Degaussing a bench vice

bench vice and now filings are sticking to it.

Repeatedly hitting the vice with a hammer will usually degauss it sufficiently. For really obstinate cases rescue the degaussing coil that is wrapped round the flare of an junk colour TV. Wrap round the vice. Apply power, withdraw slowly (2 to 3 sec). Remove power.

Jim

bench vice and now filings are sticking to it.

Maybe no need. Try heating with a heat gun or gently with your torch. Also, just banging on it with a heavy hammer repeatedly may disrupt the magnetic domains enough. If you try these please report back.

Larry

bench vice and now filings are sticking to it.

Use the speaker magnet. Put it on the other way round, in the same place. Now shim it a mm away, and put it on the other way round, and repeat until several cm clear.

He might just need to find a 125 lb ac powered coil.

I seem to remember that long ago they used to beat on an iron rod oriented in a particular way relative to the earth's magnetic field to magnetize it by shaking the domains loose so they'd line up along the earth's field lines before they settled down again. Your second suggestion would seem counter to that.

Jeff

in a particular way relative to the earth's magnetic field to magnetize it by shaking the domains loose so they'd line up along the earth's field lines before they settled down again. Your second suggestion would seem counter to that.

Tiz true what you say but the magnetic poles produced are very weak. I used to demonstrate this with iron ringstand rods when I was in another life teaching high school physics. Each end of the beaten rod would deflect a compass needle appropriately but the magnetic field of the rod was not sufficient to pickup any iron filings IIRC. For that matter, even,say, a metal file cabinet will become magnetized by the earths magnetic field over time just sitting there. Larry

Interesting thread on the subject here:

I have an old TV degaussing coil like this one... think if I were to lose it, I'd run go find another pretty quick.

(Not my e-Bay listing, just went there for a photo and there it was. There are others too, search on the word deguassing)

Works Great, I open the jaws about 3", turn on the coil and work it over the handle then one side up and between the jaws, then back and up and over the rest of the vice and back.

Be sure to turn on the coil before approching the vice, keep it on the whole time it's near, and slowly pull it a couple of feet away before releasing the switch. The total 'on' time is probably in the 15 second range. If the coil goes off close to the vice or whatever, it can make things worse, depending on the exact instant of switch release. You just have to degauss again if it happens...

Works pretty good on smaller tools too.

I hate magnetized tools, they're always picking up spooge.

Good Luck!

Erik

Do you have an old magnetic tape demagnetiser? Often called a "bulk eraser", they have a quite strong magnetic field. Turn it on, run it over the affected area moving slowly, then pull the demagnetiser away from the vice slowly. Don't turn off power until it's several feet away.

Dave

bench vice and now filings are sticking to it.

The magnet will make it worse!

Have a TV demag coil ? - know someone with one - or a flea market ? Perfect.

You want A.C. magnetic field - from AC current - not DC or permanent magnets.

Martin

The first thing I would try is (suprise) a bulk tape eraser.

Jim

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bench vice and now filings are sticking to it.

Take the rotor and end bells out of a single phase induction motor, then pass the item through the cage several times with the stator coils energized with ac current .....a variac will be very helpful, lest the thing might want to stick to the innards of the cage......

What good would this do? Your heat gun would have to be a nice O/A torch to get it to the Curie temp (circa orange glowing heat).

Tim

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Curie temp is well before it starts to glow.

bench vice and now filings are sticking to it.

You can synthesise an AC field from a permenant magnet by rotating it and moving it further and further away per rev. I have done this often with CRTs, to degauss them after accidental contact with a magnet.

Simply because it tends to be quicker than digging out a degaussing coil.

The Curie temp. for iron is 1418F (770C). That's glowing bright red.

Most steel and iron alloys don't depart from this by a great deal, unless they contain nickel (such as Invar; 36% nickel). Nickel drops the Curie temp. by hundreds of degrees. Invar's Curie temp., IIRC, is around 230C.

Ed Huntress

You do appear to be right. Dunno where I got the idea...

Maybe you were reading the off-brand manufacturing magazines.

Ed Huntress

I don't think you have to get it up to the curie temperature. Why don't you try magnetizing various pieces of iron and steel both by just using the earths magnetic field and by using a magnet. See which materials retain the most magnetism. And then see what will demagnetize them. Heat, vibration, AC field.

If I can get rid of most of the magnetism in a screw driver by orienting it east/west and hitting it against something hard, I don't think it would need to be heated all that hot to accomplish the same thing.

Dan

If you are refering to the earlier post about using the same magnet to degauss the vise, then you should know that an AC magnetic field is merely a magnetic field that alternates north and south at the frequency of the current. A DC field, by comparison, is constant.

Using a constant field, but moving it, will do the same thing as an AC degauss coil, but it will take longer. If you have time on your hands, doing as the other poster suggested is servicable.

Personally, I prefer the bulk tape eraser method to degauss tools. Mine was made by Radio Shack.