Do all roller tables have roller jewels?

Thread: Do all roller tables have roller jewels?

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  1. #1
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    Do all roller tables have roller jewels?

    Recent purchase is an Illinois 16s 17 jewel pocket watch.
    Not running and when balance wheel is shaked the second hand isn't moving.
    I pulled reg cock and found only a hole in the balance table.
    I see there is a pin sticking up from the pallet fork.

    What at is this pin for? It looks like it would fit into the hole in the table. Is this possible?
    is there supposed to be a roller jewel in this hole? If the pin has any significance what is it?
    i haven't tried setting in the wheel by aligning the pin in the hole, so I don't know if I'm chasing a fault in my strategy.

    I know that a roller jewel will engage the fork opening of the pallet fork and that the roller jewels detach making no link for the escape wheel thus no running of the hair spring.

    So, do all tables have a jewel or is this hole supposed to mate with the pin of the same diameter as this hole sticking up just behind the fork opening? If I must shellac a jewel onto the table what then is the purpose of the pin on the pallet fork?
    Last edited by Jftman; December 18th, 2013 at 13:53.

  2. #2
    Vintage & NAWCC Forum moderator Ben_hutcherson's Avatar
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    Re: Do all roller tables have roller jewels?

    Yes, all roller tables should have a roller jewel, although this sometimes get replaced with a steel or brass pin.

    The pin that you're seeing is the guard pin, which only allows the pallet fork to move when the roller jewel is in the pallet fork. It sounds like you have a single roller escapement-on these the guard pin sticks straight up perpendicular to the pallet fork.
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  3. #3
    Member AbslomRob's Avatar
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    Re: Do all roller tables have roller jewels?

    The technical term for that condition is "Broken". And the fact that you asked the question means you dont' have the skills, material or ability to fix it yourself.

    The impulse jewel (on cheap watches it's just a metal pin) is supposed to be attached to the balance roller table. It has the job of 1) unlocking the pallet fork from the escape wheel, allowing the escape wheel to turn. This causes the escape wheel to push the pallet stone. 2) the impulse pin gets pushed by the pallet fork, allowing the balance wheel to rotate more.

    IF it's a jewel, the impulse pin is normally attached by shellac. However, if the pin is "stuck" in the fork of the pallet, that suggests that either the impulse pin is too big or the opening in the pallet is too small. The latter is more likely, and could be becuase some hack replaced the pallet fork with the wrong replacement.
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  5. #4
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    Re: Do all roller tables have roller jewels?

    I do follow what u said. Since my table has no pin or jewel but only a hole. Then the jewel is missing. Which would be why the escape wheel isn't being turned. More properly the escape isn't unlocked because the fork to table link is "broken".

    on this watch there is no stuck anything with the fork involved.
    The pin I am not sure of sticks up perpendicular to the pallet fork and is located just behind the center of the fork opening. If this is called a guard pin I don't understand why it exists. This is a longer more slender pin shape than the two bank pins.

    Its pretty clear that it would not go into the hole in the balance table. Although that pin looks the right size. What contacts this pin or what does it contact in the movement of the pallet fork?

    True what u say. This will be my first roller jewel repair. I have the tools but just have some questions. I'm thankful for ur reply.
    regards,
    james

  6. #5
    Member Robocaspar's Avatar
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    Re: Do all roller tables have roller jewels?

    The guard pin doesn't touch anything. It serves as a redundancy that insures the roller jewel is properly inserted when installing the balance bridge.


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  7. #6
    Vint. Forum Co-Moderator Mirius's Avatar
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    Re: Do all roller tables have roller jewels?

    Quote Originally Posted by Jftman View Post
    True what u say. This will be my first roller jewel repair. I have the tools but just have some questions. I'm thankful for ur reply.
    regards,
    james
    James. The fact that you have the tools but do not understand the function of the parts you are dealing with does not bode well. Even the most basic books on watchmaking cover this. I would suggest that you invest some time in learning about this before you go anywhere near the watch with tools as the escapement is one of the areas that requires the most advanced watchmaking skills.


  8. #7
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    Re: Do all roller tables have roller jewels?

    Audemars Piguet escapement - YouTube

    hope this help you
    regards enrico

  9. #8
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    Re: Do all roller tables have roller jewels?

    The lever which has the two horns and guard pin at one end(two pallet stones at the other end) always needs to rest firmly against the one of the banking pins when not in contact with the impulse jewel(the one missing in your watch on the roller) if the watch received a knock and the guard pin wasn't present, the lever would move away from the banking pin which would result in the impulse jewel becoming trapped behind one of the horns,this is called overbanking. So with endshake(clearance),the guard pin stops this from happening by allowing the tip of the guard pin to make brief contact with the edge of the roller,this stops the lever moving away from the banking pin too far. on the roller you may notice a small radius has been taken out of the roller edge that sits behind the impulse jewel, this is known as the passing crescent.the guard pin can only move to the other banking pin when the guard pin sits within this crescent,which is at the very moment the impulse pin makes contact with one of the horns.
    Last edited by eldridge; December 21st, 2013 at 15:29.

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