Unscrewing super-old lens cells

[Yourix]

Hello everyone

I just bought a 12x10 Dallmeyer Rapid-Rectilinear. By it's serial number I can tell It is from 1883... So a good 140 years old.
It is in very good shape except it is really dirty inside. Ove the years the dust found it's way trough the waterhouse stop slit.

To clean it completely I'll have to unscrew the front and rear cells but the thing seems to be damn tight ! Do you have any tip to loosen it ? On "modern" lens I usually use some aceton or varnish nail remover to soften the threadlocker that is usualy used, but on this old lens I suspect the use of something different, maybe some kind of cement ?
Any hint welcome !

Thank you

[diversey]

Please see the link below, I have used this method to unscrew a lens before. This method is very effective!

https://www.largeformatphotography.i...t=Unscrew+lens

[Greg]

Please see the link below, I have used this method to unscrew a lens before. This method is very effective!

https://www.largeformatphotography.i...t=Unscrew+lens

Definitely works. I've done this successfully on two lenses. I used three screw clamps side by side and a bar of metal that spanned across the three tightening "screws". Preferred to use a medium sized hammer and hitting it very lightly. The ring on one lens would not budge so I put only two or three drops of penetrating oil, tapped it a few times very, very lightly and let it sit for a few days. Had to tap the clamps only once lightly to come free free. The penetrating oil never penetrated farther than the threads.

[Greg]

Definitely works. I've done this successfully on two lenses. I used three screw clamps side by side and a bar of metal that spanned across the three tightening "screws". Preferred to use a medium sized hammer and hitting it very lightly. The ring on one lens would not budge so I put only two or three drops of penetrating oil, tapped it a few times very, very lightly and let it sit for a few days. Had to tap the clamps only once lightly to come free free. The penetrating oil never penetrated farther than the threads.

OP of the above post: The penetrating oil wasn't WD40. I was given it by an automobile restorer. He called it "Panther Piss"... I'm sure that was a slang name for it. He closed shop many years ago so I have no idea of its name brand.

[domaz]

If you use penetrating oil remember that most of them smell terrible. Might be good on a sunny day when you can keep the lens outside for a while to let things air out.

[Mark Sampson]

"Kroil" is the best penetrating oil. "PB Blaster" and "Liquid Wrench" also work well. A little goes a long way, and give it time to work.

[Havoc]

Another thing that sometimes helped me was putting the front of the lens on a piece of rubber, flat on the desk. And then turn the rest of the lens while pressing on it from above.

[j.e.simmons]

I've used PB Blaster with good results. First, though, I'd try pressing the element you want to remove into the side of an automobile tire and turning. Sometimes that works.

[Yourix]

Excellent !
Thank you for those tips, I'll give it a try...
All the penetrating oils brands you mention are unknown to me (except wd40) as I'm in France, but we have equivalent.

But first I think I'll try to shoot one or two sheets of film before cleaning, just to see the before/after effect.

[Tracy Storer]

I use opposing strap wrenches (like you can buy at the auto parts store for oil filters). If the parts don't move, I will put a drop of light penetrating oil on the seam and give it a day to hopefully "wick in" ten try again. Sometimes it takes a couple applications of oil and several days.
CAUTION: Make sure you use the strap wrenches on well supported sections of the barrel so the lever action of the handle doesn't dent/deform the sometimes thin walled tube of the barrel.