Hamilton 940

Discussion in 'Watch Repair' started by RyanM, Jun 29, 2019.

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

    RyanM Registered User
    NAWCC Member

    Feb 27, 2019
    73
    37
    18
    Male
    Country Flag:
    Region Flag:
    I have a Hamilton 940 which I've cleaned and lubed. The amplitude is very weak while dial down and this is as strong as it gets, dial up it just stops. There seems to be far too much play in the pallet fork, or end shake. I've inspected the jewels and all 4 pallet fork jewels seem to be in good condition and set properly, having the proper distance. The pallet fork seems to have good pinions, but I don't really have anything with which to compare.

    I would think that if the pallet fork were falling out of position while dial down, it would disengage from the escape wheel and the watch would simply spin at max rate, not stop.

    The watch is a later 940 which went to the finishing department on October 20, 1911 and with serial number 924655, meaning it is double roller, has the one piece pallet and fork, and of course the motor barrel.

    The behavior is similar to watches I've had where there was a chipped jewel, however all the jewels seem to be fine when viewed through a 10x loupe.

    I'm at a loss for what could be causing this watch not to work properly and have spent many a day taking it apart, inspecting it, and reassembling. I've cleaned it a few times, keep looking over the hairspring for dust or hairs, but just can't seem to find the issue. The only thing I come back to is the end shake, but I'm not sure if excessive end shake could cause this, or even if the end shake is actually excessive for this watch.

    Any insight would be highly appreciated. I'll post pics as requested since I'm unsure what would be useful at this point.
     
  2. richiec

    richiec Registered User
    NAWCC Member

    Feb 24, 2007
    6,717
    537
    113
    Male
    automotive warranty inspector
    Brick, Ocean, NJ
    Country Flag:
    Region Flag:
    Sounds like a balance jewel or staff issue, maybe a pivot is bent slightly, grooved? the end stones aren't chipped are they? Do the wheels moved readily without the pallet?
     
  3. pocketsrforwatches

    pocketsrforwatches Registered User
    NAWCC Member

    Feb 13, 2008
    274
    10
    18
    Retired from IBM, now a Watchmaker
    Ticonderoga, NY
    Country Flag:
    Region Flag:
    Isolate. Let down the mainspring and remove the balance and pallet assembly. Give a couple of clicks to the mainspring and watch the train movement. It should be smooth and with a good mainspring the escape wheel should run backwards a bit when it runs down. Put the balance on the plate without the pallet and set the balance in motion with a twist of the wrist and check that it oscillates smoothly in all positions. It should oscillate for at least a minute in dial up and dial down positions. In my experience most of the time something in the balance area is at fault.

    Roger
     
  4. RyanM

    RyanM Registered User
    NAWCC Member

    Feb 27, 2019
    73
    37
    18
    Male
    Country Flag:
    Region Flag:
    The end stones seem fine, but the hole jewel that came out of the balance cock looks... fuzzy. Perhaps cleaning it again will do the trick. Below are some photos of the jewels and staff ends. I didn't remove the hole jewel from the balance cock until now, the cap jewel came out with the ring on which the regulator pivots leaving the hole jewel in the balance cock, and I cleaned it in place.

    20190629_093257.jpg 20190629_093634.jpg 20190629_093719.jpg 20190629_093835.jpg 20190629_093934.jpg 20190629_094739.jpg
     
  5. RyanM

    RyanM Registered User
    NAWCC Member

    Feb 27, 2019
    73
    37
    18
    Male
    Country Flag:
    Region Flag:
    Will try that when I get back home, thanks!
     
  6. gmorse

    gmorse Registered User
    NAWCC Member

    Jan 7, 2011
    11,285
    1,583
    113
    Male
    Retired from Xerox
    Breamore, Hampshire, UK
    Country Flag:
    Region Flag:
    Hi Ryan,

    From your pictures, the tips of the staff pivots are both flat, and there's rather too much debris on everything. How are you cleaning it? Now, it may be the way the impulse jewel is fitted, and what I'm seeing is the shellac, but is there any oil on it? Doing Roger's tests will tell you more.

    Regards,

    Graham
     
  7. RyanM

    RyanM Registered User
    NAWCC Member

    Feb 27, 2019
    73
    37
    18
    Male
    Country Flag:
    Region Flag:
    I clean in an ultrasonic machine, then rinse and go over things again under the loupe, although this being the first time I removed the upper balance hole jewel, I was shocked at how many fibers were left on it and I fully intend to clean it all again. I cleaned the oil off the jewels for the pics and probably left more debris behind. I'll also do Roger's after I clean it again, all this after I finally make it home. I generally oil the roller jewel with a small amount of 9100, just enough to leave a thin film of oil and not enough to be thrown off while in operation. Thanks for the input Graham, I'll check the roller jewel as well and shift it as needed.
     
  8. gmorse

    gmorse Registered User
    NAWCC Member

    Jan 7, 2011
    11,285
    1,583
    113
    Male
    Retired from Xerox
    Breamore, Hampshire, UK
    Country Flag:
    Region Flag:
    Hi Ryan,

    This really isn't necessary, it should be left clean but quite dry. Which Synt-HP are you using, because this series is intended for high-pressure applications such as centre wheels and barrel arbors, and any of them will have a detrimental effect if they're used on the impulse pin.

    Regards,

    Graham
     
  9. NC Plumber

    NC Plumber Registered User

    Jan 15, 2011
    413
    22
    18
    Male
    Country Flag:
    It looks to me that the hole in the jewel is off center ? It may be the angle of photo causing it to appear that way ? In one of the pictures it looks like the hairspring is out of level, is the balance wheel resting upon the hairspring stud in that picture ?
     
  10. Samie Smith

    Samie Smith Registered User
    NAWCC Member

    Mar 22, 2012
    105
    26
    28
    Male
    watchmaker
    Monticello ky.
    Country Flag:
    Not to repeat what has already been posted as someone posted check the train to see if it is free also check the mainspring you should always use a white alloy mainspring that is at least .018 mm thick on the 940 ,,something I do ever time I service a watch is remove the mainspring then I install the mainspring arbor and mainspring lid without the mainspring in the barrel and see if the barrel spins free on the arbor if not you may have to polish the barrel arbor.

    You say it stops in dial up postion remove the balance jewel from the cock and set it on the upper pivot of the balance the pivot of the staff should come up through the balance jewel enough to hit the cap jewel if not it will wedge and stop the balance.
     
  11. Peter John

    Peter John Registered User
    NAWCC Member

    Sep 4, 2018
    288
    115
    43
    Male
    Watch and clock repair
    Scottsdale, Arizona
    Country Flag:
    Region Flag:
    I think any oil on the impulse (are you referring to the index jewel?) is a no-no.
     
  12. RyanM

    RyanM Registered User
    NAWCC Member

    Feb 27, 2019
    73
    37
    18
    Male
    Country Flag:
    Region Flag:
    Yes, just the angle, the hole is centered. And again yes, just resting on the hairspring in the other.

    Got it, no oil on the impulse/roller jewel. I suppose I should go back over my other watches and do them all properly as well. Thanks for the info!

    I'll get to work on it soon, trying everything suggested so far and post an update once I have. Thanks to all for your input so far!
     
  13. Skutt50

    Skutt50 Registered User

    Mar 14, 2008
    3,556
    125
    63
    Male
    Gothenburg
    Country Flag:
    In addition to Rogers suggestions in post #3 above I also test the pallet fork. Mainspring fully let down, no balance installed. The pallet fork should fall from one side to the other when you tilt the movement.
    I have had more than one movement where the fork looks good but fails to move by its own weight. Anything from dirt or damaged pivots, faulty or damaged jewels to bent cocks/bridges........ All of these can significantly slow down or even stop a watch.

    I also test the pallet fork with some power on the main spring. It should jump distinctly between its end positions and for the full turn of the escape wheel.
     
  14. RyanM

    RyanM Registered User
    NAWCC Member

    Feb 27, 2019
    73
    37
    18
    Male
    Country Flag:
    Region Flag:
    Alright, I got it working very well, but before I say how, I will go over the tests and results:

    Removing the pallet fork and checking if the escape wheel went backwards before stopping, it did for over a full revolution, therefore I concluded the train was in good shape.

    Checking the balance wheel oscillated well in all positions without the fork, it did so I ruled out the balance wheel.

    Now my suspicions about the pallet fork were increased, especially the excessive end shake and side shake at one of the jewels.

    The pallet fork moving under it's own weight with the escape wheel and balance wheels removed, it did not.

    At this point I examined the pallet fork's pinions, they seemed straight and clean. Next I examined the jewels, removing both the upper and lower cap/endstones and hole/pivot jewels. They seemed fine as well, no cracks or dirt.

    However, I noticed the holes were not the same size. I got to looking over the settings and plates and saw where (fortunately) a less careful repair had left toolmarks which traversed the setting and plates. The marks on one cap jewel didn't match with the marks on the plate. Examination of the adjacent balance wheel jewel setting also showed mismatched tool marks. And it struck me that the tool marks would match if the jewels were swapped... it seems that I had incorrectly marked the jewels while doing the initial cleaning and had put the wrong jewels in the wrong spots.

