DIY heatsinks

[byteboy]

I agree with Duck-Twacy that the costs of the aluminium if bought new is almost equal to the price of new heatsinks.

So I think the only way to realy save on the costs of heatsinks would be if you can get the aluminium parts for free or at little costs, from the scrapheap of a metal workshop or something like that.

On the other hand, in this way you could create your own unique designed amplifier casing with verry cool (literally!? ) integrated heatsinks........................

[Magura]

Originally posted by Saibot
How about buying a sheet of Aluminium and then folding it ?

Folded fins heatsinks are supposed to be very good.
A thin (1-2 mm) sheet of Aluminium cant be that expensive). Folding it can't be that hard. When the folding is done glue it to a thicker copper/aluminium sheet.

/Tobias

I think you will find out that folding 2mm aluminium into something reasonably looking is VERY hard, and you will find that a 2*1meter sheet of aluminium will set you back something close to 100 usd....as somebody else mentioned...get the material of a scrap heap or buy real heatsinks.

Happy cooling

Magura

[Petter]

It would be MUCH easier to build a heatsink like this. I have seen a transverse variant as well.

Petter

[nuppe]

One source for thermal adhesive would be arctic silver:
arctic alumina thermal adhesive

It looks nice from the specs, neither electrically conductive or capacative. I haven't tried this myself, but i've used arctic silver II for my PC's heatsink and it works well.
It's not that hard to get either, but it wouldn't be cheap for a real large heatsink.

I have used some thermally conductive epoxy from Zalman that came with a graphics card heatsink, i think it would be ok, but i don't know if you could buy it separately or if it has low enough thermal resistance for this kind of application. The kind of heatsink you guys are talking about would have lots of joints, and that makes for lots of thermal glue in between the metal parts...

Has anyone thought of casting their own heatsinks?
This could be done on a low budget, but it's a lot of work.
I've been thinking about it, and even made a small prototype electrical melting oven, but my design didn't turn out to be that great (although i managed to partially melt a small piece of aluminium, there's a long way from that to a finished heatsink).

If anyone is interested, i got plenty of inspiration from Dan's workshop and his "improved Li'l Bertha", also try searching for "dave gingery" or "c.w. ammen" on google, these guys have plenty of books to dig into.

Even if you don't get as far as actually melting stuff, just heating the oven is quite the thrill, imagine having something you've built yourself glow orange-red from heat (as long as it's not your speakers, that'd be a bummer)! I wish i had some photos of my furnace when it was in action...
(Sorry for the threadjacking, couldn't resist spilling my mind a little)

/Andreas

[mwmkravchenko]

They can be done. I did it a long time ago and am fiddling with the idea now. The amount of work is huge. If you don't have casting experience the learning curve is steep. I took casting in school away back when. But I'm still thinking it over. It takes allot of preparation to get a good casting. Most websites advocate melting the aluminum in a steel crucible. That creates a very porous casting and not one good for a heat sink. The molds would be the hardest. Lost foam is a method that could work reasonable well. For the ultimate you could go with lost wax casting. The biggest hurdle is the foundry. And then the means of heating and the room to do it safely. The pluses are that you could cast as big a sink as you have the volume in metal. Ie. cubic capacity counts. A large crucible is important. They can be made as well. I think gingerly has a book on that to. The web site pictures tell you enough as to how to pull it off without the book if you think hard about what you want to do.


Mark

[willy]

IF there are recycling yards nearby, check them out. People throw away all kind of neat amuminum stuff. Your ideas will be as numerous as the pieces you find.

Finding good junk, is half of my DIY fun.

[Saibot]

Originally posted by Magura
snip
A different solution thats a little easier and just as good (if not better) is to cut sheets of metal and use metal blocks as spacers in between...then just bolt the whole thing together....now thats a 10 thumbs solution

Magura [/B]

Haven't thought on that one, sounds like an easy way to build it "cheap". But how thick should the sheet and block spacer be ?
And how big (area against sheet on both sides) need the spacer block be to optimally move heat between the sheets ?

Does someone have a formula ? I'm just to lazy to come up with one myself

/Tobias

[Magura]

You will find it hard to make a formula, it depends entirely what alloy of aluminium you are using, what type of compound you use in between the sheets and how much heat you need to get rid of.
Generally spoken you can say that you need about 1/3rd of the finn area on the spacer blocks and thickness of the finns is 1/20th of the lenght of the finns(from they leave the blocks).

Have fun

Magura

[Mark A. Gulbrandsen]

Petter said "It would be MUCH easier to build a heatsink like this. I have seen a transverse variant as well."

Hummm....The Patriot 100....Any relation to the Patriot Missle??

Mark

[zygibajt]

One of my first amplifiers I ever made (Aleph 4) used DIY heatsinks.
It took long hours to build them
Bartek