Gaspard de Coligny wrote:For the proxxon tolerance... at this point 1-2mm would be awesome... how can you make repeated pass without going back. If i repeat my x passes i always clear 1 mm on y when pulling back. with the backlash as it is it's like having to reposition the stock for every pass...
Even if you go back and forth but are always cutting in the same direction (i.e. you're only backing up to make another pass) it should be pretty accurate, since you're always pushing the bed with the same edge of the screw (assuming your bit is rotating in the right direction re. the workpiece). If you move to the other side of the workpiece to cut in the opposite direction you'll need to recalibrate.
I don't know how complex your cuts are, but for basic straight cuts, one at a time, it's not a huge problem.
I know some guys have added feed motors and CNC control to those Proxxon mills, and I can't see that working very well without some serious modifications to the bed.
EDIT: By the way, 1~2mm is way too much. That would have to be more than just screw backlash. If I remember correctly mine is about 0.45.