Hi,

I have done a few runs and sorted out momst of my calibration issues... But the one issue that is remaining (that I just can't work out) is a skew in the output... It is as if one motor is running at 1.2x the rotation of the other..

Attached is a sample output. Red indicates the page edge (sorry, photo not straight) and green is the drawing boundary. It should be square to the page.

The progressive dip in the top-left part of the picture is an unstable pen mount (which is solved already)

I have double-checked that the motors are mounted square and level (and one is about 1/2 mm higher than the other), and both have the same belt and pulley... Both motors are obviously the same model.

Any thoughts?

Oh, I may be able to answer my own question... The X measurement for the home point are in machine space, but the Y measurement for the home point is in surface space...

Ai ya!