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Discussion Starter · #1 ·
I picked up this movement from Argentina the other day; non-runner (only $35, which seemed fair); the balance staff pivot is broken. An easy enough fix, assuming there isn't anything else wrong with it. However, I was looking up balance wheels and staffs on Jules Borel, and they list a number of different staffs; I'm not sure what I need here. Anyone know how I should figure this out?
Also, the database says that this was made for a period of about 40 years; any idea how to narrow the age? I noticed a "brevet" mark on the dial side, which I assume puts it closer to old end (and the dial style suggests late 40's to me).

Dial.JPG Movement.JPG Keyless.JPG
 

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I'd try Watchmaking... that forum may know more.
 

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Hi Rob,

if you replace the complete balance with staff and spring, you can take any for tht 48-family, although a modern ring balance looks strange in a movement from the 40s.

But better calculate what you need additionally. At least stem, operating lever, and reset lever are missing, And it looks as if almost all hand post are broken off. The costs for the missing or damaged parts would likely buy you a complete running movement. And as donor it is also useless because all parts which ever break on this calibre are either broken or missing.

Reggards, Roland Ranfft
 

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Hi Rob,

if you replace the complete balance with staff and spring, you can take any for tht 48-family, although a modern ring balance looks strange in a movement from the 40s.
Reggards, Roland Ranfft
No,

I'm sorry Roland, but any L48 family balance assembly simply will not do.

It should be understood that there are differences in the critical dimensions such as the length
of staff and dimensions of the pivot between the different types of L48's dependent upon the type
of jewelling fitted.
Inca, Supershock and non shock types such as Robs all have different lengths of staff, as much as a 10th mm
difference in the types.

Rob, there are five types of staff for the L51.
Rule out Supershock, Inca and annular balance without screws and we are left with two types...
Ronda 1225 and Ronda 4064.
The only difference between these two staffs is the collet seating dia, the 1225 is 0.70mm dia whilst the
4064 is 0.75mm dia. Remove the hairspring and take this measurement and then you'll have the staff type
you need.
 

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Hi radger,

I'm sorry Roland, but any L48 family balance assembly simply will not do.
For me it does well, because the play of the staff is usually enough to take all staff lengths between 4.17mm (no shock device) and 4.27mm (Super Shock), and if in a particular case not, I have no problems to push the jewels on the dial side up to 0.1mm further.

But this is no secret: Flume, the biggest wholesaler in Germany offers only one staff for all variatiants of the 48-family. They bought them from Ronda, and since they are only 4.15mm long, I suspect the differencees between the Ronda items 1225, 3129, 3542, 4064, 4937 exist only in printed form.

Regards, Roland Ranfft
 

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Discussion Starter · #6 ·
Thanks Roland and Radger; that's very useful. I imagine if you had to, you could simply buy the longer staff and turn it down on a lathe to fit? Really need to learn how use my lathe...
 

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Hi Rob,

I'd not shorten the staff, but shift the jewels on the dial side (Seitz tool). The more pedestrian solution are some of these hour wheel washers under the cock. But I must admit it never happened to me - either luck or because the variants with shock device never require replacement.

Regards, Roland Ranfft
 

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Discussion Starter · #8 ·
Do you know off hand what the patent mark refers to? It doesn't have a patent number on it. I'm assuming that knowing the patent would allow me to date it within about 10 years of the patent registration.
 

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Hi Rob,

I'd not shorten the staff, but shift the jewels on the dial side (Seitz tool). The more pedestrian solution are some of these hour wheel washers under the cock.
Regards, Roland Ranfft
A tenth of a millimeter is quite a lot in the length of a balance staff, as much or more than the total end shake between the
endstones. By what means do you pack out the dial side endstone to retain the endshake after you've pushed the jewel up... I'm always
interested to learn new techniques.
I've found that even with the correct staffs some adjustment of diameters is usualy necessary, especially to the roller arbor but
the critical length is invariably accurate when the correct staff is acquired.
 

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Hi Rob,

don't actually know it, but as Charles Hahn made the first chronographs with this kind of cam operation, I suspect the patent refers to it.

But it will be not easy to research: Dubois-Depraz was involved in almost every chronograph design, but nevertheless is scarcely mentioned in the literature. Back to Landeron: Hahn made only the base movements. The chrono assembly was designed and produced by Dubois-Depraz, and I have no idea who deposited according patents.

