[analogman]

I am doing an RF45 conversion (the real thing) - Do I need end support for the Y axis ballscrew? I am using 20mm diameter ball screw. The full length of the thread from the fixed end is 400mm. The length of the screw unsupported would be about 340mm at the extreme front. With this diameter and length be an issue for whip? Or can it be unsupported?

thanks

[vertcnc]

My RF45 conversion uses a 20mm screw on the Y axis. I didn't use end support on this axis, but did on the others. Haven't noticed a problem.

[analogman]

thanks. It will help with a touch more travel.

[Fastest1]

Personally I would go for the support. Higher speeds (if desired) will cause whipping of the screw, especially if the axis is at the far extreme leaving most of the screw unsupported.

[vertcnc]

Yes, Ideally that would be the way to go. The screw has about 10" or less unsupported, so probably wouldn't be an issue. Not much for good mounting surfaces on that end of screw. The other way to go is mount the motor on the column end of y axis and support the front.

[pippin88]

Nook (I think it's them, link is on Google and the zone somewhere) has a ballscrew whip calculator. If it is not going to whip at the rpm you'll use then leave the end unsupported.

[embraced]

This link is the one pippin is talking about. Nook Industries Engineering Tools

Scroll down until you find 'Metric/Inch critical speed'

Using this I got a max speed of almost 5000RPM using an unsupported length of 400mm (and a root diameter of 18mm).

[analogman]

Thanks for the links. Since my max design is for 200IPM to 2005 ballscrews, this would only be 1000RPM, 1/5th of what Nook say is max for this type of ballscrew. All is well.