Steven Tribe
15-Dec-2013, 07:22
This is a system that I have described before for making a brass flange for Dallmeyer 3B. It is far better permanent system for mounting a brass lens hood than a flange to a brass sleeve.
Only a few of the heavy (over 2 kilos) portrait petzvals are less than 100 years and during this time they often lost parts. Flanges are a common loss, but the big brass lens hoods have often been removed too.This is not such a problem as the flange but still represents a real loss.
I have an, otherwise complete and unmodified, Petzval made by Waibl in 185?. Without the lens hood.
After 24 hours, I got tired of the lacking hood, so I made one yesterday.
From the few photos of complete Waibl available, I found it was basically the same as the other Viennese makers, like Voigtlander and Dietzler. A triangular profile brass ring (like the extra brass ring on the sleeve accepting the flange) with the hood tube attached (solder?).
This construction is beyond my metal skill/tools, so I decided to make a brass hood of the same diameter as the current sleeve - with a thread on the inner surface of the hood matching the original thread on the barrel end.
I used the same brass tube I had used for the 3B (co-incidence) with a shorter cut section of the same source brass tube. This was cut through and the effective diameter reduced to fit inside the hood proper. The reduced internal diameter had now under 1 mm clearance over the mounting thread on the barrel. The two hood parts were then soldered together (using soft electronic solder which is easy to remove from brass surfaces). Finally, I soldered 4 1 cm blobs of solder internally at the the edge and filed these down until the hood could be screwed in, cutting a basic part thread in the solder at the same time.
The photos below are, I hope, self explanatory.
The brass will have to age a little before I can do a matching lacquering.
Only a few of the heavy (over 2 kilos) portrait petzvals are less than 100 years and during this time they often lost parts. Flanges are a common loss, but the big brass lens hoods have often been removed too.This is not such a problem as the flange but still represents a real loss.
I have an, otherwise complete and unmodified, Petzval made by Waibl in 185?. Without the lens hood.
After 24 hours, I got tired of the lacking hood, so I made one yesterday.
From the few photos of complete Waibl available, I found it was basically the same as the other Viennese makers, like Voigtlander and Dietzler. A triangular profile brass ring (like the extra brass ring on the sleeve accepting the flange) with the hood tube attached (solder?).
This construction is beyond my metal skill/tools, so I decided to make a brass hood of the same diameter as the current sleeve - with a thread on the inner surface of the hood matching the original thread on the barrel end.
I used the same brass tube I had used for the 3B (co-incidence) with a shorter cut section of the same source brass tube. This was cut through and the effective diameter reduced to fit inside the hood proper. The reduced internal diameter had now under 1 mm clearance over the mounting thread on the barrel. The two hood parts were then soldered together (using soft electronic solder which is easy to remove from brass surfaces). Finally, I soldered 4 1 cm blobs of solder internally at the the edge and filed these down until the hood could be screwed in, cutting a basic part thread in the solder at the same time.
The photos below are, I hope, self explanatory.
The brass will have to age a little before I can do a matching lacquering.