes called a lsquobumprsquo knurling tool The wheels aremountedat the frontof the tool This typeof knurl is pressedintotheworkbyusingthecrossslideandcanproduceagoodqualityknurlHowever itdoesputveryheavypressureonthemandrelandlathebearings

Acommerciallyavailablestraddleknurlingtool

StraddleKnurling

Thebest typeofknurl foroccasionaluse is thestraddleknurlwhich has two knurling wheels that completely straddle theworkpieceThistypeofknurldoesnotputastrainonthelathebearings and so is preferred bymost lathe users (Two-wheelknurlingtoolsareavailablethatresemblestraddleknurlingtoolsbut they donrsquot open up to take anything more than smalldiameters relying on pressure at the side of the job like alsquobumprsquoknurl)To set the straddle knurl up wind the tool against a bit of

plateheldontothesideofthebarRemovetheplateandmovethetoolinbythethicknessoftheplatehalftheknurldiameterandhalfthebardiameterThiswillputthetoolontothecentrelineofthebar

Settingtheknurlingtool

In use set the knurling wheels to the centre as describedabove wind the knurls onto the outside diameter of the barwindtheknurlawayfromthebarandmovetheknurlingwheelsclosertogetherbytwicethedepthoftheknurlpatternSwitchthelatheonandwindthetoolbackontothecentrelineandthetool should start to form the knurl You can now traverse theknurlingtoolalongtheworkpieceto formtheknurl remembertousecuttingoilNote that theknurlsshouldhavechamferedsidesifyouaretraversingalongtheworkpieceYouneedtogodeepenoughsotheknurlisfullyformedbut

notsodeepastodeformtheknurlBecausetheknurlstraddlestheworktheknurlsstartoff independentlyandmaynotbe inalignment around the diameter Once you start moving theknurlingtoolbackwardsandforwardsalongtheworkhoweverthetoolshouldlineitselfupThismeansyoumayhavetoturndownorpartoffthebarwhereyoustartedtheknurlIfyougotoodeepespeciallyinaluminiumthewholedepth

ofknurlcouldgetdestroyedandevendropoff theparentbarThis is called flakingKnurling isnotadifficultprocessa littlepracticewillsoonhaveyouknurlinglikeaprofessionalengineer

Anaccomplishedbitofknurling

AformtoolcuttingaballTheinsetviewshowstheformtoolandafinishedball

RADIUSTURNING

Sometimesweneedtoformanexternalradiusontheendofabit of bar perhaps for a ball-shaped handle We can use asimple lathe attachment to do this Basically the attachment

consists of a short turning tool mounted onto a U-shapedcomponent that is arranged to pivot on another U-shapedcomponentheldinthelathetoolpostBy pivoting the attachment back and forth a radiuswill be

generatedForatrueradiusthepivotpointshouldbesetonthecentrelineofthebarTheradiusgeneratedwilldependonhowfarthetoolbitissetbackfromthecentrelineoftheworkpieceTosetthetoolupwindtheattachmentuptoaplateheldto

the sideof thebar youareworkingon remove theplate andwindinthewidthoftheplatehalfthewidthofthebarandthewidthofthefixturetothecentrelineofthepinThiswillputthepivotonthecentrelineThenyoucansetthetooltotheoutsidediameterofthebarThiswillproduceaballthesamediameterasthebarTo turnan internaldiameteruse the samemethodbut the

turning tool will need to pass through the centre of the pivotand out the other side You will be limited to shallowdepressionsratherthanlargesemicirclesbutthistechniquecanstillbeusefulonoccasionThealternativemethodof formingaball iswithaball form

tool

Astopbarblockforthecarriagestop

PRODUCTIONMETHODS

PRODUCTIONMETHODS

Foreaseofproductionthefirstthingyouneedtouseisabedstop (see Chapter 5) The chances are that you will need tomakeyourownTheoneIuseisveryversatileandconsistsofablockmountedatthefrontofthelatheheadstocktogetherwitharodtoactasthestopDependinguponwhatyouaredoingitmaybeusefultohave

morethanonestopbareachwithitsownseparatestopblockInusethebarisinsertedintothemainblockasfarasthestopblock(if fitted)andlockedinplaceThefirststopbarcouldbeusedto facetheworkpieceandthesecond(shorterbar)couldbe used to turn along the diameter while a third bar couldpositionthepartingofftoolAnalternativeadditiontothestopbarcouldbeawasher(orwashers)ofknownthicknessplacingthewasher(orwashers)onthebarwillextendthestoppositionbythethicknessofthewashersusedAusefultipistostampanumberonthestopblockssothat

eachone isnumberedYoucouldalso stamp the thicknessonthewasherssoyoudonrsquothavetokeepmeasuringthemandjustpickthemupinthecorrectorderItsavesalittletimeandhelpsavoiderrorsThe whole point about using a stop is the consistency of

positionwhichistransferredtotheaccuracyofthecomponentit gives Once you have learnt to use a stop youwill wonderhowyoumanagedwithoutitEvenforone-offcomponentsitwillsaveyoutimeForatypicalone-offsteppedshaftsetthestopsotheturning

tooljustfacesthebarandfaceoffMove the top slide along for the length of the turned step

requiredTurnthestepYounowhaveastepontheendofthebarofaknownlengthNofiddlingnomeasuringndashyouknowitiscorrectUsing the bed stop offers a simple way of doing repeat

turning of lengths and diameters in the lathe Stops are notlimited to production methods they are very useful formachiningone-offsaswell

A single stop bar will serve for much of the work you aredoingbutsometimesyouneedmorethanonestopTheanswerhereistousemorethanonestopbarinconjunctionwithastopblockEachbarhasitsownstopblockthatcanbetightenedupThenyoucaninterchangethestopbarsandeachbarcanbesettotherequiredlengthbyusingavernierorruleYoujustsetthetwostopblockstothedifferencerequiredandlockthestopbarintheholderasnormalWhenyouneedmorethanoneofeachitemitisveryeasyto

save time in theworkshop once the lathe is set up you canmake several items in quick succession A typical example ofthis type of production is a simple spacer Set a facing andchamferingtoolinonetoolholderapartingofftoolinanothertoolholderandadrillinthetailstockchuckThefacingtoolandparting off tool are in fixed positions to each other so it is asimplematter of drilling thehole facingoffwithone tool andparting off with the other As long as the gap between thepartingofftoolandthefacingtoolremainsconstantthespacerswill remain at the samewidth each time youmachine one ofthemTheeasywaytosetthethicknessofthewasheristofaceoff

theendofthebarbringthepartingofftooluptothefinishedface and lock the cross slide Wind the parting off tool backslightly so you can move the bar forward in the chuckMeasuring with the vernier calliperrsquos depth rod from therighthandfaceofthepartingofftoolbringthebaroutslightlylonger than is needed for the washer thickness Using thetailstock chuck drill the hole using a centre drill for the firstwashertoensurethedrill runstrueNowsetthefacingtool inpositionfaceoffthewasherandpartofffromthebarMeasurethe washer and adjust the facing tool either way so that thethicknessof thewasher iscorrectPull thebar fromthechuckslightlyfurtherthanthefacingtoolsothateachwashercanbefaced to lengthYoucanmakeasmanywashersasyouneedall of the same thickness The same applies to nuts and anyothercomponentthatneedstobeasetlengthIfmakingboltsor screws theprinciple is thesamebutyou

willneed to turndown thediameter tobe threadedThis timethedifferencebetweenthepartingofftoolandtheturningtoolisthethicknessoftheheadInordertofacetolengthhoweverawasher of a known sizemust be inserted between the stopblockandthecrossslideThiswasherwillbethelengthoftheturneddownportionofthecomponentIfyouwanttomakeabatchofcomponentsbutdonrsquotwantto

keepmovingorchangingtoolsyoucanmachinethebatchonestepata timedoingoneoperationoneachcomponentbeforedoing the next operation on all the components Repeat thisuntil the complete batch ends up as completed componentsYou have the added advantage that the components willprobablyallbethesameshapeandsizesomethingthatisnotalwayspossiblewhenmachiningeachcomponentindividuallyTo make a batch of components such as washers to the

samethicknessisquitesimpleSetupapartingtooltopartoffthe components and set up a facing tool to face thecomponentsThedifferenceinpositionbetweenthefacingtooland the parting toolwill be the thickness of thewashers Youcanadjustthethicknessofthewasherbymovingthefacingtoolbackwardsor forwardswith the topslide toadjust it The rearpartingofftooldoesnotmoveotherthantopartoffthewasher

Makingwasherstothesamelengthusingfixedpositiontools

TAILSTOCKTURRET

AnotherusefulaccessoryisthetailstockturretThisisarotatingheadthatisusuallysetbackatanangleItfitsintothetailstockof the lathe and has multiple stations to take different toolsoftenitwilltakefourfiveorsixtoolsThebenefitofthisisthatitcanhaveabarendstopacentredrilladrillacountersinkatapandadieoranycombinationthereofallsetupreadytousein sequence The tools normally fit into holes bored into theturretToavoidtoolsstickingouttoofar it isbesttousestubdrillsinsertedintoroundbarsthatfitintotheturret

Anindexingturretthatfitsdirectlyintothetailstockofthelathe

YoucaneitherdrillandtaptheroundbarsoruseLoctite tosecure the drill in the round bar You can also buy roundadaptorswithaJacobschucktapermachinedontheendtotakechucksAnothermethodoffittingchucksistodrillandtaptheround bar to take chucks with threaded extensions ThesechuckscanoftenberetrievedfrombrokenBlackampDeckertypedrillsDieholderscanslideonapieceofroundrodintheturretFor

smaller diameter threads you can stop the die from rotatingusing your hand There is no need to reverse the lathe whenthreading just stop it and spin the die off by hand the samegoes for taps For larger taps and dies you can use a shorttommybartostoprotationbutmakesurethatthetommybarpositionisclosertotheworkthantheendofanyofthedrillsorthetommybarwillsnapthedrillsifyouletgoofitorifthetapordiejamsupYoucanalsomakeorbuyarunningcentretofitintotheturrettosaveremovingitwhenyouneedtousealathecentreOnlydothiswithsmallorlightworknotheavybarsorfor largecutsWhenused inconjunctionwithagoodbedstop

system a tailstock turret becomes a very versatile productionfacilityTheturretcanbemademoreversatilebyfittingalever-feed

tailstockattachmentoracapstan-style feedattachmenttothetailstockturretEitheroftheseattachmentswillmaketheturretveryfastinoperation

Anindexingturretsetupwithastopandacentredrill

Standardlever-feedtailstock

SECONDOPERATIONWORK

SECONDOPERATIONWORK

Sometimes it is necessary to do second operation work on apart-machinedcomponentUsually thiswillbeon theoppositeend to the one already turned There are two main ways ofholding theworkpiece in the correct position for furtherworkthechuckbackstopandsoftchuckjawsThechuckbackstopisquitesimpletomakeItconsistsofa

draw-incolletapieceofplainbarforthestopabitofthreadedbar a nut and a top hat collar The collet goes into the lathemandrelandisdrawninbythethreadedbarThethreadedbargoesthroughthemandrelandislockedinplacebythenutandthe tophatcollarat the left-handendThe tophatcollar is toprotecttheendofthemandrelThestopbarfitsthecolletandispositionedsothattheworkislocatedattherightdepthinthechuckThismeansthateachcomponentput intothechuckupagainstthebackstopwillalwaysbeheldinthesameposition

Capstan-stylelever-feedtailstock

Adraw-inbackstop

Softjawswithhexagonsadded

The secondmethod is to hold the component in soft jawswhich are bored out to hold the component (see Chapter 5)ThismeansthecomponentshouldrundeadtrueandeachonewillbeheldinthesamepositionreadytobemachinedSoft jaws tend to be used for larger components while the

backstop ismore likely tobeused forbarworkYoucanboltextension pieces to soft jaws to hold larger diameters orextensions can be machined to make a nest to take largercomponentsWhensoft jawsarewornoutandfaceddowntoo

lowforfurtheruseyoucanboltapieceofhexagonbartoeachjawtogivethemanewleaseoflifeIfyouhaveabatchofthreadedcomponentstofinishonthe

second end you can screw them into a bit of bar held in thechuck If theyarehexagonbolts just tightenup lightlywithaspanneriftheyareroundheadandtheheadwillbemachinedlateryoucouldtightenanduntightenthemwithapairofpliersThe more production work you do the more varied the

methods you will learn and the quicker you will makecomponentstoahighstandardofaccuracyA sensitive drilling attachment can be very useful when

drillingwith tiny drills The feed is by hand which gives it itssensitivity The attachment can also be used for small tapswherethetravelisfairlyshort

Machiningscrewheadsbyholdingthescrewinathreadedmandrel

Asensitivedrillingattachmentthatfitsintothe

tailstockchuck

ThisVeeattachmentisusedforcrossdrillingandcanbeusedintheheadstockorthetailstockofthelathedependingonthelengthofthebartobecrossdrilled

ThisisarevolvingtaperforthetailstockIfyoufitadrillchucktoityoucanuseitasarunningsupportforsmallbarwhereacentreisnotpermissible

12TapsDiesandScrewcutting

Thischaptershowshowtousetapsanddiestocutinternalandexternal threads in the lathe Italsoexplainshowyoucansetupasimplegeartrainandcutascrewthreadwiththehelpofascrewcuttingdialindicator

Atypicaldie

CUTTINGTHREADS

Threadcuttingeither internalorexternal isan importantpartoflearningtousealatheThepurposeofathreadisusuallysothatyouareabletoholdpartstogetheralthoughotherusesforthreadssuchasleadscrewsandfeedscrewsformachinetoolsareoftencalledfor

Safetyhasalreadybeencoveredindepth(seeChapter2)butafewextrawordsonsafetywhenthreadcuttingarecalledforWhen tapping a hole or threading a bar from the tailstock atailstocktapordieholderisoftenusedForthesmallerthreadstheholdershaveaknurledbodyandrotationcanbestoppedbysimplyholdingthebodyoftheholderinyourhandAslongasyoukeepyourhandawayfromthechuckandany

sharp lathe tools on the cross slide you should be fine (ifpossible remove either the tool holder or the tool itself )Providedthereisnothingtocatchorsquashyourhandonyoucan hold the knurled tap or die holder in your handwhile thelathe is running slowly under power and releasing the holderwhen the full length of the thread is cut or the pressurebecomes too great for you to stop the rotation (By slowly Imeaninveryslowbackgear)For largerthreadshoweveratommybarwilloftenneedto

beusedtostopthetapordieholderfromrotatingWhenusingthe tommy bar to prevent rotation do not under anycircumstances use the lathe under power Instead switch themachinerightoffandunplugit ifpossibleTurnthetapordieholdingthetommybarwiththerighthandandstopthechuckfromrotatingwiththelefthandThere are already many published charts providing thread

data covering such factors as tapping hole sizes minimummaximum and effective diameters as well as pitches andthreadsperinchIwillnotbeprovidingthemherebutwishtopoint out that tapping size drills can vary with the materialbeingcutWhenIamtappingsmallsizes instainlesssteel forexampleIusuallydrillthehole0004in(01mm)largerthanthefigurestated in thechartThisway Iam less likely tobreakatapinthehole

HSSorCarbonSteel

TapsanddiesareusuallymadefromcarbonsteelorHSSHSStapsanddiestendtoremainsharpformuchlongerthancarbonsteeltapsbutcarbonsteelisusuallycheaperNewcarbonsteel

tapsanddieswillprobablybefineforsmallerholesandsoftermaterials but wherever possible HSS should be your firstchoice Second-hand taps and dies are sometimes availablefromtoolshopsoroneBaybutinmyexperiencetheyareoftenbluntandnotworthbotheringwith

Lubricants

Whether tapping threading with a die or screwcutting it isnormallyessentialtousealubricantevenonbrassForbrassaluminium and bronze kerosene (paraffin) or white spirit isgenerallyusedandcanwithadvantagehaveasmallamountofcuttingoiladdedFor steel and stainless steel amodernpaste-based tapping

compound or cutting oil should be used This can also beappliedtocopperthismetalcanbestickybuttakeiteasyandall should gowell I also use paste or cutting oil on cast ironAlthoughmostrecommendationsaretocutcastirondryIhavefoundalubricanttobeveryhelpful

Screwthreadpitchgauge

ThreadGauges

When following a published design you will probably use thethread sizes as recommended by the designer If you are

making a thread to match an existing thread however youneedtofigureoutwhattheexistingthreadisThisiseasiesttodoonanexternalthreadIfyouhaveonlythenuttrytofindaboltthatwillfititandusethattocheckthethreadIfyoucanrsquotfindamatchingboltandtheholeinthenutisbigenoughyoucouldtrypressingabitofplasticineintotheinternalthreadandmeasuringthatTomeasuretheexternalthreadweneedtodeterminethree

thingsusingathreadpitchgauge theoutsidediameterof thethread the pitch of the thread and the thread angle Thesethree checks will probably be sufficient to decide what thethreadactuallyisBritish threads such as British Standard Fine and British

Standard Whitworth and also the Model Engineer threadsystemhaveanangleof55degreesAmerican threads such as UNF (Unified Fine) UNC (Unified

Coarse) UNEF (Unified Extra Fine) ANF (American NationalFine)ANC(AmericanNationalCoarse)are60degreesasisISOmetricUnusually theBritishStandardCycle thread is also60degreesThe other thread youmight come across is the BA (British

Association)threadThishasathreadangleof47frac12degreesandismetricbasedThelargestBAthreadis0BAwhichhasa6mmdiameterwith a 1mmpitch TheBA series godown to 22BAbutinpracticeyouareunlikelytocomeacrossanythingsmallerthanabout14BA

TAPS

TappingistheprocessofcuttinganinternalthreadwithatapFirst a hole is centre drilled and drilled in the workpiece Irecommend that you give the top of the hole a 90-degreecountersinktogivealead-intothetapandalsotostopthetapfromthrowingupaburrontothefaceofthework

Setofhandtaps

TypesofTap

The many types of tap can be divided into hand taps andmachinetapsHandtapsarenormallyheldinatapwrenchbutcan be held in the lathersquos tailstock chuck or a purpose-madetailstocktapholder

Close-upofahandsecondtap

WhentappingbyhandstartthetapuntilitstartstobiteandgiveitanextraturnorsoReversethedirectionofthetapforaturn to break the chip Continue forward for a couple of turnsand then reverseasbeforeContinue todepthor through theworkpiece by continually tapping a couple of turns reversingandcontinuingforwardThisshouldclearthechipsandpreventthetapfrombreakingIfthetapgetshardtoturntakeitrightoutoftheholetoclearanyswarfaddsomemorelubricantandcontinuetappingA set of hand taps will normally comprise a taper tap a

secondtapandaplugtapUsuallyyouwillstartaholewithataper tap This is a tap where the outside of the thread isreducedtowardsthepointbygrindingitonataperThistypeoftap can be used to start the hole but if the hole goes rightthrough the work it may be possible to screw the tap rightthroughtheholesoformingafullthreadrightthroughIfthetapertapistooshortorifyouaretappingablindhole

youneedtofollowthetapertapwiththesecondtapwhichhasmuch lessofa taper In fact itonlytapersrightat thestartofthetapTheplugtapisfinallyusedusuallytofinishoffablindhole

Theplugtaphasnotaperonitjustashortlead-inontheendBetween the three you should be able to tap themajority ofholesintheworkshopWhentappingblindholesitisbesttoworkoutthedepthand

fromtherethenumberofturnsneededforthetaptoreachthebottomoftheholeAsanexamplesaytheholeis9mmdeeptothepointThe tapenters2mminto theholebeforestarting tocutSo9mmless2mmgives7mmThepitchofthetapis05mm7mmdividedby05equals14sothenumberofturnstothebottomoftheholeis14Inpractice12or13turnswillbethemaximumneededWhen tapping blind holes make sure that all swarf is

removedfromthebottomoftheholebeforestartingtotap

Selectionoftapholders

HoldingTaps

TherearetwomaintypesoftapwrenchthehandtapwrenchwhichisdesignedtobeheldwithbothhandsandtheTeetypetapwrenchwhichoncestartedcanoftenbeusedone-handedTapsusuallyhaveeitheracentreholedrilledintheshankor

theshankisgroundtoapointThismeanswecansupportthetapfromthetailstockeitherbyusingalathecentreorbyabitofbarinthetailstockchuckwithafemalecentreinitTeetypetapwrenchesoftenhaveafemalecentreintheendandcanbesupported on a running centreWhen the tap is supported bythe tailstock at one end and the hole in theworkpiece at the

otheritmustbeinlinewiththeholeintheworkpiece

Machinetap

MachineTaps

Themaintwotypesofmachinetaparethespiralpointandthespiral flute The spiral point pushes swarf downwards throughthe hole while the spiral flute pulls the swarf out of the holeSpiralflutetapsaremuchweakerthanspiralpointtapsandintheory should not be used for tapping by hand However inpractice you can often get away with hand tapping using aspiralpointtapifyouareverycarefulIneithercasethetapisdesigned for continuous rotation swarf being automaticallycleared so the regular reversal as with a hand tap is notnecessaryIf you are careful you can probably get away with using a

hand tap under power but only do this with a hand-held tapholderwhereyoucanquicklyletgoifthetapstartstostickYou can also getmachine taps thatwill cut a thread under

powerbyscrewingthroughthejobwithoutstopping

Spiralflutetap

SpeedsforTapping

Tappingspeedsshouldbe low lowbackgearspeedshouldbefineWhenyouhavetappedtheholetodepthorrightthroughtheworkpiecestopthelatheandspinthetapoutbyhandThiswillbequickerthanreversingthelathe

ThreadingfromtheTailstock

For small taps you can use the sensitive drilling attachment(seeChapter11)orifthetapislargeryoucoulduseaslidingtapholderThiscanbeassimpleasachuckmountedonataperat one endwith a parallel hole through the chuck shank ThechuckthenslidesonabarheldinthemaintailstockchuckForlargetapsyoucanuseatommybartostopthetapholderfromturningbutthetommybarshouldnotbesolongastofoulthelathebedoranyotherpartofthemachineifyouhavetoletgoInfactitisfarsaferifyoudonotusethetommybartothreadunderpower

DIES

Dies also come in carbon steel andHSS versions The outsidediameterofadieoftenvarieswiththesizeofthethreadbeingcutalthoughthediameterwillbetooneofasetstandardDiesusually have themakerrsquos name and the thread details on thefrontof thedieThis is theside that ispresented to theworkThediewill havea short lead-in if this isnot requiredon thefinishedthreadyoucanreversethedieanditwillcleanuptoashoulder

SlidingtapholderSlidingdieholdersarealsoavailable

When cutting a thread especially a small one it pays tomaketheinitiallengthofthreadlongerthanthatrequiredThisissoyouhaveabitat thefronttoplaywithtogetthethreadright Then you can part off the excess length leaving a goodthreadoftherequiredlengthDies are usually split so you can adjust them to cut a size

threadIdeallyyoushouldhaveadieholderforeachdiesoyoucansetthedietocutsizewithouthavingtoresetiteverytimeyouchangethedieThedieshouldbesetsothatitcutsasizethreadinonepassDie nuts are often hexagonal in shape They are used to

cleanupanexistingthreadthat isdamagednot tocutanewthreadfromscratchFor each thread you are going to cut you should make a

home-madegaugetappedwithyourowntapWhenyoucutthethreadanditfitsthisgaugeyoushouldthenhaveagoodbutnottightorloosethreadYoushoulduseatailstockdieholderwithaslidingbodywhen

threadingfromthetailstockasthiswillholdthedietruetothethreadIdeally the tailstock die holder should be knurled and also

haveatommybarholeforeaseofuseThe speed for threading with a die in the lathe should be

quitelowamaximumof60rpmshouldbefineformostjobs

SCREWCUTTINGATHREAD

Whilecuttingathreadwithtapsanddiesisperfectlyadequatefor most applications the ability to cut an accurate screwthreadbyusingthelatheisaveryusefulfacilitytohaveIfthethread is large or non-standard taps and dies may not beavailable or they may be so expensive as to be out of thequestionforuseintheamateurrsquosworkshopVariouspitchesofthreadcanbecutbythesimpleexpedient

of changing the configuration of the change gears or alteringtheleversonthescrewcuttinggearboxifoneisfittedWewillconcentrate on a lathe with change gears if you have ascrewcutting gearbox please refer to the manufacturerrsquoshandbookMost lathes that youwill comeacross are likely to have an

imperialpitch leadscrewThiswillbeapitchofsomany teethper inch (TPI) Typically this will be 4 or 8 TPI although otherpitchesareavailableForourexamplewewillbeusingalathewithan8TPI leadscrewandasetofchangewheelscomprisingthefollowingnumbersofteeth2times202530353840455055606570and75

SETTINGUPTHECHANGEGEARS

Letrsquostakeatypicalthreadpitchof20TPIForeveryturnofthemandrel the leadscrew needs to move forward 120in Thismeans we have to set the change gears so the mandrel toleadscrewturnratio iscorrect Inpracticethemandrelgear islikely tobe20 teethand this is unlikely to change nomatterwhat thread we are cutting This means we will change theleadscrew gear which has to have the correct ratio to themandrelTheTPIwewishtocutis20usingaleadscrewwithapitchof

8TPI20dividedby8givesusaratioof251Thismeansthatthe mandrel gear needs to rotate at 25 times the leadscrewgearAsthemandrelhas20teeththeleadscrewgearneedstobe25times20teethwhichisa50toothgearInpracticea20toothgearanda50toothgearmaybetoosmalltotransferthedrive from the mandrel to the leadscrew and intermediategear(s)willneedtobeusedThese gears are called idler gears and they can have any

number of teeth Youmay think these idler gears change theratio of the mandrel to the leadscrew but they do not Theysimply transfer the drive from the mandrel gear to theleadscrew and the ratio stays the same This concept can behardtograspsoIwilltrytoexplainitsimplySay the mandrel gear does one turn This makes the idler

gearorgearsmoveexactly20teethandthisinturnmovestheleadscrewgearexactly20teethAsyoucanseetheratiodoesnotaltertheleadscrewgearmoves20teethforevery20teeththemandrelgearmovesandtheratiostaysthesameThistypeofset-upisknownasasimplegeartrain

Simplegeartrain

Compoundgeartrain

Letuslookatanothercommonthreadpitch32TPITheratioofleadscrewtoTPIis41(8times4=32)Sotheleadscrewgearneeds to be themandrel gear 20 teeth times 4 = 80 teethLookingattheavailablegearswedonrsquothavean80toothgearThismeanswewillhavetouseadifferentmethodtogetour41ratioWithamandrelgearof20teethwecouldusea40toothto

give us a ratio of 21 We are now halfway there but needanotherpairofgearswitha21ratioWedohavea30anda60

toothgearsothiswouldgiveusoursecond21ratioWecouldnot set these gears up as in the previous example howeversince the two intermediate gears would just act as idlers andtheratiowouldbe2150percentoutfromwhatisrequiredWhatwewouldhavetodoismountthe40toothandthe30

tooth gears on the same spindle so they rotate at the samespeedaseachother(The20toothgearmustdrivethe40toothgearandthe30toothgearmustdrivethe60toothgearinthisorder)Thiswouldgiveusthecorrect41ratiothatweneedAswehavemountedtwogearsononespindlethisisknownasasinglecompoundgeartrainDependingonyourlatheyoumayneedanidlergearbetweenthe30toothgearandthe60toothgearAgainthiswillnotalterthegearratiosYou can also have double compoundgear trainswhere two

lots of gears are mounted together on two spindles This istaking us into complicated territory however and I will referreaders to the screwcutting chart provided for their particularlathe Ifyour lathedoesnotcomewithascrewcuttingchartasearchon the Internet should findone that you candownloadandprintoutThemost likely application of double compound gear trains

would be to cutmetric threads with an imperial leadscrew orimperialthreadsover60TPII have tried to keep this explanation of setting up

screwcutting gears simple and the maths to a minimum Theexplanationgiventogetherwiththescrewcuttingchartforyourlatheshouldbemorethansufficienttogetyougoing

