Newbie (ageing rapidly!)

[ManicMetal]

You're right 2.5mm pitch screws.
I've already had the X and Y drives running (from a signal gen) up to about 60kHz (2800mm/min on 16 ustep) Where the power supplies run out of voltage to drive the 2.8mH inductance. I loaded the bed with my heaviest vice, and angle plate.

It isn't a matter of resolution 8 ustep would give me 1.5um resolution (way more than the tolerances of the machine) but 16 ustep does give a noticeably smoother motion than 8. There is hardly any reduction in torque (this is more a factor of adequate drive voltage). I've specified 2000mm/min at 16 ustep to stay within reasonable rpm for the motors while keeping to a frequency the motion controller should be capable of, I can always reduce this if needed (commissioning trials will prove the limits and determine the maximum ramp rates).

I'll take a look at the Acorn system, seems a shame to abandon Mach3 and Mill Wizard, I like their simplicity.