High-Low gearbox?

[ksafin]

Actually we are indeed testing with CIM's.
We want to gear them for speed to prototype a launching mechanism.

[Aren Siekmeier]

Originally Posted by ksafin

Actually we are indeed testing with CIM's.
We want to gear them for speed to prototype a launching mechanism.

If you want something like 2:1, I would go with the sprocket and chain suggestion, although you may not have sprocket with a 5/16" / 8mm bore lying around. We used a 10:42 chain reduction with #25 chain of off CIMs (and then CIMple boxes and RS775s) in our tests with 8" wheels, and the speeds were plenty for any half court shot or closer. With 4" wheels you would want something like 16:32 (all these sprocket sizes are available from Andymark, although it's better not to wait for things to ship unless they're going on the final product) to get comparable speeds. Alternatively, you could find some timing belt pulleys in that range and find some quick and dirty way to fasten the large wheel to the shooter wheel, or whatever it is you're turning. I realize you may not be testing a shooter wheel, but for most of these mechanisms the speeds required are in the same ballpark. You shouldn't need to gear the CIM up. If you absolutely must, try swapping sprockets/pulleys as already mentioned.