Homebrew PCBs

There is another point where i have questions...

Which motor power is needed? (i know this depends on the loading of the 
machine).
But i mean in general..

Also i wonder how many motors are needed, for the main axis, if you move 
the
workpiece in one direction, you can use one with a centered threaded rod.
but if you make the spindle move all three axis it can't be in the middle 
(it would opstruct the spindles movement).


What is better, using two motors and two threads, two threads belt coupled 
and driven by one motor?

What if one decides to built the centered drive under the moving workpiece, 
if the milling
it at the very side may this not cause the carriage to twist?



the other axis are pretty clear, one motor can be used and the driving 
thread is not in the way of the spindle.



I have lots of steppers here, but they seem to small for me (maybe one for 
the z axis....).

Any power rating on actual machine would be fine (think steppers are 
labeled volts and ampere).


Thanks
Stefan