Magnetic blades

joeradza said:
First time I’ve noticed it, but I guess it’s not uncommon. Or is it?View attachment 2122050
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I've got a few that are magnetized, including the Eldon Talley city knife I'm carrying today. I've also noticed that the Boker Nessmi I carry frequently is. The Laguiole isn't.
A quick search came up with this. I'm sure there are other causes also. Been awhile since I studied Physics.

What are 3 methods to magnetize a metal:

How to Magnetize Metal
  • Rubbing the Metal with a Strong Magnet.
  • Striking the Metal with a Hammer.
  • Making an Electromagnet.
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Lots of steels (including stainless) become quite magnetized after certain machining operations, especially things like surface grinding. The parts should be demagnetized after those kinds of operations. Looks like some folks are omitting that step, or possibly those parts snuck through.

Eric
 
I have a small device which will magnetize/demagnetize a tool, with just a few strokes. Sometimes useful for magnetizing a screwdriver. However, I haven't checked my knives, I just came across the one above by chance! :D

Think I sent this one to Charlie ;) :thumbsup:

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ea42 said:
Lots of steels (including stainless) become quite magnetized after certain machining operations, especially things like surface grinding. The parts should be demagnetized after those kinds of operations. Looks like some folks are omitting that step, or possibly those parts snuck through.

Eric
Click to expand...
I suspected that grinding might be a cause. Thanks for confirming, Eric.
 
Way back when I was working , I often had to analyze hydraulic equipment failures and I used this knife to look for metallic pieces and bits . I would occasionally send it back over to the Horizontal Grinder to re-magnetize on his magnetic base plate .
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Harry
 
Occasionally, I've noticed some of my blades have become magnetized after sharpening on sandpaper. I used SiC paper - don't know if other abrasive papers would've had the same effect on the same blade. The swarf from grinding would cling tenaciously to the blade's edge, as if to a regular magnet. It reminded me of when I was a kid and used to drag a nail or something similar through the dirt on the ground, and it'd pick up iron from the soil. I haven't experimented with any means to demagnetize them though. Thought it sort of odd when seeing it, but not enough of an issue to give it much worry. And I think at least some, if not all of them, eventually demagnetized on their own anyway.
 
I have a couple of old straight razors that were advertised as being magnetic- and they are! They supposedly gave a better shave according to some squirrelly science- but shave just like all my others lol
 
This one isn't actually magnetic, (unless it's become so), 'Magnetic' was just one of the trade marks of John Petty & Sons :thumbsup:

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This is the little magnetiser/de-magnetiser I have. Made by Wera :thumbsup:

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It's about 2" across.
 
Some time ago I accidentally discovered that almost all of my knives' blades are magnetic a little bit. I say almost all because I hadn't enough patience to check them all.
 
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