The X axis ball screw would need to be 1600mm long and the Y axis (gantry) 1500mm long. I was hoping to use 10mm pitch screws, so it seems your limited to either 16mm or 25mm. Whip is a concern.

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The motors are the Nema 23’s on ebay from CNC4YOU and appear to have a low inductance and 4.0N.m hold torque, but I don’t know if that’s enough and what I’ll actually need.

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Are there any simple rules of thumb to work out your requirements regarding motors and screws?

And one word of advice for anyone designing a machine, make sure you have lists and lists of standard size materials. I have gone through the pain of having to redesign this because I didn’t check on the sizes of steel or MDF. “D’oh”