2f refurbishing - upper tension mechanism 2

The principals of thread tensionhave already been covered in thesection on How a SewingMachine Works page [1] E - 4.

(1) The majority of tensionadjustments for changes inthread and fabric thickness orstitch length are made throughthe upper tension mechanism.

(2) Once set, the lower bobbintension should not need to bealtered for normal operations.

How you set the tension correctlyis something we discuss insection [2] J when we look atperforming a sewing test. Herewe deal with refurbishment only.

There are basically only two typesof tension mechanisms. However,because they have constantlyimproved over the 100 years orso, there are now variations foreach model.

We start this section by explain-ing these two types, and thencover the work involved - modelby model starting with the 66/99.

For the 15K turn to page [2] F - 8and for the 201 see page [2] F - 10

Early Type (66 & 99)

To avoid snapping the threadas it is pulled tight at the end ofthe stitch formation ( see page[1] E - 2) it is passed throughthe thread take up spring (A)which takes-up' or cushionsthe strain.

The tension stud (B) has a holedrilled through it endwise, sothe tension release pin (C), canslide within it.

The thread passes between thetension discs (D & E). Thesediscs are pressed together bythe tension release disc (F) aspressure is exerted on it by thebeehive shaped spring (G).

The amount of pressure isregulated by turning theknurled thumbnut (H).

When the presser bar lever islifted, the release pin is madeto slide through the stud untilthe end of the pin pressesagainst the cross-piece bar inthe centre of the washer (F).

This relieves the pressure onthe spring. See the diagram onpage [1] E - 4.

UPPER TENSION MECHANISM - (66 & 99 models)

[2] F - 1

1

(A)

(B)

(C)

(D)

(E)

(F)

(G)

(H)

2.3.2006

22

Bobbinthread

tensionscrew 2

Later Dial Type (66 & 99)

(C) (B) (A) (D) (E) (F) (G) [I] [J] (H)

Two new components have been added;a stop washer [I] and a dial [J].

The stop washer has a protruding tail which makescontact with a ridge inside the dial preventing it frommaking more than one revolution - so the thumbnut (H)cannot be screwed off the stud or tightened excessively.

The thumbnut (H) now has a pin on the back face whichfits into one of the holes in a circular pattern on thetension dial (J). This means that the dial revolves withthe thumbnut as it is screwed in or out.

The tension release disc (F) haschanged in shape. It now houses thespring (G) and has a guide on top asa visual aid to tension setting.

(3) This picture shows the take upspring and tension stud which isused with the 66/99 simpletension mechanism.

(4) Remove thumbnut and takeoff the components down tothe tension discs.

(5) Clean or replace the discs if they are rusty or grooved.

Next check the condition of thestud. Sometimes the two prongedarms have been splayed by carelessuse of a screwdriver which makesthe thumbnut difficult to turn.

(6) Use pliers on the end of the arms (just before the thread starts) to gently bend themback to a parallel position.

(7) ...or, lever gently with ascrewdriver if the arms have been pinched together.

(8) Check the condition of thetake up spring.

This delicate part is easily damaged- if it has little resistance, or isbroken or bent, then it must bereplaced.

(9) First screw the thumbnutback on the stud a few turnsand then use a screwdriverto undo the stud and removethe stud and spring.

(10) At this stage, check that therecessed shoulders of thetension mechanism housingare in the clock handsposition equivalent toaround 25 minutes to 11.

Adjust if required - by firstreleasing the grub screw underthe arm and then rotating thetension mechanism housing tothe required position.

(11) On the early 66 and 99models the end of the take-upspring is held tight between theshoulder of the tension stud andthe mechanism housing whenthe stud is screwed fully home.

(12) Fit the new spring on thetension stud. Hold the springat about 2 oclock while youscrew the tension stud tight.

[2] F - 2


9

11

10

8

5

4

6

3

7

Early Type (66 & 99)

2.3.2006

2 2

(13) When the stud is tight, make sure the tension spring isstill at 2 0clock, then gentlypush it anticlockwise until it drops into the slot.

(14) Here the housing and thespring are seen in the correct restposition prior to sewing.

(15)Deflect the spring and checkthat it returns to the correctposition.

When the machine is being usedthe spring will be deflected toabout 9 oclock.

