Retaining ring stuck on Horseman board

[hervedemers]

Hi everyone. I have recently bought a Nikkor 90mm f8 on eBay that came on a Horseman board (my camera uses Linhof type). In the past, I never had any issue unmounting a lens from a board to change it myself, with the proper lens wrench. This time, it's completely stuck. I've tried heating the ring with a hair dryer, forcing it really hard, without any success, except by adding awful marks on the ring itself. I'd love to have your advice on this

[Ari]

Hervé, I've sometimes found that by trying to turn the larger piece (lens board or shutter) and stabilizing the smaller piece (retaining ring), that things sometimes loosen up.
Maybe add some penetrating oil, but make sure it drips away from the shutter.
Good luck, let us know if you manage to get it off!

[hervedemers]

Hey Ari! Glad to see you here. Unfortunately, I've tried the freezer, tried holding the wrench to stabilize the retaining ring, it's still stuck. At this point, I'm afraid to put any liquid in there and thinking I should bring it to a repair shop. Do you know any good one you'd recommend in MTL for large format?

[Tin Can]

It must be glued

some did that, making us rely on experts

[hervedemers]

Thanks Tin! So you think my best option would be to find a repair shop that does LF lenses?

[Tin Can]

Most likely if you want

I never use expert repair and consider any mistake I make a valuable lesson

I prefer to buy the right tool, DIY

You have the right tool and obviously have tried very hard

solvent is next

Thanks Tin! So you think my best option would be to find a repair shop that does LF lenses?

[Jim Noel]

Unfortunately your wrench is too flexible to do the job as evidenced by the marks left when it came out of the grooves. It's too bad the best lens wrenches are no longer made. The best alternative today is one made of heavy steel with teeth appropriate for several rings, like a Rodenstock.

[John Layton]

Maybe start with boiling water...and try your retaining ring wrench - and if no go...try using something like a rubber jar-top gripper and do your best to use equal force around the circumference of the ring...maybe with the board itself mounted in a vice. Whatever you do, do not mount the ring in a vice...as then the forces would only squeeze the ring further and make things worse.

For stubborn filters, I sometimes find that an old length of electrical cord...wrapped around and gathered as a "handle" on one side - gives a good, strong, even grip. Not sure if a cord would fit the height of your ring, though.

If the boiling water does not work...maybe then go to a solvent of some sort - perhaps "PB-Blaster" like what I use to help undo rusted/corroded nuts and bolts on my car. If this does not work...you can take this outdoors - heat things up with a propane torch (not enough to get red hot!) - and apply some PB Blaster which, as the assembly cools, will get drawn further into the threads. Just watch yourself when you do this...as you may have a bit of a fire to deal with!

[hervedemers]

@Tin Can : What solvent would you recommend? I've tried adding a bit of my girlfriend's nail polish remover (which is mainly Acetone), but it did not move. Maybe I did not add enough, but I'm afraid it will go into the shutter.

@Jim : Thanks for the tip! I have one too, which I preferably use, but have you noticed the protruding metal ring on the back of the Horseman board around? I cannot get the teeth of that Rodenstock lens wrench inside the grooves like they should because of it. It's driving me crazy.

[hervedemers]

@John Layton : Thanks a lot John! When you say boiling water... you mean add drops of boiling water onto the outer threads where the ring is attached?