Hi Bob,

A couple of thoughts... for 1500mm span, 1200mm/s is far too low, thats over a minute to get from one end to the other. Since screw inertia is the major factor on a screw that large you need to use a higher linear speed to ensure your motors can give you reaonable rapids... say 3000mm/min, you wouldnt cut at that speed but you need some headroom, you can reduce the acceleration to 0.1 for rapids calculation. Secondly, although it won't affect your motor choice, use supported-supported on a screw of that length and diameter - always worth spending more to get the mechanics right.

This gives you a motor needing about 10W output.. A suitable motor would be SY60STH86-3008BF (3Nm NEMA23, 3 stack) on 40v/4A drivers, wired bipolar parallel. You could go for a smaller motor on Y and Z