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Certification Tutorial

Certification Tutorial 2

CNC

Step Down

Step Over

NC File

Stock

Spoil Board

Feeds

Speeds

RPM

IPM

Profiling

Surfacing

“Computer Numerical Control.” A computer controller reads G-code instructions and drives a tool.

The distance between vertical cutting passes. The default step down dimension should generally be equal to the diameter of the bit being used to cut.

The distance between horizontal cutting passes. This dimension can be smaller to produce smoother results or larger to create more bit based textures. The default step over dimension should generally be half the diameter of the bit being used to cut.

(G code) A file exported from CAM software specifically coded to communicate with the Techno CNC machine.

Material to be milled by the CNC

The MDF board under the piece to be milled. The Spoil Board acts as a buffer between the bit and the table insuring a cut that goes through the material won’t damage the table.

Refers to the rate of cut speeds, measured in inches per minute.

Refers to the rate of spindle rotation, measured in revolutions per minute.

(Revolutions Per Minute) An abbreviation generally used to describe CNC spindle rotation speed in revolutions per minute.

(Inches Per Minute) An abbreviation generally used to describe feed (cut) rates in inches per minute.

Cutting out shapes or pieces to be assembles.

Cutting 3D geometries or textures.

Bit Based Textures

Hybrids

HSS

SC

Carbide Tipped

Flute

Straight

Spiral

Up Cut

Down Cut

Compression

Cutting lines or 3D geometries but using different bits to yield varying and unexpected results.

Combinations of milling techniques and assembly methods to yield new results.

(High Speed Steel) A tool steel that can cut faster than carbon steal. Generally only suitable for foam cuts, generally not used anymore.

(Solid Carbide) A type of wear resistant steal. Quality varies dramatically.

Because carbide is expensive, larger diameter bits are available with chunks of carbide welded to a steel body.

Cutting edges in the body of a tool. More flutes increases the strength of the tool but reduces space for chip flow.

Bits with cutting edges parallel to the body of the bit. Generally the cheapest.

Bits with helix shaped cutting edges that wrap around the body of the bit. Cut smoother and with less vibration that straight bits. Three types: up, down, and compression.

A type of spiral bit with shears from the bottom up that lift material upward, allows for deeper cuts with less stress. Can occasionally lift material off the bed or splinter susceptible materials.

A type of spiral bit designed to cut from the top surface down and tends to pack sawdust from the cut into the groove being cut, leaving a smoother surface. Also helps to keep the material pressed against the bed.

A type of spiral bit with Up Cut edges on the lower half and Down Cut edges on the upper half of the body of the bit. Leaves a smooth cut surface.

Important Terms


Mortise

Standard End

FEM

Ball

V Bits

Form Bits

Plunge

Jog

Mop Set

BBT

Plunge Rate & Angle

3 Axis MillingMilling

2.5 Axis Milling

A special type of Compression Spiral bit characterized by a much shorter Up Cut section, used for shallow but smooth and splinter free grooves.

A bit with a shallow tail style profile at the end of the body. Used for Profile Cutting, leaves swirl marks when Pocket Cutting.

(Flat End Mill) A bit with a flat end profile. Cuts smooth bottom surfaces when Pocketing, but needs to be ramped into the cut or the bit will burn.

A bit with a simple ball shape at its end, used for cutting pockets with a smooth corner or radius.

A bit with a v shaped end, not intended to cut a straight profile. The cut will be affected by the V Bit’s angle and diameter.

Any bit with a particularly defined form at its tip, capable of plunging.

Movement along a vertical axis.

Movement along a horizontal axis.

A term from RhinoCAM that is created in Rhino. It is a set of instructions for describing geometry, cut patterns, dimensions, bits, profiles, speeds, etc. These instructions are exported as an NC file for shop monitors to process.

(Bit Based Textures) An abbreviation for cut patterns that rely on bit depth and step over to create surface character.

The speed and angle of the entry and exit cuts.

