Before I start, I would like to say that I have spent the last week or so reading forum after forum about the various woes associated with backlash compensation. It was only about halfway through my search that I realized the odd relationship between mach 3 builds and the G540 controller... I guess its been cleared up since 09'-10'??
For the last couple of weeks I have been struggling to put the finishing touches on my 'JoesCNC Hybrid" rack and pinion CNC router. The main issue is that when enabled, the backlash compensation causes very rough movement when the compensation is actually utilized. Here is a short video where the machine moves around a 10" x 10" square, ending with a diagonal move to the center:
http://www.youtube.com/watch?v=ClhI3ujGxks&context=C39d6143ADOEgsToPDskJ5XPMdYpc8zU6xOPTZdKYWThus far, I have tried the following:
1.Tore down and rebuilt each of the mechanical components twice in an effort to remove as much mechanical backlash as possible. In general, I am very pleased with the results: backlash of 0.0043" in the y-axis and 0.0070" in the x-axis (zero-backlash nut in the z-axis does a great job).
2. Re-read the mach 3 manual and performed a careful step-by-step re-installation of the software.
3. Verified BIOS settings for the parallel port.
4. Sent my controller back to Gecko to have them take a look at it. They couldn't find anything specifically wrong with the drivers, but they replaced the motherboard as a precaution.
5. Tuned the g540 trim.
6. Changed shuttle accel setting. I read several accounts of people changing this value from 0.005 (my current setting) to 0.05, and 0.5; the vibration that you hear in the video gets worse and worse as I go toward 0.5 setting.
Naturally, I can turn off backlash compensation and everything sounds / moves fine. I wanted to see if anyone else has run into this combination of symptoms before I request phone support, but if it gets to that point, I will post the results. My XML file is attached.
Thanks,
Anthony