When you come to reassembly,remember to locate the pininside the stud.

Next refit the two discs facingeach other thus: )( , the domedpressure plate dome towards you- and lastly the conical spring andthumbnut.

Screw in the thumbnut for a fewturns and leave further adjust-ment until test time.

(16) The 66/99 tension pins havenothing to hold them in placeand often get lost. A suitablereplacement can be cut from along panel pin, or the tail of a poprivet. It should be exactly 1 long.

(17)When the reassembly iscomplete check that when youlift the presser foot release armthe tension is released allowingthe thread to pull through easilybetween the dished plates.

(18) If the tension does notrelease, remove the faceplate and check inside.

(19) Make sure that when thepresser foot lever is raised, thetension release lever at the backof the face cavity moves across topush the tension release pin.Picture (18) shows the early typeof release lever mechanismwhich is partly obscured by thepresser bar and the needle bar.

(20) In these early models, therelease lever fits into a slot in thebottom of the face cavity, held inwith a pin. This slot clogs with oldoil that has drained into it.

(21) The later type of release leveris held in place with a shoulderedscrew - so that the screw can betightened while allowing freemovement to the lever.


[2] F - 3

16

17

15

2.3.2006

End of tensionrelease pin

Returnspring19

22

End of tensionrelease pin18

21

Type A: Early model with pin location

Type B: Later model with shoulderedscrew fixing.

14

20

13

In both cases the lever mustmove freely and easily. If it doesnot, then work through thefollowing sequence:

Remedial Action:Type A

If you are working on an earlymodel and the tension releaselever is stiff or unmoveable,squirt in some penetrating oil,leave and try again later .

If still in trouble, you might like tonote it for Netley Marsh to dealwith. The lever can be removedbut it is difficult for the followingreasons:

The pin is difficult to remove.

You will probably have toremove the presser bar andneedle bar to clean out the slot.

Then you will need to re-adjustthe needle bar height.

Remedial Action:Type B

On the later model, if the leverdoesn't move freely and easily,make sure the shoulder part ofthe screw is sitting correctly inthe recessed rim of the hole inthe lever.

Remedial Action:Both types

If the lever moves freely and easilywith a screwdriver, but does notmove the pin, check the following:

The screw fastening thepresser foot release lever is tight.

For Type B, the shoulderedpivotal screw holding thetension release lever is tight.

The tension release levermoves when pushed with ascrewdriver.

If the lever is moving OK, but it isnot contacting the pin:

Check that the barrel holdingthe tension assembly is fittingcorrectly in the machine.

(22) The grub screw should locatein the circular groove in thebarrel. The end of the barrelprotrudes about 3/32" or 2.5 mmfrom the side of the machine.

If this is OK, it is probable thatthe release lever has becomebent.

(23) Carefully bend the lever a little so that it can makecontact with the pin at thepoint indicated.

This is relatively easy with type(B) as it has a horizontal barwhich makes contact with thepin, and the lever can beunscrewed and wriggled out ofthe machine for attention.

With type (A) check that the levercontacts squarely with the pin. Itmay be that bending it slightlyaway from you or towards youwill do the trick.

(24) A simple adjustment toolcan be made to tackle this task insitu by cutting a 3/32nd of aninch wide slot, 1/8th of an inchdeep in a piece of 5/16th steelrod.

If this is not an option for you,then it means clearing thepresser bar and needle bar out ofthe way to remove the lever - orleaving it for Netley to correct.

If it the tension lever needs to bebent towards or away from thepin, do not be tempted to use ascrewdriver pressing against theneedle bar for leverage.

In all cases you must make surethat when the presser bar lifter isdown, the tension release leverdoes not continue to press on thepin, as this will stop tension.


[2] F - 4

2.3.2006

2 2

22

Grubscrewlocates in groove

This muchprotudes fromthe side of themachine

24

Type A

23

Type B

The tension stud and spring arechanged from the early type.

(1) The end of the take up springfits into the splines on thetension stud. The stud is a pushfit into the barrel, held by a screw.

To refurbish the Dial Typetension mechanism work yourway through steps A to D in thefollowing Flow Chart. If youencounter a problem follow therelevant numbered symbol tofind the solution.

