Thanks for the quick response...

I am doing a CNC conversion on a Warco WM16 and I'm following Hoss's design (more or less) I've had the screws machined in China but they neglected to put a thread for the Ballscrew retaining nuts on the Y axis... with this plan the 1605 screw is reduced to 10mm for bearings and then tapped at M10 x1.5 and finally reduced to take the motor coupler...

Hadn't even considered squareness to shaft...