Milling operations that engage the X, Y, and Z axes simultaneously (often used to create relief or textured surfaces).Milling operations that engage the X and Y axes simultaneously, and the Z axis independently (often used to create profiled or cut pieces).

Collet

Collet Nut

Arbor

Spindle

The part of the CNC machine that holds the bit. It is a sleeve that attaches to the spindles with a Collet Nut.

The nut that is affixed to the Spindle and holds the Collet.

The part of the CNC machine that allows the spindle to move in the X, Y, and Z axes. The arbor is the framework above the table that holds the Spindle.

The part of the CNC machine attached to the arbor that spins. This is the piece to which you attach the bits with the Collet and Collet Nut.

Naming FilesPlease name your files accordingly:

1 2 3 4 5 6

1_.5Ball_HRough_MDF_Johnson_YYMMDD

1. cut number 4. material2. bit to be used 5. last name3. milling operation 6. date

Files that are not named correctly will not be milled.

Using the ShopTo use the CNC Shop you must bring:

NC file + Rhino file (on flash drive)Printed Shop Documentation fileCutting ChecklistStudent ID

The CNC Shop does not supply:spoil boardsmilling bitsmaterial


Modeling GeometryFirst, let’s make something to cut. In Rhino, set Units to Inches.

For this tutorial we will be working with an 8” x 8” block of 3/4” MDF. Create any continuous 6”x6” surface in the middle of that 8” x 8” cutting area. Make sure that 6”x6” surface is located at (1,1), leaving 1” boarder around the material. It should not rise above 3/4” or fall below 1/8” on the Z axis.

To create a simple surface, draw 4 curved or angled polylines around the 6” x 6” boundary. Select the curves and use the command Sweep2. There are many other methods for producing surfaces

Create a flat polyline as a boundary. This will be the shape of the profiling operation. Create another flat polyline inside the boundary. This is will be the shape of the pocketing operation. Create 5 points that will be drill holes. Those polylines and points should all be at the same height as your material (0.75”).

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B.

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1.

SurfaceProfiling PolylinePocketing PolylineDrilling Holes

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ii. iii.

iv.

i.ii.iii.iv.


RhinoCAMInterfaceRhinoCAM is the interface we use to create everything needed for a CNC cut file. Type the command RhinoCAM2017 to open the interface. Ensure the RhinoCAM drop down menu is set to Mill. Both the Machining Browser and Machining Objects windows should appear. Note that all numbers will be in inches.

Note: Licensed copies of RhinoCAM are only available in the Higgins Hall Computer lab. The demo version is available for download but does not let you post (export) cut files.

A.

2.

AxesIn the Machining Browser window, make sure Machine says 3 Axis. If it doesn’t, double click it to bring up its options menu and change Number of Axes.

PostMake sure Post says Technolsel. If it doesn’t, double click it to bring up its options menu and change Current Post Processor.

StockDouble click on Stock to set a simulation of your material. Make sure the Corner Coordinates are all 0”. Set the Dimensions to L=8”, W=8”, H=0.75”.

Stock geometry, cut paths, cut depths and points should NEVER below 0” on the Z axis. Cutting below 0” can risk milling through the spoilboard and damaging the CNC machine.

B.

C.

D.

B. C. D.


ToolsBefore we can setup a cut we need to setup a simulation of our milling bits so RhinoCAM can accurately create the tool path. Double click on Tools to bring up the Cutting Tools window.

First, let’s create a 1/2” Ball Mill tool. At the top left corner of the window, select the Ball Mill. Set Diameter to 0.5”. Note that the Tool Holder will always be 1.75”, while the other dimensions will be specific to the bit you are using. Having these dimensions accurate will keep cuts smooth and tools from breaking.

Finally, in the name box type 0.5” Ball and click Save as New Tool.

A.

B.

3.

Next, let’s create a 1/4” Flat Mill tool using the same steps. This time, select the Flat Mill, set the Diameter to 0.25 and save it as 0.25 Flat.