ExternalscrewthreadtoolmadefromaCoventry

diechaser

CUTTINGTHETHREAD

The speed for screwcutting should be about mid-back gear ifyouhaveitpreferablysomewherearound30ndash40rpmatmostTherearetwomainmethodsofscrewcuttinginthelatheThe

firstoneinvolvesthetopslidesetparalleltotheworkandintheothermethodthetopslideissetonanangletothework

Externalsinglepointscrewthreadtoolsettinggauge

Cuttinga20TPIThreadwiththeTopSlideParallel

For a 20 TPI Whitworth thread the pitch is 0050in and thethreaddepthisaconstant064ofthepitchsothethreaddepthis 0050 times 064 = 0032in This is the depth the cross slideshouldbewoundinWhilethedepthofthreadis0032inyoualsoneedtomove

the top slide forwardat eachpass Fora standardVee threadthisneedstobehalfthein-feedofthescrewcuttingtoolsoyoumovethecrossslideinby0010inandmovethetopslidealongbyhalfthis0005in

Cuttingascrewthreadwiththetopslidesetparalleltothelathe

Cuttingascrewthreadwiththetopslidesetatanangletothelathe

Theendresulta20TPIfinishedthreadbeforetidyinguptheendandundercutting

Cuttinga20TPIThreadwiththeTopSlideatanAngle

This angle will vary according to the thread being cut but itshouldbeabout1degree less thanhalf the includedangleofthethreadforaWhitworththreadof55degreesforexampletheangleshouldbehalfof55degreesminus1degreegiving265degreesNotethattheangleistakenwiththetopslidesetat90degreestotheworkWiththetopslidehandlefacingyou(at90degreestohowit isnormallyused)rotatethetopslidethe required number of degrees (265) to the right Beginnersoften rotate the top slide 265 degrees to the left from thenormalpositionwhichwouldgivean included threadangleof127degreesThisisclearlywrongBecausethetopslideissetonanangleyouwillneedtofeed

thetopslideinfurtherthanifthetopslideissetparalleltothelatheYoucan findthe increaseddepthof threadbyusingthefollowingformula

c=bcosineofA

whereAistheanglecalculatedathalftheincludedthreadangleminus1degreegiving265degreesb is thedepthof thread(forWhitworththreadsthisis064timesthepitch)andcisthecalculatedangulardepthofthreadFor a 20 TPIWhitworth thread the pitch is 0050in and the

threaddepthisaconstant064ofthepitchsothethreaddepthis0050times064=0032inThecompensateddepthofthreadisthen0032individedbythecosineof265degrees=00357

UsingtheThreadCuttingIndicator

With an 8 TPI leadscrew if the thread being cut has an evennumber of threads the leadscrew can be engaged at anypositionof the threadcuttingdial indicator If the thread isanoddnumberyoushouldusethesamenumberoranyalternatenumberthatisoneorthreetwoorfourForthreadswithahalfpitch always use the same number For metric threads orpeculiar numbers do not disengage the clasp nuts withdrawthescrewcuttingtoolandreversethemotoruntilthetoolgoesback to the start If the thread is an exact multiple of theleadscrewtheclaspnutscanbeengagedatanypositionIfindoubtalwaysengageatthesamenumberoneIttakes

verylittletimetotraversetheextradistancerequiredFor leadscrews other than 8 TPI please refer to your lathe

manual

AcknowledgementsandUsefulContacts

I would like to thankMy TimeMedia Ltd (Publishers ofModelEngineer and Model Engineersrsquo Workshop) Ken Wilson TonyJeffreeandTranswavePowerCapacitorsLtdfortheuseoftheirphotographs

USEFULCONTACTS

UnitedKingdom

ArcEuroTradeLtd10ArchdaleStreetSystonLeicesterLE71NATelephone01162695693Fax01162605805EmailinformationarceurotradecoukhttpwwwarceurotradecoukSuppliersofmachinetoolsandaccessories

ChesterMachineToolsHawardenIndustrialParkHawardenChesterCH53PZTelephone01244531631EmailsaleschestermachinetoolscomhttpwwwchestermachinetoolscomSuppliersofmachinetoolsandaccessories

CowellsSmallMachineToolsLtdTendringRoadLittleBentleyColchesterEssexCO78SH

1BuyingYourFirstLathe

WHATSIZEOFLATHEDOIREQUIRE

ThefirstthingtoconsiderwhenbuyingalatheisthesizeoftheworkthatyouwanttodoWhatisthelargestdiameteryouwillwanttoturnonitandwhatisthelongestlengthyouwillneedtoturnA3frac12times18in(90times457mm)lathewillallowamaximumdiameterof7in (178mm) tobe turnedover the lathebed thelatterfigureisknownastheswingInpracticethoughthisisatheoreticalmaximumas it is stillnecessary toholdandclampthe article being turned The swing over the cross slide isusuallymuchsmallertypically2in(50mm)Many lathes however aremanufacturedwith a gapbed at

the headstock end to enable short items of a large diametersuchaslocomotiveortractionenginewheelstobeturnedLathes are also sometimes available as standard and long

bed lathes The long bed lathe as the name suggests allowslongermaterial to be turned within the capacity of the latheWhen turning longermaterial the diameter will be limited bytheswingoverthecrossslideThiswillbealotsmallerthantheswingoverthebedIfbuildingamodelsuchasatractionengineoralocomotive

the deciding factor for the size of lathe is likely to be thediameterof the largestpairofwheels thatneed tobe turnedBefore deciding on the size of lathe required you shoulddetermine the size of the largest diameter and the longestlength of material that needs to be turned Another factor indeterminingwhat lathe tobuy is theavailabilityof sparesand

accessoriesisthecompanystilltradingwillitstillbetradinginthe future and are there large amounts of secondhand partsandaccessoriesavailablefromtooldealersoroneBay

Atypicalinvertertoconvert240voltssinglephaseto240volts3phase

LATHEELECTRICS

Single phase electric is where the lathe plugs into the mainssupplyinyourhouseThemotorwillhavetheusualliveneutraland earth leads Lathes supplied for factory use usually havethree phase motors and require three live wires each of adifferentphaseThinkofaphaseasan incomingwaveon theseashore three successive waves make up the three phasesneededEachphaseisthesameastheprecedingonebuttheyareoutofsyncandallpeakatadifferenttime

Aforwardreversecontrolboxforaninverter

Convertersandinverters

Youcan runsome3phasemotors fromasinglephasesupplyviaaconverteroraninverterThemotor informationplatewillusuallysay240volts440voltsif it iscapableofrunningonaninverter Inside the motor there will be changeover tags tochange the motor from 440V down to 240V Follow theconverterinverter manufacturerrsquos instructions for furtherinformation It isnotusuallyverycomplicatedto runa240V3phasemotor from an inverter and thiswill give a quieter andsmoother running motor than a single phase supply canprovide This usually requires some simple programmingexplainedintheinverterrsquosinstructionsanditusuallytakesfiveminutestogetthemotorworkingproperly

ThismotorispartoftheinverterpackageshowninthepreviousillustrationNowiringisinvolvedasthemotorleadplugsstraightintotheinverterbox

Theinverterrunsataconstantvoltagebutthespeedofthemotor will change as the frequency is raised or lowered Isuggest limitingyour inverter from full speed tohalf speed sothatthefanstillcoolsthemotorandstopsitfromoverheatingyoucanthenusethebeltstochangethemainspeedstepsasusual(Ifyoumustuseveryslowrunningitispossibletoaddaseparatefansuchasacomputercoolingfantogiveconstantairflow) Most inverter suppliers offer a forwardreverse andspeedcontrolboxthatcanbesetupinaconvenientpositiononthe machine These are well worth fitting for convenience inuse

Thisinverterisdesignedformountingonthefrontofthelathe

While inverters are designed to run only onemachine youcangetconverterstopowermorethanonemachineatatimeDependingonthesizeandpoweroutputconverterscostaboutthreetofourtimesasmuchasaninverterTherearetwomaintypesofconverterRotaryconvertersare

designedtorunmorethanonemotoratatimeThisis ideal ifyouwanttorunmorethanonemachineortwomotorsononemachineforexamplethemainmachinemotorandperhapsanauxiliary motor that drives the machinersquos coolant pump orpowerfeedsystem

Arotaryconvertercapableofpoweringmorethanone3phasemotor

ThesecondtypeisthestaticconverterwhichisdesignedtorunonemotoratatimeThereisofcoursenothingtostopyouusingthestaticconverteronmorethanonemachinebyfittingasuitablefemaleelectricalconnectortothestaticconverterandmatchingmaleconnectorstotheindividualmachinesThiswayyoucanconnectthestaticconvertertoonlyonemachineatatime

Thisstaticconverterissuitableforpoweringone3phasemotorIfyoufitasocketontheoutputhoweverdifferentindividualmachinescanbepluggedintoitoneatatime

Theelectricalloadingonrotaryorstaticconvertersmustnotexceed theirmaximumrating If indoubton the loadcapacityneeded to run your machine(s) you should consult the

manufacturerorsupplieroftheconverter

AnearthleakagetripisidealforquicklyeliminatingamotorwheretheelectricalinsulationisbreakingdownItisusefulfordetectingcertainelectricalearthingfaultsbutshouldnotbeusedasaguaranteeofelectricalsafety

Simpleelectricaltestingandsafety

Whenbuyingasmallsinglephasesecondhandlathetakewithyouanearth leakage testerof the typeused for lawnmowersandothergardentoolsIonceboughtaUnimat3lathetookithomeandpluggeditinItkeptblowingtheearthleakagetripinthefuseboxeventhoughithadworkedperfectlyatthesellerrsquoshouseIsolditonatalossbutthebuyerdidknowtherewasaproblemwiththeelectricsIt is most important that the metal parts of any lathe are

connectedtotheearthwirewhichisinturnconnectedtoearthMake sure that themotor frame is also connected toearthassome motors have dampening rubber mounts that insulatethem from themachine itself If in doubt about any aspect ofelectricalinstallationpleaseconsultaqualifiedelectrician

Acontinuousbedisidealwhenworkingwiththefaceplateorwithcollets

LATHEBED

Thelathebedisthebackboneoftheentirelatheandisthepartthat is mounted on the bench or stand There are two maintypesoflathebedtheplainbedandthegapbedTheplainbedisusuallycontinuousallthewayalongitslengthwhilethegapbedhasas itsnamesuggestsagap in thebedThis isnotaliteralgapbutasteppedsectionthatallowsbiggerdiameterstobeturnedthanyouwouldotherwisebeabletoturnonaplainbed latheThisgap isameansofmakinga lathesmaller thanwouldberequiredforaplainlatheabletoturnasimilarsizeof

componentSome continuous lathe beds have a section next to the

headstock that can be removed to increase the diameter thatcanbeturnedThisfeatureisusuallyonlyfittedtolargerlathessuchasaremostlyfoundinfactoriesSome lathes have hardened beds although most are just

plaincast ironTherearethreemaintypesofbedwayscalledshearstheplainflatbedwithsquarewaysabedwithaflattopand a 60 degree dovetail at each side and a bedwith raisedandinvertedVeewaysOnthelastofthesethetailstockusuallyrunsononesetofVeesand thecarriageonadifferent setofVees resulting in lesswear to themain slidesWidebedsarebetterandmoreaccurateasthelathecarriageislesslikelytotwistonawidebed

Close-upviewofatypicallathebedwithagapAgapbedlathehasalargerturningdiametercapacitythantheequivalentsizedcontinuousbedlathe

Someveryearly lathessuchas thosemadebyDrummondhad a round bed Although they worked well there is noadjustmentforwearinthelathebed

TheMyfordrangeoflatheshasasquareformofbed

ThistypeofbedhasaflattopwithaninvertedVeeateachsideTheVeesareusuallysetat60degreesbutcanvarywithdifferentmakers

The Unimat SL lathe was sold for many years and manysecondhandexamplesarestillavailableThismodeldiffersfrommostlathesinthatithastwosteelbarsasabedThisisnotaproblemhoweverastheUnimatisintendedonlyforverysmallandlightweightmodel-makingworkandthereistheadvantagethatthebedcanbereplacedbyfittingnewbarsWhen buying a secondhand lathe it is most important to

checktheconditionofthebedYouneedtomakesurethebedis reasonably free from dings rust and hacksaw marksHacksawmarksneartheheadstockareoftencausedbysawing

offworkwhile it isheld inthechuckdingsareusuallycausedbydroppingthechuckonthelathebedwhenscrewingitonoroffthemandrelAsimplechuckboardplacedonthebedwhilefittingorremovingthechuckwillprotectthebedItisalsoidealfor protecting the bed when filing or hacksawing work in thechuck

AlathebedwithraisedandinvertedVeesThecarriageusuallyslidesononesetofVeesandthetailstockslidesontheother

AmodernChineselathebedwithaninvertedraisedVeeThecarriageandtailstockusuallyslideonthesameVee

Wear ismost commonly found at the headstock end of thelathe as a result of machining many short components andrelatively few long ones Make sure the lathe carriage isproperlyadjustedattheheadstockandthenrunitalongasfaras you can towards the tailstock The carriage should bereasonablyfreebutnotlooseallthewayalongthebed

OldroundbedDrummondlathesarestillavailablesecondhandThisparticularexampleistreadledriven

AflatbedlathewithsquarebedwayssuchasaMyfordcanbe checked for wear on the lathe bed using amicrometer orvernierCheckovertheworkingpartofthelathebedonwhichthe carriage slides rather than the part that is not used forguidance Check both the width and the thickness of the bedwaysThetailstockshouldalsobeagoodslidingfitonanyguiding

surfaces Wear is most likely to be found on the tenon thatslidesbetween thebedwaysAworn tenoncouldprobablybereplacedbutthereisnotmuchyoucandoifthetenonguidesarewornTheonlyway to fixawornbed requiresacompletebedregrindThisislikelytobeexpensivesoitwouldbebettertolookforanunwornlatheDecentunwornlathesareouttheresincemanymodelengineersmayhaveboughtthemnewfortyorfiftyyearsagoandhardlyusedthem

TheUnimatSLisaverypopularsmalllatheItsbedconsistsoftwosteelbarsthatcanbereplacedveryeasilywithsilversteeliftheygetwornormorelikelywhentheygetrusty

Asimplewoodenchuckboardwillprotectthelathebedfromdingsandhacksawmarks

LATHEHEADSTOCK

Theheadstockisthelargecomponentmountedattheleft-handside of the lathe bed It needs to have good bearings An all-gearedheadwillalmostcertainlyhaveballorrollerraceswhilethe older type of lathe for amateurs may well have plainbearings either phosphor bronze or whitemetal These areperfectlyadequatebutyoushouldmakesurethere isnowearinthemSomelathesalsohaveamandrelthatrunsdirectly inbored holes in the cast iron headstock casting Plain bearingswillbeperfectlysatisfactoryas longasadequate lubrication isused

Close-upviewofaMyfordheadstockonanML7RNotethelargebronzebearingatthefrontTheearlierML7latheshadwhitemetalbearingsalthoughtheC7capstanhadbronzebearingsandahardenedlathespindle

Tocheck forwear in the lathersquosbearings fitachuck to themandrelandputadialtestindicatorontopofthechuckGentlytry levering the chuck up and down by using a steel bar orsimilarheldinthechuckYouarelookingforminimalmovementhereespeciallyonaheadstockfittedwithballraces

CheckingthelathebearingsforwearAnymovementupanddownindicateswearinthebearing

The mandrel is mounted in the headstock and is usuallythreaded to take a chuck or faceplate The lathersquos mandrelshould not move back and forth in the bearings If it doeshowever itwillprobablybepossibletoadjust ittocorrectanyendwise movement The mandrel should not be too stiff butshouldturneasilybyhandWhentestingalathemakesuretheheadstockbearingsare

correctlyadjustedsothatwherepossiblethereisnoplaySeta tool up take a trial cut alonga length of bar and check forchatter If you are using a correctly set tool and a suitablespeedchatterisasuresignofwornbearings

Manylatheshaveathree-orfour-stepdrivepulleyasthesecondstageofthedrivechain

POWERDRIVE

Manylatheshaveathree-orfour-steppulleyonthemandreltotake the drive from a similar pulley on the countershaft Thecountershaft is in turn driven from the motor which is oftenmounted at the back of the headstock and completes theintegral drive system that is so popular on most amateursrsquolathes

Thisparticularlathehasatwo-stepmotorpulleyandcountershaftwhichdoublestheavailablespeeds

SpeedchartonthebeltguardofaMyfordML7Rlathe

AfewlatheshaveaclutchfittedasstandardorasanoptionalextraTheclutchsaveshavingtostartandstopthemotorwhileitisrunningThishelpstostopwearandtearonthemotorandelectricalsystemAdifferenttypeofclutchsystemtheTriLevaspeedselector

wasonlyfittedtoMyfordML7orC7lathesThishasthreeleversfor setting threedifferent speedsDependingon the leveryoudepressyougetahighmediumorlowspeedIfyoupressoneof the levers downwhile another is right down the first leverwilldisengagethesecondsostoppingthemandrelfromgoinground If the lathe is switched off and all three handles aredepressed the mandrel is locked preventing rotation This isusefuliffilingorhacksawinginthelathe

TheclutchisnormallymountedinsidethelargecountershaftpulleyItisusuallyoperatedbyaleverattheright-handsideoftheheadstockattachedtoapushrodthatpassesrightthroughthecountershaft

TheMyfordTriLevaattachmentwillonlyfitML7andC7lathesandisnotsuitableforML7RorSuper7lathes

Therehasbeenatrend inrecentyearstodoawaywiththecountershaftandpulleysystemandtoreplacethemotorwithavariable speed one with an electronic controller This isacceptable except that at low revolutions it does not providethe torque that can be obtained from a countershaft systemThereisalsothedisadvantagethatthereisnowaytodrivethelatheifthecontrollercircuitboardfailswhereasyoucanjustfita new one if the belt breaks The board could of course befixed provided that a circuit diagram is available and theelectronic components can be identified Sometimes thecomponents are marked with internal house numbers ratherthan commercially recognized part numbers that can beorderedasareplacementfromacatalogueSomeboardsmighteven have the identification marks removed to make repairsalmostimpossible

ThethreadedendofalathemandrelisdesignedsothatthechuckbackplaterunstrueIfthechuckmountingfaceofthebackplateismachinedinsituthechuckshouldruntrueaswell

CHUCKMOUNTINGSYSTEMS

The threaded lathe mandrel nose is not by itself a suitablelocationforachuckorfaceplatesothenoseisusuallygivenaturned register on which to locate the chuck The chuck isscrewedrightontothemandrelovertheregisterandbuttsuptoaturnedcollartokeepthechuckrunningtrueTheothersideof the mandrel collar butts up against the main headstockbearingwhichusuallyactsasathrustfaceThemandrelisusuallyboredthroughandmachinedtotakea

MorsetapercentreforturningbetweencentresDonotputyourfingerineitherendofthemandreltocleanitwhilethelatheisrunningAneasywaytocleanthetaperintheheadstockiswithabottlebrush often sold in chemists to cleanbabiesrsquo bottlesAnalternativeisasoftfeltshotgunbrushdonotuseonemadefromwire

ThislathehasaplainregisterAccuracyreliesonthelathechuckbeingagoodfitontheregister

There are various systems of chuck mounting in useespeciallyon the larger lathesTheproblemwith thescrew-ontype with a register mentioned above is that the chuck orfaceplatecanunscrewwhenthelatheisrunninginreverseTheonly timeyoushould run this typeofmandrel in reverseveryslowly and without taking a cut is if you need to return thescrewcuttingtooltothestartofthethreadyouarecuttingAlternativespindlenosescanbeaplaindiscwitharegisterto

boltthechuckontooracamlockwherethechuckisheldontightlybyturningstudstolockthechuckontothemandrelTheplain discwith register relies on having chuckswith amatingregistertoworkproperly

AnAmericanstandardCamLockchuckmountingbackplateandCamLockchuckplatefittedtoachuckTheyareusuallyfittedtolargerindustriallathes

TheAmericanDstyleCamLocksystemeithertakesachuckor faceplate directly or it has a backplate that can have aregisterturnedonittosuittherequiredchuckAlthoughmanylathe mandrels with Cam Lock fittings have six holes thematchingchuckorfaceplateoftenhasonlythreelockingpinsThe advantage of both of the last two systems is that they

canberuninreversewithoutthechuckcomingoffthemandrel

Theleadscrewisdrivenfromthemandrelviaageartrain

SCREWCUTTINGGEARS

The left-hand end of the mandrel will often have a gearmountedonittodrivethechangewheelgearsandleadscrewThe mandrel gear usually drives a pair of gears called

tumblergearswhicharemountedona leveratthe leftoftheheadstock The direction of the leadscrew can be changed bybringingeitheroneortheotherintogearbyraisingorloweringaleverThereisusuallyacentralneutralpositionwhereneithergearisinmeshThissaveswearonthelathechangewheelsandleadscrew bearings as well as reducing noise while workingMandrelandtumblergearswillbediscussedfurtherinChapter12whenwesetupascrewcuttinggeartrain

A set of changewheels usually comprises about a dozengearsbutthiscanvarydependingonthemanufacturerThesechangewheels which take the drive from the tumbler gearsdown to the leadscrew are mounted on moveable studs toensurethegearsareinmeshwitheachotherDependingonthenumber of gears in the train the leadscrew will turn eitherclockwiseoranti-clockwiseThedirectionof the leadscrewcanbe reversed using the tumbler gears to enable right-hand orleft-handthreadstobecut

Oftentherearetumblergearsinthegeartrainthatcanreversethedirectionoftheleadscrew

YoucanusuallysetthegearstocutaveryfinepitchsothattheleadscrewactsasaselffeedwhenturningfromthesaddleIf you anticipate the need to do any screwcutting check thatthesuppliedscrewcuttinggearswilldotherangeofpitchesyourequire It has been known for certain lathes to be unable tohandle somecommonpitches a typical examplebeing26TPI(teeth per inch) A pitch of 26 TPI is often needed to repairmotorcycles and bikes made before the introduction ofmetrication

MakesurethatafullsetofchangegearsisincludedwiththelatheIfnottheyarereadilyavailablesecondhand

LEADSCREW

The leadscrew ismounted at the front of the lathe there areusuallybearings to support the leadscrewateitherendof thelathe bed It is used tomove the lathe saddle along the bedeither for a self acting feed or for screwcutting Some lathesalso have a graduated handwheel mounted at the right-handendoftheleadscrewforturningthemandrelbyhandSome of the larger lathes also have a separate feed shaft

whichisusuallyaplainroundshaftwithakeywaycutalongittodrivethesaddleusingafinefeedThissaveswearandtearontheleadscrewwhichisthenonlyusedforscrewcutting

Mostleadscrewscanhaveagraduatedhandwheelmountedontheright-handendoftheleadscrew

SCREWCUTTINGFACILITIES

Ausefulfeatureonanylatheistheabilitytocutscrewthreadsof different pitches Leadscrews come in different pitches acommon one being 8 TPI but many variations are fitted todifferent lathes including leadscrews with a metric pitch It isawkward tomachinemetricscrewswithan imperial leadscrewandviceversaSometimesmetricconversionsetsareavailablebuttheycanbehardtofindareusuallyexpensiveandrequirethe lathe to be changed over often using 127 tooth gearwheels This figure is derived from multiplying the metricequivalentof1in(254mm)byfivea127toothwheelisthusadirectconversiontoametricthreadonalathewithanimperialleadscrewA127 toothgear isusuallyvery large if itmatchesthepitchoftheremainingscrewcuttinggearsbutyoucouldusesmallergearswitha smallerDP (diametralpitch)but stillwith127 teeth Youwould also need amatching gear of say fiftyteethtogiveyoua2541ratio

Thislathehasbothaleadscrewforscrewcuttingandadriveshaftforthesaddleandcrossslidefeeds

Ascrewcuttingdialindicatorusuallymountedtotherightofthe carriage is a useful feature This is a small dial withdivisionsmarkedonitmountedonashaftTheotherendoftheshafthasagearthatmesheswiththeleadscrewandmakesthedial go roundWhen the clasp nuts are engaged the carriagemoves and as the gear moves at the same speed as thecarriagethedialstopsgoingroundWhen you engage the clasp nuts on the leadscrew the

positionwhereyouengagedependsonthepitchofthethreadbeing cut Some thread pitches allow you to engage at anydivision of the dial while others need to be engaged at aparticularpositionof thedialTheuseof thescrewcuttingdialindicator will be covered in Chapter 12 When using the finefeedyoucanengagetheclaspnutsatanymarkedpositiononthedialsoavoidingweartotheclaspnuts

AtypicalscrewthreaddialindicatorThisoneisengagedanddisengagedbylooseningtheboltandengagingthedrivegearwiththeleadscrew

LATHESADDLEANDAPRON

The saddle is thepart that slides on top of the lathebedandusually has the cross slide and top slide mounted on it Theapron ismounted to the frontof the saddleYoushouldmakesure there isnoplay in the saddle either sidewaysorupanddownandthatittravelsfreelyfromoneendofthelathebedtotheotherwithnotightspotsAtthefrontnearesttheoperatorthereisusuallyapairofclaspnuts(thesearesplitnuts)Thesecan be engaged or disengaged from the leadscrew forscrewcuttingormovingthesaddlealongwiththeleadscrewOncheaper lathes there is usually a solid nut that cannot bedisengaged

ThelathesaddleslidesalongthelathebedTheapronisboltedtothefrontofthesaddle

There is often a rack at the front of the lathe bed thatmatches upwith a handle and gears on the lathe apron Thiscan be used to move the carriage along the bed withoutwearingouttheleadscrewSomelatheshavethecarriagefeedwheel on the right but others have it on the left where hotswarfcanfallontoyourhandsThecheaperlatheshavenorackandrelyontheleadscrewtowindthecarriagebackandforth

