DIY LED lights for Hex - The Planted Tank Forum
 
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post #1 of 14 (permalink) Old 02-21-2011, 04:29 AM Thread Starter
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DIY LED lights for Hex

After much research I decided to tackle making a DIY LED light for my new tank. I owe a lot to Hoppy and others for the knowledge and gumption on LEDs. Of course, I found ways to make it hard anyway.

Parts List:

Heatsink/ structure - 8' of 1.5x0.5 inch aluminum(EBay) $20
15x 3w LEDs (Ebay) $41
Driver (DealExtreme) $14
Various other supplies ~$8 so far

I also purchased some tools, such as a $20 tapping set. I had other things I used, such as a drawer center support which works great (again, thanks to Hoppy for that idea.)


I started by cutting the aluminum to size, and then set up a router jig. I read online about using a router on aluminum, and the advice was to use a slow speed and WD-40 for cutting oil. I figured I would probably ruin a router blade in the process.
It took a fair amount of time, but was actually pretty easy. It actually worked just as well without the cutting oil, and without it the shavings blew away and I had better visualization. And the router bit is still in great shape.





Eventually I ended up with a big aluminum asterisk.



Next I worked on the mounting bracket. The drawer support came with a bracket to mount the slide to the back of the cabinet, so I used it, after trimming the corners of the aluminum to fit it, and trimming the bracket to look nicer.



Mounting the other end to the aquarium stand took a little problem solving, since I wanted it on the corner and the stand was a little wonky. The tapping set ended up being invaluable, as I just put in a couple screw holes that I could screw some clamps to.



I did end up using a counterweight system. It is internal in the clamp, and I just used a screw with a nylon bushing for a pulley on the stationary part of the slide, with one end of the cord connected to the bottom of the sliding portion. I needed about 8 lbs, and Iím still trying to find a neat weight package. A dumbbell worked, but my wife needed it back.

I routed insets for the LEDs. I didn't go too deep, but it should still help so the LEDs are not as visible.
Here i placed one LED in the inset. I need to figure out which LEDs are which before I plaster them in.



I debated a bit one the best way to finish it. I sanded out the extrusion marks with 60 grit paper. It left a rough but very bright finish. I resanded with 220, and it was flatter looking but felt smooth. It would have been fun to go to 600 and higher to make it mirror, but it seemed too much work. So I sealed it with clear lacquer to stop corrosion, and there it is.





Still to come: plastering the LEDs down, soldering them together, wiring in the driver, final assembly.


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post #2 of 14 (permalink) Old 02-21-2011, 05:24 AM
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This is looking great! You really streamlined the drawer slide support compared to how I did it. I suggest verifying that the cantilevered heatsink doesn't sag when the slide is supporting it. I had to add a couple of aluminum "fork lift bars" to my support to stop the sagging, which didn't look good.

Did you polish the surfaces where the LEDs will mount? That is a good thing to do to improve heat transfer from the LED to the heatsink. The conductivity of even the best thermal adhesives isn't good enough if the surfaces are so rough there is a significant thickness of adhesive between the two parts.

Eight pounds of lead used to be very cheap, but the last time I bought some lead it was hard to find, and much more expensive than I ever dreamed it would be. Maybe you could use a tin can filled with rocks, or a sash weight (not that those are easy to find now either.)

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post #3 of 14 (permalink) Old 02-25-2011, 02:50 AM Thread Starter
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Thanks. It really doesn't sag. The whole thing bows minimally when it is up, but the center supports are made to be rigid and support the weight.

I thought about the sash weights. I went to our Habitat for Humanity ReStore, but surprisingly I couldn't find any there. I think it is just a matter of finding someone I know who has it... or I might drill a hole in a rock.


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post #4 of 14 (permalink) Old 02-27-2011, 10:23 PM
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That looks awesome, love the router work. Any updates?
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post #5 of 14 (permalink) Old 02-27-2011, 11:41 PM
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If you have a buffing wheel laying around, some jeweler's rouge and a thousand RPM can VERY quickly put a mirror shine on that.

I have a lathe that I use for such things and I buffed my heatsink on it quite quickly.

If you need 8 pounds of lead, see if your local tire store will give you some old tire weights. The rest is up to you and a little imagination.
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post #6 of 14 (permalink) Old 02-28-2011, 01:35 AM
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Quote:
Originally Posted by redfishsc View Post
If you have a buffing wheel laying around, some jeweler's rouge and a thousand RPM can VERY quickly put a mirror shine on that.

I have a lathe that I use for such things and I buffed my heatsink on it quite quickly.

If you need 8 pounds of lead, see if your local tire store will give you some old tire weights. The rest is up to you and a little imagination.
Then buy a blow torch and a good steel ladle and get some casting sand so you can cast the shape you want Or, just buy a chunk of lead at a good well stocked plumbing supply store. Another option is big fishing weights.

