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Thread: Best heat-trasnfer housing for ld?

  1. #1
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    Default Best heat-trasnfer housing for ld?

    Hi all!!
    I'm a bit confused about best housing diode for best heat transfer to my baseplate (300x300x10mm thick+40mm high sink wings & 4xFAN air forced cooled)
    Just found 4 options (please see attached pic).
    Number 1 ordered to lasershowparts but not received yet.

    So, based on your experiences, which do you think that could be more efficient to transfer heat to baseplate?

    by design, I think maybe its number 1 cause it fits diode directly, so heat transfer is directly to base-plate.
    On the other hand, 2,3, & 4 hosts 12mm aixiz module so there are more metals involved and this could slow down heat transfer efficiency (although 3 is fan cooled).

    However, num 1 is a very LITTLE metal piece, so its contact surface to base-plate is smaller than the other 3...
    Please, could you share any thoughts?

    Many thanks!!

    Jordi
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  2. #2
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    In order of cooling capacity, I would say # 3 (z-bolt heatsink with fan) is the best, followed by # 2, then # 1, and finally # 4.

    What diode will you be running, and how hard will you be driving it?

    If you are running a low power single-mode diode and you don't plan to over-drive it, any of the 4 will be more than adequate.

    If you plan to run a 445 blue diode (they tend to run hot but are otherwise very robust), then option # 1 will be adequate.

    If you will be running a Mitsubishi 637 nm red (either the G71 or P73), I would suggest stepping up to option # 2, as it has a greater contact surface with the baseplate to move heat out, but so long as you don't over-drive it you could also use option # 1.

    For seriously over-driven diodes or the new 3 watt 9mm can 445 blues, I would go with the Z-bolt and fan (option # 3).

    Note that option # 1 works very well if you mount it to a small aluminum plate and then install a TEC between that plate and the baseplate. In that layout they work exceptionally well even for extremely over-driven diodes. But you have the added complexity of the TEC to deal with...

    Adam

  3. #3
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    All depend on how much power each laser is putting out. The more surface area the better for heat transference (better still with heat paste). Remember, No4 is not designed as a laser mount but as a rail mount for moving carriages (3d Printer head for example). I used them in my project but then my lasers are all running less than 200mW each.
    Cheers

    Colin.

    Anyone wanting to be a politician, should automatically be excluded from being one!

  4. #4
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    Thanks all for your thoughts!!
    The diodes are: Nichia 520 @1w 2x Oclaro 638 @700mw & NIchia 445 @2,5w. Time running: several hours!, this is for projector.
    so, Adam, based on this you think the same?
    many thanks!

  5. #5
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    Quote Originally Posted by buffo View Post
    (z-bolt heatsink with fan)
    TBH, I question how much use the fan will be on that as there isn't really a lot of surface area the fan is blowing onto.. Really dumb design!
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  6. #6
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    Ah! But is it blowing on or sucking off? (ooer missus)!!
    Cheers

    Colin.

    Anyone wanting to be a politician, should automatically be excluded from being one!

  7. #7
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    Agree that the fan is probably superfluous. But the Z-bolt units can really take a lot of heat.

    That being said though, I do still think that your brass mounts (option # 1 in OP's picture) coupled with a small TEC is the optimal solution. I had a pair of M140 diodes running at 2 amps each, and with a 40 mm x 40 mm TEC running at just 1.5 amps I was able to keep those mounts (and the diodes) below ambient temperature. If I cranked up the current on the TEC I could get them down near freezing! (But then there were condensation issues.)

    However, I also killed a pair of P73's by running them at around 700 mw in those mounts with nothing more than passive cooling to the baseplate. (oops!) Turns out the Mitsubishi's don't like to get hot... (Who would have thought, right?)

    Adam

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    Hi Dave!
    Yeah, design is awful and inefficient IMHO. It have 4 holes to forced air too come in. I think it would be more efficient blowing from behind!
    About blow or suck... there are lost of opinions here, specially on CPU PC modding. In general, seems more efficient blowing inside.
    Last edited by jors; 05-30-2014 at 05:25.

  9. #9
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    I'd really would go for the TEC option, but after reading LOTS of threads I'm very confused
    Know that temp sensor is required, along with TEC driver and so on...
    So, what I really would to know for instance, is simple a way to calculate how many WATTS TEC is necessary for each diode, and apply 12 or 8V...
    Anyway, by design/size, I prefer "1". Do you think I could "fry" any diode without TEC? the baseplate will be cooled from behind by 4 AC fans.
    thanks!!
    Last edited by jors; 05-30-2014 at 05:35.

  10. #10
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    Quote Originally Posted by jors View Post
    I'd really would go for the TEC option, but after reading LOTS of threads I'm very confused
    Know that temp sensor is required, along with TEC driver and so on...
    There are several different ways to run the TEC. One of the simplest methods is to purchase a thermostatic temperature switch and place it in series with the TEC. Something like this: http://www.mouser.com/ProductDetail/...ZuCSnDErY3g%3d It closes when it gets warm (which turns on the TEC) and opens when it cools off (which shuts the TEC off). Just stick it on top of the diode mount and you're golden.

    It's crude, but it's enough to keep the diodes from overheating.

    is there a simple a way to calculate how many WATTS TEC is necessary for each diode
    You can try to calculate it, or you can follow the example of what other people have used in the past, but really the easiest method is to just hook up the TEC and adjust it until it works. Most TECs will have more than enough capacity to keep up with the heat load, so the TEC will almost certainly be running well below it's maximum limit. Once you have it connected, you power up the diode at full current and let it warm up, and then you adjust the current through the TEC (by varying the supply voltage) until you get roughly the temperature that you want.

    Now, if you go with a TEC controller circuit, then it will modulate the TEC for you. This will give you very accurate temperature control (less than 1 degree difference in good installations) but you need that extra control circuit and a thermistor for accurate temperature sensing, which adds complexity and cost.

    Anyway, by design/size, I prefer "1". Do you think I could "fry" any diode without TEC? the baseplate will be cooled from behind by 4 AC fans.
    If you are running a Mitsubishi G71 at over 300 mw output or a P73 at over 500 mw output, then yes you can fry one using option # 1. I know, because I've done it. But if you keep the output power below those limits, you should be OK.

    Likewise, if you want to run an M140 blue diode at normal current in one of those mounts, you'll be fine, but I wouldn't try to over-drive it without a TEC. And I don't think I'd even consider running one of the 9 mm blues (the 3 watt units) in those brass mounts unless I had a TEC. (Those things get hot even at normal current.)

    Adam

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