CIM Motor Burn Out Question

[Jeffrafa]

Direct driving from the CIM is fine for a shooter, in terms of gear ratio (You will likely see many teams with this setup). Depending on your wheel size, you may even prefer the mini-CIM (same diameter, 2/3's the length) because it has a slightly higher free speed RPM (6200 vs 5300).

However, as others have mentioned, be very aware of wheel balance and support for side loading - don't rely on the CIM motor bearings to support the side loading very long.

We actually siezed a CIM motor bearing during prototype testing after serious overheating that was left unchecked. We had plans all along to properly support both sides of the wheel with bearings, and use a coupler to the CIM, but we were getting by with a direct-drive hub for testing.

The pneumatic tire we had from Harbor Freight was seriously out of balance and had a severe wobble (not a problem for the hand truck use it was intended for). Despite our attempts to balance with washers, the vibration still shook our test stand and the loading on the motor limited our wheel speed to about 3400 RPM. After repeated testing, the screws holding the motor body together vibrated loose, and the rear motor bearing siezed. The motor was too hot to handle without gloves for at least 20 minutes afterwards.

With a properly balanced wheel this likely would not have happened, even with only the motor shaft supporting the wheel, but it is still a good design practice to try and integrate another bearing to take the side load if possible