(A) Raise the presser foot releaselever and check that the tensionis released.

(B) Check that the take up springis in good condition. Pull itgently forward. The springshould come round to approx-imately 1 0clock. Return it to itsposition.

(C) Because the tension spring isenclosed, the unit can usually becleaned with a soft brush, andpassing a cloth between thetension discs. If very dirty, takeapart as described in [2].

(D) Check that, with the presserfoot lever down, when the thumb-nut is turned the tension can beturned up to 10 and down to 0.

(2) The thumbnut should stopturning at position 0, as shownabove.

Remedial Measures

If you have a problem with thetension releasing make the samechecks as described for thesimple type on pages [2] F - 3 & 4

Disassemble

If you have a problem with thepositioning of the tension spring- or pif the tension mechanism isvery dirty - you will need todisassemble the unit as follows:

(3) Turn the thumbnut anti-clockwise until it stops thenpress in the dial to disengagethe pin in the back of thethumbnut from the dial.

(4)Undo the thumbnut andremove all the components down to the tension discs

(5) Now slide out the take upspring, turn it to 1 oclock,and replace it.

(6)Latch the take up spring at11 oclock again.

(7) Test that there is now someresistance to moving it to 9 oclock.


[2] F - 5

2.3.2006

2 2

1

4

5

6

7

1

2

Dial Type (66 & 99)

The springs internaltail slides over one ofthe splines on the stud

ACheck tension release

BCheck take up spring

CCheck cleanliness

DCheck thumbnut

movement

No problemwork down through

Problemmove on to:

3

1

2

2

3

3

2

If there is a problem, the splineson the tension stud haveprobably come loose from thestud. If this is the case, there is noalternative except to change thetension stud.

Rebuild and Reset

If the spring is okay - or you havehad to disassemble in order toreset the dial - you can begin toreplace the components asfollows:

The presser foot release levershould be down before you startthese rebuilding steps:

(8) The tension stud should bepositioned in the barrel so thatthe slot between the prongs ishorizontal. (This allows the dialsetting to be at the top)

(9) If the stud is not positioned horizontally, undo the retain-ing screw located inside the head.

(10) Replace the thumbnut a few turns; use a screwdriver to reposition the tensionstud and retighten theretaining screw

(11) Slide the take up spring over the tension stud at about 1oclock, latch into the correctposition at 11 oclock - as shown on previous page.

(12) Replace the tension discs with the domed sidestogether )(. Replace the tension release washer, with the flat side towards the machine, and the dial setting mark at the top.

(13) Now fit the tension springand stop washer as shown..

(14) Place the numbered dial onthe stud, with the number 2uppermost.

(15) Push the dial towards themachine to compress thespring. Screw on the thumb-nut and carefully guide thepin on the back of thethumbnut into one of theholes on the dial.

Turn the thumbnut anticlockwise.The dial should stop at 0. If not,turn it back to 2, press the dialagain and screw the thumbnut infurther, guiding the pin in to ahole further round the dial.Repeat until the dial stops on 0.

[2] F - 6

UPPER TENSION MECHANISM - (66 & 99 models)2 22.3.2006

13

8

9

11

12

3

15

14

10

At this point there should just bezero tension on the thread. Adjustthis by pressing in the dial(without turning it) and turn thethumbnut (clockwise to increasethe pressure or anticlockwise todecrease) locating the pin in thehole adjacent to the one it waspreviously in. Repeat this untilyou have it right.

Check that the dial will nowrevolve through a completeclockwise turn, stopping on 9.Turn the dial to 5, ready to testthe stitching later.

Finally, test that the tensionreleases when the presser releaselever is raised. If not, thecorrective procedure is the sameas for the simpler type coveredearlier.

UPPER TENSION MECHANISM - (66 & 99 models)2 22.3.2006

[2] F - 7

(1) The components of the 15Kmodel tension mechanism areassembled partly within theirown housing located on the frontof the face plate.

(2) The sleeve (seen hereremoved from the housing) isadjustable so that the sweep ofthe take up spring can beregulated.

(3) The end of the take-up springfits into a groove on the spline ofthe tension stud.

The locating end of the shaft issmooth and not threaded like the66. It push fits into the hole inthe base of the housing.

