[concombrefrais]

I was engraving a part yesterday with a diamond drag tool on my brand new 770. The part had 25000lines of g codes and thousands of z axis move from -0.1 to 0.05. After about 10minutes the engraver was up by more than 0.1in, and cutting air. I checked the tool, made sure it was tight, made sure the part was not moving and tried again. Same result. Tried again after making sure I had CV on (recommended on the tormach manual), had a feedrate of 50ipm on each axis and no feedrate override (also recommended). The head still slowly drift up. Kind of strange since one might think if I am losing steps, it would be when the head is going up and consequently the diamond should go deeper and deeper (worst in many ways).
It does not seem to be an issue on any other axis, or if it is, on a much smaller scale not detectable by looking at the engraving.
Any idea what could be happening here? Anyone had a similar problem?

[Magnum164]

I was engraving a part yesterday with a diamond drag tool on my brand new 770. The part had 25000lines of g codes and thousands of z axis move from -0.1 to 0.05. After about 10minutes the engraver was up by more than 0.1in, and cutting air. I checked the tool, made sure it was tight, made sure the part was not moving and tried again. Same result. Tried again after making sure I had CV on (recommended on the tormach manual), had a feedrate of 50ipm on each axis and no feedrate override (also recommended). The head still slowly drift up. Kind of strange since one might think if I am losing steps, it would be when the head is going up and consequently the diamond should go deeper and deeper (worst in many ways).
It does not seem to be an issue on any other axis, or if it is, on a much smaller scale not detectable by looking at the engraving.
Any idea what could be happening here? Anyone had a similar problem?

Yes. Did you load the recent Tormach patch? What solved my problem was re-installing Mach3 and not applying the patch. So far it has been ok, but I noticed today it was not moving correct, probably only within .0001 of what it should be.

[concombrefrais]

I only installed the version of mach3 which came with the machine. I have not updated anything. You had the same problem? If it is computer related, why only the z-axis?

Yes. Did you load the recent Tormach patch? What solved my problem was re-installing Mach3 and not applying the patch. So far it has been ok, but I noticed today it was not moving correct, probably only within .0001 of what it should be.

[Magnum164]

I only installed the version of mach3 which came with the machine. I have not updated anything. You had the same problem? If it is computer related, why only the z-axis?

Similar, can't say it was the same. I have an older machine than yours probably, could be your software is already the patched version. I never heard back from Tormach as to why when I removed the patched version my started working and I have not loaded it back either. And it happened twice, and both times the system worked fine until I rolled it back to the pre-patch state.

You might want to send Tormach a note, they are very responsive. It's not really computer related, but software. Software does get corrupted sometimes due to crashes or being shutdown while the program is still running. If everything was running fine and now it's bonkers, I always verify software first. It's easier.

[concombrefrais]

I will call them tomorrow. I suspect that the problem was there before but since I never run a program with more than say 50 rapids in z, the drift may have been too small for me to notice. I'll keep everyone posted but meanwhile, feel free to jump in if you have a suggestion. Thank you Magnum.

Similar, can't say it was the same. I have an older machine than yours probably, could be your software is already the patched version. I never heard back from Tormach as to why when I removed the patched version my started working and I have not loaded it back either. And it happened twice, and both times the system worked fine until I rolled it back to the pre-patch state.

You might want to send Tormach a note, they are very responsive. It's not really computer related, but software. Software does get corrupted sometimes due to crashes or being shutdown while the program is still running. If everything was running fine and now it's bonkers, I always verify software first. It's easier.

[bhaas3]

This is my first post on cnczone, I had a similar problem on my 4x8 buildyourcnc.com kit machine. z was drifting up after a 6000 line v carve by more than an inch, and y was also moving in the + direction by over an inch. Check your kernal speed and set it to the lowest setting. (should be 25000). This fixed my problem. Might be something to look into.

