video : https://www.youtube.com/watch?v=N2V0BuoXlf4
These bearings are espacially designed for 3D-printing. These bearings don't use regular balls like other bearings but it uses specially designed for 3D-printing balls. This insures the most supple 3D-printable bearings with the least amount of play. The bearing prints in only one piece, fully assembled. You may have to wreck the balls a little lose after it has printed because the tolerances are very small. For the best result you can lubricate it with some grease. Hope you like it and can use it in your project. (results can depend on printer settings and type of 3D printer used).
I added a new 3D model of the small bearing to the file section called "homemade_printable_bearing_heavy_small_V3_easy_printable.stl" . With this model there is more space between the inner ring, the balls and the outer ring. This model should print more easy then the previous model but there will be more play between the inner and outer ring. This model is made for people who have trouble printing the first version. I'm sorry for this but I made the first version so my printer could print it without any problems. I didn't anticipate for the use of other printers. Hope this new model will be printable on most other 3D-printers.
small bearing (V2 and V3): inner diameter = 12 mm
outer diameter = 40 mm
height = 12 mm
big bearing: inner diameter = 53 mm
outer diameter = 81 mm
height = 12 mm
Have a nice day!