I recently converted a BF20, and am still using the stock screws. I measured the backlash in the x and y direction, and entered it in Mach3's backlash compensation screen.
All seems to work well until I started milling out some PCBs (milling the copper off the board). Since I'm working with small cutters, a lot of gcode is generated (getting close to a thousand lines) and there's a lot of fine movements of the mill as it's cutting away the copper.
I've noticed that if I run the same gcode a second time, everything that is milled is offset in both axis.
So I'm thinking that my backlash may be off by just a little bit, but after thousands of fine movements the backlash error gets multiplied?
Is that true?
If so, what's the recommended way to measure backlash? Cycle one axis back and forth a lot of times to get an average backlash?