CIM Motors reusable?

[nrogals]

So we have about 11 older CIM motors. My team wants to know if it would be better to use our older motors for the time being until we get new motors later in the season, or if we should get the motors immediately. Is it really that bad to use older motors for a little bit? Would anything terrifyingly horrible happen to our prototypes? I believe that they are 2011 and 2012 motors.

[yash101]

I think you may have a tad lower performance, but CIMs and MiniCIMs shouldn't have the wear that evident. Just avoid reusing BAG motors. They don't have a very long lifespan because the bearings get destroyed by the high RPM, (14,000RPM). Those are the main motors that I have played with in the one year I have been of FIRST!

[magnets]

You might see a slight performance gain in newer CIMs, and the older ones may be slightly prone to failure, but you'll be fine. Our team routinely uses CIMs from at least 6 years ago and older.

[EricH]

If they're the same part number, go for it. I haven't seen any apparent drop off in performance from a CIM in storage.

[BobbyVanNess]

CIM motors are the most durable motors allowed in FRC. We've definitely gotten some mileage out of them, and I've never actually seen one go bad. Usually we'll use old CIM motors on our practice bot when we run out of new ones. I've never felt any noticeable difference in power on the drivetrain, where they're primarily used. This past year, a 2008 CIM motor actually wound up on the flywheel for our 2013 competition bot, and it worked absolutely fine all year. Though we made sure to peel the 2008 sticker off at our first regional in case any nosy pit scouts were to take notice

[Richard Wallace]

Originally Posted by bobby5150

CIM motors are the most durable motors allowed in FRC.
...

I will second that. CIMs are some to the most durable motors I have worked with in any application. However, like any motor, they can be damaged by overheating. See this thread for a good example.

Also see this other thread for some details on how CIM motors heat up when loaded to their maximum mechanical output power.

As many long time FRC participants can attest, CIM motors typically last several seasons unless severely abused. Measuring their free current is an easy way to detect such abuse. Typically that will be about 3 Ampere when first started and will reduce to about 2.5 Ampere after running for a few minutes -- friction reduces a bit when the bearings warm up.

[Whippet]

I'd say go for it. The only CIM I've seen die was stalled while hooked directly to a battery with a prototype that needed more torque than the ungeared CIM was willing to provide. Needless to say, there was quite a bit of magic smoke that day.

[jspatz1]

Unless you have some reason to believe they have been damaged by severe over-heating, there is no reason not to use them again. Their useful life is far greater than the mileage seen in most FRC seasons.

[Patrick Flynn]

Originally Posted by yash101

Just avoid reusing BAG motors. They don't have a very long lifespan because the bearings get destroyed by the high RPM, (14,000RPM).

Can anyone provide some evidence to this? I have never heard a report about BAG motor bearings failing. And would be interested to see what situations caused these issues?

[yash101]

Our shooter BAGs kept failing. We took a couple apart and the bearings were shattered, and looked partially burnt!

[Nathan Streeter]

Originally Posted by yash101

Our shooter BAGs kept failing. We took a couple apart and the bearings were shattered, and looked partially burnt!

... how'd you mount them? Did you direct-drive them and not support the shaft? If this is the case, I can't claim I'm surprised...

[Chris_Ely]

Originally Posted by yash101

Just avoid reusing BAG motors. They don't have a very long lifespan because the bearings get destroyed by the high RPM, (14,000RPM).

Originally Posted by yash101

Our shooter BAGs kept failing. We took a couple apart and the bearings were shattered, and looked partially burnt!

Please avoid making generalizations based on just your experience. Just because you had some motors fail does not mean that the entire line of motors is bad. There are many factors that could contribute to a motor failing such as how you use it. I highly doubt that the designers would use bearings that are rated under the RPM of the motor.

[Ether]

Originally Posted by Nathan Streeter

... how'd you mount them? Did you direct-drive them and not support the shaft? If this is the case, I can't claim I'm surprised...

The likely cause of the bearing failure was explained to him in an earlier thread but he seems to have ignored it:

[yash101]

No. I did read that post. I just haven't replied to it yet. We have a versa-planetary gearbox. I believe that those are built for motors like the BAG motors. It could be side-loading, but that wouldn't cause motor problems because doesn't the typical gearbox separate the motor from the drive-wheel?

[Ether]

Originally Posted by yash101

No. I did read that post. I just haven't replied to it yet.

Seriously? That was 2 and a half weeks ago... during which time you have made 200 posts.

As a general rule, if you haven't made the effort to discuss failures with the supplier to understand why the failures occurred -- especially in the case of products from major FRC supporters such as VEX -- please don't use this forum to bad-mouth their products.