This is FRC Team 3266’s first year at using mecanum wheels so we only purchased the wheels and not any of the mounting equipment because we didn’t know. Now we have everything else ready to order except the bearings. For mecanum wheels do we need to order 2 flanged bearings for each wheel just like the standard wheel? Also what size ID do the bearings need to be for the KOP axles (long bolts if that makes more sense)? One last thing, for the sprockets mounted on the CIMpleboxes should we just order 2 more double KOP sprockets or 4 single slightly larger ones. Thanks!
You’ll need 4 independent gearboxes for Mecanum wheels. The CIMpleboxes are pretty fast so you need a rather large sprocket reduction to go with them. This gets to be a bit of a complicated setup - with 4 CIMpleboxes and 4 sprockets, 4 chains to adjust, 4 Mecanum wheels to mount (not sure if you want live axle or dead axle.) If you read the various threads on Mecanum wheels, teams have had success direct mounting 6" Mecanum wheels to Toughbox Nano gearboxes (12.75:1 gives a pretty good speed.)
If we make the mecanum wheels direct drive is the sprockets with the key shafts the only thing we need to purchase (we have 2 more CIMpleboxes in the mail). And if we make them indirect drive do we have to purchase 2 bearings per wheel. Also exactly what size sprocket would give us the 12:1 gear ratio?
KOP Sprockets will give you 10.1:1, (56/12*26/12)(gear ratio * sprocket ratio) which would probably be ok for 6" mecanums. We used 12.5:1 last year with 8" mecanums directly driven, long shaft on the transmission.
For 12:1 you could swap the 26 tooth sprocket that came in the KOP with something larger.