How easy is it to magnetize an auto movement?
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  1. #1
    Member Ginseng108's Avatar
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    How easy is it to magnetize an auto movement?

    Just wondering what your experiences have been with respect to magnetization of automatic watch movements. I ask because I occasionally use earbuds that click together by embedded rare earth magnets.
    Just what kind of exposure is needed to affect the accuracy of the system?

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    Re: How easy is it to magnetize an auto movement?

    I have magnetized a few of mine. I don't know if it was magnets on my desk (headphones and the such) or going through airports. It is fairly easy...
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    Member Stellite's Avatar
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    Re: How easy is it to magnetize an auto movement?

    Modern movements with non iron based hair spring have a very low chance of magnetization. In general, modern movements have high alloy metals so any magnetism is easily repairable. In the 90's I use to have to work in a magnetic environment around large power plant generators and I never had any issue with magnetics. Out of all the watches I have owned, several hundred, I have only had one that I could even remotely consider to have been magnetized and to me it was just terrible at keeping time, but it may have been magnetized. I never checked as it was cheap and not worth repairing.
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    Member Ginseng108's Avatar
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    Fascinating. I get the feeling that magnetization is a bit of an "is it real or imagined" phenomenon.

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    Re: How easy is it to magnetize an auto movement?

    Quote Originally Posted by TechDiverGeek View Post
    I have magnetized a few of mine. I don't know if it was magnets on my desk (headphones and the such) or going through airports. It is fairly easy...
    I second this. When you track accuracy of your watches you become more aware of magnetism. I was unaware of how easily magnetism can affect a watch until about 10 years ago I bought a planet ocean 2500 used off the forum. It kept time at -1 second per day for a month and then suddenly started gaining 5 seconds per day.

    I bought a demagnetizer off eBay and ran the watch though it. Immediately it was back to -1 spd. Anyone who says a watch is only magnetized if it’s “gaining minutes per day” has no idea what they are taking about. I see this repeated often on this forum.

    Magnetic fields are everywhere. They can vary in strength and there are degrees of magnetism. I have never had any idea how my watches have become magnetized, it just happens.

    I now have adopted a standard procedure of running any used watch I buy off the forums through a demagnetizer on arrival.

    What’s funny is a few months ago I bought a Brand New Seiko SBDC053 from Gnomen. It arrived gaining 12 seconds per day out of the box. After a week I ran it through my demagnetizer just to see what would happen before regulating it, and it started running -3 seconds per day immediately. I can only guess it was magnetized in transit somehow.

    My demagnetizer has become an important tool in my watch box.

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    Member Ginseng108's Avatar
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    Would you please post an example of the type of demagnetizer you use?

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    Re: How easy is it to magnetize an auto movement?

    Also, a cheap REAL compass will tell you if you have a problem. Lay the compass flat then move the watch around it. If the needle moves with the watch you have some degree of magnetization. Check any metal bracelets and buckles too.
    In addition to the magnets on your earbuds they also produce a small magnetic field simply because they're tiny speakers. I don't think your earbuds could affect anything unless maybe you left them on the watch for a long period of time. Larger speakers can cause much larger disturbances in the force. Just be aware that those influences are all around us. And if you are infected, you are easily cured.
    Last edited by slorollin; January 31st, 2020 at 15:46.
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    Member Biginboca's Avatar
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    Re: How easy is it to magnetize an auto movement?

    Quote Originally Posted by Ginseng108 View Post
    Would you please post an example of the type of demagnetizer you use?
    I use this one purchased off eBay a long time ago...



    I’m not sure it matters tho. It looks like there’s a newer style I paid $35 for this one, and I wouldn’t spend more than that. I bet they all do the job.

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    Member Ginseng108's Avatar
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    Thanks! Looks like I'm going to give this a try.

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    Re: How easy is it to magnetize an auto movement?

    Quote Originally Posted by Biginboca View Post
    I second this. When you track accuracy of your watches you become more aware of magnetism. I was unaware of how easily magnetism can affect a watch until about 10 years ago I bought a planet ocean 2500 used off the forum. It kept time at -1 second per day for a month and then suddenly started gaining 5 seconds per day.

    I bought a demagnetizer off eBay and ran the watch though it. Immediately it was back to -1 spd. Anyone who says a watch is only magnetized if it’s “gaining minutes per day” has no idea what they are taking about. I see this repeated often on this forum.

    Magnetic fields are everywhere. They can vary in strength and there are degrees of magnetism. I have never had any idea how my watches have become magnetized, it just happens.

    I now have adopted a standard procedure of running any used watch I buy off the forums through a demagnetizer on arrival.

    What’s funny is a few months ago I bought a Brand New Seiko SBDC053 from Gnomen. It arrived gaining 12 seconds per day out of the box. After a week I ran it through my demagnetizer just to see what would happen before regulating it, and it started running -3 seconds per day immediately. I can only guess it was magnetized in transit somehow.

    My demagnetizer has become an important tool in my watch box.
    From what I've read, I think there's more to it than that.

    A change in the daily rate of 6 seconds per day wouldn't necessarily be caused by magnetism. The change in the daily rate could also be caused by positional variance and isochronism.

    According to Marc in the video below, magnetic effects are cumulative. I take that to mean the longer the exposure to the magnetic source, and/or the more powerful the magnetic field, the more it impacts timekeeping.

    In most cases, a magnetized watch will run very fast, typically tens of seconds, if not minutes per day. The balance spring is sticking to itself, effectively making it shorter, leading to a big gain in speed.

    Hypothetically, maybe it's possible a magnetized watch may be only slightly magnetized, and thus only gain a few seconds per day. But that small a variance in the daily rate may just be normal variance or the effect of isochronism, so most people, even watchmakers, wouldn't see it as a reason to be concerned, or something that needs to be corrected.

    On the other hand, if a watch suddenly picked up a lot of speed, without being dropped or taken a hard knock, the most obvious explanation would be magnetization.

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