Just how magnetic are...

[Phil Dwyer]

...your knives.

We know some of you knife makers are friggin magnetic (we won't name names), but I'm talking knives.

 

[Nathan the Machinist]

...why is your knife magnetic?...

 

[Phil Dwyer]

I'm not sure. It didn't start out that way. I used a magnet to hold it while flat grinding the ricasso and filed the dickens out of it. I was hoping someone here would have had the same experience and illuminate me.

 

[Paul Savage]

hi Phil , just the act of machining the steel will create magnetism in blades. i have a de magnetizer that i got from an industrial supply and always demag my blades. it is a constant pain in the a$$ at work (machine shop) and demagging is an every day part of life. Demaggers can be made from an old electric motor with the armature removed but I'm sorry I can't tell you how to do it as I am electrically challenged.Hope this helps. Paul

 

[Nathan the Machinist]

Ah, I see. You magnetized it. I assume this is a heat treated finished blade? You stand a good chance of fixing it by simply reheating it to tempering temperatures. Heat damages most magnets - so...

 

[Nathan the Machinist]

hi Phil , just the act of machining the steel will create magnetism in blades. i have a de magnetizer that i got from an industrial supply and always demag my blades. it is a constant pain in the a$$ at work (machine shop) and demagging is an every day part of life. Demaggers can be made from an old electric motor with the armature removed but I'm sorry I can't tell you how to do it as I am electrically challenged.Hope this helps. Paul

Huh? Other than using a surface grinder with a magnetic chuck, I have never noticed machining inducing magnetism in work pieces. Am I missing something?

 

[SteelSlaver]

hi . Demaggers can be made from an old electric motor with the armature removed but I'm sorry I can't tell you how to do it as I am electrically challenged.Hope this helps. Paul

We used to use AC solenoid windings to magnetize and demag small tools when I fixed photocopiers, oh, so long ago. Believe AC motor windings would work the same way. Wire a plug and a momentary on switch to the field windings. To magnetize, place the steel inside where the armature was, press the switch and release then remove the steel. To demag remove the steel while the switch is depressed.

 

[Phil Dwyer]

Yes, it's heat treated. Not sure I want to re-temper in the hopes it'll demag. I can look around for an old motor, pull the armature and find an push and hold on switch I guess. Sounds a bit like checking knot holes for squirrels. It's said you gotta make sure to use the right pole.

 

[Bailey Knives]

I picked up a demagnetizer on ebay for about 45 dollars. I think it was supposed to be used to erase cassettes. It works great for demagnitizing knives. I get the same thing if I use a magnet to hold them when grinding.

 

[fitzo]

Nathan, most engravers keep a demagnetizer on their bench to frequently demag their gravers. Otherwise, the chips start to stick to them if they are cutting steel. Repeated impact induces magnetism, so I can imagine there are machining tasks that will, too. Perhaps shaper cutters?

 

[unky_gumbi]

not a good solution for a knife but you can demagnitize most tools by hitting them on a bench or something. I have to do it to my tools at work about every week or 2 because they think its a great joke to stick everyones tools to a bg speaker magnet

 

[JTknives]

the other day i had to demagnetize my digital calipers as little chips where sticking to it. i allways demag stuff after surface grinding it.

 

[Phil Dwyer]

I just spent a buck on eBay for this style small hand held demagnetizer,

I'll see how it does when it get here.

In the mean time I'm going to keep my eye open for a small motor I can McGiver into something like this,

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[sweet]

I was just looking at an old post that I made about a Harbor Freight anvil that I had bought in how to quiet it down from the high pitch ring it makes when hit...I had place these big magnets on it in certain spots which drastically reduced that pitch down to a nice thunk...This was from 2006 http://www.bladeforums.com/forums/showthread.php?t=417619&highlight=anvil and what GlennM said short of it

I got tired of magnetizing everything I forged

All of my blades that I have forged and heat treated myself seem to be magnetized so forget the magnets and go a different route...

 

[David Wesner]

Nathan, most engravers keep a demagnetizer on their bench to frequently demag their gravers. Otherwise, the chips start to stick to them if they are cutting steel. Repeated impact induces magnetism, so I can imagine there are machining tasks that will, too. Perhaps shaper cutters?

I experience the same magnetism problem associated with surface grinding and machining of my workpiece. I have also noticed it while learning to engrave.

One of the first tools I purchased years ago was a demagnetizer. It's still in use, working perfectly. I use it on almost a daily basis to demag tools, workpieces, parallels, etc., etc., and especially a finished knife right before packaging.

It is exactly this one. http://www.use-enco.com/CGI/INSRIT?PMAKA=285-2505&PMPXNO=949785&PARTPG=INLMK3

Can't beat it :thumbup:

 

[Stacy E. Apelt - Bladesmith]

I have magnets on my anvil, and a bunch of them sitting all over the grinding bench. They attract and catch a lot of the filings and grinding dust. The constant magnetic field magnetizes anything I leave on the bench. A quick pass through the demagnetizer solves this.
Stacy

 

[sunshadow]

If you pull the magnet across the blade removing the blade from the magnet you magnetize it. When I was a kid we used to magnetize things by putting one pole of an ALNICO magnet on one end and drawing it down the length, pulling it off and repeating the motion exactly 20 times, I still use that to magnetize jewelers screwdrivers when I'm fixing cameras, to erase the magnetic field you rub the magnet back and forth a few times. If steel passes through the curie point (cooling) in the presence of a strong magnetic field it becomes a permanent magnet

-Page

 

[69_knives]

I guess I need a demagnetizer...

 

[Frank Barron]

Look on ebay for a Tv degausser. its a ring of plastic with a switch on it. I bought mine from a neighbour for 5 bucks, new, well, it was expensive. The trick is to put it over the knife for about 5 seconds and slowly pull it away to a distance of about 4 or 5 feet before you turn it off.

 

[JasonSCarter]

I guess I need a demagnetizer...

I love this pic!