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how to define tools to cut both directions in z

jimmycornwell

Plastic
Joined
Dec 18, 2011
Location
lake city
i am using a knurling tool on a qt nexus350m. the problem i have is i would like to feed the tool toward the chuck on first pass and reverse direction on second pass so the knurl feeds back over itself. i cant figure out how to define the tool in tool data to allow it to feed z- and z+.. when i try i get a reverse contour alarm. i am new to mazak, this would not be a problem in g-code on my falcon lathe. i would like to write this program in mazatrol instead.
 
i would like to write this program in mazatrol instead.

Use the manual process (MNP) for knurling. This is essentially a manual G-code feature inside the Mazatrol program. I have used it with great success knurling and it only needs 3 lines or so. Define the tool like a regular CNMG turning tool and enter the cutting direction to get chuck to spin the way you want.

Mazatrol does not want to reverse direction in this fashion unless you lie to it and tell the machine you are drilling a hole, but you cannot compensate for taper.
 
could you please send me a sample of the gcode program you use? the part i am knurling is a 2.5"- 11 ga tube with 43" long knurl. the knurls which start at the end of the tube look fine. the problem is the other end of the knurl starts 2 5/8 " from the end and i am having trouble getting them deep enough starting in the middle of the tube.
 
What kind of material are you knurling?
I knurle 4140 and 1018 from time to time and do it in one pass.The knurling tool came with a data sheet to figure feed rate and depth of cut for a given tool.
Can't remember off hand but most of what I have knurled was something like -.014 from major diameter at .007-.010 IPR depending on material.

When I set the tool gemeotry I hand wheel knurling tool down on to OD of part untill both wheels have made good contact then set X at diameter of part.Then I program K tool to rapid to Z- half the knurling tool width past shoulder then X to +.100" of the OD of part then feed down to apporox -.014" under OD diameter I am knurling.Same if knurle has no shoulder to start from.
Then feed to Z- finish length and done with one pass.
Often it takes a couple parts or so to get it right by using X offset to get the correct cut amount for it to work in one pass.
Be aware though,a heavy knurle with one pass will shove a part back in the chuck if it isn't clamped really tight.
 
We use much older machines here but we also definitely don't do a 40 inch knurl in ours, more like 5 inches, I'd imagine you would have to do a test cut and program in some taper for that part. I definitely wouldn't run it over it backwards.

Also like previously stated use the manual program function.
 
Sorry I didn't catch the 43" long part in your post,no matter what that is gonna be a REAL PITA!!
Knurling puts up a LOT of tool force,it's gonna be a real bitch getting it right all the way down.

Would you happen to have a manual machine with a follow rest to do the knurling operation on?
If you could set up the tool so it is just behind the follow rest as it travels it would be cake for someone who runs it.
 
I am using a push type knurling tool. the problem is my material is 11 ga, so I cant clamp with much force in chuck jaws or it eggs the tube. what I finally did was use 2 passes, and set feed override to zero for a few seconds to let the knurls mesh before feeding on 2nd pass
 
I am using a push type knurling tool. the problem is my material is 11 ga, so I cant clamp with much force in chuck jaws or it eggs the tube. what I finally did was use 2 passes, and set feed override to zero for a few seconds to let the knurls mesh before feeding on 2nd pass

Chucking on tube with a hydrualic chuck is a major pain in the dick isn't it.To much pressure and you crush the piece,to little and you lose grip.
What I do in situations like this is make a plug to go into tube on the end I am chucking on to prevent the chuck from crushing the work piece.

Maybe you could do the same?
Make a plug that just slips in so you can crank the chuck presure up.
 
I am using a push type knurling tool. the problem is my material is 11 ga, so I cant clamp with much force in chuck jaws or it eggs the tube. what I finally did was use 2 passes, and set feed override to zero for a few seconds to let the knurls mesh before feeding on 2nd pass

If you do this job often enough consider pie face jaws and a plug. Removes egging, better grip.
 
You can program the pass in 2 moves with a different x value half way down the tube and finish at the starting diameter. If you program the lead in slow you can usually pick up the knurl, keep adjusting the intermediate diameter until the knurl looks uniform.
 








 
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