Gallery, Projects and General > The Design Shop
3D Printed Ball Nut for the Insane
Joules:
Ahhhh, inspection time showed up a couple of flaws. I had been stuffing balls in to reduce the gaps, still had about 1 balls worth of gap and I noticed the ball nut has started cracking. Fair dues, it's not much thicker than 1mm at the thinest points between shell and outer, and it was designed rapidly last night as proof of concept. I could print thicker shells as this is pretty thin, increase the raceway clearance a gnats or machine an alloy case to clamp the nut externally. That last option isn't a bad idea as the nut becomes an insert that is easily replaceable. Not quite an all printed solution though. I have printed a second nut and taking extra care to prepare the internal raceway and scrape away as many fine blobs as I can find as I guess the pressure inside the nut must get pretty high as it's bedding in.
The cracked nut does feel smooth and still no backlash, time to pull it apart and inspect the raceway internally.
The nut internally is quite badly contaminated with PLA debris forced out of the raceway. It was soft enough you didn't feel it, but I need to find a way of burnishing the race before assembly. this nut is being cleaned up and I will carry on testing it. The count was 74 balls in this nut, so thats about 150mm of raceway wrapped inside this tiny nut. Need more balls for more nuts
Joules:
Problem solved with nut No. 4
It now has a thicker body by an extra 1mm, I was also able to increase the raceway separation to 1.5mm, from 0.7mm. The new raceway was increased to 2.4mm, like I said it should have been in the first place :palm:
The temperature I was printing at was the high temp I used for printing the shells, this was causing the extra blobs I was having in the raceway. The nut has had some running in on the lathe at various speeds to bed it in. The photo below was after the running, and no fuzz from the PLA, so it looks like the raceway got burnished properly this time. Printing more nuts for future use, and get some balls ordered.
Joules:
I figured I would print a window to show the balls recirculating and give some scale to the nut. This is the new revision 4 nut, whilst assembling the new window I fumbled the nut and lost 8 or so balls. I was working over a tray, but most of what fell out only a few inches above, made a mad bounce for freedom. The new nut has 84 balls in it, I am down to 5 spare as every time I open this, I loose a ball or two, or "8"
This has been a long time in the making, from those first drawings to not really believing this would work, to not an insane Ball Nut anymore. I will carry on refining this design and try to find a worthy project to make use of them, or see if anyone else runs with the idea.
awemawson:
Looks excellent Joules, do you have a real life application for them, or is it just the joy of achievement that floats your boat?
Joules:
Design looking for a purpose. I had an idea in mind but ball screws and commercial nuts put the project outside my play money. I did still want to know if I could design and print a working version. They might make a good alternative to belt drive or get a small desktop cnc working again. I ordered some more balls, I should really print one and set it up with a thrust bearing then torque the ball nut to destruction. I might also have come up with a serious use for IGUS filament.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version