How did you keep your U-channels together

[TwistedEnvy]

For those of you using Uchannels in LED applications, did you space them or have them right next to each other? How did you secure them to each other in either application?

I was thinking of spacing mine about 1/2" apart using a separator. Would it be best to have a piece of material (whether that be wood or metal) on the ends of each U-channel to bolt these to instead? I am now thinking this may be the better way to go so that I can build the fixture around the LEDs easier. Pics of what you did?

TIA

[mcgyvr]

Thats the great thing about Do it yourself.. Its up to you. A plastic/metal spacer between the channels with holes drilled in legs of the U works fine.. Or a single hole in the bottom of the U channel and another piece at each end perpendicular to the channels works just fine too.

[TwistedEnvy]

I know that is the beauty of DIY, however, this is my first DIY and would love to see how other peoples have come out so far... I am making a sketchup model of what I am thinking of doing. I will post that shortly.

[jimnrose]

I used aluminum strips( 1.5"). I have 5 1.5" x 1.5" x 60" U channels & cross strappped them on a 45 degree angle to avoid conflict with the led locations. Seperating the channels will help with air flow across the channels for cooling.
Jim

[TwistedEnvy]

Do you have any pictures from your build? I am interested to see how you did that- i am a visual learner mostly

[TwistedEnvy]

Here is what I came up with in sketchup

http://i611.photobucket.com/albums/tt192/TwistedlyEnvious/LEDHolder.jpg

My eventual plan is to build a rim of black polycarbonate/acrylic around the LEDs to hide the metal heatsink, etc... The angles would give me something to attach the polycarb/acrylic to when i get to that part

[Mr Smiley]

I like this. And you can suspend this with hangers from your folded up corners.

[TwistedEnvy]

That's true. That is one thing I have been struggling with though. My significant with a u other does not want me to hang this light from the ceiling. I get where he is coming from to a point, but feel that if I find a joist up there where I need it, that would work wonders.

I was going to attach a holder to the wall behind the tank, however, I don't think that scenario would work anymore because the tank is at least 12" away from the wall now. I cannot attach the rod to the back of the tank stand because of a lip on the stand.

Any ideas on this front?

[kcress]

You need a gap between them. 1/2" is enough.

[terahz]

How did you secure them to each other in either application?

with more u-channels.

Not the same setup as what you're doing, but close:
http://joro.geodar.com/pics/albums/40B/normal_40B_057.jpg

[MarkGP]

with more u-channels.

Not the same setup as what you're doing, but close:
http://joro.geodar.com/pics/albums/40B/normal_40B_057.jpg

If you are planning on this many leds over a short span of u-channel, you might want to rethink this and get a heatsink! This will get too hot and you will be too dependent on fans to keep things somewhat cool.

[jimnrose]

If you had a wider U channels then the LED's would be mounted directly to the aluminum and be an ideal heat sink. In my case I'm running my leds at 2 watts each and the channel temp is 20 degrees above the water temp.

Acrylic warps severely in a humid environment. Polycarbonate is much better but avoid using it to shield the led's because most polycarbonates have a UV blocker thereby cutting off light around 450nm which is bad news for royal blue (violet) wavelenth.

I mounted my led's 4" above the water line (without optics). The light diffuses fine but 5" would have been better for maintainance access.

LOL, Jim

[TwistedEnvy]

If you are planning on this many leds over a short span of u-channel, you might want to rethink this and get a heatsink! This will get too hot and you will be too dependent on fans to keep things somewhat cool.

I think he is using individual CPU heatsinks on the back of every LED, then attached those to the uchannel. I may be mistaken. I have 5- 2" wide uchannels and that means I will have 12 LEDs on each one.

[hebygb]

I saw this demonstrated at a RV show a couple of weeks ago... This is perfect for welding those aluminum heat sinks, rails etc... This stuff is easy to use works on any non magnetic metal and all you need is a propane torch.

http://www.weld-aluminum.com/

[halcyonism]

I saw this demonstrated at a RV show a couple of weeks ago... This is perfect for welding those aluminum heat sinks, rails etc... This stuff is easy to use works on any non magnetic metal and all you need is a propane torch.

http://www.weld-aluminum.com/

Harbor Freight sells those brazing rods for quite a bit cheaper then what is listed on that web site.

They apparently work great, unless you need to do small welds which are close together. This is due to the fact that once the metal reheats the material will liquefy again.

[hebygb]

extremely strong welds. And yes they were selling the rods for half price at the show... $35 a tube. anyway, makes for a real nice clean heat sink arrangement. May even be able to break out of the standard rectangle.

[hvacman250]

If you are planning on this many leds over a short span of u-channel, you might want to rethink this and get a heatsink! This will get too hot and you will be too dependent on fans to keep things somewhat cool.

Mine doesn't. My Cree's are mounted 3" on center; I have 72 LEDs. With NO fans blowing, the hottest place on the u-channel is 92*. With a 4" Radio Shack fan, its 86*.

I saw this demonstrated at a RV show a couple of weeks ago... This is perfect for welding those aluminum heat sinks, rails etc... This stuff is easy to use works on any non magnetic metal and all you need is a propane torch.

http://www.weld-aluminum.com/

Its AlumiWeld at Harbor Freight. And if youve never welded or brazed before, buy scrap to experiment with. Make sure the aluminum is sparkling clean, don't overheat it, and go slow. It's definately tricky.

[TwistedEnvy]

that is an interesting thought as well. But someone said you need space in between them....that wouldn't work if you weld them together

[hvacman250]

I made a rectangular frame from 1" square tubing. Welded the u-channel across the square tubing, spaced evenly.

[terahz]

If you are planning on this many leds over a short span of u-channel, you might want to rethink this and get a heatsink! This will get too hot and you will be too dependent on fans to keep things somewhat cool.
I've been running this setup for 7 months now. Passive cooled. LEDs don't get above 115F (~46C) which is quite good IMHO. But I was just pointing out "how to keep your U-channels together".

I think he is using individual CPU heatsinks on the back of every LED, then attached those to the uchannel. I may be mistaken.

You're not. The black squares are Power PC heatsinks. One of them is adequate for a single LED even at 1A current. The u channels just add to the cooling.

[jeffs86GT]

my plan is to use just regular "L" aluminum at the ends. Probably end up using rivets or SS hardware to connect the "L" to the "U".

Jeff

[jeffs86GT]

http://www.reefcentral.com/forums/picture.php?albumid=3812&pictureid=26051

Took a snapshot of my sketchup.

Jeff