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Unread 29-01-2014, 21:11
Lil' Lavery Lil' Lavery is offline
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Re: Connecting 4in omni wheels to a cimbox

Quote:
Originally Posted by Topperbotics View Post
We are also concerned that the wheel will not extend beneath the gearbox. Do you have any tips on this?
To address you concern, a 4" diameter wheel will just barely extend beyond the top and bottom of a CIMple box if mounted directly to the output shaft. In all likelyhood, any mounting hardware you use will end up extending beyond the edge of the wheel, and even the compliance of the carpet may cause issues with the razor thin margin for error.

My tip is simple, don't mount the wheel directly to the output shaft of the CIMple box. Use additional gears, chains, or belts from the output shaft of the CIMple box to power the wheel on another shaft. This serves two purposes:
A) You no longer have to worry about the dimensions of the gearbox and the wheel
B) You can add additional reduction

Point B is particularly important. Assuming you're using a CIM (or MiniCIM) as the drive motor, a 4.67:1 reduction is not enough for FRC drive applications (assuming you're anywhere near the weight limit). With such a small reduction, the load on the motor will be quite high. As a result, the motor will spin at a lower RPM and draw significant current. This will put a strain on your battery and quite possibly cause you to trip the 40A breaker for that motor if you run the motor for a prolonged period.

I'd suggest reading some of the terrific resources out there on designing a drive system for FRC applications.
http://www.chiefdelphi.com/media/papers/2429
http://www.chiefdelphi.com/media/papers/1378
http://www.chiefdelphi.com/media/papers/2597
http://www.chiefdelphi.com/media/papers/2755
http://www.chiefdelphi.com/media/papers/2274
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