Rescuing a Dallmeyer 3B

[Steven Tribe]

Unlike a recently mentioned 3A - the problem here is not cells stuck in the barrel - but rather no barrel at all!
Obviously a previous owner had problems with the iris (this the front turning soft adjustment version with the flange thread right at the back) and put the cells away for safe keeping. His destiny was such that never got round to fixing it and the loose cells were passed on together with the studio camera they had been used on (my theory, anyway).
Thanks to help here, I confirmed that it was indeed a 3B and Alex was able to give me the exact barrel length and position of the Waterhouse slot.
The preliminaries will be spread over a few quick postings as illustration, I think, is worth more than words!
I don't have a lathe set up for cutting threads so I have a system using soft solder on a slightly oversize brass tube and the existing cell threads to "cut" a thread. This system has worked very well. However I don't know about how well these threads will stand up to time. At present they are absolutely solid - but I don't know how moveable the threads will be when the "threaded" solder has time to age and develop an oxide skin.
The first group show the cells and they basic structure. The second shows "scribing" the 14.4cm on the brass barrel stock and the last the use of a hacksaw.



All the original photos were lost in LFPF crash long ago.
I found a few photos which illustrate the result!

[Jim Fitzgerald]

Steven, this is great. How did you find the right diameter brass barrel? I have a 14" commercial Ektar in a Walnut barrel that is cut for waterhouse stops. I like yours better!

[Steven Tribe]

I have had the section of brass tubing around for over a year - I thought it might come in useful! It has an internal dimension which is exactly 1.5mm more than the Dallmeyer threads. Pure chance!
The photos show the finishing of the hacksawn edge. Two grades of paper placed on an absolutely plane slate block (available in the kitchen!) good pressure and a check with a micrometer. This is followed by rough cleaning of the inside half inch at both ends. Then soldering of about five "patches" inside both edges. Heating from outside and underneath the barrel. Allowed the solder to flow out quite a bit and form a flat area. This can be done continually around the barrel without melting the finished "patches".
When cooled, I used a fairly rough curved file to even out the 5 sections and make a slightly wider diameter to start the thread.
Then it is just a question of using the existing male thread on the lens cells to "cut" a thread.
Brass is way stronger and harder than soft solder so there is no chance of damage to the original thread. There may be some slight wear but much less than in difficult brass to brass or aluminium to brass threads.
Getting the thread to start may require extra filing and a sudden stop should be investigated. It is fairly easy to spot the source of difficulty. The cut solder doesn't collect in a sensible place as with traditional thread cutters so frequent unscrewing and removal of loose metal is necessary. It is easy to cross thread so you have to be careful. A single cross threading didn't make scrap out of the whole project!

[goamules]

Excellent project!

[Steven Tribe]

Daylight has gone here - so completion of the Waterhouse stop supports within the barrel will have to be tomorrow. I will keep these as narrow as possible not to reduce the speed. The "rescue" is beginning to look like something that may well work.
I will have more left of the barrel than I have actually used so will post details of internal diameter if someone else has a similar need.

[Stephane]

What are you going to engrave on it, if you ever thought about it?
By the way, I am fixing the negative that saw light (and some curves ) through your big Plasticca!

[Steven Tribe]

I assume you have a 3B or similar, Stephane?
I have thought about a label rather than engraving.
Dymo to start with.
Something like-

Dallmeyer 3B
Serial number between XX,XXX and YY,YYY

Which will correspond to the period when this brass front adjust version was made.
Or perhaps Seán has some unused numbers in his Dallmeyer ledger!?

[jb7]

Wonderful luck with the internal dimension of that barrel-
I don't reckon the size of the frame for the stops is going to influence the speed of the lens very much-

Good luck with this-

Serial number? STD3B? Maybe not...

[Steven Tribe]

I had measured the inside diameter of the brass tube several times before. I needed a short piece for a lens hood! It was always a big too large. I realise that finding a 3B that was exactly the right size was more than unusually lucky. It is not as though I had dozens of these brass tubes in my material boxes!
The remaining piece is 27cm long, internal diameter 9.67cm, wall thickness 1.66mm.

[Jim Fitzgerald]

Steven it looks like this was meant to be! Have fun with it and be sure to update us with some images when you can.