Elgin A-8 Bomb timer

Discussion in 'American Pocket Watches' started by Spartcom5, Apr 13, 2017.

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  1. Spartcom5

    Spartcom5 Registered User

    Feb 1, 2016
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    Picked this up for a measly $15! Didn't even know what it was until I got home. Seems to be a stopwatch Elgin from WW2. Great condition except for the fact the crystal fell out and the hand is missing. I can imagine finding a replacement hand is quite hard... It runs but it doesn't seem to stop when I push down on the crown. Cool display piece for $15! Maybe I'll get it fixed up one day, any idea on a hand?
    [​IMG][​IMG][​IMG]
     
  2. GeneJockey

    GeneJockey Registered User
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    It's an Elgin grade 582 'Jitterbug' timer. Made in 1943, in this case.

    It's not really a stopwatch in the standard sense. It runs as long as there's power in the mainspring. It uses what are essentially chronograph works to connect the hands to the train. It should be running at 30 bps, so that the hand, if it were there, would go around in 10 seconds, and the minute register hand ticks over one step every 10 seconds, allowing you to time up to 5 minutes.

    They were also made with larger balance wheels, to run at 5 bps, so you could make a 1 minute timer with a register thatgoes up to 30 minutes.

    I did a post about the Jitterbug, on my blog. The chronograph works are very similar to those on the Hamilton Model 23 Chronograph, but of course that also has a time function.
     
  3. Bila

    Bila Registered User
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    Jan 22, 2010
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    A nice jitterbug timer, looks like the sweep centre pinion is partly missing, that will be a little harder to find then the hand.
     
  4. topspin

    topspin Registered User

    Dec 14, 2014
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    It's ironic that this is a bomb timer... in the first photo, if you squint a bit, it actually looks like a bomb, possibly falling through the air. With the bow representing the bomb's "tail". Can anyone else "see" that?
     
  5. River rat

    River rat Registered User
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    #5 River rat, Apr 13, 2017
    Last edited: Apr 13, 2017
    Nice pick up. Here is one with out the jitterbug balance wheel I picked up close to the price you paid 20 bucks at the Alameda antique fair years ago it did not run but a few drops of oil does wonders she now runs. A Hamilton 4992B sweep hand would be easy to find and mite work for your missing hand looks close to what I have on mine. If you get the NAWCC bulletin the paper booklet mart highlight there a seller who sells Hamilton military parts that mite have a Hamilton 4492B sweep hand that just mite work for your missing hand.
    [​IMG]

    [​IMG]

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    Different issue marks on mine that I have not seen on any other. Notice how they oxidized the most important parts of the movement that's the black coating to prevent rust due to were it was used in combat were weather conditions could cause rust.
     
  6. Tom McIntyre

    Tom McIntyre Technical Admin
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    If I am not mistaken these are two different products. The OP watch has its very small balance and beats at a very high rate, hence the name jitterbug. River Rat's watch is also a timer, but with a normal balance and 60 minute operation for long duration events.

    The English firm Frodsham's sold a similar instrument which used a high speed cylinder escapement that was made for them by Nicole Nielsen. It was used by the British navy as a "Time of flight" instrument. I believe it was meant to measure the time from the flash to the sound of a ship's guns to estimate the distance, or the time from the sound to the splash of the ordnance to adjust range.

    I think the French Auricoste timers that the U.S. Navy purchased around 1900 were used in the same way.
     
  7. Candew

    Candew Registered User

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    It is actually a ground navigation timer not a bomb timer. When flying over the ground you would start the timer at a known landmark then stop it at another some distance away. You can determine your ground speed that way.

    I have two A-8's. One was my father in laws who was an aircraft navigator and retired as a ltcol from the Air Force. His was an Elgin. The other I have is a Waltham. He used it for 20 years and the engraving is all but word off.

    Once wound up the they start running and will run till they mainspring unwinds.. You push the crown to start the timer then push it again to stop. One more push resets it.
     

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  8. Spartcom5

    Spartcom5 Registered User

    Feb 1, 2016
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    Thanks everyone!! My watch does run but it doesn't seem the smaller hand ticks.... However, doesn't it only move every one minute the sweeping hand is moving? If so no way for me to tell since there is no hand! There's gotta be a replacement part for this out there somewhere! But yes, my watch does run, the ticking is crazy fast which is very cool. Would a glass crystal have been original?
     
  9. grtnev

    grtnev Registered User
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    #9 grtnev, Apr 15, 2017
    Last edited: Apr 15, 2017
    I have four of these timers, two made by Elgin and two made by Waltham.

    The Elgin variant features a movement that is always running, even when the sweep second hand is stopped, so as to employ a “flying start” for any timing operation.

    The Waltham variant movement stops running when the sweep second hand is stopped and restarts when the sweep second hand is started.

    One can argue that that the constant running Elgin is a superior design over the Waltham - especially when timing an event down to 1/100th of a second. Additionally, the Elgin is a 15 jewel movement where the Waltham is a 9 jewel movement.

    Some of the Elgin movements were gold flashed and some weren’t.

    The last attachment (PDF file which for some reason just looks like a black square) contains my notes on the A-8. Double click on the black square to open the PDF file.

    Richard





    [​IMG][​IMG][​IMG][​IMG][​IMG]



     

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  10. Bila

    Bila Registered User
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    Jan 22, 2010
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    To my knowledge these were issued with a plastic crystal.
     
  11. River rat

    River rat Registered User
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    Contact this guy a sweep hand for a 4992B mite work for the missing hand.
    http://www.hamiltonparts.com/
     
  12. River rat

    River rat Registered User
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    See what I mean by close match 4992B sweep hand more easy to get
    [​IMG]
     
  13. Spartcom5

    Spartcom5 Registered User

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    Thanks RiverRat, I found a 4992B replacement online and its a 16S size. That's the same as the A8 right? Just making sure before I drop $15 on a hand!
     
  14. PWfanatik

    PWfanatik Registered User
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    Were the short run timers more officially called Ordinance timers?
     
  15. River rat

    River rat Registered User
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    Not sure but a good watchmaker mite be able to make it fit if it's a little off it's the closes thing you are going to find. You mite email that seller I posted the link to he mite have a cheaper price. One thing about this hobby some parts you have to substitute like hands and take a chance and hope they fit been there before. Hope that helps.
     
  16. NC Plumber

    NC Plumber Registered User

    Jan 15, 2011
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    I just pulled the sweep second hand off a 4992b and the shaft that the hand fits on measures. 0.23 mm.
     
  17. GeneJockey

    GeneJockey Registered User
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    And I just checked one of my Elgin Timer parts movements, and the post measures 0.25mm. I

    'd be very cautious in installing it. Some of the parts movements I have, the only real problem is the post is broken off the sweep seconds pinion. Perhaps pushing the hand onto the post carelessly? But a too-small pipe can also lead you to pushing too hard.

    The thing is, the pipe has to be a tight fit. The flyback is abrupt, and if the hand doesn't fit TIGHTLY, it will slip, and not return accurately to 0:00.
     
  18. kevinstang

    kevinstang Registered User
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    Learned something knew about these Elgin timers today, I have a couple and one in parts box. The running ones I have all had the large balance, checked the one in parts and its the small wheel Jitterbug style- had to look with a loop. I guess I always thought someone had robbed the balance wheel out of it all ready. Its incomplete, missing crown and the large hand in middle ( I used it for one of my others), also sadly the hairspring is twisted and staff bad. If original poster needs the center pinion let me know I think its ok on this one or can check.
     
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