Regards, Roland Ranfft
 

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Hy radger,

A tenth of a millimeter is quite a lot in the length of a balance staff, as much or more than the total end shake between the endstones.
Watch the shake of an average Landeon; they are not the general pattern for precision.

Anyway, lets take the facts, which I suspect to exist only in paper form:

1) The only difference between hub and cock jewel are two diameters of the hairspring collet: 0.70 and 0.75mm. I guess it is not worth discussing what to do, since often tolerances at this place are bigger.

2) Between hub and dial jewel there are two diameters of the roller collet: 0,48mm (few) and 0,49mm (most). At least this is within usual tolerances of replacement staffs.

3) The most important left, is the differing length between hub and cap jewel. The Incabloc staff is 0.08mm longer, and the (very rare) Super Shock version even 0.1mm. Still no challenge for a hobbyist like me, and the less for a watchmaker. Moreover you never need to adjust the whole difference due to the already existing end shake.

By what means do you pack out the dial side endstone to retain the endshake after you've pushed the jewel up.
Take the jewel tool (Seitz, Horia) to press the hole jewel as far as necessary, worst case 0.1mm though. On the cap jewel nothing must be done, because it rests on the hole jewel anyway. And if it disturbs that its plate doesn't sit plane, look at the pic above: The jewel sits deep enough in its plate to push it also 0.1mm out (without loosing it).

However, this all is theory. I don't replace staffs often (my watchmaker does it more efficiently). But among these few, Landerons are frequent canditates, because almost every chronograph cadaver is worth get it running. I well adjust balance jewels now and then to compensate for badly fitting staffs, but on a Landeron it was never necessary - as mentioned above: probably luck.

Regards, Roland Ranfft

BTW: Remember Robs question and my first response. Rob wanted to replace the complete balance assembly, and the suggested screw balance will fit anyway.
 

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Interesting techniques to modify the watch to fit the part rather than the other way around.
Typical end shake clearance between the endstones on a 13 ligne watch is 0.02mm. To move
a jewel out by 0.1mm and then screwing the endstone down onto a 0.1mm oversized staff would
stop the watch I think...but then that's only theory as I've never tried it but I can visualise the problems.
A new deeper endstone setting could be made and of course a good repairer could also carry out this modification
but I think the best answer would be to fit a staff of the correct length...no criticism of your repair techniques intended.
 

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Hi radger,

To move a jewel out by 0.1mm and then screwing the endstone down onto a 0.1mm oversized staff would stop the watch I think
Be sure it does not. Before the (with one screw mounted) cap jewel setting presses the hole jewel back it will be bent.

...but then that's only theory as I've never tried it
No need to speculate. I did it several times and it never failed. For many old watches a nearly fitting staff is the more economical solution than turning a new staff.

of course a good repairer could also carry out this modification
I'm all but a good repairer. My watchmaker does almost everything in a quarter of the time I need. But I collected all necessary equippment to do many things for hobby purpose (and yes, I learned much from my watchmaker).

but I think the best answer would be to fit a staff of the correct length...no criticism of your repair techniques intended.
Yes, but I'm pocket watch collector, and most old calibres can't be identified, and even less a fitting staff can be located anywhere in the world. And back to modern (still old) calibres like here: If only a bearing must be adjusted a little, I prefer the minutes to do so instead of wasting hours to locate the right part.

And if a bearing is shifted, all relations remain original, and even better, if later again the right staff is mounted, all can be turned back to the original state. No repair should be irreversible.

Regards, Roland Ranfft
 

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Yeh, I know what you mean in regards to locating correct staffs for vintage and antique... for a lot
of models it is all but impossible. Often I'll look out a finished staff which is close in dimension, and rework with a simple
made soft iron polisher, dressed on emery and loaded with diamond pastes then finish with diamantine.
I try to avoid using the graver to rework a finished, hardened staff as they can be a ..... to cut but diameters and seats can
be quickly reduced and repolished using this grinding technique, underhand or overhand on the lathe.

To shorten a staff and rework the pivot I'll use the Jacot tool and yes, I've had to let in jewels to adjust shakes.
It's amazing the variety of hacks watchmakers, and tinkerers have used to adjust end shake on the staff. I've saw
the dial washers, cig papers and raised burrs commonly called pigs ears made by graver points, under heels and toes
of the cock. I've saw slithers of polished steel set between endstone and pivot jewel, I've saw lots of things and I marvel.
 
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