This week, the author was able to complete a part on the Tormach CNC mill by cutting it with a program they created. Some issues were encountered including breaking drill bits which required adjusting speeds and feeds. Not all tasks like using a reamer were completed due to a hole issue. Lessons were learned about using simple Gcode commands. Several problems came up during the program run like breaking tools which required stopping and making adjustments to complete the job. Some dimensions of the finished part were out of tolerance. Plans for next week include continuing to improve the process and make another part.

1. MillingDisconTormach CNC Mill - Weekending2/15/15:
Pat Graebing
Summary: This week Iwasable to complete apart on the Tormach CNCMill by cuttingit withmyprogram. Initially,Ibroke 2drill bitsbut
adjustmentswere made tothe drill feedsandspeeds ANDtoDeepdrillingwhichrequiresfull retract. Iaddedthe smallerdiameterdrill(metric
6mm size isveryclose to ¼” size thatI wanted) tothe CAMfile togive holesclosertothe drawingrequirement. Use of the reamerwas not
completeddue toissueswithone of the holes.
Preliminary:
Preliminaryfinishingof the topand bottomsurfacesof the piece were done withaflycutter.
Lessonlearned: SimpleGcode commandscan be usedtomove the cutter across the part. Example:
M3 S1000 – rotatesthe spindle clockfloodwiseat1000 rpm.
M8 - floodcoolanton.
G1 X-5 F4 – cuts a pass across the part at the current Z an Y positionbuttravelsatfeedrate = 4 (slow) fromthe currentlocationtoX -5. This way
youcan cut back and forthacross the part at a regulatedspeedandfeed.
NOTE: The smallerfly cutterdidnotgive assmootha finishaswas seenonthe manual mill usingthe longerflycutter.
Afterfinishingthe top,the partwas flippedovertoevenoutthe otherside. Nowthe part shouldbe sittingsquare tothe vise holderandready
for the program to run. Use of simple Gcode linesisgoodforfindingthe part“0” withedge-findertool.

2. TEST AirPASS:
Since thisprogramwas modeledbyme,Iwantedtoperforman “air pass”before millinganymetal. Youneedtofindthe “0” pointforall the
axes. For “air pass” I addedabout5 inchestomove the Z axiszeropointup above the part.
Problem1: The cuttingheadplungesdowntomy part on the firstair pass.
Solution: Tool numbersinthe programneedtomatch the tool numbersinthe tool table for the Tormach. The tool was plungingbecause there
was noheightenteredforthe firsttool inthe program. I re-enteredthe tool table tomatchmy program. Toolsin the librarysometimeshave a
tool numberthat comesoverwiththemtothe CAMfiles. Thiscanbe changedas you make the program.
Final Tool table:
Tool # Description Diameter, inches Height, inches
5 Drill , 6mm,2 flutes 0.236” 4.365”
3 3/8 endmill;2 flutes 0.375” 3.464”
2 6 flute reamer,.251 0.251” 6.182”
Afterthis,nofurtherproblemswere seenonthe airpass.
Program Run:
Problem2: I broke the LetterB drill bitonthe firststepandfirsthole of my part.
Discussion:Ihadtrouble gettingthe coolanttoflow. The mill wasrunningveryfastand broke off the tool.
Solution: Ichangedto a LetterC drill thatI had in reserve andmade sure the coolantwasflowingbefore the start –use manual.
Problem3: Nextrunwiththe C drill andit breakstoo! Itis not justcoolant. (1) I see that the drill doesnotretract afterthe firsthole. (2) I also
see that the drill seemstobe stickingoutof the tool holder. Comparisontoanotherdrill inacolletchucktool holder,itseemstohave less
lengthexposed. The DCconfirmsthatthe collettool holderwill give bettercontrol of the bitthanthe 3-pointtool holderthatI wasusing. (3)
The DC indicatesthatmaybe 40 in/ministoofast forthe feedrate.

