Introduction: Giant 100mm LED

This is a hand made 10x scale model of a 10mm LED that gives off light via 3 one watt LEDs inside a custom made resin cast (made by me) that also has a Pulse Width Modulation (PWM) light dimmer. To set the cast I first had to create a wooden form of an LED and slather silicone on to create a mold so that I could pour resin into it.

If you have any improvements that you like to be made note of, please leave a comment!

This is part of the Craftman contest, so if you liked this instructable, please vote for me between january fifth and eleventh by hitting the vote button in between those dates (a vote is different than a rating, but ratings are welcome too ;) )

I give you one of the world's largest, DIY LED.

Step 1: Table of Contents

This is a somewhat complex instructable involving the following skills:
--soldering/electronic knowledge (Must know how to read schematic, but if you cannot, please ask questions by leaving a comment)
--Wood work (need to be able to use the following: lathe, coping saw, various sanders, drills, etc)
--Resin Casting (This was my first real time casting anything, so don't worry about it)

I have broken this instructable up into the following:

--Forming the Wooden LED: steps 2-10

--Making a Mold of the Wooden LED: steps 11-12

--Electronics: steps 13-16

--Casting the LED: steps 17-20

--Finishing Up: steps 21-23

Step 2: Materials for the Wooden LED

For forming the "head" (The epoxy part of a normal LED, the thing that kind of looks like a bell) of the LED you need:

various lathe tools
Coping Saw
Vibrating Sander
Belt Sander
Chisel (or some tool to scrape off glue)
Radial Arm Saw (or some other way of cutting up the pine board)
Putty Knife (optional, but nice)

1" x 6" x 8' piece of pine
Wood Glue
Paper towels

Safety Glasses (necessary), ear protection (highly recommended), Respirator (highly recommended, especially while sanding)

Step 3: Cut the Board

You will need to cut your board into 8" segments (you need about 6-8 segments). The goal is so have an 8"x5.5"x5.5" block. The 1" thick wood is really about 5/8ths, and 6" wide is more about 5.5" (it's because the dimensions are pre-processing).

Step 4: Glue the Wood

Now that the wood is cut into 8" segments, we must glue them together into a ~5.5"x5.5"x8" block of wood that can be turned down on the lathe.

Spread a thin layer (don't just slather it on thickly!) of glue on both sides of each sawdust-free (this is important) board and clamp them together. Have a dry run before you glue the wood, put the worst pieces of wood either in the middle or on the outside (middle so it's hidden, outside so that it'll be turned down into sawdust). Put down paper so you won't get glue on your clamps and/or workspace.

Also, all wood is warped, since all of these segments are from the same board they should all bow the same way. Make note of this while clamping, have all of the pieces of wood bow the same way so that there will be a smaller gap in between segments, thus creating a stronger, cleaner joint.

Once the Glue is dry, scrape off as much excess glue as possible; the glue is harder than the wood and will dull your lathe tools faster.

Step 5: Mount It on the Lathe

From this point on I will be using millimeters and centimeters as my main unit of measure because LEDs are metric, and so will this one. I only used Imperial units before because that's what all of the wood in the US works off of.

If this is your first time using a lathe, you should probably read a tutorial somewhere; I believe the lathe is a very safe tool, but can turn very deadly if you don't know what you are doing.

Draw an X on each end of the block of wood to find a crude center.

This Block of wood was too big for my lathe, so I (well, my dad) had to cut off some of the corners (wood that would have been turned down anyways, I didn't take off any useful wood).

Step 6: Turn It Down

Using the Gouge, turn the block of wood into a cylinder. Then use the flat tool (along with the gouge) to make a uniform cylinder that has a diameter of 11cm. If you don't have a caliper, you can use a c clamp with a ruler (that's what I used).

Once turned down, take your ruler and mark off a 14cm section; this will be the overall length of the LED. From the left of that section, mark off 2cm and 10cm.

See picture for what each part is for.

Step 7: Carve It Into an LED

First off, do not turn down the 2cm section, this is the lip and it's diameter is 11cm, which the cylinder already is. Using a gouge, bring down the excesses to the smallest diameter that your lathe can handle/you are comfortable with. Next bring down the biggest section to a constant 10cm. Bring down the last, right most section (besides the excess) to 10cm and round it off starting from the end of the 10cm constant and the left mark of the excess. If you are confused, please consult the picture.

When you're done sand it down with some fine grit sandpaper and put some finishing wax on, I'm not sure if it's necessary, I just did.

Step 8: Cut and Sand the Nubs

I don't know about most modern lathes, but mine leaves little nubs I have to cut off. Normally I'd do this on my bandsaw, but the LED was too big for it, so I had to use a coping saw. Cut them off as close to the LED as possible. for the nub by the curved down part, using a vibrating sander. For the nub at the base, use a belt sander.

Apply more wax to the newly sanded parts.

Step 9: Find the Center and Drill

Now that you've cut and sanded down the nubs, you have a wooden version of the LED head!

Now we have to find the center so that we can drill 2 holes equidistant to it for the legs of the LED. This is probably not too necessary (because you won't be covering the base in silicone later, unlike me). Instead of following steps 9 and 10 you could just drill a hole in the vague center and insert a dowel rod (to give it support while creating the mold)

To find the center of a circle you need a ruler and a right triangle. Draw a random triangle into the base of the led and find the center of each line. Using the right triangle, draw a line that is the perpendicular bisector of each of the triangle's sides. They should all converge to a central point which is the center of the circumscribed circle, the LED. Geometry class actually helped in a real life situation! Who would have thought?

Now that you have found the center, draw in the diameter. Drill 2 (5/16) holes along the diameter, each 1.5cm away from the center.