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post #7 of 14 (permalink) Old 02-28-2011, 03:07 AM
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Well if you just need a mold, a piece of cheap electric conduit or similar metal piping would work (with a cap on the bottom). Just dip a loop of coat hanger wire, or a big eye-bolt, into the hot lead before it solidifies and you have a hanging hook.

A 12" height of 1.5" diameter steel pipe should net out (ballpark) 8 pounds if my calculations are correct. Keeping in mind that tire weights are a lead alloy that isn't as dense as elemental lead.... and accounting for the weight of the steel pipe, which would remain intact.

I make pyramid and egg fishing sinkers all the time from recycled lead. I love playing with molten metals lol.
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post #8 of 14 (permalink) Old 02-28-2011, 05:06 AM
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Quote:
Originally Posted by redfishsc View Post
Well if you just need a mold, a piece of cheap electric conduit or similar metal piping would work (with a cap on the bottom). Just dip a loop of coat hanger wire, or a big eye-bolt, into the hot lead before it solidifies and you have a hanging hook.

A 12" height of 1.5" diameter steel pipe should net out (ballpark) 8 pounds if my calculations are correct. Keeping in mind that tire weights are a lead alloy that isn't as dense as elemental lead.... and accounting for the weight of the steel pipe, which would remain intact.

I make pyramid and egg fishing sinkers all the time from recycled lead. I love playing with molten metals lol.
Any chance you could do a DIY thread on making lead weights? With photos? I'm not sure how well it fits into planted tanks, but this is one planted tank project where it would be relevant.

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post #9 of 14 (permalink) Old 03-05-2011, 02:51 AM
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How about a progress report?

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post #10 of 14 (permalink) Old 03-07-2011, 01:38 PM Thread Starter
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The fixture is finished, but I need to take photos. The wiring/ soldering worked on the first try, with no bad LEDs.
I was at my brother-in-law's, and he had 8 lbs of lead bean-bag-type sash weights sitting on a shelf in his basement, so that problem was solved for free!
I'll try to take pictures in the next few days.


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post #11 of 14 (permalink) Old 03-07-2011, 10:27 PM
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Quote:
Originally Posted by Hoppy View Post
Any chance you could do a DIY thread on making lead weights? With photos? I'm not sure how well it fits into planted tanks, but this is one planted tank project where it would be relevant.
I couldn't do a pic tutorial right now, my fishing sinker casting stuff is packed up for a while. There's no fish to catch in Raleigh lol, and I only head to the coast once a year, so I'm stocked up for a LONG time lol.


Essentially it's quite easy.


1) Purchase proper size metal pipe/conduit from Lowes, cut with a pipe cutter or hacksaw.

2) Buy one of those cheap single-burner stove doodads that is rated for at least 1,000 watts. Preferably higher, or it will take eons to melt the lead. I used a stainless steel scrap cooking pot with a wooden handle to melt the lead. Cast iron is fine too but takes longer to heat up to melting temp.

3) Select lead choice from wherever you want. Don't try to melt a ton of lead at once... melt a LITTLE bit (enough to cover the bottom about 1/4").

4) After 20-30 minutes the lead should be hot enough to add more, SLOWLY AND CAREFULLY. Use a metal ladle with a wood handle to add the lead.

5) After it's melted, jam your pipe into the ground about 1/4" and keep it as level/plumb as possible. This is your bottom.

6) CAREFULLY and SLOWLY pour the lead in. Go to fast and it may vapor lock on you, superheating the air in the pipe and blowing the hot lead out of the top. Wide pipe helps reduce this.

7) After a bunch of ladles of melted lead are poured in to the pipe, have an eye-bolt handy to poke down into the last ladle worth of lead. Hold it in place with pliers, pour the lead around it, and let it harden.

Done.


You can get calculators on line to calculate the weight of any given volume of lead. Just find the density of lead (or whatever material) in cubic inches (or cm), and then calculate the volume (in cubic whatevers) of a cylinder, and thus you can derive the needed size of pipe. Takes a bit of work, but it worked like a charm when I made some 14 and 18 ounce sinkers for deep sea fishing out of steel pipe.
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post #12 of 14 (permalink) Old 03-07-2011, 10:28 PM
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By the way, you can probably find an 8 pound mushroom shaped boat anchor for $15-25.at any given boat place, or many Wal-marts.

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post #13 of 14 (permalink) Old 03-11-2011, 02:56 AM Thread Starter
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So I finally took some pictures. Pardon my messy basement.
The weight:



The light on and raised:




The mounting bracket:











Finally, here is the start of what will be going in the tank:


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post #14 of 14 (permalink) Old 03-11-2011, 03:21 AM
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Very interesting design! It does look like some of the wires sag down so you can see them. I used dabs of aquarium silicone sealant to keep my wires from doing that. Did you get a PAR meter reading?

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