@rfxcasey

This is almost exactly how the original Logitech Trackman Marble worked, except that the three bearings were more like graphite balls locked in a plastic holder.

@chango

Bearings, graphite balls whatever, just something to keep the ball floating with minimal friction.

I don’t see a laser. Isn’t that just a normal optical mouse? I’m not setting out to be a negativist, but you guys at hackaday really don’t seem to be the technical type. Sorry.

This guy is definitely not the first one to think of this. I am not saying I am but I did think of it before him. This is an extremely poor prototype as well. And to the guy talking about the laser. I don’t think it will matter weather you use optical or laser but what you need to think about, and this ping pong ball guy didn’t is that the optical tracks based on differences in the viewed surface. Anything plain and white is not going to track nearly as well as using say a marbleized ball or something with some pattern on it. Also the sampling rate may be an issue as you typically don’t move a mouse as fast as you free spin a trackball especially for arcade games like centipede so you are going to want to get the fasted sampling mouse you can which may be a laser mouse but I good quality optical should work fine just saying. Higher resolution is going to be an improvement too.

@amingham

What if you used a secondary ball under the primary. The secondary would be tracked via laser and could have a pattern on it. The glass ball could sit on top of the secondary ball. With enough weight and friction when you moved the glass ball it would translate to the seconder. That way you could have a perfectly clear glass or crystal ball as the laser would not be looking at it but the translation ball underneath instead.

Woefully incomplete instructions. Yay, Instructables!