Steppers are definitely strong enough. The NEMA 42s on my machine are geared down 10:1 and work very well moving a 100ish pound gantry. The issue with gravity

Steppers are definitely strong enough. The NEMA 42s on my machine are geared down 10:1 and work very well moving a 100ish pound gantry. The issue with gravity is not really motor strength so much as it is rigidity. There is no z axis rigidity in the setup because it only has a chain. So it can't exert pressure against the material from the axis. The lack of rigidity is the real problem. As mentioned in other parts of this thread, .01" accuracy is not going to give you great tolerance for pieces where that error can be cumulatively compounded.