Rusty hairspring "rejuvination"....a success but at your own risk....

Discussion in 'Watch Repair' started by Whereisitat, Sep 5, 2017.

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  1. Whereisitat

    Whereisitat Registered User

    Mar 14, 2017
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    Howdy...

    I don't suggest this as a tried & true method but I had a really good save so I thought I'd share.

    19j South bend-thin movement-had a failed hairspring stud-I was unable to get the pin out to repair that one. Ok parts watch. Sadly the hairspring was very slightly rusted. At the main bend for the overcoil & along one side very light. This kills the harmonics & the amplitude was poor at best (150 ish) & not reliable.

    I metal detect as a hobby & I have used various rust removal methods to restore coins & other dug & crusty items. Not having much to loose-experiment!.

    Hydrogen peroxide-normal OTC for cuts & things is a great tool. In a small pan heat it slowly on the stove & the rust will start to bubble away.

    You want very low heat & a pair of magnifier glasses to check the progress. I did mine for about 30 seconds at 1st & another 15 seconds. Then I dunk it in water to kill the reaction.

    The hairspring will have lost any blue coating in the process & is now very susceptible to rust. Like in minutes. So I dunked it in a bath of oil & cleaned. This seemed to work ok but I wanted to leave something of a coating to protect it without having any residue.

    I found a soak in Rem-oil & a quick dip in lighter fluid did the trick. You may have other concoctions available but this worked for me.

    Amplitude is over 300 in all positions now and I was able to get nice steady traces on my timer.

    In that I'm stubborn-cheap-and almost always over my watch allowance- so I do these things. Hopefully this one works for a HTF hairspring that needs help.
     
  2. karlmansson

    karlmansson Registered User

    Apr 20, 2013
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    Interesting procedure!

    Over 300 in all positions sounds like it would be prone to overbanking. How much over 300 in the horizontal pos.?
     
  3. Whereisitat

    Whereisitat Registered User

    Mar 14, 2017
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    #3 Whereisitat, Sep 6, 2017
    Last edited: Sep 6, 2017
    So far no problems-but the amplitude is 340 in vertical positions. Dial down is a tad faster 349 & dial up-known issue with cock bearing-is 302.

    Seeing I was struggling to get to 200 dial down before it is a major improvement.

    So-close to the edge-and it has gotten faster since I did the repair. Carried it all day yesterday no issues so I hope it doesn't overbank going that fast.
    But as far as the hairspring-yeah it worked.

    Cheers!
     
  4. Whereisitat

    Whereisitat Registered User

    Mar 14, 2017
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    Small ooops...

    I forgot I had just done my morning "wind". I tested about 1/2 hour after full winding.

    Now-about 2 hours-it is back where I was. Vertical (pu) is 312 face down is 332. Still high but less concerning.

    Glad I double checked.
    And-more coffee more better.
     
  5. karlmansson

    karlmansson Registered User

    Apr 20, 2013
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    Overbanking starts to become an issue at around 320 deg. At 349 it should be overbanking. If you're sure it isn't and your timegrapher is telling you 349, I would check the lift angle using the dot test on the balance rim. Adjust your timegrapher to match the actual amplitude.
     
  6. Whereisitat

    Whereisitat Registered User

    Mar 14, 2017
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    I'm very sure you are correct.

    I'm self taught & just use the timing machine as a comparator. I have rarely varied the factory settings.

    So lift angle is whatever the machine says it was.

    Traces are steady & I have seen knocking before. She's doing fine. Just wanted to share about some rust removal. I didn't think it would work but I'm going to have to say in this case it did.
     
  7. gmorse

    gmorse Registered User
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    Jan 7, 2011
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    Hi Whereisitat,

    That's just the point, the machine can't measure the lift angle, it has to be told. The lift angle is used by the machine to calculate the amplitude, which is why Karl suggested the test to establish what the real angle is so that the amplitude reading is accurate. It's probably set by default to 52° or thereabouts, but watches do vary quite a bit.

    Regards,

    Graham
     
  8. karlmansson

    karlmansson Registered User

    Apr 20, 2013
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    Thanks for sharing the procedure with the rust removal!

    The amplitude caught my Eye, that's all. For establishing the lift angle you paint a dot on the balance rim with something clearly visible, White marker works well generally. Then you start Winding the Watch from unwound. The dot will start appearing as two dots as the balance Changes directions. Keeo Winding until the dot appears as a single dot. That means that the balance is changing direction 180 deg from the impulse in either direction. Check what your timegrapher is telling you and adjust the lift angle up or down until the amplitude Reading corresponds to 180. Just beware that most timegraphers have a sample period of over 10 seconds, so if you've wound the Watch rapidly enough that the amplitude overshoots 180 without you noticing it, the Reading on the timegrapher will be 10s "too late".

    Best of luck!
     
  9. Whereisitat

    Whereisitat Registered User

    Mar 14, 2017
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    Thanks!

    That is the simplest method I've heard of & actually makes sense. The one thing I do adjust regularly is the time span or sample period on the timegrapher. I have found this gets me better readings on watches that are weak or have a hiccup of some kind. Those I do a lot as a bay bottom feeder.

    I will have to use that on my carry watches or when I need a precise answer. For the most part its a better / worse comparison tool. For the last few seconds a day accuracy I almost always do the final tweak by eye & tested response over time.

    Thanks again for the very straightforward method.
     
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