How to adapt and imperial enlarger thread to a standard metric thread

tonyowen · Sep 26, 2020

I have a 1 1/2" - 24tpi mounting ring for a Wray lens
I have two 39mm [26tpi] standard mounting rings
1 1/2" is 38.1mm
the root diameter of the 39mm rings is 38.02mm
Using masking tape I can get the Wray lens to fit into the standard 39mm ring BUT it tends to come loose. Also I cannot satisfactorily unscrew and re-screw it into the 39mm ring.
Does anyone have any suggestions for long-lasting methods of 'increasing' the 1 1/2" thread so that it can be screwed into and out of the 39mm ring many times.
The reason for asking is that I have a 50mm and 150mm lens that both have 39mm threads, but the mid-sized 108mm [4 1/4"] Wray lens has the 1 1/2" thread.
regards

Tony

choiliefan · Sep 26, 2020

Have you tried teflon plumbers tape yet?
I've had better success with it than paper masking tape.

runswithsizzers · Sep 26, 2020

I don't know if he has something for your specific needs, but a very good source for high quality adapter rings is <Custom Photo Tools> in Portugal. He offers a great variety of adapters, and can do custom work, if necessary.

AgX · Sep 26, 2020

Any fine-mechanical workshop can do that, there is no need for photographic understanding. The issue in this very case though is that there is no space for straight adapting threads, they must be staggered. Though I do not think that the the added extension would matter much here.

mshchem · Sep 26, 2020

Do you have more than 1 lens board?

reddesert · Sep 26, 2020

Don't screw a lens into a ring that has the wrong pitch thread. You will eventually (or quickly) butcher the thread of both the lens and the ring, or worst of all, get it stuck in there, crooked, when the threads gall.

Luis-F-S · Sep 26, 2020

reddesert said:
Don't screw a lens into a ring that has the wrong pitch thread. You will eventually (or quickly) butcher the thread of both the lens and the ring, or worst of all, get it stuck in there, crooked, when the threads gall.

+1! I'd have a retaining ring machined with the right thread!

tonyowen · Sep 27, 2020

mshchem said:
Do you have more than 1 lens board?

Don't understand what you means by lens board in terms of an enlarger.
I have both 39mm and 1 1/2" flanges but I'm trying to avoid the hassle of changing lens flange on the enlarger when I switch from 50mm or 150mm to the Wray lens
regards

R.Gould · Sep 27, 2020

Have a look at SRB, they may be able to help with some sort of adapter to mount the lens, if they do not have a stock item they do make custom adapters, they have done so for me in the past, and as I see you live in the UK, then they would be my first port of call, I know they have helped me out in the past with adapters for some things, and they are not that expensive,
Richard

tonyowen · Sep 27, 2020

reddesert said:
Don't screw a lens into a ring that has the wrong pitch thread. You will eventually (or quickly) butcher the thread of both the lens and the ring, or worst of all, get it stuck in there, crooked, when the threads gall.

I agree in theory, but in practice for this case there is little risk of galling the threads. The threads are 24 and 26 tpi [both Whitworth] and the thread length on both lens and adaptor is short [so the difference between 24 and 26 tpi would hardly be noticeable]. Also the outside diameter of the 1 1/2" thread is the same as, or smaller than the inside diameter of the 39mm mounting ring.

regards
Tony

tonyowen · Sep 27, 2020

R.Gould said:
Have a look at SRB,

Thank you I see they list a 1 1/4" to 39mm enlarger adaptor, so I'll contact them regarding a 1 1/2" to 39mm adaptor
regards
Tony

MattKing · Sep 27, 2020

mshchem said:
Do you have more than 1 lens board?

tonyowen said:
Don't understand what you means by lens board in terms of an enlarger.

If you use something like a Beseler 67, the lenses attach to square boards using retaining rings or flanges, and the boards just snap into the receptacle on the enlarger.
So the best approach with that enlarger is to leave each lens mounted on it's own board.
For Omega D5 or D6, lens plates are used, rather than boards, but it is the same approach.
What enlarger are you using?

tonyowen · Sep 28, 2020

MattKing said:
What enlarger are you using?

an old gnome that does not have what you are describing.
I did not know that some enlargers used lens boards as do 4x5 cameras

regards
Tony

R.Gould · Sep 28, 2020

tonyowen said:
an old gnome that does not have what you are describing.
I did not know that some enlargers used lens boards as do 4x5 cameras

regards
Tony

I have fond memories of gnpme, my first proper enlarger, i was around 15 at the time, but if my memory does not decieve me the lens screw's straight into the body of the enlarger, so no form of lens board,
Richard

How to adapt and imperial enlarger thread to a standard metric thread

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