Hamilton 992E pivot size

Discussion in 'Watch Repair' started by BCMC, Jan 13, 2020.

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  1. BCMC

    BCMC Registered User

    Dec 27, 2014
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    Hamilton 992E # 2584923. Is there a way to determine the pivot size needed to order a new staff? Both pivots are broken and am not able to measure. Is there a chart provided by Hamilton according to serial number that states the pivot size that came with the balance? In searching it appears that the correct number is 603 and 11 and 12 are available. Thanks T
     
  2. NC Plumber

    NC Plumber Registered User

    Jan 15, 2011
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    I would say that it came with a 603 staff with 10 pivots. You'll want to measure the jewels to see what size they are before ordering a staff.
     
  3. topspy

    topspy Registered User
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    As I recall there were at least two different staffs used in the 992E, and they were very different! I had one a few years ago that caused me a lot of grief because of this.....
     
  4. Harvey Mintz

    Harvey Mintz Registered User
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    I see that some people have already provided information on the staff type and pivot size, so I'll just address the general problem for determining pivot size - it's really not that difficult, but you'll need some tools.

    The first thing you'll need is an vernier micrometer (metric is best since watch stuff is spec'ed in metric sizes). Then, you need a pin that tapers down from about .20 to .08 mm. If you can't find one, you can easily make one on a lathe.

    Remove the holes jewels from the watch and insert the tapered pin into the jewel. Mark the pin at the point at which it contacts the jewel hole. Remove the pin, and use the micrometer to measure the pin's diameter at the marked contact point. Subtract a small amount to allow for side play; that's your needed pivot size.

    See - I told you it's not that difficult!
     
    Randy Beamer and viclip like this.
  5. Randy Beamer

    Randy Beamer Registered User

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    I agree with Topspy..there are different options. Yours appears to be a double roller, so you'll want to make sure that's one of the criteria as my Hamilton parts book (CA.1951), gives different staff numbers for double vs. single roller configurations. You may have to purchase a few different pivot sizes if you can't easily measure the jewel hole diameters.
     
  6. BCMC

    BCMC Registered User

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    Thanks for the responses. I'll remove the jewel and maybe try to insert a shaved down tooth pick and measure where it stops. T
     
  7. Harvey Mintz

    Harvey Mintz Registered User
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    You'd do better with either a steel or brass tapered pin - the wood of the toothpick can deform when measuring it and give you a false (e.i. small) reading.
     
  8. DeweyC

    DeweyC Registered User
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    I understand the OP is not well equipped. But for future reference:

    A micrometer on a pivot is very risky. The only one I would recommend is the horizontal type with the knife jaws. Feintaster or one made in the schools. Everything else is too clunky and risks damage to a good pivot. Hole jewel would be one size larger.

    The "best" way is with the Seitz set of graduated hole jewels. Pivot size would be one size smaller than the jewel the existing pivot fits.

    Puttin a tapered pin into the hole risks cracking the jewel. very easy to do even for a professional making a pivot to fit.

    While very hard to find, the set of pivot gauges are the way to go. The hole jewel would be one size larger than the pivot that fits.

    Sometime ago someone on this board mentioned a very smart way to make pivot gauges by using broken staffs of known size. You can mount the staff in a toothpick and label it. All you really need are 10/100 to 15/100. I use one as my oil inserter when oiling cap jewels.

    Wish I could remember who suggested this, but THANK YOU! And brilliant.
     
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