[concombrefrais]

Thanks for your suggestion. However, I don't think the mach3 version for the tormach has the option of changing this setting. Please correct me if I am wrong.

This is my first post on cnczone, I had a similar problem on my 4x8 buildyourcnc.com kit machine. z was drifting up after a 6000 line v carve by more than an inch, and y was also moving in the + direction by over an inch. Check your kernal speed and set it to the lowest setting. (should be 25000). This fixed my problem. Might be something to look into.

[Magnum164]

And I need to clarify after readin your post again. Mine did not loose steps in this way, it just never came back to the same setting. If it went to Z2.00 it cam back to Z0 with a tolerance of about .03... But i had been doing manual machining for a while and had not noticed it. But my parts were always a little out of tolerance

[mayhugh1]

Check that the setscrews in the z-axis stepper motor coupler are tight. You can mark the coupler/shaft with a marking pen and see if, over time, the coupler is slipping. - Terry

[racingdave]

Check that the setscrews in the z-axis stepper motor coupler are tight. You can mark the coupler/shaft with a marking pen and see if, over time, the coupler is slipping. - Terry

This is exactly what i did. I ended up buying new bolts for the z-axis coupler and cranking down on them. it fixed my issue.
-dave

[bobeson]

During my first year of owning a new PCNC1100, I found that all three axis couplers needed to be tightened; I would recommend that owners go and perform this step proactively. I've read numerous other stories of people having coupler issues because of loose bolts. In addition, I found that the six bolts holding my spindle cartridge onto the head casting were loose and causing problems. Once I tightened these all up, I haven't had any further problems with them, which leads me to believe that either the factory was not correctly torqueing the fasteners, or the assembly torque specs are too conservative (low) for the application.

While you're tightening up your couplers, it's a good idea to get familiar with your gibs adustments too - optimizing these can make the machine operate much more smoothly if it seems to be getting a little rough. A true optimization is something I don't know how to do properly, but following Tormach's "open-loop" adjustment procedure and iteratively trying a few tweaks here and there has led me to noticably improved performance twice now. I also tweaked the gibs once without any improvement, but that time it turned out that the roughness was caused by my way oil reservoir running empty without my noticing, so the ways had lost their lubricating film for a short while. D'oh! No harm was apparent though, and once I relubed the machine it was all good.

[concombrefrais]

Thank you for the suggestion, I will check all the bolts.

During my first year of owning a new PCNC1100, I found that all three axis couplers needed to be tightened; I would recommend that owners go and perform this step proactively. I've read numerous other stories of people having coupler issues because of loose bolts. In addition, I found that the six bolts holding my spindle cartridge onto the head casting were loose and causing problems. Once I tightened these all up, I haven't had any further problems with them, which leads me to believe that either the factory was not correctly torqueing the fasteners, or the assembly torque specs are too conservative (low) for the application.

While you're tightening up your couplers, it's a good idea to get familiar with your gibs adustments too - optimizing these can make the machine operate much more smoothly if it seems to be getting a little rough. A true optimization is something I don't know how to do properly, but following Tormach's "open-loop" adjustment procedure and iteratively trying a few tweaks here and there has led me to noticably improved performance twice now. I also tweaked the gibs once without any improvement, but that time it turned out that the roughness was caused by my way oil reservoir running empty without my noticing, so the ways had lost their lubricating film for a short while. D'oh! No harm was apparent though, and once I relubed the machine it was all good.

[shred]

Are you 100% sure the tool hasn't moved? I was tearing what little remaining hair I had out one day when my Z depth started going awry. I was sure my Z was wandering so I re checked the gibs, Z-axis, re-marked and redid the bolts, checked for stray ESD, black cats & lightning, etc, etc. The tool felt good and snug, but eventually I re-measured it and sure enough it was very slowly pulling out.

[concombrefrais]

Yes, I am sure it was not the tool. The spindle was off, the only downward pressure involved is to push a light spring down and the tool was tight. The problem must come from somewhere else.