ATee-slottedcrossslidemakesthesmalllathemoreversatile

CROSSSLIDE

On top of the carriage is the cross slidewhich canbewoundbackandforthacrossthelathebedWhenusingthecrossslideforfacingacrosstheworkthecarriageshouldbelockedtostopitmovingalongthebedLathesforamateurusearemorelikelytohaveaTee-slottedcrossslidewhilelargercommerciallathesare unlikely to have this facility The Tee-slotted cross slide isveryusefulespeciallyifyoudonrsquothaveamillingmachineYoucanboltworktothecrossslideformachiningusingacutterinthechuckorforboringworkpiecesthataretoolargetoswinginthechuckZero settingdials aredesirable for both the cross slide and

thetopslideTheyallowyoutosetthedialtozerowhichmakesiteasiertomeasuretheamountyouaretakingoffwithonecutInusewindthetooluptotheworkandtouchonsetthedialtozeroandwind the toolbackoff from theworkYounowknowwherezeroisonthetoolandcantaketherequireddepthofcut

withouthavingtoworkitout

Zerosettingdialsmaketurningandscrewcuttingtodepthveryeasy

Apairofzerosettingdialsreadytofit

LathescanbepurchasedwithimperialormetricfeedscrewsMostmodeldesignsareimperialbutmetricismakingheadwayandthismaywellbethewaytogoBewarelatheswithimperialfeedscrewsandmetricdialsTypically thesewillhavea funnynumber of handwheel divisions rather than a whole numberMostofthelathesyoumightcomeacrossareunlikelytohavea

power cross feed for facing This does notmatter as you caneasilywindthecrossslideacrossbyhandTheonlytimeIhavefound a power cross feed to be of use is when I had to faceacross a faceplate to true it up I have trued up similar sizefaceplatesbyhanditjusttookalittlelonger

Thetopslideismountedonthecrossslide

TOPSLIDE

ThetopslideismountedontopofthecrossslideThetopslideisnormallysetat90degreestothecrossslidealthoughitcanusually be swivelled around to various angles for turning ataperanangleorforscrewcuttingSomeofthecheaperlathesdonrsquothaveatopslideasstandardbutitisaveryusefulfeatureif you can get one The top slide should be able to rotateespecially for screwcutting but the top slide handlemay foulthecrossslideincertainpositionssocheckifthisisaproblemTheturningtoolisusuallymountedonthetopofthetopslideItcan either be clamped on directly usually with packing stripsunderneathorthetoolcanbemountedinatoolholdersuchasathree-orfour-waytoolpostoraquickchangetoolpostWewilllook at tool holding methods in Chapter 4 when discussingsettingupturningtools

TAILSTOCK

The component at the right-hand end of the lathe is thetailstock This usually has a handwheel to feed a drill into theworkbut leverfeedandcapstan-style feedingmechanismsarealso available You can lock the tailstock anywhere along thebed The tailstock has a barrel inside it that can bewound inandouttogivealinearmovementtodrillaholeinworkheldinthechuckThetailstockisusuallyboredtoaMorsetaperoftenof a similar size to the headstock so it can take accessoriessuchasdrillchucksmountedonaMorsetaperItcanalsotakeacentre for turningworkbetweencentres It is important thatboth the headstock and tailstock tapers are free frommarksscratchesandburrs

AlathetailstockwiththebarrelextendedNotethatitisnotusuallyaproblemifthechuckkeyisleftinthetailstockwhilenotinuse

Adjustment is usually provided between the base and themain body of the tailstock to allow for setting the tailstock inlinewith theheadstock Tailstocks canbe self ejectingwherethetool isextractedas it iswoundbackwhilesometailstockshavea throughholeandneeda tapwithabar to remove thetool Handwheel depth graduations for drill drilling to a

particularholedepthareveryusefulbutarenotoftenincludedon the cheaper lathes although industrial lathes usually havegraduatedtailstockhandwheelsThebettermakesoflathehavea lever clamping tailstock arrangement while the cheaperlathesoftenhaveaclampingspanneroranAllenscrewclamp

Allguardsshouldbefittedinplacebeforeoperatingthelathe

MACHINEGUARDS

Thedrivemotorcountershaft(iffitted)andpulleybeltsshouldallbeproperlyguarded It isveryeasy togetcaughtup inanunguardedmachineandtheconsequencescanbequitenastyThis has never happened to me but I have seen someonecaught up in a machine and it was not very nice I dorecommend that you make sure your machine guards arecorrectlyfitted

OTHERDESIRABLEFEATURES

Digitalreadoutsareusefulonalatheastheycanshowyouhowmuch to move the handwheels and how much material hasbeentakenoffTheyarequiteexpensivebutyoucan fit themyourself if youare carefulUnfortunatelymost of the cheaperversionsdislikesolubleoilorothercoolantifyougetitintothereadouthead

Adigitalreadoutsuitableformountingonalathe

Youwillneedtwoslidesoneforeachaxis

A soluble pump for cutting fluid is useful and often comesfittedasstandardonthelargerlathesHoweveratinofcuttingoilandabrushwillbegoodenoughformostworkandthatmaysuityoufine

Solubleoilpumpsandreservoirsarereadilyobtainable

Formostjobsyoucangetawaywithsomecuttingoilabowlandabrush

TheMyfordlsquoNortonrsquostylequickchangescrewcuttinggearbox

A Norton quickchange screwcutting gearbox saves time asyou donrsquot have to set up changewheel trains A gearboxhowever considerably increases the price of the averagesecondhand lathe A Myford Norton gearbox has twenty-fourpitchesandiscontrolledbytwoleversReversingtwogears inthe Myford changewheel train gives the gearbox twenty-fourfine feeds insteadof the twenty-fourscrewcuttingpitchesThegearboxhasa setofgearsarrangedasaconeBysliding thelever along and dropping themaster gear onto the cone youcanchangethegearboxratioandsothepitch

TheconegearsinsideatypicalNortonscrewcuttinggearbox(notanoriginalMyfordone)

SeveraldesignshavebeenpublishedtomakeyourownNortontypescrewcuttinggearboxThisoneisavailablefromHemingwayKits

SPINDLESPEEDS

Thespeed rangeneededona lathedependson thework it is

requiredtodoAgoodrangeofspindlespeedsisdesirablewithnoobviousgapsWithelectroniccontrolthisshouldnotbetoomuchofaproblemIdeally a back-geared lathe would be best but this means

either a good secondhand machine such as a Myford or aBoxford or alternatively one of the larger Asian-made latheswithanall-gearedheadstock

Thisbackgeararrangementisswitchedinandoutbyturningthetoggleonthepulleyandliftingaleveratthefrontofthelathe

Backgearnormallyconsistsoffourgearstwolargeonesandtwosmalloneswhichcanbeswitched inorout toreducethespeedofthelathebyaratioofusuallyabout51dependingonthe maker to enable you to turn large diameter workpiecesThis reduction is also essential on a screwcutting lathe asotherwisethemandrelwillbegoingtoofastwhilescrewcuttingandyouwonrsquotbeable tostop in the rightplaceat theendofthethreadIf buying a back-geared lathe check that both gearwheels

havealltheirteethItisamajorjobtostripdownalatheandfitnewgearwheelsassumingtheyareevenavailableassparesCheckthelatheinallgearrangeswiththelatherunningIfa

back-geared lathe or an all-geared head is noisy it could

indicatewearitwillalsobeanuisanceinyourworkshopasnoonewants to hear a noisymachine runningNoise could be amajorproblemespeciallyifyouhaveneighboursnearbyGearedheadsusuallyhaveawiderangeofspeedsthelarger

industrial lathescangoup tospeedsof2000rpmandsmallerversionsareoftenhigher

Anall-gearedheadonamodernindustrialsizelathe

On the more usual amateursrsquo lathe there is often acountershaft usually tensioned by a lever which tightens upthebeltreadyforuseThemiddlespeedofthecountershaft isusually chosen to be about one quarter of the motor speedMost small lathes have three speeds and the back geararrangement adds another three speeds giving six in all TheMyfordSuper7rangeoflatheshavefourspeedsandbackgearmaking eight speeds but there is also a double pulley on themotor countershaft section making sixteen speeds in allalthoughtheverylowestback-gearedspeedswillrarelyifeverbeusedSomeoftheolderColchesterChipmasterlatheshavewhatis

knownasaKoppVariatordriveThis isavariable speeddrivecontrolledbyadialandthesystemworkswellbuttheVariator

isveryhardtoreplaceifthedrivefails

ThissmallCowellslatheiscapableofdecentworkandatthetimeofwritingisprobablytheonlylathestillbeingmadeinBritain

MOUNTINGTHELATHE

There are three main options for mounting a lathe benchmounting portable or on a stand Ideally a makerrsquos standshouldbeusedformountingamediumto large latheandthestandisoftenanintegralpartof larger lathesAsmaller lathesuch as a Unimat or a Cowell can bemounted on a woodenchopping board or a similar small board These lathes can beputawayinacupboardafteruseThe alternative is a workbench but these are often made

from wood which can expand or contract depending on themoistureintheairWoodisnotagoodmaterialfromwhichtomakea stand for a larger latheas itwill attractmoisture andmayexpandshrinkordistortAmetalstandisabetteroptionWewilllookatinstallingthelatheinChapter2

AnArcEuroTradeC3screwcuttinglathemadebySiegThisisaverypopularentrylevellatheandmanyaccessoriesareavailable

Amedium-sizedscrewcuttinglathesuitableforgardenshedworkshops

SHOULDIBUYNEWORSECONDHAND

Beginnerssettingupaworkshopoftenaskifitisbettertobuyanew lathe or secondhand The preceding pages should have

given some guidance but there are more points to be takenintoconsideration

Alargerindustriallathewithafoot-operatedemergencycut-offswitchandbrake

BuyingNew

Thelistoflathesuppliersincludedatthebackofthisbookwereall in business at the time of writing Most will be willing todemonstratetheirrangeofmachinesattheirpremisesorwhileattendingmodelengineeringexhibitionsPaycloseattentiontomechanical noise the general paint finish and the workingslideway surfaceswhich should begroundDoes themachinehave sharpor roughedges (Handwheelsareespeciallypronetosharpedges)The main thing to consider though is the attitude of the

supplier Were they willing to talk to you and answer yourquestionseitheratanexhibitionoroverthephoneHowlongdo they take toanswer thephonewhenyou ring their servicedepartment Do they know the answer to a simple questionstraightawayordotheyhavetogetbacktoyouIsthemanual

written in English or Chinglish (translated awkwardly fromMandarinorCantonese)There are several suppliers of new lathes inmost countries

aroundtheworldbutthemajorityoflathesaremadeintheFarEastOftensupplierArsquosmachinescomefromthesamefactoryassupplierBrsquostheyarejustpaintedadifferentcolourandhavedifferentnamesandlabelsfittedAftersales service can vary greatly Usually companies that

havebeeninbusinesslongerwillofferbetteraftersalesservicebutotherpeoplersquosexperiencescanbefoundonInternetforumsoratlocalmodelengineeringclubsUsually theAsian lathesare reasonablywellmadebut they

often suffer from having plastic gears instead of metal onesOneortwocompaniessupplymetalgearsasstandardso it isworthaskingiftheirmachineshavemetalorplasticdrivegearsSome companies also offer after-market replacement metalgears

BuyingSecondhand

There aremany good quality secondhandmachines availablebut there is also a lot of worn-out rubbish If possible take aknowledgeable friend with you when purchasing a lathe Becareful when buying at online auctions such as eBay MostsellersaregenuinebutsomearenotNeverpartwiththecashuntil youhavechecked the latheover IhaveboughtoneBaywithoutproblemsbut Iamcarefulwhat IbuyandwhofromAsmall latheforacoupleofhundredpoundsisunlikelytobreakthe bank if it is a bit of a dog but a lathe that costs severalhundredpounds is adifferentmatter ThegreenMyfordML7RpicturedthroughoutthisbookwaspurchasedfromeBayItwasbrand new the motor had never been fitted and it was abargainwhencomparedwiththeretailpriceIdidpaycashoncollectionbutIwouldhavewalkedawayif ithadnotmatchedthedescriptioninanywayWhether purchasing new or secondhand check what

accessoriescomeaspartofthepackageandwhatwillneedto

bepurchasedseparatelyEssentialtoolingcanoftendoublethecost of a newmachine if it is not included in the price whilededicatedtoolingmaynotevenbeavailable forasecondhandbargainlathe

Youshouldnowhaveanideaofthesizeoflatheyouneedthefunctionofthedifferentpartsofthelatheandwhetheryouarebuying new or secondhand In Chapter 2 we will look atinstallingthelatheandsafetyintheworkshop

2InstallingtheLatheandUsingItSafely

If you are buying a new lathe completewith delivery to yourworkshopyoucangostraighttothesectiononsettingthelatheupIfyouarecollectingthelatheyourselfhoweveryoushouldpayattentiontoafewwordsonmovingit

Ifyouhaveroomtomanoeuvreanenginehoistcanbeusedtomovemachineryaroundsafely

MOVINGTHELATHE

MOVINGTHELATHE

When going to collect your lathemake sure someonewill betheretohelpyouloaditortakesomeonewithyouUnlessitisaminiaturelatheitwillbetooheavyforonepersontoliftHelpisalsoneededwhenyougetthelathehomeLiftingthelatheoutofacarcanbeharder than lifting it in It isadvisable tohavethreepeoplewhenunloading twoat theheavyheadstockendandoneliftingthelightertailstockendYoucanrentorbuyanenginehoist fora reasonablepriceand this canmakemovingthemachineeasierIf the machine is a substantial industrial type it would be

besttohireatransportcompanythatspecializes inmachineryremovals Professional machinery removers will usually haveproperlyequippedtransporttomoveheavymachinesThiswillprobablyworkoutcheaperthanattemptingtodoityourselfbutmake sure they have insurance in place in case they damagethelatheoryourpropertyYoushouldalsoensuretheyknowithas to beput in place as required in theworkshop youdonrsquotwanthalfatonofmachinerydumpedonyourdrivewithnowayofmovingitintopositionLathesareusuallytopheavywhenbeingmovedandcantip

overifyouarenotcarefulTheMyfordML7seriesforexampleoftenhasthemotorandcountershaftboltedtothebackofthelathe bed and this type of lathewill tend to tip backwards Asimple solution is to bolt two lengths of wood about 4 times 2in(100times50mm)tothelathefeetOneboltineachendwilldoifyou canrsquot drill holes in the correct position This will stop thelathe tipping backwards and also make it easier to lift IfpossibleyoushouldremovethetailstockThisisoftenaheavylumpofmetalbutitisusuallyveryeasytoslideitofftheendofthelathebedAnyotherlargeobjectsthatcanberemovedandreplacedlaterwillmakethelathelighterandeasiertomove

Twoplanksofwoodboltedtothelathefeetwilloftenturnanunmanageablemassofmetalintoaneasilyhandledmachine

Azerovoltsswitchisessentialequipmentonanymachinetool

Wearoldclotheswhenmovingyourlatheandhaveplentyofold rags to wipe off swarf and oil Lay down old blankets ordecoratorsrsquosheetsinsidethecarandasheetofthickcardboardMDForplywoodtohelpprotectthebootareawhenslidingthelatheintothecar

AsmallishlathecanoftenbefittedintoastandardhatchbackorestatecarYoumayfindhowever thatyouhavetodotwotrips one for the lathe and accessories and another for thecabinetthelathestandsonTosaveawastedjourneyIusuallytrytofitthelathecabinetinfirstIfIthenfindthatthecabinetdoesnrsquotfitIcanstillbringthelatheandtoolinghomeknowingthat Ihave tohireavan tocollect thecabinetbutalso that IhavenothadawastedjourneyIfyouhavetosplittheelectricsforexampletotakethelathe

offthecabinetdrawadiagramoftheelectricalconnectionssoyoucanrewirethelathewhenyougetithomeAdigitalcameraisalsoagoodmethodofrecordingthewiringconnectionsbutIwouldnotrelyonthecameraaloneIf the lathedoesnothaveazerovoltsswitch itwouldbea

good idea to fit one after you get the lathe home They areavailable quite cheaply andare easily fitted If in doubt aboutyourabilitytodoelectricalwiringconsultaqualifiedelectrician

Adjustablefeetareveryusefulforlevellingupthelathe

SETTINGUPTHELATHE

Somelathesusuallythelargerindustrialoneshaveanintegral

bedandcabinetThelathecanbesettotruewithjustshimmingunderthefeetorbyadjustingthefeetOther lathes may need to be mounted level and true to

ensureaccuracywhenturningSetthebenchstandas levelasyou can in both directions using a spirit level as a guide Anycheapspirit levelwilldoas longas it isaccurateYoucantesttheaccuracyofaspiritlevelbyturningitround180degreesifitisaccurateitshouldreadthesamebothwaysOnce the stand is reasonably level youcan level the lathe

ThisinvolvesjackingorshimmingupthelatheuntilitistrueinbothdirectionsIfusingawoodenbenchputmetalplatesunderthe feet tospread the loadShimoradjust the latheuntil it isreasonablylevel

Putthespiritlevelonthecabinetrsquoslongitudinalaxisandusetheadjustablefeettolevelthelathe

Insertalengthofbarinthechuckandputadialtestindicatoron top of the tailstock end of the bar Nip the headstock endmounting bolts down first and then tighten down the tailstockendboltsAdjustorshimthetailstockenduntilthereisnosignof movement on the test indicator Next 64repeat theprocedure with the dial test indicator on the front of the barAgainyouare looking fornomovementCheckbothdirectionsagainmakingsurethereisnomovementeitherhorizontallyorverticallywhenyoutightenthelathedownAdjustorshimuntil

there is no movement in either direction when the lathe isclampeddownAslongasthebedisnottwistedthelathebedshouldnowbetrue

1Insertapieceof⅛in(3mm)packingunderthespiritlevelatthetailstockendThiswillresultinarunonthedriptrayandalltheoldoilwillruntotheendofthelathemakingiteasiertocleanup

2Placethespiritlevelonthecabinetcrossaxisandusetheadjustablefeettolevelthelathe

3Putthespiritlevelonthelathecrossaxisattheheadstockendandlevelitasbestyoucan

4Putthespiritlevelonthelongitudinalaxisandlevelalongthelathe

5Testthetopofthebarthereshouldbenomovementwhenthelatheisclampeddown

6Testthefrontofthebaragainensuringthatthereisnomovementwhenthelatheisclampeddown

Alignthetailstockbyusingadialtestindicatorintheheadstock

AligningtheTailstock

NowweneedtosetthetailstockinlinewiththeheadstockDothisbyputting thedial test indicator into theheadstockchuckandtestthetailstockboreAdjustthetailstocktowardsthefrontortothebackofthebeduntilthetestindicatorreadstrueandtighten theclampscrewsA slightdifference inverticalheightwillnotbetheendoftheworlditjustmeansthereisprobablysomeweartothebaseofthetailstockcastingbutthereshouldbenovariationfromfronttobackinthehorizontalalignmentPutalongbarbetweenthecentresandtakealightcutalong

it using a fine power feed Run along the bar a couple moretimes at the same setting to remove any push offWhen youmeasure thebar it shouldmeasure the sameatbothends Ifthe bar is larger at the tailstock end you need to reduce theheightofthebedatthefrontofthetailstockslightlyIfsmalleratthetailstockendyouneedtoreducetheshimatthebackofthe tailstockend Itprobablywonrsquotneedmuchadjustmentasslightadjustmentstotheshimoradjustersatthetailstockendwillsoonbringitintoline

Usingatestbartocheckforparallelturning

LubricatingtheLathe

You should follow the manufacturerrsquos recommendations forlubrication Usually this is thin oil for the headstock oftenhydraulicoilandslidewayoil forthemovingpartsLubricationshouldbedoneregularlyIfthelatheisfittedwithasightfeedoileritshouldshowoilinitAdjustablesightfeedoilersasusedonMyfordandsimilarlathesshouldbeadjustedsothattheoildripswhen the lathe is running but does not dripmuchwhenthe lathe is stopped The slight vibration when the motor isrunningisusuallyenoughtocausetheoiltodripToomuchoilisbetterthannotenoughoilisfarcheaperthannewbearings

Atypicaldrip-feedlubricator

UseanoilgunonalltheoilnipplesYoucangetaroundthetendencyfortheoiltogoeverywhereexceptintothenipplebyputtingapieceofwritingpaperoverthenippleandthenusingthe oil gun as normal The paper will stop the oil squirtingeverywhereThemandrelbackgearalsoneedstobelubricatedWheninusethemainbackgearisrunningontheoutsideofthelathemandrelandneedstobelubricatedoftenoritwillgethotandwearChangewheels should be lubricated with oil not grease If

youusegreaseswarfwillsticktothechangewheelsandcauseunnecessarywearTo stopswarf running through themandrelanddroppingoutontothechangewheelsputawinebottlecorkor similar into the left-hand end of the mandrel This willeffectivelystopanyswarfgettingthroughtothechangewheelsOil the saddle and cross slide and also the nipples on the

tailstock Make sure oil is showing at the edge of the slidingsurfaces A squirt of oil on the cross slide and topslide feedscrew bearing is needed as well Check the manufacturerrsquosinstructions for lubricating the rest of the lathe Follow themotormakerrsquosrecommendationforlubricatingthemotorTrytoavoidusingWD40onthelatheWhileitisanexcellent

lubricantwaterdisplacerittendstodiscolourthelathebed

Useabitofpaperundertheoilguntostoptheoilsquirtingeverywhere

AvoidingtheRustFairy

Rust canplayhavocwith a lathe quickly turning thebedandother parts into a brownmess Various sizes of plastic coverssuitable forcovering lathesareoftensold foruseasbarbecuecoversinDIYstoresAplasticlathecoverwillhelptokeeprustatbaybutmoreneeds tobedoneAbagcontainingsilicagelplacedundertheplasticcoverforexamplewillabsorbexcessmoisturesilicagelcanbeboughtverycheaplyoneBay

SilicageliseasilyobtainablefromeBay

Alternatively you can buy a vapour phase inhibitor forprotecting the lathe The vapour phase inhibitor chemical issuppliedonafeltpadinsideaplasticpotThechemicalformsaprotectivelayeroneverysurfaceBecauseitisavapouritwillfind its way into every cranny and is also used for protectingtools and accessories in tool cabinets and drawers It usuallylasts for twelvemonths ifenclosedby theplasticcoverSomemachinetooldealersareabletosellsuppliesofthisproductinsmall ready to use containers rather than in industrialquantitiesAlwayscleanthelathedownafteruseswarfwillsoonrustif

leftonalatheasitwillprobablybecleanfromturningandwillnotbeprotectedbyoilTheuseofanovencookingtrayunderthe lathe bedmakes it easy to remove swarf at the end of aturning session The tray also helps to retrieve a parted offcomponentora lost screw froma tipped turning toolAnotheralternativeistocoverthelathechiptraywithnewspaperwhenyouhave finished turning remove thenewspaper screw it upandthrowitawayWhenfittingachuckorfaceplatetothelathemakesureyou

cleanthemandrelthreadtheregisterandthefaceYoushouldalso clean the mating threads the bore and the face on thechuckorfaceplateYoucancleanthethreadandboreeasilybyusing two toothbrushes bolted back to back with spacers inbetween Make sure the Morse tapers in the headstock andtailstock are cleanbefore fitting aMorse taper accessory TheMorse taper to be fitted should be free from scratches burrsandbruisesIt is good idea tomake a chuck board for usewhen fitting

chucks to a lathe or removing them This is a piece of wood(plywood will do) that sits on the lathe bed while you arescrewingthechuckonandoffThechuckboardwillprotectthelathe ifyoudrop thechuck It canalsobeused toprotect thelathebedwhenyouarehacksawingorfilinginthelatheIf you keep your lathe clean and lubricate it regularly it

shouldlastalifetime

AlargetraywillcatchmuchoftheswarfandtheholeslettheoildrainawayUsenewspapertosoakuptheexcessoil

SAFETYINTHEWORKSHOP

RememberyouareresponsibleforyourownsafetySafetyisamajorconcernintheworkshopTherearecertain

thingsyoushoulddoandobviouslythingsyoushouldnotByitsverynatureaworkshopcanbeadangerousplaceallwecandoismakeitassafeaspossiblewhilestillallowingustoworkinit

WorkingAlone

Mostofyoureadingthisbookwillprobablybeworkingaloneinasmallworkshopgarageorgardenshed IfyougethurtyoumaypossiblybeonyourownAsapriorityIsuggestyoutakeamobilephoneintotheworkshopandkeepitinyourpocketTheability to contact your family a friend or the emergencyservicesquicklycouldsaveyour lifeKeepthephoneswitchedoff while in the workshop however as it is an unnecessarydistraction

FirstAid

FirstAid

AFirstAidboxwithcontentsisanecessityandshouldincludeaneye-bathandeyewashYoushouldparticularlylearnhowtostopbloodflowingThereareplentyofwebsitesthatwilltellyouhowtodothisCheckthemoutnowbeforeyougobackintotheworkshop

ElectricalSafety

Checkforearthcontinuitywhilethemachineisunpluggedwithavoltohmmeterfromtheearthpinonthethreepinplugtothemetalpartofthelathe(somepaintmayhavetoberemovedforareadingtotakeplace)Youshouldgetareadingofzeroohmsorabeep if themeterhasacontinuity rangeYoushouldalsobe sure that the electrical sockets on the wall are correctlyearthedIfindoubtconsultacompetentelectricianLightingandelectricheatingshouldbeonaseparatecircuit

tothemachinessoyouwillstillhavelightifthemachinestripoutPlugasmalllightintothemachinecircuitsoyouhavesomelight if the lighting circuit trips out When I go on holiday Ialwaysturnoffthefusetripsforthelightinginordertomakeitmore difficult for intruders to move about quickly Leave thehouse alarm and smoke detectors on (The house alarmmayactivateeighthoursafter theelectricity is turnedoffwhenthebatteryexpires)

Adigitalmultimeterisveryusefulinthehomeworkshop

BeAware

Bementally alert while using the lathe Avoid operations thatmightputyourhandsatriskofenteringthemovingpartsofthelathe Do not operate any lathe while under the influence ofdrugs alcohol or prescription medication that may causedrowsinessorotherwiseaffectyourability to control the lathesafelyDonotattempttoworkonalatheandtalkatthesametimeIfyouhavetotalktosomeoneswitchoffthelathebeforedoingso

KeepItClean

TheareaaroundalatheshouldbekeptfreeofobstructionsThefloorshouldbecleananddrywithanyoilorotherspillscleanedup immediately The lathe should be kept clean and tidyMachinedangerareasshouldbemarkedontheworkshopfloorand observed Workbenches placed near a lathe should be

strongandequippedwithanon-slipsafetysurfacetostoptoolsor other items rolling onto the floor a rubber car mat willsufficeA rubberdoormat on the floorwill allow swarf todropthrough in order to save you getting swarf embedded in thesolesofyourshoes

Asuitablefloormatwillallowswarftodropthroughandhelpkeepyourfeetwarminwinter

LearntoUsetheLathe

Donotuseany lathebeforeyouare familiarwith thecontrolsandareawareofthedifferentwaysofstoppingitThismaybea clutch an onoff switch a No Volts release switch or anemergency stop button I strongly advise fitting a No VoltsreleaseswitchifyourlathedoesnothaveoneAswellasbeingusefulforstoppingthelatheinanemergencyitwillpreventthelathefromstartingupbyitselfafterapowercutIfyouarenotcomfortableworkingwith electrical equipment get a qualifiedelectriciantofittheswitchforyou

StaywiththeLathe

Nevereverwalkawayevenforamomentwhilethelatheyouare using is switched on Switch it off if you are leaving itunattended and only leave the lathe after it has come to a

completestopNeverleavealatheinanunsafeconditionMakesure that you have not left the chuck key in the chuck Thechancesarethatifyouarehalfwaythroughsettingupthelathewhen you return you will forget what you have or have notdoneIfindoubtleaveabignoticeremindingyourselftocheckthatthelatheissafebeforecontinuing

