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Thread: Repair rack and pinion lock for extension rail

  1. #1

    Join Date
    Jan 2020
    Location
    Denmark
    Posts
    4

    Repair rack and pinion lock for extension rail

    Hi,
    I am working on getting my Korona Royal 5x7 working properly again.
    It is equipped with a locking rack and pinion to control movements which I really like, but the front extension doesn't lock anymore.
    I have found the following from the catalog showing the rack and pinion:
    Click image for larger version. 

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ID:	201349

    I have disassembled it and I think I know what is wrong and how to fix it, but I wanted to check with someone more experienced first.

    It seems that the ring that the outer teeth goes into to enable the lock is supposed to be attached to the bracket that is mounted to the camera and therefore wont rotate. Currently this ring is loose and can rotate freely. Should I just glue the ring to the bracket, or should I look into welding or some third option?

    Thank you.

  2. #2

    Join Date
    Aug 2013
    Location
    Chicago
    Posts
    1,706

    Re: Repair rack and pinion lock for extension rail

    If it's as you describe, it sounds like a job for soldering. If that's the case, I'd try to get the parts out and let a jeweler handle it.
    Thanks, but I'd rather just watch:
    Large format: http://flickr.com/michaeldarnton
    Mostly 35mm: http://flickr.com/mdarnton
    You want digital, color, etc?: http://www.flickr.com/photos/stradofear

  3. #3

    Join Date
    Aug 2000
    Location
    California
    Posts
    3,111

    Re: Repair rack and pinion lock for extension rail

    If you choose to solder it,use only silver solder.

  4. #4

    Join Date
    Jan 2020
    Location
    Denmark
    Posts
    4

    Re: Repair rack and pinion lock for extension rail

    Thanks, I'll take your advice and ask a local jeweler about it. What makes soldering a better solution than glue? I have a soldering iron myself that I use with lead solder, but I think soldering two pieces of metal together likes this would be difficult so the jeweler suggestion is really appreciated.

  5. #5

    Join Date
    Nov 2017
    Posts
    288

    Re: Repair rack and pinion lock for extension rail

    Soldering with a soldering iron as in making electrical joints is not very strong mechanically. Silver solder (high percentage silver) as used in brazing is much stronger but this is to be done with flame and flux. So it requires some skill and experience certainly with small parts. Welding means melting the parts to make the joint. And with small parts is very difficult (certainly if it are different materials) if you don't have the right equipment. And the risk of damaging the parts is great while for this use it will not be stronger than brazing.

    With solder you can make a very neat joint that will take almost no space. With glue this might not be possible if you need the strength. Some sorts of Loctite might work if you can get it fitting well enough en clean enough.
    Expert in non-working solutions.

  6. #6

    Join Date
    Mar 2019
    Location
    The Hague, Holland
    Posts
    63

    Re: Repair rack and pinion lock for extension rail

    When the wall anchors of our cast iron stair railing broke off, the local blacksmith soldered them back on with silver and gave me 5 y. guarantee when I worried if silver was strong enough for the purpose. That's 9 years ago now and they haven't failed yet. Silver is good for many things other than photography!
    Sales person: Mirrorless, the most important innovation in photography in decades!
    Me: I always knew my Sinar 8x10 was way ahead of its time.

  7. #7
    Tin Can's Avatar
    Join Date
    Dec 2011
    Posts
    13,473

    Re: Repair rack and pinion lock for extension rail

    sin eater

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