EcoRenovator - View Single Post

opiesche · 12-31-12, 09:36 PM

OK, so here's the step-by-step description of my process - YMMV, of course, and there's plenty of room to change and improve

Building these fixtures is relatively easy, and the materials come out to about 20 bucks a piece - less if, as I did, you still have a bit of spare plywood and acrylic sitting in your workshop

This is also assuming that you've got 12V wiring and power supply for the LEDs ready. I placed transformers in the walls and rewired the light switches with low voltage wiring (a regular light switch works just as well with 12V as it does with 110).

Materials:

1/4" plywood (about 7 bucks for a 2'x4' sheet)
A strip of acrylic (about $25 for a 2'x4' sheet)
1/2" - 3/4" binding posts and matching bolts (roughly $5 for 10 or so)
Adhesive (~$5 depending on type)
Aluminum L-profile ($6 for a 4-foot piece)
LED modules (Warm White LED Module 12V Waterproof 5050 SMD 4-LED/PCS Light 20pcs $20.95 Free Shipping @GoodLuckBuy.com - $20 for 20 of them)

Before starting to build, it can be useful to make a few calculations for the fixture. How much light do you need? Based on that, what kind of transformer do you need?

Number of modules = number of 15W CFL bulbs * 7
Wattage = number of modules * 0.7

For example, a 15W CFL bulb output about 400-450 lumens. In warm white color temperature, the modules linked to output in the ballpark of 70 lumens a piece. That means for the same amount of light a single 15W CFL produces, you'll need 6 or 7 of the modules.
Each of the modules consumes on the order of 0.7W according to the LED's specs (I haven't measured it), which means for one fixture with 12 modules, the transformer has to handle at least 8.4W, or 700mA at 12V. I've got a 30W transformer in the wall, so I opted for three fixtures with 12 modules each for a total of 25W - it's a good idea to give the transformer a little headroom (on the order of 5-10%), because the power consumption is going to vary a little from module to module.

This is the transformer I used:
Ledwholesalers 30 Watt LED Power Suppply Driver Transformer 120 to 12 Volt DC Output, 3207 - Amazon.com

Now for the fixture:

First, I cut a piece of plywood (I used 1/4") to the size needed for the fixture. The LED modules are about 1.5" square, so anything bigger than that will work - the dimensions really depend on the shape for the fixture, and the arrangement of the LED modules.

This doesn't have to be pretty, as it'll be mostly hidden from view. Painting it the color of the wall before mounting the LEDs will make it nearly invisible. I imagine you could use any other substrate for this as well (like a second strip of acrylic), but the plywood is easy to work with and I had some spare strips.

Drill at least two holes big enough to fit the bolts for the binding posts. The amount and location depends on the desired look and size - the bigger the fixture, the more are needed to keep the cover solidly attached.

Next, I cut a strip of acrylic to size. This should be about 1" bigger in both dimensions than the plywood. To cut, I use a jigsaw because it gives me straighter cuts than scoring and breaking the acrylic - clamp down the acrylic with a board to use as a guide for the saw. Use a fine toothed saw blade and go slow to prevent the acrylic from chipping.

After cutting, clean both sides and spray with frosted glass spray. Two coats is usually enough to get a nice frosted surface. It's a good idea to do this outdoors - not only are the fumes from this stuff pretty gnarly, it also prevents some of the dust undoubtedly floating around in the workshop from settling on the wet spray and messing up the finish

While the acrylic is drying, we can mount the LED modules. They come in a string and can be a pain to mount because you end up pulling the previous one out of position with every one you glue. I can highly recommend Loctite PowerGrab for a job like this - it's got really strong tack while still wet, so the modules are less likely to shift around until the glue is dry.

I squeeze a small amount of the adhesive on the back perimeter of the module and then just press it in place with my fingers. A few pounds of pressure are enough to make it stick well, and they won't move easily after that. Arrange all the modules on the plywood, making sure to not cover up the holes drilled for the binding posts and bolts.

After all the modules are in place, bolt a binding post through each of the holes. The cover will later attach to these.

Now I put the frosted acrylic on top of the binding posts in exactly the final position to mark the holes for drilling. Drill holes through the acrylic where the posts will go - start with a small drill bit, go slow, and use very, very little pressure, otherwise the acrylic will tend to crack. Then expand the holes with a bit matching the size of the bolts. Clamping down the acrylic is a good idea, as it tends to be pulled up the drill bit and slam into the drill once the bit goes through otherwise.

With that, the back end is complete. At this point, I already screwed it to the wall with a few drywall screws and wired it up.

Next, I took a piece of aluminum L-profile

and cut two pieces about an inch longer than the long sides of the fixture. File off the ends to
Put a small amount of adhesive into the inside corner of each L - just enough for a thin layer, so it doesn't ooze out the sides and become visible from the front - then press the frosted acrylic into it. At this point, I weighed it down and let the glue dry for a few hours.

