Demagnetizing tools.

BigMonster

Native
Sep 6, 2011
1,061
76
Manchester
Hi guys, unusual one. Any idea how to demagnetize tools? My knife and saw make my compass spin and other bits affect it as well. Tried those cheap one demagnetizers:
http://www.hsmagnets.com/wp-content/uploads/2017/04/magnetizer-and-demagnetizer.jpg but they leave a lot of residual magnetism behind so only good for screwdrivers, also size makes them useless.
After passing my compass over most of my gear I was shocked with the results, my belt buckle, pocket knife, KFS set, fire steel scraper etc all affect the needle in close proximity. Is there a cure or from now on I take all my bearings butt naked...
 

BigMonster

Native
Sep 6, 2011
1,061
76
Manchester
How close did you have to hold the compass to the metal to get a reaction?







I know I can stretch my hands out etc. But I have another big concern, storing the compass near this stuff. When the needle is immobilized and exposed to a strong magnetic field it can get messed up. If I swing the multitool past the compass the needle can do 720 before settling down....
 

Janne

Guest
Feb 10, 2016
12,368
2,262
Grand Cayman, Norway, Sweden
I have the same problem with my professional tools..

You can get pro style demagnetizers, but they are expensive. Those small ones you push through your magnetic /object are completely useless. I have tried several. Useless!

I do not keep any steel components close to my compass. Brass buckles, knife on other side of body. Compass in right leg pocket, spare compass in a steel case in backpack.
 

Macaroon

A bemused & bewildered
Jan 5, 2013
7,115
270
70
SE Wales
Have a look for a tape head de-magnifier, should be a yup of them around. They were used for de-magnifying the heads on tape machines in studios, domestic tape recorders and cassette players; about the size of a soldering iron, you just plug them into the mains holding them near the object you want to do and draw them slowly away - job done.

Here's what I mean;

http://www.ebay.co.uk/itm/Analogue-...759248&hash=item5b399136d6:g:jKIAAOSw-vlVjV6b
 
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dean4442

Full Member
Nov 11, 2004
536
2
Wokingham UK
Don't think it's the fact that your knife etc are magnetized, the magnetized needle in thecompass is just reacting to the fact that they're metal.
Colin
 

Robson Valley

Full Member
Nov 24, 2014
8,706
1,643
McBride, BC
The metal has become magnetized.
Hit the end of an iron rod 50 times with a hammer.
Check the properties of the rod.

I should consider the properties of many of my wood carving gouges.
They have been hit many hundreds of times.

My old Recta Prospector compass lives in a steel case which seems to have no influence on the needle.
Still, I'll stack my rifle and pack under a spruce tree and walk out in the open for a compass reading.
Maybe, it's just superstition. That particular experience? My sense of direction was off by 90 degrees.
 

dean4442

Full Member
Nov 11, 2004
536
2
Wokingham UK
Because the metal they are made of is magnetized....

But a compass needle will react to any metal, not just magnetised ones. The army have a list of distances that you should be away from different objects to ensure your compass is giving a true reading.

Sent from my Moto G (4) using Tapatalk
 

Herbalist1

Settler
Jun 24, 2011
586
0
North Yorks
Yup, any ferrous metal entering the magnetic field of the compass will deflect the needle to a greater or lesser degree. The good thing is that the magnetic field of a compass is pretty weak and therefore limited in area. Therefore just holding your compass in front of you to take a bearing should mean that it's clear of metal gear in your rucksack or on your belt.

A metal item does not need to be magnetised to deflect the compass needle - any piece of ferrous metal will attract a magnet (and vice versa) which is basically all a compass needle is.
 

dean4442

Full Member
Nov 11, 2004
536
2
Wokingham UK
Found this bit from a USMC map reading lesson, don't know how many of these items you'll come across while bushcrafting but it illustrates the point.

:)b.
[FONT=Times New Roman,Times New Roman][FONT=Times New Roman,Times New Roman]Compass Handling[/FONT][/FONT][FONT=Times New Roman,Times New Roman][FONT=Times New Roman,Times New Roman]. [/FONT][/FONT]
[FONT=Times New Roman,Times New Roman][FONT=Times New Roman,Times New Roman][/FONT][/FONT][FONT=Times New Roman,Times New Roman][FONT=Times New Roman,Times New Roman][/FONT][/FONT](1) Handle the compass with care. The dial is set at a delicate balance, which could be damaged by a shock.
(2) Close and return the compass to its pouch when not in use. In this way, it is not only protected from possible damage, but is also readily available for use when needed.
(3) Attach a string or a lanyard between the thumb loop and your equipment to prevent loss.
(4) Compass readings should never be taken near visible masses of iron or electrical circuits. The following are suggested as approximate, safe distances to insure the proper functioning of the compass:
(a) Metal helmet or rifle - 0.5 meters
(b) Machine gun - 2 meters
TACT 3005-3 [FONT=Times New Roman,Times New Roman][FONT=Times New Roman,Times New Roman]TACT 3005-4 [/FONT][/FONT]
[FONT=Times New Roman,Times New Roman][FONT=Times New Roman,Times New Roman][/FONT][/FONT][FONT=Times New Roman,Times New Roman][FONT=Times New Roman,Times New Roman][/FONT][/FONT](c) Telephone wires and barbed wire - 10 meters
(d) Field guns and tank - 18 meters
(e) Power lines - 55 meters
 

santaman2000

M.A.B (Mad About Bushcraft)
Jan 15, 2011
16,712
992
64
Florida
Don't think it's the fact that your knife etc are magnetized, the magnetized needle in thecompass is just reacting to the fact that they're metal.
Colin

BINGO!!!

Because the metal they are made of is magnetized....

Nope. The magnetic needle will be attracted to ALL ferrous metal. The tolls "may" be magnetized, but it really doesn't matter. If you believe those tools are magnetized, test it by trying to pick up a ferrous object with them.
 

Robson Valley

Full Member
Nov 24, 2014
8,706
1,643
McBride, BC
Iron. = Ferrous metals. Non ferrous metals don't magnetize unless you go to enormous trouble with exotic alloy magnets.
Copper and silver coins cannot affect your compass. Not magnetic metals. End of lesson.
Rifle barrels, tent poles. .. yes. aluminum irrigation pipe? No.
 

gonzo_the_great

Forager
Nov 17, 2014
199
44
Poole, Dorset. UK
A compas needle should only be attracted to a magnetised item. And close in, even weakly magnetised items will attract.
But even non-megnetised ferrous metals will distort the local magnetic flux and can swing the compas.

Tape head demagnetisers are not going to work on anything large. They were designed for the ferrous metal inside a tape head. Which is about the size of a small washer.
For things like knives, look out for a Bulk Tape Eraser. The sort of thing used commercially for big reels of magnetic tape, or possibly video cassettes. They may turn up on ebay?

The degausing coils in a TV set were designed to be used little and often, using a thermister as a timing element, to fire it for only a few seconds, on power up. And the shaddow mask in a TV, is a very light foil.

When TV's got badly magnetised, a more serious coil was used. Usually home made by the TV repair man (as no company would ever sell these things!). They were often a 6-9" wooden wheel, with some 13A cable would around the outside and a hole in the centre, to hold it on the end of a broom handle.
One man would wave it over the screen in a few second bursts, till it started to smoke, whilst another would stand on a stool, holding the trips in on the consumer unit.
Quite frightening!