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Thread: 1st timer re-assembly question (Pallet fork, Balance wheel)

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  1. #1
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    1st timer re-assembly question (Pallet fork, Balance wheel)

    Hello all,

    I have taken the plunge into learning about mechanical movements by completely dissassmbling the movement on a Seiko 7002 dive watch. Re-assembly has been good so far, however I'm now stuck.
    After re-installing the pallet fork i cannot get the balance wheel jewel (sorry, I know there is a term for that) into the end of the fork. If I attempt to install it sometimes the pallet fork will release the escape wheel and the mainspring will spin all the parts.
    My thoughts right now are:
    1. I do not have the escape wheel installed correctly and it is not engaging with the other gears.
    2. I do not have the pallet fork installed correctly.
    3. I am just plain unable to get the balance wheel jewel into the end of the pallet fork and get the watch to run.

    Once or twice i have been able to install the balance wheel and screw down the cock and start the watch only to have it stop running after a few rotations of the balance wheel. During these attpemts I have witnessed the escape wheel rotating and the pallet fork moving.

    Any help would be much appreciated.

    Thank you!

  2. #2
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    Re: 1st timer re-assembly question (Pallet fork, Balance wheel)

    Quote Originally Posted by joshhill View Post
    Hello all,

    I have taken the plunge into learning about mechanical movements by completely dissassmbling the movement on a Seiko 7002 dive watch. Re-assembly has been good so far, however I'm now stuck.
    After re-installing the pallet fork i cannot get the balance wheel jewel (sorry, I know there is a term for that) into the end of the fork. If I attempt to install it sometimes the pallet fork will release the escape wheel and the mainspring will spin all the parts.
    My thoughts right now are:
    1. I do not have the escape wheel installed correctly and it is not engaging with the other gears.
    2. I do not have the pallet fork installed correctly.
    3. I am just plain unable to get the balance wheel jewel into the end of the pallet fork and get the watch to run.

    Once or twice i have been able to install the balance wheel and screw down the cock and start the watch only to have it stop running after a few rotations of the balance wheel. During these attpemts I have witnessed the escape wheel rotating and the pallet fork moving.

    Any help would be much appreciated.

    Thank you!
    I'll try to give you what little benefit can be extracted from my very limited experience:

    1. Whether the balance is installed or not, the pallet stone should lock the escape wheel, and if the pallet is prodded (gently!!!) to the other banking pin, the escape wheel should be locked by the other stone.

    If the escape wheel spins, the pallet is not properly installed. Personally, I find them to be the hardest part of putting a watch back together - i fiddle and fiddle and fiddle, and then finally the pivot gets into the hole of the jewel and the bridge drops into place. But it always takes me a while, and sometimes screwing down the bridge gets it

    2. With the pallet not installed, does prodding the center wheel set the whole train spinning? Can you see the pivots of each wheel in the center of the jewel on both sides? Then they're installed correctly.

    3. I don't bother trying to get the roller jewel into the pallet fork. If you get the balance pivots into their jewels properly, it will engage the pallet correctly. Usually the watch will start running once the pivots are in place, before you even have a chance to screw down the balance. Indeed, if it won't run, I don't screw it down at all, but rather I work with it until it does. Sometimes this means removing and reinserting the balance, sometimes just gently moving the balance, making sure it's vertical and not tipped in any direction.

    BTW, if you've screwed pallet bridge down all the way with the pivots not properly seated, you might have bent or snapped off one of the pivots. Inspect it carefully before reinstalling.

  3. #3
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    Re: 1st timer re-assembly question (Pallet fork, Balance wheel)

    Quote Originally Posted by GeneJockey View Post
    I'll try to give you what little benefit can be extracted from my very limited experience:


    BTW, if you've screwed pallet bridge down all the way with the pivots not properly seated, you might have bent or snapped off one of the pivots. Inspect it carefully before reinstalling.
    Ahh Jeez, it looks like this might be the case. I' musre learning as I go. Does anyone know where I can get a new pallet fork for this movement? Am I better off just buying a new movement off ebay?

