How to demagnetize a blade?

T

THG

Joined
May 18, 2008
Messages
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I flat-ground one of my knives using a belt sander, and I guess all the static or the constant grinding or both caused the blade to become magnetized.

I've tried smacking the blade with a screwdriver, but it didn't do anything. Heating the blade up will ruin the heat treating... Is there anything else that can be done to demagnetize it?

Thanks.
 
THG said:
That won't ruin the heat treating?
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Nope. The microwaves will scramble the polarity of the atoms yielding a magnet free blade.

They do this in spy shops and dentist offices to routinely demagnetize tools.
 
Josh K said:
Stick it in a microwave for a couple of minutes.
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This is not recommended with a kitchen microwave. Won't hurt the knife. Might fry the microwave.
 
knarfeng said:
This is not recommended with a kitchen microwave. Won't hurt the knife. Might fry the microwave.
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Sorry, sarcasm doesn't read too well. I would highly advise against putting any sort of metal into a microwave.

Bill DeShivs said:
Just whack the blade sharply against hard object.
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This was discussed elsewhere and someone said that you had to pound on it for a while while it was oriented east / west.
 
Bill DeShivs said:
Just whack the blade sharply against hard object.
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I've struck it with a screwdriver, but I'm afraid to do anything more; I don't want to fracture the blade or deform it. Or break the lock... Or anything like that.
 
Wrap it in some wire (insulated) and run some AC current through it. No, I'm not joking this time.
 
Josh's solution will work, but you have to pull the knife through the loops of wire in one fluid motion. BTW- the wire will get hot pretty quickly.
Just wrapping the blade in wire with current will create an electromagnet, and residual magnetism will remain when the current is removed.

I demagnitize all the time by rapping tools on a vise. I use a magnetic strip to hold many of my hand tools, so they are always magnetized. One quick rap and they are demagnetized.
 
Never put a metal object in a microwave. It can and will catch fire, and it can extend past the microwave into your house. A family friend caught his kitchen on fire by accidentally leaving a spoon in a bowl of soup that he walked away from after putting in the microwave over for a few minutes.

BAD IDEA.

What's next, homemade cardboard wheels? :rolleyes:
 
Most new microwaves come with metal racks in them. You can put metal in the microwave just not thin metal. A blade might be considered thin. Probably not the best option but a few seconds at a time while being supervisied probably isn't a problem.
 
FlaMtnBkr said:
Most new microwaves come with metal racks in them. You can put metal in the microwave just not thin metal. A blade might be considered thin. Probably not the best option but a few seconds at a time while being supervisied probably isn't a problem.
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You say this as if there were some validity to the claims that this will affect the magnetic state of a knife and therefore a real reason to actually put a knife in a microwave.

The statements regarding putting a knife in a microwave to degauss it were nothing more than someone's ridiculous idea of a joke.

It does not work and is DANGEROUS. Please don't do it!
 
If you live near a radio station, take it by there. They have bulk erasers for their carts. They'll wipe out a cart tape in seconds, and will demagnetize your knife just as quick.
 
I stuck it through the soldering gun once, and that did the trick. Awesome.
 
Surely you or someone you know has a soldering gun. Just pull the trigger and run the blade back and forth through the space between the heavy wires, usually square, that connect the soldering tip to the two 'barrels' of the soldering gun. Presto, demagnitized.

Also second every one else's warnings about microwave ovens. DON'T put metal in a microwave---EVER!! On top on that, I doubt the radio energy from the magnetron tube in the oven would do anything other than heat the blade, possibly ruin the temper, and damage the microwave.
 
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