Donotleavethechuckkeyinthechuck

SwitchOffwhenAdjustingtheLathe

Shut off the power supply to the motor before starting anyoperationsrequiringaccesstothelathesuchaschangingtoolsmeasuring work mounting or removing accessories changingspeed and setting up change gears The lathemust be safelystopped Just zeroing a variable-speed drive is not safelystoppingitusethezerovoltsswitchtoswitchthepoweroffaswell

CheckbeforeStartingtheLathe

AlwaysrotateyourworkpiecebyhandtomakesureitclearsthetoolrestsaddleandbedDoublechecktomakesureyourworkis securely clamped in the chuck or between centres beforestartingthelatheBecertainthattheworkpieceturnsfreelyand

isfirmlymountedThespeedofthelathemustbecheckedbeforeturningiton

When turning irregular shapes start the lathe on a low speedandincreasethespeedbyapulleystepeachtimeIfthelatheisbouncingabout lowerthespeedandorbalancethework Ifthe work vibrates stop the lathe and check the reason ThechancesarethatyouarerunningthelathetoofastMeasuringequipment toolingandworkpiecesshouldnotbe

leftona latheastheycanvibrateoff intomovingcomponentsand be thrown around the room Check for loose items on alathebeforeuse

UsetheLatheGuards

NewlatheswillbefittedwithguardsoverthemotorshaftdrivebeltandspindlepulleysTheseguardsshouldalwaysbeinplacebefore using the lathe Any other moving parts should beguardedtopreventanythingfallingontothemovingpartsAlthoughguardsareoften removedbymachinistsprovided

they are constructed from clearmaterials and open and closeeasily theyaddsafetywithout interferingwith theworkbeingdone Guards will at the same time deflect swarf and anycoolantthatisbeingusedGuardsfittedtothelatheshouldnotbe removed while it is in use They should be made fromsuitablematerialandnothavesharpedgesTheyshouldnotberemovedforadjustmentandlubricationofthelatheunlessthisis unavoidable Lathemanufacturers donrsquot usually supply chipguards soaddingoneshouldbeconsideredChipguardswithmagnetic bases are available although they can attract steelswarftothemagnetPutthebaseintoaplasticbagtoaidswarfremoval

UseEyeProtection

Lathes can throw sharp metal chips considerable distancesespecially at high cutting speeds Apart from deep cuts thechipsmay leave the tool red hot cause skin burns and even

burnholes in clothing Youmust use safety goggles or propersafetyspectacleswhileintheworkshopAlwayswearindustrialqualitysafetyglassesfittedwithsideshieldsSpectacleswithoutsafety lenses are not adequate eye protection When theglasses get dirty do not wipe them off as they will becomescratchedWashthemoffunderthetapinstead

TakeCarewhenRemovingSwarf

Do not attempt to remove chips or turnings with your handsAlwaysswitchoff the lathefirstandeitherpull theswarfawaywithalargemetalhookorliftitoffusingapairofglovesIftheswarf is tangled around the lathe untangle it with a pair ofpliersandnotaglovedhandasitwillcutstraightthroughtheglovesandintoyourhandUseadustpanandbrushtoremovesmall chips and swarf from the swarf tray ndash never use yourhandsWhenswarfbecomesstringyandbuildsuponthetoolortoolpostturnoffthelathebeforeremovingit

AvoidLooseClothing

IfyouarenotwearingoverallswearshortsleevedshirtsorrolllongshirtsleevesabovetheelbowsLoosesleevescancatchonrotatingworkandquicklypullyourhandorarmintothe latheObviously though keep your arms protected if hot swarf isflyingaroundSwarf can get inside protective clothing especially collars

(useaclothespegtokeepyourcollartight)pocketsandshoesTostopthesleevesofanoverallcatchingsewelastic intothecuffsorwrapacoupleofthickelasticbandsaroundthecuffstostopthesleevesgettingcaughtupUnder no circumstances wear a necktie when operating a

latheProtectiveglovesshouldneverbewornwhileoperatingalathe Protective gloves may be worn when swarf is beingremovedbuttheymustberemovedbeforeswitchingthelathebackon

UseSturdyFootwear

WearsteeltoecapsafetybootstheyarenotexpensiveandwillhelptoprotectyourfeetfrominjuryifyoudropaheavyobjectonthemThelsquotrainerrsquoversionisparticularlycomfortableDonotallow stringy swarf to fall on the floor as youwill get cuts onyouranklesandmayeventripoverit

AvoidJewellery

Do not wear wristwatches rings or jewellery when in theworkshop as it could catch on a rotating part of the lathe orworkpieceThisalsoapplieswhenmovingalatheintooroutoftheworkshopsincetheycouldcatchona falling lathe IfyourotherhalfcomplainsthatyouhavetakenoffyourweddingringexplainthatyouwouldnrsquotbeabletowearitagainifyourfingerismissingduetoanaccidentLonghairshouldbetiedbackasyoucouldbepulledintothelatheifitgetscaughtintherotatingwork

LiftingintheWorkshop

Back injuries can be caused by incorrect lifting practices It isimportant to bend your legs when lifting rather than bendingyour back A hoist or engine lift should be used to lift heavyitems A stool in theworkshopwill take the pressure off yourlegs and will provide a welcome break after you have beenstoodatthelatheforawhile

Self-ignitingMaterials

If you machine titanium or magnesium which can ignite andburn vigorously keep the accumulation of turnings to aminimum If thematerialdoescatch firedonrsquotusewaterorawater-based coolant as an extinguisher since it will makematters much worse Before starting to machine titanium ormagnesiumfillalargebucketwithdrysandcoveritandkeep

it by the lathe The sand will smother the flames veryeffectivelyYoucouldalsobuyoneofthespecialfireretardantsusedinindustryBeware also of grinding aluminium on the bench grinder

Aluminium and steel filings are the ingredients of Thermite apowerful explosive that can also burn If you grind aluminiumandthenchangeovertogrindingsteeltheredhotsparksareliable to set the steelaluminium mix on fire This is a verydangerous combination ofmaterials and should be avoided atallcosts

SafetywithBarStock

Bar stock should be contained within the headstock and notallowed to protrude from the rear of themandrel I once sawsomeone switchona lathewhenabrassbarwas stickingoutfrom the back of the headstock by about two feet With thelathe running at 2000rpm the bar whichwas aboutfrac34in (19mm) in diameter was bent at right angles and caused theheavy lathe which weighed 1280kg to jump about Luckilysomeone managed to switch the lathe off before any majordamageoccurredItwasnottheoperatorhehadrunwellawayandwasnowheretobeseen

SomeFinalWordsonSafety

Wherever possible the machine height should be adjusted tosuittheuserWearestillusingfifty-year-oldmachinesbutfiftyyearsagothenationwasshorterTheworkplaceshouldbeprovidedwithuniformlightingthat

gives an adequate level of illumination Individual machinelightsarebestThe lathemust be set to operate at the speeds and feeds

recommended for thespecificmetalbeingturned If themetalrotatestooslowlyortooquicklyorthefeed istooslowortoofastaccidentsarelikelytooccurThe area directly in front of and behind the workpiece is

known as the lsquofiring zonersquo or the lsquored zonersquo This is where apiece of work is likely to go as it leaves the lathe Make it ahabit to keep clear of this zone when you turn the lathe onLearnwhere theNoVolts switch is as youmightneed to turnthelatheoffquicklyByfollowingalltheaboveadviceyoushouldnowbeableto

worksafelyfullyawareofanysafetyproblemsthatmightariseAtthispointyounowknowhowtoinstallthelathelookafter

itclean itandmaintain it InChapter3wewill lookatcuttingtoolsandexaminehowtoselectcuttingspeedsandfeeds

Thisbarisstickingouttoofarfromthebackofthelathe

3CuttingToolPrinciplesFeedsandSpeeds

The first part of this chapter will look at the materials fromwhichcuttingtoolsaremadeaswellastheirbasicshapeandgeometryWewill thenconsider selectingsuitablespeedsandfeeds

MAINTYPESOFTURNINGTOOLS

There are three main types of turning tool used in modernworkshops HSS (high speed steel) tools carbide brazed-ontoolsandinsertedtiptoolsAllhavetheirusesintheworkshopandformost jobsthere isnopreferenceforonetypeovertheothersTherearealsocarbonsteeltoolbitsalthoughinpracticetheyarejustaboutobsoleteCarbonsteeltoolscanbemadeinthe homeworkshop but apart frombeing used tomake formtools(seeChapter11)thereaderisunlikelytousethismaterialfortools

Ageneral-purposeHSSturningtoolsuitableformildsteel

HSSTOOLS

HSStoolscanbepurchasedsinglyorinsetsalreadygroundtothecorrectshapeIt ischeaperhowevertopurchasethemassquare tool blanks in various sizes ready for you to grind toshapeThecompleteready-groundsetswillprobablycomewithseveralshapesincludedthatyouwillneveruseIfyoucanbuyafewready-groundtoolscheaplytheywillbeofuseasguidestoseehowtosharpenyourownHSStoolblanksHSS form tools from industry are often available second-

handTheseareespeciallygroundtomachineacomplex formall in one go You can often find some that are ground to asuitable shape to form the end of a threaded componentincludingtheundercut

HSSformturningtools

Brazed-onCarbideTools

Brazed-on carbide-tipped tools are quite useful especially forfacing and boring cast iron but they really need a diamond-facedgrindingwheeltokeepthemsharpCarbidetipsandtoolscomeinvarioussizesandhardnesstosuitindividualmaterialscarbidetoolsforsteelwilloftenbepaintedbluethoseforcastiron are painted red and those for stainless steel are paintedyellowThecolourindicatesthesuitabilityofthetoolforcertainmaterials

Brazed-oncarbide-tippedtoolscomeinvariousgradesshapesandsizes

InsertedTipTools

InsertedcarbidetiptoolsareveryusefulbuttheyarenotcheapThe tipsarenotusually sharpenedafterwearingout you justthrow the tip away and fit a new one Most modern carbide

inserts however do have more than one cutting facesometimestheyhavetwoandoccasionallyfourormorecuttingedgesareavailableYoucanevengetformturningtoolswheretheinsertisroundandcanberotatedafull360degrees

Theleft-handtoolisblueindicatingitisformildsteelwhiletheright-handtoolisredindicatingitisforturningcastiron

Some diamond-shaped tips can be used in different toolholders two edges are used in one tool holder and the othertwoedgesareusedinanothertoolholdersoyougettwicethelifepertipInserted tip tools are available for internal and external

screwcuttingwherethetipsareheldat thecorrecthelixangleofthethreadinthetoolholderThedrawbackisthecostofthetipsandeachsizeofthreadusuallyneedsitsownsizeoftip

Aninsertedtipcarbideturningtool

Carbidegroovingtools

InsertedtipgroovingtoolsareidealformachininggroovesforOrings and circlips Theyare available inmany standardwidthsandcanoftenbeusedasparting-offtoolsforsmallerdiametersOneof themostusefulgrooving tools forsmallersizegroovesandpartingoffistheMiniThinsystemassoldbyMSCIndustrialSupplyCo

TheMiniThintoolholderisidealforgroovingandalsoforpartingoffsmalldiametersTheshankissostrongcomparedwiththecutbeingtakenthatusinganoverhangasshownisquite

safe

Coatingstoreducetoolwear

Tipsarealsoavailablewith various coatings that improve toollifeThemostcommoncoatingistitaniumnitride(TiN)whichisgold in colour Other coatings that offer slightly better wearresistancearetitaniumcarbonnitride(TiCN)whichisbluegreyincolourandtitaniumaluminiumnitride(TiAlN)whichisvioletbronzeReady-groundHSScuttingtoolssuchasdrillstapsandreamers are also available with these coatings but once yousharpenthecutterthecoatingisgoneTipped toolsneedadeeper cut ahigher feedandahigher

speed than HSS tools Thismeans that the lathe needs to bestrongrigidandhaveamplepowertodrivethe lathemandrelwhen taking a heavy cut this rules out using tipped tools onlathessmallerthanabout2in(50mm)centreheightSmaller tools are made to fit the Unimat and similar small

lathesbutthesemachinesjustdonrsquothavethepowerneededtodrivethemAtbesttakingacutwillstopthelatheatworstthetoolwillchip

Insertedtiptypes

Inserted tip tools come in many shapes and sizes Some tipshapes and sizes are made to an international standard andothers are to the makerrsquos own standards Wherever possibleuse ISOstandardtoolsas thetipswillbe interchangeablewiththosefromothermanufacturersandwillprobablybecheaperaswell The ANSI system commonly used in the USA is notcompatiblewiththeISOsystemusedintherestoftheworldIfyour lathe ispowerfulenoughyoucantakeadvantageof

insertedtippartingoffbladesThesearemounted inaspecialtoolblockandthebladecanbeslidinoroutdependingonthediameteryouarepartingoffThebladecarriesan inserted tipspecially designed for parting off There are three types of tipavailablesquare-endedtipstipsthatareangledtotheleftand

tips that are angled to the right Square tips are used forgeneral parting off tips angled to the left are usedwhen youdonrsquotwanttoleaveapiponthebackendoftheworkandtipsangledtotherightareusedwhenyouwantacleanfaceonthefrontoftheworkThe parting off blade is oftenmounted upside down at the

backofthe lathecrossslideTheactionofpartingofftendstolift the whole cross slide slightly and forces the cross slidetightly into thematching dovetail whichmakes itmuchmorerigidIfthepartingofftooldigsinwhileinthebacktoolpostthetool tends to lift and push away from the work whereas in afronttoolpostthetooltendstodiginandpullintothework

Simplifieddiagramofpartingofftoolangles(A)straightpartingtool(B)angledtotheleft(C)angledtotheright

POWERREQUIREMENTS

Whenturningmildsteelorstainlesssteelwithanycarbidetoolthe machine horse power required is considerably more thanthat required forordinaryHSStoolsThe twomain reasons forthisarethatcarbidetoolsoftenhaveanegativerakeangleonthecuttingedgeasthistypeofedgelastsmuchlongerthanapositiveangle especially for intermittent cuts andbecause in

industrial use carbide tips are called on to remove largerquantitiesofmetalathigherspeedsandfeedsFor guidance on using tipped tools in the small workshop

wheretimeisnotasimportantasinanindustrialenvironmentIwould recommendusing twice the speedused fornormalHSStools and a fine feed of about 0002in (005mm) per rev as astarting point This can be adjusted up or downdepending ontheresultsThemaindifferencebetweenHSStoolsandcarbidetippedtools(eitherbrazed-onorinsertedtip)isthehorsepowerrequirementofthemachineinuse

Thispartingofftoolismountedatthebackofthelatheinaspecialbacktoolholder

SELECTINGTHECORRECTSPEEDSFORDIFFERENTMATERIALS

Overmanyyears through trialanderror cuttingspeedshavebeendeterminedthatgiveanoptimumtoollifebalancedwithadecent surface finish These speeds are normally quoted inlsquosurfacespeedinfeetperminutersquoSpeeds and feeds used on industrial machines where the

primary tools will have inserted tips will be a lot higher than

thoseusedinthesmallworkshopwhereHSStoolsarethenormThe accompanying table gives an idea of the speeds that

shouldbeused forvariouscommon typesofmaterial likely tobefoundintheworkshopThespeedslistedshouldbesuitableforbothturninganddrillinginthelatheForreaminguseabout25percentoftherecommendedspeedsThe table is a guide only and it is likely that the machine

speedsavailablewillnotbeexactlythoserequiredandyoumayhavetoresorttolsquonearenoughisgoodenoughrsquoSetthelathetothe nearest speed lower than indicated in the table for thediameterandmaterialbeingcutThiswillbefineforHSStoolsDouble the recommended HSS speed for carbide tools For

parting off use about 30 per cent of the recommended HSSspeed For form tools use about 50 per cent of therecommended speed for the initial cuts and then engage thecorresponding back gear (just switch to back gear leaving thebelts on the same pulley) and gently tap the handle until itreachesthefinishedsizeandallowittofinishthecutbyitselfYou may have to adjust the speed down if you get a lot ofchatter

Forturningcastironuseacarbide-tippedtoolrunningattheHSSspeedtoremovetheskinYoucanthenfinishtheturningwithaHSSsteeltoolifyouwishPlease remember if doing any work that might be

unbalancedstartoffslowlyandincreasethespeedabeltstepatatime

THEACTIONOFCUTTINGTOOLS

Basicallya lathe tool isawedge that is forced into theendofthe rotating bar to remove metal As long as the tool is fedforwardwhilethelatheisrotatingmaterialwillberemovedA typical right-hand turning tool has a cutting angle of 90

degreeslessthesideclearancelessthesiderakeThecuttingangle for this example is 90ndash10ndash10= 70 degrees This is theangle that is wedged into the work to remove the materialSoftermaterialswillhaveasmallercuttinganglewhilehardermaterials will have a larger cutting angle Tool angles varydependingonthetypeofmetalbeingturnedToolsforturningsofter metals usually have higher rake angles than thosedesigned for harder metals since a turning tool will normallyholditsedgeforlongerinsoftermaterialsBrassalthoughsoftusuallyhasnotoprakeonthetoolatallOther angles to be aware of are the top rake and the side

rake

CUTTINGTOOLSHAPES

The followingaresomeof thedifferent shapes thatyoumightfindusefulforgeneralturningandmetalremoval

Right-handknifeturningtoolAllrakeanglesare10degrees

Right-hand knife tool This is used for general turning andfacingofbarstockDependingontheworkyouaredoingyoumayfindaleft-handversionofthistooluseful

Typicalroughingtool

Right-handroughingtoolIthasaleadingangleandasmallradius on the tip of the tool This tool is used for fast metalremovalwherefinishisnottooimportantAgainyoumayfindaleft-handversionusefulAroughingtoolcuttingatanangletoabarwillremoveachip

widerandthinnerthanatoolcuttingat90degreestothebarThis improves tool life although you will have to square theturningupwithastandardknifetool

Typicaldouble-sidedroughingtool

Double-sided roughing tool It can turn towards the left orright It canalsobeusedasaplunge tool to removematerialfroma groove orwhere the component needs to be lsquowaistedrsquodown

Simplepartingofftool

Simple parting off tool This is suitable formostmaterialsYouwillprobablyneedalargeoneforpartingofflargediameterbarsaswellasasmalloneforpartingoffsmallcomponents

Internal(top)andexternal(bottom)screwcuttingtools

ScrewcuttingtoolThisisusedforcuttingscrewthreadsTheanglewilldependonthethreadyouarecutting60degreesformetric55degreesforWhitworthandBSFetc

Shallowboringtoolcapableoffacingacrossthebottomofahole

Boring and facing tool This toolrsquos unusual shape will befound very useful when recessing a large bore It will plungestraight intoasmalldrilledholeandwillalso face rightacrossthebottomoftherecess

Double-endedchamfertoolchamferingadiameter

Double-ended chamfering tool It has 45 degree angles atbothendssoitcanbeusedtochamferexternaldiametersandinternalbores

Double-endedchamfertoolchamferingabore

Othershapescanbeusefulbutthetoolsshownhereshouldbesufficienttogetyougoing

BORINGTOOLS

Boring tools are used to clean up a previously drilled holepossiblytomakeitruntruebutmorelikelytoensuretheholeistothecorrectsizeTheyarenormallylongerthanordinarytoolsandtendtostickoutfurtherfromthetoolholderHSStoolsaresuitableformostusesCarbideinsertedtipboringbarsarealsoreadilyavailableandarethebestbetforturningcastironinthesmallworkshop

HSSboringbar

For really small holes down to2or3mm indiameter solidHSSandcarbideboringbarsarereadilyavailableAlthoughtheyarenotcheaptheywillbefoundveryusefulandquicktouseAnothermethodofboringahole is tousea longseriesslot

drillasaboringtoolInuseclamptheshankinthetoolholderwiththepointatcentreheightmakingsuretherestoftheslotdrillisclearofthesideoftheboreYoucanthenrunitthroughtheboreinasimilarmannertoastandardboringbar

Asmallcarbideboringbarinsertedintoamildsteelshank

PARTINGOFFTOOLS

PartingofftoolsprovideaquickwayofcuttingoffworkfromtheparentbarThereisrarelyanyneedtoworryaboutcuttingthecomponentofftothecorrectlengthtogetagoodfinishAslongasthecomponentislongerthanrequireditcanbeputbackintothe chuck or a collet and the parted off face can be faced tolengthorotherwiseworkedonThepartingofftoolcuttingfacecaneitherbesquareoritcan

beangledtotheleftorright(seepage43)Thesideofthepartingofftoolcouldevenberadiusedsothat

it forms a radius on the end of the next component orchamferedtoformalead-inedgeforthenexttool

CUTTINGLUBRICANTS

Tomake cutting tools cut easily and to prolong their life it issometimesbesttouseacuttinglubricantForsteelIpreferneatcuttingoilItlubricatesbutisnotidealforcoolingtheworkIn industry coolant is normally used This is oil that has an

additivetomakeitsolubleinwaterMostsolubleoilswilldobutthe synthetic ones tend to sting your hands if you have anyopen cuts I would not recommend using soluble oils on thehome workshop lathe as I think they tend to wash thelubricating oil off the slideways and can encourage rustHowever this ismypersonalpreferenceandmanypeopleusesolubleoilinthehomeworkshopwithoutanyproblemsOil is suitable for use when cutting steels mild steels

stainlesssteelsandhighcarbonsteelssuchassilversteelThebestlubricantwhencuttingaluminiumisparaffinItstops

thealuminiumfrombuildinguponthecuttingtoolBrassandcast ironarenormallycutdryWhenturningcast

ironona lathe if the latheisfittedwithasolubleoiltankthecastirondustwillhaveanaffinityforthesolubleoilIfthelatheisthenusedonaluminiumthefreecarboninthecast ironcancontaminatethealuminiumwithblackstreaks

Inormallyplacetheoilorparaffininasmalldish(actuallyacatordogfoodbowl)andapply itbyhandwithasmallbrushThisdoesallIneedThenextchapterlooksatgrindinglathetools

4SharpeningToolsandHoldingThemintheLathe

ThenexttaskistogrindasetofusefullathetoolsThe first thing you will need is an off-hand grinder The

grindercanbeadangerousmachineso itshouldbeusedwithcare Eye protection must be worn the guards should becorrectlyfittedandtheremustbeadequateilluminationIdonrsquotlike using a grinder in a small workshop as the grinding dustflies everywhere and canget onto themachine slideways andtools generally making the workshop dusty and dirty Ifpossible set up thegrinder in a separate areaaway from theworkshopIhavemygrindermountedonafoodchoppingboardso I can carry it outside to use This has the addedbenefit ofdaylight although you are dependent on the weather or youmightneedtouseitafterdark

Theguardofthisoff-handgrinderhasbeenwidenedtoacceptarecessedwheel

GRINDINGWHEELS

IthasalwaysbeenstatedthatyoushouldnevergrindatoolonthesideofthegrindingwheelSofollowingthistheorywewillbeusingarecessedwheelwhereitswidthismuchthickerthanthepartofthewheelusedtoclampthewheeltothegrinderIstruggledtofindarecessedwheelof6in(150mm)diameterandfinally found a 60 grit grinding wheel on a personal visit toAxminster Power Tools in Devon (I could find only an 80 gritwheel in theircatalogue)Thewheels I like touse forgrindingare A60K5V if I can get them and I prefer the white wheelsdesigned for the harder tool steels rather than the grey orbrown wheels which are more suitable for softer mild steelsThedesignationbreaksdown like thisA stands foraluminiumoxide 60 is the grit size K is the hardness (I J and K beingmediumhard)5 is thestructure(thespacebetweengrainsofgrit) and V is for vitrified the method of bonding the grainstogetherTheKandthe5canvaryabiteitherwayandthegrit

shouldbe4660or80with60beingpreferredThe80gritisabitfineandwillclogupquitequicklySo-called green grit wheels made from silicon carbide are

available for sharpening carbide tools They are usually softerthanaluminiumoxidewheelsinordertoallowthegrittobreakdownbeforethewheelbecomesglazedfromgrindingthemuchhardercarbide

Witharecessedwheelyoucancutontheouterfaceoftherecessedsideofthewheel

TestingtheWheel

The first thingyoushoulddowhenbuyingawheel is tomakesurethat it is ratedatasufficientlyhighspeedfor thegrinderon which it is to be used Off-hand grinders usually run ataround2900rpmsoyouwillneedawheelratedtoatleastthatspeed it is all the better if the grinding wheel is rated at ahigher speed than the grinder Care should be taken whenhandlinggrindingwheelsastheyarequitefragileifknockedordropped A grinding wheel should only be purchased from areputableengineeringsupplierSupportyourgrindingwheelona piece of wood and tap the wheel gently with a plasticscrewdriver handle or similar The wheel should lsquoringrsquo if itsoundsdullitshouldbebrokeninhalfandeitherthrownawayorusedontheworkbenchasasharpeningstoneNeverthrowawheelawaywithoutbreaking it into twoyouneverknowwho

mightgettheirhandsonit

Thistoolrestwasdesignedtosharpenplaneironsandchiselsbutitisfineforlathetools

Amoderndigitalanglegaugeisidealforsettingthetoolrest

MountingtheWheel

The wheelrsquos bore should be the same as the spindle of thegrindingwheelOften theborewillbe largerandyouwill then

need some plastic spacers to reduce it Spacers should bereadilyavailable fromyour localengineeringsupplierYoucanturn thespacers fromplastic if youcanrsquotbuyany ready-madeonesAt each side of the wheel you should fit a paper washer

thesearemadeofblottingpapertypematerialandwillprobablyhave been supplied already stuck on the wheel The grindershould have twometal flanges one to fit at each side of thewheel Both flanges should be the same diameter These willhold the wheel true and spread the tightening load on thewheelThegrinderwillhavetwodifferent threadsontheendsof its spindle The right-hand side of the grinder will have aright-hand thread and the left-hand side will have a left-handthreadThedifferentthreadsaretostoptheclampingnutsfromunscrewingwhenthegrinderisrunningTofitthewheelremovetheguardandundothenutRemove

the metal flange and then the wheel Make sure the flangesdonrsquothaveany remainsof theoldpaperwasheron themPutthenewwheelontothegrinderspindle(rememberthespacerthepaperwashersandtheflangesateitherside)andscrewthenuthand-tightFinallyholdthewheelgentlyandgivethenutapinchupwithaspannerYoudonrsquotneedtoover-tightenthenutjustsufficiently tostop thewheel fromcoming looseRefit theguard and spin thewheel by hand to ensure it is not rubbinganywhereNowwearealmost ready to switch thegrinder onBeforedoingsohoweverputonyoureyeprotectionandstandtoonesideofthegrindersoyouarenotinlinewiththewheelshould it burst Then switch the grinder on All should be fineandthewheelshouldberotatingsafely

