Re: 4" Heavy Duty Mecanum Wheels
 

Just to be clear: given the same wheel radius and same motors and gearing, omnis have a theoretical advantage of 41% in speed, and disadvantage of 29% in force (compared to mecanum)

Re: 4" Heavy Duty Mecanum Wheels
 

For a dual pour, I agree that adherence between the outer "skin" and the inner "core" is critical, for the reason you stated.

However, adherence is not necessary between the core and the Teflon sleeve.

Re: 4" Heavy Duty Mecanum Wheels
 

So why not treat the outer rubber as an actual tread? Make the roller out of a hard material, and create the equivalent of a rubber slipcover that gets pulled over the roller core. Keeping the "tread" in place is a matter of appropriate engineering; I can think of several options.


Or you could form the roller core to have some overhang around small pits or slots, then pour the softer material around it. Even if it isn't adhering the same way a dual pour between highly compatible materials would, it is still mechanically secured.

Re: 4" Heavy Duty Mecanum Wheels
 

Absolutely there is a way to make a design like that work. In my experience on some molds I have done, even with features like that, the tread has come off (this is particularly true when dealing with skid steered drive wheels where they scrub along the surface, or even getting pushed sideways from an opponent). Again, I'm not saying its not possible, it is actually quite do-able. Just in my experience, I would do everything I could to make sure those two layers were bonded. Whether its a direct "insert mold", a spray on adhesive, a roughened surface, grooves or slots, or some combination of all of them...

-Brando

Re: 4" Heavy Duty Mecanum Wheels
 

Alright, thanks to everyone for your input. It looks like I've got some R&D to do. It might take me all summer, but I'll post some updates along the way.

Re: 4" Heavy Duty Mecanum Wheels
 

Late reply I know:

The core of our rollers were teflon tubing. I came up with buying push nuts what would grip into the teflon and pushing them on in opposing directions so that in order for the core to come out it would have to pull both push nuts off (also those push nuts had holes between all of the teeth biting into the teflon tube, resulting in even more of a mechanical bond.

I can tell you from the experience that it takes razors, a vise, vise-grips, and some sweat to take one of those rollers apart (we had a few duds and wanted to recover the teflon cores for re-dos).

Did you continue this project?

Re: 4" Heavy Duty Mecanum Wheels
 

The project lost steam, mostly because I got busy doing some other projects. After the 2012 FRC season finishes up I'm hoping to dedicate some time to it.