Looking for info about landeron 51

Thread: Looking for info about landeron 51

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  1. #1
    Member AbslomRob's Avatar
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    Looking for info about landeron 51

    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).

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  2. #2
    Member Eeeb's Avatar
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    Re: Looking for info about landeron 51

    I'd try Watchmaking... that forum may know more.
    "Forever is composed of nows." - Emily Dickinson

    "The watch has to be surrounded by a history.
    You need more than just a great design. You need to create an atmosphere around the product.
    Who is the company behind it? Why are they using this material?
    People need to be able to identify the watch with themselves. It's based on emotion." - Ralph Furter

    ...that's just my opinion and I've been wrong before and will be again and might be now!

  3. #3
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    Re: Looking for info about landeron 51

    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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  5. #4
    Member radger's Avatar
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    Re: Looking for info about landeron 51

    Quote Originally Posted by Roland Ranfft View Post
    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.

  6. #5
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    Re: Looking for info about landeron 51

    Hi radger,

    Quote Originally Posted by radger View Post
    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

  7. #6
    Member AbslomRob's Avatar
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    Re: Looking for info about landeron 51

    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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  8. #7
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    Re: Looking for info about landeron 51

    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

  9. #8
    Member AbslomRob's Avatar
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    Re: Looking for info about landeron 51

    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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  10. #9
    Member radger's Avatar
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    Re: Looking for info about landeron 51

    Quote Originally Posted by Roland Ranfft View Post
    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.

  11. #10
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    Re: Looking for info about landeron 51

    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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