disassembly of a prontor shutter (from a folder)

Discussion in 'Camera Building, Repairs & Modification' started by pellicle, Oct 5, 2008.

  1. pellicle

    pellicle Member

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    Hi

    I have been pondering repairing a prontor shutter in an old folder which sticks on speeds below 25th. I've read on some forums that it can perhaps be removed from the camera, the lens elements taken off and then soaked in some lighter fluid to dissolve the gunked up lubricants.

    I've managed to get the front off (and the distance scale) without problems, however I've come unstuck at this point

    [​IMG]

    I had thought that this metal section should simply unscrew, but it doesn't (simply, it seems to want to fight about it). By the way, thats a magnet tool there, not a broken screwdriver (I'm not that rough) :D.

    [​IMG]

    In fact you can see a small mark that I put on it from my attempt. Now, even though I (thought) I was careful I've observed that I've put small dent in this ring (you can just see it in the image in the exact left hand side of the ring (the "focus" marker is pointing to it). I only noticed this upon taking and posting these images.

    So, my questions are:

    1. how can I best unscrew this to expose my shutter
    2. what's the best strategy for straightening that ring?

    I was thinking of shaping some doweling wood and using that with a small hammer to tap it straight (hoping that the wood will damage the thread).

    So, should I continue with this, or just get a whole new "unit" off ebay?
    Thanks
     
  2. bnstein

    bnstein Member

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    The wooden dowel trick works quite nicely. Dont get another unit yet: milk this one for what its worth!

    Sometimes getting the front dial off is totally unobvious. I suspect you still need to unscrew one more bit, the bit youve been fighting. See http://www.rolandandcaroline.co.uk/repair/prontors1.html. Also the pages around http://pheugo.com/cameras/index.php?page=klio are worth a look.
    I had one where all I had to do was lift the shutter dial and it all came off.

    What camera was it from? Sometimes specific instructions are available.
     
  3. pellicle

    pellicle Member

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    Hi

    you know, I came here to report that I was ready to declare it a lost cause.

    Thanks for the encouragement / attitude re-adjustment. :smile:

    Anyway, I've gone over it a few times with the wooden dowel and the rim sat in a bit of pine cut to a V and now its looking good.

    While I can't see any 'out of plumb' areas but it must be out by a quarter of a smidgen somewhere, as I can just get it on (and to tighten down) with the help of a "rubber strap" wrapped around the front element to give me purchase. I know its not cross threaded as when I take it off the thread looks perfect.

    Thanks for the links ... I'll have a go more.

    do you know what makes me cry?

    I just put a few drops of lighter fluid around the rim there to loosen up the core and it must have seeped into the mechanism and done the trick cos the bloody shutter is now working perfectly now.

    Now my next trick will be getting it back onto the camera as when I tried to refit lastnight I found that the rear collar sticks up past the bellows preventing me from tightening the collar up. I can't sus out how to get this tightened back without it then pinching the bellows at the end. (Pictures will be posted if people don't get this description.

    The camera is a Bessa I
     
  4. paul ron

    paul ron Member

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    If you file 2 small notches in the rim of that piece, then using a straight edge accross, you'll be able to unscrew it.
     
  5. jsfyfe

    jsfyfe Member

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  6. pellicle

    pellicle Member

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    sweet :smile:

    thanks folks ... I'll try both, notch first (zero dollar solution) tool second ;-)
     
  7. sausage100uk

    sausage100uk Member

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    beware of the scenario I had with my Yashica LM, I lighter-fluid soaked the shutter and it worked, until I got it back in the camera grrrrrrrrrrrrrrrrrrrrrrrr. I read on some forums that lighter fluid will just spread lube everywhere and after a few days it will gum up again. I resorted to electrical contact cleaner (make sure its ok to use on rubber) and it worked like a dream....
     
  8. pellicle

    pellicle Member

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    Sausage

    good point!

    thanks
     
  9. Andrew Moxom

    Andrew Moxom Member

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    Try a neoprene jar lid remover. Place the lens/shutter lens down onto this and then while holding the shutter body, uncscrew it. Anything that puts stress against the thread by pinching will jam it tight... Hence your dent!