This whole thing started because I stated in a post last season that my teams haven’t used CIMs for a few seasons and some people asked why.
I don’t expect everyone to run out and buy miniCIMs (please don’t as we will not have enough if that happens), but I wanted to share things I noticed and then tested.
Most of the discoveries were made during the dyno up/down test. As an aside, everything on motors.vex.com has a description of how we tested it. You do not need to assume how we tested, because we tell you in the “how we test” section.
We tested about 20 of each CIM and miniCIM. We tested CIMs you get from AndyMark and from VEX (they are the same motor from the same factory). They were all within 3-4% of each other. The stated motor manufacturer variance for these is 10%, but I have yet to see that much variance.
What we found is the CIMs ALWAYS heated up more than the miniCIMS during those tests. Now, we didn’t do anything with current limiting as we were just trying to quantify the motor specs as motor manufacturers do not do the up/down tests so their published performance data is a little higher than reality.
All of you need to make your own decisions on what to use and I’m not really interested in arguing with anyone on this subject. This is a complicated issue and I have found that testing with your specific configuration is always best.
Yes, I am sure our motors would have heated up more if we had more wheel scrub. However, I found it interesting that the motors didn’t heat up and our darn large breaker got so hot it would trip after about 2 or 3 hours of continuous practice. The motors (including the 775s) were happy.
I like distributing the heat across 6 motors. I just don’t like the weight hit of doing it with CIMs. 6 minis worked great for us (so did 4WD with all omnis) and we will likely use them again this year on our drive.
We have found that if you design your robot to win a pushing match you probably won’t be a high scoring robot (there are exceptions, but not many) in the latest styles of FRC games. What we have found to be more important is to make yourself “immovable” when trying to score. We did this by going to the rear peg when under heavy defense this last year. Depending on the game, 4 omnis may not make sense no matter what motors are driving them.
Why do I like 4 omnis? Simple. The T-bone! After 2011 Einstein when 973 made 217 their plaything by t-boning us I said, “never again”. If we used 4 omnis that year, then the 973 strategy would have been useless. Since we were protected when scoring omnis would have made perfect sense.
Anyway, I digress.