I just set up EMC to control my mill. Everything appeared to be going well until I attempted to cut a profile with some arcs involved. Each pass of the contour results in a drift along my Y axis.

I believe I have eliminated backlash as the cause of the drift. I can drive the axis in a linear fashion (back and forth over and over) and the error is within .001". However, if instead of using a G1 command I use a G2,G3 command the drift appears. It's quite excessive! A circular command repeated 25 times can result in a drift of upto .125".

I think it's unrealistic that this is a bug in the EMC software. However, I can believe it is related to my INI file settings. Does anyone have a clue as to the cause of my frustrations?????

Thanks!

A bug is never unrealistic. If the arc is calculated with floating point instructions, the error can add up well, depending how the arithmetics are done. Have you done this test with excessive LOW speed?

Carel

I think you should post this on the emc user's list. Lots more good help there.