Hi Jazz,

On the datasheet for the motor is said 6.2A (phase) which I take to mean each winding will draw 6.2A. So if I wire in parallel it will draw 12.4A. In series will will need about 3A but twice the voltage. Won't it?

Each side column of the gantry rides directly on the centre point of the linear bearings, and I was going to use solid 12mm alu sheet as a cross-brace underneath. In that case I guess maybe a single central ball-screw with a powerful motor would be okay. However you point that a nema 34 spins slower is worrying as I want all axis to be capable of the same speed. What do you think, is it okay to use a nema 34 only on the Y axis?

Why is running two motors from one controller not a good idea? Provided it can output the required current and voltage it should be okay, won't it?