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Planetary Roller Screws

submitted by happytoes to Machining 4 monthsDec 14, 2023 19:11:23 ago (+10/-0)     (www.youtube.com)

https://www.youtube.com/watch?v=mCz9Vaw3NL8

I've got a small manual lathe that I bought second hand. My father taught me the technique of taking up backlash. When you need to move the top slide out, to increase the diameter of the cut, move it too far, then screw it in to the required setting. This ensures that every setting is set pushing the top slide in. This technique works, but is annoying. On a worn old lathe it is essential.

But how does modern CNC machinery work? It seems to zip back and forth by turning the lead screw, with out regard to backlash. I think there was a short era of using two nuts, held apart by a strong spring that both takes out the backlash and creates lots of friction. Then came recirculating ball screws. The rolling of the ball bearings solves the problem of friction. Accurate manufacturing of the ball race helps, and finally backlash is eliminated by having the nut done up tight.

Then I saw this video, which looks like it is the next stage, with all the baby thread rollers rotating around the lead screw. They claim repeatability of 0.006mm. I guess this is the possible error between screwing in and screwing out to your setting. I'm not involved in this technology, I just like to watch and keep up to keep in touch with how things work.


4 comments block


[ - ] x0x7 2 points 4 monthsDec 15, 2023 00:48:12 ago (+2/-0)*

I don't understand how companies have the finances to put together these animations but not the finances to hire a voice actor to read their script.

I guess the models are free because they already had it in CAD. But you still had to use up a valuable worker's time to make an animation that lines up with the script, and write it, and edit it, and buy stock images. I'm guessing that video cost about $200-$300 in extra labor to plan and produce. A voice actor to read a 2 minute script is $5 on fivver.

And then you don't sound like a bunch of Indians trying to hide behind text to speech.

[ - ] uvulectomy 1 point 4 monthsDec 15, 2023 02:20:17 ago (+1/-0)

"Planetary roller screws the best performing drive system among known screws are the best."

Well I'm convinced!

[ - ] germ22 1 point 4 monthsDec 14, 2023 22:46:19 ago (+1/-0)

Most CNC machines these days can take up backlash in software as well. Generally something in the machine parameters not easily accessible by the operator.
It's a neat video you posted, first time i've actually heard of this tech. I wonder how sensitive it is to dirt ingress.

[ - ] happytoes [op] 0 points 4 monthsDec 15, 2023 11:13:38 ago (+0/-0)

I would guess: very sensitive to dirt ingress.

But I make the same guess for recirculating ball screws, so I would make a third guess: just copy the seal technology from the ball screws