    Thanks

  4. #4
    JAA
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    Re: 1st timer re-assembly question (Pallet fork, Balance wheel)

    I had the same issue with a watch that's on my bench now. I my case, the cause was the hairspring having fallen out of the regulator pins.

    A broken escape wheel pivot taught me to be gentle when installing watch components.

    Movement identification and parts search is another opportunity for learning. I've had good experience getting partial movements from dashto.com. Sometimes, the part you need would come from a non-identical sister movement.

    Don't give up! You'll get it. If it's that easy then everyone could be a watchmaker :)
    Last edited by JAA; January 24th, 2012 at 04:39.

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    Re: 1st timer re-assembly question (Pallet fork, Balance wheel)

    Quote Originally Posted by JAA View Post

    A broken escape wheel pivot taught me to be gentle when installing watch components.
    Mine was driving a 3rd wheel pivot through a jewel by screwing down the train bridge when the pivots weren't all lined up. *CRUNCH*

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    Re: 1st timer re-assembly question (Pallet fork, Balance wheel)

    I think i might buy a trashed 7002 of ebay. The bezel on mine is messed up anyway (spingball mech is totaly gone). So two birds with one stone.

    It was stangely gratifying to find out I had a broken part. It was hours of not knowing what was wrong followed by that "ahh ha" moment.

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    Re: 1st timer re-assembly question (Pallet fork, Balance wheel)

    There's nothing wrong with the pallet fork in position, complete with the escape wheel. However before you put the balance spring in place , there's a jewel near the spindle of the bal. spring which has to be positioned in between the fork so that the spring can give the watch the impulse needed to keep it going. Try it with care when putting the balance spring in . ps. If the jewel is outside the fork, the balance would be locked -- thereby stopping the watch. The term is " overbanking "

  8. #8
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    Re: 1st timer re-assembly question (Pallet fork, Balance wheel)

    You don't need to "position" the impulse pin. Once the pallet is in place, you should wind the mainspring a couple of clicks. This should bank the pallet to one side or the other. At this point, you should gently prod the pallet a few times to ensure that it "snaps" back and forth smartly. If it doesn't, stop and fix that. Once that's working, you just have to put the balance so that the impulse jewel is rotated to the same side that the pallet is banked to. Don't let it go until you have the staff seated, but before you tighten the screw on the balance cock. The balance wheel should rotate back and forth (probably a bit jerkily). Gently hold down the balance cock and tighten the screw.
    My growing collection of "affordable" vintages: http://www.abslomrob.com

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    Re: 1st timer re-assembly question (Pallet fork, Balance wheel)

    Quote Originally Posted by AbslomRob View Post
    You don't need to "position" the impulse pin. Once the pallet is in place, you should wind the mainspring a couple of clicks. This should bank the pallet to one side or the other. At this point, you should gently prod the pallet a few times to ensure that it "snaps" back and forth smartly. If it doesn't, stop and fix that. Once that's working, you just have to put the balance so that the impulse jewel is rotated to the same side that the pallet is banked to. Don't let it go until you have the staff seated, but before you tighten the screw on the balance cock. The balance wheel should rotate back and forth (probably a bit jerkily). Gently hold down the balance cock and tighten the screw.
    Failing to place the impulse jewel in between the fork, the balance will bank & lock-wheel would follow no matter how many times the balance wheel turns.

  10. #10
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    Re: 1st timer re-assembly question (Pallet fork, Balance wheel)

    I'm not sure if I fully understand what you're saying, but I suspect your approach assumes the mainspring is completely let down. This should leave the pallet fork centered (and if it isn't, there's possibly something wrong). In this scenario, yes you'd have to ensure that the impulse pin put into the fork during assembly or the watch won't run.

    I'm just not sure why you'd do it that way (and would love to understand the reasoning). The approach I outlined seems "easier" because you don't have to worry about it as long as the pin is rotated to the same side that the fork is banked to. As long as the staff is seated properly, the pin will go into the fork naturally.

    There's some value to verifying that "at rest" the balance and fork are centered, as a method of ensuring that watch is in beat. I accomplish this earlier by assembling the balance on the pillar plate with nothing else on it, and checking that the impulse pin is centered on a the line between the staff and pallet arbor.
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