Unwanted magnetism

[David Gilbert]

I've recently noticed that some of my tools and tool rests have become sufficiently magnetized that they stick to each other when I'm turning and I don't like the way this feels. All of the tool rests that I am using are from Robust and I have an assortment of different gouges and most seem to have developed some magnetic properties. All of my tool rests are magnetic to some extent and the tools that I use the most also are the most magnetic. I do have some rarely used tools that show little magnetism. If I assume that the tool rests started out as being magnetic, does moving my gouges along them cause the gouge to also become magnetized? I have magnets in my shop but never allow my tools or tool rests to come in contact with them. Ideas about the cause of this?

OK, now that they are magnetized, how do I remove it? There are commercial demagnetizers but I'm unwilling to spend the money for these. I've pulled a couple of my very small tools through the loop of my soldering gun and that worked but I can't get a 1/2" gouge to go through without touching.

Ideas?

Cheers,
David G

[Mel Fulks]

Would the old tape deck demagnetizers work? Plenty of cheap ones on ebay.

[Robert Willing]

Try this trick. Lay one tool at a time on your (wood bench not metal) bench. Take your soldering gun and and press the on trigger do a circular motion (about 4" away or closer) about 4 times over the tool keep this motion up until you are about 4' away and swing the soldering gun at right angle to what you started out at and simultaneously release the trigger on the soldering gun to turn it off. This is how we use to demagnetize a picture tube (CRT) back in the day. This actually demagnetized the mask in the color CRT.

Try this on your tool rests as well but do it several turn over the rest. (more mass in the tool rest) Back in the day it was claimed that the motor in a vacuum cleaner would make the mask magnetized causing a blotchy color field or purity of the color field. You may be leaving your tools in a magnetic field and not know it.

[Glenn C Roberts]

Dave & Robert, What if you took a length of #12 or #10 copper wire and made a loop for the larger tools to pass through?

[kevin nee]

Can tools become magnetized by holding them on a magnetic tool holder from Harbor Frieght ?
i just put up a magnetic strip to hold tools by the lathe.

[Brice Rogers]

A variety of thoughts:
1. The earth's magnetic field magnetizes things (slowly), especially things that are held in that position for long periods of time. Also, using magnets to hold tools will magnetize them more quickly.
2. There are a variety of "how to" articles and videos on how to take apart a transformer or a motor to make a demagnetizer. I like the motor idea because it would seem that you could pass larger tools through.
3. You don't want to make an air coil of 12 ga. wire. The resistance is very low and, for example, the the inductance of 100 turns of wire 4" in diameter is very low - - on the order of one to two milli-henries. If you plug it into a wall socket it is going to draw something on the order of 50 plus amps. You would have a 6000 plus watt heater on your hands.

I'd recommend focusing on item 2 above.

[Scott Hackler]

Can tools become magnetized by holding them on a magnetic tool holder from Harbor Frieght ?
i just put up a magnetic strip to hold tools by the lathe.

Yes, but it won't be very strong on the tool itself. Likely attract metal filings and such after a log time spent on the magnet.

[Wes Ramsey]

I know if you leave a battery sitting on bare concrete it will discharge it. Any chance the same would happen over time with magnetized tools?

[Scott Hackler]

As a general rule of thumb, hand tools will NOT magnetize randomly to the point that you notice the effect. The only thing that would cause a piece of steel to become magnetized would be direct contact with another strong magnet or an electrically induced magnetic field surrounding steel. (remember the old days of making a magnet with a nail, a piece of wire and a 6v lantern battery?) At lease to my knowledge and experience.

The quick fix to demagnetize steel is a sharp blow with or against another piece of steel. It it the method I have used for years to remove the magnetized screwdrivers. A couple swift whacks against the bent vise and no more of that. For tuning tools I would just give it a few taps with a hammer on the side of the tool. If that doesn't work... the tool is heavily magnetized and will either need a de-magnetizing tool or heat (a LOT of heat) but the latter is a no no because of removing the temper of the steel.

The primary issue what, in your shop, is causing them to be magnetized?

[John K Jordan]

I use an old bulk tape demagnitizer on turning tools. If I don't, when I sharpen on a Tormek with the wheel rotating away from the edge each tool will invariably collect a long trail of black steel dust. I don't think this hurts anything but it hides the edge and annoys me. I keep the tape demagnetizer hanging on the wall at the sharpening station.

My tools are never near magnets. How do they get magnetized? I know why, but the last time this came up some science denyer on this forum didn't appreciate it when I described the reason and presented links describing the method and the science behind it. I will just say that yes, they will become magnetized with normal use. Anyone interested in why can research it.

Of course, hanging tools from a magnet can cause them to become magnetized, more so if when removing them they are slid down the magnet instead of lifted straight off. Sliding a tool such as screwdriver over a magnet is a time-honored way to magnetize it.

There is a little used way to demagnetize anything that we used on color CRT screens in the 70s. Works for tools as well. Take a strong magnet and wave it back and forth rapidly while moving down the shaft of the tool, holding it very close to the tool. To keep it from sticking and making things worse, you can put the tool under a thin sheet of cardboard or plastic or something. As you approach the end of the tool, keep the back and forth motion while slowly moving the magnet away. This may have to be repeated several times, possibly rotating the tool, to completely demagnetize something.

JKJ