Step 10: Create LED Legs/support

Cut 4 pieces of tube. to find the length, take 30cm and add however many cm that the tube can go into your base (these pieces of aluminum tubing are going to become the leads of the LED). In my case, their length was 32cm.

Using super glue (or any other good strong glue), glue the tubes into the wooded LED.

You are now done with all of the wood work, yay!

Step 11: Making the Mold

Since I had to make the Instructable with materials that could be bought from local stores (due to the Craftsman Contest deadline), my materials are less than ideal, but they worked!

Go down to a store such as Home Depot or Lowes (I went to Lowes) and pick up a 4 pack of Silicone Caulk. Along with this you need about 5ml of Glycerol (I had 10mL). Supposedly this makes the Silicon caulk better for making a mold (I found this info here), and I used 2.5ml of glycerin per canister of caulk (about 10.1 fluid ounces).

Make sure you mix the silicone and the glycerin well! Slather it onto the wooden LED. I also sealed the base, but later this only caused more headache, so I recommend not putting any silicone on the bottom. Also, make sure you put enough silicone on the lip (it's easy to only put a thin layer there, which will rip later, like mine did)

I made the complete mold in 2 layers, using 1 can per layer.

WARNING: This stuff smells really, really bad (imagine a vinegar smell that's like 100x more powerful and burns your eyes and throat). Use with proper ventilation.

Step 12: Extracting the Wooden LED

Taking the LED out should be simple (if you didn't slather silicone along the base, unlike me). While pealing the mold away from the wooden LED you pull it inside out, so you have to flip it outside in.

Step 13: Electronics Parts

You should have some electronic expiereince, but it's not necessary.

Electrical Components Needed:
(1x) 555 timer
(1x) 0.1uF capacitor (usually ceramic)
(1x) 100k ohm linear potentiometer
(1x) knob for the potentiometer
(1x) 33k ohm resistor
(6x) 10 ohm resistor (1/4 watt or better)
(1x) 3.3k ohm resistor
(1x) 510 ohm resistor
(1x) 0.25 inch knob
(3x) 1 watt white LEDs (usually these come on a star PCB)
(1x) switch (should come with the lamp you are using for a base)
(1x) npn transistor (I used a 2n4401)
(1x) diode (I used a 1n4148)

NOTE: resistor values can be changed, just be relatively close to the values I give (except the 10 ohm resistors, don't use any other values)

Step 14: LED Driver

The Driver I created for this LED consists of a current limiting resistor (a couple of series and parallel resistors) and a 555 timer chip pulsing the LEDs at different duty cycles, making it appear lighter or dimmer.

I'm going to assume you know how to solder. If not instructables offers a large array of how-to soldering instructables.

I personally soldered in the air (not using a circuit board/prefboard) simply because I didn't feel like cutting out a prefboard and mapping out where all of the leads go.

Step 15: Mounting the LEDs

Mount the LEDs on a little strip of aluminum with some thermal glue. These LEDs can get fairly hot, and even hotter in solid resin, so we need as much cooling as possible (the heat will be fed along the tubes later), which is probably not enough as I should have. Make sure you orient them in an easy to solder in series format.

I've also included some pictures of 1 (just one!) LED on.

Step 16: Drill and Glue the Tubes

Drill a (1/8) inch hole (maybe a bit bigger, up to you) near the top of each tube, the wire leading to the LEDs are going to pass through these tubes.

When the wire is fed through, using the thermal glue again, glue the tubes to the base of the aluminum that the LEDs are glued to.

I added more glue later because the original amount wasn't enough to keep it sturdy.

Feed one wire through per tube.

Step 17: Materials for Casting the LED

--48 fluid ounces of clear resin (If you go to Michaels, this is one big and one small container)
--about 5.6 ml of catalast (or 120 drops, I measured measured how many ml were in 10 drops and I went from there.)
--mixing bucket
--drill and a paddle or just a wooden stirrer (drill is so much easier and faster and safer)
--a way of holding the mold and the LED module

Step 18: Pour the Mold

Put the silicone mold in a beaker or some other apparatus that will keep it upright as the resin is being poured into the mold. Mix 48 fluid ounces of resin with 5.6 ml of catalast. Mix well (this is so much easier with a drill and a mixer, I made one out of a dowel rod glued to a piece of wood). Pour the resin into the mold all the way to the top.

When filled, insert the LED module (being help up by a clamp or tape or anything); make sure everything is straight before you leave it to harden!

NOTE: This stuff smells pretty bad, so work in a well ventelated area (such as a fume hood)

Step 19: Extract the Cast

This is pretty much the same as with the wooden mold, not much to say about it.

Step 20: Polishing

My cast was anything but perfect; it had bumps, depressions, lines, and everything in between. Using a vibrating sander I started at 180 grit (to get rid of all the big stuff) and gradually worked my way up to 600 grit (I didn't have any higher) and then finished off polishing with a polishing compound and a soft cloth.

Various stages in polishing/sanding. I couldn't get out all of the imperfections...

Step 21: House All of the Components

Place the LED driver in the base of the old lamp and instead of having a normal AC chord feeding out, have a wallwart wire feeding into the base (have the wallwart rated at 12 volts and at least 350mA.

Step 22: Insert the LED

Well, how hard could it be? Insert the LED leads into the base and seal with epoxy and/or superglue. Once dry, solder the 2 wires from the LED module onto ground and from the 555 LED driver.

Step 23: You're Done!

Your LED lamp is now finished! You can now test out the different brightness settings and the coolness of the lamp!!!!

I would take different birghness pictures, but it doesn't show up that differently on my camera (some sort of auto-brightness changer?)

Have fun with one of the largest DIY LEDs!
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