Modifying CIMs to implode?

[Justin Stiltner]

Going from questions similar to this in the past... it would seem to be legal... because it specifies that you cannot modify the internal electronics of the motor, but you can modify the housing... hrmm... maby this is one of those times where they give you enough rope to hang yourself.... because as the steel was removed it would also mess with the magnetic flux inside the motor and probably lower efficiency, similar to removing the metal band on the FP motors.

[Cory]

It might be legal with how the rules are currently stated, but Jeff's example of 2003 and 68 also read that their robot would be legal (or in a grey area, at the very least) until FIRST specifically outlawed it.

I think this would be a similar case, given that it would be a safety hazard and just plain dumb

[Karthik1]

Q 1330: Under the restrictions specified in <R31>, is it permissible to turn down the housing/case of the CIM motors to reduce weight?

What if they want to change the material of the housing rather than make holes in it and destroy it's structural integrity, although neither are worth the trouble. If you want to loose weight I am sure there are plenty of other places where you can loose it.

[Andy A.]

This has been done. I remember very cleary seeing shiny CIM motors on 190's bot last year. I asked a friend of mine who was on the team why the CIM motors looked so skinny. He pointed out that <R31> allowed for modification of the motors structurally, not electrically. I agreed that it was legal, but wasn't sure if it was worth it. I forgot how much weight they lost with this. Obviously, they competed with them, so if anyone questioned the legality of the modified motors, it didn't go anywhere.

My guess is that FIRST will allow it, again. Of course, my preference would be to just not use all 4 of those heavy guys, but alas..

I don't like heavy stuff.

-Andy A.

[Arefin Bari]

I have to go with what Dave and Cory said. Its hazardous.

-Arefin.

[Al Skierkiewicz]

My guess is the answer will be NO modification of motors is allowed. I do not think that they can save enough weight to make it practical to turn down the case, the majority of the weight is in the armature, shaft and magnet assy anyway. My guess is the case is about as thin as it could be now, the company is afterall, trying to make a profit and have already made the determination as to the minimum material the case needs. If the answer comes back that the case can be modified, I can tell you we will experiment with case mods just to be sure that there is no real advantage.

[jgannon]

Originally Posted by Al Skierkiewicz

My guess is the answer will be NO modification of motors is allowed. I do not think that they can save enough weight to make it practical to turn down the case, the majority of the weight is in the armature, shaft and magnet assy anyway. My guess is the case is about as thin as it could be now, the company is afterall, trying to make a profit and have already made the determination as to the minimum material the case needs. If the answer comes back that the case can be modified, I can tell you we will experiment with case mods just to be sure that there is no real advantage.

While you're right that the weight savings aren't significant, R31 seems to clearly state that modification of the housing is okay, as ahecht pointed out above. Do you have a counterpoint from the rules that would indicate why a team couldn't do this if they really, really wanted to?

[tkwetzel]

Originally Posted by sanddrag

Teams have done it a small amount before to remove the black paint and have a shiny finish.

You could probably remove the paint easier with sand paper, if that was your goal.

[ahecht]

Originally Posted by tkwetzel

You could probably remove the paint easier with sand paper, if that was your goal.

Yes, but it wouldn't have that hot-off-the-lathe shiny look then.

[Greg Perkins]

The CIMs have a waterproof outer coat (black) by removing the coating it allows the motor to cool without the insulation of the hard rubber coating. Tyler Forbes on 190 was on my team for a number of years back in high school, and did battlebots for a number of years....a lot of people who used them turned them to save that fraction of weight, and allow for cooling....

Apparently since 190 did it...FIRST probably never had an issue...its that grey area we need to worry about...

[ConKbot of Doom]

Hmm well I'll be waiting to see the reply to this question. I have been wondering about strapping some aluminum oil filter heatsinks onto the CIM motors for cooling. And turning it down or sanding off the paint would certainly help with thermal conductivity.

http://www.jcwhitney.com/autoparts/P.../p-298/c-10101

Between those and a 120mm fan by each transmission, that should help keep the CIMs cool

[Cory]

Originally Posted by ConKbot of Doom

Hmm well I'll be waiting to see the reply to this question. On I have been wondering about strapping some aluminum oil filter heatsinks onto the CIM motors for cooling. And turning it down or sanding off the pain would certainly help with thermal conductivity.

http://www.jcwhitney.com/autoparts/P.../p-298/c-10101

Between those and a 120mm fan by each transmission, that should help keep the CIMs cool

That's a good idea, and better than nothing, but that mainly cools only the casing. The internals are still pretty hot, and by the time the casing is hot, they're VERY hot.

Still, like I said, any cooling is better than none

[Bruce C.]

I'll defer to any thermal analysis guys, but doesn't a black body radiate heat more efficiently than a shiny aluminum surface?

[M. Hicken]

they might as well try machining 1/32" off all of the pwm prongs on the controller, and while at it, lets shave off the insulation on the wires, thats got to be half a gram right there

[dez250]

Originally Posted by Andy A.

This has been done. I remember very cleary seeing shiny CIM motors on 190's bot last year. I asked a friend of mine who was on the team why the CIM motors looked so skinny. He pointed out that <R31> allowed for modification of the motors structurally, not electrically. I agreed that it was legal, but wasn't sure if it was worth it. I forgot how much weight they lost with this. Obviously, they competed with them, so if anyone questioned the legality of the modified motors, it didn't go anywhere.

My guess is that FIRST will allow it, again. Of course, my preference would be to just not use all 4 of those heavy guys, but alas..

I don't like heavy stuff.

-Andy A.

Maybe the reason why FIRST "allowed" it is because they did not know about it. If you look at one of the rules [the number escapes me now] you can not modify the integrity of a motor. This means you cant modify it physically or electrically. You can remove the gearbox on the fisher price motor and globe motor or alter them as they are not considered integral this year. But if you try to "skin" a CIM motor i would suggest you to have extras as many inspectors this year should have you to replace it.