TOOLREST

Theworkrestsuppliedwithanoff-handgrinderisusuallyjustabitofbentsheetmetalboltedonItisusablebutonlyjustI recently purchased a ready-made tool rest as a basis for

makinganimprovedgrindingrestThiswasoriginallydesigned

forsharpeningplanebladesandchiselsforwoodworkingbutitmakes an ideal rest for sharpening lathe tools It is made ofaluminiumandisfullyadjustableforangleThebestmethodofsetting the rest to the correct angle is to use a digital anglegauge These are now very cheap and are readily obtainableThepositionoftherestinrelationtothegrindingwheelcanbeadjusted on its sliding base Many designs for tool rests havebeenpublishedandyoucouldmakeoneofthoseinsteadifyouwishtosavemoneyThetoolclampassupplied isdesignedtoclampplane irons

andchiselssothisneedstobechangedLathetoolsneedtobepresented to the grinding wheel at the correct angles If youdonrsquot have a digital angle gauge this can be achieved usingsimpleguidesmadefromanglesheetmetalandsomescrewsIused gauge plate made from a high carbon steel with anaccurategroundfinishthatcanbehardenedandtemperedbutmild steel would be perfectly suitable if you donrsquot have anygaugeplateavailableYouwillfindaprotractorusefulyoucangetasteelonewith

an adjustable blade for a reasonable price The protractorwillbeusedtosetthetoolanglethatisgroundonthetools

Sheetmetalprotractorsareavailableverycheaply

LATHETOOLGEOMETRY

LathetoolsneedtobegroundtocertainanglesbuttheanglesdonrsquothavetobeexactFormosttoolssomewherehandywilldounless you are grinding a form tool to a particularly accurateshapeIthasbeennormalforbookstoshowtheanglesontoolsas used in a production environment where tools will ideallyhavealonglifeoftenthislifeiscalculatedaslastinganeight-hourshiftsothetoolonlyhastobesharpenedandresetonceadayInthehomeworkshopwecan increasethesecuttingangles

andgetbettercuttingattheslightexpenseofshortertoollifeWehavealreadyexplainedtheshapesof the tools thatyou

willfindmostusefulToolanglesareknownbytechnicaltermstop rake front rakeside rakeandback rakeThe rakeanglesvary depending on thematerial to bemachined but a set ofstandardtoolswillgetyoustartedSomeoftheaccompanyingphotographsareactuallyoflarge-scalewoodenmodels

Theleft-handtoolissuitableforbothfacingandturningtheright-handtoolissuitableforturningonly

Left-handsideofthefacingandturningtoolshowingthefrontandtoprake

Topofthefacingandturningtoolshowingthefrontandsiderelief

Left-handsideoftheturningtoolshowingthefrontclearanceandthetoprake

Topoftheturningtoolshowingthefrontandsideclearanceandthetoprake

GRINDINGATOOL

WhengrindingHSStoolstrytokeepthemascoolaspossibleIfan HSS tool becomes too hot and is then quenched in waterminutecrackswillformonthecuttingedgesThesecrackswillmakethetoolcuttingedgebreakdownveryquicklywhenusedThe best practice is to grind a little bit off the tool and thenquenchitwhileslightlywarmDonotletthetoolgethotdipitin thewater little andoften This should ensure the tool edgedoesnotbreakdowninuse

GrindingYourFirstTool

Most angles can be ground by using the tilting table whileothersmayneedtobefixedinrelationtotheperipheryofthegrindingwheelThefrontandsideofthetoolcanbegroundbytippingthetableatthecorrectanglewhereasthetoprakecanbegroundontheperipheryofthewheelThegrinder should first be switchedoff andunplugged Set

thetoolresttotherequiredangleusingthedigitalanglegaugeoranangletemplateandtightenuptherestBefore switching on the grinder ensure that everything is

freetorotatebyspinningthegrindingwheelbyhandIf all is well put on your safety glasses and switch on the

grinderPlacethetoolonthetoolrestupagainstthesideoftheprotractor Slide the tool along the table until it reaches thegrindingwheel andmetal starts to be removed Slide the toolbackwards and forwards slowly along the restwhile putting alittle light pressure on the tool so that it continues to pressagainst the grinding wheel When you have removed a smallamountofmaterialcoolthetoolbitdownAtnotimeallowthetool bit to get hot Continue grinding until you have removedsufficientmaterialfromthetoolbit

Thegrindingrestissettothecorrectangleof10degreestogrindtheendofthetool

Grindingthefirstangle

TurnthetooltotheotherangleanddothesamesothatnowboththefrontandsideclearanceangleshavebeengroundThis toolwill be enough for brass but for steelwe need to

grindthetoprakeWhengrindingthetoprakeonaright-handtool the slide rest needs to be higher than the centre of thegrinding wheel so that it grinds the tool at approximately 10degrees

Thefirstanglehasbeenground

You have now ground your first lathe tool The tool asreceivedfromthegrinderwillbetooroughtousehoweversoyouwillneedtohonethecuttingedgesYoucandothisonanoilstone(usedwithfineoillike3in1)orwithadiamondlaporusing a combination of the two Lightly lap the front and sideclearanceanglesuntilyougetagoodfinishand lightlyhoneaverysmallradiusonthetipofthetoolFinallyhonethetoprakeangleandyourtoolisreadyforuse

Grindingthesecondangle

Thesecondanglehasbeenground

AllofyourHSSturningtoolscanbedoneinthiswayOnlytheangleswillvaryandthesecanbesetusingadigitalanglegaugeandprotractorAnoccasionalhonewillresharpenyourtoolsaslongasyoutreatthemwithcareA similar range of HSS tools and a parting off tool all with

zero top rake shouldbeavailable if youwill be turningbrassUnless you are doing quantity production one tool holdershouldbesufficientforbrassAsatoolforbrasshasnotoprakeandyouwouldnotnormallygrindthetopawayaslongasyoubuy tool steel of the same size the tip height will remain thesameYoucanthenusethedifferenttoolsinoneholderwithouthavingtoresettheheight

MACHININGCASTIRON

Carbide-tippedtoolsareidealformachiningcastironAsimplebrazedupcrankedtoolwithasmallchamferonthenosewilldoforbothturningandfacingcastironcomponentsThemainuseof this tool will however probably be truing up the faceplatethat comes with the lathe The large diameter combined withtheintermittentcutovertheboltgrooveswoulddestroyanHSStoolinafewsecondsAsmalltippedboringbarwillbeidealfor

taskslikeboringcastironcylinders

Grindingthethirdangle

Asimplediamondlap

Thethirdanglehasbeenground

Tosharpentippedtoolsyouneedadiamondwheelorifyouwant to remove large amounts of carbide a silicon carbidewheeloftencalledagreengritwheelowingtoitsusualcolourSilicon carbide wheels are much softer than aluminium oxidewheels as they need to break down faster to present newsharpergrainstothecarbidetoolAdiamondwheelisonlydesignedtolightlylapatippedtool

itisnotsuitableforremovinglargeamountsofcarbide

Diamondcupwheel

TOOLHOLDING

Smallerlathessuchasarefoundinmostworkshopsmayhaveatopslidewithatoolclampforindividualtoolsablockwithasingle slot to take the tool a four-way turret (or sometimes athree-way)oraquick-changetoolblockandholdersetThereisalsotheso-calledAmericantoolpostwhichisaroundbarwitha slot through it and a bolt in the top to clamp the tool ItusuallycomeswithmatchingdishedwasherstoadjustthetoolheightThistypeisnolongerverycommononlathes

Quick-changeToolPost

Themostversatiletoolholdingsystemisthequick-changetoolblockwithmatchingholdersThedrawbackwiththissystemisthe cost of extra tool holders you need quite a few one foreachtoolThequick-changetoolblockmountsonthefrontofthelathe

normallyontopofthetopslide(Blockscanbefitteddirectlyon

thecrossslidebytheuseofaraisingblocktoaidrigidity)

Quick-changetoolblock

Each holder is set up with its own particular tool The toolholderscanbe individuallysetso that the turning tool isdeadoncentreheightandispresentedcorrectlytotheworkpiece

Quick-changetoolholder

Quick-change tool holders are available with a straight cutslottotakestandardsquareshanktoolholderswithastraightcutwiththeadditionofaVeecut-outinthebottomforusewithroundtoolssuchasboringbarsandasafrontpartingoff tool

holdertotakeahighspeedsteelpartingoffbladeRearpartingoff tool holders are available to take an inverted parting offbladeeitherahighspeedsteelbladeoran insertedtipbladeLeft-handed and right-handed extended tool holders are alsoavailableandmayoccasionallybequiteusefulThetoolblock isnormallymountedonthetopslidebutyou

cangetraisingblockstouseinsteadofthetopslideThismakesthetoolholderblockmuchmorerigidAbackquick-changetoolblockwillneedmountingonaraisingblock

Backofaquick-changetoolholdershowingthedovetailtypeofmounting

Right-handandleft-handextendedtoolholders

StandardtoolholderwithaVeetotakeroundtoolholders

Frontpartingofftoolholder

ToolClamp

Satisfactoryworkcanbedonewithatoolclampedontothetopslideusingshimsteel toset thecentreheightof the toolThemaindrawbacksarethatyoulosethepositionofthetoolwhenyoutakeitoffthetopslidetofitthenexttoolandyoualsolosetheaccuratecentreheightofthetoolunlessyoukeepthetoolandshimstogetherIfyouaremakingonlyonecomponentthisisnotaproblembutitisanuisanceifyouaremakingabatchofmatchingcomponents

Simpletoolclamp

Single-slotBlockToolPost

AblocktoolpostisoftensuppliedwiththecheaperlathesThetoolpostisliterallyablockofmetalwithaslotcutinittotakethe turning tool It is relatively easy to set the tool up at thecorrectcentreheightbyusingvariousthicknessesofshimThisisfineforthebeginnertoturningwhoisjuststartingoutbutitisbesttoreplaceitwithafour-waytoolpostoraquick-changetool post You could of coursemake several block tool postsandkeepeachonesetwithadifferenttool

Four-waytoolpost

Backtoolpost

Four-wayToolPost

Four-wayToolPost

Thefour-waytoolpost isagoodcompromiseona latheasyoucansetfourtoolsintheturretandrotateeachoneintopositionas needed This speeds up production and is a lot faster thanusingasimpletoolclampThedrawback isthatthetoolsstickoutof the turret fourdifferentwaysandyoumightcatchyourhandonasharp toolAsimple ratchetstopensures thateachtool repeats its position when the tool post is rotated so theworkisaccuratelyturnedeachtimethetoolisusedAduplicatefour-waytoolpostwithtoolsforbrasswillspeedupproductionevenmoreCastingsareavailabletomakeyourownthree-waytoolpost The three-way toolposthas theadvantageofbeingable to get close to the work when you are turning betweencentresFor the front tool post I would recommend right-hand and

left-hand roughing tools right-hand and left-hand finishingtools a tool groundup to face barswhile using a half centreand a Mini Thin inserted tip grooving tool with grooving andparting off inserts You will also need large and small boringbarsbothHSSandwithinsertedtipsTheHSStoolsshouldbegroundupforuseasgeneral-purposeturningtoolsformildsteelandsimilarmaterialsThecarbideinsertedtipboringbarshouldbefineforcastiron

BackToolPost

You can fit a quick-change tool block to theback of the crossslideaswellasthefrontSpecialholdersareavailabletotakeaHSSparting off blade or an inserted tip parting off blade Thebladewill be angleddown to give top clearancewhenpartingoffTheseback-mountedtoolblocksareveryhandyastheycanalsobefittedintotoolholderswithafacingtoolorachamferingtoolFor a back tool holder set-up I would recommend an HSS

partingoffbladeafacingtoolforcastironandadouble-ended45-degree chamfering tool that can be mounted parallel with

the chuck or at 90 degrees to it This set-upwill allow you tofaceaworkpiecechamfertheoutsidediameterandortheboreandpartitofftolengthThenextchapterlooksatholdingworkinachuck

5WorkholdingintheChuck

This chapter covers the different types of chucks how to usethemandsetupworkinthemaccurately

Aself-centringthree-jawchuckfittedwithlsquodrilljawsrsquoNotetheexternaljawswhichareinterchangeablewiththedrilljaws

USINGCHUCKS

Themostusefultoolsforworkholdinginthelathearethree-andfour-jaw chucks The three-jaw chuck is usually of the self-centringvarietythistypeofchuckcomesasstandardwithtwosets of jaws The first set of jaws are known as inside or drilljaws as they are most useful for holding round and hexagonbarsTheother setof jawsareoutside jawswhichholdworkusuallyindiscformontheoutsideSelf-centringmeansthatwhenyouinsertabitofbarintothe

chuck and turn the chuck key the chuck centralizes theworkpieceas it tightensup It isunlikely to runperfectly truebutitshouldruntruewithin3or4thouYou can also purchase soft jawswhich are exactly as their

namesuggestsYoucan thenbore themout to fit thework Ifyouborethemonthelatheyouaregoingtousethemontheworkwillrundeadtrue

Asetofsoftjawscanbeturnedorboredtosuittheworktobeheld

Aself-centringfour-jawchuckThesealsocomewithexternaljawsandsoftjawsareusuallyavailable

Self-centring four-jaw chucks can be used for square barsTheyarealsousefulforholdingroundbarswithmoregripthanathree-jawself-centringchuckSoft jawsarealsoavailableforfour-jawself-centringchucks

Afour-jawindependentchuck

Youare howevermuchmore likely to comeacross a four-jaw independent chuck than a four-jaw self-centring chuckIndependent means that the jaws can be moved individuallyand the jaws can also be reversed one two three or four ofthemdependingontheworktobedone

Abaseplatecastinginafour-jawindependentchuck

Wewillfirstlookatthethree-jawchuckThebestmethodofmaking a component in one of these is if possible to turn itcompletely at one set-up If you put a piece of bar into thechuck face the end centre drill drill and ream it skim thediameterandpartitoffitshouldbeconcentricalloverThisisbecausewehaveturneditallatthesamesettingwithouttakingit out of the chuck If we need to machine the other endhoweverwhenwe turn it roundandput it back in the chuckthechancesareitwillnotruntrueThis iswherethe four-jaw independentchuckcomes inYou

canput thecomponent intoa four-jawchuckandset it to runtrueusingthedialtestindicatorAnyworkyoudoonthepartedoff end should then be concentric with the rest of thecomponentWhensettingworkinafour-jawindependentchuckfor a second operation use some thin shimbetween the jawsandtheworkpiecetoavoidmarkingtheworkWorkisoftenheldinafour-jawchuckbecauseitisacasting

anoddshapeorsquareandsowonrsquotfitintoathree-jawchuckIf thework just requires tobe faced flat rightacross the facethereisnoneedtosettheworkrunningradiallytrueItshouldbe near enough on the centre line as long as the work is

reasonablybalancedYou could of course put the component into a three-jaw

chuckbyfittingsoft jawsandmachiningorboringthemouttotake the component This is the best option ifmaking severalcomponentsthatneedtobeidenticalbutifyouonlyneedoneor two components a four-jaw independent chuck will be thequickestmethodofmachiningthemLargerdiameterscanbeheld ina three-jawchuckbyusing

theoutsidejawsThesehavealargeradiusontheinsideofthejaw ifthisradiusis largerthantheworkpiecethejawsshouldnot tend to dig into the work and mark it Outside jaws areuseful forholding components like small flywheels locomotivewheels and chuck backplates when machining the bores ofholesorwhenmachiningacrossthefaceWhenmachining thindiscs it isuseful toputsomepacking

behindthedisctomakeitstandproudofthejawsTostopthepackingflyingoutwhenthemachineisrunningmakeasetofthree or four packing pieceswith grooves at each end and fittensionspringstothemTheyshouldallbethesamediametersothatthebackoftheworkisparalleltothechuckThelengthand grooves can vary slightly as they donrsquot affect theparallelismTheyarequickandsimpletomakesoacoupleofsets of different diameters should find their way intoeverybodyrsquostoolbox

AlthoughmostlathechuckkeyshavesquareendstheyareoftenofdifferentsizesKeepeachkeywithitsownchuck

ChuckKeys

I have alreadymentioned that the chuck key should never beleftinthechuckwhenitisunattended(seeChapter2)PutthekeyintothechuckuseitandputitsafelyawayassoonasyouhavefinishedwithitIfyouswitchonthelathewiththekeystillinthechuckyoumightneedatriptothehospitalDonotuseexcessive forcewhenyou tightenup the chuck

Do not use a piece of tube a spanner or anything else as alever thechuckkeyon itsownshouldbesufficient to tightenthechuckontotheworkWhenusinga four-jawchuckasmallchuckkey littlemore

thanaknurledknobwithasquareoncanbeusedtoadjustthejawsinandoutpriortotighteningupwiththeproperchuckkeyThiswill save timeover adjusting the jawswith a large chuckkeyTo turn the independent four-jaw chuck jaws round a

carpenterrsquosbracewithapieceofsquarebarinittofitthechuckwillmakeshortworkofreversingthe jawsbutdonrsquotuse it forthefinaltighteningasitisliabletostrainthejaws

STARTINGTOTURN

Before going any further you need to learn how to do basicturningFor thisyouneed toput the three-jawchuckonto themandrelStartbycleaningthemandrelwithacleanbitofragorsimilar(Ikeeparollofpaperkitchentowellingintheworkshop)Nowyouneed toclean thechuckrsquosboreand threadusing thetwotoothbrushmethod(seeChapter2)BoththemandrelandthechuckshouldbecleanbeforeyouattempttofitthechucktothelatheSelecting and grinding turning tools has already been

discussed (see Chapter 4) so by now you should have acorrectlygroundturningtoolsuitableforroughingoutapieceofsteelbar

Barwithapiptoolaboveorbelowcentreheight

MakingaToolCentreHeightSettingGauge

Thistoolneeds itscuttingedgesettothecentreheightofthelatheThereareseveralwaystodothisbutoneoftheeasiestiswith a home-made height gaugeWhen starting out this is achickenandeggsituationyouneedtomakethegaugetosettheheightbutyoualsoneedatoolsetatthecorrectheighttomakethegaugeThesimplestwaytoovercomethisproblemistosetthelathe

tooltotheapproximatecentreheightandtakeacutacrossthefaceofthebarDependingonwhetherthereisapipremainingon theendof thebaryoushouldgetan ideahow farout thetoolheightisIfthereisnopipthismeansthetoolisoncorrectcentre height or too high A pipmeans the tool is too lowOfcourse you may have been lucky so try dropping the toolslightly until a pip remains You can then raise the tool a fewthouatatimeuntilthepipdisappearsThetoolshouldthenbeoncentreheight

Barwithnopiptooloncentre

Nowthatthetoolisatcentreheightyoucanmakeasimpleheight gauge Turn a piece of bar down to as close to frac12in(12mm)asyoucangetandleaveitinthelathechuckMeasurefromthetopofthecrossslidetothetopofthebarwithacheapheightgaugeLowertheheightgaugebyhalfthebardiameterTheheight

gaugeshouldbeexactlyonthelathecentrelineMakeanoteofthisdimensionWe now need to look at how to turn a bit of bar to an

accuratediameterWhenturningabartosayfrac12in(12mm)youneedtostartwithsomethingslightlylargerInthiscasethiswillbe⅝in(16mm)diametermaterialasthisisastandardsizeCutapieceofmaterialabout2in(50mm)longandputitinto

thechuckwithabout1in(25mm)stickingoutSkimtheoutsidedown to about 0510 thou or 1225mm which is 10 thou(025mm) above the size required (You should be aware thatmosthobbylathedialsremovetwicewhattheysayaonethoudivisionforexamplewillusuallytake2thoufromthediameterLargercommercial lathesaremuchmore likelytotakeoffonethoupergraduation)Nowtakesmallcutsuntilalmosttosizeusingpowerfeedif

you have it andmaking sure you knock the feed off before ithitsthechuckStopthelatheandwindthecarriagetothestart

of the bar Take another cut at the same setting andmake anoteofthediameterTakeanothershallowcutbutthistimegoonly about frac14in (6mm) along the bar knock the feed off andturn the lathe off Move the carriage towards the tailstock sothat you can measure the bar Continue making this cut andmeasureuntilthesizeiscorrectThenrunthetoolalongthefulllengthof the jobWindthecarriagebacktowardsthetailstockand take a finishing cut or two at the same setting ThediametershouldnowbetheexactsizerequiredIt is not difficult to turn accurately it just takes a little

patienceandpracticeThemoreturningyoudotheeasieryouwill find it is to hold accurate limits If you turn everythingaccuratelywhetheritneedstobeaccurateornotyouwillsoonlearntoturnwithinathouorsowithoutanyproblems

Measuringtheheightofthebarabovethecrossslide

Now we need to make a tool height setting gauge Cut alengthofbarjustoverthedimensionsyouwrotedownandfaceone end turn it round in the chuck and face the other endMeasurethelengthandfindouthowmuchyouhavetotakeoffit to give the dimension you want Put the bar back into thechuck and bring the tool up to the face of the bar Lock thecrossslideFacethebartolengthbyusingthetopslideindexmovingforwardsafewthouatatimeuntiltherequiredlength

is reached Younowhavea tool height settinggauge suitableforthefrontandreartoolsIf you have an inverted Vee bed lathe or if for any reason

youcanrsquotusetheheightgaugeflatonthebedyoucanputtheheightgaugeonaplateon topof the lathebedwhileyouaresettingthetoolheight

Settingtheheightgaugetothelathecentreheight

Settingtheheightofthetool

Usingthesettinggaugetosettheheightofthereartool

TurningtoaSpecificLengthandDiameter

Nowwewill turnabarwithastepon theendToensure thatthestep isthecorrect lengthwewilluseabedstopThiscanbe as simple as a block clamped to the lathe bed to stop thecarriage moving any further I use a simple home-made bedstopthatdoesallIrequireSetthebedstopthenmovethecarriageuntilittouchesthe

stop and lock it Wind the top slide so that the tool is justtouching the end of the bar and lock the carriage For thisexercise we will make the step 16mm long and 12mm indiameterWindthetopslidealong159mmWecannowroughout thestepateachendTurn theenddown toabout02mmabove the finisheddiameterbywinding thecarriagebackandforthYoucanusethe fine feedbutmakesureyouknockthefeed off before the carriage reaches the stop and finish up tothestopbyhandWindthetopslidealongtheremaining01mmto12mmandfinishthediametertosizeandlengthtakinglightcuts as previously Donrsquot forget to clean up the face of theshoulderyouhavejustturnedIfyouneedtouseabedstopatthetailstockendofthelathe

asimplemethodofdoingthisistouseabarplacedonthelathe

bed against the tailstock The bar acts as a stop when thecarriageiswoundbacktowardsthetailstockThistailstockendbed stop is useful when you are turning a groove in acomponentandyouneedstopssetatboth theheadstockandtailstockendsofthelathe

Ahome-madebedstop

TurningWorkontheOutsideoftheInsideJaws

Theoutsideoftheinside(drill)jawsareusefulforturninglargerdiameterwork that is too large to fit inside thedrill jawsThiswillmostoftenbe in the formofa flywheelcastingFlywheelswithsixspokesareidealforturninginathree-jawchuckasthespokes can fit between the chuck jaws Ideally you need totighten up the flywheel until it is tight but not so tight as todistorttherim

TurningasteponabarusingthestopThebarisheldinthethree-jawchuckandsupportedwiththetailstockcentre

Ausefultailstockendbackstopmethod

Holdingaflywheelinathree-jawchuck

Holdingaflywheelintheoutsidejaws

To ensure concentricity you should do as much work aspossibleonthecastingatthesametimeYoushouldbeabletoturntheoutsiderimofthecastingfacetherimfacethebossand drill bore and ream for the crankshaft all at the samesettingAllyouneedtodothenistofittheoutsidejawsreversethecastinginthechucktapitgentlybackontothestepsoftheoutsidejawsandfaceacrossthesecondsideoftherimandthehubUseabitofshimtoprotecttheflywheeldiameterItdoesnotmatter if the flywheel runs exactly true or not as you areonlyfacingitparallelandtowidthnotturninganydiametersto

size

UsingtheSoftJaws

Soft jaws are very useful when a component has to run deadtrue in the jaws for example when making something like agrindingspindlewhereconcentricityisimportantSoftjawslikelytobefoundinthehomeworkshoparesimple

rectangles of steel with the scroll and groove formed directlyintothesoftjawsAnothertypeofjawyoumaycomeacrosshasa grooved pattern in the main jaws that matches a similarpattern in theactualsoft jawsThesoft topsof these jawsareusually interchangeable They are more likely to be found onlarger chucks but you could make your own version for thesmallersizesofchuckifyouwishThemain use of soft jaws is for second operationwork for

examplewhenyouhaveturnedacomponentcomplete fromabitofbarandparteditoffNowyouneedtoholdthecomponenttruetofinishoffthesecondendYoucandothisbyboringoutthechuckjawstotheexactdiameteroftheworkpieceToborethesoft jawstheyshouldbetightened inthesame

direction as they will be tightened in use so that they areoperatingonthesamepartofthechuckscrolleverytimeIfyouhaveathincomponenttomachinefitthesoftjawstothechuckandtightenthejawsontoabitofbarheldinthechuckBesureto leaveenoughspace in frontof thebarsoyoucanbore thejawstofitthework

BoringsoftjawstofittheworkThejawsareclosedontoanoddmentofbartoturntheshallowregistersothatittakesthework

AlwaysusethesamechuckkeyholewhentighteningupthejawsThisappliestoanythingyoudowithaself-centringchuckStampacrossoracentrepopmarkagainstoneof the jaws IsuggestdoingthisnexttojawNo1butanyonewilldoaslongas you always use the samemarked hole Youmight as wellmarkallyourself-centringchucksinthesamemannerCarefullyborethejawstotheexactdiameteroftheworkto

be machined Try to get it exactly on size Undo the jawsslightly remove the bar and replace it with the workpiecewhichshouldnowrundeadtrueAusefulmodificationtothesoftjawsistodrillandtapahole

inthemiddleofthejawsandfitanAllenscrewtoeachholeIfyouwant toholda longbar in thesoft jaws it isnoweasy toboreallthewaythroughthejawsratherthanjustboringastepor part way through All you need to do now is find a disc ofmaterial to put into the chuck ensuring there is sufficientmaterialleftontheinsideedgesofthechuckjawstoborerightthroughtotakethebar

Holdthedisconthescrewheads ifnecessarydrillthediscbeforeboringBorerightthroughthediscandthejawsuntilyouarenearlytosizeatwhichpointyoucanborethroughthediscand test the resultingborewith theworkpieceMakesureyouclean the bore thoroughly before trying the workpiece sinceloose dust can make the hole seem smaller than it really isWhentheworkpieceenterstheborefinishboringrightthroughthe jawsgo througha coupleof timesat the samesetting totakeoutanyspringintheboringbarYoucannowremovethedisc clean the jaws and put the workpiece right through thechuckcheckingthatitrunsdeadtrueThisoperationmaysoundtimeconsumingforasingle item

but if you have several components to make it will save aconsiderable time on setting up each bar individually to runtrue

BoringsoftjawsusingaringThesoftjawshavethreeAllenscrewsthatarecloseddownontotheringwhileboring

TurningtheoutsideofthesoftjawsusingaringThesoftjawshavethreeAllenscrewsthatareopenedupontotheringwhileturning

NowthescrewsareinplacewecanworktheotherwayroundandholdcomponentsontheoutsideofthejawsTodothisyouwillneedaringofasuitablesizeontowhichyoucantightenthejawswith the jaw loading acting outwards so any componentyouputontheoutsideofthejawswillberunningconcentricallyThiswill be ideal for itemssuchas tractionenginewheel rimsandotherlargehollowortubularworkpiecesOne other use for soft jaws is to hold irregular-shaped

components Put a piece of bar into the soft jaws and bore aholeofanysizeand thencleanup theboreso thatallof thejawsare true Transfer the chuck to themillingmachine tableandclampitdownUseatestindicatortocheckthattheholeinthechuckistrueYou can now mill a nest to take any irregularly shaped

component confident that when the chuck is returned to thelatheitwillberunningtrue

