Driving omni-directional wheels

[VanZuiden]

Our team currently has AndyMark aluminum 8' omni wheels. Our plan consist of have a 4 wheel drive system, driving high friction wheels in back and the omnis in front. When preparing to mount the wheels we need to know a few things:

Where to find "hubs" for the wheel to place bearings in to.
also, since we plan to drive these wheels where can we find a 28 touth sprocket to drive. then as well how do we go about assembling all of this?

any help is appreciated,

thanks

[sanddrag]

Well, you can get a 1/2" ID 1.125 OD flanged bearing either from Small Parts (p/n BRF-08) or from AndyMark. I'm not too sold on the idea of putting that wheel on just one bearing though. Here's that might work. Make some standoffs, (round bar stock with hole in the middle) maybe about 1" long and put like 6 of them on the wheel (every other hole). You might be able to get by with nylon ones from the hardware store. Then, buy a sprocket big enough that you can put the same hole pattern in it. Also, bore out the center to 1.125" If you do not have access to machine tools, the hole pattern can be done with a drill press and a bit of careful planning and measuring but the 1.125 bore might need to be machined. Bolt the sprocket to the wheel with the standoffs in between. Put a bearing in the wheel. Put a bearing in the sprocket. Call it done.

Another thing you could do, if the bolt circle on the wheel is too big for the sprocket of your liking, would be to run a live axle. Make some 1/8" steel or titanium plates with something like a 1/2" hole and an 1/8" keyway. You can lasercut the whole thing, or you can cut the plate some other way and brach the keyway (or dremel if you are desperate). Bolt one plate to each side of the wheel. Use a 1/2" keyed axle and a 1/2" keyed sprocket.

If you have access to a machine shop, you can make some really nice aluminum hubs for the wheel.

So buy sprockets, www.mcmaster.com and www.sdp-si.com are good places to start your search.

EDIT: AndyMark sells a wheel hub 1/2" ID with 1/8" key for $16

[Alekat]

Sounds like you guys are off to a great start for a rookie team. I'm sure someobdy else who knows more about omni-wheels will post and help you out, but I just want to say don't be afraid to simply try stuff. That's what your first year is all about. Then again, a lot can be learned from the people on this site.

[bombadier337]

We just did this tonight so I know it works. TO save a little $$$, we bought one hub per wheel from AndyMark, and put it on backwards. That way, the drive shaft is supported in the middle of the wheel, as opposed to having a hub on either side. We threw on some sprockets, some collars, and threw them between two base mounted bearings and it works like a dream!

[falconmaster]

Originally Posted by VanZuiden

Our team currently has AndyMark aluminum 8' omni wheels. Our plan consist of have a 4 wheel drive system, driving high friction wheels in back and the omnis in front. When preparing to mount the wheels we need to know a few things:

Where to find "hubs" for the wheel to place bearings in to.
also, since we plan to drive these wheels where can we find a 28 touth sprocket to drive. then as well how do we go about assembling all of this?

any help is appreciated,

thanks

http://www.phxhs.k12.az.us/education...88&pagecat=139
this link to our website shows what we did