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Removing stripped screws from Nikkormat lens mount
Old 10-10-2019   #1
George Mann
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Removing stripped screws from Nikkormat lens mount

Hi. I have a Nikkormat that has stripped screw heads in its lens mount. I want to remove it to fix the ASA lock, and possible clean the resistor ring (difficult?).

Should I just tap them out and replace them, or do you have other things to try first?
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Old 10-10-2019   #2
peterm1
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You can buy screw removers but I have never seen them in sizes for small screws like the ones, I am sure are in your lens mount. One thought though, is that you might try to ask a specialist supplier such as a jewellers' supply company if they can help - they might have or be able to suggest something.

A better option would probably be trying first is to see if you can recut the screw head /screw slot in situ. Again you could go to a jewellers supply company and buy a chisel graver of the sort used by this guy in the video (jump to about 6.00 minutes in). They are the ones used with a hammer not the sort designed to be pushed by hand and are sold singly, are not too expensive from memory and would work I am sure as they are made from hardened steel. Just recut a slot and use a normal driver that fits that slot to unscrew it. If necessary regrind an existing screw driver specifically to fit the new slot closely.

https://www.youtube.com/watch?v=BkhWh19fTG4&t=2s

Another alternative if you have a Dremel tool is to use a small Dremel burr to recut the slot instead of a metal graver. There is a reference in the following thread to a guy doing exactly that for a small camera screw. Dremels are great - I love them and would say this solution is probably your best bet assuming you have a steady hand and good eyes. Also assuming you already have a Dremel or can borrow one. Unless you want to buy one of course. BTW if the existing slot is phillips head you can still turn this into a normal screw slot for the purpose of removal of the thing.

https://www.ifixit.com/Answers/View/...l+camera+screw

Also if the screw is tight (and it may be given the screw was stripped) you could try a rapid heating / cooling cycle to break the lock. Use the tip of a small soldering iron (the sort used for electronic PCBs) and hold it to the head of the screw to heat it. Then use a blast of cold air (a giotto rocket blower or canned air could work) to rapidly cool it again. Then try to unscrew it. On the chance that thread lock has been used you may also wish to first try using some acetone to make sure the screw will unlock once the head slot has been recut.
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Old 10-10-2019   #3
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You could buy a drill bit of the correct size to drill the screw out, but in left-handed orientation. That would act similar to a 'screw extractor' and if it doesn't jar it loose, you're on your way to drilling it out which would be the next step anyway. They should be available at McMaster-Carr
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Old 10-10-2019   #4
George Mann
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Thanks for all of the tips guys. Of course, I had already thought of some of this to try.

The problem is, whoever damaged them really cemented them back into place.
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Old 10-10-2019   #5
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Quote:
Originally Posted by George Mann View Post
Thanks for all of the tips guys. Of course, I had already thought of some of this to try.

The problem is, whoever damaged them really cemented them back into place.

Another possibility then may be to use a slightly larger drill - the same diameter as the counter sink of the head. Carefully drill the head off leaving the threaded screw shank intact. (This assumes that the mounting plate / ring is not itself threaded but just has a hole for the screw and a countersink for the head). The mount ring should then lift off over the shank - leaving the shank in the body of the camera. Then you could try using needle nosed pliers to grip the shank and twist. If its still stuck after that and acetone etc does not work, I think you might be limited to drilling and tapping a new hole.

Some ideas here but it sounds as though you have tried most of these. https://www.youtube.com/watch?v=gt1vTfGJNp4

EDIT: A final option occurs to me. If you can get hold of a small sharp, hardened steel scribe or punch or graver (of the sort I mentioned below) you can try using it not to reform the slot but rather use it with a small hammer to turn the screw directly by tapping it into the face of the screw at an angle. This requires holding the point of the scribe etc at a low angle to the face of the screw and as close to a tangent as possible. Tapping the tool with a hammer in an anti clockwise direction can cause the screw to begin rotating.
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Old 10-10-2019   #6
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Quote:
Originally Posted by peterm1 View Post

EDIT: A final option occurs to me. If you can get hold of a small sharp, hardened steel scribe or punch or graver (of the sort I mentioned below) you can try using it not to reform the slot but rather use it with a small hammer to turn the screw directly by tapping it into the face of the screw at an angle. This requires holding the point of the scribe etc at a low angle to the face of the screw and as close to a tangent as possible. Tapping the tool with a hammer in an anti clockwise direction can cause the screw to begin rotating.
Well, 2 of them may come out without trouble. The other 3 feel like they have cement in the threads.

I thought about drilling their heads off, and removing whats left with vice grips once the mount was removed.
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Old 10-10-2019   #7
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Quote:
Originally Posted by George Mann View Post
Well, 2 of them may come out without trouble. The other 3 feel like they have cement in the threads.

I thought about drilling their heads off, and removing whats left with vice grips once the mount was removed.

I kind of think that if someone cemented the screws in with something like epoxy then you are screwed. hahahaha See what I did there (sorry, they do say that word play is the least creditable kind of wit).

But seriously I am not sure how you could deal with that other than quite extreme heat and that brings other obvious problems and issues. 200 degrees F seems to be the magic number. But I think my inclination in that case would be to (a) remove the other screws that do not need the treatment then (b) drill the screw heads off the jammed ones, then (c) remove the mounting plate and only then try more extreme measures to get the screw shanks out. As a very last resort it should be possible to drill and tap entirely new holes in new locations and use those when remounting the lens mount ring to replace any screw holes that are now unusable.

This link may give you some ideas for dealing with various kinds of cement.

https://www.permabond.com/2014/09/11...ger-adhesives/

If its epoxy then this may give some ideas - paint remover is an option it seems but getting that into the threads raises another issue.

https://watsoncoatings.com/quick-fix...-remove-epoxy/
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Old 10-10-2019   #8
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I think your idea of drilling the heads off them, removing the mount and gripping what is protruding with vise grips, is reasonably sound. Unless they have been put in with high strength loctite or similar I can't see why they wouldn't move. Good luck which ever way you try to do it.
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Old 10-11-2019   #9
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Heat the screws then when they cool, use acetone or MEK to further soften any adhesive. I wouldn't use a hammer for a punch, use a spring pin punch instead. You can get them cheap at bargain tool stores like harbor freight. Grind the tip as you need to make a custom chisel point. Good luck.
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Old 10-11-2019   #10
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Probably epoxy or superglue. Maybe a soldering iron held to them will soften the glues.
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Old 10-11-2019   #11
George Mann
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I think I have enough suggestions to try again once I finish the test roll of film in it.

Thanks guys.
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