When cutting a 5"x5" square my machine consistanly cuts two sides on the Y axis perfectly at 5" and 5 1/16" on the X axis sides. What could be causing the x-axis to repeatedly go over by 1/16"? When each axis is tested individually with a 1" dial indicator both are within a + or - thousandth or two. The repeatability seems to be very good.

I am using CNCRouterParts Rack and Pinion on both x and Y axis. The X axis is dual driven by 420oz steppers. My power supply is 36V 8.8amp. I am also using a gecko 510 board.

Any help will be greatly appreciated.