Gallery, Projects and General > The Design Shop
3D Printed Ball Nut for the Insane
DMIOM:
--- Quote from: Joules on August 19, 2016, 12:19:03 PM ---........Graunchy start and see where it goes from there. .......
--- End quote ---
Where next - :proj: - if you find that FDM doesn't give a smooth enough ball raceway, then obviously the next step is to upgrade the printer - some sort of selective laser sintering unit? :headbang:
Dave
Joules:
That would be robot arm operated MIG welder then.
Joules:
I finished up the nut design this morning. I like little exercises like this as they make you think and keep the drawing skills sharp.
I took the sectioned nut and made a start on the recirculation path for the balls. The balls have to come off, and return to the ballscrew at the helix angle, I also added an incline of the same angle to increase clearance over the existing raceway in the nut. The pipe command is used on the curve I generated and a good radius for the bends.
This is the internal raceway once I have cleaned up the nut of the excess raceway exiting the nut and combined the pipe we added earlier. The raceway has also been trimmed where it breaks the surface of the nut.
So we end up with a basic nut like this, with the exposed raceway where we can load the balls later. Finally for this part we need to cap that open raceway.
The cap is nothing fancy, but having a flat face helps printing it later.
Here we see the finished components, the cap had a lip extruded round it and trimmed to take a matching cut out of the nut for alignment and gluing in when the nut is assembled. The pipe we drew earlier was used to trim the raceway in the cap. The nut is stood vertical ready to be printed with the cap at its side.
In all honesty as a printed part this just wouldn't work. I would need to add clearance to the raceway in the nut for the balls to move, the error in my printer layers would most likely mean the raceway at one end won't line up with the raceway on the ball screw. However it has given me insight into how a nut works and can be designed, much respect for the companies that make these things and the precision they achieve. If I happen on a bag of 2mm BB's I may have a go at printing this with some tweaking of the tolerances to line things up. My thoughts are as the ball screw is hard it would peen the soft nut raceway into a good surface, not sure about the raceway tube, that might need to swell a little to allow free movement without too much bunching.
I'm still pretty chuffed that I managed to draw up a reasonable model that I feel would work and write up the results here in just a few hours. CAD is all about doing, making virtual swarf.
For those curious to take a closer look I have just posted an STL file on GrabCad
https://grabcad.com/library/3d-printable-ballnut-for-1205-ballscrew-1
Please add a LIKE if you download it. :thumbup:
awemawson:
Pretty darn impressive Joules :thumbup:
DMIOM:
+1 :thumbup: :clap:
Dave
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