How to unscrew a stuck lens element...

[alex from holland]

Recently i bought myself a beautiful Dallmeyer 3a!
It's in beautiful original shape.
But there was one problem. All the lens elements were stuck
Also the soft focus function.

As i have tried this solution before on a Hermagis with a severe stuck rear element i gave it a try again, but now with this beauty.

All you need is a fitting piece of thin rubber, a screwdriver, a LITTLE hammer and a large hose clamp.
Cut the rubber just as wide as the clamp itself. Make sure you cut it a little shorter to keep the place open where the screw is.
This to make sure you get an equal pressure around the element.
Tighten the hose clamp slightly. There is no need to tighten it hard! When you tighten it to hard you might break the glass!!!
After that you take a small hammer and gently tap on the screw in the direction the element has to go loose.

Before this solution i have tried several options. I tried silicon spray several times over a few days, tried to unscrew it while wearing special rubber gloves.
Nothing worked. Now it came loose within 2 seconds.

I just wanted to share this with you.

http://upload.pbase.com/image/137439455/original.jpg


http://www.pbase.com/alex28/image/137439456.jpg


http://www.pbase.com/alex28/image/137439457.jpg

[E. von Hoegh]

Excellent trick!! Shock/vibration will often shift something that resists constant force.

For instance, it's vibration that loosens screws, not stress. Old time gunsmiths would use boiled oil as a screwlocking compound. I've used it myself, and it works just fine. Easier to remove than service-removeable loctite, too.

[Steven Tribe]

I don't think you are putting the glass at risk! It is things like pipe wrenches that do the damage. I have used this method too - hose clips. For difficult cases I have used the "senior" member of this class of tools - the auto piston ring compressor!
I have also discovered that two people is often a very good solution if you don't have a system to clamp the barrel.
Left and right hands don't achieve torsion by themselves.

[cdholden]

Alex,
You mention the use of silicon spray. Here in the US, we have this amazing stuff called PB Blaster. It is a penetrating oil, but it doesn't get everywhere and make a mess like Liquid Wrench, WD-40, and others like it. It does very well with breaking corroded bolts in automotive use and I have even had good luck using it on rusted door frames (door rusted shut) and similar problem as yours on a couple of smaller lenses.
If using it alone gets no results, heat up the lens where you have applied it (maybe with a toothpick, fine tip brush or hypodermic needle). A hair dryer works well for this.
While you can find it in automotive parts stores, it works wonders in all sorts of situations. It is a solvent and it is flammable.
I hope this might be able to help you in a future project.
Chris

[Nasir]

Hey Alex,

I'm in the same situation with a stuck rear element on a Dallmeyer 3B. I tried this method but the whole rear group of the lens turns. I've tried to hold it firm with a gator grip rubber strap but it still turns when I tap the jubilee clip. Any suggestions? Should I try clamping in a vice? Thanks.

[Jac@stafford.net]

Kroil (http://www.kanolabs.com/google/?gclid=CjwKCAjwwtTmBRBqEiwA-b6c_4QhX_1l40Dl3TYmPIrxfmoMlp300hoeZPu4l3anLR4oT2F4MDP9XRoC1PUQAvD_BwE) works well, too.

[alex from holland]

But what’s the effect on the balsam when it gets in contact with the side of the glass elements?

[Jac@stafford.net]

But what’s the effect on the balsam when it gets in contact with the side of the glass elements?

Personally, I don't care if there is an effect. If we cannot separate the lens unit it is likely no good.

[Steven Tribe]

Hey Alex,

I'm in the same situation with a stuck rear element on a Dallmeyer 3B. I tried this method but the whole rear group of the lens turns. I've tried to hold it firm with a gator grip rubber strap but it still turns when I tap the jubilee clip. Any suggestions? Should I try clamping in a vice? Thanks.

NO - you will just create 2 opposite flat areas that worsen the situation! But you could use a vice if you had formed wooden pieces in between the curved brass and the flat metal vice jaws.
"Tap" is perhaps too gentle an expression - I would say "strike"! Be brave!

I have not seen any damage from the use of lubricants/zylene. To be frank, most achromats I have seen on aged Petzvals could do with having their balsam redone!

[Eric Woodbury]

My repair guy couldn't remove the forward element of my 360mm to get to the shutter. He wrapped the front element with double-sided tape so he could use his hands and get a firm grip.