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  1. #1
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    Default Waltham pocket watch running slow ??

    I have a 0 size Waltham pocket watch that has been cleaned, thoroughly inspected, and re-assembled. It runs great, except that it is only running at 17,940 BPH. There are no apparent problems with pivots, cleanliness, hairspring action, or anything touching. The palllet action is correct, and the watch is in beat. It is consistent in all positions, and I can't find anything wrong. I wonder if it could be possible that at some time the hairspring or balance was replaced ??

    If I were to remove two opposing timing screws what would be the gain in BPH ??

    Thanks,

    Bill

  2. #2

    Default Re: Waltham pocket watch running slow ?? (RE: Bill V)

    Bill,
    Have you checked the mainspring?
    Brian C.
    Brian C.
    Chapter 149 Member

  3. #3
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    Default Re: Waltham pocket watch running slow ?? (RE: Bill V)

    Brian,

    I was just wondering if that could be the problem. The mainspring did appear to be a bit weak, but I have had others in the past that ran fine in the same condition and I thought that it would be OK. I could be wrong in this case. I think that I'll try replacing it and see what happens.

    Thanks,

    Bill

  4. #4

    Default Re: Waltham pocket watch running slow ?? (RE: Bill V)

    The mainspring should not affect the rate much. "Isochronism" means to keep the same time regarless of the power left on the mainspring. This is assuming that you a reasonable amount of power reaching the balance. You should have at least 1 1/4 turns (225 degrees) and best about 1 1/2 turns (270 degrees) on a full wind. If you do not have this much action, then you need to worry about that first and worry about the rating later.

    Also do not remove screws. You are off about 12 minutes a day. Removing a screw would be huge.

    It is always hard to find reasons for a slow watch. Most problems cause a fast rate.

    The first place that I would look for a slow rate would be the regulator pins. First make sure the hairspring is between the regulator pins. If it is slipping out, that would be your problem. Watch the hairspring between the regulator pins. You hairspring should be just barely free. You should just barely see the hairspring go from pin to pin as the balance goes back and forth. If there is excessive movement, because the pins are too far apart, this effectively makes the hairspring longer. It also causes a loss of isochronism.

    Another problem is that you balance rims may be bent out. True the balance in balance callipers and make sure the rims line up at the slits.

    If you have good action dial up and dial down, the regulator pins are OK, and the balance is true, then come back and we shall see about some other potential problems.

    Don



  5. #5
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    Default Re: Waltham pocket watch running slow ?? (RE: Bill V)

    I don't believe you want to actually remove the timing screws. Turning them out a bit may help, though (make sure you turn them the same amount).

    Of course, I'm referring to Mean Time screws - if you watch doesn't have any, you should be very careful about turning any of the other screws.

    Before you should turn anything, though, you should carefully examine the timing screws to make sure someone hasn't put a timing washer under any of them - that would most certainly make the watch run slow. If you find timing washers, try taking them out and replaceiong the screw and see if that brings you back to time.

    Harvey J. Mintz

  6. #6
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    Default Re: Waltham pocket watch running slow ?? (RE: Bill V)

    I decided that I'm going to replace the mainspring first and see if that has an effect on the rate. The balance arc looks good, but with the weak mainspring being the only thing I noticed during cleaning that wasn't quite right, I thought that I would start there and see what happens. It should be replaced anyway.

    I never thought to look for timing washers, and that would be a place to check if the mainspring doesn't take care of the slow rate. How much would timing washers change the BPH ?? I can also check the meantime screws and see if there's any room for adjustment.

    The balance is true, and the rate is consistent dial up and dial down. I did take a look at the regulator pins before assembling, but I think that I'll also double check there are see I missed something and if they need adjustment.

    I always hesitate to remove or cut timing screws, as the watch most likely once ran well with what is there now, and it should do the same again, provided it is original to the watch. If I exhaust all other options, then that would be a last resort. I know that it depends on the size and weight of the timing screw, but on average, is there an estimate of the rate change that would occur with the removal or addition of a pair of screws ?? I know that it would be more than what I am trying to achieve, but I am curious.

    Thanks to all for your help,

    Bill

  7. #7
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    Default Re: Waltham pocket watch running slow ?? (RE: Bill V)

    If you have to pull the hairspring over a very small amount to slide into the pins after the stud starts into it's hole, will that affect the rate? I ask this because I am experiencing the same problem. I am trying to learn and have almost no books to use.

  8. #8

    Default Re: Waltham pocket watch running slow ?? (RE: Bill V)

    Gary, yes that will affect the rate, but will usually cause the watch to run fast. Having to pull the hairspring to align it with the regulator pins means that the spring is not concentric. The distortions caused by the non-concentricity will tend to make a watch run fast with short arcs. There is a lot of information related to the hairspring shape and adjusting a hairspring. Some of the books written for hobbyists and beginning watch repairers have a some information for truing a hairspring.

