Did you do the calculation to take into effect the 30:1 gearbox or just the 3.1Nm motor
I definitely only accounted for the 3.1Nm motor. I'm awesome like that. I will certainly consider that motor and gear box, though I have been looking at other CNC motors. As far as finding parts in metric - I can do that easily; however, I'm the only one who wants to use metric in the lab/shop/office here so I will have to continue posting odd measurements. When I do my own arduino project, then everything will be metric and it will be beautiful (seriously, who would willingly measure things in fractions rather than decimals).
wwbrown: We have looked at digital linear scales, but we haven't found any that could get the resolution we are looking for. If we were to go that rout we'd likely stick with an LVDT. As far as a linear actuator - that's not something we've looked at. I'll do some research into them, we would need one rated for the force required that allowed for minute adjustments.