Drill Motor Mounts

[Josh Hambright]

When running our robot for about 45 minutes with little break in between (i know this isn't a good idea) we noticed the odd smell of melting plastic. Upon further inspection we realized that the drill motor mounts first had provided in the kits had begun to melt due to the heat generated by the drills...
has anyone else experienced anything like this? I remeber the drill motors from last year produced alot of heat but how do last years compare to this years?

we are planning on creating some heat sinks to put on the motors to help with this issue...
can anyone else relate?

[Dick Linn]

If your motors survive to the point where you get to competition, I would recommend that you treat them gently. Do not drive at low speeds and push things for long, as these motors use a lot of current near stall speed and the internal fans do not move much air, either. You only have a 2 minute+ match, so in practice, keep it about the same and check the temperature of your motors at similar intervals. If they get hot, back off or check for problems (friction, misalignment, wrong gearing...).

Last year, we never had a motor failure but we didn't go looking for trouble, either. We also had really low gearing which helped in pulling/pushing things.

[Josh Hambright]

we plan on keeping compressed gas of some sort like canned CO2 duster on hand to freeze the motors before matches just to be safe... we have done this in the past without any problems.

[Cory]

We hooked up one of those nifty large muffin fans. Whenever the motors have any current being applied to them, the fan will turn on. Im not sure how much good this will do, but its gotta be better than nothing.

Cory

[Justin Stiltner]

I would reccomend having that fan run continusouly, the reasoning behind this is that the heat that is generated by the motors doesent go away when the motors stop, in fact half of the heat is just penetrating the casing of the motor at that point, also if your close enough to the current limit of the 120a breaker that the fan will put you over.. you may want to change some things around.

just my $.02

[sanddrag]

Is there some kind of CAD drawing for those mounts so we can know all the dimensions and get them CNC-ed?

[WernerNYK]

WPI used a forced-air cooling system on the drill motors in 2001. It works extremely well; rarely do the motors even get warm.

[rbayer]

Originally posted by sanddrag
Is there some kind of CAD drawing for those mounts so we can know all the dimensions and get them CNC-ed?

Not sure about CAD drawings, but you can buy new ones from the MMH order form for $17 each.

[sanddrag]

Originally posted by rbayer
Not sure about CAD drawings, but you can buy new ones from the MMH order form for $17 each.

But we want aluminum ones

[Daniel Brim]

At the SCRRF regionals our motors overheated after 3 matches (we built heat syncs)

Muffin fans do work well, if run continuosly, we used them on our 2001 robot.

[Rickertsen2]

liquid cooling anyone?

[Al Skierkiewicz]

Originally posted by oneangrydwarf
When running our robot for about 45 minutes with little break in between (i know this isn't a good idea) we noticed the odd smell of melting plastic.

Sounds like you have a pretty good design. If the motors lasted for 45 minutes of near continuous duty without damage to motor or mount, I think you are doing very well. I would recommend in the future (to all teams actually) that you periodically check the motor temp. A handhled fan, a heatshrink gun on "cool", or some freeze spray ( I am not fond of this one, if wrongly applied, I believe it washes lubricant out of the end bearings and of course causes condensation to form on the cold metal) applied every 10 minutes during practice would be a good idea. We watch for heating during extended practice, at least I hope they are doing it this year.
To the other teams that are heating after just a few minutes, check you mech design and current draw on the motors. As has been discussed in these forums before, it essential to get the motors near to design speeds for the internal fans to work properly and place the motor in an efficient area of the power curve.

[jburstein]

the major problem with the "cool in a can" solution is that if applied to a hot motor, that stuff can actually cause your permanent magnets to crack (IE render your motors useless)...

On the other hand it does wonders (in my opinion) when properly applied to room temp motors before a match.

But for optimum results i'd say forced air combined with a heatsink is the way to go.

[Josh Hambright]

yah we were worried about the cracking of the motors if we cooled them so fast... so when we did notice the plastic getting hot after long periods of driving we would just stop, during driver tryouts we just put the robot outside in the fridgid indiana winter air for about 30 mins and that caused it to cool to the point it wasn't melting but it didn't freeze it instantly.

A word of caution to teams using compressed gases in cans: Read the labels, one can we were using contained ether and almost made us pass out when we sprayed it on the motors with other people in close proximity to the robot. Some of them could actualy be toxic if sprayed out in their liquid form and alot of them have warnings about skin contact and ingestion.... I have a scar on my arm to prove this stuff WILL cause frostbite, and yes it does hurt alot of if you spray it on yourself for anything longer then a few seconds.

[Al Skierkiewicz]

Did that can have flammability warnings on it? Ether is flammable!