Adjusted & Chronometer Watches. How are they made?
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Thread: Adjusted & Chronometer Watches. How are they made?

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  1. #1
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    Adjusted & Chronometer Watches. How are they made?

    I've come across several watches w/ "Chronometre" "3 Pos" "5 ADJ" "5 Pos" ""ADJ to two(2) Pos" on the movement or just "Chronometer" on the dial. I've always like these watches in particular and assumed that the build quality of these watches were superior to those that were "Unadjusted". They wouldn't waste man hours adjusting a low quality watch, right? I also heard somewhere that manufacturers used only the best parts and their most talented watchmakers to build these watches. Is that right? Maybe someone here has an idea of how these watches were made and if there is a difference in build quality. For example, Longines makes a movement called Cal. 25.17. Some of these movements have the "5 ADJ" and some do not. My guess is that the best parts were put into the adjusted versions. Another funny way to look at it would be that the parts were so bad they required adjusting

    I purchased a book call "Wristwatch Chronometers" by Fritz Von Osterhausen so hopefully that could shed light to this and I'll be posting any information I gather here.

  2. #2
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    Re: Adjusted & Chronometer Watches. How are they made?

    The word Chronometer or Chronometre used on a dial does not always mean that what you have inside is a Chronometer grade movement. You hear the phrase chronometer balance in the Waltham ledgers in the 1800's. This was not indicating that the watch was a chronometer but rather the balance was a split bimetallic with timing screws of a better design that the expansion, gold, or steel balances they used.

    When you do a search on the bay and put in "Chronometre" you will find watches of obviously lower quality that would never pass chronometer testing. But that is also because they were not referring to it as an actual chronometer as it never went through testing but as just a word to mean that it was a good time keeper. So just because it says Chronometer on the dial or on the inside of a case on a pocket watch....does not mean it was submitted for chronometer testing.

    As to materials and having the highest skilled workers work on them....have a look at the giant machine of a movement maker ETA. The same movement cal can be multiple grades all the way up to chronometer. The designs are the same. Some slight changes may be made to the balance and hairspring and it may be adjusted more by hand. Then it is submitted to testing. There is usually extra care and attention spent on adjusting and making sure that the performance is tuned. Like tuning an engine.

    As to adjustments that is usually referring to positions, temp and isochronism. Temp is usually done with using types of balances and materials. Positions is usually done by adjusting the screws on a balance but on other balances it is by other methods than screws. Adjusting to position eliminates or minimizes errors in various positions of a watch. Face up, face down, stem up, stem left, stem right, and stem down are the positions.
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    Re: Adjusted & Chronometer Watches. How are they made?

    Quote Originally Posted by bikerjl123 View Post
    I've come across several watches w/ "Chronometre" "3 Pos" "5 ADJ" "5 Pos" ""ADJ to two(2) Pos" on the movement or just "Chronometer" on the dial. I've always like these watches in particular and assumed that the build quality of these watches were superior to those that were "Unadjusted". They wouldn't waste man hours adjusting a low quality watch, right? I also heard somewhere that manufacturers used only the best parts and their most talented watchmakers to build these watches. Is that right? Maybe someone here has an idea of how these watches were made and if there is a difference in build quality. For example, Longines makes a movement called Cal. 25.17. Some of these movements have the "5 ADJ" and some do not. My guess is that the best parts were put into the adjusted versions. Another funny way to look at it would be that the parts were so bad they required adjusting

    I purchased a book call "Wristwatch Chronometers" by Fritz Von Osterhausen so hopefully that could shed light to this and I'll be posting any information I gather here.
    First thing to know is that watches and movements imported into the US back in the 50s and 60s were often labeled "unadjusted" whether they were adjusted or not, because there was a substantial tariff on adjusted movements.

    Second thing is that, for example, in putting a balance together, the 'fixed' parts - balance wheel, staff, and roller - may be statically poised such that the mass is perfectly balanced, but then you add the hairspring. The hairspring, of course, is fixed to the balance cock at one end and the collet at the other, so that as the balance oscillates and the hairspring winds up and winds down, its moment of inertia changes. Also, the collet itself adds considerable mass and it's got a big slot cut into it. So, even if the balance is in perfect STATIC poise, it must also be poised dynamically, which involves adjusting mass balance such that the balance runs at the same rate - within a handful of seconds a day - in as many positions as it's spec'ed for. Before timing machines, this meant timing for a whole day in each position, determining where mass needed to be adjusted (added, subtracted, or moved), doing that, and then testing AGAIN. With timing machines, you don't have to wait a whole day, but it's still a painstaking, iterative process.

    A watchmaker who posts on the NAWCC board recently put considerable effort into describing the process of adjusting for position. It's way beyond what a hobbyist like me would do, but it's very interesting to know how it's done.
    Last edited by GeneJockey; July 25th, 2019 at 01:47.
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