retaining ring too tight

[kunlun121]

Recently I bought a really nice Grandagon 155 f/6.3. It's on a Technika board and I want to move it to a Sinar board. The retaining ring fixing the lens to the board is so ridiculously tight that I can't begin to loosen it. I am using the tool pictured here.



When the metal of the tool starts to flex I stop. Don't want to break it.

What kind of tool allows you to put more force on the ring?

[Ulophot]

I am not a mechanistically inclined person, so don't necessarily take this advice. but I wonder if either a touch of thin lubricant or using something like a small tacking or soldering iron briefly to heat the retaining ring might loosen it up.

[domaz]

Someone may have put thread locker on the threads or you have a bit of corrosion going on. Using some sort of anti-seize lubricant in small quantities might work. If it's mounted on a lensboard you could put the lensboard in a bench vise to get more leverage.

[kunlun121]

I am hesitant to apply liquids to the thread as I'm worried it may enter the cells. Same for applying heat - not sure it's low risk enough for me to try. Maybe I should have a professional look at it.

[jim_jm]

If this is for the lock ring on the back side of the lens board, I'd first try a bit of anti-seize or break-free lubricant on the outer edge of the ring, where it contacts the board. Several drops shouldn't get into the lens. Let it soak in for awhile and try again. If that doesn't work, a proper lens spanner will allow for more leverage. Sometimes these rings can get really tight over several decades.

[rfesk]

I had that problem. I purchased one that has pins that fit the slots in the ring. Was able to apply my efforts very close to the ring. Very stressful on a new (to me) lens that costs hundreds.

[domaz]

If the lens is attached to the lensboard I often find moving the lensboard around while keeping the lens and retaining ring in place is more effective than anything else. Removing a stuck retaining ring on a lens without a lensboard is very tricky.

[MartyNL]

I had a similar problem with a Sinaron 210mm on a sinar board and gave it to the Sinar specialist at the time. They separed the shutter and lens board but only at the expense of shearing the copal shutter threads completely off. We agreed to go halves on a new shutter.

What I'm trying to say, is that it might not be possible but I hope you have better luck than I did.

I quite like the idea of applying localised heat via a tacking iron, hadn't thought of that...

[paulbarden]

Can you see any signs of a matte black paint-like substance in the vicinity of the ring? I have dealt with a number of shutters, and I sometimes find that a previous technician has used a matte black lacquer to "lock" a ring in place. If you see any of this, it's worth trying to soften it with the careful application of Acetone to the ring area, let it sit a couple minutes, reapply, and then try your spanner. I use tweezers, dipped into acetone, to pick up a small amount and then I can carefully place it where I want.

[kunlun121]

Thank you for all these great suggestions. Last night I ordered a proper spanner wrench like the one @jim_jim suggested. If I replace the horizontal rods with much longer ones I’ll be able to exert much more torque with ease. Meanwhile I’ll examine the ring’s edges for loctite or other gunk. That would really be criminally negligent, hopefully I’m spared that ordeal. In another thead here I found people suggested the miracle substance named WD-40, which I may give a try if the ring has not been glued. As a last resort a dremel may be able to save the thread of the shutter if I cut through the lens board. I’d really hate to lose this Prontor Professional.