So far I've been thinking direct-drive for the conversion of my PM-932M, but I really like JBolt's implementation with timing belts for space-saving. From what I've been reading, timing belts introduce another point for backlash, but there are trade-offs with everything. What's the thinking on the type of belts -- I see on McMaster-Carr they come in various "weights", from XL (Extra Light) through H (Heavy) to HTD (High-Torque Drive). I've ordered the same stepper motors as JBolt used on his conversion (2 Nema 34 1600 oz.in and 1 Nema 42 I forget the torque). The L series belts come 1/2" wide and up while the H series start at 3/4" wide, and the stock ones start fairly long while the L ones can come somewhat shorter. None of them are terribly expensive. I'm looking at ball screws that are nominal 5/8" (approx. 16mm), which would need to be turned down to 1/2" , which is the size of the L-series pulley , whereas the H-series pulley starts at 5/8" diam. Do you think the L-series belt would be heavy enough for these motors?