Internally finned box section heatsink

I wonder if anyone's search engine skills are better than mine, or even better someone who's seen this shape of extrusion before.

I've a little project due to start when some power LEDs arrive off ebay.

It will be an experimental moth attracting light, to a published design, but I'll need some long square heatsink to bolt the LEDs to.

The original used something with this cross section, I guess about 45mm square by about 150mm long.

I'm sure I could find some square tube and internally fit four long thin heatsinks off ebay, suitably milled to the above profile, but can anyone think of a source for a short length of the extruded section please?

Thanks

Bill

Generally these wind tunnel type heatsinks are designed to accept a fan on the end, yet not many fans come that small.

You seem to be suggesting you had something like this already, although I suspect it must be a minority sport and may be very difficult to replicate. I've certainly never come across anything this small.

Murray

You might find more available extrusions by searching for "hollow rectangular aluminum heatsink"

Had you thought about using pieces of aluminum structural framing material - the type that uses T nuts to join it? It is very cheap and readily available in several sizes. Depending on the size of the led's a pocket or set of pockets could be milled down to the rectangular core of the framing extrusion and the LED's mounted to the central rect. core. The angled arms and T nut holding rails would radiate the heat. Depending on how many you want to make, and how long they are, you may be able to get a few free offcuts of the framing if you can find a local industrial automation firm. These firms use miles of extruded framing and usually have offcuts around.

By the way 6063 aluminum is slightly better for heat transfer than 6061, if you can get it. Both are quite efficient at heat transfer, anyway.

You could save yourself a lot of effort though by using 4 lengths of ordinary finned heatsink extrusion (available many many places online and at electronic suppliers) glued or screwed to short plates or angles at the corners to form a tube shape like your picture.

Edited By Jeff Dayman on 03/08/2018 20:29:29

Cheers Murray, I've got some 40mm 12v fans in stock, and I've certainly got some 30mm plain box, but without any internal fins. 40mm box will give me more space to play with, and also fit the fans I have available.

I could go with a different sports-plan, and use 4 normal lengths of heatsink and just screw them together, but was wondering if anyone had seen this section available at a sensible price.

This heatsink on ebay is 120x100x18mm, so I could slice two pieces in half, and either use them to line plain box section, or screw them together to create my own box.

It's just that it would be easier to find a bit of the stuff ready made.

Cheers

Bill

p.s. Jeff Many Thanks, looks like we were typing at the same time.

Edited By peak4 on 03/08/2018 20:31:51

Hi Bill, here's a sketch of what I had in mind in my last paragraph.

**LINK**

Have a look at thes Fischer Electronik items.

Mike

Edited By Mike Poole on 03/08/2018 20:48:56

Bill,

It's not designed as heatsink, but ... This might be adaptable, and is widely available: **LINK**

https://docs-emea.rs-online.com/webdocs/0254/0900766b802540f1.pdf

MichaelG.

Google wind tunnel heatsink, at least two photos of what you seek in the first fifty results.

Neil