Looking for heatsinks

[sphelps]

Originally Posted by phi delt reefer

+1 - if you can weld the square tubing into a continuous loop or back and forth pattern you can use a "side-venting" fan (possibly called a scroll fan??) to push air through the entire structure and keep it cool. You can effectively cool the entire unit with one fan (unless you have a 6 foot tank )

Yeap or you could use a fan on each tube to make it a little easier or join the tubes with some other means. Not too many people can weld aluminum and contracting it out won't be cheap.

[globaldesigns]

Just wondering, I have look at a few of the DIY LED setups, and everyone has huge heatsinks.

I personally am not using LED, but if LED uses less energy and has less heat creation, why such a big heatsink? Just wondering, as my MH, just have fans with no heatsinks.

[GMGQ]

The heatsink is to dissipate massive heat from the LEDs, which will theoretically extend their lifespan. Each of these little suckers generates a LOT of heat @_@

Just like any electronic component, the hotter it runs, the shorter its lifespan. A good example are CPU's and their honkin' heatsink/watercooling setups. Sure it will still run at the higher temperatures, but are you willing to risk burning it out? I think that's the fear.

Having said that, I do believe these big Amp style heatsinks are overkill for these LED setups. I just finished my 8LED build with a 6"x7" heatsinkusa heatsink, it's about 5lbs. It gets warm to the touch pretty quickly, but I have a 80mm fan sitting on top of it, running at about 5V (it's a 12V fan), and that's enough to cool the heatsink down to slightly cool to the touch.

When I do my next build, I'm using aluminum channels (not u-channel). I think the main thing is to slap on a decent fan to blow away the heat from the heatsinks, so they can continue to suck the heat away from the LEDs. I read that some guys would rather have a big ass heatsink, so that they can avoid adding a fan (due to noise) and just let it air cool. I cant even hear my fan when it's on.

Originally Posted by globaldesigns

Just wondering, I have look at a few of the DIY LED setups, and everyone has huge heatsinks.

I personally am not using LED, but if LED uses less energy and has less heat creation, why such a big heatsink? Just wondering, as my MH, just have fans with no heatsinks.

[SmallFry]

Originally Posted by calgaryreefer

Does anyone know of a place in Calgary or even online within Canada that sells heatsinks large enough to make LED lights, I know there is a couple in the US like heatsink USA, but shipping is pretty expensive, trying to look for local to save and to support our own industries at home!!!!

Thanks.

Wish I had better news, but when I was looking I drew a complete blank - I would've liked to get something locally, or even in Canada but found pretty much nothing. I'm instead going with a large aluminum channel with a smaller one nested inside (thermal grease between the two) and holes drilled in the bottom of the channels to allow air to rise up through instead of stagnating in the bottom of the channel. I will also be using some fans to push air up through and assist convection. I'll make it clear I don't know exactly how well this is going to work since the light is still in the build process - I will be watching temperatures closely during testing. I'm hoping this will work well since my LEDs are going to be fairly tightly spaced.

I'm also interested in the idea of using heat pipes to push the heat from individual LEDs to a number of processor coolers, each handling the heat form a number of emitters - mainly because I'm a bit of a nerd and think that heat pipes are cool.

Originally Posted by globaldesigns

Just wondering, I have look at a few of the DIY LED setups, and everyone has huge heatsinks.

I personally am not using LED, but if LED uses less energy and has less heat creation, why such a big heatsink? Just wondering, as my MH, just have fans with no heatsinks.

LEDs are very efficient at turning electricity into light with relatively little waste heat. That is not to say they don't produce waste heat though. The rub comes in the fact that the emitters are producing that heat in a very small space (i.e. the junction) so the energy density is high, and to make matters worse the junction needs to be kept relatively cool for reasons of efficiency and longevity. For this reason people tend to go for huge heatsinks that can soak up the heat at a prodigious rate in order to be sure those junctions are being kept cool. The bulk heat produced at the end of it will be a lot less than your MH lights which actually have to be very hot in the part of the bulb where the light is produced.