    After swapping them back, I have a whole different problem but a very fixable one; the amplitude is now around 370° in dial down position. I have a supply of balance screws, so I'll get it sorted out quickly now.

    I'd like to thank all who replied, I learned quite a bit about isolating a problem and determining where to look when things aren't going well. Ultimately, while I do label which jewels go where, I must have got myself confused at one point and caused the problem myself. I wouldn't have found where I went wrong on my own this time without your help, so thank you all for giving me the tools to solve not only this issue but many more to come.
     
  15. gmorse

    gmorse Registered User
    NAWCC Member

    Jan 7, 2011
    11,285
    1,583
    113
    Male
    Retired from Xerox
    Breamore, Hampshire, UK
    Country Flag:
    Region Flag:
    Hi Ryan,

    That's good news, and now to address the balance amplitude. If the balance is original and un-molested and if it's running to time, adding more weight will slow it down but may not influence the amplitude very much. It would have come from the factory running to time, so if there's no evidence of it being altered at some stage, the problem of excessive amplitude, usually evidenced by the balance knocking, (the impulse jewel hitting the outsides of the lever fork), may lie elsewhere, perhaps in an incorrect and over-strength mainspring?

    If a hole jewel doesn't have a cap jewel, there's little reason to take it out of the plate for cleaning. Of course, if it's damaged that's a different matter! (By the way, lever arbors don't have pinions, they just have pivots).

    Regards,

    Graham
     
  16. RyanM

    RyanM Registered User
    NAWCC Member

    Feb 27, 2019
    73
    37
    18
    Male
    Country Flag:
    Region Flag:
    Most certainly it wasn't as shipped from the factory; it was in pretty rough shape at first, I had to true it round and to some degree flat as well. Although, after adding some balance screws, the amplitude has increased to around 410°, so I'll just remove them and check the timing. As I understand it, timing errors are at a minimum across positions when the amplitude is at 220° and magnified greatly if the amplitude is under that, and magnified to a far lesser extent when the amplitude is over 220°, and in general when a watch is dial down/up or horizontal the amplitude will be higher then in the vertical positions, so when testing at a horizontal position you want to see close to 270°. However, I've had watches do well while at 300° in the horizontal and 250° in the vertical, so perhaps this one will be fine at 370°? I'll have to wait until I can borrow a timing machine to find out, I suppose.

    Below is a pic of the balance wheel as i recieved it.

    IMG_20190618_174812_863.jpg
     
  17. gmorse

    gmorse Registered User
    NAWCC Member

    Jan 7, 2011
    11,285
    1,583
    113
    Male
    Retired from Xerox
    Breamore, Hampshire, UK
    Country Flag:
    Region Flag:
    Hi Ryan,

    How are you measuring the balance amplitude?

    Regards,

    Graham
     
  18. RyanM

    RyanM Registered User
    NAWCC Member

    Feb 27, 2019
    73
    37
    18
    Male
    Country Flag:
    Region Flag:
    Graham,

    I've been measuring it as degrees of rotation, but you asking me that has me doubting myself again. I measure by taking slow motion video of the balance wheel in motion, marking where one arm comes to rest in one direction then again when it comes to rest in the other and using a drafting tool to measure the angle above or below 360°. Maybe this isn't the correct method and if not, I'm grateful if you could set me straight on the subject. I'm still fairly new to all this and still have a lot to learn.

    Thanks,

    Ryan
     
  19. gmorse

    gmorse Registered User
    NAWCC Member

    Jan 7, 2011
    11,285
    1,583
    113
    Male
    Retired from Xerox
    Breamore, Hampshire, UK
    Country Flag:
    Region Flag:
    #19 gmorse, Jun 30, 2019
    Last edited: Jun 30, 2019
    Hi Ryan,

    That's a perfectly valid and precise way of measuring it. I was just wondering if you were using a timing machine and getting the amplitude from that, because the machines calculate the amplitude using the lift angle as a reference, and the displayed amplitude will be inaccurate if the lift angle is wrong. They usually default to 52º, which may not be correct for the specific watch being measured.

    Regards,

    Graham
     
  20. praezis

    praezis Registered User

    Feb 11, 2008
    462
    26
    28
    Germany
    Country Flag:
    Region Flag:
    Ryan,
    from your description I suspect that you take the the full swing as amplitude (410° ...). However amplitude is the half of it: it is the angle from rest position to one reversal point. Here the 270° horizontal rule is valid.

    Frank
     

Share This Page