"old coot" needs help with motor tuning settings........I think.

Picked up a 3020T from inlaws using mach 3. Everything seems to be working fine except z axis movement. Using calibration on axis movement and dial indicator it is usually within .001-.002 on .100" movements. However, when running a program the initial movement in z axis will pause most of the time while the DRO continues to move throwing off my zero setting in the axis. Initial movement towards part in z usually crashes unless caught. Axis hesitates only in positive movement usually about .200" below top home. I've tried screwing around with the motor tuning in this axis (the only axis causing problems) and when manually raising, it will ocassionally go all the way up without hesitation. After it does this 2 or 3 times and I think its straightened out, I'll try to run a program and it usually shows up on the first positioning z move. Do you guys feel like I'm coping with a motor tuning issue or is there a setting I'm overlooking? I really appreciate any attempts at helping, and I'm wishing I had taken up a less mentally demanding hobby at age 70. Thanks.

I sounds like the Z axis stepper is stalling or missing steps, have you checked to see if the axis is binding.

Misalignment or dirt may be the culprit.

Jeff...

Thanks Jeff. Yes I have checked and everything seems to be working freely. Nothing loose on the ball screw, no couplings broken or loose.

Quote:

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Originally Posted by jalessi

I sounds like the Z axis stepper is stalling or missing steps, have you checked to see if the axis is binding.

Misalignment or dirt may be the culprit.

Jeff...

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I will re-check alighnment and for any dirt that may be present again. On some programs, if I watch for the hesitation on the initial z move and it doesn't get out of sinc with the DRO, the thing runs real well, but there have been instances when I questioned my touchoff on the part. Cuts seem to try and go a little deeper than in the program seems like.

I have seen inexpensive spindle motors like the one equipped on the 3020 with bearings that don't control axial movement.

Does the spindle shaft shift up and down when idle?

Jeff...

Quote:

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Originally Posted by jalessi

I have seen inexpensive spindle motors like the one equipped on the 3020 with bearings that don't control axial movement.

Does the spindle shaft shift up and down when idle?

Jeff...

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I've checked for vertical or laterial movement of shaft bearings and there isn't any. I do think I may have found the problem though. I was attempting to run my motor tuning pulse rates (step & dir) set to "1". After changing both of those to "2" and running several calibrations in "settings" it comes withing .001-.002 in 1/2" movements in either direction (+ or -). Guess I'll cross my fingers and try a program or two. Again, I appreciate your help Jeff. You were actually the only one who tried to help this "old coot".

Dick

Change the pulse width to 5. It should be even more stable than at 2, and it won't have any negative effects.

Gerry,

Good call.

If what Gerry suggested helps but does not completely cure the issue try enabling sherline mode.

Jeff...