C.

A.

C.


Control GeometryFirst we need to set the cut boundary. In the Control Geometry tab, click the Select Curve/Edge Regions button. The window will minimize and allowing you to select the 6” x 6” polyline surrounding your geometry Hit enter after selecting and your cut boundary will be set. The polyline will turn orange and Drive Region 1 should be added to the your Machining Regions.

ToolNext let’s set the tool. Click on the Tool tab and select the 0.5” Ball tool we just created.

Feeds & SpeedsMost importantly, we need to set the Feed Rates and Speeds. Speeds and Feeds will change depending on the material being cut, the bit being used and the desired smoothness of the cut. For this tutorial set Spindle Speed to 14,000 RPM in a Clockwise Direction. Set Punge to 60, Approach to 70, Engage to 80, Cut to 100, Retract to 80 and Departure to 70. Set Cutting Speed to 100 IPM. Set Transfer Rate to Use Rapid. The two Feed Rate Reduction Factors should always be set to 100%.

For future cuts contact your instructor or a CNC shop monitor.

Clearance PlaneNext is the Clearance Plane, the distance at which the machine jogs above the material. Set the Clearance Plane Definition to Stock Max Z + Dist and enter 0.25”.

A.

B.

C.

D.

Horizontal Roughing4.The first milling operation will be a Horizontal Roughing pass which takes large areas of material off before a finishing pass can smooth it out. In the Machining Browser window click on 3 Axis and select Horizontal Roughing. A window will pop up with several tabs that control the parameters of the cut.

A. B.

C. D.


Cut ParametersNow move to the Cut Parameters tab, set the Cut Pattern to Linear. Set the Cut Direction to Mixed. The Stepover Control should always be set to a distance that is 50% the diameter of the tool being used (0.25” here).

Cut LevelsNext is the Cut Levels tab. Set the Stepdown Control to a distance that is 50% the diameter of the tool being used (0.25”) (Note that this dimension is usually equal to the tool diameter (0.5”) but this cut has shallow geometry and is an exception). Set the Cut Levels Ordering to Depth First.

E.

F.

Engage & RetractFinally, select the Engage/Retract tab. Make sure the Always engage in previously cut area if possible box is checked. Make sure the Engage/Retract in Air option is set to Linear Extension with a value of 0.

GenerateNow that all parameters have been set, click the Generate button in the bottom right corner of the window. This will calculate tool paths based on your inputs and create a new Horizontal Roughing machining operation in the Setup 1 folder. If you need to make changes to the tool path you created, simply double click on the folder in the Machining Browser.

SimulateYou should now see an overlay of tool paths over your geometry in Rhino. Blue lines indicate tool travel paths through the material. Red lines indicate tool travel paths above the material. Yellow lines indicate movement in the Z axis. In the Simulate tab of the Machining Browser, highlight the Horizontal Roughing folder and click play to show a preview of the Horizontal Roughing

G.

H.

I.

E. F.

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Control GeometryIn the Control Geometry tab, make sure you select the same 6”x6” polyline as the Horizonatl Roughing pass to keep the cut boundary the same for both paths.

ToolIn the Tool tab, select the 0.25” Flat mill to use this time. Generally the finishing path should use a mill that is 50% the diameter of the roughing path in order to produce a finer resolution.

Feeds & Speeds + Clearance PlaneDouble check that the Feed Rates, Speeds and Clearance Plane are all set the same as the previous operation. If they are not, correct them.

For future cuts contact your instructor or a CNC shop monitor.

A.

B.

C.

Parallel Finishing5.To make our geometry smoother we need to create a Parallel Finishing path. These procedures will seem familiar because they are similar to those used to create the Horizontal Roughing path. In the Machining Browser window click on 3 Axis and select Parallel Finishing. A similar window will pop up with several tabs that control the parameters of the cut.