Finally, attach the cover to the fixture by bolting it into the binding posts. Done

In addition to the wall fixture, I've also got two ceiling fixtures built the same way (but without the aluminum profile along the sides) in my office:

12-31-12, 09:36 PM	#6
opiesche Helper EcoRenovator Join Date: Jul 2012 Location: Rohnert Park, CA Posts: 99 Thanks: 4 Thanked 14 Times in 9 Posts	OK, so here's the step-by-step description of my process - YMMV, of course, and there's plenty of room to change and improve Building these fixtures is relatively easy, and the materials come out to about 20 bucks a piece - less if, as I did, you still have a bit of spare plywood and acrylic sitting in your workshop This is also assuming that you've got 12V wiring and power supply for the LEDs ready. I placed transformers in the walls and rewired the light switches with low voltage wiring (a regular light switch works just as well with 12V as it does with 110). Materials: 1/4" plywood (about 7 bucks for a 2'x4' sheet) A strip of acrylic (about $25 for a 2'x4' sheet) 1/2" - 3/4" binding posts and matching bolts (roughly $5 for 10 or so) Adhesive (~$5 depending on type) Aluminum L-profile ($6 for a 4-foot piece) LED modules (Warm White LED Module 12V Waterproof 5050 SMD 4-LED/PCS Light 20pcs $20.95 Free Shipping @GoodLuckBuy.com - $20 for 20 of them) Before starting to build, it can be useful to make a few calculations for the fixture. How much light do you need? Based on that, what kind of transformer do you need? Number of modules = number of 15W CFL bulbs * 7 Wattage = number of modules * 0.7 For example, a 15W CFL bulb output about 400-450 lumens. In warm white color temperature, the modules linked to output in the ballpark of 70 lumens a piece. That means for the same amount of light a single 15W CFL produces, you'll need 6 or 7 of the modules. Each of the modules consumes on the order of 0.7W according to the LED's specs (I haven't measured it), which means for one fixture with 12 modules, the transformer has to handle at least 8.4W, or 700mA at 12V. I've got a 30W transformer in the wall, so I opted for three fixtures with 12 modules each for a total of 25W - it's a good idea to give the transformer a little headroom (on the order of 5-10%), because the power consumption is going to vary a little from module to module. This is the transformer I used: Ledwholesalers 30 Watt LED Power Suppply Driver Transformer 120 to 12 Volt DC Output, 3207 - Amazon.com Now for the fixture: First, I cut a piece of plywood (I used 1/4") to the size needed for the fixture. The LED modules are about 1.5" square, so anything bigger than that will work - the dimensions really depend on the shape for the fixture, and the arrangement of the LED modules. This doesn't have to be pretty, as it'll be mostly hidden from view. Painting it the color of the wall before mounting the LEDs will make it nearly invisible. I imagine you could use any other substrate for this as well (like a second strip of acrylic), but the plywood is easy to work with and I had some spare strips. Drill at least two holes big enough to fit the bolts for the binding posts. The amount and location depends on the desired look and size - the bigger the fixture, the more are needed to keep the cover solidly attached. Next, I cut a strip of acrylic to size. This should be about 1" bigger in both dimensions than the plywood. To cut, I use a jigsaw because it gives me straighter cuts than scoring and breaking the acrylic - clamp down the acrylic with a board to use as a guide for the saw. Use a fine toothed saw blade and go slow to prevent the acrylic from chipping. After cutting, clean both sides and spray with frosted glass spray. Two coats is usually enough to get a nice frosted surface. It's a good idea to do this outdoors - not only are the fumes from this stuff pretty gnarly, it also prevents some of the dust undoubtedly floating around in the workshop from settling on the wet spray and messing up the finish While the acrylic is drying, we can mount the LED modules. They come in a string and can be a pain to mount because you end up pulling the previous one out of position with every one you glue. I can highly recommend Loctite PowerGrab for a job like this - it's got really strong tack while still wet, so the modules are less likely to shift around until the glue is dry. I squeeze a small amount of the adhesive on the back perimeter of the module and then just press it in place with my fingers. A few pounds of pressure are enough to make it stick well, and they won't move easily after that. Arrange all the modules on the plywood, making sure to not cover up the holes drilled for the binding posts and bolts. After all the modules are in place, bolt a binding post through each of the holes. The cover will later attach to these. Now I put the frosted acrylic on top of the binding posts in exactly the final position to mark the holes for drilling. Drill holes through the acrylic where the posts will go - start with a small drill bit, go slow, and use very, very little pressure, otherwise the acrylic will tend to crack. Then expand the holes with a bit matching the size of the bolts. Clamping down the acrylic is a good idea, as it tends to be pulled up the drill bit and slam into the drill once the bit goes through otherwise. With that, the back end is complete. At this point, I already screwed it to the wall with a few drywall screws and wired it up. Next, I took a piece of aluminum L-profile and cut two pieces about an inch longer than the long sides of the fixture. File off the ends to Put a small amount of adhesive into the inside corner of each L - just enough for a thin layer, so it doesn't ooze out the sides and become visible from the front - then press the frosted acrylic into it. At this point, I weighed it down and let the glue dry for a few hours. Finally, attach the cover to the fixture by bolting it into the binding posts. Done In addition to the wall fixture, I've also got two ceiling fixtures built the same way (but without the aluminum profile along the sides) in my office: