I want to magnetize screw bits for my screwdriver.
and wrap the wire around the metal.
What strength of battery should be used? A, AA, D?
For how long should I magnetize the metal to have it magnetized for a good while?
How do I know if my bits contain the types of metals to keep the magnetization (not a soft iron, whatever that means)?
Not really. Just use a big magnet.
It takes a very short period of time (a millisecond, or so, basically the time it takes for the eddy currents in the iron to die out) but it takes a lot of ampere turns. Think covering the metal with a layer of magnet and bumping the ends against the terminals of a car battery. Decide in advance if you will run or use a fire extinguisher if the wire sticks. ;-)
Generally, steel that is hard, physically, (maintains its shape in the presence of large physical force) also is somewhat hard magnetically (retains its last magnetic state).
The easiest way to magnetize tools is to drag a strong permanent magnet along the shaft multiple times, while turning the metal a bit for each stroke. The rare earth magnets that drive the linear motor that positions the heads in hard drives is a cheap source of these magnets. If you don't have an old hard drive you'll never use again, ask around. Somebody you know almost certainly does. Don't worry about taking the thin magnets off their iron pole pieces, just separate the two iron slabs (careful, these things produce enough force that if you get between them, you will bleed) and use one of them on your driver. After that, you will have a pair of refrigerator magnets that you may have to slide off the corner of the fridge to remove.
mercer7 wrote: > I want to magnetize screw bits for my screwdriver. >
We have one of these at work. It works great.
Obviously available many other places.
GG
Battery and coil is doing it the hard way. Take a strong permanent magnet and rub from the center of the bit to one end several times. Keep the same pole of the magnet and rub to one end or the other - not both. Two or three strokes is all it takes - stronger magnets work better.
How long it stays magnetized depends solely on the material the bit is made from.
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A car battery works well, but make sure the engine is running. You only need to touch the wires to the battery for a second.
You can also use one of these:
Don Kansas City
This should work.
It won't work with any reasonable wire or battery.
Get a powerful bar magnet, and stroke the bit repeatedly, in the same direction, hundreds of times, along all 6 sides. That will "nudge" the magnetic domains into alignment, and you'll end up with a magnetized bit.
Usually, the problem is the opposite! ;-)
Good Luck! Rich
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