Rotating Ballnut - design ideas

[Jonathan]

Hi Jonathan,
have you seen these bearings, which are meant for the purpose?

No, I hadn't spotted that. I see they've used bearings with a higher contact angle than most angular contact bearings, as that allows the bearing spacing to be lower for the same stiffness. I don't think this is too big a concern with the rotating ballnut bearings, as they are oversized compared to the bearings one would use if spinning the screw.

I've just finished making three more rotating nut mounts for someone who spotted the video on YouTube who's making a large machine with two SFE2525 ballscrews and one SFU2010 ballscrew. I simplified the design by changing the housing for a block machined from 4" square aluminium bar, and a separate piece cut on my router for the motor mount.


Some pictures:




A video, feedrate displayed assumes connection to 25mm pitch ballscrew:



Drawings:

RotatingNutSimple.zip


Feel free to copy or modify the drawings and use them to make your own or get the parts machined by your favorite company... I don't mind.

[Clive S]

Very nice indeed Jonathan, I can see a lot of work has gone into those. ..Clive

[paulus.v]

Hi Johnathan,

nice work! I have a question: How did you fasten the pulleys on the rotating ballnut shaft and motors?

[Jonathan]

Very nice indeed Jonathan, I can see a lot of work has gone into those. ..Clive

Thanks, yes they take forever, or at least it feels like forever when you're only able to machine things at weekends. It's been three months since I agreed to make them.

How did you fasten the pulleys on the rotating ballnut shaft and motors?

M5 and M4/M5 grubscrews respectively. So long as you threadlock them it works. The reason I didn't use a clamping method is that tends to require a larger diameter pulley, particularly on the ballnut shaft, which would increase the moment of inertia.

[Lee Roberts]

Feel free to copy or modify the drawings and use them to make your own or get the parts machined by your favorite company... I don't mind.

Thanks for the share JB, ok to put this in the Open Source section?

.Me

[cnctom]

No, I hadn't spotted that. I see they've used bearings with a higher contact angle than most angular contact bearings, as that allows the bearing spacing to be lower for the same stiffness. I don't think this is too big a concern with the rotating ballnut bearings, as they are oversized compared to the bearings one would use if spinning the screw.

I've just finished making three more rotating nut mounts for someone who spotted the video on YouTube who's making a large machine with two SFE2525 ballscrews and one SFU2010 ballscrew. I simplified the design by changing the housing for a block machined from 4" square aluminium bar, and a separate piece cut on my router for the motor mount.


Some pictures:




A video, feedrate displayed assumes connection to 25mm pitch ballscrew:



Drawings:

RotatingNutSimple.zip


Feel free to copy or modify the drawings and use them to make your own or get the parts machined by your favorite company... I don't mind.

Very nice design what size pulleys did you use i'm looking into building this myself but want to be sure to order the right pulleys and belt thanks for your time and engineering.