hi,

i just looked into using timing belts and pulleys for my x-axis and have decided against it, i too wanted to mount my motor above the x axis instead of having it stick out over the end. They're pretty easy to set up and fairly inexpensive as you've probably seen, but by all acocunts, and this comes from a friend who has built quite a few of them, not the best of choice if you're using a ballscrew as your drive mechanism, since you are going to lose the accuracy gained by having that kind of scew. couplings are probably your best way to go, at least if mega accuracy is what is needed.

saying this though i'd still be tempted to give it a go , being the inquisitive type.. apparently the T5 Polyurethane betls are the way to go, but again who am i to know. good luck. have you made uo your mind yet to go ahead with the conversion?