A. B.

C. C.


Cut ParametersNow move to the Cut Parameters tab and set Cut Pattern to Linear. Set Cut Direction to Mixed. Set the Angle of Cuts to a degree value between 0-90 (this will run the finishing tool path at a chosen degree angle from the roughing path, giving a smoother finish). Under Stepover Control set the Distance to no less than 25% and no more than 50% the diameter of the bit being used. The smaller this dimension, the finer the finish. Since we’re using the 1/4 mill, lets set this to 0.0625”. Note that in a finishing path, you set the stepover distance but not the stepdown distance because the tool path goes right down to the surface of your geometry.

Entry & Exit Finally, in the Entry/Exit tab set Engage Motion to Linear with a length of 0.05” and an angle of 10°. Set Cut Connections to Straight.

Generate + SimulateNow that all parameters have been set, click the Generate button in the bottom right corner of the window. A Parallel Finishing operation will be placed in the Setup 1 folder and an overlay of tool paths will appear. Again, you can make changes to the operation and run the simulation the same way as the previous procedure.

D.

E.

F.

D.

E.


Now that we have the surface smoothed out, let’s drill some holes. In the Machining Browser click on Holes and select Drills. A similar window will pop up with several tabs with parameters that control drilling operations.

Hole FeaturesUnder the Hole Features tab, click on Select Drill Points/Circles to set the holes to drill. The window will minimize allowing you to select the 5 points you created. Hit enter after selecting.

ToolNext, in the Tool tab, select the 0.25” Flat mill.

A.

B.

C.

D.

E.

Drilling6.


Cut ParametersFinally, let’s go to the Cut Parameters tab. Under Depth Control set Drill Depth to 0.76” (because the tutorial material is 3/4” thick, this ensures a clean drill. Do not cut too deep and never cut through the spoil board).

Generate + SimulateNow that all parameters have been set, click the Generate button in the bottom right corner of the window. A Standard Drill operation will be placed in the Setup 1 folder and an overlay of tool paths will appear. In this case red lines are jogs, blue lines are drilling operations. Again, you can make changes to the operation and run the simulation the same way as the previous procedure.

A. B.

D.


Now we’ll cut a chunk out of the material. In the Machining Browser click on 2 Axis and select Pocketing. A window will pop up with several tabs with parameters that control pocketing operations. Again, these options look familiar.

Control GeometryUnder Control Geometry, click the Select Curve/Edge Region button. The window will minimize allowing you to select the smaller, interior, polyline that you want to use for the pocketing procedure. This polyline should be located at the top surface of your stock (Z = 0.75”).

ToolClick on the Tool tab and select the 0.25” Flat Mill that was created earlier.


Cut ParametersNow let’s move to the Cut Parameters tab. Set Cut Pattern to Offset. Set the Cut Direction to Conventional (Up Cut). Set the Start Point to Inside. The Stepover Distance should always be a value 50% the diameter of the bit you are using (0.125” here).

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B.

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D.

Pocketing7.A.

B.

D.


Cut LevelsNow move to the Cut Levels tab and set Location of Cut Geometry to At Top. Under Cut Depth Control set the Total Cut Depth to the depth you want your pocket to be. This tutorial uses 0.7” as an example.” Set Rough Depth equal to the diameter of the end mill (0.25”). Set the Cut Levels Ordering to Level First.

Entry & ExitLast is the Pocketing Entry/Exit Tab. These values should be a default based on the Techno machine but it’s best to check they are correct. Set Engage Motion to Path with an angle of 10° and a height of 0.05”. Set Retract Motion to Linear

Generate + SimulateNow that all parameters have been set, click the Generate button in the bottom right corner of the window. A 21/2 Axis Pocketing operation will be placed in the Setup 1 folder and an overlay of tool paths will appear. Again, you can make changes to the operation and run the simulation the same way as the previous procedure.

E.

F.

G.

E.

F.


Control GeometryUnder Control Geometry, click the Select Curve/Edge Region button. Again, the window will minimize allowing you to select a polyline that you want to use for the profiling procedure. This time use the larger, outer polyline located at the top surface of your stock (Z = 0.75”).

