Heatsinks for DIY LED lamps

Keesje said:

But then the surface that Cree mentions, has to be bigger then that of SupraDSL.
Or not?

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Keesje said:

ok... Don't get it, but I will study a bit more on it.

Edit: I just read your explanation in #1782.
I (think) I get it now.

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Greengenes707 said:

Wish you would understand what you are looking at. The 140mm are 75w sinks. Actually handle 100w dissipation well under Crees specs.

HSusa give options right....one size/price doesn't fit all correct???(rhetorical)
Same goes for pin sinks. Different sizes and price for different applications.

4 140mm sinks can more than handle the 250w your using. And can actually fit 3 cobs fine if you started with a blank and want to get technical. That is the point, better cooling with less weight and cost. Using ones like 100mm for 25w application would be cheaper and more efficient at cooling than any extruded profile...physics and thermodynamics.

I suggest checking yourself before you wreck yourself. Get the facts and data straight first.

Angled aluminum has been in DIY since my drone and will remain for applications like pins and cpu coolers.

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dom-one dela nooch said:

yes fully aware that the pin heatsinks run at lower temps but was no aware you could put 3 on an heatsink so thank you for that info but whats with the checking yourself line as bit passive agessive for no reason !

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nogod_ said:

Hello all, its heatsink appreciation month here at RIU and in the spirit of the holidays I have been crunching numbers for my latest project: attempting to incorporate round-pin heatsinks into a forced-air duct, or "cool-tube", or "vinyl fencepost" as it were.

Unfortunately the best tool for the job turns out to be elliptical fin heatsinks. These work best because they are designed with the direction of the airflow in mind. In this configuration all of the fins are arranged in a uniform direction which allows for low resistance and maximum airflow in this type of application. They look like this and I cant find any for the price I want. oh well:

Next best are round-pin sinks. I found this fun little calculator to play with....http://www.myheatsinks.com/calculate/round-pin-heat-sink-calculator/

It only calculates for square sinks but in my case thats actually preferable.

So plugging my numbers in.....100mm x 100mm x 40mm with 60mm of clearance in the tube [4" x 4" x 36" tube]. i get about .34C°/w with an airflow of 324lfm from my fan. i realize thats just the first heatsink in the line and the latter sinks will inherit a higher Ta
But at least it gives me (maybe you) a ballpark idea of what size sinks Ill need to get the job done.

Btw I converted from CFM to LFM using this calculator...
http://www.engineering.com/calculators/airflow.htm

Why is this significant?

Until now I had no idea how pin sinks work with active cooling. As far as I can tell, everyone is using them passively. Ive grown to like active cooling, maybe you like it to?

Maybe you avoid it because you like to run remote drivers like me and cable management gives you headaches.

Here's a secret:
4-pole m12 connectors.
They look like this and allow you to consolidate everything into one tidy package:

Thats the male side that i have hooked to the junction box on top of my bars. Kinda like an xlr but with as many wires[and poles] as you want and they are threaded so you dont accidentally unplug your shit.

Anyway, options!

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coreywebster said:

@SupraSPL or anyone with the figures already in their head.
What is the dissipation in W of those round pin heat sinks so many people are using, like the ones on cutter.au? I would work it out myself but I don't have one in front of me or the measurements of the pins and every other dimension. They say they can run a 3590 soft up to 50w but that doesn't tell me the actual dissipated Watts of the heat sink.
I have worked out the 70mm2 square ones I have but there must be a page where someone has worked it out already? I started reading but after the first 12 pages I thought I would just ask.
If anyone has that figure in their head it would be most appreciated.

Edit would the correct term be Watts dissipated or dissipated watts?

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fearnoevil said:

So I came up with this idea to do a water cooled heat sink for a 5 cob lite, but instead of 5 separate water blocks which are spendy and need too many connections (which = potential leaks), I decided to use a single 48" piece of 2" x 6" extruded rectangular aluminium tube instead. My idea (not as original as I thought after doing some googling it, someone's always stealing my ideas before I think of them, lol) is to cut and taper each end to remove the corners and then weld it up with a 1/2" fip fitting at each end.

If it works, I'm thinking of making 7 more to fill my grow space, connect them together with either pex or vinyl tubing, which will go to a heat exchanger consisting of a used car radiator and a box fan set up outside the grow room. So question is, has anybody seen or had any xp with a similar design, and does this sound like it will work? Not sure what kind of flow rate I'll need, so I'll probably get a variable speed circulating pump, but any advice or critique is appreciated ;?)

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Fastslappy said:

@ttystikk has already done this successfully
Don't listen to @Airwalker16 he gives bad advice

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fearnoevil said:

So I came up with this idea to do a water cooled heat sink for a 5 cob lite, but instead of 5 separate water blocks which are spendy and need too many connections (which = potential leaks), I decided to use a single 48" piece of 2" x 6" extruded rectangular aluminium tube instead. My idea (not as original as I thought after doing some googling it, someone's always stealing my ideas before I think of them, lol) is to cut and taper each end to remove the corners and then weld it up with a 1/2" fip fitting at each end.

If it works, I'm thinking of making 7 more to fill my grow space, connect them together with either pex or vinyl tubing, which will go to a heat exchanger consisting of a used car radiator and a box fan set up outside the grow room. So question is, has anybody seen or had any xp with a similar design, and does this sound like it will work? Not sure what kind of flow rate I'll need, so I'll probably get a variable speed circulating pump, but any advice or critique is appreciated ;?)

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ttystikk said:

Use Pex. Otherwise it's a solid design.

I'd also suggest using a manifold downstream of your pump to split water between your rails, use valves before and after each one, and another manifold to gather the return lines.

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Airwalker16 said:

I'd think by the time it gets to the end one, it'd be pretty Frickin hot. The last bar or few, might have issues. Just because it's absorbing so much heat from each individual bar before reaching the last 2 or 3 of your 8.

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Airwalker16 said:

So you saw the problem I mentioned and avoided it by manifolding water, split, directly In to each one. Nice.

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Airwalker16 said:

Fuck you, bitch. You're such a fucking troll. I was simply giving him my opinion. Suck my cock.

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