Black Heatsinks

Yeah, IIRC, anodizing is just a form of oxidation, if that's the right word to use. I had looked into a home anodizing kit some time ago. All it consisted of is some chemicals, a bunch of buckets, and electrodes to pass an electric current through one of the solutions. I do know that lye gets it off PDQ. LOL.

I'm sure that the use of a quality thermal compound would help a lot. I only mentioned it because I had problems with all of my monster heat sinks in that the motor was always a lot hotter than the sink after a run. It turned out that the sinks were only contacting about 1/4 of the surface area of the motor that they should have. I had to do some sanding before I got a good clean contact and good thermal conductivity. Now, my sinks heat up with the motors.

I'm just asking questions. All in all, I like anodizing. It acts as an electrical insulator and could save the day in some situations.

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

Originally Posted by AAngel

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

yup, it was.

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.

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!

[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.

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.

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?

Originally Posted by AAngel

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?

I'd use a layout dye normally used to dye metals for scribing marks on them.

Here's a link to an example (the dyes look pretty on metal)......

http://ami.thomasnet.com/viewitems/d...d-2?&forward=1

[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.

Originally Posted by AAngel

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.

I'd bet the heatsinks from Mike are type II (for color only). Type III is expensive and it to improve hardness and wear mostly. Ususally limited to chassis plates and such. As far as heat transfer, any anodizing will improve Al's heat transfer (both radiant and convective), by increasing it's emissivity and etching the surface which improves convection. Polished Al is the worst possible (except for conducting).

[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...