Rotating Nut Fixture x2

[komatias]

Boys,

if we can get the numbers, I could assist in getting this off the ground. I already have a compact and economical solution in mind.
My ballscrew suppliers are easy when it comes to low quantity special nut shapes so that will not be an issue.

If you wanted to go with the bog standard screws, and ballnuts that can also be accommodated.

The question for you will be what motor sizes you are likely to want.

[Desertboy]

3nm would be a good start point and I''m sure 8nm and 12nm would be sellers to.

I'm a 3nm kind of guy

[m_c]

I think Komatias meant frame size, not torque ;-)
I would expect a choice between Nema23, 34, and 60/80 servo sizes would cover most bases.

Until Komatias posted, I was thinking of making some of these, but I won't step on his toes.

[Desertboy]

I think Komatias meant frame size, not torque ;-)
I would expect a choice between Nema23, 34, and 60/80 servo sizes would cover most bases.

Until Komatias posted, I was thinking of making some of these, but I won't step on his toes.

If it gets me 3 rotating ballnut fixtures you can dance on my grave lol.

[Krammer002]

My personal requirement would be NEMA 34 frame size...

[komatias]

I think Komatias meant frame size, not torque ;-)
I would expect a choice between Nema23, 34, and 60/80 servo sizes would cover most bases.

Until Komatias posted, I was thinking of making some of these, but I won't step on his toes.

M_C

You carry on mate, personal circumstances have changed a bit so will probably be a while before I can take this project on now.
If you need design input or parts sourcing I can help of course.

[m_c]

OK, so just ran the figures based on Jonathan's design, and by the time you add up all the parts, you'd be looking a finished cost of over £200 per assembly to make them worthwhile making.
That would include the main assembly (Alu shaft, 30t pulley, sealed 7207 bearings), motor pulley, and belt.

However, that's not how I'd personally mount ballnuts , as that's not how they're meant to be mounted.
The precision surface is the external cylinder of the main nut, which should be contained within a hole, but to mount them that way involves scaling things up a bit, however with a bit of a re-design, it could mean they wouldn't need dismantled to swap belts.

[Krammer002]

m_c, Are you suggesting something like the housing shown in this design: http://www.mycncuk.com/threads/3340-...5724#post85724 but with the nut rotated so it sits inside the housing similar to this deisign: https://www.youtube.com/watch?v=4unEngqU09A
There also a GrabCad link to the design in the Youtube description...

[m_c]

m_c, Are you suggesting something like the housing shown in this design: http://www.mycncuk.com/threads/3340-...5724#post85724 but with the nut rotated so it sits inside the housing similar to this deisign: https://www.youtube.com/watch?v=4unEngqU09A
There also a GrabCad link to the design in the Youtube description...

Yes.

That youtube video is interesting, although they must be using an Rxx (cylindrical screw in) type nut, as the 3D file has a locking collar on the rear, which I can only guess is for locking the nut into the shaft.
Also, they must be relying on the pulley/pulley bolts to preload the bearings, which means you'd have to be very precise with measurements, or rely on shims for adjusting the bearings.

I need to go and sketch a couple ideas.