Last week I spent a lot of time cleaning on, around, and under my desk in preparation for my post about reusing old ring binders to route cables. In the process, I had to sweep out some neglected corners of my office which, while looking clean enough under ordinary lighting, showed up under photo lights to be harboring colonies of dust bunnies evolved almost to the level of organized agriculture. Working late at night to beat a deadline, I found myself many times peering under a desk or behind a cabinet with a flashlight in one hand and a broom in the other. So, I thought…well, you can probably see where this is going…
Step 1. Take everything apart
I got these USB-rechargeable LED worklights off the discount table at the big orange store nearest my house. They were cheap and chock-full of useful stuff—a USB charge controller board, an 18650 lithium-ion rechargeable battery, and a decent rocker switch—besides the prize: a 6-diode white LED strip that is just the right size to fit across a broom head. My first thought was to just re-skin all this stuff inside a broom, but I eventually decided I did not want to have to worry about figuring out a way to plug my broom into a USB charger when I wasn’t using it. So I paid a bit extra and bought a cheap aluminum LED flashlight, too, to serve as a switchable power supply. If you wanted to save a bit of scratch, you could skip buying the separate flashlight and just hack the worklight guts into your broom and be done with it. Also, I bought two worklights, because I wanted illumination on both sides of the broom, but in use it turns out that’s a bit of overkill—one LED strip on one side is plenty. So you could get away with buying only one worklight and no flashlight. If you go that route, be careful messing around with the lithium-ion battery—those things pack a wallop if you accidentally short one out.
This is your basic aluminum-body high-intensity LED flashlight. This model is nice because the front optics ring is actually a separately machined part that’s threaded onto the body (just like the end cap you have to remove to change the batteries). This makes it easy to remove the stuff we don’t need. Unscrew the optics ring from the front of the body and discard the reflector and lens, then use a small screwdriver to gently pry out the LED, exposing the leads that connect it to the PCB underneath. Desolder or cut the leads off at the PCB pads and stow the LED in your parts box for some other project.
I chose this particular broom—a two-in-one angle broom / dustpan set from Vileda—because it has lots of features that make this hack easier: 1) a “skeletonized” head with a readymade space for running wires; 2) a handle that can be unscrewed for drilling; 3) a plastic fitting at the grip end just the right outer diameter (1″) to fit inside my flashlight; and 4) pleasing colors. To start, unscrew the bristles and set them aside. I discovered you can pop the hanging cap off the other end by pushing it sideways until it breaks, but that turns out to be unnecessary since you have to cut the plug it swivels around off to access the inside of the handle, anyway. A razor saw or hacksaw blade will make quick work of this. Finally, carefully drill a 1/4″ diameter hole in the center of the lower end of the handle where it threads into the bristle, and a matching hole in the whisk, at the bottom of the socket the handle threads into. Check that the two holes line up when handle’s screwed in before proceeding.
Step 2. Mount the flashlight on the grip end
Use a round “rat-tail” file to remove the retaining lip from the front end of the flashlight optics ring, being careful as you work not to scrape up the threads at the opposite end. Once the lip is filed away, screw the flashlight body all the way into the ring, and push the front of the ring over the grip end of the broom. Keep pushing until it bottoms out, then mark and drill three 5/32″ holes evenly spaced around the circumference of the ring. Drill all the way through the aluminum, the plastic, and the steel of the broom handle itself, then install a rivet in each hole. Save one of the rivet mandrels for use in Step 4.
Step 3. Prep the wiring harness
If you want LEDs on both faces of the broom, you need four wires—one positive and negative pair per side. These must somehow connect to the two positive and negative pads on the flashlight PCB, and rather than mess with wire nuts or splices or some other arrangement for splitting two leads into four, I decided to run all four wires the whole length of the broom. I’ve been sort of geeking out about braided cables recently and I thought it would be fun to learn how to braid four wires. Which it was. For about ten inches. Were I to do it again, I would simply cut four 48″ lengths of wire (two red and two black), tie them together in a knot about 4″ from each end, and be done with it. Braiding could be worthwhile for a more visible cable run, but not when most of the length is going to be concealed in an enclosure anyway.
Step 4. Run the wiring
Strip all four leads at one end of the wiring harness, then twist the red leads together and tin them. Do the same with the black leads, then solder them to the negative pad on the flashlight PCB. Solder the red leads to the positive pad, then tape or heat-shrink the four leads at the other end together and tie on a six-foot piece of twine. Tie the other end of the twine to one of the leftover rivet mandrels from Step 2, then fish the twine down the length of the handle from grip end to whisk end, using the mandrel as a weighted leader. Bob it up and down a couple times until you hit the hole, then fish the twine and the wires through. Once you’ve taken up all the slack, thread the flashlight body into the optics ring to secure it at the grip end of the handle. Stuff the free end of the wiring harness through the hole in the whisk socket, then screw the whisk to the handle. Cut off the twine and the tape (or heat-shrink) before going on to the last step.
Step 5. Install the LEDs
Drill four 1/16″ diameter holes through the LED strip PCB, evenly spaced along the centerline between the five central diodes. Align the strip over the bottom edge of the whisk, right at the top end of the bristles, so that it’s angled toward the end of the floor rather than straight out to the side. Use the PCB as a template to drill four shallow 1/16″ diameter mounting holes into the plastic, and secure with four small case screws salvaged from the worklight. Run one pair of red and black leads through the factory mounting hole at the end of the PCB nearest the contact pads, then trim, strip, and tin the leads before soldering them to the pads—red positive, black negative as usual. Repeat this step if necessary to install the other LED strip on the other face of the whisk.
Unscrew the flashlight end cap and load the batteries as usual. I’m using nickel metal-hydride AAAs that I can cycle through a wall-mounted charger when they run down. Screw the cap back on, click the button with your thumb, and the LEDs should come on, illuminating the dark corners of your world, so you can start cleaning them out.