CIM Motors reusable?
 

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.

Re: CIM Motors reusable?
 

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!

Re: CIM Motors reusable?
 

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.

Re: CIM Motors reusable?
 

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.

Re: CIM Motors reusable?
 

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 ;)

Re: CIM Motors reusable?
 

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.

Re: CIM Motors reusable?
 

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. :D

Re: CIM Motors reusable?
 

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.

Re: CIM Motors reusable?
 

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?

Re: CIM Motors reusable?
 

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

Re: CIM Motors reusable?
 

... 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...

Re: CIM Motors reusable?
 

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.

Re: CIM Motors reusable?
 

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

Re: CIM Motors reusable?
 

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?

Re: CIM Motors reusable?
 

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.

Re: CIM Motors reusable?
 

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!

Re: CIM Motors reusable?
 

Cool. That means you are the 99%.

Re: CIM Motors reusable?
 

Re: CIM Motors reusable?
 

That seems like it will go at 60MPH, carrying 500 pounds :D

Anyways, what was the free speed of this? Did the robot look like it was moving? I'd like to see that. Bring it to the PHX regionals 2014!

Re: CIM Motors reusable?
 

I strongly recommend following the links Richard provided. I've gained a deeper appreciation of motor performance from the graphs, explanations and descriptions by several posters.

Thank you all.

Re: CIM Motors reusable?
 

Let me get this straight, you want someone to bring a nearly 10 year old robot from South Carolina to the 2014 Phoenix regional?

Re: CIM Motors reusable?
 

Could you please provide more information about where these motors were used and what the loading set up on them was so that we can understand what went wrong here and be better able to understand at your failure?

Re: CIM Motors reusable?
 

Agreed. Richard's engineering analysis is one of those great resources that turns CD into a place where you can find quality, true, scientifically derived information. Thank you Richard!

Re: CIM Motors reusable?
 

Do you have any evidence to back up your arcing claim? Many brushed DC motors achieve speeds much greater that this, including FRC motors. See the 2013 Motor Performance Data sheet.
If you had you shooter wheels directly attached to the output of the gearbox, I could see the side loads from the discs being shot effecting the motor.

Re: CIM Motors reusable?
 

I brought that one up a couple weeks back, myself, when he thought that window motors had a lot of power and would be great in drivetrains...

...as a counter-example to show that while it could be done, it was NOT a good idea.



CIMs and their cousins (BIG CIMs from 2006 and 2007, Mini-CIMs, and Bag motors) are some of the most bulletproof motors in FRC, to say the least. I can't think of a single failure of one of those on any robot I've been involved with, even with some pretty hefty abuse. Drill motors, FPs, and BaneBots, I've heard of, particularly when someone abuses them a little bit (or in the event of motor manufacture defect), but very rarely do I even hear about a CIM failure.

Re: CIM Motors reusable?
 

I have a feeling that that may actually be the problem, though it seems unlikely. When a frisbee is being shot, it will put a force on the wheel, causing the motor to be sideloaded. That was partially our design, because the compression in the disks helps push them get accelerated better!

Anyways, I (and many others) are done with talking about THIS bag motor failure!

Re: CIM Motors reusable?
 

CIM motors do last a long time if they are not abused. However, the brushes do wear and produce varying resistance to case. Do not be surprised to measure a 2K to case. I have taken some apart and cleaned the dust around the brush assembly. While apart we also added some oil to the bearings.
Do not believe that simply mounting a motor to a gear box will eliminate loading problems. I have seen more than one motor damaged by improper mounting to a transmission. Also, depending on design, a severe side load on a transmission can translate to the motor shaft.
The good news, a CIM smells really bad when it has been abused. Take a good whiff at each end of the motor. If it smells burnt, don' trust it. A CIM motor that has been abused and shorted some windings will have less power output and lower free speed. There are several other failures that occur if you follow the links above.

Re: CIM Motors reusable?
 

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.

Re: CIM Motors reusable?
 

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?

Re: CIM Motors reusable?
 

Could you provide some more info here?

When you say ran worse at the end of the day was this a competition day with ~2 minute matches being run or a testing day where the motors were run much more continuously?

In either above situation was a motor cool down period allowed?

After experiencing these required "kick start" were the motors replaced or did the issue not appear at the start of a 'new' day?

What was the use of these motors and the expected loading?

Re: CIM Motors reusable?
 

The some of the bag motors had a manufacturing issue with the brush assembly. It was documented with the fix on team update 2013-04-09.

Re: CIM Motors reusable?
 

Hi jeremy callahan,
There was a documented manufacturing defect which affected some BAG motors. We at VEX/IFI worked very closely with FRC teams, our motor manufacturer, and FIRST to identify the problem and provide a retrofit to teams.

http://content.vexrobotics.com/vexpr...s_20130411.pdf

In addition, we've ensured that this problem will not happen moving forward. 100% of BAG motors in our warehouse have been retrofitted, and ALL of them were dyno tested in-house to ensure performance within 10% of our published spec. (It turns out, all of them were within 5%.)

If any team experiences a problem with a BAG motor, I hope they will immediately contact our customer support team by emailing prosupport@vex.com or calling 903.453.0802 We pride ourselves on our customer support, and want to "make things right" if you have an issue.

-John

Re: CIM Motors reusable?
 

yash101,
I'm sorry to hear your team had BAG motors fail. Did you contact our customer support group?

If any team experiences a problem with a BAG motor, I hope they will immediately contact our customer support team by emailing prosupport@vex.com or calling 903.453.0802 We pride ourselves on our customer support, and want to "make things right" if you have an issue.

Based on some of the other comments in this thread, it sounds like it might have had something to do with your application, but of course we'd be happy to talk it through with you and your team.

If you suspect there is some problem with the BAG motor in general, we want to help resolve it, or identify what is really going on.

Take Care,
John

Re: CIM Motors reusable?
 

Thanks. I'll talk to my team about it. Right now, it isn't too big of a deal anymore. All our other vex products perform the way they should!