ToolClick on the Tool tab and select the 0.25” Flat Mill that was created earlier.

Cut ParametersNow move to the Cut Parameters tab and set the Cut Direction to Conventional (Up Cut). Set Use Outside/Inside for Closed Curves to Outside.

Cut LevelsNext, click on the Cut Levels tab. Set Location of Cut Geometry to At Top. Set the Total Cut Depth to 0.76” to ensure the material is completely cut out. Set the Rough Depth/Cut equal to the diameter of the end mill (0.25”).


A.

B.

C.

D.

E.

Profiling8.Finally, we can profile the edge of the material. In the Machining Browser click on 2 Axis and select Profiling. Again, a familiar window will pop up with several tabs with parameters that control pocketing operations.

A. B.

C. D.


Entry & ExitNow click on the Entry/Exit tab. Set both Entry Motions and Exit Motions to None.

Generate + SimulateNow that all parameters have been set, click the Generate button in the bottom right corner of the window. A 21/2 Axis Profiling operation will be placed in the Setup 1 folder and an overlay of tool paths will appear. Again, you can make changes to the operation and run the simulation the same way as the previous procedure.

F.

G.

F.


PostingWe’re finally done creating the tool paths. Now we need to export them.

Make sure to double check all of your settings for each operation, especially Feed Rates, Spindle Speeds, Cut Depths and Step Overs. These settings are critically important in keeping cuts high resolution and keeping mills from breaking. Nothing in your Rhino file should fall below 0 on the Z axis and you should never drill through the spoil board.

A.

B.

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9.

PostingNext, it is important to post (export) each individual milling operation one by one rather than the whole MOPset. Right click on the first milling operation (Horizontal Roughing) and choose Post. This will convert your operations in RhinoCAM into an NC file with a series of text based instructions for the Techno CNC Machine. A window will pop up. Set File Type to NC. Set Current Post to Technolsel. Save the file according to the CNC Shop file naming convention. Click Post to save and repeat for each milling operation.

Shop DocumentationRight click on the Setup 1 folder and choose Shop Documentation. This creates a description of your milling operations with information on the tools, speeds, cut time, etc. A window will pop up. Set the File Type to .html. Click save. Print this file.

Using the CNC ShopTo use the CNC Shop you must bring:

1. NC file + Rhino file (on flash drive)2. Printed Shop Documentation file3. Cutting Checklist4. Student ID

Please name your files accordingly:

1 2 3 4 5 6

1_.5Ball_HRough_MDF_Johnson_YYMMDD

1. cut number 4. material2. bit to be used 5. last name3. milling operation 6. date

A.

B.


ChiploadChipload refers to the size of the chip of material cut by each cutting flute each time it passes through the material. It is based on the number of flutes the tool has, the spindle speed, and the feed rate. Cutting with the appropriate chip load calculation will result in the smoothest possible finish and will prolong tool life.

Note: These chiploads assume the cut depth is 1 x the diameter of the tool. Deaper cuts require shop staff approval and should follow these guidelines:2 x D = .75 x chipload3 x D = .5 x chipload

.006 - .008 .003 - .005 .005 - .007 .003 - .005 100ipm / 18k

.006 - .008 .003 - .005 .005 - .007 .003 - .005 100ipm / 18k

.006 - .008 .004 - .006 .006 - .008 .004 - .006 100ipm / 18k

100ipm / 18k

.007 - .009 .005 - .007 .006 - .008 .005 - .007

.007 - .009 .005 - .007 .006 - .008 .005 - .007 100ipm / 18k

.008 - .010 .006 - .008 .007 - .009 .006 - .008

.008 - .010 .006 - .008 .007 - .009 .006 - .008 100ipm / 18k

100ipm / 18k

.008 - .010 .007 - .009 .007 - .009 .007 - .009

.008 - .010 .007 - .009 .007 - .009 .007 - .009

.009 - .011 .007 - .009 .008 - .010 .007 - .009 100ipm / 18k

52-244 1/8” flat endmill

52-244B 1/8” ball endmil

52-360B 3/16” ball endmill

52-564 1/4” flat endmill (foam only)

