Four Little Motors

[Andy A.]

I suspect that at least one motor is turning the wrong way. However, we do know of at least one CIM motor this year that was clearly a manufacturing defect. It's possible there was more then one.

Removing each motor from the gearboxes and watching them spin in air would be a pretty reasonable way to check that they're all turning, and turning the correct direction.

[kevin.li.rit]

Originally Posted by Andy A.

I suspect that at least one motor is turning the wrong way. However, we do know of at least one CIM motor this year that was clearly a manufacturing defect. It's possible there was more then one.

Removing each motor from the gearboxes and watching them spin in air would be a pretty reasonable way to check that they're all turning, and turning the correct direction.

Would it be preferable to unplug all but one motor from the gearbox?

I would also check the speed controller or driverstation to see if the speed controllers are receiving all the same PWM signals for one gearbox.

[Andy A.]

Originally Posted by Coffeeism

Would it be preferable to unplug all but one motor from the gearbox?

I would also check the speed controller or driverstation to see if the speed controllers are receiving all the same PWM signals for one gearbox.

If I had no doubts about the CIM's this year, I'd say just disable one motor from each drive train by pulling the PWM cable and setting the controller to coast and attempt to drive. If the wheels turn the correct direction, test the other two motors the same way. If they don't turn correctly, swap motor leads or programmed commands to get things turning right, then test the other two.

The catch here is that I have a tiny sliver of doubt about the CIM motors now. The thread showing a 'seized' motor fresh out of the box details such an alarming QC issue that I still don't understand what went wrong. It's possible that other teams may have gotten a seized motor. Removing them all from the gearboxes gives you a chance to very quickly identify which motors are/aren't turning, and a chance to see if they turn by hand.

*Shrug* there are a couple ways to skin this cat. I like the 'take it apart and see each thing do a thing' approach right from the start.

[thmeans06]

Originally Posted by Andy A.

If I had no doubts about the CIM's this year, I'd say just disable one motor from each drive train by pulling the PWM cable and setting the controller to coast and attempt to drive. If the wheels turn the correct direction, test the other two motors the same way. If they don't turn correctly, swap motor leads or programmed commands to get things turning right, then test the other two.

The catch here is that I have a tiny sliver of doubt about the CIM motors now. The thread showing a 'seized' motor fresh out of the box details such an alarming QC issue that I still don't understand what went wrong. It's possible that other teams may have gotten a seized motor. Removing them all from the gearboxes gives you a chance to very quickly identify which motors are/aren't turning, and a chance to see if they turn by hand.

*Shrug* there are a couple ways to skin this cat. I like the 'take it apart and see each thing do a thing' approach right from the start.

I agree completely. We always test our motors before we ever mount them to a gear box. Then during assembly we test as we go as well. Having a simple process like that will help avoid mechanical issues... Then you get to make mean faces at your programmers when something doesn't work...