If you know the leadshines, I have seen, they offer a microstepping of 1000, 2000 and so on.
Do you know, if this works good. My machine have at the moment with 400 Mikrosteps a resolution of
1/100mm or 0,4thou. I must determine, if its metric or inches, But because all screws are metric, I hope the spindles are as well. With 2000µstep, I'll get a resolution of 1/1000mm that should be much better, if I want to make a real circle, or a tight fit.