Japy Freres spring

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Hi All,
I’m trying to resuscitate a Japy Freres heirloom. It was going fine, though when winding the right arbor there would be some resistance and then a slip. Eventually one day, it ‘unsprung’ and now the barrel turns with the key. I’ve taken the movement apart and both barrel springs look okay with good spring action. I attach a photo of the movement. Why is the barrel turning with the key and what can I do?

[tmac1956]

Is the spring hooking up to the arbor? I’ve done several pocket watches where the spring will slip when wound because of this.

Thanks,
Tom

[arutha]

Tom is correct, the only reason for this would be either the inner or outer end of the mainspring is damaged and is no longer catching although it will take a very small amount of winding before slipping. If you intend to take the mainsprings out please make sure you wear gloves and safety goggles, they can bite!
Paul.

UPDATE!!! – It has just been pointed out to me by someone who is quite clever, that it looks like there is a wheel missing? Was this taken out for the picture? If there is a wheel missing there is nothing to stop the barrel turning?
Paul.

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Thanks folks. I think the spring in the barrel is okay, because it behaves just like its counterpart which is still winding up okay. Re; wheels – yes, I’ve taken one out in this photo. I’m wondering if the top right wheel in the photo, the one with the silver ‘core’ is alright. When the arbor is wound on this spring, the barrel turns together with the silver ‘core’ of this wheel. The outer circumference of the wheel does not turn????

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I attach a pic of the wheel I’m referring to. The smaller cog is turned by the spring, but the larger wheel does not move.

[arutha]

In that case it sounds like the wheel that does not turn is loose on the arbor. This will stop the power transmission to the rest of the gear train and will allow the barrel to just turn. If I remember rightly on these french clocks the pinion gear(the silver one) is cut on the arbor(the axle) and then part of it is turned down and the wheel is riveted on to it. To repair this properly you would use a brass split stake in a vice which would allow the pinion gear to sit in a hole, the wheel would be facing up and would give you access to the part of the turned down pinion gear which just comes through the hole in the centre of the wheel. You would then use a punch with the outside diameter no bigger than the diameter on that part of the pinion and which also has a hole in the centre to allow the arbor to pass through, and just keep tapping at it until the wheel is again solid on the arbor. If you do not have the tools to do this your only other option is to try some of the strong loc-tite glue mentioned a couple of posts ago. Being that this wheel is so close to the barrel it will be taking a lot of power and I dont know if this would be a permanent fix i.e. how long a glue joint would last.
Paul.

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That was just the information I was hoping for Paul. After reading your post, I was able to take the wheel off the axle and see the mechanism in detail. I attach a photo. It is obviously worn down. I have glued it back in place and will let you know how we go! Do you think soldering these parts together would work? I will seek out spare Japy parts in the meantime! Thanks for your help.

[arutha]

Yes you could solder the wheel on to the arbor, it is generally frowned upon to use solder for repairing a clock and I couldn’t recommend it if it was a customers clock but if it is your own and you are happy to do that then yes. Just clean it up as best you can afterwards and make sure any flux is washed out as this can play havoc with brass if left in there.
Paul

[Bob Tascione]

Hi all,
I thought I would jump in on this topic as I see a possible safety issue here.
LocTite is an amazing adhesive used in many industries. As David recently mentioned in a post under another topic it is used OFTEN in the toolmaking industry. In many cases in tool making we use it “in addition to” and not in place of a mechanical fit or bond. Examples would be locking a nut or screw in place, securing a light press fit dowel into a base plate or part etc. Where a strong bond is critical it’s best to have as much going for you as possible. In the case of a clock movement a great deal of potential power is sitting behind those barrel teeth which are meshing with that wheel pinion. That mainspring would be happy to release it’s full evil force in an instant if given the chance…sooo my personal feeling is that a good mechanical fit is necessary first, and the addition of loctite could also be helpful. These mechanical (riveted) connections do sometimes fail as your clock clearly demonstrates so adding some LocTite after properly securing the wheel to its arbor should help keep it from occurring a second time.

A sudden release of power can easily damage movement components and worse yet cause personal injury while winding or working with a movement when under power. As Paul mentioned properly securing the arbor would be the very first thing to do.

Hope this helps,
Bob

[arutha]

Well spotted Bob, I didn’t even stop to think about the glue letting go and yes you are quite correct, It could not only cause personal injury but also possible damage to the clock. 😳
Even if you solder the the wheel back on I am not sure how well it would hold up against a fully wound mainspring. If you don’t have the means to rivet the wheel back on maybe looking for a spare could be the best option.

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