Mounting Synchro-Compur Shutter

mossbloom · Mar 30, 2014

I just bought a wonderful old Rectagon 3-inch lens (75mm) mounted on/in a Synchro-Compur shutter, but there's no mounting nut for the shutter so I can't mount it on the lensboard. I measure the threads as about-39mm, but a lens nut in that size from Adorama doesn't screw on. It gets started, meaning it's close, but it jams, which means no cigar. My thinking is that the pitch of Adorama's nut is too coarse: the shutter's threads are pretty fine. Does anyone have any ideas as to either thee thread size or where I might find a nut?

Thanks Al

Dan Fromm · Mar 30, 2014

http://www.skgrimes.com/products/mounting-flanges/metric-stock-flanges

mossbloom · Mar 30, 2014

Aha! Thanks very much! So it IS a thread pitch issue. Now all I have to do is find the nut.

Al

shutterfinger · Mar 30, 2014

39x.75 mm

fotch · Mar 30, 2014

Maybe ship them lens paying cost round trip? Or perhaps a local machinist can meausre?

John Koehrer · Mar 30, 2014

Or cut the mounting hole in the board, wrap it in gaffers tape & screw(!) the lens into the board.

Don't laugh, it's been done a lot more than you would expect.

BrianShaw · Mar 30, 2014

... or if it is a wood lens board, cut the holes so they "self-thread" when the shutter is screwed in. Don't laugh, it really works.

Tom1956 · Mar 30, 2014

BrianShaw said:
... or if it is a wood lens board, cut the holes so they "self-thread" when the shutter is screwed in. Don't laugh, it really works.

I make all my own lensboards out of hobby plywood from the model airplane store. And whether I have a retaining ring or not, I always sand out the hole size so the shutter self-threads into the wood. And if you don't have a retaining ring, a bead of hot glue from the hot glue gun finishes up everything nicely. And if you want the shutter back out someday when you do find a ring, the hot glue cleans off fairly easy. Not having the ring never really bothers me. It's always nice, but not essential.

fretlessdavis · Mar 30, 2014

Tom1956 said:
I make all my own lensboards out of hobby plywood from the model airplane store. And whether I have a retaining ring or not, I always sand out the hole size so the shutter self-threads into the wood. And if you don't have a retaining ring, a bead of hot glue from the hot glue gun finishes up everything nicely. And if you want the shutter back out someday when you do find a ring, the hot glue cleans off fairly easy. Not having the ring never really bothers me. It's always nice, but not essential.

You could probably do the same with a Polymer clay. It may cure into something that vaguely resembles a nut and may even be able to be reused.

BrianShaw · Mar 30, 2014

Doesn't polymer clay need to be baked to harden? I've never baked a shutter before and don't know if that would be a good thing... but suspect that it might not.

fretlessdavis · Mar 30, 2014

BrianShaw said:
Doesn't polymer clay need to be baked to harden? I've never baked a shutter before and don't know if that would be a good thing... but suspect that it might not.

You could get it to a fairly firm consistency, thread the shutter in and out until it's smooth, then finish curing it.

I think there are also a few polymer clay or similar materials that cure at room temp for extended periods of time.

EDIT: Looks like dimensional stability of the room temp/air drying stuff isn't very good, actually...

Tom1956 · Mar 30, 2014

Why make it harder than it is? Brian Shaw's idea works perfectly. A little hot glue finishes the job. It's just too easy. This baking business is begging for trouble in the temper of the internal springs.

fretlessdavis · Mar 30, 2014

Tom1956 said:
Why make it harder than it is? Brian Shaw's idea works perfectly. A little hot glue finishes the job. It's just too easy. This baking business is begging for trouble in the temper of the internal springs.

I never advocated for baking the thing... get it nice and firm, thread in and out to make sure it's smooth, then pull it OFF and cure it.

Tom1956 · Mar 30, 2014

Won't it shrink? But it's your idea, so give it a try. All we've done is put one out there that works. But I've only been in photography 45 years, so it's not impossible I could still learn something. GL.

fretlessdavis · Mar 30, 2014

Polymer clay has pretty good dimensional stability. I haven't done it specifically with a shutter, but I have done it with other threaded pieces. I also tried something similar to your way, and it didn't hold up on one of my bigger lenses. After getting vibrations for a while in a pannier on my bike, it started to fall out. Good thing I noticed, otherwise it would've fallen onto a bunch of rocks.

Jon Shiu · Mar 30, 2014

just look on ebay for a Copal 1 ring.

Jon

mossbloom · Mar 31, 2014

Thanks!

oldlincoln · Apr 3, 2014

I have bought a couple in 0 and 1 from a seller called "heavystar". Very nice rings, they look just like the ones Schneider sells for $30 for around $10 shipped.

Tom1956 · Apr 3, 2014

Good. Always best to do it right.

Mounting Synchro-Compur Shutter

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