[bowtechmatthew]

When I tell my CNC Mill to move .5 of an inch on the X Axis in the Axis Calibration it moves .5 of an inch so it is calibrated, but when i tell it to move .5 of an inchon the X Axis on the MDI Manual run it only moves .455 of an inch. What is my problem?

-Matt-

[awerby]

It might be backlash. That's due to the space between where the nut engages the threads on one side, and where it engages on the other, when it changes direction. To check this, make two measurements, going in the same direction: command a move to .5", mark that position, and then, going the same way, command a move to 1". If backalsh was the problem, the second set of measurements (from .5 to 1.0) should be correct. If it's not, then you've got another problem, like slop in the bearings supporting the screw, a loose connection, or an inaccurate screw.

Andrew Werby
www.computersculpture.com