Help!
I have read on many places about how old aluminium barrels get their threads cold-welded by time and humidity, and about the risks involved, if you try to disassemble them by force.
Even S.K. Grimes site advises that the risk is yours, if you send them a lens in such conditions.
Anyway, i just got an american made Goerz Dagor 6.5" f6.8, on an old dial-set. I got it for a very reasonable price, but the lenses are very dirty, from evaporated oil and possibly from a small fungal infection.
In the auction it was clearly stated that the vendor could not remove the optics for cleaning, because the front and rear cells were stuck in place. He optimistically affirmed that "with the right tools" it would be possible to remove the cells and have them cleaned. Unfortunately when i had the lens in my hands, i found that the shutter works well only with fast speeds (now it's stuck open after i tried one of the slow positions... but of course it's nothing to worry about) and that the aluminium barrel of the back cell was badly scratched after an unsuccessful attempt at removing it from the shutter.
Of course the scratch is not a problem in itself, after all the paint has peeled off in part, so a good sansing and a new black paint should restore the original appearance.
What's a problem is that there is evidence that an effort, strong enough to leave a dent, couldn't remove the cell from the shutter.
What to do now?
The most dangerous thing is that the "glasses" can't be removed from the outside, probably the retaining rings are accessible from the inside, and not viceversa. This means that if you apply a lot of force, and the aliminium barrel collapse, the lenses would likely be destroyed, or at least badly damaged.
The lenses are uncoated, so i think it should be possible to safely apply one of those sprays that are used to help remove old bolts.
Do you have any suggestion.
Do the use of a hot airgun be allowed, or the shutter would be too badly affected?
If you have any trick or simply some suggestion to follow, i'd be very grateful.
Fortunately SK Grimes people write on their site that they never broke a single lens, advising at the same time that you take a risk, probably implying that fortune doesn't last forever :-)
cheers
CJ
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