Re: Rotating Ballnut

Marcus,
You are right about the cost of commercial rotating ballnuts. I was
thinking of rolling my own. Seems like you could use a zero backlash
nut mounted in a tube with angular contact bearings on the ends.
Mount a timing belt puley on the tube and clamp the bearings to the
table and you have a rotating nut. I don't think it would be much
more challenging than builing a spindle. What I don't know is if a
standard ballnut can be spun. I'm assuming that they aren't anything
special. They only need to stand up to a couple of thousand RPM.

I agree with the need to tension the ballscrew. I guess you just
have to design for it. Cabling is always a pain. I'm planning on
using steppers (first time) so I won't get run aways like I do on
the servo mill if a cable gets unplugged.

Mach3 has the ability to do screw mapping which can compensate for
inacuracies in rolled screws if you have a way to measure deviation.
I've got no good idea on how to do this but the way things are going
it might be next spring before I start building.

Roger

> Are you sure that using a rotating ballnut will work out

cheaper than a

> decent sized screw?
> Last time I looked, rotating ballnuts were horrendously expensive.