CIM Motors reusable?

nrogals · #1 10-12-2013, 19:59

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 · #2 10-12-2013, 20:01

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 · #3 10-12-2013, 20:05

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 · #4 10-12-2013, 20:06

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.

Patrick Flynn · #5 10-12-2013, 21:29

Quote:

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 · #6 10-12-2013, 21:40

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

Nathan Streeter · #7 10-12-2013, 21:48

Quote:

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...

Ether · #8 10-12-2013, 22:13

Quote:

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:

Quote:

Originally Posted by yash101

BAG motors have such a high RPM that they self-destruct their internal bearings.

Quote:

Originally Posted by stinglikeabee

I doubt speed was the root cause of the BAG motor failure. Improper side-loading on the bearing due to a shaft-mounted shooter wheel or an overtensioned belt was likely a root cause if the bearing itself failed.

yash101 · #9 10-12-2013, 22:16

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 · #10 10-12-2013, 22:20

Quote:

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.

yash101 · #11 10-12-2013, 22:24

Yeah. That is a good idea. I am not trying to bad-mouth them. As a matter-of-fact, I really think the CIMs are one of the best drivetrain motors!

Gregor · #12 10-12-2013, 22:39

Quote:

Originally Posted by yash101

Yeah. That is a good idea. I am not trying to bad-mouth them. As a matter-of-fact, I really think the CIMs are one of the best drivetrain motors!

Cool. That means you are the 99%.

z_beeblebrox · #13 10-12-2013, 22:45

Quote:

Originally Posted by Gregor

Cool. That means you are the 99%.

http://www.chiefdelphi.com/media/photos/19904

jeremy callahan · #14 11-12-2013, 09:57

we also had some issues with the bag motor. they ran great at the beginning but at the end of the day you would have to resort to "kick starting" the wheel to get it up to speed. If we could figure out how to stop having to "kick start" it we would like to use them. But we just don't want to have to rely on that in the middle of competition. That's our opinion on them.

Ether · #15 11-12-2013, 10:21

Quote:

Originally Posted by jeremy callahan

we also had some issues with the bag motor. they ran great at the beginning but at the end of the day you would have to resort to "kick starting" the wheel to get it up to speed. If we could figure out how to stop having to "kick start" it we would like to use them. But we just don't want to have to rely on that in the middle of competition. That's our opinion on them.

The information you provided would be much more helpful with further context. Please post details of your shooter design,including:

- how the motor was mounted to the frame and to the wheel

- disk compression

- gear reduction from motor to wheel

- speed of the motor at shooter operating speed

- wheel speed controller (e.g open or closed loop)

- duty cycle (continuous or on-demand)

- pictures would be helpful

- if you have it, motor amps at operating speed

But more importantly: Did you contact VEX, and discuss this with them, and send them the motor for failure analysis?

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