USB Powered Printer Lighting for Lulzbot Mini (or others) Using Eveready LED Flashlight by hemocyanin

Last crawled date: 3 years ago

I have many Eveready 6v flashlights because the price of a battery/flashlight combo ($4.97), is only 29 cents more than the cost of a battery alone ($4.68) at my local Home Depot (FN1). It's really hard to force myself to not buy the combo even though I've got these things coming out my ears by now and I almost always break down and just buy the combo. I've finally found a use for some of my dead flashlights: cheap lighting for my printer!
Basically, for 29 cents I get some LEDs and resistors soldered to a board already drilled with mounting holes, a button, and an unbreakable beer mug (not really of course, I doubt the plastic is food grade). The only other non-printed part needed is one of the many now useless mini-USB cords I have sitting in a box because nothing uses those anymore.
I've uploaded the files in STL and FreeCAD native file format. If you don't have a printer like mine, but do have a stack of these flashlights, I've also included just the button mount for the Eveready button which you can attach to something made for your printer. When printed sideways with the supports in place, the button fits in nice and snug because of the fine bits of support material left over -- you could get away with using no glue to hold it in place. If printed on its back, no support is needed, but you'll probably need glue or epoxy.
My example is printed in natural ABS on a Lulzbot Mini, Cura basic settings, normal (med) quality.
--- assembly instructions (FN2) ---
Removing the LED board: the first thing to do is grab the large conductive ring at the base of the flashilight head, cut through the plastic supports and attachment bits, and break that off. The board isn't screwed down -- instead little melted plastic posts hold it in place. A few snips will allow you to wiggle it free. You'll see where positive and negative get attached -- take a mental note and clip off the positive wire (negative is just a contact spring).
Removing the button: the button is held in place by friction, not a nut. First, remove the rubber weather boot by pulling it off (again, not screwed down). Then, using a flathead screwdriver or something similar, from the inside of the flahslight body pry the switch body down through the hole. It kind of helps to pry along the vertical walls too. You can also try pounding it down through the hole from outside the flashlight body. If you try to use pliers to pull on the switch body from the inside, it will probably split in half, the spring will go sprong and dissapear from the face of the earth, and you won't have a button. Just keep prying with the screwdriver or bash it through. This will take a bit of force, but it'll squeeze out eventually.
Sacrificing mini-USB cord: snip off the useless end, strip outer insulation. Almost certainly, pos and neg will correspond to red and black wires. You can always plug it in and test to be certain. Snip back the data wires, shielding, and anything else (different levels is nice to make shorting almost impossible), leaving just the positive and negative wires. Strip those a little -- red should be pretty short and black fairly long (red will go to one pole of the switch, black to the LED board.
Final Assembly: Break off the four tabs in the button box of the printed part, then feed the USB wire through a hole in the button box of the printed part from outside to inside. Solder the red wire to one pole of the button, then solder another length of wire to the other pole of the button. If the USB cord is loose in its hole, you can add some tape to wedge it in there and it wouldn't hurt to tape over the poles of the switch to prevent anything accidentally running down the USB data lines. Feed the loose positive and negative lines out through another hole, and then slide the button into place. Now you can solder the positive and negative leads to the LED board: red to the positive terminal of the LED board, and black to the negative (big circular pad in the center). The board can then be mounted to the printed bracket with a small screw (FN3).
--- Footnotes ---
FN1: Flashlight/battery combo -- Just the battery. Ridiculous 29 cent difference in price.
FN2: this is for the older 3 LED version. New versions of this flashlight in the store have a single LED. I'm sure it isn't rocket science to get that one out either, but I'm going to wait till the batteries die in my newer flashlights before breaking them down.
FN3: I bought a 1000 of these screws and they're very useful: http://www.amazon.com/gp/product/B00GMQDSRI (I'm not trying to flog this product or push the particular seller -- it just took me forever to find some reasonably priced tiny screws and I spent a lot of money on things that turned out to not be what I wanted, so I thought the link might be useful). If you have different size screws, you can always drill the hole out to make use of whatever you have on hand.