Demagnetizer (degausser) drill attachment by Ultor3

Last crawled date: 3 years, 3 months ago

This is a simple, zero-electronics demagnetizer that is powered by a cordless drill and works by rapidly rotating four magnets against the item being demagnetized in order to create strong alternating magnetic field. It can be used to demagnetize tools, erase tapes and floppies (though I'm not sure you'll be able to format such floppy), and similar items.
I have tried it so far on a few different tools like screwdrivers, a caliper and wire cutters, and on a chrome compact cassette, and it demagnetized the tools emough to avoid picking up needles and steel sawdust, and the casette has no audible sound on it even on maximum volume and with headphones, apart from just the tape hiss.
Warning: Using it on any not completely ancient magnetic hard drive will probably erase it thoroughly, but will definitely make it permanently unusable, as there is some boot information and calibration data written to the disk itself, and once it is removed/corrupted, the disk's board can't actually write it to the disk again, so only do it if the disk is going straight to the recycle dumpster and you don't want to sell it or reuse it.
You can also try to use it if your phone's compass got so badly magnetized that it won't work even after properly calibrating it, but do so at your own risk, before considering to do it check on Youtube if you are actually doing the calibration properly, and if you use the demagnetizer, do so only with phone turned off and not from the screen side. And try to avoid the speakers. Most likely nothing bad will happen, but again it might with some unfortunate phone designs and I don't want to be held responsible for that.
Assembly instructions:
You will also need epoxy, best would be the kind with metal particles in it, four strongest 12mm diameter 6mm length axially-magnetized neodymium (rare-earth) magnets, a M3 screw that will serve as the shaft (preferably hex head) and at least 2 M3 nuts (or 3 if the screw is not hex-head), and a piece of steel or iron 2-3 mm thick (one piece is better than a few laminated ones, and any average steel will do, just make sure the magnets stick very hard to it).
Cut a circle (or an octagon if you can't manage a nice circle) 36mm diameter out of the steel, and drill a 3.5mm hole in the middle for the screw. Avoid getting sawdust on the magnets as it is hard to remove, you might want to place a different magnet near the place you are cutting it in, to catch most of the sawdust.
Put the head of the screw if it is hex in the hole in the middle of the rotor. For non-hex screw put one nut on the screw and screw it all the way onto it and tighten it hard, and use that instead.
Put the screw in the hole of the steel circle and add one nut to hold them together, tighten it really hard and then add another nut and also tighten it hard. You need two nuts to avoid unscrewing.
Then insert the four magnets in the holes, so that the poles facing up are alternating if you go clockwise or counterclockwise (so it's S-N-S-N or N-S-N-S). Make sure they go all the way in, they are supposed to stick out 2mm.
Glue the screw and the nuts with epoxy, so that they don't unscrew themselves, and make sure the glue doesn't protrude more than the magnets.
Put the stator around the rotor and make sure it rotates freely. Then lubricate the rotor edge with graphite grease,and maybe a dab of WD-40 to make it more runny, and glue the stator around the rotor, but don't get the glue to the surfaces that touch the rotor. The purpose of the stator is that it is not mechanically connected to the drill, so it doesn't turn when touched against an object, minimizing scratches, as manually holding such strong magnets 1mm from a big piece of ferromagnetic is not easy, especially when the magnets are rotating.
You use it by putting it against the object, then turn on the drill and slowly move it around the object, and then, while still moving it around and keeping the drill active, slowly retreat it from the object (if the object has high permeability so it sticks really hard to the demagnetizer, you can first tilt it at an angle and then slowly move it away. Moving around and away must be significantly slower than drill rotation, otherwise some magnetization may remain.