Can dirt cause a verge fusée movement to "slip"??

Discussion in 'European & Other Pocket Watches' started by Ansomnia, Jul 15, 2007.

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  1. Ansomnia

    Ansomnia Registered User

    Sep 11, 2005
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    Hi, I wonder if the experienced and knowledgeable folks on this forum can comment on a problem with a watch.

    It's an English timepiece, circa early 18C. The crown wheel seems to slip by the pallets and winds down immediately when I try to wind the watch up. I stop immediately of course and the watch only winds down a short length of chain but it is very worrisome. The watch seems to be in very good original shape otherwise.

    I examined it carefully under high magnification and the verge is properly seated and turns freely. The hairspring looks fine. I also checked the crown wheel for endshake and it seems to be reasonable.

    So I wind it up a tiny bit again. Lo and behold, it's now running properly. I wind it up a bit more and it's ticking along just fine.

    Could it be just dirty verge pivots? I can see black whale oil or something in the pivots. I wonder if the light from my microscope may have loosened the dirty oil.


    Michael
     
  2. Smudgy

    Smudgy Registered User
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    May 20, 2003
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    Re: Can dirt cause a verge fusée movement to

    It shouldn't. Either one pallet or the other on the verge should be in contact with the wheel at all times. Check to see if the pivot holes have enough wear to allow the verge to shift far enough out of position to allow the wheel to turn without coming in contact with the pallets, or if some of the teeth on the wheel are damaged. It's odd that it stopped free-wheeling.
     
  3. EmmaR

    EmmaR Registered User

    Re: Can dirt cause a verge fusée movement to

    another thing to check is the end shake.. some have very little difference in diameter between the pivot and the balance staff. if it slips sideways they can skip like that.. might not take as much wear as you think to achieve that..

    maybe this will help.. *EM*
     
  4. EmmaR

    EmmaR Registered User

    Re: Can dirt cause a verge fusée movement to

    I'll add to that.. wonder if it still runs upside down? could be a pivot problem.

    otherwise i'd look for a bent crown wheel tooth.

    rather you than me.
    *EM*
     
  5. Ansomnia

    Ansomnia Registered User

    Sep 11, 2005
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    Re: Can dirt cause a verge fusée movement to

    Thanks for your suggestions and comments Emma and Smudgy. Well, I guess I was a bit premature.

    I wound up the watch just a bit again this morning and the movement is "free-wheeling" again. It catches and then slips and just won't stay in beat. I placed the watch under my microscope and took a good look at the pallets and the crown wheel. Most of the teeth on the wheel have blunt ends. Some have metal bent right over. I don't know what could have bent so many teeth at once but that would be the cause of the "free-wheeling" for sure.

    When it was running I did notice the movement sounded weak. I could hardly hear it tick but it was keeping time for about 2 hours. It did stop occasionally when I tilted the watch a certain way.

    I did check for endshake on the crown wheel and there is just a tiny bit, not enough to explain why the teeth would be bent like this. I also looked at the verge. The balance staff seems to be properly seated but is also very loosely held down by the cock. The cock is not tightly screwed down and the assembly has a springy feel to it. I wonder if the verge is original to this watch.


    Michael
     
  6. Tom McIntyre

    Tom McIntyre Technical Admin
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    Re: Can dirt cause a verge fusée movement to

    If the watch free wheels there is a good chance the crown wheel teeth will be damaged. The depthing of the verge pallets is a bit delicate if you want the watch to run well. It may have been left at a very critical position. Once the first slip occurs, the impact could move things a bit and allow further slippage. Once the teeth are bent, it will continue to slip.
     
  7. Ansomnia

    Ansomnia Registered User

    Sep 11, 2005
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    Re: Can dirt cause a verge fusée movement to

    Thanks for your advice Tom. I think you've all hit on the cause of the problem.

    I managed to get a good look and some close-ups of the crown wheel. Most of the teeth have bent tips, some worse than others. How would you describe the state of this crown wheel. In my limited experience, I would say it is not repairable. I wonder if it can be replaced and how much that might cost.

    I haven't checked the pallets yet but I imagine they may be damaged as well given the pounding these teeth have witnessed.

    What do you think?


    Michael
     

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  8. Tom McIntyre

    Tom McIntyre Technical Admin
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    Re: Can dirt cause a verge fusée movement to

    I believe the depth is adjustable with a sliding dovetail. If the tooth forms are cleaned up there is a good chance the crown wheel can still be used.

    This accident happened to these watches quite a bit 250 years ago and they were designed to be repairable.

    The pallets are pretty sturdy. I would be surprised if this affected them much. The pallets wear out in a running watch from abrasives getting in the crown wheel and wearing grooves in the pallets. A cheap repair for that problem was to move them up or down to a fresh surface.
     
  9. Ansomnia

    Ansomnia Registered User

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    Re: Can dirt cause a verge fusée movement to

    Tom, thanks for your insights to this problem.

    I am new to this area so I hope you and others will feel free to correct me if I make a mistake in my understanding of the mechanisms involved. I'm trying to think through what sort of repairs might be needed.

    I imagine the tips of the teeth will need to be cleaned up at the very least. But since the height of the teeth does not appear to be restorable, I think the crown wheel will have to be brought closer to the verge to restore the drop. I suspect this can be done by turning down a bit of the arbor adjacent to the pivot, in effect moving the pivot up the arbor a bit. I also suspect the follower of the counter-potence at the other end of the arbor can be moved in to restore proper endshake (see photo - BTW, the photo got rotated 180° when it was uploaded - arbor should point the other way to be consistent with other photos).

    However, I am wondering if there is sufficient clearance between the dovetail plug which presents the pivot hole for the crown wheel arbor and the hub of the crown wheel. I've attached a couple of photos of the area. I cannot get a straight shot from the edge as the crown wheel is in the way but I think you can make out the approximate clearance viewing from a slight angle.

    What do you think? Can the crown wheel hub be brought closer to the potence?


    Michael


     

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  10. Tom McIntyre

    Tom McIntyre Technical Admin
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    Re: Can dirt cause a verge fusée movement to

    Your problem is similar to one I had worked on last year. In the case of my watch a new verge was made, but the crown wheel was salvaged. My restorer had to remove some metal from the arms of the crown wheel to get enough room to make it all work. the dimensions are pretty small, so not much metal needed to be removed.

    The photograph and the work were both done by John Wayper, an excellent restoration specialist in the London area.
     
  11. Ansomnia

    Ansomnia Registered User

    Sep 11, 2005
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    Re: Can dirt cause a verge fusée movement to

    Tom, thank you very much for sharing with me the repairs made to your watch. I was very intrigued and I found your website or at least some webpages you had put up pertaining to a presentation of PowerPoint slides showing a number of pocketwatch subjects.

    I am actually evaluating this watch and was wondering if the free-wheeling problems would present too much of a challenge to restore. I really appreciate your input on this. It looks like your watch had a very similar problem with the crown wheel. I'm glad to see your restorer was able to salvage it. It looks like it was made by quite an important maker.

    If it is alright with you I would like to ask for John Wayper's contact information in case I need to follow up on this restoration. I'll forward you my email address.


    Michael
     

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