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View Full Version : Long X-axis methods: Rotate the nut?



OCNC
11-23-2004, 09:35 AM
Has anyone ever seen or tried a rotating nut on long axis lead screws?
A rotating nut would eliminate the problems of shaft whip. It would also allow the use of thinner and less expensive screws (or the cost difference could be applied to purchasing higher precision screws).

Chris

jcc3inc
11-23-2004, 11:28 AM
Dear Sir:
Why not consider rack and pinion as the drive means. Use 20 degree pressure angle pinions and rack, use more than an 18 tooth pinion, spring load the pinion into the rack.
We used them on all our plasma and oxyfuel cutting machines (up to 16'wide)
Regards,
Jack C.

Moondog
11-23-2004, 02:40 PM
Has anyone ever seen or tried a rotating nut on long axis lead screws?
A rotating nut would eliminate the problems of shaft whip. It would also allow the use of thinner and less expensive screws (or the cost difference could be applied to purchasing higher precision screws).

Chris

I have seen several of these in action, impressive speed and accuracy. usually they have 1 Ballscrew per side for longer Axis around 3 metres or longer. One particular a friend has set up in his business uses 2 ballscrews with spinning nuts. He has it set up that the ganrty travels 1 inch for every revolution of the motor. It is fast an accurate.

Even a large screw such as an inch or larger will sag over a 3mt lenght. What they do is have a couple of spring loaded arms that support the screw and fold down when the Nut passes.. Very simple actually..

jcc3inc... is right about the R & P for plasma tables because they have no cutting forces that a router is subjected to and therefore unlikely to jump cogs etc.... I would use R & P for Plasma machines.

The Dual Ballscrew and spinning nut is fantastic...It is what I'll use for any more machines I build. Fast, accurate. Should be able to do it for around $1k per side.

OCNC
11-23-2004, 04:52 PM
I have seen several of these in action....


How were the nuts driven? Belt? Gear? Other?

Chris

Moondog
11-23-2004, 05:13 PM
How were the nuts driven? Belt? Gear? Other?

Chris

They were belt driven.