Dead cim

[Al Skierkiewicz]

Dale et al,
The CIM stall current is 133 amps but more importantly to our use the CIM is not ventilated. Prolonged high currents cause internal heating that damages the windings insulation and eventually leads to electrical failure of one or more windings. The bearings on a CIM are not designed for significant side loading and for many teams, this is an issue. If you are not using the CIM in a transmission for which it was designed, you need tor provide additional bearing support to the shaft end or friction will raise your load currents and eventual bearing damage will result. Remember that the CIM was designed for a special use in which the loads were intermittent and the speed relatively constant with no side loads on the bearing. Although CIMs have failed in our use, most were due to rough handling as described above. Long term heavy use, i.e. demo, can cause excessive heat. Keep an eye on motor heating and give the motors a chance to cool off before using again.

[Racer26]

1075 was experiencing some of our first CIM issues at the end of Waterloo regional this weekend.

I think this must have been a progressive failure, as they were still *working*, just not working *well*. We're using them in a 2+2 Swerve configuration, I'm unsure of the gearing, but its reasonable.

They were used all weekend at FLR, and then all weekend at WAT, plus whatever testing we did back in build. Everything seems free, so we dont think anything is binding. Its the first time we've seen the CIMs failing in 8 years of FRC.

[Grim Tuesday]

We burnt out all four CIMS in our 2010 robot during driver practice. One the alumni was acting the aggresor with another one of our robots, and, though I wasn't there, they somehow managed to start a small fire in the robot.

[joek]

we have been re-using our cims for 5 years now, and have not had a single one burn out. we have more of a problem with burning out controllers, as we have 3 or 4 bad victors. that said, we almost always have them run through a 12.75:1 gearbox. the only exception iknow of was 2009, where we used 2 cims to run a pair of stacked 6" 07'-08' KOP wheels; they were actually geared up slightly.

in any case, you want to be careful when working around motors or electronics, neither like metal shavings in them. we always tape off our RS and fisher-price motors when working around them, and vacuum out the area when done.