CNC Woe's

I have a microkinetics CNC lathe and am having a calibration problems.
Every time I do an inside Dia cut operation my (X) looses its position.
Now the setup is tight and not moving and the motors shafts appears to
be nice and tight where conected to the motor. The (X) moves nice and
smooth but my ID keeps going up for example 15.00mm to 15.02mm every
operation it performs. That adds up quickly. Can anyone aim me in the
right direction. The last time I talked to the manufacture they focused
on my G code for the loss in calibration. Since I am using mostly G01
commands I hardly think this is the problem but I could be wrong. If
anyone could help I would appreciate your comments or PM.


Harry Siebert