High-Low gearbox?

[R.C.]

Originally Posted by ksafin

Well essentially we'd just like a gearbox where we can choose the gear ratio.

Does modulox accomplish that?

And if so is there anything cheaper?

I guess the better question would be:

-What are you attempting to do?

-Are you prototyping?

-RC

[lemiant]

If it's a muti-stage gearbox you could straight up switch the big and small years, thus inverting that part of the reduction.

[billbo911]

If you have the room and weight allowance to spare, chain and sprockets would work well for this. Attach a larger sprocket to the motor and a smaller sprocket to the driven axis. Just make sure the motor can handle the torque increase applied to it.

[ksafin]

We're trying to gear a motor for speed, but would like the ability to gear it for torque if we see fit with the same item purchased

[billbo911]

Originally Posted by ksafin

We're trying to gear a motor for speed, but would like the ability to gear it for torque if we see fit with the same item purchased

If you take the example I used, just swap the sprockets.

[ksafin]

That still doesn't have as much as an effect as a motor geared for speed though.
The motor would still be geared to be slower, which really isn't what we want.

Yes, what you said will make it faster; but not to the degree we want to reach.

[Aren Siekmeier]

What speeds are we talking about? All of the kit motors that don't already have a gearbox on them have a free speed of 10,000+ rpm (with the exception of the CIM at ~5000). Are you sure you need more than 5000 rpm? And I'm assuming this is not your drive and you're using 4 CIMs in your drive, so in that case, more than 10000rpm?

[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.