Damaged aperture - is it fixable

[Randy]

As usual, I just can't leave well enough alone.

I purchased a little Velostigmat Series II 9 1/2" lens with the softening ring. Lens is in barrel. The aperture, while working, was a tad stiff - as is the case with some of these 100 year old lenses. I was worried that I might damage a blade during use, so I decided to try to damage a blade (or two) by trying to clean it up - success!
I popped the little brass post off the end of two of the blades - *&#!
I tried to epoxy them back on but it would not hold.

I guess I could fabricate two new blades out of a thin plastic or film, and perhaps two little posts from Teflon or some such material, but securely affixing them to the aperture blade...?...I have no idea. And this thing has 20 blades - I can't afford to damage any more.

Anyone found a suitable fix (other than not damaging it in the first place)?

In the meantime, so I can get some use out of the lens, I have made a few (f/5.6, 8, and 11) water-house stops out of black paper, but I have to unscrew the front cells in order to change f/stops - which sucks.

[Randy]

It only took 6 minutes to get the first entirely unhelpful condescending comment of this thread - thank you internets!

[Bernice Loui]

The pins at the end of an aperture blade is often swaged on in much the same way as a rivet. Over decades of being moved, the joint can work loose. It is possible to replace the pin or try re-swaging the pin back on with a very tiny amount of epoxy to help the pin to blade joint stay put. Check the condition of the hole in the aperture blade, it could be deformed or enlarged (typically flared-stretched out). This would need to be addresses before making try to join pin back to blade.

Another way would be to try and find a good replacement aperture blade or make one. Old aperture blades are often thin sheet steel, later ones are often plastic. Pins are often brass or steel.


Bernice

[LabRat]

Figure out what the blades are made of first. If brass, you can clean up under where the pivot pin sits, tin with a tiny amount of solder, and press the pin down with a very hot soldering iron to join them again...

Steve K

[duff photographer]

It only took 6 minutes to get the first entirely unhelpful condescending comment of this thread - thank you internets!

Had to laugh at that - seems the first 2 or 3 hours after posting brings them in for some reason.

Your problem....

Both Bernice and Steve are correct. Any chance you can post an image or two of the 'accident' - not to gloat over of course but to determine the type of repair that'll work.

Duff.

[Randy]

The pins at the end of an aperture blade is often swaged on in much the same way as a rivet. Over decades of being moved, the joint can work loose.

Your description fits my blades. I believe one of the pin holes is torn.

Figure out what the blades are made of first.

My pins are brass but I believe the blades are a plastic - they are very thin and flexible - do not feel like a metal.

Any chance you can post an image or two of the 'accident'...

I'll shoot some very close-ups tomorrow.

Thanks for the input.

[LabRat]

You can tell by taking a pin and scratching somewhere near the pivot where hidden, and examine what color the scratch is... Plastics will feel very slightly warm to the touch, as they reflect your body heat back to you... Metals will draw away your heat and feel cooler...

If steel, a magnet will stick to it...

Steve K

[jim10219]

I’ve used JB Weld to reattach a pin. You have to be careful with it though, so it doesn’t get everywhere. Also, sometimes, especially with a 20 blade aperture, you can remove one entirely and it’ll still work alright. With 20 blades, there will barely be any difference. However, sometimes it can cause the aperture blades to fall out, bunch up, and get damaged. So if you go that route, take it easy and pay close attention to it, and rotate the shutter around to different angles to test it with other directional pulls of gravity. But most of the time it’ll be fine with just one blade removed. Sometimes it’ll even work with two missing blades.

[Jody_S]

It's happened to me often enough that I bought a used watchmaker's staking tool set (example). Of course I haven't had to repair a lens since I bought it, and I haven't bothered to re-open any of the lenses I 'fixed' by removing 1 or 2 damaged aperture blades.

[andrewch59]

I had two pins come loose on my cooke series iia 15 inch, I didnt attempt a fix but sent it straight to sk grimes for repair.
Wasnt hugely expensive albeit the postage.