How to demagnetize a blade?

F

Frantium

Joined
Mar 25, 1999
Messages
526
OK this is silly. I was working around speakers and subwoofers (with strong neodymium magnets) with my Sebenza about a week ago. In two or three occasions, my knife would just stick to the magnets because I worked so close to them. Just a couple of days ago, I realized that the blade had this strong magnetic force around it. This is really disturbing. Not that I work for EOD or anything, but everytime I try to make a precision cut say in a tight spot surrounded by steel, my blade will just stick left and right. If I place a paper clip on a table about 1 1/2 inch away from my Sebenza, the blade is strong enough to draw the clip (sigh). Any ideas?


------------------
Reynaert
Fayetteville, AR


 
You could try a bulk magnetic tape eraser, my guess is though that the blade hass too much mass to be demagnetized that way.

You might give a call to a few machine shops and ask if they have a magnaflux (?) machine. I used to work in a engine shop and they used one of those to check for cracks in crankshafts. The upshot is it had a large ring to degmanetize the crank after it was inspected. Would work fine I think for your knife.

DaveH
 
You could try a bulk magnetic tape eraser, my guess is though that the blade hass too much mass to be demagnetized that way.

You might give a call to a few machine shops and ask if they have a magnaflux (?) machine. I used to work in a engine shop and they used one of those to check for cracks in crankshafts. The upshot is it had a large ring to degmanetize the crank after it was inspected. Would work fine I think for your knife.

DaveH
 
According to "The Truck Guys" (not the right name of the show, but something like that):
They magnetized a screwdriver with a speaker magnet, and then *de-magnetized* it by holding it to the other side (pole) of the magnet.
So, just slice into those speaker cones and you'll be fine!
smile.gif

Seriously, materials can be demagnetized by placing them in an opposite mag field (as above), by placing them in an oscillating mag field (bulk tape demagnetizer and the like) or by heating them up. I don't recommend the "heat" one for a knife
smile.gif
and the "opposite field" method will be hard to do with the large surface area of the blade. Some areas could be magnetized in one direction, some in another, some not at all.
So, head on down to the machine shop or video studio.
Sorry to be so long-winded. Good luck!
 
DaveH,

I sure will try that magnaflux gadget if I can find one. I already contacted a friend about magnetic tape eraser too. Gonna try it this weekend. Thanks for the suggestion.

Wolf,

So, just slice into those speaker cones and you'll be fine!
Click to expand...
NOT!! No can do man. First the speakers are far more expensive than my Sebenza. Secondly, they're not mine
smile.gif
. I already tried demagnetizing my blade by applying 'opposite field' method. And yes, it was difficult
frown.gif
.
 
Clock and watch repairmen have demagnetizers; they have to demagnetize tools as well as parts. If you have a bulk tape demagnetizer handy that should do it too. I don't think a head demagnetizer will do it, not in reasonable time anyway; it's too small.

The way a demagnetizer works, by the way, is to run high-frequency alternating current through an electromagnet so the sign of the field changes rapidly. You gradually move the tool away from the coil, and the magnetization of the tool keeps changing polarity back and forth and getting weaker as you move away from the coil.... Moving it slowly and smoothly gives best results. Of course demagnetizing your knife is not a critical application; as long as you get it sufficiently demagnetized that iron filings won't stick to it you'll be satisfied.

-Cougar Allen :{)
 
Our company makes available some small tools, about 3in square I guess, to magnetize and demagnetize tools like screwdrivers, by placing the tool in one of two dfifferent holes. I think that 'Wiha' is the brand, and they're German.
 
Johno,

I'm familiar with Wiha, especially their torx drivers (gotta have those, one of the best out there). What do they call this magnetizer/demagnetizer thingy?
 
You must log in or register to reply here.
Back
Top