Planetary Bearing (608, 6001)

Boost Me If you love this model and appreciate the time and effort put into it, Consider giving it a Boost! Print Notes/Tips

Keep an eye on the first layer. Good bed adhesion is very important for a successful print.

The bearing has thin walls and each roller is a tiny separate part so it's easy for small sections to no get laid down properly which will lead to clumping and failed print. Adding a brim could help but would also add difficult post processing. But as long as you don't have bed adhesion problems and your filament is dry it should come out very nicely.

Traditional bearings are difficult to 3D print for a few reasons

- Perfectly round and smooth spherical balls are basically impossible to 3D print. - Print-in-place requires clearances between parts for everything to be able to move freely. - Plastic is quite slippery. This combined with the clearances mean that balls or rollers tend to just slide and not roll properly. Some designs are better then others

A few things other designs have tried in order to fix these issues is using rollers instead of balls. Which is an improvement because it can be 3D printed properly. And incorporating some kind of roller cage to keep everything positioned properly. Which often increases complexity and adds more small parts into an already small part.

Attempting to solve the problem

One of my first attempts as solving the problem was to design a bearing that was printed in several pieces and needed to be assembled. That way the rollers could be a snug fit inside the bearing with zero clearance. This encouraged the rollers to actually spin properly and not just slide. I was eventually successful in creating a bearing that was both very smooth and very tight, there was basically no noticeable slop or wobble in the motion. But it came with big drawbacks as well. It needed to be assembled, requiring tweezers and a lot of patience. And it was difficult to get everything sized just perfect. A couple micrometers too big and it didn't spin, a couple micrometers too small and the rollers just slide and jammed inside the bearing.

Enter the “Planetary Bearing”!

I eventually had the idea to stop making traditional bearings. The design is basically a planetary gearset which is why I'm calling this a planetary bearing.

It solves most of the problems by:

- Rollers are more 3D printer friendly than balls - Geared parts force the rollers to always spin, no more sliding, ever. - Double helix teeth ensures.. - Smooth operation. - Everything is held in place. no roller cage required. - Clearances can be tiny (~30 μm ) The shape limits side to side motion and keeps the bearing tight. - It looks super cool! Makes a great fidget toy. - Design is simple and works well with the small size of bearings - Print-in-place: No assembly required. The only small downside is that it still requires small clearances to function. So it will never be as tight as a real bearing. But the only way to achieve zero clearance is to print separate parts and assemble. The convenience of print-in-place outweighs that downside in my opinion.

About this model

I have included 3 different levels of clearance. I find the “optimal” works best when printed from my printer but you may find it too tight or loose.

There will sometimes be a small break in period. The bearing may require an initial snap to get it turning but usually its almost nothing. It can help to spin it a few time to work out any imperfections and run smoothly.

Available Sizes

- 608: Most popular size. - 22mm Outside Diameter - 8mm Inside Diameter - 7mm Wide - 6001: Larger and stronger - 28mm Outside Diameter - 12mm Inside Diameter - 8mm Width - More sizes in progress!

Thank You!

I have worked hard to make this model the best it can be and I believe this is the best option for a 3D printed bearing. It should work well as a drop in replacement for actual bearings in your projects provided it doesn't experience heavy use or high speeds (It's just plastic after all)

I'd love to hear your feedback and see what projects you incorporate it into!