8x4 Wall Mounted; Upright ply cutter

[charlieuk]

So it's posable to do a 8' ball screw with out a rotating but but you are just more limited with speeds?

[Clive S]

So it's posable to do a 8' ball screw with out a rotating but but you are just more limited with speeds?

I would say so but it would have to be a greater diameter and therefore you would need bigger motors to drive it etc. But wait for the tech boys to chirp in ..Clive

[JAZZCNC]

I would say so but it would have to be a greater diameter and therefore you would need bigger motors to drive it etc. But wait for the tech boys to chirp in ..Clive

First prize to this man.. .

For 8' your into 25mm screws minimum and has clive says motors & drives to match. Thou Charlie you are familiar with the motor/drives already as they are the Nema 34 and high power Kinco type you are using now.
What you can do to help ease screw whip is use higher lead on the screws and put ratio on them. So say 20mm pitch with 2:1 will give you same feedrate as 10mm pitch but with half the RPM on screw so helping to eliminate whip etc.
If for wood use then 25mm screws with 25mm lead and 2:1 ratio would work well as it will give decent feedrate/resolution for wood and suit slower spinning nema 34 motors better.

[Jonathan]

Charlie, have you read the threads here and here? That should answer your questions.

The critical speed for an 8' 25mm ballscrew is about 370rpm, so if 20mm pitch you'd get 370*25=7400mm/min, which might be acceptable. With a rotating nut maybe twice that.