Remagnitzing and repolarizing compasses ?

[Peakbagr]

I'm moving stuff from my summer packs to the winter one. 2 of my compasses(Silva Rangers) work fine but a 30 year old Silva I use as a backup has reversed its polarity.
I've read differing advice on the internet re remagnitizing compasses or reversing polarity.

Is there a good method someone can recommend to remagnitize/polarize and do the fixes work and maintain?
For compasses that point properly but swing into place slowly, does remagnizing work and how powerful a magnet is needed for above process?

Thought some folks around here may have had the same problem and the knowledge how to fix.

Thanks,
Alan

 

[sardog1]

What's the rush? Just hang on to it and wait for the flip.

EDIT: You probably know this -- Silva will fix it for you at no charge. "From the U.S.A, call 1-800-572-8822 between 8 am-6 pm, eastern time. From Canada, call 1-800-263-6390." Silva FAQ's

 

[DougPaul]

I'm moving stuff from my summer packs to the winter one. 2 of my compasses(Silva Rangers) work fine but a 30 year old Silva I use as a backup has reversed its polarity.
I've read differing advice on the internet re remagnitizing compasses or reversing polarity.

Is there a good method someone can recommend to remagnitize/polarize and do the fixes work and maintain?

Just did a quick search... It looks like you will need to remove the needle from the compass (so you can touch it to the reforming magnet) to get the best results. If you have to open the compass up (the fluid damped ones use a special oil damper) it will be difficult to reassemble properly, so you might as well just replace it. Of course, you could just use it backwards or give it to an enemy...

One risk of remagnitizing is that you may not be able to do as good a job as the original manufacturer leaving the compass prone to a repeat.

You can certainly try without opening the compass up, but I'd be prepared to replace it. Fortunately, hiking compasses are not too expensive to replace. (In contrast to nautical or aeronautical compasses...)

For compasses that point properly but swing into place slowly, does remagnizing work and how powerful a magnet is needed for above process?

This could also be due to excessive damping (eg the damping fluid is too viscous). If so, you probably need to replace the compass. Offhand, I don't know if one can distinguish between weak needle magnetization and excessive fluid viscosity with home tools and without damaging the compass.


Have you been riding a subway with your compass? I've read of the magnetic fields from (600V DC) subway electric motors damaging compasses.

FWIW, it is generally a good idea to keep compasses away from strong magnetic fields... (DC fields can reverse the magnetization and AC fields can demagnetize.)

Doug

 

[KRobi]

Didn't check out the internet info, but, magnets can usually be "remagnitized" using a strong magnet. I periodically remagnitize student magnets with a powerful AlNiCo magnet. Some of the new Neodymium magnets are fairly easy to find and are strong! Basically you are realigning the domains so they are mostly going in the same direction. That being said, if it has lost its alignment it only takes a slight to moderate bang of the compass to mess it up again. As previously said, storing near other magnets can also weaken alignment. Might want to carry a backup of the backup just in case.

 

[DougPaul]

Might want to carry a backup of the backup just in case.

If they disagree:
* with 2, you don't know which to believe
* with 3 or more, you follow the majority vote...

A number of critical systems (eg aircraft flight control computers) are triple or more redundant.

Doug

 

[Peakbagr]

Fortunately, the 2 more expensive ones, Silva Rangers, are fine. My original Ranger is 30+ years old and the young 'un is about 3 years old.
The one that needs work(25 years old) is air dampened.
Maybe time to send back to Silva and find which pack #4 is stashed.

Thanks - Alan

 

[Peakbagr]

Called Johnson Outdoors. Unfortunately they no longer make the
'made like a tank' model like I'm returning but will send like, kind and quality.
Unfortunately that means plastic instead of the metal bezel. But their customer service was excellent. Friendly, helpful and returned to me in about a week.

 

[DougPaul]

The one that needs work(25 years old) is air dampened.

Sounds like it is actually electromagnetically damped. The moving needle generates a current in the case which produces a force countering the motion thus draining energy from the moving needle.

Doug

 

[Peakbagr]

Thanks, sent you a green colored 'thank you'.

 

[sardog1]

Called Johnson Outdoors. Unfortunately they no longer make the
'made like a tank' model like I'm returning but will send like, kind and quality.
Unfortunately that means plastic instead of the metal bezel.

Sorry to hear that. I'll have to start treating mine with more respect. (Well, I did spring for the nice leather case a couple decades ago -- shouldn't that be enough?)

Off to "the auction site" now to see if there's money to be made speculating in pre-Johnson Rangers . . .

 

[max]

Perhaps the compass got too close to the flux capacitor...eleven million jigawatts can do a lot of damage!

 

[paul ron]

They only reverse after you got hit by lightning.

Perhaps you should just hang onto the old metal compass as an antique?

They don't make em like that anymore!

 

[Peakbagr]

I thought about hanging onto it as a souvenir, but I have the older, army surplus compass my spouse got me for a wedding gift for that.