Plungertypedialtestindicator

Levertypedialtestindicator

DialTestIndicators

Therearetwomaintypesofdialtestindicatortheplungertypedial test indicator as its name suggests works on a plungerprinciplewhilethelevertypedialtestindicatorhasastylusonthe end The lever stylus is usually ball-or pear-shaped and isfixedtothedialtestindicatorwithafrictionfitmeaningthatitcanbemovedupanddownontheendofthedialtestindicator

throughawidearctoputitintothebestpositionforuseThe plunger type dial indicator usually has a maximum

plungermovementoffrac12in (12mm)butplungermovementsofupto2in(50mm)areavailableTheplungertypedialindicatoris non-reversing and needs an adaptor to enable it to clockholes true Instead of a stylus it has an interchangeable endoften with a ball fitted various interchangeable ends areavailableoryoucanmakeyourownThe lever dial test indicator has a much smaller range of

travelarangeof0008in(02mm)isverycommonItisusuallyeither self-reversing (itmoveswhen in contact with theworkdependingonwhichwayitismoving)oritmaybereversedbyusinga lever on the sideof thedial test indicator both typesarequite commonSince the stylus isdelicate combinedwithitslimitedtravelrangeyoumustbeverycarefulnottobreakitAplungerdialindicatorcanbeusedasadirectreadoutofthe

travel and will be found to be very accurate Owing to therelativelylongtravelifyouwantedperhapstooffsetthecentreofabitofbar in the four-jawchuckby0125in (318mm) thiscanbedonebyturningthechuckbyhandandsettingthebaruntil the indicator travel shows 0250in (635mm) which is0125in (318mm) offset The lever dial test indicator is of nouseforgivingdirectreadingslikethisbutshouldbeusedasacomparatorwherethereadingtakenisforexamplezeroatallpointsofthetravelThedial test indicator is usuallymounted on amagnetic or

vacuum base but is sometimes fixed to a block that can beclampedtothelathemostoftenonthecrossslideSometimesthedialtestindicatorcomesasacompletekitincludingvariousmountingcomponents

Clockingtheendofacastinginafour-jawchuck

Four-jawChuck

To set thework up in an independent four-jaw chuckwe firstneed to know what part of the workpiece should be on thecentre If theworkpiece is a castingwemay have an outsidediameter or a hole that needs to run true in this case wewould put a dial test indicator onto the work and adjust thechuckalittleatatimeuntilthediameterrunstrueDonotturnthe chuck with the indicator in the hole Instead wind thecarriage forwards until the clock enters the hole and take areadingWind thecarriageback rotate thechuck90degreeswindthecarriageforwardandtakeanotherreadingAdjusttheworkinthechuckuntilitrunstrue

WhereacastingisstickingoutashereyoushouldtrytosupportthecastingwitharunningcentreThiswillhelptostopthecastingshiftinginthechuck

LatheCentreFinder

If there isnodiameterorholeyoumayhave tomarkout thecentreontheworkusingaheightgaugeandcentrepopitwithacentrepunchThenyoucanuseawobblerandatestindicatortosettheworktrueItwasoncepossibletogetalathecentrefinderconsistingof

a bar about 6in (150mm) long pointed at both ends with auniversaljointabout1in(25mm)fromthefrontendInusetheshortfrontendgoesinthecentrepopoftheworkinthechuckWhen you rotate the chuck by hand the pointed short endfollows the eccentricity of the centre hole which ismagnifiedaboutsixtimesatthetailstockendYouthenjusthavetoadjustthechuckuntilthetailstockendisrunningtrueatwhichpointthe centre in the work will also be running dead true I donrsquotknow anyone who makes these and second-hand ones areextremelyrare

Asimplehome-madecentrefinder

You can make a simple version of this that works well byusingamillingmachinepointedcentrefinderThisisaparallelbarwithaseparatemoveablepointedendThetwocomponentsare held together with a spring inside You need the pointededge finder a Morse taper parallel adaptor (the Morse tapershould fityour tailstock)aspringandashortstubofbar thatwillfitinsidethetaperedholderrsquosboretostopthespringgoingrightthroughPuttheshortstubofbarintothetaperinsertthespring follow up with the centre and put the Morse taperadaptorintothetailstockBringthetailstocktowardsthechuckuntil the centre of the centre finder is in the centre pop ThespringwillholditinplaceTousetheimprovisedcentrefinderput a dial test indicator onto the parallel part of the centrefinderrsquospointandrotatethechuckbyhandThepointwillrotateeccentricallyadjust thechuckuntil thecentre finderrsquospoint isrunningtrue

Usingascribingblockwithadialtestindicator

Move the tailstock along the bed until the point of thewobblerisinthecentrepopontheworkPutthetestindicatoronthefrontdiameterofthewobblerandadjustthechuckjawsuntilthewobblerisrunningtrueWhensettingupacastingorsomethingsimilarwherenotall

of the diameters are machined you should use the dial testindicator on diameters thatwill not bemachined such as theinsideofaflywheelrimWhenyouhaveturnedallthefinisheddiameters they should then be true with the unmachineddiametersSetting work in the four-jaw chuck depends on the

componenttobemachinedIfyouareusingroundmaterialyoucansetittoruntrueusingadialtestindicatorHoweverifyouaresettingaroughcastingthevariationofsizeandroughnessofthecastingsmaywellbeunsuitableforadialtestindicatorThere are alternativemethods of settingwork up in a four-

jawchuckespeciallyforcastingsOneofthesimplestmethodsis toholdasquarebar in the lathetoolholderandusethis tosetthejobtrueInuseyouwindthebaruptotheworkandsetthedial tozeroorotherwisemakeanoteofwhere it isWindthebaroutorawayfromtheworkTurnthechuck180degreesand wind the bar up against the work again You can

immediatelyseewhichwaythebarneedstomovesothatitisrunningtrueAdjustthecastinginthefour-jawchuckandmovethecastingtowardsthecentrepointRepeatuntilthecastingisrunning true This method is also useful if you are setting asquarebar to run true Justcheckeach faceof thesquarebarwiththebitofmetal

Settingacastingbyusingasquarebar

StickyPinMethod

An alternative the sticky pin method is especially suited tolocomotive wheels or flywheels An ordinary household pin ismounted in plasticine or Blu-tack perhaps stuck on the lathetool and is arranged to point to the inside diameter of thewheelor flywheel thearea that isnotmachinedbut is leftascastAdjustthecastinguntiltheunmachinedfaceisrunningastrueasyoucangetitandthewheelisreadytoturnThestickypinmethodisalsousefulforsettingupworkthathasachuckingspigot such as a locomotive smokebox door Just hold thechucking spigot in the four-jaw chuck and adjust the castinguntilitrunstrueontheoutsidediameterandthefrontface

Usingacommercialstickypintosetworktrue

Themethodsofcentringworkinthefour-jawchuckthathavebeen discussed are also suitable for setting work true on thefaceplate The next chapter looks at turning between centresandusingthefaceplate

6TurningbetweenCentresandFaceplateWork

Thischapterdealswithbasicturningbetweencentresandthenintroduces turning with the work mounted on the lathefaceplate

Headstockcentreanddriverplate(alsoknownasacatchplate)

TURNINGPLAINBARSBETWEENCENTRES

The most basic way of holding work for turning is between

centres Turning between centres is literally holding thecomponenttobemachinedbetweentwocentreseachofwhichhas a 60-degree included angle The headstock centre usuallygoes round with the headstockmandrel although some olderlatheshadanon-rotatingcentreandthedrivetotheworkwasbyapulleymountedontheworkThetailstockcentreisoftenafixedcentrethatdoesnotgoroundalthoughcentreswithballbearingscalledrunningcentresarereadilyavailable

Tailstockplaincentre

The component to be turned usually a shaft has a female60-degreecentreinbothendsthatisusedtosupporttheworkThe work can be turned round between centres so that bothends of the shaft can be machined Because the work ismountedbetweencentresbothendsoftheworkwillbetruetoeachother

Tailstockrunningcentreso-calledbecauseitrunsonballraces

CentringtheBar

FirstwehavetoputthecentresintoeachendofthebarIfthebarisshortsayuptoabout6inlongholdtheworkinthethree-jawchuckanduseacentredrillinthetailstockdrillchucktoputacentre intothebarAcentredrill isashortdrillwithasmallpilot on the end that has a 60-degree taper to the bodydiameterAbettermethodof centring thebar especially longbars is by using a three-jaw chuck and the fixed steady Thebarisheldinthethree-jawchuckwiththeotherendsupportedin the fixedsteadyand thecentre is formed in theendwithacentredrillAusefultoolthatcanbeusedtofindthecentreoftheshaftis

thecentresquarewhichisametalbladewithaVeeonitthatlocatesonthediameterofthebarMarkalineacrosstheendofthebarwitha scriber turn the centre square90degreesandthenscribeanotherlineWherethetwolinescrossisthecentreof thebar Tomake it easier to see the scribed linesblackenthe end of the bar with a permanent felt tip marker beforescribingCentrepunchthepointwherethetwolinescrossandput a 60-degree centre in each end of the bar using a centre

drill in a power drillHold thebar in a bench vicewhile doingthisPutacentredrillintothetailstockdrillchuckandinsertthebar in the three-jaw chuck Make sure the lathe is on a lowspeedabout300rpmwindthetailstockinandjustlightlycleanupthecentreholewiththecentredrilltotrueitupAnotherusefultooltofindthecentreofabarisabellcentre

punchThiscomprisesaconewithacentrepunchinthemiddleIn use place the bell end on the end of the bar and tap thecentrepunchwithahammertomarkthecentreTheendofthebar though needs to be reasonably square if using the bellpunchmethodThere are other similarmethods of centring bars but those

givenherewillbealltheturnerneedstolearn

Turningbetweencentres

Centringthebarusingthefixedsteady(Notethatthefrontclampisnormallydoneupwhileinuse)

Asimplecentresquare

Crosssectionofbellcentrepunch

MachiningtheBar

NowweneedtomountthebarbetweencentresThisissimplyamatterofputtingthebarbetweencentresandtighteningthetailstocksoitislightlypressingintothecentreintheendofthework To drive the work a carrier is fixed to the shaft andengagesapininacatchplatemountedonthelathemandrelAcatchplateissimplyablankdiscwithapinstickingouttodrivethecarrierthat isfittedtotheworkThecarrier isfittedtotheworkusinganAllenscreworboltTostopanymovementofthebarinrelationtothecatchplatethecarriercanbewiredtothecatchplatepinThiswill stop thecarrierand thework flappingaboutItisparticularlyimportanttostoptheworkfrommovingin relation to the catchplate when screwcutting betweencentres

Facingoffabarusingthehalfcentre

Nowthatthebarissafelymountedbetweencentreswecanstart turning it tosizeNormally the first thing todo is to facetheendsofthebartothefinishedlengthDecidewhichendofthebarhastheshallowercentreWewillmachinethisendfirstYouwillneedahalfcentreso-calledbecausealmosthalfofthecentre is missing This means the lathe tool can reach rightacrosstheendoftheworkwithouttouchingthehalfcentreWhenusinganyfixedcentreinthetailstockputabitofoilor

grease into the centre before use and top up as necessaryLightlywindthetailstockbarrelagainstthecentreandlockthebarrel so it canrsquotmoveSwitch the latheonandwind the toolacross to clean up the end Reverse the work and clean theotherendupat thesamesettingBothcentresshouldnowbethesamedepthMeasuretheoveralllengthofthebarTakethefinished length required from the overall measurement youhavejustmeasuredDividethisbytwoandthisishowmuchweneed to take off each end of the shaft so it finishes at therequiredlength

Askimmedbar

Ifyouhaveonechangethetailstockhalfcentretoarunningcentre if you donrsquot have a running centre change to a fixedcentreThehalfcentreshouldonlybeusedwhenfacingtheend

of the bar We will nowmachine the rest of the bar For thepurposeofthisexamplewewillassumethebarhasafinisheddiameter in themiddle with a step at each end First we willmachine the overall diameter to size To do this we need toskimthediameterandcheckthesizeTakeafinecutalongthebarusingthefinefeedifyouhaveoneMeasurebothendsofthebar Ifyouhavesetthelatheupcorrectly(seeChapter2)thebarshouldbeparallelIfitisnotadjustthetailstockbeforecontinuingAssumingthebarisparalleltakeanothercutortwosothatyouareabout01mmlargerthanthefinisheddiameterNowmove the tool in until almost at finished size and take alight cut about 10mm long along the bar Repeat this cut toensure the tool is notpushingoffMeasure thisdiameter youwill probablyhave towind the tailstockbarrel back toget themicrometerontotheendofthebarOnlymovethebarrelbackdo not slide the entire tailstock backMeasure the bar to findouthowmuchtoremovefromthediameterTakeanothershortcutandcheckforsizeWhenthebariscuttingtosizemachineall thewayalongYouwillprobablyhave to take twoor threecuts at the same setting until the bar ismachined to finishedsizeNowwewill turn the stepson theends Toensure that the

stepsare thecorrect lengthwewilluse thebedstopSet thebedstopthenwindthetopslidesothatthetoolisjusttouchingthe end of the bar For this exercise we will make the steps12mm long Wind the top slide along until the tool is justtouching the end of the turned bar Wind the top slide along119mmWecannowroughoutthestepateachendTurntheenddowntoabout02mmabovethefinisheddiameterYoucanusethefinefeedbutmakesureyouknockthefeedoffbeforethecarriagereachesthestopandfinishuptotheendbyhandRepeat for the other end Wind the top slide along theremaining01mmto12mmandfinisheachendinthesamewayasyoufinishedthemaindiameterDonrsquotforgettocleanupthefaceoftheshoulderyouhavejustturnedCongratulations you have just turned an accurate shaft

Donrsquotworryiftheshaftisatinybitundersizeyoucanprobably

makethematingholestofit

Thefinishedshaft

Usingachuckandarunningcentre

Usingthemethodsetoutaboveyoushouldnowbeabletoturn any shaft you require within the capacity of the lathe Avariationoftheabovemethodwheretheshaftissingle-endedistoholdoneendinthethree-orfour-jawchuckandsupporttheotherendwithacentreinthetailstock

Alargefaceplatesmalleronesareavailable

FACEPLATEWORK

Another basic way of holding work is on the faceplate Thismethod is used when the component is too large or isawkwardly shaped andwould be difficult to hold in a three-orfour-jaw chuck Usually the work is clamped directly onto thefaceplate often with a packing piece behind it to protect thefaceplateThefaceplateshouldbeflatandtruesothefirstthingtodo

whenyougetthelatheistocheckthefaceplatewithadialtestindicatorCarefullycleanthemandrelnoseandtheinternalholeinthefaceplateMakesurethemandrelcanturnfreelybyhandwith the lathe switched off and check that the face of thefaceplateisrunningtrueasclosetotheouteredgeasyoucanget If it is runningtrue runthetest indicatoracross the frontfaceofthefaceplatethisshouldbetrueaswellIfthefaceplateis running out itwill need to bemachined Put the lathe intobackgear if ithas it (topbackgearwillprobablybe fine)Youwill need a carbide-tipped tool ideallywith a small 45-degreechamferonthetipBringthetooluptothefaceplateand lockthe carriage Next you need to lightly face the faceplate right

acrossitsdiameterIfyouhaveapowercrossfeeditwillmakelight work of this but if not you can feed across by handFortunatelymost faceplateshavea series of rings on them toaid in setting up the work Machine the faceplate from theoutsidetothefirstringandstopforarest feedtothesecondring and so on until finished Depending upon how badly outyourfaceplateisyoumayhavetodothismorethanonceuntilit iscleanedupbutwhen it isdoneyouwill rarelyneedtodothisexerciseagain

Machiningaholeinablock

Asmentionedpreviously the ringsmachined on the faceplateareguidestohelpyousetuptheworkThiswilldoiftheworkisaroundcomponentbutweneedadifferentmethodiftheworkis square Take a block of metal for example that has beenmachinedalloverWewanttomachineaholeinit2infromoneedgeand1in fromanother edgeMarkout thepositionof theholeandcentrepunch it Put adeadcentre into the tailstockholdtheblockontothefaceplatebringthetailstockuptowardsthechuckandlockitWindthetailstockbarrelandcentreuptothe component and engage with the centre pop Lock thetailstock barrel Clamp the block to the faceplate using somepackingpiecesandfourclampsontheblockTheholeisnowoncentreandwecanmachineitinthecorrectplaceIf we need more than one hole placed accurately in the

componentwecanusetoolmakerrsquosbuttonstoensuretheholesare in the correct place Toolmakerrsquos buttons usually come insetsof fourOnebutton isusually longer than the rest soyoucanstillclockthediameterwhenitisclosetoanotherholeSetsare often available second-hand on eBaywhile they probablyhaveanobscureAmerican threadyoucanclamp themto theblock using your own BA or metric screws together with awasher

Settingupthefaceplateusingthetailstock

Asetoftoolmakerrsquosbuttons

Tofitthemtothecomponenttobeboredmarkoutdrillandtap holes in the approximate positions where the holes areneeded If you need a pair of parallel holes place thecomponentonasurfaceplate looselyfitthebuttonsandpushthem down onto a parallel or similar block of the correctthicknessandnipthescrewsupThespacershouldbesmallerthanrequiredbyhalfthediameterofabuttonIftheholesneedtobeacertaindistanceapartuseaspacer

of the correct size between the buttons (Remember tomake

thespacersmallerbyonediameterofthebutton)

Settingupacomponentusingtoolmakerrsquosbuttonstogetafixeddistancefromtheedgeofacomponent

TherearelotsofdifferentwaystosetthespacingofbuttonsItismainlyamatterofcommonsenseCastingsandflatcomponentscanbeboltedtothefaceplate

for machining A typical example of a flat component is aneccentric strap This type of component is usually made of acomponentthatiscutinhalfandboltedbacktogetherAholeisthenboredinitonthecentrelinetofittheeccentricThistypeofcomponentisoftendifficulttoholdinthelathechuckandisprone to distortion Castings are often too large to fit into alathechuckandso the faceplate iscalledon toundertake theworkAcastingcanoftenbebolteddirectlytothefaceplatetofacilitateeasymachining

Settingupacomponentusingtoolmakerrsquosbuttonstogetafixeddistancebetweenthecentresofacomponent

Work on the faceplate is often an odd shape or is set off

centreThiscauses it tobeunbalancedandasaconsequencethe lathemayvibratewhile thework is turningTocounteractthis tendency the faceplate should be counterbalanced byboltingweightsontoitAusefulsourceofweightsisthelathersquoschange wheels By bolting a change wheel or two onto thelightersideofthefaceplateyoucanbringthewholeassemblybackintobalanceAfterboltingthechangewheelsonspinthelathe by hand to check the balance The faceplate should notshowatendencytostopatoneparticularpointWhenyouarehappy that the faceplate is in balance the work and balanceweightsareboltedontightlyandsothattheworkdoesnotfoulthe lathewhen turnedbyhand switch themachine on in lowback gear to check for vibration Depending on what you areturning you should be able to run in top back gear or evenbottomdirectspeed

Asimpleclampsetisveryusefulwhenmachiningacastingonthefaceplate

TurningaFlywheel

Oneofthemainusesofafaceplateisturningalargediameteriron casting typically a flywheel or a locomotive wheel for asteamengineTheflywheelshouldbemountedsothattheinneredgeoftherimandtheouteredgeofthehubruntrueIfeitherofthemrunsoutitwouldbebetterthatthehubrunsoutasthe

rimwillbemorenoticeableonthefinishedengineClamp the flywheel down with some packing under the

spokessothatyoucanturnrightacrosstherimBecarefulthatyouclamptheflywheeltightenoughsothat itdoesnotmovebutnotsotightthatitdistortsRoughturn theoutsidediameterand facetherimusingthe

backgearUsingadirectdrivespeeddrillandborethecentrehole and either finish off with the boring tool or use a reamDonrsquot try reamingwithout boring the chances are that if youdotheholewillnotbetruewiththerimasthedrillprobablydidnotcutanaccurateholeDropdowntothetopbackgearspeedface the rim and turn the outside of the rim to the finisheddiameter Turn the flywheel over and finish the other face towidth

Astubarborsuitableforcentralizingalocomotivewheelorflywheel

TurningLocomotiveWheelFlanges

LocomotivewheelflangescanbeturnedonafaceplateYoucanpurchase blank end Morse taper arbors that fit into theheadstocktaperFitoneoftheseandturnaspigotonittotake

thewheel bore Thewheel bores should all be the same sizebut if they are different sizes machine the spigot to fit thelargestboremachinetheflangeonthatonethenmachinethespigotdowntofitthenextonemachinetheflangeandsoonIdeally the wheel bores should all be the same size but if

theyarenotproceedas followsSkimtheoutsidediameterofthe wheel flangemeasure and take it to the correct finishedsizeMovethelathetoolinbythedepthoftheflangeandturnthe tread Deal with all wheels like this machining all of theflangeoutsidediameterstothesamesizemovinginthecrossslidebythesameamounteachtimesothatallthetreadsendupthesamesize

UsingtheKeatsVeeangleplatetoturnaneccentriccomponent

KeatsVeeAnglePlate

TheKeatsVeeangleplate ismountedon the faceplateand isusedtoholdroundbarsquarebarandmiscellaneouscastingssuch as cylinders and steam chests The angle plate can bemountedanywhereonthefaceplateaslongasthelathecanbe

rotated safely and is in balance When spun by hand thefaceplateshouldnotshowatendencytostopatanyparticularplacewhenrununderpowerthelatheshouldnotvibrateAswellasholdingbarandcastingsforturningtheKeatsVee

angleplateisveryusefulformakingeccentriccomponentssuchastheeccentricsforasteamengineTo turn an eccentric use a test indicator to check that the

roundbarisrunningreasonablytrueWhenthisissatisfactoryyoucanturntheoutsidediameterofthebartofittheeccentricstrap (or component) including any step or groove requiredNextoffsettheKeatsVeeangleplatebytheamountyouwantthe eccentric lsquothrowrsquo to be Use the dial test indicator tomeasure the offset of the outside of the eccentric The offsetshouldbetwicethethrowYoucannowdrillboreandreamtheholeintheeccentricYounowhaveenoughbasic knowledge to carryout turning

between centres andwork accurately on the faceplate In thenext chapterwewill lookat holdingwork in a collet andonamandrel

7ColletsandMandrels

Thischapterexplainsallaboutholdingworkinacolletandhowyou canmake and use several different types of mandrel forworkholding

ERcollets

USINGCOLLETS

Quite a few different collet systems are to be found inworkshops Some are used for holding tools such as millingcutterssomeareusedforbarorworkpieceswhilesomemaybeusedwithbothbarandworkpiecesOne of the commonest is the ER collet which comes in

severaldifferent sizeseachhavingadifferent largediameterTheERcolletsystemallowsupto0039in(1mm)collapseofa

colletalthough in thesmaller sizesyoucanbuy thecollets in05mmincrementsA16mmcolletforexamplewillholdroundmaterialdownto15mmdiameterWhatevertheERcolletsizetheyallappear togodownto1mmminimumwhichwillclosedownto05mm

ERcolletadaptor

TherearemanytypesandsizesofERholderavailableAlltheusualMorse taper shank sizes are available and you can alsobuyvariousdiametersofextendedparallel shankholdersTheproblemwiththeseisthattheyaregreatforholdingtoolsthathave a short shank but because you need to use the holderwithadrawbaryoucanrsquotputlongbarstockrightthroughthemTo overcome this for lathe work you can also buy ER colletholdersdesignedtobefittedtoachuckbackplatethatyoucanmachine to suit your lathe so ensuring good concentricityBecause they donrsquot use a drawbar you can fit bar stock rightthroughandintotheheadstockmandrel

ERcolletadaptorfittedtoabackplateIalwaysleavebackplatesoversizesoIhavesomethingwithwhichtoclampthemdownwhenusedonamillordrill

When buying new and second-hand ER collets make surethey have the retaining groove near the nose end The older(andobsolete)EandEScollet typesdonothavetheretaininggrooveandarenotinter-changeableYouaremostlikelytofindEandEScolletsincludedwithasecond-handUnimatlatheDraw-in collets are usedwith a drawbar or collet tube The

drawbardrawsthecolletuptightbydrawingit intothelathersquosmandrelbyabar that runs through thecentreof themandreland screws into the centre of the collet Thismeans that youcannotputbarstockrightthroughthecolletToovercomethissome Morse taper collets use a hollow draw tube the collethaving an external thread tomatch the internal thread of thedrawtube

Draw-incollet

Special collets are made for the Myford ML7 Super 7 andML10 lathes These are Morse taper collets but rather thanhavingadrawbartheyareclosedwithanoseringthatfitsoveragrooveinthecolletThenoseringtightensthecolletintotheheadstockmandrelrsquos Morse taper It is extracted after use byundoing the nose piece which draws the collet out from theMorsetaperbythenosegrooveImperialandmetriccolletsareavailableuptofrac12in(12mm)diameterDead lengthcolletsareavailable that fit intoanattachment

usually fixed to the front of the lathersquosmandrel These colletsarecalleddeadlengthbecausetheydonotmovelongitudinallyunlike draw-in collets You are more likely to find collets likethesesecond-handratherthannew

