BACKLASH setting not working

Hi all, we have run into a bit of an issue. As we were trying to set up backlash compensation on our machine, subsequent tests showed that no changes were being made to to rate or lost movement due to backlash. We're running LinuxCNC 2.7.5. We are not running steppers, so the problem can't be the STEPGEN_MAXACCEL setting.

We would be very grateful if anybody could shed any light on this issue. Does anybody know what could be preventing the setting from taking effect? And what can we do to remedy it?

I'm a a little confused. One sentence you are talking about quantities of lost steps, And in the next sentence you say that you are not running steppers?

Could you clarify what hardware you are using?
Are you running servos? Are they position mode servos (step/dir commanded)? Are they closed loop (encoder feedback into Linuxcnc)?

Thank you for clarifying. No, we're not running steppers. What I meant to say was that there was no change in movement lost due to backlash, even after changing the setting in the INI.

Yes, we are running servos. They are closed loop from the servo to it's drive, but it is an open loop from the drive to LinuxCNC. And no, they are not position mode.

I appreciate the quick reply. I've edited the main post to reflect the proper wording of the issue.

How much backlash do you have? Could you upload you ini and hal files so we can have a peek and try to see what's wrong?

We have 3 axes, two of which have about .0015 inches backlash, and the other axis has roughly .009 inches.
The HAL and INI files are attached.

How are you testing the backlash?

My shot in the dark is your servo drives are not tuned well enough to notice a .002" movement...

backlash certainly works - I have just tested it recently.



first ring - backlash enabled - second ring backlash turned off.