Winding stem welder

Discussion in 'Watch Repair' started by RJSoftware, Nov 4, 2019.

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  1. RJSoftware

    RJSoftware Registered User

    Apr 15, 2005
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    Hello all.

    I wish there was such a thing as a winding stem welder.

    It would be very usefull. What I notice is most times the stems break at the threaded rod portion. I have had some success with the stem extenders which have a little coupling. But, all to often they dont work as the stems are small and cramped for space.

    I can cut a stem from scratch in the lathe and thread it, but its a ton load of work, even modifying an existing stem to fit is bothersome hit/miss-snap.

    It would be so nice to be able to zap a piece of threaded stem rod right to the break. I dont believe soldering would be strong enough.

    Ive seen other micro welders but cant recall much about them. I think one was for dial legs. Anyway, I wonder what kind of jig I could set up and how much amperage. I wonder if a 12v car battery and some temporary switch.

    I dont know much about welding but I bet it could work.

    Thoughts/opinions/advise appreciated.
    Rj
     
  2. RJSoftware

    RJSoftware Registered User

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    this kind of welder looks promissing. Used to spot weld batteries together. The search category is under micro welders.
     
  3. Jerry Kieffer

    Jerry Kieffer Registered User
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    May 31, 2005
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    Winding stems are generally made of carbon steel and hardened/tempered tough but not brittle hard where they would easily snap off. Rockwell hardness has been in the low 50`s on the one or two that I tested over the years. They of course can be welded, but depending on how fast they cool, the joint could be annealed soft or brittle hard or a mixture of both.
    As such for dependability, they should be hardened/tempered after the welding process in a controlled environment. However, it is unlikely one would know the exact alloy and exact hardening/tempering settings making the process trial and error to a degree.

    This is a question that occasionally comes up in class, thus one option is demonstrated in the NAWCC workshop WS-117.

    If the watch has a basic common style crown or one can be utilized, basic crowns are very easily and quickly machined where existing stem threads remain. As such, when machining, the post can be extended to pick up existing stem threads and machined slightly larger to compensate for case wear if required. The procedure using basic machining practices is as follows.


    (1) Stock is mounted and knurled per first photo


    (2) Post is machined to length/diameter plus spot drilled/drilled second photo.


    (3) Crown is parted off third photo.


    (4) If the crown requires undercutting, it can be done using a Micro profiling boring bar per fourth photo. (Done before parting)


    In class, some demonstration procedures are timed for real life evaluation and practicality and then compared to other procedures. The fifth photo shows a crown from bar stock to what you see, in four minutes and thirty eight seconds. Undercutting would add a minute or two.


    Jerry Kieffer

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  4. RJSoftware

    RJSoftware Registered User

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    Interesting, never considered extending the crown post.

    The watch that inspired this thread is very low end. The owner hasn't bothered to pick it back up. I doubt he will. I took one good stab at modifying a close match but failed and broke the close matching stem.

    I think it might be worth while to give the stem welding a try. I can always anneal it after to avoid the brittle. Use the oil quench after super heat.

    I will have to experiment to see what is best way to clamp the pieces so they conduct properly and dont suffer damage.
     

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