Bad MiniCIMs... failing to consistently start?

[Michael Corsetto]

Originally Posted by ThaddeusMaximus

These motors were ran with adapters that caused lots of noise, originally, so I'd imagine that's what really caused them to fail, since we were noticing similar behavior but never really bothered to investigate. I think swapping to the new hex adapters (which reduce noise to only the sound of air flowing) will vastly improve motor life, since they'll be taking less radial loads.

You appear to be assuming that, because of your improved set up, "less noise" means "less radial loads". This is not the case. In fact, load could be transmitted more effectively to the motor shaft in a tighter set up with less slop. It could be that your new set up is actually worse for the motors, even if you get better results (less noise, stronger shot, etc.)

-Mike

[JackFisher]

How tight was the press fit onto the motor shafts? If it was too tight, and you didn't support the other end of the motor properly while pressing them on, this would probably be the most likely reason the motors are damaged.

[SJaladi]

As Mike already mentioned, running shooter wheels directly off of the motor shaft is not the best option due to the radial loads the ball puts on the shaft (1923 did this in 2013 and 2014 and it was definitely not the best idea). However as it sounds that you are constrained by your design, a better solution than pressing the hex adapter onto the shaft, which may cause damage to the internals of the motor, is to use the 8mm to hex adapter which is available from both andymark and vexpro.

http://www.andymark.com/product-p/am-0588.htm
http://www.vexrobotics.com/vexpro/ha.../217-3255.html

Alternatively if you have access to a lathe and the correct broach you can make your own adapters very easily. (We made ours with a drill press but it was a last ditch effort as we didn't have access to a lathe, and the COTS ones were out of stock)