De-magnetize

its the opposing ends of the file that are magnetized. I've hear of the something like the following: if you get/find another magnetized rod and touch the opposing ends together that they will cancel each other out and thus remove the file's magnetic field.
 
My shop teacher taught me a trick in high school regarding this.

Wrap a wire around the file in a coil from one end down to the other. Touch the ends of the wire briefly to your 12v battery. That will magnetize your item. Since yours is already magnetized, skip to the next step.

To de-magnetize, you need to use an AC current touched to the same coil of wire. If you have an old 12v AC “wall wart” you can snip the connector off and strip the ends of the wires to touch to your wire coil on the file. I would recommend against using line voltage (wall outlet) lol


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I used to magnaflux before I sold the machine. I still have the big AC demag coil and a gauss meter though. A lot of stuff I get back from the NDT shop is still magnetic so I run it through the coil. There are two ways to magnetize parts depending on the direction of magnetism you need. Shooting a strong DC current through the ends of a shaft will give the shaft a circular magnetism. Wrapping a coil around the shaft and hitting the coil with a strong DC current will induce a longitudinal magnetism through the shaft with north on one end and south on the other. In any case the shaft has to be draw through an active AC coil at a slow pace to completely demagnetize it.
 
Mike51Merc said:
Heat kills magnetism, unfortunately it also kills tempering in a file.
Click to expand...

If you are referring the the soldering gun trick, it's not the heat that does the demagnetizing, it's the electricity traveling around the loop. Also, a soldering iron, used for this purpose doesn't get anywhere near hot enough to draw any about of temper out of a file.
 
I bought this simple tool years ago. It did not cost much. Turn it on and drag a tool or part accross it. It does not take up much space. I am sure it is just an AC coil in a box.

John
 

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Many of the soldering guns are induction type so they have a small AC coil. If I hold a shaft in the coil of my demagnetiser, it will heat up too. This old coil is 220 volt so it doesn't take much on small parts. It takes a bit more to demag a crankshaft though. Sometimes I have to pass it through several times or edge the long side up close to the coil & move it side to side a bit. A person definitely doesn't want any residual magnetism in something with any bearing journals. I check every part I send out just to make sure. I always get a kick out of letting my NDT guy know too. It's usually some new kid he hires that screws the pooch. We all learn by mistakes and I've made my share.
 
I was looking around for my Weller soldering gun when I saw
my armature growler buried on a bench.

(Blink) thats a light going on!

Plugged it in and held on tight.
Two passes and the file is back to normal again.

I still want to play with the soldering gun field
on one of the coming long nights.
 
Demagnetizing Nicholson Files

  • Subject the magnetized article to a strong AC field such as a Weller soldering gun open frame transformer.
  • Gradually reduce the field by reducing the gun's input voltage to naught. Either use a variac, or gradually increase the distance by slowly moving the article away from the field so its a good 3-4 feet away from the field.
  • Test by carefully subjecting the file to that vintage Patek Philippe watch your wife just inherited from her favorite grandaddy and see if you can dislodge the balance wheel. Then accidentally click the solder gun next to the watch.
  • Time to get some some exercise.
 
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