Jump to content

Jump hour movement, hour disc not advancing


Recommended Posts

So I got this swiss jump hour watch. Serviced and everything looked nice. When worn, I noticed that the motion of the hour and minute discs stops when hour should change. The problem seems to be that there's not enough power transmitting to the gears that should advance the hour disc. 

1.thumb.png.f3ce9ada83b0b5ac2dcf31d815eb05f2.png

The dial side of the movement draws power from the mainspring barrel. Here there's this brass wheel under the barrel. The wheel consists of two identical wheels. In the picture you can see that there's this brass wheel on top and a chrome on the bottom. The chromed bottom wheel draws power from the barrel and when the watch is running the two wheels should rotate simultaneously held by friction (I think). When time is set, the bottom wheel doesn't move but the top brass moves and changes the time and that's how it should be. Is the problem in too little friction between those two wheels as I suspect? When minute count is 55 the wheel starts slipping and there's not enough power to change hour. Can I increase the friction somehow? I don't have experience in these movements or this kind of wheels. Any info or guesses appreciated.

2.thumb.png.224d8c805641435b24bfa4f19badf789.png

Link to comment
Share on other sites

My guess was right. Slipping in that part was the cause. I could see a small gap between the wheels under a microscope so I figured out I might be able to push in a retaining ring you can see on top. I didn't dare use enough force in the jeweling tool so I eventually tapped it down in staking tool. Now the hour jumps and watch keeps somewhat decent time considering it's a pin lever escapement (Amida model something). At least the wheel train is pretty nice quality with small tolerances. 17 jewels.

4.thumb.png.f99ef5d019371386f273b5387b3a4a56.png 

  • Like 2
Link to comment
Share on other sites

  • 4 months later...

I just cleaned/oiled a BFG 866 (single jewel) movement and replaced the mainspring barrel with a NOS part. The two wheels that are rivited to the mainspring barrel cover were slipping (serve as a canon pinion) and power was not being transmitted to the wheels that power the date, hour and minute dials.

The new mainspring barrel fixed the problem BUT now the movement runs, rotates the minute dial but stops at 55 minutes because there doesn't seem to be enough energy to push past the hour dial jump.

Everything is clean/oiled, all pivots are good. Just looking at the balance wheel it appears that there is not enough amplitude to keep the movement running when the extra resistance from the hour dial jump is encountered.

Is it possible that the beat error is great enough to cause this type of problem? I don't have a timegrapher but am thing of getting one???

 

mainspring barrel and wheels.jpg

Baumgartner_866.jpg

20230611_102954.jpg

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.



  • Recently Browsing

    • No registered users viewing this page.
  • Topics

  • Posts

    • Interesting interpretation of "traditional". I would say that Loctite is definitely the up-to-date and appropriate stuff to use, however, it is a relatively modern solution. Before the advent of such esoteric solutions I believe that the "traditional" thread locker of choice may well have been a sugar solution. Once applied the water would evaporate and the sugar would crystalise, locking the threads tight.
    • @steve1811uk close but no cigar 🙂 I don't smoke anyway. I checked in my stock of parts and that's the closest I got to your dimensions. Good luck in your search. @RichardHarris123 I have an accumulation of all sorts of odds and ends that I acquired as a result of buying up the tail ends of old watchmakers estates. Usually after all of the great stuff has been stripped out, which means that the sweepings off of the workshop floor can be had for peanuts, but if you have the patience, can often be found to contain gold (both literally and figuratively 🙂 ). These came to me through on of those purchases. I doubt that I will personally be able to make use of even 10% of my accumulated stock, but having it, and knowing what I have, means that I can at least pass bits on to those who can use it whenever possible.
    • Hi and thank-you for your suggestions, as per Mark's instructions I checked my browser "Safari" and spell check and grammar was not ticked. So all sorted. Thanks CJ  
    • As an alternative, clear nail Polish, the advantage is you can have a manicure at the same time. 
    • I use Grammarly. It works really well and If English is not your first language, you will also receive help with formulations. There is a free version that covers most of my needs. It installs as a plug-in and works with all browsers and word processors.
×
×
  • Create New...