mounting luxeon K2 heatsink

[bonj]

Hi,
I am trying to make a bike light out of luxeon K2s and essentially what I have currently got is this:

and I am just pondering as to what the best way of mounting this LED-and-heatsink combo into a tube would be... and thus what sort of tube to use. Has anyone done this with this particular heatsink or got any ideas on how I could do it?

 

[hank]

Only the thought that you may want an air scoop, so motion of the bike will pull air across the heat fins.

 

[bonj]

thanks hank,
unless an air scoop will definitely be imperative, I think i'm going to try and keep it as simple as possible.
The thing that I'm having trouble envisaging is the actual method of attachment of the heatsink / LED board combo into the tube. Do you know of some sort of putty i can use?

 

[hank]

Nope, been wondering, but remember those finned heatsinks are designed to transfer heat to air. They're not a big thermal mass, they're a little mass with a lot of surface area.

Most flashlights use a big flat metal disk that transfers heat directly to the mass of the body/head metal of the flashlight.

I know they use the same stuff CPU heatsinks do, thermal paste or glue loaded with metal to transfer heat (and use it as thin as possible, it's just to fill gaps, it's better than air but much worse than metal as a heat transfer medium).

 

[hank]

Hey, heat pipe with cooling fins:

http://www.circuitcity.com/ssm/Ther...91058/catOid/-12973/rpem/ccd/productDetail.do

 

[scott.cr]

Is the heatsink basically cylindrical in shape? It could probably be bonded into an aluminum tube with thermal transfer adhesive (Arctic products are pretty much the only game in town here).

My opinion: The heatsink fins are not necessarily to transfer heat to air. They are to "wick" heat from the emitters more quickly than a solid metal mass. Aluminum does not conduct heat as quickly as other metals (such as copper), so the fins are added to speed things up.

Since it's a bike light and you have the advantage of a moving air stream, you may consider not bonding the heatsink all the way into tube so that the valley of the "V" formed by the fins is sticking out of the tube. If you leave the back of the tube open, air will be able to flow through axially.

 

[yellow]

Bike - Light ?

hopefully this piece (of much and unnecessary work creating junk)
was a present, or You had it already for that one year when it was medium notch (and payed this ridiculus amount then)

anyone else who reads this tread:
get something like this: http://www.dealextreme.com/details.dx/sku.5971
You are cheaper, protected against the elements, ..., with almost no additional work (individual back cover plate with switch and connections, thats all)