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Anyone know how to re-magnetize a compass needle ?

#1 User is offline   tyro-n-www 

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  Posted 09 October 2010 - 07:22 AM

OOPS! ;) While having a senior moment, I placed a magnetic key holder in the same pants pocket where my compass resided. Now I have a compass that the north point, always points south and the south point always north. Although I can still use it ( the accuracy seems to be unaffected ) I now have to remember the reversed polarity of the needle whenever I use it in the field and I would like to get it back to the correct polarity. I know there is a procedure for correcting the polarity in such a case that involves placing the compass in the proximity of a strong permanent magnet but am unsure of just what it involves. Anybody out there ever had a similar experience and successfully "fixed" their compass using another magnet?

#2 User is offline   LethanderMorninglory 

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Posted 09 October 2010 - 12:35 PM

I'm not entirely sure myself, but o ne thought would be what would happen if you degaussed (sp?) the needle itself since its picked up an additional charge.. I would think that the charge on the south needle would have to be removed before it could function? Just throwing a dart at the broadside of a barn here ;)

#3 User is offline   kunarion 

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Posted 09 October 2010 - 02:32 PM

 tyro-n-www, on Oct 9 2010, 11:22 AM, said:

Anybody out there ever had a similar experience and successfully "fixed" their compass using another magnet?
I had a big old monster horseshoe magnet, and could instantly magnetize a tiny one -- to either polarity -- by just pressing the two together. But they'd resist the force at first. Because of the lines of force, I would have thought it would not be possible to switch polarities of a compass needle. But I'm guessing that your needle can jam in certain unlevel conditions, and then another magnet could affect it.

So here's what you might try: Hold the compass at an angle where the needle isn't free-floating, and press that magnetic key holder against the compass case (assuming the needle's sealed inside), as close to the needle as possible, then lift it away from the compass. If it still points wrong, try the same thing with the magnetic key holder at another angle.

The polarity of the keyholder may be tricky. You may first need to find North-South by holding it near the compass, watching the needle follow, and then turning the keyholder 180-degrees from that position to remagnetize while the needle is jammed. The idea is to find the spot with the most powerful reaction, and then force it to the opposite polarity.

EDIT: I just now remagnetized one of my tiny sig-item compasses instantly, using a rare-earth magnet, while holding the compass on its side (so the needle can't move). Now it points South. And I'm gonna sign it and place it in a cache that way. ;)

This post has been edited by kunarion: 09 October 2010 - 06:03 PM


#4 User is offline   tyro-n-www 

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  Posted 16 October 2010 - 07:15 PM

B) I tried what you suggested and it worked fine. Took me about 3 or 4 swipes of the magnet along the axis of the compass needle while holding the compass on its' edge. I later compared the compass needle orientation alongside another similar compass and they both point exactly the same way now. I used the re-magnetized compass in the field on Thursday and today while bushwacking to a cache and it seems to be working perfectly. Thanks for your suggestion

#5 User is offline   kunarion 

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Posted 16 October 2010 - 07:58 PM

 tyro-n-www, on Oct 16 2010, 11:15 PM, said:

:D I tried what you suggested and it worked fine.
Hey, that's great! That was a very interesting problem to consider. B)

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