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Weak Pulsar setting magnets...

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cte

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Weak Pulsar setting magnets...

Post29 Aug 2015, 10:28

Hi everybody :D

I have three original Pulsar setting magnets here. One is the metal horseshoe type, the other two are the solid black ones. All of them, particularly the horseshoe one, seem to have lost their magnetic strength. The two black ones are able to set the hour but only rarely are they able to set the mins. The horseshoe one will not set anything. I am testing them on three different P2's.

I did a silly thing, because I am now using SASM modules, I was housing an extra (non original) magnet in the clasp with the original magnet. That way it was easier to get to the extra settings if I need to. Stupid, I know.

Is there any simple way of repolarising the magnets? Thanks everyone :grin1:
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bruce wegmann

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Re: Weak Pulsar setting magnets...

Post30 Aug 2015, 00:28

Theoretically, it is possible to re-polarize these with a rare-earth magnet, but in practice, it is very difficult to get BOTH the strength, polarity, AND field orientation correct. Originally, these were done in what is called a gap-magnet; a type of electromagnet shaped rather like a ring with a small section missing (the "gap"). The part to be magnetized is placed in the gap (in this case, in a very specific orientation), current is applied, and a powerful field is briefly established. Power is then shut off, and the part is now (more or less) permanently magnetized. The Pulsar setting magnets are all sintered AlNiCo V (5), an aluminum-nickel-iron alloy, made by mixing powdered metals, heating them to just under the melting point, and pressing them under tons of pressure into shaped molds. The "D"-shaped (P3) and half-D (P4) magnets were apparently done in individual molds; the "C" type was done as a long bar, and sliced (loaf-of-bread style) into individual magnets...the curved lines left by the cutting saw are clearly visible on both sides (variations with rounded and more squared-off corners exist). Though these were the best "permanent" magnets that could be made at the time, they were still susceptible to loss of field strength by either mechanical shock, or exposure to strong external magnetic fields.
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cte

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Re: Weak Pulsar setting magnets...

Post30 Aug 2015, 22:12

Thanks Bruce. :-D I played about with a stronger household magnet yesterday. Experimenting swiping it across the setting magnets etc. Now the setting magnets can be used as long as they are placed on the rear of the watch at 90 degrees (long ways upward rather than across). And even then, only certain corners of the setting magnet actually work now. I will try with other magnets that I come across. I can't believe I did such a stupid thing lol. :bang: :lol: Thank you again for your your guidance.

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