52-285/7 1/4” flat endmill (no foam)


52-330 3/8” flat endmill (no foam)

52-320B 3/8” ball endmill

52-574 3/8” flat endmill (foam only)




Soft Wood Hard Wood MDF Plywood Blue Foam Tool Number

For the AXYZ router in denser materials, start with a feed rate of 200 IPM and adjust up or down so that spindle speed is in the 8,000 - 16,000 RPM range. Appropriate feed rates and spindle speeds vary by machine.

For blue foam, use 500 IPM as the feed rate for roughing passes, and 200 IPM or lower for finishing passes, with a spindle speed a spindle speed of 18,000 RPM.

Do not use this combination56-200 series tool recommended

Glues to use:

WoodsWood GlueGorilla Glue

FoamsGlidden GripperGorilla Glue3M Spray AdhesiveWood Glue (only for high density foam)

PlasticsGorilla GlueLiquid Nails

LaminatingLamination Techniques

Apply glue evenly across the entire surface of both materials being laminated.

Allow 2 - 24 hours to cure based on instructions.

Most glues expand as they cure — be sure to sufficiently clamp your material.

Consider laminating a single layer of foam to a more rigid material, like wood, to prevent warping during the milling process.

To evenly distribute pressure, place long pieces of wood across the face of your material and clamp at both ends.


Purchasing Bits

Third Avenue Grinding Shop Inc4116 3rd Ave (Unit 1)Brooklyn, NY 11232(718) 768-5546M-F 9-5

Lafayette Grinding LLC115 Banker StreetBrooklyn, NY 11222(718) 388 5973M-F 9-5

onsrud.comrazorsharpgrinding.combamcarbide.com

Purchasing Materials

Precision BoardS&F Supply Store Brooklyn110 Emerson PlaceBrooklyn, NY 11205(718) 399-3333M-Th 8-4:30, F 8-1sfsupplies.com

CorafoamPioneer Supplies1150 Taylors Lane (Unit 4)Cinnaminson, NJ 08077(888) 494-9522

CNC Resources

talkshopbot.com/forumcnczone.commachinetoolhelp.compracticalmachinist.comcocci.comtechedcnc.comsupport.technocnc.com

RhinoCAM Resources

mecsoft.com

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Soft WoodPineSoft MapleFirSpruceHemlockCedarRedwood

Composite WoodOSBMDFLDFMelamineParticle BoardPlywoodMasonite

Possible MaterialsPlasticABSPolycarbonatePolyethylenePVCPolypropylenePolystyreneCast & Extruded AcrylicHDPEUHMWMarine PVCLexanPhenolicSintraNylonLuciteSolid Surface MaterialsLuanPETAcetateVHMWMica

FoamEVAPrecision BoardSign FoamPolystyrenePolyethyleneStyrofoamPolyurethaneFoam RubberSilicone RubberUrethane

OtherRen BoardVinyl Coated PanelsButter BoardMagnetic Rubber MatsCompositesLeatherMother-of-PearlWood VeneersG10DelrinMat BoardRubber

ApplicationsFurnitureProsthetic ManufacturingPrototypingAerospaceMannequin ProductionMusical Instrument ManufacturingBoat BuildingWoodworkingCustom MillworkCabinetryFixturesChannel LettersJoinerySign MakingJewelry ManufacturingCAD/CAM InstructionalModel MakingCountertop ProductionSolid Surface ProductionRadius MoldingsFoam PackagingExtrusions Cutting BoardsFabricatorsSafety EnclosuresEngravingsConveyor ManufacturingPool CuesKnife Template ManufacturingFan Blade ManufacturingGun Stock ManufacturingArtistic CarvingsPuzzlesDoors

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