BB King - the 3D Printed Roller Bearing

by Mr_MegaTronic, published

BB King - the 3D Printed Roller Bearing by Mr_MegaTronic Jan 26, 2013

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Is friction giving you the blues? BB King is here to help!

This is a proof-of-concept print to evaluate using standard BB bullets as the rolly bits in a 3D printed bearing. I'll be using what I learned from this in some projects I have coming up!

VIDEO: http://youtu.be/3pl6-AXtWZY

I'm using 6 mm plastic BB bullets and I printed my prototype in ABS at .1 mm layer height, 10% in-fill and with 3 shells on my original Replicator.

I had to scale the model up a hair and that is reflected in my THING file. The STL files are original scale.


If you like what I do and want to help me do more, please consider supporting me on my Patreon page! http://www.patreon.com/ErikJDurwoodII Thanks!


Print - you may have to scale up the model if you don't use my THING file or you have a different size of BBs.

Load - Fit as many as you can leaving one out to fit the key in.

Lock - slide the key in to long the bearing tight.

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This is a ball bearing, not a roller bearing. But it's very nice, regardless :)

Why did you put it vertically.. Ah well admesh --x-rotate 90 it...

Works surprisingly well. Nice design!

Have you thought about making the key in two parts, fitting one key part in from each side and having them snap in or perhaps permanently gluing them in place? I think this might allow another bb to be inserted.

Why the HELL is that Featured?

it would be nice if you made a version that had a cage for the bearings too, that would improve efficiency.

I'm looking at that. I want this to be something that could be printed "wrong" and have a chance at being somewhat useful. At the scale of this, a cage would have to be printed along with the inner and outer race and the print paused just after the mid-point to load the bearings (like toni1727's derivative) and then be enclosed bu the rest of the print. I think a greater diameter bearing would work well for this. I would just have to have the cage be "forgiving" enough to print alright with the many printers out there.

also this would scale up nicely, i think im going to use this to attach around some aluminum extrusion

This is very nice. Two tips for people printing this:

  • 4.5mm BBs are quite common. This is designed for 6mm BB's. If you scale this by 75% it'll fit 4.5mm BBs.
  • The easiest way to fill it is to first push the 'key' into place, then pull one end back so that you can drop the BBs into the proper place one at a time. I wasted some time trying to put the BBs in before I figured out this trick.

Given that, one suggestion for Erik - you should put the bottom half of the 'key' back onto the inner bearing, so that only the top half of the key is missing. That way you can put the BBs into the bearing exactly as it sits on the build plate, then when it's done you can slide in the 'half key' to plug the hole and complete the bearing. I don't know that it's easier than the "push the key in and pull one end out" but it's more obvious.

Thanks for noting that, i'll check the BBs first then i suppose. Also it'd be nice if the bearing size matched existing bearings.(so it can be used as a replacement... if the requirements match.

That is a good suggestion! An earlier version of this I printed only used "half" of a key but the issue I had was due to the size of the print, the displacement of material (which varies with different printers and print settings) made the channel too snug and I had to relieve a lot of material to get it in. This design uses the flexibility of the plastic to have a bit of give to allow the key to wedge itself in without needing any relief after printing. This also minimizes the extra ridges inside.

Still I would like to fit that one last bearing in and a half key would allow for that. I didn't print the other design at 100 microns so maybe I can try that.


Interesting - I hadn't thought about the 'key' forcing the inner bearing to enlarge to lock into place. Makes sense, though.

Once trick I've used to accommodate fit between pieces is to have little bumps or ridges in one of the pieces, which can get squished down to fit the other plastic. This is more forgiving than having both pieces smooth, where fit needs to be more exact.

Thats the way to go. Printed ball bearings need to be post assembled to have a nice tight fit. Only a cage is missing - but then how do you get the last ball in? Makes me wonder how steel bearings are filled.
ps: Compliments to the nice front image.

Thanks on all counts! Yeah 6 mm is pretty much the standard. Though there is variability in the actual product. My BBs measured to be on average 5.8 to 5.9 mm or so. The bearing is nice and tight though, not really any lateral shift and I didn't add the last bearing as it would have not added really any extra surface for rolling though it would make it a tad quieter.

I wanna roll, roll, roll forever
I wanna feel the beat go on

Nice work man :)