where to buy large heatsinks...

[snarfer]

I'm prototyping a couple of designs and looks like I need some pretty hefty heatsinks made. One design is 12 inches square, the other is a 9 inch diameter circle. They could be aluminum with copper heatspreader. I've tried a few companies I found on web, but they aren't set up to produce this size. Any suggestions?

[TigerhawkT3]

Perhaps a surplus heatsink.

[Ken_McE]

I buy used ones off eBay. You need to check that it has an area with no pre existing holes where you can mount your parts.

[Skywise]

Try your local aviation maintenance companies (usually around a major airport). I've been able to get a few nice pieces of aluminum from them that work great as heat sinks.

-Sky

[Lightingguy321]

Aavid Thermal alloy makes some fairly large custom heatsinks and some of their larger CPU heatsinks may be appropriate for your application.

[mds82]

depending on the size, you could always just use a larger sized CPU heatsink.

[FrontRanger]

I'm prototyping a couple of designs and looks like I need some pretty hefty heatsinks made. One design is 12 inches square, the other is a 9 inch diameter circle. They could be aluminum with copper heatspreader. I've tried a few companies I found on web, but they aren't set up to produce this size. Any suggestions?

You've probably already thought of this, but just in case... if your design does not rely upon the heat sink for mechanical support, you can use multiple smaller heat sinks. That is, it might be cheaper and easier to find four 6"x6" pieces than one 12"x12" piece.

[snarfer]

Thanks for the suggestions everyone. I'm sure I will be trying a mixture of all these approaches for my prototypes.

I do also wonder if anyone has had any experience with having a custom heatsink made, and what their experience was regarding that.

[TigerhawkT3]

Yes, I have tried that.

http://www.candlepowerforums.com/vb/...d.php?t=187912
http://www.candlepowerforums.com/vb/...d.php?t=187019

I'd recommend buying a pre-made heatsink.

[jtr1962]

When I did my LED taxilight project a few years ago we did a small run (110 pieces) of a custom heat sink. Usually unless you're making thousands there is no cost advantage doing so. The tooling costs kill you (I think we paid $10,000). We had hoped to get an order for thousands but were undercut by competitors offering a cheap but inferior design.

Ebay is good for heat sinks. Here are a few of the more interesting ones:

http://cgi.ebay.com/ws/eBayISAPI.dll...MEWA:IT&ih=022

http://cgi.ebay.com/ws/eBayISAPI.dll...MEWA:IT&ih=022

http://cgi.ebay.com/ws/eBayISAPI.dll...MEWA:IT&ih=022

If I had $350 laying around the 12.75"x13" copper one looks very interesting. I could probably keep the hot side of my thermoelectric modules with a few degrees of room temperature.

[Gomer]

http://www.alphanovatech.com/

Pretty sure they do custom work. They also have a bunch of stock large (not as big as you indicated) efficient heatsinks