Thingiverse user emmett created a very clever single-print rotating bearing, a planetary gear.
- It prints in a single print
- It requires no support, so removing support (which is necessary for ball-bearing rings) which can be very difficult, is not necessary at all
- It is a series of gears with no axles
Each gear has a middle cut (if you’re thinking of 3D modeling) which is rotated around its center making each gear tooth a V shape. These fit into each other flawlessly, but also ensure that they cannot slide out of the ring. They stay put, and rotate very nicely.
Here is my print:
Using a large Allen wrench inserted into the hex hole in the middle, I gave it a good turn and it began moving. Now it rotates easily.
It inspired me to think of other ways to make bearing rings that require no support, but will not fall apart. Rather than use spheres, I decided to use cylinders, bevelled at the top and bottom to keep them within the rings, which contour to the cylinders. Each cylinder is close enough to its sibling that it should rotate freely, but they should not bunch up causing the bearing to fail.
Here’s the model:
The pyramids at the four compass points are my logo for 3D printing, a pyramid with two bits taken out to make it an “H”.
It’s a theory. I’m about to print one and see.
Update: Sadly, mine turned out like crap. The cylinders were too short and stubby, so they acted like spheres, toppling over in their tracks. There was too much open space between them, almost enough to fit a whole other one in the ring. That made it not rotate smoothly.
Oh well… back to the drawing board.