Not exactly DIY ballscrew: ServoNut

[Mike Everman]

Not really a plug, though I do make these. Just proud of how well they work, and wanted to share with you guys. Even in a DIY CNC, the technique is not too much more effort to belt drive your nut.

Main advantages are:
1. Extreme low inertia. You can use a smaller motor for higher accelerations.
2. High speed limit. There is no screw whip.
3. Superior lube retention. Grease is centrifugally retained in the nut's grooves. We ran one of these making 300 lb accel/decels, 25mm moves, 20 ips, 24/7 for two years and never had to re-lube it.
4. Multiple carriages can run on the same screw. How about driving your lathe tailstock, too? ha

These are too expensive for most, but I'd be happy to help with a DIY approach.

Best regards,
Mike

[d.dixson]

That looks pretty awesom Mike. How the heck...? Do you have a website? Diagrams?

[antichip]

Is this like a hollow shaft servo with the nut included in the shaft? That would be an awsome upgrade to the mill plans.

[Mike Everman]

Hi. My website is in my profile.
Yes, it is a hollow shaft 3-ph servo motor set, NEMA23 triple stack.
We build up the unit with a single duplex pair between the nut and the motor rotor, ABEC 7-9, ground for back to back preload, so no thermal issues that one might have if the bearings were far apart.
Here's a video (man, 500kb is not much space!) of one doing 2.5 meters per second, which is the limit for spinning this ballnut.
I've seen sub 5msec settling times with a 150 lb payload on the 10mm pitch with the same motor.
The screw is an internally preloaded Bosch-Rexroth precision rolled. If you ever see their screws for sale, grab 'em. I can't recommend it highly enough. Purely the best screw for the money.
Hmm, that didn't come out right...

[rokag3]

Here's a video (man, 500kb is not much space!)

you ca use youtube and add a link
that's fast !!!
why not use your design as described in

http://www.cnczone.com/forums/showpo...&postcount=298

to do it ?

[Mike Everman]

Originally Posted by rokag3 you ca use youtube and add a link that's fast !!! why not use your design as described in http://www.cnczone.com/forums/showpo...&postcount=298 to do it ?

Sure, that is a natural progression for this. The roller screw would be simply balanced if there were four bearing subassemblies, two between two...

[Conrad_Turbo]

I'm going to bump this OLD post up. I have salvaged about 4 axis' in total from two x-ray machines and had no idea what they were until I found your site Mike Everman!

Here is the thread I started.
http://www.cnczone.com/forums/cnczon...build_cnc.html

What electronics do I need to drive these servo motors?