I personally suspect that these heatsinks are a little overkill, but they provide a handy broad flat surface on which to mount the emitters, and after spending hundreds on those emitters a large heatsink seems like a small price to pay for protecting the investment. Bear in mind also that most of these large, flat, finned heatsinks are by necessity mounted in the most inefficient way possible (i.e. flat, fins pointing up) with regard to convective cooling, hence the fans to offset this..


Besides, those big heatsinks just look so cool - especially if you can anodize it a funky colour!

[calgaryreefer]

i went to home depot today and saw some 1"x48" aluminum square tubes that might work, making them like a t5 bar, add enough fans it will work i think, i will try one to see how the heat is, but i suspect it will work really nicely.

[sphelps]

Originally Posted by calgaryreefer

i went to home depot today and saw some 1"x48" aluminum square tubes that might work, making them like a t5 bar, add enough fans it will work i think, i will try one to see how the heat is, but i suspect it will work really nicely.

I recall reading somewhere that 1.25" x 1.25" x 0.125" 6063 aluminum works best for this application.

[mike31154]

You could look around for a place that recycles electronic components, shouldn't be that difficult in a large city. They'll have plenty of heatsinks out of old computers etc. Trick will be convincing them to sell you the stuff rather than ship it off for 'recycling'. I recall when I lived in Ottawa, there was a place in the south end where you could get all kinds of surplus electronics dirt cheap.

Only downside I guess is that your lighting set up might end up looking like something out of a '60s horror movie.

[Ross]

Originally Posted by sphelps

Yeap or you could use a fan on each tube to make it a little easier or join the tubes with some other means. Not too many people can weld aluminum and contracting it out won't be cheap.

Loads of shops weld aluminum.

If your interested in persuing this route, pm me and I'll forward my contact list on to you.

[DiverDude]

The idea of a heatsink is to provide a large thermal mass which has as large a surface area as possible. The larger the thermal mass, the more "sinking" of heat. Most heatsinks have 'fins' since this dramatically increases the surface area exposed to ambient air. The more surface area for a given ambient temperature, the more heat that is transfered to the surrounding air.

Have you tried pricing solid aluminum plate -say, 1/2" thick ? You could make fins 1/4" deep in that with a table saw quite easily.

[StirCrazy]

Originally Posted by DiverDude

Have you tried pricing solid aluminum plate -say, 1/2" thick ? You could make fins 1/4" deep in that with a table saw quite easily.

would be cheaper ordering from the US I think

a heat sink is not as much about mass as people think, here is a def "A heat sink is a term for a component or assembly that transfers heat generated within a solid material to a fluid medium, such as air or a liquid."

a heat sink actually works on surface area not mass, the more surface area the more heat transfer. if you rely on mass then you will adsorb a lot of heat into the material but you won't be able to give it up fast enough and eventually the actual heat sink will get to hot. the fins are to increase the surface area so it can dissipate the heat faster than it builds up. fans can compensate for lower surface area, and increase efficiency as the rate of heat transfer is also a function of the difference in temp between the two mediums.

a hollow square tube 1.25 x 1.25 will disperse more heat than a solid 1.25 x 1.25 bar, because it has twice the surface area, this can even be increased further by supply fresh air with a fan which is increasing the flow over the surface also keeping the air at the surface cooler and increasing the rate of transfer.

the main reason we want to go with the single sided finned aluminum is looks. it is much easier to make it look good, but if you have some kind of enclosure in mine or are retro fitting into a hood then the square tube will work better as it will have a continuous supply of fresh air, where a fin type would be subject to the hood temp unless you vented you're hood with big fans.

the best place in Canada to find single sided finned AL, depends on where you are.. there is a couple companies in van that will bring it in.. probably charge you an arm or a leg though. same as Edmonton ect.. if you are in between like me and don't have the time or money to travel to look for it then you are stuck with metal recyclers, I have both here going to call me when they get what I am looking for in. they had some but it was double sided and I don't have a milling machine to make it single sided yet.

Steve