motors or software

[bgnandt]

when I move the table it always comes up 1 turn short. This amounts to
1/8". If I try to move the table 1/8" it will not move at all. If I move the table
a little more than 1/8" the motors will twitch. I have changed computors
and the prolem remains. These motors worked at one time. I switched the
starting accel. and the max accel. while experimenting with the settings.
This means the motors started out faster than the max accel. would allow.
Is it possible I burned something out in the controller? I checked all the
hardware for backlash, and it is o.k.

[ger21]

Set the start very low and lower the acceleration and see if it still does it.

[bgnandt]

I have tried setting the accel. and starting speed (1 i.p.m.) slower. This does help
very minimally. I even tried switching computers and that did not help.

[ger21]

Set the start speed really low, like 10.

[DieGuy]

What contrioller and what motors? How much initial force does it take to get moving?

[rustyolddo]

Ideally look up the specs on your motors, look at the torque curves for the mode you are running, bipolar or unipolar. Find the peak torque and the speed (Hz) where it occurs. For example, my motors reach peak torque at 200Hz. Set your Start speed to that. Set your accel to 10 times that min. and your max to 2.5 times the accel. These are just for starters. It sounds like you are missing steps presuming your backlash compensation isn't the problem. Also, keep in mind as steppers increase in speed, they lose power (torque) This is the reason for going to servo motors.

[Halfnutz]

Ive been using TurboCNC from the beginning of my CNC experience, and Ive grown to really like it, although I am looking forward to migrating into MachII whenever I get around to upgrading my shop computer. For now, at least until today, Turbo's worked fine.

Today I was adjusting my table, just getting it true and flat, its MDF and its prone to sagging. I was adjusting my Z height and running a simple part file over and over when all of a sudden the Z axis locks up going south and burries the tool piece into the table! Ive never seen Turbo do anything that crazy, but I checked out the hardware and everything seems right. After re-zeroing the Z axis I ran the same program a couple more times with no problem. I geusse I'l post at the user site but I saw this post and it seems similar enough I thought I'd throw this in. Has anyone else had Turbo lock up like that? Is it possible that Turbo could be the culprit? Maybe a power glitch or something with my controller (HobbyCNC 3 axis)?