lens cells stick in shutter - any tips?

[koh303]

I have a lens which i bought for the shutter. But the cells are locked in place.
At least on the rear cell i can see what appears to be some glue/locktite type smear around the edges of the threads.

Is there a simple way to get this off the shutter without breaking the shutter?

Not worried about the lens so much.

[Robert A. Zeichner]

Depending on what type of glue/locktite was used, this may require some heat and/or solvent to soften. I would first try taking a small sheet of innertube material or one of those rubber jar lid openers and use that to attemp to loosen. More often than not, it's a question of getting a good grip. If that fails, you might put a drop of acetone on the area where the threads meet the shutter. Let capillary action do the work and don't flood the area with solvent as this will dissolve paint. Wait a bit and try the rubber sheet again. It may take a few tries, but eventually, the acetone should reach the glue and soften it.

[koh303]

will try - thanks!

[Oren Grad]

I would first try taking a small sheet of innertube material or one of those rubber jar lid openers and use that to attemp to loosen. More often than not, it's a question of getting a good grip.

In a similar vein, I once needed a rubber strap wrench to free a cell that was frozen in a barrel mount. Took a fair amount of tugging and fussing, but in the end it came free, and without marring the finish or otherwise damaging anything. Same idea as the inner tube or jar gripper, but sometimes having it in the form of a strap wrench allows a firmer grip and a bit of leverage.

[Will S]

I'll second what Oren says. Once had to use a oil filter strap wrench and apply a really large amount of force to a lens to get it to loosen. That was a barrel so I wasn't so concerned with breaking it, but it took a lot more coaxing than I would have believed.

[koh303]

In a similar vein, I once needed a rubber strap wrench to free a cell that was frozen in a barrel mount. Took a fair amount of tugging and fussing, but in the end it came free, and without marring the finish or otherwise damaging anything. Same idea as the inner tube or jar gripper, but sometimes having it in the form of a strap wrench allows a firmer grip and a bit of leverage.

Unfortunately, the PO has pretty much "marred" this lens to a point where UG definition would no longer apply, so i am not worried about that so much...
Just trying to save the shutter...

[jnantz]

have you tried the freezer yet ?

[EdSawyer]

heat gun would be a good thing to try. In addition to a strap wrench or two at the same time.

[Tracy Storer]

Be careful with your grip......grab one cell and the shutter at a time, twisting the front cell against the rear cell will put rotational shear forces on the shutter, and could harm it. Strap wrenches are great for barrel lenses, but the controls on the shutter may get in the way. Sometimes it takes a drop or two of penetrating oil at the joint per day, for a couple days, before things yield. In extremely tough cases with one cell out and the other cell stuck, I have "snuck through" the barrel or shutter to get a drop of oil on the threads from the inside, being very careful not to use too much.(rear cells are often too close to the aperture to do this)

[koh303]

Update:
Acetone loosened the rear cell enough to remove with hand force.
Front cell has been immersed for hours, and no such luck yet.

I will try Tracy's suggestion now.

[Tin Can]

Tracy has good advice.

It can take months or a year to get stuck farm tractor rings loose in an antique. One trick is a telephone pole through the rear wheel and jacked up for constant pressure. The rings were loose when the wheels came back to earth. I knew a guy that did this all the time.

Maybe there is a way to apply constant pressure over time, of course with a solvent oil present.

[koh303]

unfortunately, as someone above posted, there is nothing really to grip as far as the shutter is concerned, without damaging it.

Also unfrtunately, this is a Copal 3s, and there is no way to get oil or anything else into the threads through the inside path of the shutter without getting it all over the place. I already have at least some acetone inside the shutter, despite having used it VERY sparingly... There is just not enough clearance and the cell has a wide, square bottom profile which extends all the way to the edge of the blades.

In the past i have had good luck with mounted a shutter on a lens board super tightly and using the board as extra leverage against the cell. No luck with this one, as it slips all the time. Tomorrow i will try something else - i have a front mounting flange with drill holes - i will mount it to my work bench, load the shutter in and then will have all the pressure i need. If the screws hold, the cell will either come out, or i will break the collar. the lens is already so badly damaged (externally only), from the PO's attemtps, coupled with my barn house skills, that i am not so much worried about it at this point (though was hoping to save it somehow...).
If the collar breaks, i will just hack the cell out and crack it with a vise grip. A sad end to a stupidly built lens. Who and why would locktite a very simple, and not aerial lens cell to the shutter? Maybe it was such a poor design they wanted to make sure you use it and not swap out for the shutter... who knows.

Tomorrow will tell.

[stiganas]

Thank you, this topic was excellent. I have a 300mm Zena Tessar with a stuck mounting flange. I applied a little bit of heat from a hair dryer and, et voilà, the flange came out nicely, without any kind of force.129772

No glue was used on this one. It was just very tight (years ago).


Depending on what type of glue/locktite was used, this may require some heat and/or solvent to soften. I would first try taking a small sheet of innertube material or one of those rubber jar lid openers and use that to attemp to loosen. More often than not, it's a question of getting a good grip. If that fails, you might put a drop of acetone on the area where the threads meet the shutter. Let capillary action do the work and don't flood the area with solvent as this will dissolve paint. Wait a bit and try the rubber sheet again. It may take a few tries, but eventually, the acetone should reach the glue and soften it.

[Eric Woodbury]

I had a stuck group in a shutter years ago. My lens mechanic wrapped his hands in double stick tape so he could get a non-slip grip. That did it.

Good luck adventurers.

[koh303]

Update:

I am leaving for a couple of days, and just before walking out the office i decided to give this another whirl. The other day i had a 300mm which was slightly stuck to the shutter, but there, i had plenty of lens to grab. I put the shutter without the rear cell on the soft carpet, and used the soft rubber soles of my shows as grip against the face of the shutter, just where i had nothing protruding. That worked, and so today, having already given up on this lens stuck in shutter, as i have already destroyed the lens even more then the PO did, and had no hope of using the shutter or the lens at this stage, i decided to try the shoe trick again. With LOTS of force, i used a metal bar wedged inside 2 grooves i had cut out in the soft aluminum front cell sleeve, and got it to move about 1cm. Very much encouraged by this i tried again, but now had nowhere to put my shoes without bending any lever, though with some give and take i managed to do that.

Turns out there was some kind of glue, at the base of the lens barrel where it comes into contact with the face of the shutter, and some type of goop all the way along the VERY long threads. This is by far the longest threaded cell i have ever seen. In fact it was twice as long as the 300 i had pulled out yesterday.

Amazingly enough, after being able to pull this off, and with my new sense of confidence, i put all the elements back into the front cell barrel, despite all the cuts and drills, everything fell into place perfectly, cleanly, and all rings screwed right back. I doubt this is an optical marvel any more, but i am sure this lens works (will test when i am back), albeit very, very ugly. It was kind of a useless lens to start out with.

So, now i have a free brand new (less some aluminum and acetone debris) Copal 3S shutter for my Astragon 360mm f6.3!

Will update with photos when i am back.