Hi John
thanks for the help. I just tried 320 in the steps per box and that gave me 2mm per unit of X. 160 gives me 1mm per unit of X.
the stepper driver is def set to 800 and the ball screw is 5mm, direct drive from a 1.8o stepper.

The motion at 160 is rough but I will tune it tomorrow, but would be interested in your thoughts as to why the math did not work out.
cheers
joe