[cboyce]

I've noticed on fine detail work, the table on my fixed gantry mill is slightly uneven. For most parts this isn't a problem, but one thing I'd like to use it for is PCB etching, and so the vertical tolerances need to be pretty tight. Since I can fairly easily measure the amount I need to displace the Z position just by jogging and touching around, is there any way in Mach3 to compensate for this? I was going to make a script which automatically transforms the coordinates in the gcode, but I'm hoping for a more general solution.

[MyCattMaxx]

There are some threads on touch probing, but if it were me I'd make a pcb fixture and make it level by surfacing.
Just remount the fixture in the same spot every time you use it.
Or I would work at leveling the table.

[cboyce]

The fixture is a great idea, I think that will be the easiest way for me to go. This is my first attempt at a home made CNC mill, and since everything is held together with wood and screws at the moment, fine-tuning the table level would probably be difficult to do with any accuracy. Thanks for the quick reply!

[MyCattMaxx]

There is a thread here somewhere that someone made a nice fixture with a recessed area the pcb fits in to. He also had a spot along the edge that you could get at the side of the pcb for removal.

[ger21]

Surface your table flat with the machine.