Heat Sinks for Drill motors

[JL Clifford]

I am trying to find heatsinks that will fit on the drill motors.

[Bah]

What we are doing is taking old pop cans cutting the ends off of them and folding them to make fins in them. Put a couple of them together to go all the way around.

[robolemur1236]

why would you need them?
we drove our bot into the ground last year and our motors barely hiccuped.
a heat sink is really a unnecessary and expensive addition if you buy them, making them can be too bulky

[Skabana159]

I gotta disagree with you, Lemur. Those drills can get pretty hot, just try "running them into the ground" and then doing the 5/10 second test. If you can touch the metal part of the motor for 10 seconds, you are A-OK. If you can touch it for 5 seconds, you should stop and let it cool. If you cannot touch it for 5 seconds, you are damaging the motor (we have melted a plastic casing before.)
I find a little muffin fan wire-tied on to be sufficient to diffuse heat from the drills.

[KenWittlief]

the drill motors have a pretty powerfull blower built into it - as long as you dont block it, it should cool itself ok

if the motor IS heating up to where you need a heatsink you need to lower your gear ratio

the windings are on the armature inside the motor -thats where all the current flows - the outside is only the magnets

if your motor is getting too hot, putting a heat sink on the magnet shell wont help the armature any, and thats where the wires are that will cook on you.

[Gabe Salas Jr.]

I do not exactly remember, but I believe that our team fabricated heat sinks for the drill motors last year (I should check with the rest of the build team, I was not there when they installed them). But I do remember that the drill motors got extreamely hot after two minutes. We made some minor adjustments to the set-up of our robot, and added the heat sinks, and it helped a lot. We can now drive it for about six minutes before we started to run a bit low on the batteries. No more burnination of the drill motors.

[sanddrag]

We used one of these on each motor with great success. You will need to hold them on with a zip tie as they are a slight bit small.

[JessR]

The major overheating and motor damage scenario is when you are running full current through the stalled motors in a shoving match. Then none of the power is converted to motion, it all turns into heat in the motor armature.
You can do the math - average specific heat of say 8 ounces of copper and steel motor parts, heated by 40 to 200Watts continuous power input. It heats quickly.
So a key is to train drivers to avoid shoving matches wherever possible, and keep them short when they do occur.
That said, anything which increases the rate of heat transfer from the motor body to the ouside air helps keep the average and peak motor temperatures down.
Its all about keeping up the highest 'delta T' between the motor surfaces and the air next to them, to maximize heat transfer rate into the air. Fans are great because they continuously displace the warm air next to the surfaces and replace with cooler ambient air. Heat sinks help because there's more surface area for heat to conduct into (aluminum is a much better conductor than air = higher heat transfer rate away from center of motor) and gives more surface area for air to contact = more air mass incontact to transfer heat into.
I love the coke can idea, it is elegant and simple.
Jesse.

[camtunkpa]

Just as a suggestion....we discarded the FIRST mounts last year and made our own aluminum mounts for the drills. We were one of the few teams without trouble stemming from the drills. Our aluminum motor mounts doubled as a heat sink and we never had an issue with the heating of out motors. Just my two cents on the subject.

Cliff
222 Alum.

[KenWittlief]

another solution - with the current sensors they gave us this year, you can setup the SW to monitor the amount of current being drawn, and backoff when the level reaches "FRY"