You Gotta See This

[XYZADave]

Just when I thought I'd seen just about every variation on a drive screw,,,,I come across this! I can't offer any teckno discussion (I'll leave that to those who can handle it) Just thought it should be shared.

http://66.196.80.202/babelfish/trans...ntVictorSendas

Enjoy Dave

[nate]

wow. interesting...

[Khalid]

Wow.. Wow.. This is called Out of Box thinking...

[Sparky Marshall]

This looks great for light loads. Virtually no backlash. You could machine an insert for the inner race to insure good thread ingagement and fit.

[mc-motorsports]

I like it. I think with a little prefection via trial and error, we may see this in mainstream in the near future.

[Al_The_Man]

Rolling ring mechanisms have been around for a long time,
http://www.techna.co.uk/uhing.html
This takes it one step further to avoid the possible slip effect you can get with high loads using the traditional type.
Al.

[Geof]

Originally Posted by Sparky Marshall This looks great for light loads. Virtually no backlash. You could machine an insert for the inner race to insure good thread ingagement and fit.

With your insert and the bearing mounted in a type of gimbal so it could be spring loaded into the thread there should be no backlash and quite a reasonable load carrying ability. Most acme thread with the diameter needed for stability and the lead needed to get acceptable rapid rates are many many fold stronger than needed for the loads imposed even during acceleration. If this design gave only 5% of the normal load it could still be a few hundred pounds force.

The only negative point could be the bending moment it puts on the screw, this could rule it out for small diameter long screws. However, this same bending moment could stress the screw and minimize whip at high speeds.

[Mike Everman]

Yep, very nice. Good to see someone using that in a practical sense. I don't know how many times I've played with that in my hand, there being bearings and screws all over this place. I went down the roller screw path to get out of that moment load on the screw.
Super neat, though.

[chinsettawong]

Good idea!

[LeeWay]

Good stuff. This will certainly bare more testing.

[Arquibaldo]

I am feeling quite dumb. I tried very hard to imagine how this contraption
works but failed, yet everybody seems to get it...

I even went to the original site and found several other drawings and pictures
of actual implementations:

http://cncloisirs.com/Construction/E...ntVictorSendas

but I still cannot see the light - does the inner race of the bearing slides
over the Acme thread? If it doesn't, I cant see how the bearing can move with respect to the screw. But if it does, it seems to me there would be
a lot of friction and the thread would be quickly deformed by the hardened
bearing race???

Please, can someone who understands this thing try to explain it very slowly
to me? I am very excited by this approach, since the french site describes
it as a "poorman's ballscrew", extremely efficient and virtually backlash-free
- it seems too good to be true.

[ger21]

The inner race of the bearing rests in the threads of the screw, and when the screw rotates, the inner race rotates with it. The outer race of the bearing is locked in place.