    The problem as being discussed (to make the watch run slow) would require that the pins be loose fitting (or one or both missing) and the spring would self-align itself between the pins without any effort. The effect would be the same as if the spring were too weak, or the balance too heavy, increasing the time it takes for the balance to vibrate.

    As Don said above, running slow is more difficult to diagnose and correct than running fast. Most problems cause the watch to run fast. Don's list of possible problems seems very complete for a running slow condition unless the watch is overbanking.
    "Look, he is winding up the watch of his wit, by and by it will strike"
    Shakespeare The Tempest

  9. #9

    Default Re: Waltham pocket watch running slow ?? (RE: Bill V)

    Hi
    17,940 is really not that far off, so I would rule out any balance screws missing, or a mainspring problem.
    Here are a few things I would check. Some have already been stated.

    !. Hairspring has a rust spot on it.
    2. Hairspring has been bent so many times that it has a a spot that has lost it's "Spring" usually at the stud or collet.
    3. To much space between regulator pins.
    4. Roller jewel not tight
    5. Balance wheel has been trued incorrectly and is to large in diameter.
    6. Regulator has been replaced and is not the correct one

    Good Luck!

  10. #10
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    Default Re: Waltham pocket watch running slow ?? (RE: Bill V)

    Thanks to everyone for their help with this one.

    I have installed a new mainspring, and that did seem to increase the rate slightly to about 17,945. I went back over the watch with a fine tooth comb, and made an adjustment to the regulator pins. This brought me to 17,969, and the rest was achieved with a bit of a turn on each of the meantime screws. The watch is running right on now with the regulator just a bit to the high side.

    I had never made any adjustment with these screws before, and I was surprised at how much difference a 1/2 turn can make. To remove or add a pair of screws would be a huge.

    Thanks again to all,

    Bill


  11. #11
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    Default Re: Waltham pocket watch running slow ?? (RE: Bill V)

    A couple of questions I have about comments in this thread.

    >>at least 1 1/4 turns (225 degrees) and best about 1 1/2 turns (270 degrees)

    I am lost as to how 1 and 1/4 turn can equal 225 degrees. I thought 1 turn equals 360 degrees and add a quarter to that and you get 360 + 90 = 450.

    >>I don't believe you want to actually remove the timing screws. Turning them out a bit may help

    I am wondering how turning screws out helps to speed up the balance movement.

    Doesn't screwing the screw outward cause the balance wheel to have more centrifical force.

    Or maybe I get this one. The heavier the less the escapement can push the less travel of the balance wheel. Less travel equals faster...!

    Somehow seems kinda opposite.

    RJ
    [Discovery is about to be destroyed by the birth of a new star]
    HAL 9000: I'm afraid.
    Dave Bowman: Don't be. We'll be together.
    HAL 9000: Where will we be?
    Dave Bowman: Where I am now.

  12. #12
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    Default Re: Waltham pocket watch running slow ?? (RE: Bill V)


    One of the problems with watch repair is confusing terminology. Depending upon where and when a person learned watch repair their terminology will be different.

    To understand how 1 1/4 turns equal 225° it is helpful to look at a drawing of a balance wheel or even a circle. The definition of 1 turn it is for the balance wheel to swing 180° and then return. The problem is turns are referring to one complete oscillation whereas degrees are measured from a starting point to the end of the rotation.


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    Default Re: Waltham pocket watch running slow ?? (RE: Bill V)

    RJ,

    A good explanation for the adjustment of the meantime screws and the moment of inertia can be found on the Elginwatches.org website, under "History" and "Forgotten MasterPieces". Look in the section titled "Durabalance".

    Bill

  14. #14
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    Default Re: Waltham pocket watch running slow ?? (RE: Bill V)

    Thanks Bill V.

    Notes:

    http://elginwatches.org/history/fm.html

    Moment of inertia. Increasing weight away from hub increases moment of inertia and slows down escapement.

    RJ
    [Discovery is about to be destroyed by the birth of a new star]
    HAL 9000: I'm afraid.
    Dave Bowman: Don't be. We'll be together.
    HAL 9000: Where will we be?
    Dave Bowman: Where I am now.

  15. #15

    Default Re: Waltham pocket watch running slow ?? (RE: Bill V)

    What happens to a spinning iceskater when he brings his arms inward? Move the mass inward increases the speed, outwards decreases the speed. Now we are talking only about the meantime screws. These are long screws located at the end of the arms and 90 degrees from the arms. Do not mess with the short poising screws on the balance. Not all watches have meantime screws.

    When a balance swings 180 degress clockwise, it then stops and returns to the original position. It coast by the neutral point and continues another 180 degrees in the counter clockwise direction. We call this one turn. Some timining machines measure the action in degrees in ONE direction (180 degrees in our example). When you watch a balance action with your eye, you see the distance traveled in BOTH directions (one turn in our example) .

    Don

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