Introduction: Demagnetizing a Screwdriver
these days, tool companies have found that a lot of people like the handiness of magnetized screwdrivers, so its sometimes hard to find a good set that isnt magnetized. but for some things, such as replacing sensitive electronics like hard drives, its necessary to have a completely demagnetized screwdriver. in this instructable, i'll show you how to demagnetize a screwdriver with heat.
Step 1: Materials
its simple. all you need is a (magnetized) screwdriver, and a heating element. i used an electric stove, but a gas stove, blowtorch, or gas welding torch would also work
Step 2: Start Your Heating Element!
get your element nice and hot. for electric stoves, turn it up all the way. for gas, turn it up so the flame is about an inch long. for a blowtorch or welder, choose your own setting. a little
interesting fact: hot metal (and in this case, ceramic) gives off infrared light, which can be seen by most modern digital cameras. on such cameras, it actually appears as slightly blue or purple, which is why the burner looks pinkish purple in the picture.
okay, so your element is started, now for the fun! you want this to get nice and hot all over, so you need to lay the blade of the screwdriver across the burner in such a way that it touches as much of it as possible, without the plastic handle being too close and melting. i achieved this by propping up the handle with a steak knife, and laying it across the burner, though if you have an open flame, it may be best to point the screw driver up and tilt it into the flame, so its all in the flame.
Step 3: Wait
you need the screwdriver to be very hot for it to lose its magnetism. somewhere around 700°F this temperature is called it's Curie Temperature. however, prolonged exposure to smething really hot will cause it to lose magnetism slowly, so you do not necessarily need it to reach this temp. when you heat up the screwdriver, it will start losing magnetism. but it will also change colors. this is a property of metals, and comes in handy here. first, the steel will turn a straw color, then progress to a bluis color, then to black, then it will form a whitish coating, then it will glow. by the time the tip is a whitish color, all the magnetism will have left the screwdriver!
Step 4: Temper/cool
this step is optional. once you have heated it, the magnetism is gone. but its still hot right? well in this case, you can do what we call tempering. this hardens the metal so it wont bend or disfigure when you use it, likely making it last longer. for this, you need a basin of water large enough to hold the screwdriver's entire blade, with you being able to hold the handle.
first, dip the screwdriver in the water for just a moment. the water will hiss and steam, and the screwdriver will tremble a little bit. you have to pay attention close here, as the heat can make the driver very brittle and might break. you want to wait for the bluish color of the driver to move towards the tip of the driver. when it has, you want to dip the driver in the water and leave it until it stops hissing. wait a few seconds, and the screwdriver will be the same temperature as the water, and cool to the touch. congratulations! you have demagnetized and tempered your screwdriver! if you want, you can use sandpaper or wet aluminum foil to scratch the blade of the screwdriver so it will be shiny again, but this is completely optional.