It's built around a magnifier designed as an upscale version of an optical loupe. The magnifier has a clear plastic skirt that is intended to admit light from the sides. I have a small loupe made on the same principal, and it works OK. But I found that with the bigger version, the magnifier casts a shadow on the subject, and not enough light makes it in from the sides. I decided to add some LEDs for better illumination.
In order to make it as bright as possible, and to make construction neat and easy, I used a ring-shaped LED array which is marketed for use as an accent light on automobiles. It's a circuit board 80mm in diameter (just right to fit the magnifier) with 24 surface mount LEDs on one side and current limiting resistors on the other side.
I considered battery-powered options, but I wanted this magnifier mainly for use on my workbench, so I decided to trade off portability for brightness, and made it operate on 110V AC. I used a 3D printer to make a little box on the side to hold the on/off switch and contain the wiring.
I made it at TechShop. http://www.techshop.ws
Step 1: Parts, Materials and Tools
- Carson 5x Stand Magnifier. About six dollars on Amazon. http://www.amazon.com/gp/product/B000Z9HGAS/ref=oh_details_o05_s00_i00?ie=UTF8&psc=1
- Angel Eyes LED module - Be sure to get the 80mm version. I used natural white, but cool white or warm white are also available. Ten dollars.. http://www.superbrightleds.com/moreinfo/led-headlight-accent-lights/led-angel-eye-headlight-accent-lights/49/
- 12V DC wall-wart power supply. I got mine on eBay for about two bucks. The LED array draws about 100mA, but to be conservative you should use a power supply rated at 500mA or more.
- 3D printed switch/wiring box. You'll make this yourself.
- Small rocker switch. The one I found in my junk box fit an opening about 13mm x 9mm. If yours is a different size, you'll need to adjust the 3d model for the switch/wiring box accordingly.
- Hook-up wire, stranded. I used 22 gauge.
- Two 4/40 machine screws, 5/8" long. I used button head screws.
- double sided foam tape
- clear silicone adhesive
- masking tape
- shrink tubing, 1/8" diameter, 1/2" long
- drill press
- handheld electric drill
- drill bits: 1/8", 1/16", 9/64, #60 and #43
- 4/40 tap and tap wrench
- 1/16" hex driver
- soldering iron and solder
- 3D printer
- Drilling guide for switch box holes. You'll make this yourself.
Step 2: Prepare the 3D Printed Components
Print two copies of the switch box. On the Makerbot, I printed them with ABS using 2 shells and 80% infill. This high level of infill is needed because the part needs to be drilled and tapped. Along with the STL file, the original Autodesk Inventor file is included.
One of the boxes will become part of the final magnifier. After any necessary sanding and general cleanup, carefully drill pilot holes for the two screws with the #60 drill. Drill these and all subsequent holes on this part only to a depth of 12mm. Do not drill all the way through. Now enlarge these holes with the #43 bit. Tap both holes with the 4/40 tap. Finally, install the switch, sanding the rectangular hole if necessary.
The other box you printed will be a drilling guide. Again drill the pilot holes with the #60 bit, but on this piece, drill them all the way through. Now enlarge them with the 1/8" bit.
Step 3: Additional Drilling
Put a layer of masking tape on the plastic skirt to avoid scratches. Position the drilling guide where you want the switch/wiring box to be. Hold in place with a clamp, and drill through the clear plastic with the 1/8" bit, using the drilling guide to position the hole.
Before you remove the masking tape, drill holes in the clear skirt to allow the wires to pass from the switch to the LED array. The position of these holes is not critical, as long as the wires end up inside the switch/wiring box. I used two 1/6" holes, very close together. This just allowed my hook-up wire to pass through.
Drill a hole in the switch/wiring box for the power cord, as shown. For my power supply, a hole of 9/64" proved to be a nice tight fit..
Step 4: Initial Wiring and Strain Relief
The LED array came with wires attached, but for aesthetic reasons I preferred white hook-up wire. De-solder the wires that came with your LED array. Strip the ends of two pieces of hook-up wire, and solder in place, being careful to keep the wires and solder as compact and close to the circuit board as possible.
Space will be tight, both in the wiring box and behind the LED array. In order to add strain relief for the wires without taking up too much space, use a bit of silicone adhesive. Strain relief is particularly important at the point where the wires attach to the LED circuit board, because this will be attached with double-sided foam tape, making it difficult to disassemble for repair. Holding the wires in position (I clamped them with a spring-loaded heat sink) apply a small amount of silicone to the wires and the circuit board. Using a toothpick or similar tool, apply silicone to the inside of the wiring box to secure the power lead.
Let everything sit overnight so the silicone adhesive has a chance to cure.
Step 5: Mount the LEDs
Position the LED ring so the it is centered, making sure the wires line up with the holes you drilled for them earlier.
Carefully place the LEDs, and apply gentle pressure to get the tape to stick.
Feed the wires through the holes in the clear plastic skirt.
Step 6: Complete the Wiring
Keeping the wires as short as possible, solder the final connections. Be sure to include shrink wrap as necessary to avoid short circuits.