3. Solution: Igo back to the program andfindthat I can retract the drill higherwith “Deepdrilling”selectedthatforcesthe drill tofullyretract. I
add the 6 mm metricdrill (0.236”) tothe programsince thisis close tothe size that I expectedforthe letterBandC drills. Ireducedthe plunge
feedrate to 12in/min. Re-save the programandpost the code.
Problem4: Since I hadbrokenall of the drill bitsof the size that I needed, Imovedmypartout of the holder. The DCsuggestedthatI coulduse
a metric6 mm drill or6.1 mm or evena 15/64 drill. I foundtheydidhave a 6 mm drill inthe drillsyoucan borrowat the desk. Due to moving
the part, I wouldnotbe able to line upthe firsthole withsubsequentdrilling.
Solution: Iwantto continue torun the program and findanyotherissueswiththe programrun. I mountthe part onthe vise andre-setall the
“0” pointsforthe axes – X,Y and Z.
The part hasa double hole atthe firsthole of the 6-hole circle.
Drilling6hole circle:

4. Change tool to the End mill tocut the centerholes:
Lots of coolantto keepthe chipsmovingoutof the closedendpocket.
Problem5: Asthe End mill beginstocutthe centerpocketwider,aloadscreechingnoise comesoutof the tool. I hitthe E stopthinking
somethingisverywrong. Hittingthe E stopdisengagesthe motorsandsoyouloose the “0” pointsonthe part. I couldhave hitthe free stop
and had an easierrestart.

5. Part afterEstop:
Solution: The DCsays nothingiswrongwiththe tool and I can continue butinstoppingthe program, (1) I have to re-findall the “0” s foreach
axisand (2) I will have torestart the programat the stepwhere itwas halted.
(1) Change back to edge finderandindicate the edgestofindthe centerpointforXand Y-axis. Re-indicate the topof the partfor Z-axis
“0”.
(2) Change back to the endmill tool. Startthe spindle turningforthe correcttool # and speed. Clearthe stopsandstart the program.
Startingon the line afterwhere youwanttorestart the program worksandthe programstarts up again.

6. Outside Diameter:
The end mill continuesthe programtocut the outerdiameterof the part.

7. CNCProgram Completed:
Cut off finishedpartfromthe blockand face off the roughend.
Problem6: Usedthe chopsaw to cut off the finishedparttotry and save time butthere wasnot enoughsupporttoholdthe part at a right
angle while sawing. The resultwasa crookedpart. Notsufficientstocktolevel off the partheightwithouttakingitbelowsize.

8. Final Dimensions:
Actual Measurement DrawingRequirement
OuterDiam. 2.688” ** 2.688” +0, -.004
thickness 0.886” max.**/0.803” min. 0.875”
ID firstpocket 1.181” 1.313”
FirstpocketDepth 0.403” 0.375” +.002,-.001
ID lowerpocket 0.8815” 0.875” +0, -.004
ID 6 holes 0.248” 0.250”
ID 6 holes 0.247” 0.250”
ID 6 holes 0.250” 0.250”
ID 6 holes X bad hole 0.250”
ID 6 holes 0.248” 0.250”
ID 6 holes 0.250” 0.250”
Centertocenter( diam.Of 6
hole circle
2.0715” 2.063”
X Bad hole 2.063”
Centertocenter( diam.Of 6
hole circle
2.074” 2.063”
See drawingsketchonnextpage.

10. PlansforThis Week:
Reserve more time onthe Tormach.
(1) Continue askingmore experiencedmachinistswhythe firstcenterpocketseemstogotoo deep.
(2) Addball mill toprogram to cut out radiusinfirstcenterpocket.
(3) Try to make anotherpart on the blockremaining. Improve cutoff method.
Currentorderof operationsplanned:
Face off bothendswiththe flycuttertool.
Attach toolstoholdersandmeasure them.
Load the program fromthe desktop. Create the tool table.
Mount the firsttool,edge finder. Findthe 0and setX and Y-axis“0”.
Mount the firstcuttingtool. Set “0” forthe Z-axis.
FollowCNCprogram.
Cut off the part fromthe blockwithenoughstocktofinishtothe thicknessneeded.
Finishthe roughend.