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  1. #1
    Greg Heath's Avatar
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    Mamiya RB67 leaf shutter pin prick hole- ideas?

    [FONT=Verdana,Arial,Helvetica][SIZE=2][FONT=Verdana,Arial,Helvetica][SIZE=2]Hi Everyone,

    I am scratching my head on this one. I have a 90mm RB67 lens that I have torn apart to rebuild. I have done 3 of these lenses and shutters with no problems. This new one has a 2 pinholes on one of the metal shutter leaves. Does anyone have any ideas other than tearing down the the shutter and swapping the leaf out, for patching the hole. A friend mentioned to me to use a pinprick of JB Weld, while compressing from the other side with wax paper.

    I thought of micro soldering to plug the hole.

    I also might patch it with that really thin self stick aluminum metal tape.

    I might even just use some thick super glue and quick bond agent to freeze it in place and then color it with a permanent black marker.

    Anyone have any other ideas, for this predicament?

    I do have another lens I can swap out the blade, but wanted to keep the shutter intact if I can.

    check out the photos. [/SIZE][/FONT][/SIZE][/FONT]
    Attached Thumbnails Attached Thumbnails photo(2)-2.jpg   photo(1)-2.jpg  

  2. #2
    Newt_on_Swings's Avatar
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    Man that looks like a tough fix. All the alternatives you have mentioned will build up too much thickness. You will still have to take it apart and sand it down really flat to not have friction on other blades or you might risk binding or even creating another pinhole. Friction would also affect speeds.

    I you get it apart, maybe a coat of paint across the entire surface of that blade, can patch it on both sides. The paint would be drawn into the hole. Durability would depend on paint type and thickness.

    Try finding another shutter or parts body to do a swap. Thats the sure way. Patches even if they do work, may fall apart and end up binding the shutter anyway.

  3. #3
    Worker 11811's Avatar
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    I think silver solder would do the trick. Get the silver good and hot so it flows into the hole then, after it cools and hardens, polish it smooth.
    Randy S.

    In girum imus nocte et consumimur igni.

    -----

    http://www.flickr.com/photos/randystankey/

  4. #4
    Mainecoonmaniac's Avatar
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    How about just leave it be? Does it add that much exposure in the grand scheme of things?

  5. #5

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    Quote Originally Posted by Greg Heath View Post
    [FONT=Verdana,Arial,Helvetica][SIZE=2][FONT=Verdana,Arial,Helvetica][SIZE=2]Hi Everyone,

    I am scratching my head on this one. I have a 90mm RB67 lens that I have torn apart to rebuild. I have done 3 of these lenses and shutters with no problems. This new one has a 2 pinholes on one of the metal shutter leaves. Does anyone have any ideas other than tearing down the the shutter and swapping the leaf out, for patching the hole. A friend mentioned to me to use a pinprick of JB Weld, while compressing from the other side with wax paper.

    I thought of micro soldering to plug the hole.

    I also might patch it with that really thin self stick aluminum metal tape.

    I might even just use some thick super glue and quick bond agent to freeze it in place and then color it with a permanent black marker.

    Anyone have any other ideas, for this predicament?

    I do have another lens I can swap out the blade, but wanted to keep the shutter intact if I can.

    check out the photos. [/SIZE][/FONT][/SIZE][/FONT]
    Wow, how on earth did that get there? Corrosion?

    The suggestion of opaque epoxy is pretty good, if you carefully scrape the repair flush with the leaf, it should work.

    I

  6. #6
    CGW
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    Seriously? Get a new shutter from a dead/diseased donor lens or just get another 90/3.8. Don't try Bondo, either.

  7. #7

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    If you really want to get fancy and complicated, you could plate it shut with copper, or rivet a tiny patch over it.

  8. #8
    Greg Heath's Avatar
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    I picked up two old 90mm lenses in hopes of getting at least one to work.

    The one with the operable shutter has the pinprick holes...and a slightly fungus'ed rear lens. I have already cured that with a 50/50 mix of Ammonia and Hydrogen Peroxide. I really didn't want to do a complete tear down piece by piece on the shutter, as I usually take out the lenses and the body and then soak the whole shutter in White Gas (Coleman lantern fuel), and then after a 15 minute soak, I turn on the Ultrasonic cleaner and let that run for 5 minutes. Usually whatever is causing the jam, is jarred loose, like dirt and grime and then I completely rinse it in fresh white gas, and then when it dries overnight I oil the spindles of the gears. That's about it. Runs great after that. I clean and reinstall the elements and rings and it runs like a champ.

    The other lens has a jammed shutter, so I will in fact tear it down and make it a parts shutter. Both lenses are old enough (1970-72) that they have Type "a" blades, so it should hopefully be a quick repair.

    This is not for my camera, it's for a friend. I want to make sure she has no problems, and the lens is in top shape. $40 for both lenses shipped. It has been fun. Thanks for the replies, and the laughs. It really is microsurgery. My guess is the holes were caused by corrosion. I removed the rust from the blade with a fiberglass pen. I love that thing..

    http://www.micro-tools.com/store/P-B...iberglass.aspx

    So it's either try to patch it or replace it. I might try both. replace it, and then do some practicing on what method works. The pin holes are at almost the base of the blade, so not sure about centrifugal "g"'s and it coming loose. If I can patch the blade, I will scrape off the rest of the paint around it, and then try a micro brush with the smallest amount of JB weld... These holes are tiny. I bet it will work. Worst case scenario I'm out $40. Best case scenario it works and I gain some knowledge about the Mamiya Shutter That and couple more gray hairs on my head. The JB weld is made for metal, but I will have to use the slightest mixed measure. plus it's black/gray colored. the rest of the paint that I will take off I can fix with dye, or my cheap alternative of a permanent black magic marker.

    I love a good challenge.


    Greg

  9. #9
    Greg Heath's Avatar
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    Quote Originally Posted by E. von Hoegh View Post
    Wow, how on earth did that get there? Corrosion?

    The suggestion of opaque epoxy is pretty good, if you carefully scrape the repair flush with the leaf, it should work.

    I

    I lived in the Adirondacks for 3 years (Plattsburgh).

  10. #10

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    Quote Originally Posted by Greg Heath View Post
    I lived in the Adirondacks for 3 years (Plattsburgh).
    I've lived in that area for 35 years, nothing like that has happened to any of my gear.

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