hiii i built a cnc router ,i used rack and pinion for the x and y with gear ratio 1:5 and ball screw for the z with gear ratio 1:3 i am ysing a dsp hand controllrer the problem is the distance moved by the machine is not exact like the drawing it is as if it is scaled larger by 10%...there is a setting in the dsp hand that requires a parameter which is the no of pulse needed to move the machiene 1 mm pulse/mm so i guess there is a formula for rack system and another for ballscrew to calculate this parameter..thnx