BoxedsetofMyfordcollets

Deadlengthcollet

AvariationofthedeadlengthcolletistheCrawfordMultiborecolletThissystemhascolletsmadeofsegmentsheldtogetherbyspringsThecolletsareofvariablediameterandhavequitea

largeclosurerangeTheyaremorelikelytobefoundonalargercommercial lathe although you can get collets for smallermachinesWatchmakerrsquoscolletscanbeused inmost lathesbymaking

an adaptor for the headstock and a drawbar (or tube)Watchmakerrsquos collets are very accurate and can go down toverysmallsizesbuttheyhavelimiteduseinmostworkshopsYou can get a special watchmakerrsquos spindle for the EmcoUnimatlatheandthereisalsoaversionoftheCowellslathetheCW90thattakeswatchmakerrsquoscolletsFormost of thework carried out on the lathe youwill find

thatanERholder thatmountsontoachuckbackplate ismostuseful

Simpleexpandingmandrel

Simpleplainmandrel

MAKINGMANDRELS

There are several types of mandrel in common use inworkshops The most common is probably the expandingmandrelwhichcaneasilybemadeinanyworkshopInitsmostbasic form it is a bar turned to a size to fit the bore in theworkpieceItisthenthreadedwithataperedtapandslitat90degrees togive foursegmentswhichare thenexpandedbyascrewfittedintotheendofthemandrelAnother common mandrel is the tapered mandrel This is

usuallyalsquobetweencentresrsquomandrelandisoftenmadetotaperfromjustacoupleofthouovernominalsizetoacoupleofthouunder nominal size It is usually hardened and has a groundfinishTheworkpieceisheldinplacebybeingpushedontothemandreluntilitistightToremoveitjustpressitbackoutthewayitwentinWhereconcentricityisnotquitesoimportanttheworkpiece

canbeputonaplain turnedmandrelandtightenedupwithaboltandflatwasherExpandingmandrelsarealsomadecommerciallybutasyou

need a mandrel for each individual size of hole it can getexpensive if you need more than one or two different sizesCommercialmandrelscanbeobtainedwithMorsetapershanksto plug straight into the headstock Thismethod ensures thatthe mandrel should run dead true assuming both the Morsetapermandrel and theMorse taper in the headstock are bothcleanandfreefrommarksorswarfYou can also purchase Morse taper arbors with blank end

pieces from which to make your own mandrels First we willmake an expandingmandrel from a blank Morse taper arborYouwillneedtoturnthearbordowntofittheworkpieceboreIusually turn themandrelabout0010in (0025mm)oversize tostartwithandthenIdrillandtapthearborwithataperedtapThe drilled hole can go quite deep but the tapped hole onlyneedstogoinuntilthelockingbolt isabouthalfwaydownthelengthwheretheworkpiecewillsitPut the mandrel into the vice and cut along the mandrel

making four cuts around the circumferenceRetap thehole to

cleartheswarf fromthethreadandputthemandrelback intothe headstock taper Now you can lightly nip the screw up toexpandthemandrelslightlySkimthemandrel to finishedsizeuntil the workpiece will fit on without shake You can nowfurther tighten the screw so that the workpiece tightens ontothe mandrel When you slacken the screw the workpiece willcome off easily as you have skimmed it while it was slightlyexpandedYoucanmakeanexpandingmandrelfromabarheldin the three-or four-jawchuckorperhapsacollet inasimilarway Ifheld inachuck itmaynotgoback true ifyouneed touseitagainsoifpossibleyoushouldholdthearborinacolletFor aplainmandrel turn thediameter to fit theworkpiece

anddrillandtapforacapscreworaboltThereisnoneedtosplit this type ofmandrel You simply put the workpiece ontothemandrelandholditonwithaflatwasherAgainitdoesnotmatterwhetheryouuseabarinachuckorcolletorifyouusea Morse Taper blank arbor Arbors are very useful in theworkshop If youmake them fromMorse taper blanks or holdtheminacollettheycanbeusedoverandoveragain

8TaperTurningandLatheAccessories

Thischapterexplainshowyoucanturnataperusingatopslidetheuseoffixedandtravellingsteadiesandformtools

Turningataperwiththetopslide

TAPERTURNING

SometimesyouwillhavetoturnataperintheworkshopThatisa fairly easy jobWhat ismore difficult however is having toturnmatchingmaleandfemaletapers

Themethodyouaremostlikelytouseintheworkshopistoturn the two tapers with the top slide You should be able toturna taper longenough foraMorsetaperusingthismethodThemostimportantthingwhenturningtapersistoensurethatthe tool tip is at the exact centre height of the lathe This isbecause the taper will vary if the tool is not dead-on centreheightProbably the easiestmethod of turning aMorse taper is to

useadial test indicator toclocka lathecentreof therequiredMorse taper between centres The smaller end of the tapershouldbeatthetailstockendofthelatheThetopslideshouldbewoundalongthetaperby itshandwheelwhilethecarriageremainslockedThetopslideshouldbeadjustedangularlyuntilthedialtestindicatorreadszeroallthewayalongNowyoucanfinish turn the external Morse taper using an internal MorsetapersleeveasagaugetocheckthattheangleiscorrectTodothis make marks with a felt tipped pen along the taper andcheck that the test sleeve rubs evenly all the way along themaletaperAdjustifnecessaryuntilyouhaveaperfectfitToturnthematchingfemaletaperthelargeendofthetaper

willbeat the tailstockendand theboringbarwillbe invertedandcuttingon thebackof theholeDoing thismeans thataslongasbothofthetoolsareatcentreheightthetapersshouldmatchWecanusethemaletaperthathasjustbeenturnedasatestbarBoreoutthetaperverycarefullyyouwonrsquotneedtoremovemuchmaterial before the test taper goes too far intothe finishedbore Testwitha felt tippedpenuntil youhaveaperfectfitYou can turn any taper you need this way you are not

restrictedtoMorsetapersAnothermethodmostoftenusedforlongshallowtapersistouseataperturningattachmentTheseattachments are often available as extras on higher qualitylathes They comprise a slide mounted onto the back of thelathe Often the guide is dovetailed with a sliding blockattached to the cross slide to guide the tool on a taper ThedepthofcutisusuallyputonusingthetopslidesincethecrossslideisusuallydisconnectedfromthefeedscrewInthiswayit

isfreetomoveinandoutcontrolledbytheguide

Taperturningattachment

Settingthetopslidebyclockinganexistingtaper

Anothermethodweshalllookatfortaperturningistooffsetthe tailstock on its base This will make the work turnedbetween centres become tapered either large or small at thetailstockenddependingonwhichwaythe tailstock isoffset ifsettowardsthebackofthelathethediameterwillbelargerat

the tailstock end if the tailstock is moved to the front thetailstockendwill be smaller indiameter Theamountof taperthatcanbeturnedinthismannerislimitedsincetheheadstockandtailstockcentresareoutoflineThe final method of offsetting the workpiece is by using a

boringhead inthetailstockYouneedahome-madehardenedsolidcentrethatfitswheretheboringtoolwouldnormallygo(AsmallUnimatlathesizerunningcentremightbeideal)SettheboringheadsothetooltravelishorizontalYoucanthenoffsettheboringheadcentresocreatingataperThisisthesameassetting the tailstock over but you donrsquot have to realign thetailstockafterwards

Usingthefixedsteady

USINGFIXEDANDTRAVELLINGSTEADIES

The fixedsteady isusedmainly to turn theendofabaror tocentre a workpiece that is too large to fit through the chuckObviously bar stock should not protrude from the chuckmorethan is necessary to work on This is where the fixed steadycomesinThefixedsteadycanbesettothediameterofthebarsothattheendofthebarcanbemachinedsafely

Thesteadycanbesetusingachuckmountedonthistailstockadaptor

Travellingsteady

Settingthesteadybyusingachuckmountedonanadaptor

Onewaytosetthefixedsteadytosizeistoturnabitofbarin the chuck to the same size as the barwewant to use thesteadyonThenwecanmovethefixedsteadyalongthelathebedandfittheworkpieceintothechuckandinthesteadyTheendof thebar nearest to the tailstock shouldnowbe runningtrueandcanbeworkedonsafelyThebarcanbecentredrilledfacedorotherwiseworkedonAn alternative way to set the steady is to support the

tailstockendof thebarwitha threejawchuckmounted in thetailstockAdaptors to take the threejawchuckareavailableoryoucouldmakeyourownJustsupportthebaratbothendsinthethreejawchucksandsetthesteadyfingerstothebarThe fixed steadycanalsobeused to support tubes thatdo

nothaveanymaterialinthecentreThe fingers of the steady need to be lubricated regularly

while inuseThis iseasilydonebydrillinga smallhole in thetopfingerwithacountersinkinsidetheslottotakeoilThetravellingsteady ismostoftenusedwhenturningdown

small diameterbarsor screwcutting long slenderbars It boltsonto the front of the cross slide in line with the chuck and

travelsalongwhenthecrossslideismovedalongthelathebedWhen turning the travelling steady can either be set to thediameterofthebarbeforeturningandtoleadthetooloritcanbesettothefinisheddiameterrequiredandtofollowthetoolNormallythefingersaresetto leadtheturningtoolbut if thebarisroughforexampleifitisdentedorrustyitisbetterforthefingerstotrailtheturningtoolIfscrewcuttingthetravellingsteadyshould lead the toolso that itdoesnotdeflectorwearduetoaburrbeingthrownupbythescrewcuttingtoolSteadies will not be used very often but they are

indispensableontheoccasionswhentheyareneeded

Travellingsteadywithleadingfingers

Travellingsteadywithtrailingfingers

MAKINGASIMPLEFORMTOOL

Youmay often need to produce a particular shape such as aradiusonacomponentTheeasiestmethodtodothisiswithaformtoolAsanexamplewewillmakeasimpleformtooltocutahalfcircleonabarofbrassForaradiusof3mmforexampleweneedtoproducea formtoolusinga6mmdiameterdrillorreamFormaterialwewillusegaugeplateahighcarbonsteelthatcomesintheformofagroundflatbarApieceabout5mmthick and10mmwide is needed although the size is not thatimportantaslongasthegaugeplateisthickenoughtoabsorbanyturningstressesIdeallyweneedataperedreamerthatwillproduce a 6mm diameter hole somewhere along its lengthalthough you could use a parallel 6mm reamer a slot drill orendmillorevenastandardtwistdrillDrill a hole through the gauge plate and open up to 6mm

diameterAim togetagoodsurface finishon thesidesof thehole Hacksaw and file half the hole away to leave the shaperequired on the finish turned component Now we need to

harden the tool although ifweare justdoingacomponentortwoinbrasswecouldprobablygetawaywithouthardeningitHardeningissimpleenoughheattheworkingendofthetool

toredstopheatingandletthegaugeplaterestforacoupleofminutesThiswillgive thegaugeplateachance tochange itsinternalstructureReheattoredandquenchinatubofwaterThisshouldhardenthetoolAlthoughabitbrittle itshouldbefine for making a few components Stone the top of the tooluntil thecuttingedge issharp Ifnecessaryyoucanpolishtheinside of the radius that is going to do the cutting There areseveralmethodsyoucanuse includingapieceofwetanddrypaperaroundabitofbaraverysmallgrindingwheelcalledamounted point or a bit of round bar with fine valve grindingcompoundonitWhicheveryouuseaimforapolishedfinishasthe finish on the turned component is directly related to thefinish on the form tool You canmakeall sorts of simple formtools with gauge plate a typical example being a facing toolwitha30-degreechamfertofaceandchamfernuts

CopytemplatereadytouseMetal

MachiningfromaTemplate

MachiningfromaTemplate

YoucanmachineaprofilefromasimpletemplateThetemplatecanbecutfromgaugeplatewithafileormachinedbutitdoesnot need to be hardened The template could be used tomachinea large radius suchasa smokeboxdoor Inuse thetemplateismountedonablockonthelathebedandthecrossslide is kept in contact with the template by being pushedagainstthetemplatewithaballracefixedtothecrossslideInthenextchapterwewillbelookingatdrillingandreaming

9DrillingandReaming

ThischapterexplainshowtousedrillsandreamersinthelatheTherearemanydifferenttypesofdrillsandreamersTheyareessentialtomakingcomponentsinthelatheWewilllookatthevarioustypesandhowtochoosethespeedsandfeedsforusingthem

Thisdrillchuckrequiresachuckkey

TYPESOFDRILL

Drills are normally held either in the tailstock if they have aMorsetaperor inadrillchuckiftheyhaveaparallelshankA

drillchuckismountedonaMorsetapershankthatisusuallythelargestMorsetaperthatthetailstockwilltakeThelargestsizeof drill that will normally fit a drill chuck is frac12in (13mm) indiameter although larger chucks are available at a cost Thesmallest sizeofdrill thatafrac12in (13mm)drill chuckwill take isusually about 116in (15mm) This is because the larger drillchuck is incapableofclosingdownenoughto take thesmallersizesofdrillThismeanswewillprobablyneedtwodrillchucksoneforlargerdrillsandoneforsmallerdrills

Hand-tighteningdrillchuck

TherearetwomaintypesofdrillchuckOneistightenedbyusinga chuckkeywhichhasa small bevelgearbuilt on to itthatmates with the outer sleeve of the drill chuck itself Theother type is hand tightenedwhere the outer chuck sleeve isknurledtotightenthedrillthesleeveisturnedbyhandLargerdrillsabovefrac12in(13mm)usuallyhaveaNo1orNo2

MorsetapershankYoucangetMorsetapersleevestoconvertalargeMorsetoasmallerMorsetaperYoucanalsogetasmallMorsetolargeMorsetaperconverteraswell

Drillwithataperedshank

Some larger drills are also available with parallel shanksTheyaremadewithasteppeddownfrac12inparallelshankandarecalledblacksmithrsquosdrills

Blacksmithrsquosdrill

Themostusefuldrills in theworkshopcomeassetsofhighspeedsteeljobberdrillsinacaseThemostpopularsetcovers1mmto6mm increasingby01mmstepsAnotheruseful setcoversfrom6mmto10mmalsoincreasingby01mmstepsIfyouareintomodelengineeringasetofnumberdrillsfromNo1toNo60istoberecommended

Asetofmetricdrillscovering1ndash6mm

Drills are also available in different lengths Stub drills areshorter than standard jobber drills Several lengths of longseries drills are also available ranging from one and a halftimesthelengthofajobberdrilluptoseveraltimesthelength

Differentlengthsofdrills

Mostdrillshavetwoflutesbutcoredrillsarealsotobehadwith three four or evenmore flutes As their name suggeststhese are usually used for drilling out cored holes in castings

CoredrillsarenotnormallycapableofstartinganewholebutareusedforopeningupexistingholesAstandarddrillusuallyhasanincludedangleof118degrees

Stub drills and cobalt drills often have a 135 to 140 degreeangle for use on hardermaterials such as stainless steel andaircraftsteelsBack rakeondrills is oftenground radially Another typeof

pointhoweverhasfourfacetstothepointFour-facetdrillsaremuch better at starting a hole than a standard jobber drillwhich tends towanderunless followingacentrepoporcentredrill Four-facet drills also require less pressure to drill a holesincethepointisthinnerthanastandarddrillandtheyarefareasier to sharpen accurately by hand than standard jobberdrillsDormerdoarangeoffour-facetdrillscalledA002withatitaniumnitridecoating(TiN)andafour-facetpoint

Three-flutecoredrill

DormerA002four-facetdrillpoint

To drill an accurate sized hole requires two ormore stepsfirst youdrill the hole undersize (by perhapsfrac12mm) then youfollowthroughwithasizedrillThechancesaretheseconddrillwillcutdeadtosizeasitisonlycuttingasmallamountfromthediameter Obviously if you are drilling a large hole moreintermediatestepsmayberequiredSpeedsfordrillingarethesameasthosegivenforturninginthetableinChapter3

Setofcentredrills

REAMERS

There are several types of reamers available for use inworkshops again with either Morse taper or parallel shanksSomehavesizeparallelshankstheshankbeingthesamesizeas the reamer while others are availablewith shanks smallerthanthereamedsizeThereisalsothewaistedreamerwheretheshankisthesamesizeasthereamerthemiddleissmaller(waisted)andthecuttingendistheholesizeYoucanalsogetadjustablereamerswheretheendisexpandedbytheuseofascrewinthecuttingendofthereamer

Handreamerthefrontparthasaslighttaper

Straightshankmachinereamer

Waistedshankmachinereamer

Morsetapershankmachinereamer

Parallelreamersaredividedintotwotypesparallelmachinereamerswhere thecuttingdiameter is thesameallalong theream and hand reamers where the cutting end is slightlysmallerandtapersuptothefulldiameterWhen drilling a hole for reaming it is advisable to use the

two-holemethodfordrillingYouaremore likelytogetagoodsize hole prior to reaming For small reamers up to 04in(10mm) leave about 0012in (03mm) for the reamer toremoveForreamersuptofrac34in(19mm)leave0016in(04mm)and over frac12in (13mm) leave 0020in (05mm) For reamingspeedsuseabouta third toahalfof thedrillingspeed for thesamediameterFeedsshouldbefrom0002to0004in(0025ndash005mm)per toothper revMultiply the feedper toothby thenumberofteethtogivethefeedperrevolutionItisbesttouseneatcuttingoilformostmaterialsexceptfor

aluminiumforwhichparaffinshouldbeusedandplasticwhichrequirescompressedairorplainwaterYoushouldnotuseoilasacuttinglubricantforanytypeofplasticasitcanattackandordegradetheplastic

10BoringToolsandBoringHeads

Thischaptershowsyouhowtoboreholesinthelathewiththeworkheldinachuckmountedonthefaceplateorfixedtothelathecrossslide

TypicalHSSboringbar

DIFFERENTTYPESOFBORINGBARS

BoringaholetosizeisoneofthemostexactingjobsyoucandoinalatheItisrelativelyeasytoturnashafttofitaholebutitis much harder to bore an accurate hole to fit a shaft Ifpossibleyoushouldboretheholebeforeturningtheshaft

YouarelikelytocomeacrossHSSboringbarsorinsertedtipboringbarsBothhavetheirusesTheHSStoolisidealformostgeneralhole-boringjobsbuttheinsertedtiptoolisfarsuperiorfor materials such as cast iron The boring bar should be aslargeasyoucangetintotheholewhilestillallowingswarftoberemovedTheboringbarshouldonlyprotrudefarenoughtoenableitto

go completely through the bore Any more protrusion than isnecessarymay result in chatter or a dig in in the bore Thefront clearance on the boring bar tip should be as small aspossiblewithoutrubbingasstrengthisimportantBoringcanbeusedtofinishaholetosizeorsimplytotruea

holeupafterdrillingandpriortoreaming It isbesttoruntheboringtoolthroughtheholeusingafinefeedtothecarriageifyouhave the feedoptiononyour latheThe final finishingcutshouldbeputthroughtwoorthreetimesatthesamesettingtoeliminateanyspringinthetoolworkorlatheIftheholehasanintermittentcutthroughitsuchasacrossholetheholeisbestboredtosizeIt ispossible toborequite smallholes if youhave the right

tool Commercial lsquosmall holersquo boring tools are very expensivebut Ibuythemsecond-handwhenever Iseethemso Iusuallyhave a stock It is easy if time consuming to grind up smallboringbarsbuttheyareveryusefulespeciallywhenyouneedtotrueupasmallholepriortotappingorreamingEndmillsandslotdrillsmakeusefulboringtoolsAs longas

yougetthecuttingedgeoncentreheighttheywillboreaswellasaproperboringbarespeciallyinaluminiumYoucanmakesimplehome-madeboringtoolsbydrillingand

reamingaholetotakeaHSStoolbitintoasteelshankIdeallythe shank should be made of high tensile material or silversteelThetoolbitshouldbesecuredwithahightensilesocket-headedgrub screwor similar The tool bit caneitherprotrudefromthesideoftheboringbarforthroughholesorprotrudeatthe frontof theshankat45degrees ifyouareboringablindholeRoundboringbarscaneitherbeclampedintotheVeegroove

foundinsometoolholdersorheldinasplitsquareshankEithermethodissuitableespeciallyastheshankcanbeslidinoroutofthetoolholdertominimizeprotrusionSpeciallyshapedtoolbitscanbeusedtoundercuttheendof

the borewhen it needs to be screwcut and canrsquot be cut rightthrough Inserted HSS boring bars can also be ground up forundercuttingbeforescrewcuttingThereareseveralmethodsofcheckingaboreforaccuracyIf

youhavetoboretheholetofitanexistingcomponentperhapsaballraceyoucanuse theexistingcomponentasagaugeorturnupagaugeRoughout theborewithina few thouof thefinishedsize taking twoor threespringcutsUsea telescopicgaugeapairofcalliperswithamicrometeroradigitalverniertomeasuretheholeBorethestartoftheholebynomorethanonethouata timedonotgoright throughtheboreTest thefrontoftheboreifthegaugedoesnotgointotheborerunthetool right throughunderpower feedBoreout the frontof theholebyanotherthouchecktheboreandrepeatuntilthegaugejustgoesintothestartoftheholeFinishtheboreatthesamesetting checking that the gauge just enters Take a couple ofspringcutstoensuretheboreisparallelYoushouldnowhaveanaccuratelysizedholeThe trick to boring is to finish with very fine cuts Many

engineersdonotrecommendfinecutsbutIhaveneverhadaproblemaslongasthetoolissharp

Asetoftelescopicgaugesforcheckingaboreusedinconjunctionwithamicrometer

Checkingaborewithahome-madegaugeTheleadinisonethousmallerthantheborerequired

USINGABORINGHEADINTHELATHE

AnothermethodofboringacomponentinthelatheistoboltitdowntothecrossslideWhentheworkpieceisbolteddownandtheholeposition is linedupwith theheadstock youcanboretheholeintheworkpieceinseveralwaysFirst however you might need to put a hole into the

workpiece to clear the centre of the hole out of theway Youcandothisbyusingadrillinathree-orfour-jawchuck(smallerdrillscouldbeusedinadrillchuck)Startwithasmalldrillandworkupalmosttothefinishedsizeoftheholetobebored

Boringaholereadyforreaming

Toboretheholethefirstoptionistoholdaboringbarinthethree-jaw chuck This is a good basic method of boring aworkpieceonthecrossslideTheonlyawkwardbitisadjustingtheboringbarsothatasizeholeisboredThisisusuallydonebyanadjustingscrewpressingontothebackofthetipoppositethe cutting edge The tip itself is usually clamped by a grubscrewthroughthesideoftheboringbarHoweveryoucanuseaboringbarthatisafewthouundertherequiredsizeandfinishoffwithareamerA similar way that is easier to adjust is to use the same

boringbar in the independent four-jawchuckThen insteadofadjusting the tip in the boring bar you can adjust the entireboringbar inthefour-jawchuckThisasyoucanimaginewillbealoteasierthantryingtoadjustthetipintheboringbarThethirdmethodofboringworkonthecrossslideistousea

properboringheadThis iseasy toadjustas it isdesigned forthisverypurposeFinallyyoucouldusea lsquobetweencentresrsquoboringbarwhich

isheldbetweentheheadstockandtailstockcentresThisistheonly option when you are doing a long bore such as a largecylindercastingforalocomotiveortractionengine

Boringtheholeusingthefour-jawchuckmethod

Usingtheboringheadinthelathemandrel

Unlike when you are facing and boring a component in achuck you will not be able to face across the front of thecomponent (Boring heads with the ability to face across theworkareavailablebutareunlikelytobefoundintheamateurrsquosworkshop) Thismeans you will have to face across the workwith a flycutter in order to keep the face true with the boreFlycutters are available quite cheaply or you couldmake yourownandholditinthefour-jawchuck

Aflycuttersuitableforfacingthefrontofacomponentthathaspreviouslybeenboredonthe

crossslide

11KnurlingRadiusTurningandProductionMethods

This chapter explains how to use knurling tools and radiusturningtoolsaswellasusingbasicproductionmethods

KNURLING

Knurlingistheprocessofformingorimpressingapatternonapiece of metal often for the purpose of making a grip for apieceofequipmentsuchasaknobBothstraightanddiamondknurlscanbeproduceddependingonthetypeofknurlyouareusing Diamond knurling is usually done with two knurlingwheelsalthoughsingle-wheeldiamondknurlsareavailableKnurls are also available in fine medium and coarse sizes

although the size is relative fromdifferentmakers The speedfor knurling is usually about half of the turning speed for thesame diameter bar Normal knurling is of the male patternwheretheknurlingconsistsofraisedpyramidsFemaleknurlingismuchrarerandconsistsofdepressedpyramidsThere are threemain types of knurling tool but only two of

these are found in the average workshop The first type ofknurling tool is the so-called lsquocutrsquo knurling toolwhichactuallycutsaknurlratherthanpressestheknurlintotheworkThisisaspecialized tool more often used in industry and is veryexpensivesoitisnotfoundinmanyhomeworkshops

lsquoBumprsquoKnurling

The most common knurl is the single-or double-wheel knurlsometimes called a lsquobumprsquo knurling tool The wheels aremountedat the frontof the tool This typeof knurl is pressedintotheworkbyusingthecrossslideandcanproduceagoodqualityknurlHowever itdoesputveryheavypressureonthemandrelandlathebearings

Acommerciallyavailablestraddleknurlingtool

StraddleKnurling

Thebest typeofknurl foroccasionaluse is thestraddleknurlwhich has two knurling wheels that completely straddle theworkpieceThistypeofknurldoesnotputastrainonthelathebearings and so is preferred bymost lathe users (Two-wheelknurlingtoolsareavailablethatresemblestraddleknurlingtoolsbut they donrsquot open up to take anything more than smalldiameters relying on pressure at the side of the job like alsquobumprsquoknurl)To set the straddle knurl up wind the tool against a bit of

plateheldontothesideofthebarRemovetheplateandmovethetoolinbythethicknessoftheplatehalftheknurldiameterandhalfthebardiameterThiswillputthetoolontothecentrelineofthebar

Settingtheknurlingtool

In use set the knurling wheels to the centre as describedabove wind the knurls onto the outside diameter of the barwindtheknurlawayfromthebarandmovetheknurlingwheelsclosertogetherbytwicethedepthoftheknurlpatternSwitchthelatheonandwindthetoolbackontothecentrelineandthetool should start to form the knurl You can now traverse theknurlingtoolalongtheworkpieceto formtheknurl remembertousecuttingoilNote that theknurlsshouldhavechamferedsidesifyouaretraversingalongtheworkpieceYouneedtogodeepenoughsotheknurlisfullyformedbut

notsodeepastodeformtheknurlBecausetheknurlstraddlestheworktheknurlsstartoff independentlyandmaynotbe inalignment around the diameter Once you start moving theknurlingtoolbackwardsandforwardsalongtheworkhoweverthetoolshouldlineitselfupThismeansyoumayhavetoturndownorpartoffthebarwhereyoustartedtheknurlIfyougotoodeepespeciallyinaluminiumthewholedepth

ofknurlcouldgetdestroyedandevendropoff theparentbarThis is called flakingKnurling isnotadifficultprocessa littlepracticewillsoonhaveyouknurlinglikeaprofessionalengineer

Anaccomplishedbitofknurling

AformtoolcuttingaballTheinsetviewshowstheformtoolandafinishedball

RADIUSTURNING

Sometimesweneedtoformanexternalradiusontheendofabit of bar perhaps for a ball-shaped handle We can use asimple lathe attachment to do this Basically the attachment

consists of a short turning tool mounted onto a U-shapedcomponent that is arranged to pivot on another U-shapedcomponentheldinthelathetoolpostBy pivoting the attachment back and forth a radiuswill be

generatedForatrueradiusthepivotpointshouldbesetonthecentrelineofthebarTheradiusgeneratedwilldependonhowfarthetoolbitissetbackfromthecentrelineoftheworkpieceTosetthetoolupwindtheattachmentuptoaplateheldto

the sideof thebar youareworkingon remove theplate andwindinthewidthoftheplatehalfthewidthofthebarandthewidthofthefixturetothecentrelineofthepinThiswillputthepivotonthecentrelineThenyoucansetthetooltotheoutsidediameterofthebarThiswillproduceaballthesamediameterasthebarTo turnan internaldiameteruse the samemethodbut the

turning tool will need to pass through the centre of the pivotand out the other side You will be limited to shallowdepressionsratherthanlargesemicirclesbutthistechniquecanstillbeusefulonoccasionThealternativemethodof formingaball iswithaball form

tool

Astopbarblockforthecarriagestop

PRODUCTIONMETHODS

PRODUCTIONMETHODS

Foreaseofproductionthefirstthingyouneedtouseisabedstop (see Chapter 5) The chances are that you will need tomakeyourownTheoneIuseisveryversatileandconsistsofablockmountedatthefrontofthelatheheadstocktogetherwitharodtoactasthestopDependinguponwhatyouaredoingitmaybeusefultohave

morethanonestopbareachwithitsownseparatestopblockInusethebarisinsertedintothemainblockasfarasthestopblock(if fitted)andlockedinplaceThefirststopbarcouldbeusedto facetheworkpieceandthesecond(shorterbar)couldbe used to turn along the diameter while a third bar couldpositionthepartingofftoolAnalternativeadditiontothestopbarcouldbeawasher(orwashers)ofknownthicknessplacingthewasher(orwashers)onthebarwillextendthestoppositionbythethicknessofthewashersusedAusefultipistostampanumberonthestopblockssothat

eachone isnumberedYoucouldalso stamp the thicknessonthewasherssoyoudonrsquothavetokeepmeasuringthemandjustpickthemupinthecorrectorderItsavesalittletimeandhelpsavoiderrorsThe whole point about using a stop is the consistency of

positionwhichistransferredtotheaccuracyofthecomponentit gives Once you have learnt to use a stop youwill wonderhowyoumanagedwithoutitEvenforone-offcomponentsitwillsaveyoutimeForatypicalone-offsteppedshaftsetthestopsotheturning

tooljustfacesthebarandfaceoffMove the top slide along for the length of the turned step

requiredTurnthestepYounowhaveastepontheendofthebarofaknownlengthNofiddlingnomeasuringndashyouknowitiscorrectUsing the bed stop offers a simple way of doing repeat

turning of lengths and diameters in the lathe Stops are notlimited to production methods they are very useful formachiningone-offsaswell

