Hi all,

The problem:

My PCBs mill larger than they should be. Footprints for ICs are not useable as pin spacing is too big. (what should be 0.6mm spacing is about 0.7mm).

My setup:
Microcarve MV3
Gecko G540 c/w 3 x Keling 381oz motors
XP PC via Parallel Port

Workflow:
Eagle > PCB-GCode.ulp > PCB-Gcode Wizard for tool path optimisation > Mach3

What I have tried:
Digital caliper fitted to bed of CNC for axis calibration. Enter 10mm and enter measured value, this was repeated until I get an error of +/- 0.02mm on each axis.

My thoughts are, using Eagle to create a calibration PCB. Horizontal and vertical tracks, 10mm length, then measure these after cutting and enter the numbers into axis calibration, that should work and calibrate the machine to Eagle output.

Am I chasing the wrong issue here, or would you suggest I look at something else?

Thanks a lot.