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-   -   Imperial to metric enlarger lens adaptor (http://www.film-and-darkroom-user.org.uk/forum/showthread.php?t=13441)

tonyowen 2nd October 2020 02:39 PM

Imperial to metric enlarger lens adaptor
 
I have a 1 1/2" - 24tpi mounting ring for a Wray lens
I have 39mm [26tpi] standard mounting rings
[1 1/2" is 38.1mm, the root diameter of the 39mm rings is 38.02mm]

However, the outside diameter of the Wray lens' 1 1/2" thread is the same as or slightly smaller than the threaded bore of the 39mm ring.
In addition the lenght of the male and female threads is very short so the difference betwene 26 and 24tpi is of little effect.

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.

It has been suggested that SRB could make an adaptor - that do 1 1/4" to 39mm - I have yet to contact them.

regards

Nat Polton 3rd October 2020 06:15 PM

I wonder if PTFE tape as used by plumbers on threaded fittings would be OK.
It will not last forever if being screwed and unscrewed umpteen times, but it may last longer than masking tape.
It is cheap and easy to get in d.i.y. shops. Or cadge some off a friend to see if it works before buying a roll.
Cheers.

Mike O'Pray 3rd October 2020 07:09 PM

Good thought Nat Certainly on metal pipes I found that PTFE tape would allow me at least a couple of screwing and unscrewing and after this number I tended to replace because its purpose was to prevent water leaks. It is much thinner and more flexible stuff than masking tape and quite cheap

Tony, in your case where water leaks aren't a consideration you might well find it works OK for several more screws and unscrews

I suppose key to this is how frequently this needs to be done

Mike

Martin Aislabie 4th October 2020 12:39 PM

Hi Tony

Only a suggestion - but do you have a local machine shop that could make you an adapter ring/tube ?

Have one end machined for the Wray and the other for the 39mm thread.

Another solution is to have a locking flange machined - push the lens through the 39mm plate and then screw on the locking wring for the Wray.

Some large enlarger lenses (LF/ULF) have used locking flanges as their mounting method.

Best of luck

Martin

tonyowen 4th October 2020 01:30 PM

Quote:

Originally Posted by Martin Aislabie (Post 135940)
Another solution is to have a locking flange machined - push the lens through the 39mm plate and then screw on the locking wring for the Wray.

unfortunately the short thread lenght will not allow this

regards

Nat Polton 4th October 2020 07:57 PM

3 Attachment(s)
Whilst the following idea is very much Heath Robinson it may get you out a spot until you can get a decent lens panel or adaptor made.

My idea is to use the enlarger red filter holder beneath the lens as a support to stop your lens from wobbling.
When I tried it on my lens it still allowed the aperture adjusting ring to turn on the lens.

I do not use the red filter, but used to use the holder for a diffuser on a colour analyser. Hence the frosted plastic instead of red filter.

The brownish filter is meant to represent a hole cut into a plywood or plastic disc. The hole then allows the image to pass through and the plywood disc supports the lens.

Very crude I know, but it should work until you get sorted with something purpose made.

Have a look at the pictures.

The frosted disc represents a plastic or ply or metal disc with a hole cut in it big enough to support the lens.
The brownish filter represents the hole to let the light through.
The final image is the support in situ.

Good Luck and Cheers.

http://www.film-and-darkroom-user.or...1&d=1601841337

http://www.film-and-darkroom-user.or...1&d=1601841337


http://www.film-and-darkroom-user.or...1&d=1601841337

tonyowen 5th October 2020 07:42 AM

Quote:

Originally Posted by Nat Polton (Post 135963)
My idea is to use the enlarger red filter holder beneath the lens as a support to stop your lens from wobbling.
When I tried it on my lens it still allowed the aperture adjusting ring to turn on the lens.

Good thinking - it might well work

regards

Tony

Flack 25th March 2021 08:12 PM

I have just made a lens mount and 3d printed it for my Opemus 6 ..

Flack :)

Terry S 26th March 2021 12:53 PM

Quote:

Originally Posted by tonyowen (Post 135882)
It has been suggested that SRB could make an adaptor - that do 1 1/4" to 39mm - I have yet to contact them.

regards

That would be my first choice. If they don't have one made already as part of their vast selection, I'd still approach them as they are known for making bespoke items.

Terry S

billcowan 26th March 2021 01:21 PM

I had a very good adaptor made at a very reasonable price from
https://customphototools.com/contact/
Very good work.


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