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  1. #1

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    Stripped copal retaining thread

    I received a pretty Nikon 65mm sw (for use w/rollfilm back) today that was in great condition, except for a pretty beatup Wista lensboard, took it off the board it came with to put it in a new chinese recessed board and despite having done this many times I managed to muck it up, apply too much force, and stripped(wrong word?) the threads on the copal shutter as well as the retaining ring.

    Is there any easy (cheap) way to fix this? Maybe take it to a local machinist/lathe? I can't be the first one to make this stupid mistake.

    Sorry if this is a common question, tried to search but only got results of people trying to fix old wooden cameras with stripped screws... learned the neat toothpick fix for that scenario but nothing in this one.

  2. #2
    Jon Shiu's Avatar
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    Could it be that the threads on the back of the shutter are still usable and you just need a new retaining ring?

    Jon
    Mendocino Coast Black and White Photography: www.jonshiu.com

  3. #3

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    Nope I hamhandedly forced it and upon inspection both the ring and copal 0 jave their threads smashed. Tried putting the ring on my 90sw's copal 0 and ut didnt work, and the 90's ring couldnt go on the shutter in question.

  4. #4
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    I would get a couple of new retaining rings and try to carefully use one as a die to realign the thread.

  5. #5

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    by realign does that mean just forcing the new retaining ring onto the shutter and using it to "cut" / clear the threads of the shutter? Sorry not the most mechanically inclined...

    edit: so after some reading the basics of thread repair (for auto restoration) it seems I want a thread chaser or die? However given the relatively large diameter and small pitch of these delicate threads finding something to straighten the threads out would be pretty difficult, hence your suggestion to just buy a few retaining rings and use them to "recut" the threads on the copal shutter?
    Last edited by watanabe`; 08-20-2011 at 10:20 PM. Click to view previous post history.

  6. #6

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    The Copal 0 shutter uses 32.5mm x 0.5mm mounting thread. The threads on the shutter body and the retaining ring are relatively soft aluminum.

    You cannot reform the male thread on the shutter by forcing a new ring onto it. The thread of the new ring is far too soft. That will only ruin the thread of the ring.

    I suggest emailing SK Grimes for advice. That is one of the few places with experience in such matters and it might have a chasing die or a lathe setup for holding the shutter body as the threads are refreshed.

    You won’t find such a special tool or a shop with that type of special experience in SE Michigan and any machine shop that could do the work would have to charge you far more than the entire lens and shutter together are worth.

    Further tampering will only make matters worse. By discussing this with SKG you’ll have the best advice and possibly, a practical solution.

    http://www.skgrimes.com/home

  7. #7
    Jon Shiu's Avatar
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    Quote Originally Posted by Ian C View Post
    The Copal 0 shutter uses 32.5mm x 0.5mm mounting thread. The threads on the shutter body and the retaining ring are relatively soft aluminum.
    Usually the shutter body is steel and the ring is aluminum.

    Jon
    Mendocino Coast Black and White Photography: www.jonshiu.com

  8. #8

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    I've used dental probes with a sharpened edge/point for this sort of "adjustment"
    Carving knives(wood) can work very well too. A cheap set the good ones are too good(?). I'll use the non-sharpened edge to do the work
    they have corners that work very well.
    Heavily sedated for your protection.

  9. #9
    Leigh B's Avatar
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    Turning a 0.5mm thread requires specialized tooling that most machine shops won't have.

    I suggest SK Grimes, as mentioned previously. www.skgrimes.com

    The proper lens wrench/spanner is available from B&H for $22: http://www.bhphotovideo.com/c/produc...ns_Wrench.html

    - Leigh

  10. #10

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    Thanks for all the advice will give sk a call.

    Also, I have one of the square metal lenswrench stamped spanners, however the lens in question had one of those small set screws to prevent it from spinning in the lens board. When I received it thelens had some wobble on the board so I took it off. Found 2 grooves in the hole on the board that looked like one of them would hold the screw so realigned the front element with that and started cranking on the ring when after a turn it wouldn't go any further. Stupidly thought I was pulling the lens into it's proper place when in fact I was just pulling the threads out. Let that be a lesson to you that you probably already knew: don't force anything camera related when it won't move.

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