Semistatic bearing

Introduction

This semistatic bearing is intended for use in trackball pointing devices such as those sold by Ploopy and efog.tech, as an alternative to static bearings and ball transfer units (BTUs). It has a main bearing sitting on subbearings (like a BTU), but the subbearings are embedded and don't spin (like a static bearing).

Github repository

I originally published this work on Printables, but have since moved it to Github to manage the project more effectively. You can still find some of my original models and basic instructions on this page.

For detailed project information and new semistatic variations, visit the Semistatic Bearing project.

Print settings

• All models are designed for 0.2mm layers.

• I recommend ironing (on all surfaces) for bearings with flat tops.

• No other special settings are required.

Supplies

Any ball bearings should work, but I recommend ceramic balls of at least G10 (preferably G5).

• You'll need four ball bearings for each semistatic bearing.

• My testing has mostly been done with uxcell 3mm Silicon Nitride G5 and uxcell 2.5mm Zirconium Oxide G5 ceramic ball bearings.

Bosch Rexroth 8mm BTU equivalents

This model uses 2.5mm, 3mm, or 3.5mm balls for the main bearing and subbearings. There are slots in the tops of the cases that can be gripped with a keyboard-switch puller for easy removal from a trackball.

1. Drop three balls into the three sockets in the bearing case.

2. Perch another ball on top of the claw.

3. Use the bottom of another bearing case to press the ball down and click it into place.

Spacers

If your bearings don't make proper contact with the trackball, use spacers to raise them in their sockets. You can download them from the Github repository.

Veichu 7.5mm BTU equivalents

I've made versions with open and closed tops, both with 2.5mm ball bearings. The subbearings are more secure in the closed-top version, but are harder to remove.

1. Press three 2.5mm balls into the three sockets in the bearing case.

2. Press the balls fully into their sockets with your fingernail or a hex key.

3. Perch a 2.5mm ball on top of the claw.

4. Press the ball down to click it into place.

Disassembly

• To remove the main bearing, push a small hex key (or something similar) through the 2mm hole in the bottom of the case.

• Point the claw into your hand (or a container) to catch the bearings when they pop out, or you may never see them again!