(4) The tension release pin isflattened at the end that pressesagainst the pressure release disc.

(5) The remaining componentsare the same as the basic 66/99.

(6) To re-assemble, place the sleeve back in the housing,with the cutout end facingtowards you, and rotated towards the middle of theface plate.

(7) Slide the take up spring over the tension stud, makingsure the tail of the spring islocated in the groove in thestud.

(8) Push the tension stud intothe sleeve making sure it is fullyhome. Turn the stud until thetake up spring is at 5 0clock.

(9) Insert and tighten thelocating screw which holds it inplace.

(10) Push the take up springround anti clockwise until itdrops into the cutout in thesleeve

UPPER TENSION MECHANISM - (15K model)

[2] F - 8

2.3.2006

22

15K

2

3

1

4

6

8

5

7

9

10

(11) Now rotate the sleeve anti clockwise until the take upspring arm is horizontal.Insert and tighten thehousing screw.

(12) re-assemble the other components as coveredearlier in the simple 66/99section.

(13) Make sure, when themechanism is reassembled,the rounded end of thepressure release pin protrudes slightly through the back of the casing.

(14) When the faceplate is re-attached the end of the tensionpin is pushed backwards (by thepressure of the tension spring)into the indent in the presserlever arm.

(15) When the arm is raised thepin is pushed forwards out of theindent and pushes back on thetension release plate whichreleases the pressure between thetwo tension discs.

Remedial Measures

If the tension does not release,check that the face plate is fittingclose up to the face, with nodebris inside it and that it hasbeen fastened securely.

If the release lever wobbles about- read on...

(16) Undo the grub screw holdingthe securing pin in place andmake sure the presser releaselever is held firmly in place.

(17) Using a punch, gently tap theend of the release pin untilthe lever is held firmly. If tootight, tap the other end ofthe pin. Finally retightenthe grub screw.

[2] F - 9

UPPER TENSION MECHANISM - (15K model)2.3.2006

2 2

11

12

16

17

14

15

1

2

13

(1) The parts shown abovecomprise yet another variationon the dial-up tension mecha-nism which was introduced withthe early 201s.

The tension spring is enclosed ina housing, so that as thethumbnut is tightened, the twohalves of the housing telescope.

This allows for a simple bar andscale measure of the tensionapplied to be incorporated -which can be seen in the picture.

(1) Clean the unit with a soft brush and between thetension discs with a cloth.

(2) Check the take up spring is in good condition andsprings back to its position when deflected.

(3) If the spring needs more - or less - tension, undo thefastening screw inside the head and turn the tension stud with a screwdriver.

(4) If the spring needs changingor the unit is very dirty, undothe tension stud fasteningscrew, remove the unit andtake it apart.

(5) To re-assemble this type ofearly version first place therear tension housing (E)face down on the bench,with the locating arm in theair.

UPPER TENSION MECHANISM - (201)

[2] F - 10

2.3..2006

22

201 (early version)

A Tension pin with flat endB Tension studC Take up spring 201 type

D Tension washersE Positioning plate joined to

rear tension housingF Tension release washer

G Tension springH Front tension spring housingI Thumbnut

1

2 4

35

This is actually two parts, the reartension housing and the posi-tioning plate.

(6) Put the tension release washer (F) into the rear tension housing, domedside down.

(7) Now place the two tensionwashers (D) on top and slidethe end of the tensionrelease spring between theparts of the rear tension housing in the area of thearrow in picture (6).

(8) Holding the tension release pin in the tension stud with a small screwdriver, place thetension stud into theassembly.

You may need to rotate it to passthe tension release washer butthe worst is over.

(9) Pick the unit up holding it by the tension housing. Reverseit while you add the tension spring and the front tension housing

(10) Tilt this so you can get the tension marker bar into the slot in the rear tension housing. Screw on the thumbnut and the unit is complete.

(11) Insert the unit into themachine arm, locating theguide tail in the small holeabove the housing recess.

(12) Make sure the take upspring is within the cutout and check that it springsback to this position whendeflected.

(13) If it needs more - or less -tension, turn the tensionstud with a screwdriver, thentighten the holding screw inside the face.

