Magnets for heat treating

S.Knowles

S.Knowles

Joined
Sep 30, 2005
Messages
657
Hello all, I'm having trouble trying working with hamons and got to wondering, I use the little magnet on the end of my carbide scribe to check when my 1095 goes to non-magnetic. What I got to thinking is 1: Do magnets get "burned out" from checking hot steel? And 2: If the little magnet is "rare earth" which are pretty strong for thier size, is it possible that I am overheating my steel prior to quench due to the "stronger" magnet? Thanks, Shawn
 
1. Yes. Heat will kill a magnet pretty easy. Switch them out and test on steel when not hot.
2. Magnetic is magnetic. Once critical, the steel isnt attracted to any magnet at all. Careful with those rare earth magnets and heat. They are actually a ceramic with a thin metal coating, and I believe the ceramic burns some horrid toxic vapors.
 
Some guys pull a magnet from an old car speaker, and put it on the end of a piece of pipe.I put a welding magnet (HF for $3) on the side (outside!) of the forge and just touch the blade to it.If it attracts or sticks,I put it back in the forge.If it doesn't stick,I shove it back in for a few more seconds,pull out,and quench.
 
I get the telescoping "pickup" magnets. Usually at the dollar store. They work pretty good.
 
The magnets I use came from a set of those "fun" magnet construction kits that use a million small 1/8" cylindar earth magnets. I have about 100 of them, and throw one in a vicegrip. After a few HT sessions, I usually retire them. I can noticibly see a difference after that magnet has stuck to a few 1500 degree blades.
 
remember that you have to heat the steel over the temp of the non magnetic stage by a few degs to get the most out of it. and don't waste heat by taking to long messing a round, it don't take long for the heat to drop..a good size magnet shouldn't get too hot from the very short time needed to test the steel.
so that's a new one on me,
if heat will demagnetize a magnet or not.:confused: :)
 
Alnico magnets (looks like steel, often horseshoe shaped) is the most easily demagnetized)

Ferrite magnets - like speaker magnets, are much more resistent to heat

Rare earth magnets - are fairly resistent to heat, but usually they are small so they have little thermal mass and heat up quickly.

I think the easiest and best solution is a relatively large, cheap ferrite magnet from a speaker.
 
Thanks for all the replies, Seems like I'm Ok w/ what I'm using but I'll use some larger speaker magnets i have lying around to be sure. Thanks again. Shawn
 
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