Black Heatsinks

Originally Posted by AAngel

OK, I forgot about the sharpie trick.

I don't know about color helping with the heat dissipation, but I'm wondering if the relatively rough surface of the anodizing will inhibit the conduction of heat from the motor to the sink. As it is, there is already the hurdle of the anodizing on the motor can.

In any case, the black heatsink would look cool.

I was testing a griddle protoype at work (yes, the type of griddle for cooking pancakes) and the protoype was plain milled Aluminum. It was running about 650 F for the test. When I got the black teflon coated version later on, it was 550 F max under identical circumstances. The only difference was the black coating. It does make a difference. But at our temps, I'd probably guess about 5-8% improvement.:032: Still, better than nothing.

Yeah, but do you think the difference was because of the color?

I wish those heatsinks had a built in place to mount a fan. That would make them even more perfect.

I wouldn't call it a built in place to mount a fan, but adapting a fan isn't too hard.



I got the 12v fan from radio shack and run it off of the 4S pack. I use a small 12v regulator, also from radio shack, when I run more than 4S. I just drilled and tapped the heatsink for 3mm screws. There's more than enough meat there for the threads.

[BrianG]

AAngel: Dark colors have different heat emissivity ratings - which is why you have to set some of those temp meters for the material and color you are measuring. I had a link above somewhere which explains black body radiation; it's interesting reading.

Originally Posted by AAngel

I wouldn't call it a built in place to mount a fan, but adapting a fan isn't too hard.



I got the 12v fan from radio shack and run it off of the 4S pack. I use a small 12v regulator, also from radio shack, when I run more than 4S. I just drilled and tapped the heatsink for 3mm screws. There's more than enough meat there for the threads.

That looks like it would work great. I did not think of doing it that way. I like it!

Yeah, I'm a drilling and tapping fool. I got a set of Dubro drills and taps and they cover all of the sizes that you need for RC. If you don't want to get the whole set, the 3mm screws common to RC are 3mm by .5mm pitch. I used the standoffs that held my mechanical brake pads in place and four 3mm washers. These fans move some air.

BTW, I'm also a soldering fool. Almost all of these fans that I've seen come with this little bitty 28 gauge wire. I have some leads that I made using 20 gauge silicon jacketed wire with jst plugs. I remove the stock wires from the fans and replace them with my leads. Just being anal, but I have had a few of the stock wires break.

Originally Posted by AAngel

Yeah, but do you think the difference was because of the color?

yup, it was.

All of this regarding the color is interesting. At the risk of sounding like an idiot, I just have to ask. Does all of this mean that I can get my aluminum heatsinks to work better just by "coloring" them with a Sharpie?

[BrianG]

From what I understand, yes. Sort of. Anything short of anodizing adds an insulating layer on the heatsink. Sharpie ink is thin, but still a layer and not exactly "bonded" to the material. Anodizing is a very thin molecular bond.

I don't want to keep beating dead horse, but...from what I understand anodizing is a process by which aluminum is forced to oxidize, forming this layer of anodizing. If this is true, then black type II anodizing may actually promote the dissipation of heat, while type III may inhibit it.

I just know that type III is some pretty tough stuff. I had a tube that I turned out of 6061 aluminum, then knurled with some pretty aggressive knurling and then had type III anodized black. Although the anodizing did nothing for the tensile strength of the aluminum (it would dent if I slammed it again a brick), I was able to saw into a piece of wrought iron with the knurling without damaging the coating.

[nativepaul]

I am having some PC issiues at the moment and I don't think my order went through, I will be in contact with Mike tomorw to see if I can order another way. I will ask him what type it is and post his responce here.

[BrianG]

To verify your order, just create an account and view your order history. I believe as long as you use the same email address as what you used when you placed the order, it will link them. That is what I did and it worked...

[nativepaul]

Thanks Brian, I followed the link it shows order deleted, when I click details of the order it is empty except for the postage.
I think an overactive firewall is giving my PC some serious comunication issues.

[BrianG]

Sounds odd. I'm using the firewall included in my router as well as a software firewall on my PC (ZoneAlarm) and have no problems. Whatever you use for a browser, make sure it is a fairly current version, and maybe take a look at your security settings.