[2] F - 11

UPPER TENSION MECHANISM - (201)2.3..2006

2 2

10

8

6

9

12

13

11

7

(1) If the unit looks in goodcondition, clean the componentswith a soft brush to remove fluffand surface dirt. Then, with thetension released, clean betweenthe tension disks with a softcloth.

Check that the take up spring isin good condition. The spring ona type 201 differs from all theother machines because it pulls inthe opposite direction.

With tension off, lift the springoff its rest. It should slip roundanticlockwise to roughly 6oclock. If not the mechanismwill have to be disassembled.

(2) To disassemble, turn the thumb nut anti-clockwise until the numeral 0 on the numbered dial stops opposite the centre lines between plus and minus.

Next, press in the dial todisengage the pin in the back thethumb nut from the dial.

(3) Now remove the thumb nut and dial, stop washer,tension spring and indicator disc.

(4) It is not necessary to removethe stud from the machine arm(as seen here) to disassemble thethread tension - but it does helpto show it for the purpose ofillustration.

However, check that the stud isset with the slot horizontal sothat the pointer for the stitchsetting can be at the top of themachine.

You can see that the 201 has twodifferentiating features comparedwith the other models:

A: The addition of a thread guardplate with a tail at the top whichlocates into a hole in the machinearm.

B: The opposing end of the springhas a circular loop which hooksover the front end of the stud.

In order to have the necessarypretension, the take up springhas to be guided on to the studwith its loop in a vertical position .

To start reassembly, first makesure the tension release pin is inplace in the stud.

(5) Place the two tension plateswith their flat thread-bearing sides together thenpass the circular loop of thespring under the threadguard with the coils of thespring above.

(6) Guide the tension discassembly on to the stud sothat the extension of thethread guard enters thehole in the machine arm.

(7) Replace the indicator withthe large open side facingthe end of the stud so thatthe plus and minus markswill be at the top (with theminus sign at the left).


[2] F - 12

2.3..2006

22

201 Modern Types

6

7

5

Tensionplates

Springtail

Circularloop

Threadguard tail

1

2

3

4

A B

(8) Insert the remaining parts.

Hold the parts thus assembledagainst the shoulder of the studthen inset the tension spring inthe indicator with the first (half)coil of the spring straddling thelower half of the stud.

Then guide the stop washer on tothe stud so that the little hookedbeak is at the top.

(9) If the spring and stop washerare in the correct position, thelittle hook will clear the first(half) coil of the tension spring.

(10) If you look inside thenumbered indicator dialyou will see a small ridgedirectly below numeral 0.

This ridge is for the stop washerhook to engage against whichprevents the whole mechanismfrom coming unscrewed whenthe thumb nut is undone to itsfull extent.

(11) Next place the numbered dial on the stud so that numeral 2 is opposite the stop washer hook.

(12) Now push the dial tocompress the spring so thatthe thumb nut can beturned on to the stud.

Carefully guide the pin on thethumb nut into one of the holesof the numbered dial.

Turn the thumbnut anticlockwise.The dial should stop at 0. If not,turn it back to 2, press the dialagain and screw the thumbnut infurther, guiding the pin in to ahole further round the dial.Repeat until the dial stops on 0.

At this point there should just bezero tension on the thread. Adjustthis by pressing in the dial(without turning it) and turn thethumbnut clockwise (to increasethe pressure and anticlockwise todecreas it) locating the pin in the

hole adjacent to the one it waspreviously in. Repeat this untilyou have it right.

Check that the dial turns togetherwith the thumb nut through acomplete revolution clockwisestopping on 9, providing a fullrange of tensions from light toheavy. Then turn the dial back to5, ready to test the stitching later.

Finally, test that the tensionreleases when the presser releaselever is raised. If not, thecorrective procedure is the sameas for the simpler type coveredearlier.

The take up spring should beresting horizontally, to fine tuneit an adjustment plate is providedwhich regulates the distance theend of the spring travels as itmakes its arc.

(13) Loosen adjustment screwand reposition the take-upspring adjustment plate ifrequired to raise or lowerthe projection arm onwhich the spring rests.


[2] F - 13

2.3..2006

2 2

10

13

Spring restprojectionarm

Adjustment screw

8

9

11

12

2f refurbishing - upper tension mechanism 2

Documents