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Thread: suggest some large extruded aluminum heatsinks

  1. #1
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    Default suggest some large extruded aluminum heatsinks

    ebay, or website, doesn't matter. Location doesn't matter either (US, EU or Australia).
    Size should be 200 x 100 mm, a bit bigger is okay.
    Height no more than 50mm.
    Need 3 as I also want to swap the multipe heatsinks I had in my old projector.
    Last edited by Finale; 06-29-2017 at 08:52.

  2. #2
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    Adam Raugh had a site he recommended for heat sinks of all shapes and sizes, but I can't remember the name... Hopefully he will see this and reply though.

    Adam

  3. #3
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    http://www.heatsinkusa.com/

    Amy Mason over there has always taken good care of me. They have great prices for small quantities, for >50 piece quantities their machining prices are good too.

    If you don't already know, bear in mind any large extrusion is naturally going to have some bowing in the middle and a mediocre at best surface finish. If this is for use as an optical deck for a laser, it's best to get the working side faced off at a machine shop.

  4. #4
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    Nice selection and prices, thanks!

    It's not for an optical deck but it will be bolted at several points to a 10mm optical plate. Do you think bolting a 100mm x 200mm heatsink at 6 points to a thick aluminum with thermal paste in the middle will be fine?

  5. #5
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    Quote: "There is a theory which states that if ever, for any reason, anyone discovers what exactly the Universe is for and why it is here it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another that states that this has already happened.”... Douglas Adams 1952 - 2001

  6. #6
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    I think it depends on your thermal load and where you have it on the plate. Personally if the cross section was 100mm wide I wouldn't bother with getting it faced, but for 150 and above I would. The length dimension doesn't matter when it comes to extrusion cupping in this case. Even at 100mm I'd probably take a sander to it up to 800 grit just to get a better surface finish and therefore a better thermal coupling. All of that may not matter at all though if your thermal load isn't that big of a deal.

  7. #7
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    Here's an example of the bowing I'm talking about. Look at the gap between the ruler and the aluminum extrusions in the middle versus at the edge. At the edges of these two photos, there's no gap because the ruler is sitting on the extrusion, but in the middle there's notable bowing. The smaller piece here is ~90mm, with very little bowing. The larger piece is ~225mm and has a very noticeable bow.

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    This is caused by the nature of heat sink profiles like this, an extrusion that has far more material at one end of it than the other has different stressing, cooling rates, etc. as it gets extruded, so there's always going to be some natural deformation. That gap in these heatsinks can be negligible or as high as 3mm, depending on the extrusion size, alloy type, etc.

    Heat sink compound does a great job of removing air gaps, but it works much, much better in as thin a layer as is practically possible. If your extrusion has 1mm of bow along your 100mm cross section and is 200mm long, you're potentially losing a ton of efficiency and would actually be better off with a smaller heatsink with less bow.

    Facing the material is a quick and easy fix and should be pretty cheap at a machine shop.

    I hope that helps explain things for folks
    Last edited by araugh; 06-29-2017 at 13:32. Reason: My first image was crap

  8. #8
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    No, yeah, I get it. I feel like bolting from the middle and both edges every 5cm would bend it back but yeah a machine shop is an option for me as well.

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