Unscrewing Voigtländer Euryscop IV #5 glass fitting

[matvogel]

Hello,

Does anybody know how to open the glass fitting of the two optical elements from a Voigtländer Euryscop IV #5 ? I can easily unscrew the front and rear element from the barrel but need to take out the glass element as well. I want to send the pure brass part to a mechanical craftsman who will make me a flange.

Is there a way to further unscrew the brass parts or is the glass element mounted in a different way?

Thanks!
Matthias

84940

[Steven Tribe]

I have checked the x section in catalogues and your image and it looks distinctly like a thin brass edge that has been turned over in a lathe. This is a system that became the rule rather than the exception late in the 19th century.
The ragged edge next to the glass face that I think I can see, suggests that the brass has been opened again.I don't remember the technical lathe term for this operation. Someone who can make a flange on a lathe should be able to lift the edge, I think.
Strangely, my own series IV (no. 2) serial number 37343, has another method - pressure edge rings. There must have been a change sometime. Suter used this loose (not so loose!) edge rings.

[matvogel]

I have checked the x section in catalogues and your image and it looks distinctly like a thin brass edge that has been turned over in a lathe. This is a system that became the rule rather than the exception late in the 19th century.
The ragged edge next to the glass face that I think I can see, suggests that the brass has been opened again.I don't remember the technical lathe term for this operation. Someone who can make a flange on a lathe should be able to lift the edge, I think.
Strangely, my own series IV (no. 2) serial number 37343, has another method - pressure edge rings. There must have been a change sometime. Suter used this loose (not so loose!) edge rings.

Thanks Steven,
now I understand why I cannot unscrew it further. So I have to send the craftsman the entire lens in order to build the flange.

[Steven Tribe]

There so little edge in the photo, that I fear that 99% of the edge has been machined away. The lens is staying in position by habit, a few mms of brass edge or remnants of lens edge balsam. It is worth a closer check, I think, before you use USPS.

[E. von Hoegh]

I can't be sure without an edge-on view of the cell, but there may be an "L" section ring screwed on to the cell which retains the glass.

[Steven Tribe]

I have been too focussed on the bare brass rough edge! The pressure edge ring (or L formed ring) is there and it is the dark ring between the barrel proper (which ends where the rough brass edge ends)and the glass. My experience with other of this type is that it is not a screw - but a pressure - fit.

[E. von Hoegh]

A good way to loosen that is to place a sheet of neoprene or rubber, such as a jar lid gripper, on the table top and press the ring down on it while turning the outer edge of the cell. The ring is so thin that gripping it with the fingers can make it very hard to turn.

[Steven Tribe]

I have just been looking at an Suter F5 aplanat, which has the same cell system as the Voigtländer glass mounting.
This was very easy to get apart (it was already loose!) so I thought I might show what it looks like - instead of long descriptions!
Just a pressure mount, with a little burnishing - no threads.