[cheaper] Custom flanges?

[Jim Graves]

I have used what I call external 'snap' rings - retainers.
They come in very many sizes with close increments.
Here is my better reference. http://smretainingrings.com/XB%20RING%20SPECS.pdf

You want to look at the column marked "FD" - Free Diameter (internal diameter).

Also Google for "constant section ring" and "spirolox" for other approaches.

Use two - one on each side of the lens board.

Jac ... trying to visualize how you use these ... do they fit into the valley of the threads on the base of the lens which would normally screw into the flange? If so, how do you secure the fasteners to the board? And, what thickness do you use?

Jim in Sacramento

[Jim C.]

What a brilliant idea!

(I wonder if a certain French cheese manufacturer has seen their "logo"...)

RR

I'm sure they did, but I think it would be easy to differentiate foil wrapped wedges of spreadable cheese
from metal snap rings.

[Jac@stafford.net]

Jac ... trying to visualize how you use these ... do they fit into the valley of the threads on the base of the lens which would normally screw into the flange? If so, how do you secure the fasteners to the board? And, what thickness do you use?

Jim in Sacramento

They are too thick to fit in the valley of the thread. Instead, the proper size will grip tightly. Using one on each side right up against the board will keep the lens in place. These fit using a special kind of pliers. You need a large one for the large rings. Google Image "Large Retaining Ring Pliers". Be sure you look for external ring pliers, or dual-purpose (external and internal). (I never found a way to improvise the tool.)

[civich]

Jac,
This is very interesting. Do the retainer clips damage the (usually brass) threads in any way that would prevent the shutter/lens from screwing into a normal flange later? Is the connection tight or just adequately tight? This may be an inexpensive solution to my Betax 3 shutter flange need while I wait for one to pop up here or on ebay. -Chris

They are too thick to fit in the valley of the thread. Instead, the proper size will grip tightly. Using one on each side right up against the board will keep the lens in place. These fit using a special kind of pliers. You need a large one for the large rings. Google Image "Large Retaining Ring Pliers". Be sure you look for external ring pliers, or dual-purpose (external and internal). (I never found a way to improvise the tool.)

[Jac@stafford.net]

There is always a risk of munging up brass threads, and I did not consider the shutter issue. The retainer is rather a last-resort for me. You have to measure the existing thread area and choose the retainer carefully so that it just fits.

[gevalia]

I bought a Heliar a few years back from Jim Galli. I asked him for a flange to go with it and I remember him saying he had a drawer full. You may want to ping him. Or how about Eddie Gunks.

[civich]

Hmm. Still, an interesting, creative & inexpensive alternative or stop-gap until the correct flange shows up. Thanks for the info. -Chris

There is always a risk of munging up brass threads, and I did not consider the shutter issue. The retainer is rather a last-resort for me. You have to measure the existing thread area and choose the retainer carefully so that it just fits.

[goamules]

Personally, if I don't have a flange, my main goal with mounting is to keep the threads in good shape in case I ever find a flange. The best way to do this is not to use metal on metal, and not to use glue.

I've been doing what Mark Sawyer taught me - use a soft rubber hose clamp, from Home Depot. These have a ring of rubber, which you can split to fit precisely on the threads. Over the outside of the rubber, in a nice groove, is the hose clamp. They hold the lens by the barrel tube at the rear, very firmly keeping the front fillet against the wooden lens board. I think he posted a picture here somewhere.

[Leigh]

Regarding the cost of manufacturing a one-off flange for an odd lens...

This has to be done by a machinist on a manual machine.
Computer-driven machines are not financially viable for one-offs.

Add to this the fact that vintage lenses probably use 55° Whitworth threads, rather than
the modern 60° threadform. This has to do with the shape of the thread cross-section.

You cannot cut 55° Whitworth threads with modern thread-cutting tools. You must make
new tooling specifically to cut those threads, and it's not usable for modern threads.

Everything in this world costs money.

- Leigh

[wombat2go]

Good Morning Leigh,
I purchased from a UK supplier, a set of threading tools which are 55 degree Whitworth on one end and 60 degree for iso metric / USA threads on the other.

My hobby lathe here in USA is geared for inch threads and the gear set for conversion to metric threading is too costly for me.
After a lot of search assisted by a specialist in Australia I have just purchased a compound gear which will fit on the quadrant and allow the lathe to do metric threads for camera lenses.

The history was as I read, in 1800's British lathes were the best, so the camera makers in Germany and France used them to make "Metric Whitworth" threads of which the Leica M39 26 TPI 55 degree Whitworth lens mount is an enduring example .

I can make that thread here and with the new gear, I should be able to make the iso metric thread too.

So I am working on a project to adapt a 1957 Prontor ( 60 degree, metric) to the M39 ( inch, 55 degree Whitworth) on a Graflex lens board.
Dan Fromm has advised me of the cons of putting lens inside the lens board but i will do it anyway to get some experience.

Cutting internal camera threads on the old lathe is a bit of challenge; the lead screw has to be engaged for the whole session, light cuts, one mistake and it is in the scrap bin !