brass lens front stuck

[Hollis]

Hey all, I have a large petzval brass lens, unmarked, that I am trying to get the front (or rear) group off so that I can have it mounted into a combo flange/lensboard (all one piece). It appears that someone has used a liberal amount of polish on it at some point in its recent life and it has locked the threads tight and I cant get them off. Does anyone have any suggestions as to how to get these to turn?


Hollis

[vinny]

Something like this will help.
http://www.cookmatesouthwest.co.uk/a...het_Strap.html
Or saw the lens board down the middle on 2 sides with a coping saw and split it in half.

[John Schneider]

Two small strap wrenches should make quick work of it.

[Gordon Moat]

Sorbothane pad against which you can apply leverage by twisting, without causing any crushing force nor pressure on the barrel. You can find something similar in an art store in the screen printing supplies, in the form of a braying pad, which is a type of rubbery pad.

Ciao!

Gordon Moat Photography

[W K Longcor]

Since you have some "polish" goop that is down in the threads, you might need more than a strap wrench will do. Stop at an auto spply store for a spray can of "PB BLASTER" -- DO NOT spray it on the lens. (The stuff is great , but SMELLS really bad)Spray some in a can or small jar. Use a small brush to apply right on the thread area. Allow several hours to soak in. Apply several times. Then try the strap wrench. As long as the threads are not crossed -- it should come right off. Unless it is aluminum against aluminum -- then you are out of luck.

[Hollis]

ill give it a try. No, it is brass on brass. I tried a little WD 40 in the threads over the weekend but that didn't work.

H.

[Chauncey Walden]

I've had real good luck with running a drop of Break Free CLP around the joint followed by gentle tapping all the way around with the butt end of a plastic screwdriver. You might have to repeat over the course of a couple of days but it usually only takes hand pressure to unscrew it after that. The tapping is the key.

[Keith Pitman]

I have had good luck separating stuck components by placing the lens in the freezer for a half hour, then carefully heating one of the elements. Use something dry like a heating pad or hot towel for heat. The freezing/heating causes one side to contract and the other to expand.

[goamules]

I had trouble getting my brass Vitax apart for cleaning. CLP Breakfree is great, let it soak in for a few hours, add more, etc. The problem was gripping the 3 inch diameter lens. It just kept slipping in our hands. We also needed more leverage or torque.

So what worked for me: Cut two semicircles in the edges of two 2x4s or similar small boards, slightly larger than the lens body. You're basically going to make a hand vise. Line the cuts with inner tube to protect the brass. You want the cut to fit snug, but with a little gap between the boards so you can grip them together tightly. Make another set, of thinner wood to fit just the element section. Get a partner to hold the barrel tight with one set, as you grip the other and unscrew.

[Skorzen]

I have had good luck separating stuck components by placing the lens in the freezer for a half hour, then carefully heating one of the elements. Use something dry like a heating pad or hot towel for heat. The freezing/heating causes one side to contract and the other to expand.

This scares me, I don't know just how sensitive the glass in lenses is, but I know glass does not like rapid temperature changes.