I had the desire to build a faux-Japanese lamp out of really nice wood and dreamed up this project. I originally envisioned it having four thin dowels crossing the lens for aesthetics, but am more pleased with the way it turned out. This explains the random holes you’ll see on the wood below the lens in the pictures; for inserting the dowels. The lamp is illuminated by a 25W LED and free hangs in my workshop.
I started by carving a groove along the length of one side of the wood using a straight router bit. This holds the plexiglas lens. I then cut the board in to four equal pieces (8″ if I recall correctly) and used a chamfer bit to route a 45 degree angle on the edges of each piece. I cut the plexiglass for the lens by using an aluminum angle as a guide and scoring the plexiglass until I could snap it cleanly. The best way to glue together chamfers in to a box is by putting a right angle (in my case pieces of moulding) on each corner and strapping it all tight using a tie down as pictured above.
The inside of the lamp is painted flat white for minimal loss of light to the box. Outside of smooth mylar, flat white will give you the most light reflectivity. The outside of the box is done in a single coat of semi-gloss polyurethane. No stain, just natural Cherry beauty. I added two square dowels inside the box to aid support of the top panels which were designed for mounting all of the electronics. In the last picture above I am cutting two fresnel lenses to fit on top of the plexiglass. A fresnel lens diffuses light evenly. I collect them by taking apart lcd screens which will typically contain two to six fresnel lenses. You can also get other types of diffuser sheets online from a site like inventables.com
The heart of the lamp is a 25W LED panel from ebay. These things put out a lot of light and get extremely hot. They should never be operated without a heatsink and a fan as they will burn out very quickly otherwise. I use a little bit of thermal compound to adhere the heatsink to the LED. The LED is 36V and 700mA which is a rather tricky rating to get a power supply for under $20. They also come very bulky. I believe that’s why I built the board in the top left of the first picture; to transform a power supply with different ratings. The board on the lower left is taken from a 12v wall adapter and used for powering the fan.
The lamp is hung using eight itty bitty eye hooks and fishing line to connect them. I ripped out the old lamp in my itty bitty workshop and ran the wires into a cheap home depot single outlet adapter for plugging in the lamp.
The end result puts out plenty of light for working under. If you were to use one of these 25W LEDs I recommend not buying one off of ebay, but getting a higher quality US brand for better coloration. The light that comes out of the Chinese ones have a hue to them which becomes tiring on the eyes after several hours. They’re not true cool white.