Elgin Hairspring Strength

Discussion in 'Watch Repair' started by James Wrobel, Apr 10, 2020.

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  1. James Wrobel

    James Wrobel Registered User
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    Jan 17, 2020
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    I have two Elgin hairsprings, one is "Strength 2", and the other is "Strength 3". Which one is the stiffer spring?

    Thanks,

    jjw
     
  2. NC Plumber

    NC Plumber Registered User

    Jan 15, 2011
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  3. Chris Radek

    Chris Radek Registered User
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    Apr 13, 2014
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    To judge hairspring strengths, hold the outer end in your tweezers (like it was attached to a cock) and pick up the balance with the other end. It might help to stick it to the balance staff with a blob of rodico or similar. You will see a difference in how far the balance hangs down, and if you have serviced a lot of watches and seen a lot of correctly paired balances hanging from their hairsprings, you can immediately see which hairspring is about right to try.

    You can then do a quick test of the frequency this way - get the center of the spring stuck to the staff, set the other pivot on the crystal of a running watch (I think it helps if it has a loud tick), and give it a poke, and you can see if the frequency is anywhere close to right. If it's too fast just move on - if it's too slow try to find a spot that's about right by holding different spots with your tweezers. If the correct spot is pretty close to the outer end, and the diameter there makes sense for the cock you have, you've got a match.
     
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  4. James Wrobel

    James Wrobel Registered User
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    Thanks, Chris. I suppose any mass hung from the collet would work for the strength test, as long as the mass was identical for both.

    For the second experiment, I have a video stopwatch which will hopefully at least get me the right spring.

    Messing around with hairsprings is way too difficult of a task for a beginner like me, but I have no choice. The watch will either run or it won't. I'm calling this my training watch.
     
  5. Chris Radek

    Chris Radek Registered User
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    It's true you could use anything to strictly answer only the question you asked, but the more interesting question is which spring is right for the balance in your watch? That's why you use the balance, because the reason you have different strengths of hairspring is that balances have different weights.
     
  6. Smudgy

    Smudgy Registered User

    May 20, 2003
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    When comparing the balance vibrations you want to be sure to use a watch with the same vibration as you want the balance to have. If you use a 14400 beat watch to compare a 18000 beat balance you will get the wrong hairspring.
     
  7. gmorse

    gmorse Registered User
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    Hi Smudgy,

    If you just use the comparing watch as a time source, and count the number of oscillations of the balance under test in a set time, say 30 seconds or a minute, it doesn't matter what the beat rate is. Another way to do this, without another watch to compare against, is to set up a click track in something like Audacity. If you make the frequency just half the target, you only have to count every other 'tick' of the test balance.

    Regards,

    Graham
     
  8. Smudgy

    Smudgy Registered User

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    I guess that's true. I've always just used a balance with the same beat and held the loose balance over the watches balance to compare (resting the lower pivot on the upper cap jewel). It's easy and doesn't require any counting, just seeing if they change direction at the same time (or faster or slower when looking for a pinning point).
     
  9. John Runciman

    John Runciman Registered User
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    Aug 13, 2003
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    I don't suppose you have a model number for the watch? From the Elgin 1915 the parts catalog I've snipped out a section that you might find interesting. So the number one hairspring is the heaviest and as the numbers go up the strength gets weaker if I'm interpreting correctly. I've highlighted the relevant section.

    Elgin hairspring strengths.JPG
     
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