American PW Pallet fork travel stops adjusted.

Discussion in 'Watch Repair' started by Ticktinker, Oct 31, 2015.

  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  1. Ticktinker

    Ticktinker Registered User
    NAWCC Member

    Jul 7, 2015
    1,067
    16
    38
    Male
    Construction Inspector
    Houston Texas
    Country Flag:
    Region Flag:
    Hell everyone and thanks for visitingmy post.
    I have a nice Elgin 0S G320 mod2 15036330.
    Going throught this watch I found that the balance wheel seems to find a dead end in its travel in one direction, This could be that the roller and pallet fork are not lined up when the balance is put in place. The roller when observed is in 90 degree to the balance arm. all of the teeth on the escape wheel seem even and complete. the pallets operate on all of them. Moving on I find the hold down for the pallet arm is terribly scratched, the pallet fork its self looks like it could possibly be twisted or in some other manner not as designs would desire...
    I found the bridge that holds the pallet fork top pivot a little mis shapen, but the fork was free when installed in place, and the fork seemed to travel in the correct path, but had some up and down play if touched at the fork.
    When I look on the front face I find the pallet travel stop screw head type adjusting slots are bashed as if someone used a 2 LB ball peen on them, someone really forced these things with their screw driver to make them move.
    So there is my primary concern, is this old girl ok if the fork travels well enough to let the escape do it's business?
    Should I make the clearance close so the fork will not over-travel?
    And what if any would be a rule of thumb for what distance should be between the posts?
    Is there a basic rule like 3 or 4 times the width of the fork arm?
    If I can find a new pallet fork and escape wheel I will get those...
    In the mean time It also needs a mainspring,,, time to reinforce my mainspring skills...
    Thank you all for any input you have and have a great weekend!
     
  2. saskjoe

    saskjoe Registered User

    Dec 1, 2011
    278
    1
    18
    Country Flag:
    Region Flag:
    #2 saskjoe, Oct 31, 2015
    Last edited: Oct 31, 2015
    I'll be watching this post because I have a PW that's been messed with like that. One thing I recall reading, watch the interaction of the escape tooth and pallet. The tooth should stop securely but quite close to the top of the pallet. Then it needs enough room to be 'drawn' down the surface of the tooth. This draw action gives the wheel more impulse. Too much movement, and I'm reasoning the fork opening would be out of ideal position for the return of the roller as well as wasting energy. When people meddle with that setting I suspect they tried to compensate for a sloppy fitted fork or mis-positioned pallet or guard pin, or wrong roller pin or table maybe. This topic gets covered in books with lots of detailed geometric drawings and angles specified--nice but hard to apply to real life at your workbench. And size 0! It's hard enough to observe on a 16.
     
  3. Ticktinker

    Ticktinker Registered User
    NAWCC Member

    Jul 7, 2015
    1,067
    16
    38
    Male
    Construction Inspector
    Houston Texas
    Country Flag:
    Region Flag:
    Well, at least this one has observation ports on the dial side.
    It will be a while until I receive a mainspring and have the power train there to see how the watch works as a whole again.
     
  4. Smudgy

    Smudgy Registered User
    NAWCC Member

    May 20, 2003
    2,816
    10
    38
    Country Flag:
    Region Flag:
    There isn't really a rule of thumb for what your asking if I understand what you are asking. What you need to do starting out is to check where the pallet hits the tooth when released to find out if that is within acceptable range. The tooth should land safely on the locking face of the pallet, without landing too far down (it creates a loss). After you get the pallets landing correctly then the banking pins are adjusted. They are set by closing them to the point where the pallet won't clear the escape wheel teeth, then opened just to the point that they drop the teeth (all of them). Then the pins are opened a little more for safety. So there isn't really a rule for how far out the pins are set because their positions are dependant on the geometry of everything else. If they look like they are excessively open, they very well could be. It is possible they have been set using the normal procedure and appear strangely open because the geometry of the escapement is so far off from where it should be (because of maladjustment or indiscriminate part replacement). Your best course of action would be to evaluate the drops and locks of the escapement as it currently is to find out where to start. Also, if the pallet fork has too much freedom (loose pivot holes) you will have a large power loss and inconsistant operation of the escapement.
     
  5. karlmansson

    karlmansson Registered User

    Apr 20, 2013
    2,563
    107
    63
    Doctor
    Linköping, Sweden
    Country Flag:
    I think the "fork travel stops" are usually referred to as banking pins. Or bankings if they are not pins. Some in older pocket watches can be adjusted by turning them in their settings.

    The problem with watches like that is that the escapement can have been adjusted at both the bankings and at the pallet stones. Hopefully whoever did the "adjustment" of the bankings in your watch left the shellac on the stones alone. When you are adjusting the bankings you will want to observe the roller jewel as it enters and exists the fork slot. It goes without saying that it needs to be able to enter and exit without interference but you don't want to give it too much freedom as this increases the lift angle and lengthens the time the balance is in interaction with the fork, which will affect time keeping.

    When you have made sure that the roller jewel is performing correctly you can take a look at the pallet stones. The escape wheel tooth should hit the locking surface when it drops, with a little distance to spare to the edge. As the balance continues turning it should allow the fork to turn a little bit further to allow the escape wheel tooth to lock fully. The proper depth of lock on a swiss lever should be about 1/3 of the impulse face of the stone. The force pulling the tooth up unto the stone is usually referred to as the "draw". Both lock and draw should be equal on both stones.

    You can adjust the lock by moving the stones in or out or by moving the bankings. Moving the bankings will affect the engagement between roller jewel and fork slot in a way that is different from moving the stones, as I hope you understand from my explanation above. Adjusting the stones is much trickier than moving the bankings. So you'll have to make a tradeoff on a worse action on the escapement or the potential messing up the stones. and their setting depth.
     
  6. psfred

    psfred Registered User

    Sep 25, 2009
    975
    4
    0
    The banking pins are used ONLY to set the travel arc of the lever. DO NOT use them to adjust locking!

    To set the escapement properly -- if you can move the banking pins, likely they were indeed peened down because they were moving when they should not have been -- remove the tension on the mainspring and allow the watch to stop. Apply just enough wind to lock the lever against one banking pin, you do not want the watch to run.

    Rotate the balance slightly and check for clearance between the safety pin on the lever and the roller table, there should be a tiny bit of movement of the lever allowed. The pin must not drag on the roller, and the "shake" should be quite small. The safety pin also must allow the lever to flip from side to side ONLY when the recess in the roller table is passing the line between the balance jewels and the lever jewels.

    Flip the lever over and check the other side. If necessary, turn the banking pins to get the correct clearance, and make sure the travel is the same on both sides. If you cannot achieve this state, you will have to fix whatever is wrong, very likely a damaged fork and/or bridge. If the lever has too much free play, the watch will not run properly no matter what you do, too much energy is going to be lost. The angle of the fork from the line between the balance jewels and the lever pivots must be the same, you may need to verify that the safety pin is not bent, or address distortions in the lever itself.

    Once you get the banking pins set, you can address the depth of the pallet stones.

    You MUST set the escapement in that order -- proper lever movement, then correct depth on the stones for correct escape wheel operation. Any other position for the lever is going to cause trouble, either by dragging the safety pin on the roller or knocking the impulse pin on the fork

    I would strongly advise you get one of the standard texts on watchmaking, or the Chicago School teaching courses which are available on DVD I think.

    Peter
     

Share This Page