31.15mm Threads?

[Penumbra]

I'm having trouble finding an answer on this one...

I recently picked up an old triple convertible Wollensak from another member (Thanks, Earl!) and I want to give this thing a decent run-through to see whether I like the results...but the old dual-piston shutter is unreliable at best. So, in an effort to find a working shutter than will fit it, I measured the outside diameter of the threading on the cells: 31.15mm...which corresponds to exactly NOTHING that I can find. When I first saw the lens I thought "Huh, that's close to a Copal 0..." but: no such luck. The pitch on the threads seems to be very close to 0.5mm, but that 31.15mm outside diameter is seemingly singular: I'm looking up pitches in machinists' textbooks and not finding anything with that diameter...so does anyone have any idea on where to go with this?

Secondary option: If a modern shutter isn't available without the several hundred dollars that such an effort will require from SK Grimes - whom also have no experience with this lens, after an inquiry - is there anyone still doing dual-piston shutter repairs?

[Dugan]

I had a lens from a Conley 5x7 that had a faulty Wollensak piston shutter. The lens cells swapped directly into an Alphax shutter (#2?)...also made by Wollensak.

[Penumbra]

The best chart I can find shows the Alphax #2 at a thread diameter of 1-7/32", which is only about .007" different from the 31.15mm that I measured on the Wollensak lens in question...so that may well work. On the same chart, I found that an Ilex #1 is a 1.228" by 40TPI: that's exact insofar as the diameter is concerned, and the threading is only off by a bit (but my estimation with my caliper wasn't that accurate, to be honest). Can the Ilex #1 and the Alphax #2 interchange? For that matter, can the Betax #2 also interchange? If so, that might give me more chances to find a working shutter without dumping a ton of money into it.

[Dugan]

My understanding is that Alphax and Betax interchange, but I have no personal experience to speak from.

[Dan Fromm]

Short answer, Ilex and Wollensak shutters don't interchange.

OP, this site has resources you may not be aware of. One of them is a collection of links to sites on LF gear etc. Go to the Lenses section. There's a sticky "Where to look for information ..." at or near the top. The first post in the discussion has links the collection of links. It includes links to sources for Ilex and Wollensak shutters' dimensions.

[Penumbra]

Short answer, Ilex and Wollensak shutters don't interchange.

I figured they wouldn't; thanks for the confirmation.

OP, this site has resources you may not be aware of. One of them is a collection of links to sites on LF gear etc. Go to the Lenses section. There's a sticky "Where to look for information ..." at or near the top. The first post in the discussion has links the collection of links. It includes links to sources for Ilex and Wollensak shutters' dimensions.

I found the Wollensak shutter page via the Word file, but I think I was going about it the wrong way: I didn't see anything that told me much about the piston shutters, so I started chasing info via the lens threading...but now that I know the Alphax #2 - or the Betax, as best I can tell - will fit, I can start looking for one of those that's in working condition. I'll check the Ilex shutters as well, just to see where they're different.

[Chauncey Walden]

Lock the shutter open and use a Galli shutter. It will be plenty accurate, especially for the converted tests.

[Penumbra]

Lock the shutter open and use a Galli shutter. It will be plenty accurate, especially for the converted tests.

I think you think more highly of my wrist motion than I do!!