A single stop bar will serve for much of the work you aredoingbutsometimesyouneedmorethanonestopTheanswerhereistousemorethanonestopbarinconjunctionwithastopblockEachbarhasitsownstopblockthatcanbetightenedupThenyoucaninterchangethestopbarsandeachbarcanbesettotherequiredlengthbyusingavernierorruleYoujustsetthetwostopblockstothedifferencerequiredandlockthestopbarintheholderasnormalWhenyouneedmorethanoneofeachitemitisveryeasyto

save time in theworkshop once the lathe is set up you canmake several items in quick succession A typical example ofthis type of production is a simple spacer Set a facing andchamferingtoolinonetoolholderapartingofftoolinanothertoolholderandadrillinthetailstockchuckThefacingtoolandparting off tool are in fixed positions to each other so it is asimplematter of drilling thehole facingoffwithone tool andparting off with the other As long as the gap between thepartingofftoolandthefacingtoolremainsconstantthespacerswill remain at the samewidth each time youmachine one ofthemTheeasywaytosetthethicknessofthewasheristofaceoff

theendofthebarbringthepartingofftooluptothefinishedface and lock the cross slide Wind the parting off tool backslightly so you can move the bar forward in the chuckMeasuring with the vernier calliperrsquos depth rod from therighthandfaceofthepartingofftoolbringthebaroutslightlylonger than is needed for the washer thickness Using thetailstock chuck drill the hole using a centre drill for the firstwashertoensurethedrill runstrueNowsetthefacingtool inpositionfaceoffthewasherandpartofffromthebarMeasurethe washer and adjust the facing tool either way so that thethicknessof thewasher iscorrectPull thebar fromthechuckslightlyfurtherthanthefacingtoolsothateachwashercanbefaced to lengthYoucanmakeasmanywashersasyouneedall of the same thickness The same applies to nuts and anyothercomponentthatneedstobeasetlengthIfmakingboltsor screws theprinciple is thesamebutyou

willneed to turndown thediameter tobe threadedThis timethedifferencebetweenthepartingofftoolandtheturningtoolisthethicknessoftheheadInordertofacetolengthhoweverawasher of a known sizemust be inserted between the stopblockandthecrossslideThiswasherwillbethelengthoftheturneddownportionofthecomponentIfyouwanttomakeabatchofcomponentsbutdonrsquotwantto

keepmovingorchangingtoolsyoucanmachinethebatchonestepata timedoingoneoperationoneachcomponentbeforedoing the next operation on all the components Repeat thisuntil the complete batch ends up as completed componentsYou have the added advantage that the components willprobablyallbethesameshapeandsizesomethingthatisnotalwayspossiblewhenmachiningeachcomponentindividuallyTo make a batch of components such as washers to the

samethicknessisquitesimpleSetupapartingtooltopartoffthe components and set up a facing tool to face thecomponentsThedifferenceinpositionbetweenthefacingtooland the parting toolwill be the thickness of thewashers Youcanadjustthethicknessofthewasherbymovingthefacingtoolbackwardsor forwardswith the topslide toadjust it The rearpartingofftooldoesnotmoveotherthantopartoffthewasher

Makingwasherstothesamelengthusingfixedpositiontools

TAILSTOCKTURRET

AnotherusefulaccessoryisthetailstockturretThisisarotatingheadthatisusuallysetbackatanangleItfitsintothetailstockof the lathe and has multiple stations to take different toolsoftenitwilltakefourfiveorsixtoolsThebenefitofthisisthatitcanhaveabarendstopacentredrilladrillacountersinkatapandadieoranycombinationthereofallsetupreadytousein sequence The tools normally fit into holes bored into theturretToavoidtoolsstickingouttoofar it isbesttousestubdrillsinsertedintoroundbarsthatfitintotheturret

Anindexingturretthatfitsdirectlyintothetailstockofthelathe

YoucaneitherdrillandtaptheroundbarsoruseLoctite tosecure the drill in the round bar You can also buy roundadaptorswithaJacobschucktapermachinedontheendtotakechucksAnothermethodoffittingchucksistodrillandtaptheround bar to take chucks with threaded extensions ThesechuckscanoftenberetrievedfrombrokenBlackampDeckertypedrillsDieholderscanslideonapieceofroundrodintheturretFor

smaller diameter threads you can stop the die from rotatingusing your hand There is no need to reverse the lathe whenthreading just stop it and spin the die off by hand the samegoes for taps For larger taps and dies you can use a shorttommybartostoprotationbutmakesurethatthetommybarpositionisclosertotheworkthantheendofanyofthedrillsorthetommybarwillsnapthedrillsifyouletgoofitorifthetapordiejamsupYoucanalsomakeorbuyarunningcentretofitintotheturrettosaveremovingitwhenyouneedtousealathecentreOnlydothiswithsmallorlightworknotheavybarsorfor largecutsWhenused inconjunctionwithagoodbedstop

system a tailstock turret becomes a very versatile productionfacilityTheturretcanbemademoreversatilebyfittingalever-feed

tailstockattachmentoracapstan-style feedattachmenttothetailstockturretEitheroftheseattachmentswillmaketheturretveryfastinoperation

Anindexingturretsetupwithastopandacentredrill

Standardlever-feedtailstock

SECONDOPERATIONWORK

SECONDOPERATIONWORK

Sometimes it is necessary to do second operation work on apart-machinedcomponentUsually thiswillbeon theoppositeend to the one already turned There are two main ways ofholding theworkpiece in the correct position for furtherworkthechuckbackstopandsoftchuckjawsThechuckbackstopisquitesimpletomakeItconsistsofa

draw-incolletapieceofplainbarforthestopabitofthreadedbar a nut and a top hat collar The collet goes into the lathemandrelandisdrawninbythethreadedbarThethreadedbargoesthroughthemandrelandislockedinplacebythenutandthe tophatcollarat the left-handendThe tophatcollar is toprotecttheendofthemandrelThestopbarfitsthecolletandispositionedsothattheworkislocatedattherightdepthinthechuckThismeansthateachcomponentput intothechuckupagainstthebackstopwillalwaysbeheldinthesameposition

Capstan-stylelever-feedtailstock

Adraw-inbackstop

Softjawswithhexagonsadded

The secondmethod is to hold the component in soft jawswhich are bored out to hold the component (see Chapter 5)ThismeansthecomponentshouldrundeadtrueandeachonewillbeheldinthesamepositionreadytobemachinedSoft jaws tend to be used for larger components while the

backstop ismore likely tobeused forbarworkYoucanboltextension pieces to soft jaws to hold larger diameters orextensions can be machined to make a nest to take largercomponentsWhensoft jawsarewornoutandfaceddowntoo

lowforfurtheruseyoucanboltapieceofhexagonbartoeachjawtogivethemanewleaseoflifeIfyouhaveabatchofthreadedcomponentstofinishonthe

second end you can screw them into a bit of bar held in thechuck If theyarehexagonbolts just tightenup lightlywithaspanneriftheyareroundheadandtheheadwillbemachinedlateryoucouldtightenanduntightenthemwithapairofpliersThe more production work you do the more varied the

methods you will learn and the quicker you will makecomponentstoahighstandardofaccuracyA sensitive drilling attachment can be very useful when

drillingwith tiny drills The feed is by hand which gives it itssensitivity The attachment can also be used for small tapswherethetravelisfairlyshort

Machiningscrewheadsbyholdingthescrewinathreadedmandrel

Asensitivedrillingattachmentthatfitsintothe

tailstockchuck

ThisVeeattachmentisusedforcrossdrillingandcanbeusedintheheadstockorthetailstockofthelathedependingonthelengthofthebartobecrossdrilled

ThisisarevolvingtaperforthetailstockIfyoufitadrillchucktoityoucanuseitasarunningsupportforsmallbarwhereacentreisnotpermissible

12TapsDiesandScrewcutting

Thischaptershowshowtousetapsanddiestocutinternalandexternal threads in the lathe Italsoexplainshowyoucansetupasimplegeartrainandcutascrewthreadwiththehelpofascrewcuttingdialindicator

Atypicaldie

CUTTINGTHREADS

Threadcuttingeither internalorexternal isan importantpartoflearningtousealatheThepurposeofathreadisusuallysothatyouareabletoholdpartstogetheralthoughotherusesforthreadssuchasleadscrewsandfeedscrewsformachinetoolsareoftencalledfor

Safetyhasalreadybeencoveredindepth(seeChapter2)butafewextrawordsonsafetywhenthreadcuttingarecalledforWhen tapping a hole or threading a bar from the tailstock atailstocktapordieholderisoftenusedForthesmallerthreadstheholdershaveaknurledbodyandrotationcanbestoppedbysimplyholdingthebodyoftheholderinyourhandAslongasyoukeepyourhandawayfromthechuckandany

sharp lathe tools on the cross slide you should be fine (ifpossible remove either the tool holder or the tool itself )Providedthereisnothingtocatchorsquashyourhandonyoucan hold the knurled tap or die holder in your handwhile thelathe is running slowly under power and releasing the holderwhen the full length of the thread is cut or the pressurebecomes too great for you to stop the rotation (By slowly Imeaninveryslowbackgear)For largerthreadshoweveratommybarwilloftenneedto

beusedtostopthetapordieholderfromrotatingWhenusingthe tommy bar to prevent rotation do not under anycircumstances use the lathe under power Instead switch themachinerightoffandunplugit ifpossibleTurnthetapordieholdingthetommybarwiththerighthandandstopthechuckfromrotatingwiththelefthandThere are already many published charts providing thread

data covering such factors as tapping hole sizes minimummaximum and effective diameters as well as pitches andthreadsperinchIwillnotbeprovidingthemherebutwishtopoint out that tapping size drills can vary with the materialbeingcutWhenIamtappingsmallsizes instainlesssteel forexampleIusuallydrillthehole0004in(01mm)largerthanthefigurestated in thechartThisway Iam less likely tobreakatapinthehole

HSSorCarbonSteel

TapsanddiesareusuallymadefromcarbonsteelorHSSHSStapsanddiestendtoremainsharpformuchlongerthancarbonsteeltapsbutcarbonsteelisusuallycheaperNewcarbonsteel

tapsanddieswillprobablybefineforsmallerholesandsoftermaterials but wherever possible HSS should be your firstchoice Second-hand taps and dies are sometimes availablefromtoolshopsoroneBaybutinmyexperiencetheyareoftenbluntandnotworthbotheringwith

Lubricants

Whether tapping threading with a die or screwcutting it isnormallyessentialtousealubricantevenonbrassForbrassaluminium and bronze kerosene (paraffin) or white spirit isgenerallyusedandcanwithadvantagehaveasmallamountofcuttingoiladdedFor steel and stainless steel amodernpaste-based tapping

compound or cutting oil should be used This can also beappliedtocopperthismetalcanbestickybuttakeiteasyandall should gowell I also use paste or cutting oil on cast ironAlthoughmostrecommendationsaretocutcastirondryIhavefoundalubricanttobeveryhelpful

Screwthreadpitchgauge

ThreadGauges

When following a published design you will probably use thethread sizes as recommended by the designer If you are

making a thread to match an existing thread however youneedtofigureoutwhattheexistingthreadisThisiseasiesttodoonanexternalthreadIfyouhaveonlythenuttrytofindaboltthatwillfititandusethattocheckthethreadIfyoucanrsquotfindamatchingboltandtheholeinthenutisbigenoughyoucouldtrypressingabitofplasticineintotheinternalthreadandmeasuringthatTomeasuretheexternalthreadweneedtodeterminethree

thingsusingathreadpitchgauge theoutsidediameterof thethread the pitch of the thread and the thread angle Thesethree checks will probably be sufficient to decide what thethreadactuallyisBritish threads such as British Standard Fine and British

Standard Whitworth and also the Model Engineer threadsystemhaveanangleof55degreesAmerican threads such as UNF (Unified Fine) UNC (Unified

Coarse) UNEF (Unified Extra Fine) ANF (American NationalFine)ANC(AmericanNationalCoarse)are60degreesasisISOmetricUnusually theBritishStandardCycle thread is also60degreesThe other thread youmight come across is the BA (British

Association)threadThishasathreadangleof47frac12degreesandismetricbasedThelargestBAthreadis0BAwhichhasa6mmdiameterwith a 1mmpitch TheBA series godown to 22BAbutinpracticeyouareunlikelytocomeacrossanythingsmallerthanabout14BA

TAPS

TappingistheprocessofcuttinganinternalthreadwithatapFirst a hole is centre drilled and drilled in the workpiece Irecommend that you give the top of the hole a 90-degreecountersinktogivealead-intothetapandalsotostopthetapfromthrowingupaburrontothefaceofthework

Setofhandtaps

TypesofTap

The many types of tap can be divided into hand taps andmachinetapsHandtapsarenormallyheldinatapwrenchbutcan be held in the lathersquos tailstock chuck or a purpose-madetailstocktapholder

Close-upofahandsecondtap

WhentappingbyhandstartthetapuntilitstartstobiteandgiveitanextraturnorsoReversethedirectionofthetapforaturn to break the chip Continue forward for a couple of turnsand then reverseasbeforeContinue todepthor through theworkpiece by continually tapping a couple of turns reversingandcontinuingforwardThisshouldclearthechipsandpreventthetapfrombreakingIfthetapgetshardtoturntakeitrightoutoftheholetoclearanyswarfaddsomemorelubricantandcontinuetappingA set of hand taps will normally comprise a taper tap a

secondtapandaplugtapUsuallyyouwillstartaholewithataper tap This is a tap where the outside of the thread isreducedtowardsthepointbygrindingitonataperThistypeoftap can be used to start the hole but if the hole goes rightthrough the work it may be possible to screw the tap rightthroughtheholesoformingafullthreadrightthroughIfthetapertapistooshortorifyouaretappingablindhole

youneedtofollowthetapertapwiththesecondtapwhichhasmuch lessofa taper In fact itonlytapersrightat thestartofthetapTheplugtapisfinallyusedusuallytofinishoffablindhole

Theplugtaphasnotaperonitjustashortlead-inontheendBetween the three you should be able to tap themajority ofholesintheworkshopWhentappingblindholesitisbesttoworkoutthedepthand

fromtherethenumberofturnsneededforthetaptoreachthebottomoftheholeAsanexamplesaytheholeis9mmdeeptothepointThe tapenters2mminto theholebeforestarting tocutSo9mmless2mmgives7mmThepitchofthetapis05mm7mmdividedby05equals14sothenumberofturnstothebottomoftheholeis14Inpractice12or13turnswillbethemaximumneededWhen tapping blind holes make sure that all swarf is

removedfromthebottomoftheholebeforestartingtotap

Selectionoftapholders

HoldingTaps

TherearetwomaintypesoftapwrenchthehandtapwrenchwhichisdesignedtobeheldwithbothhandsandtheTeetypetapwrenchwhichoncestartedcanoftenbeusedone-handedTapsusuallyhaveeitheracentreholedrilledintheshankor

theshankisgroundtoapointThismeanswecansupportthetapfromthetailstockeitherbyusingalathecentreorbyabitofbarinthetailstockchuckwithafemalecentreinitTeetypetapwrenchesoftenhaveafemalecentreintheendandcanbesupported on a running centreWhen the tap is supported bythe tailstock at one end and the hole in theworkpiece at the

otheritmustbeinlinewiththeholeintheworkpiece

Machinetap

MachineTaps

Themaintwotypesofmachinetaparethespiralpointandthespiral flute The spiral point pushes swarf downwards throughthe hole while the spiral flute pulls the swarf out of the holeSpiralflutetapsaremuchweakerthanspiralpointtapsandintheory should not be used for tapping by hand However inpractice you can often get away with hand tapping using aspiralpointtapifyouareverycarefulIneithercasethetapisdesigned for continuous rotation swarf being automaticallycleared so the regular reversal as with a hand tap is notnecessaryIf you are careful you can probably get away with using a

hand tap under power but only do this with a hand-held tapholderwhereyoucanquicklyletgoifthetapstartstostickYou can also getmachine taps thatwill cut a thread under

powerbyscrewingthroughthejobwithoutstopping

Spiralflutetap

SpeedsforTapping

Tappingspeedsshouldbe low lowbackgearspeedshouldbefineWhenyouhavetappedtheholetodepthorrightthroughtheworkpiecestopthelatheandspinthetapoutbyhandThiswillbequickerthanreversingthelathe

ThreadingfromtheTailstock

For small taps you can use the sensitive drilling attachment(seeChapter11)orifthetapislargeryoucoulduseaslidingtapholderThiscanbeassimpleasachuckmountedonataperat one endwith a parallel hole through the chuck shank ThechuckthenslidesonabarheldinthemaintailstockchuckForlargetapsyoucanuseatommybartostopthetapholderfromturningbutthetommybarshouldnotbesolongastofoulthelathebedoranyotherpartofthemachineifyouhavetoletgoInfactitisfarsaferifyoudonotusethetommybartothreadunderpower

DIES

Dies also come in carbon steel andHSS versions The outsidediameterofadieoftenvarieswiththesizeofthethreadbeingcutalthoughthediameterwillbetooneofasetstandardDiesusually have themakerrsquos name and the thread details on thefrontof thedieThis is theside that ispresented to theworkThediewill havea short lead-in if this isnot requiredon thefinishedthreadyoucanreversethedieanditwillcleanuptoashoulder

SlidingtapholderSlidingdieholdersarealsoavailable

When cutting a thread especially a small one it pays tomaketheinitiallengthofthreadlongerthanthatrequiredThisissoyouhaveabitat thefronttoplaywithtogetthethreadright Then you can part off the excess length leaving a goodthreadoftherequiredlengthDies are usually split so you can adjust them to cut a size

threadIdeallyyoushouldhaveadieholderforeachdiesoyoucansetthedietocutsizewithouthavingtoresetiteverytimeyouchangethedieThedieshouldbesetsothatitcutsasizethreadinonepassDie nuts are often hexagonal in shape They are used to

cleanupanexistingthreadthat isdamagednot tocutanewthreadfromscratchFor each thread you are going to cut you should make a

home-madegaugetappedwithyourowntapWhenyoucutthethreadanditfitsthisgaugeyoushouldthenhaveagoodbutnottightorloosethreadYoushoulduseatailstockdieholderwithaslidingbodywhen

threadingfromthetailstockasthiswillholdthedietruetothethreadIdeally the tailstock die holder should be knurled and also

haveatommybarholeforeaseofuseThe speed for threading with a die in the lathe should be

quitelowamaximumof60rpmshouldbefineformostjobs

SCREWCUTTINGATHREAD

Whilecuttingathreadwithtapsanddiesisperfectlyadequatefor most applications the ability to cut an accurate screwthreadbyusingthelatheisaveryusefulfacilitytohaveIfthethread is large or non-standard taps and dies may not beavailable or they may be so expensive as to be out of thequestionforuseintheamateurrsquosworkshopVariouspitchesofthreadcanbecutbythesimpleexpedient

of changing the configuration of the change gears or alteringtheleversonthescrewcuttinggearboxifoneisfittedWewillconcentrate on a lathe with change gears if you have ascrewcutting gearbox please refer to the manufacturerrsquoshandbookMost lathes that youwill comeacross are likely to have an

imperialpitch leadscrewThiswillbeapitchofsomany teethper inch (TPI) Typically this will be 4 or 8 TPI although otherpitchesareavailableForourexamplewewillbeusingalathewithan8TPI leadscrewandasetofchangewheelscomprisingthefollowingnumbersofteeth2times202530353840455055606570and75

SETTINGUPTHECHANGEGEARS

Letrsquostakeatypicalthreadpitchof20TPIForeveryturnofthemandrel the leadscrew needs to move forward 120in Thismeans we have to set the change gears so the mandrel toleadscrewturnratio iscorrect Inpracticethemandrelgear islikely tobe20 teethand this is unlikely to change nomatterwhat thread we are cutting This means we will change theleadscrew gear which has to have the correct ratio to themandrelTheTPIwewishtocutis20usingaleadscrewwithapitchof

8TPI20dividedby8givesusaratioof251Thismeansthatthe mandrel gear needs to rotate at 25 times the leadscrewgearAsthemandrelhas20teeththeleadscrewgearneedstobe25times20teethwhichisa50toothgearInpracticea20toothgearanda50toothgearmaybetoosmalltotransferthedrive from the mandrel to the leadscrew and intermediategear(s)willneedtobeusedThese gears are called idler gears and they can have any

number of teeth Youmay think these idler gears change theratio of the mandrel to the leadscrew but they do not Theysimply transfer the drive from the mandrel gear to theleadscrew and the ratio stays the same This concept can behardtograspsoIwilltrytoexplainitsimplySay the mandrel gear does one turn This makes the idler

gearorgearsmoveexactly20teethandthisinturnmovestheleadscrewgearexactly20teethAsyoucanseetheratiodoesnotaltertheleadscrewgearmoves20teethforevery20teeththemandrelgearmovesandtheratiostaysthesameThistypeofset-upisknownasasimplegeartrain

Simplegeartrain

Compoundgeartrain

Letuslookatanothercommonthreadpitch32TPITheratioofleadscrewtoTPIis41(8times4=32)Sotheleadscrewgearneeds to be themandrel gear 20 teeth times 4 = 80 teethLookingattheavailablegearswedonrsquothavean80toothgearThismeanswewillhavetouseadifferentmethodtogetour41ratioWithamandrelgearof20teethwecouldusea40toothto

give us a ratio of 21 We are now halfway there but needanotherpairofgearswitha21ratioWedohavea30anda60

toothgearsothiswouldgiveusoursecond21ratioWecouldnot set these gears up as in the previous example howeversince the two intermediate gears would just act as idlers andtheratiowouldbe2150percentoutfromwhatisrequiredWhatwewouldhavetodoismountthe40toothandthe30

tooth gears on the same spindle so they rotate at the samespeedaseachother(The20toothgearmustdrivethe40toothgearandthe30toothgearmustdrivethe60toothgearinthisorder)Thiswouldgiveusthecorrect41ratiothatweneedAswehavemountedtwogearsononespindlethisisknownasasinglecompoundgeartrainDependingonyourlatheyoumayneedanidlergearbetweenthe30toothgearandthe60toothgearAgainthiswillnotalterthegearratiosYou can also have double compoundgear trainswhere two

lots of gears are mounted together on two spindles This istaking us into complicated territory however and I will referreaders to the screwcutting chart provided for their particularlathe Ifyour lathedoesnotcomewithascrewcuttingchartasearchon the Internet should findone that you candownloadandprintoutThemost likely application of double compound gear trains

would be to cutmetric threads with an imperial leadscrew orimperialthreadsover60TPII have tried to keep this explanation of setting up

screwcutting gears simple and the maths to a minimum Theexplanationgiventogetherwiththescrewcuttingchartforyourlatheshouldbemorethansufficienttogetyougoing

ExternalscrewthreadtoolmadefromaCoventry

diechaser

CUTTINGTHETHREAD

The speed for screwcutting should be about mid-back gear ifyouhaveitpreferablysomewherearound30ndash40rpmatmostTherearetwomainmethodsofscrewcuttinginthelatheThe

firstoneinvolvesthetopslidesetparalleltotheworkandintheothermethodthetopslideissetonanangletothework

Externalsinglepointscrewthreadtoolsettinggauge

Cuttinga20TPIThreadwiththeTopSlideParallel

For a 20 TPI Whitworth thread the pitch is 0050in and thethreaddepthisaconstant064ofthepitchsothethreaddepthis 0050 times 064 = 0032in This is the depth the cross slideshouldbewoundinWhilethedepthofthreadis0032inyoualsoneedtomove

the top slide forwardat eachpass Fora standardVee threadthisneedstobehalfthein-feedofthescrewcuttingtoolsoyoumovethecrossslideinby0010inandmovethetopslidealongbyhalfthis0005in

Cuttingascrewthreadwiththetopslidesetparalleltothelathe

Cuttingascrewthreadwiththetopslidesetatanangletothelathe

Theendresulta20TPIfinishedthreadbeforetidyinguptheendandundercutting

Cuttinga20TPIThreadwiththeTopSlideatanAngle

This angle will vary according to the thread being cut but itshouldbeabout1degree less thanhalf the includedangleofthethreadforaWhitworththreadof55degreesforexampletheangleshouldbehalfof55degreesminus1degreegiving265degreesNotethattheangleistakenwiththetopslidesetat90degreestotheworkWiththetopslidehandlefacingyou(at90degreestohowit isnormallyused)rotatethetopslidethe required number of degrees (265) to the right Beginnersoften rotate the top slide 265 degrees to the left from thenormalpositionwhichwouldgivean included threadangleof127degreesThisisclearlywrongBecausethetopslideissetonanangleyouwillneedtofeed

thetopslideinfurtherthanifthetopslideissetparalleltothelatheYoucan findthe increaseddepthof threadbyusingthefollowingformula

c=bcosineofA

whereAistheanglecalculatedathalftheincludedthreadangleminus1degreegiving265degreesb is thedepthof thread(forWhitworththreadsthisis064timesthepitch)andcisthecalculatedangulardepthofthreadFor a 20 TPIWhitworth thread the pitch is 0050in and the

threaddepthisaconstant064ofthepitchsothethreaddepthis0050times064=0032inThecompensateddepthofthreadisthen0032individedbythecosineof265degrees=00357

UsingtheThreadCuttingIndicator

With an 8 TPI leadscrew if the thread being cut has an evennumber of threads the leadscrew can be engaged at anypositionof the threadcuttingdial indicator If the thread isanoddnumberyoushouldusethesamenumberoranyalternatenumberthatisoneorthreetwoorfourForthreadswithahalfpitch always use the same number For metric threads orpeculiar numbers do not disengage the clasp nuts withdrawthescrewcuttingtoolandreversethemotoruntilthetoolgoesback to the start If the thread is an exact multiple of theleadscrewtheclaspnutscanbeengagedatanypositionIfindoubtalwaysengageatthesamenumberoneIttakes

verylittletimetotraversetheextradistancerequiredFor leadscrews other than 8 TPI please refer to your lathe

manual

AcknowledgementsandUsefulContacts

I would like to thankMy TimeMedia Ltd (Publishers ofModelEngineer and Model Engineersrsquo Workshop) Ken Wilson TonyJeffreeandTranswavePowerCapacitorsLtdfortheuseoftheirphotographs

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