Cylinders Bearing, 42x12 mm, demountable.

Made with Spaceclaim education license.
Considering the difficulty of printing spheres, especially small ones, I decided to go with cylinders. The problem is, it adds contact surfaces so it reduces performances. So I tried to reduce them as much as I could by using a thin track on the rings and carved the sides of the cylinders to avoid too much frictions between them. In the end, there are just two rings on each cylinders that will be in contact with other parts.
I also converted manually the 3D model to add facets where It's needed to make them as round as possible.
The performance of this thing will depend on the precision of your printer and the size you decide to go with. I believe that the bigger it gets, the better it will run since the 3D STL file will be printed with more fidelity.

Print instructions

Best XY resolution: 0,1 mm
You will need to use support for the two parts of the outside ring.

Assembly steps:
0 - make sure everything can fit together. Remove any support/ printing imperfections.
1 - Snap the two parts of the inside ring together. They can't be separated again without big precautions.
2 - Place one outside ring part around the inside ring
3 - Place all the cylinders in the circular track
4 - Place the last outside ring part and turn to lock
5 - It should work!

I made this bearing for personal use. It had to meet two needs:

Being easy to assemble and print since it's one of my first prints and I own a low cost printer (alphawise U30)
Being fully functionnal and able to handle some axial force for it's size, weight and material.

The rounded parts of the design are just here to reduce the number of break points, altrhough it adds to the aesthetical side of the Thing.

I stay avaliable to answer any question.
You can use this design for anything but commercial use.