Hi all,

I'm building a small gantry (24" x 18" travel), that will move a super light load (~2lbs). I really need .002" resolution, but would like to get 0.001", and as many IPM as possible. For the Y-axis, there are 2 linear rails (one on each side), and I want to drive both sides simultaneously to prevent "racking". I'd going with belts, as I can use one stepper with a long shaft to both sides (eliminates out-of-sync issues if two motors), each with it's own belt. Ballscrews will get expensive as I'd need to get two, then use 2 steppers, two controllers, etc. This drawing shows one side of my game plan... http://tinyurl.com/yexcmg5

So now the calcs... as I understand it, microstepping will not let me get more resolution, but is just used for some smoothness between full steps ... is this correct? Or can I use say 1/2-microstep for a bit more resolution? Assuming I can't, each step will have to move the belt 0.001". With 200 steps/rev, each rev will be 0.001" x 200 = 0.2", which is now the circumference of the pulley. So that back-calculates to a pulley diameter of 0.0637" ... LOL!!! Even if I went for 0.002", that's a pulley diameter of 0.1275", so still LOL!

Plan B is to move the stepper elsewhere and use another pulley system to the long shaft to reduce the stepper motion. Is there a simpler way?

Cheers,
-Neil.