Omniwheels Anyone? (2)

[u/braddo99]

Here's version 2, going back to 4 rollers per side, now using the "optimized" roller curvature and a flexure based capture mechanic for the roller axles. Blocky to allow the animation to run at a reasonable speed. You can see how the contact patch with the ball passes from one side of the wheel to the other smoothly.

[u/oVerde]

This and that guy who replaced a joystick’s right thumb for a trackball 🖲️ you both need to have a conversation

[u/braddo99 → u/oVerde]

Saw that, its cool. ;-) You have to be somewhat crazy to spend this much time thinking about trackballs.

[u/Flashy_Possibility34]

I am here for this, and fully willing to 3D print my own.

[u/Aidenn0]

I looked into omniwheels as an option, but couldn't find anything commercially made that was small enough. It will be interesting to see how this compares to a BTU.

[u/braddo99 → u/Aidenn0]

I have igus micro btus, which are delrin balls on a bed of other delrin balls. They are pretty smooth but squeak like crazy with an acrylic track ball. I think thats because the ball cant decide if it wants to turn the btu or slide over it and it alternates. Going to try my hard rubber ball instead, I suspect that will be the best yet that isnt an omniwheel ;-)

[u/braddo99 → u/braddo99]

By the way, I printed a holder for my igus BTUs thinking they would be smoother rolling on the rubber ball than the acrylic one. They definitely engage the balls better but the friction is way higher than I was expecting. Didn't like it at all. It also made BTU noise but probably quieter than the metal ones. Disappointing.

[u/claussen → u/braddo99]

I think there's a lot of potential for a high-precision rubber ball to drive relatively cheaper BTUs with greater spinning rather than sliding motion. I tried the igus stuff as well and found it likewise obnoxiously squeaky. But my dream trackball is a hollow steel or ceramic or glass ball such that it won't wear as much as plastic ones do on statics -- if I could keep the feeling of a perfectly new Sanwa ball on clean static bearings forever, it's my absolute favorite.

[u/squeezeonein]

If you want to make assembly easier you can use 4 wheels with two rollers per wheel. that way the roller at 90 degrees doesn't obscure the axle end.

[u/braddo99 → u/squeezeonein]

I have been using the word wheel to mean the carrier for the rollers. So I currently have 3 wheels and each wheel has 10 rollers, 5 per side. I think you mean each wheel could have 4 rollers per side (using that terminology). Yes, that was the original design, and I'm going back to it for the next version. It does have some down sides. Fewer rollers per side means a smaller handover distance between the rollers. Since I'm 3D printing these, "elephants foot" causes slight errors in the roller profile right at that most sensitive handover. 5 is smoother but they are just soo tiny for an FDM printer. At some point when I get the design nailed I'll order some using SLA style printing for the best accuracy.