Backlash Enabled, XYZ Odd Movement

[gbonks]

I have found that when backlash is enabled an odd motor movement on all axis occurs when changing direction.
When you change direction the motors start, then hesitate, then start. They do this sluggishly, then they start to run normal.
When backlash is disabled the motors change direction normal and the problem goes away. It sounds like the same problem
Calum was having in his posted Topic (Unexpected XY Movement). He posted this last year. I don't know if this was ever solved.

Any Idea what the problem might be and how to fix it.

Thanks!

Gary

[DaveCVI]

Hi,
Backlash is handled entirely inside mach (and/or in the motion device plug-in) and MSM has nothing to do with that feature.
Given this, there is nothing MSM can to so effect how mach does backlash compensation.
In general, attempting to correct backlash in software almost always ends up being unsatisfactory. The only good solution I know for backlash is to fix the mechanics of the machine so they the backlash does not exist.
Dave

[gbonks]

Dave!

Thanks for your quick response. You are absolutely correct about getting backlash out of the machine mechanics first. With the present
ball nuts and screws I have now my backlash on all axis is .0025. I don't think I will get any better than this with the present ones I have now.
I had been running a licensed version of Mach3 and MSM for 4 years now and have not had any problem like this with the backlash enabled.
When I recently installed new versions of Mach3 and MSM, this problem showed up with the backlash enabled. Now that I know that backlash is
handled by Mach3 I will try looking on their forums.

Thanks again for your help!

Gary

[DaveCVI]

what version of mach were using before and what is the mach version you recently installed?
Also consider the motion device....
If it is a parallel port then the low level details of step generation are in the mach PP driver.
If it is an external motion device, then a change to the motion device plug-in could be the source of the change in behavior also.
Dave

[gbonks]

Dave!

I am running Version R3.043.066 of Mach3 and the latest version of MSM. After you informed me that backlash was handled by Mach3 I started
to remember that I did have this same problem when I installed Mach3 4 years ago. I just couldn't remember what I did to correct it. Recently
my hard drive crashed and I hadn't saved any settings, Motor tuning, inputs and outputs etc. so I had to start all over from scratch. So after you
informed me it was handled by Mach3, I went to their forum. The Mach3 Moderator in February of this year posted a topic on backlash setting.
I discovered that the Shuttle Wheel Accel setting was set at 0.25. That was to long of a time. After following their recommendations on how to set the
timing, my problem was solved.

Both the Mach3 and MSM are incredible programs and I was really upset when that hard drive crashed.

Thanks for you assistance!

Gary