Are you 100% sure the tool hasn't moved? I was tearing what little remaining hair I had out one day when my Z depth started going awry. I was sure my Z was wandering so I re checked the gibs, Z-axis, re-marked and redid the bolts, checked for stray ESD, black cats & lightning, etc, etc. The tool felt good and snug, but eventually I re-measured it and sure enough it was very slowly pulling out.

[Magnum164]

My problem is no where near as pronounced as yours, but I have sent Tormach a note. Resetting back to Z0 come to within .0003 at times (max has been .0015), never back to Z0. that explains why a batch of parts I recently made I had a few parts out of tolerance on thickness. A little frustrating at most. I have tried everything and at the point I believe this is more a software issue, or some setting in M3 that is incorrect.

[Kingjamez]

My problem is no where near as pronounced as yours, but I have sent Tormach a note. Resetting back to Z0 come to within .0003 at times (max has been .0015), never back to Z0. that explains why a batch of parts I recently made I had a few parts out of tolerance on thickness. A little frustrating at most. I have tried everything and at the point I believe this is more a software issue, or some setting in M3 that is incorrect.

I'm not a Tormach user, but getting your Z to repeat to 0.0003 is fantastic. I'd be happy with 0.0015. I find that Mach is not repeatable past about 0.0005" and if I program in (X,Y too) Z0.50 it often will go to Z0.5004 or something like that. My question for you is if your measuring your head, or looking at Mach's readout.

To the OP, you could end all the debate on tool holding by putting a DTI on your head and seeing exactly what is going on on your mill vs. what Mach says is going on. I'd be highly suspect of a software issue. If I were you, I'd lower your Z acceleration along with your max speed by about 1/2 (overkill, but good for a test). Then run your engraving program again and see what happens. A software issue will result in the same problem, and if you are loosing steps, the problem should go away.

-Jim

[Magnum164]

I'm not a Tormach user, but getting your Z to repeat to 0.0003 is fantastic. I'd be happy with 0.0015. I find that Mach is not repeatable past about 0.0005" and if I program in (X,Y too) Z0.50 it often will go to Z0.5004 or something like that. My question for you is if your measuring your head, or looking at Mach's readout.

-Jim

I am more worried about the occasional .015 which is not within specs. As far as measuring the head not sure what you are referring to. I have tried two ways, moving M3 back to Z0 which when measured at the spindle is off, or if I move the machine back to zero my DTI, M3 reading is off. So either way does not matter.

If my machine is resetting in the range of .015 (which is always on the plus side never negative) then if I ran the part as the OP posted I could see my Z creeping further up on each reset.

[Kingjamez]

I am more worried about the occasional .015 which is not within specs. As far as measuring the head not sure what you are referring to. I have tried two ways, moving M3 back to Z0 which when measured at the spindle is off, or if I move the machine back to zero my DTI, M3 reading is off. So either way does not matter.

If my machine is resetting in the range of .015 (which is always on the plus side never negative) then if I ran the part as the OP posted I could see my Z creeping further up on each reset.

There is a pretty large difference between 0.015 and 0.0015. Which is it?
My measuring question was: If you zero a DTI, move the head back and forth. When you command zero, does it go back to zero?

-Jim

[Magnum164]

There is a pretty large difference between 0.015 and 0.0015. Which is it?
My measuring question was: If you zero a DTI, move the head back and forth. When you command zero, does it go back to zero?

-Jim

I don't want to steal the thread from the OP. But would the solution be different if it were .015 or .0015?

And to answer your question. NO. It does not go back to zero.

[concombrefrais]

Absolutely no problem Magnum, I appreciate your input and I am glad if you can find help here for your similar (but most likely different) problem. By the way, thank you again for everyone's suggestion. I will work on fixing the problem next week end and will come back with some update.

I don't want to steal the thread from the OP. But would the solution be different if it were .015 or .0015?

And to answer your question. NO. It does not go back to zero.