A thread, thread?

Charles Webb · Mar 14, 2005

I am sure that others besides myself have had such a problem, but this is the first time for me. I have several old shutters that the internal threads of
of the cable release socket are damaged or stripped. The shutter I have in my hand is Betax and the attachment point for the cable release is a square
shank with external threads, the regular tapered thread is in the end of this
shank. The tapered threads are damaged and will not allow the release to attach. The external threads on the shank are pristine and seem to be begging "use me" "use me", however I can't figure out what size the thread is
to make an adapter.

I would bet a cherry popsicle that I am not the only one who ever had this problem. I like my Wollensak and Turner Reich lenses and normally use the old Degroff air releases on all of my lenses. I am afraid I will ruin the brass tipped fitting on the Degroff air pistons by attempting using them in the damaged threads. Degroff hasn't made these little guys for quite awhile so
I want to protect what I have. I actually would like to come up with a cable release that utilizes both the internal and external threads.

Any suggestions ? Any one know what that external thread size is?

Many thanks in advance!!!!

Ole · Mar 14, 2005

That's why I own a caliper and a thread gauge!

Now, anyone know what to do about a shutter with shredded mounting treads?

Charles Webb · Mar 14, 2005

Ole,
I have a few toys too, dial indicaters, micrometers, a milling machine, drill press and 4 lathes. Taps and dies of most sizes, but these threads just don't wanna play fair, nothing matches up to anything I have to measure with!
Metric, Whitworth, and ASA nothing matches.

For a shutter with shreaded threads, I would first determine what the original thread was, chuck it up and hand feed it in the lathe. Problem arises because most lathes do not cut the needed threads used on camera equipment. Most are set up to a standard that does not include any thing I want to do!

MurrayMinchin · Mar 14, 2005

Hi Charles,

That happened to me as well. I rocketed back into town and found a solution that I figured would be good enough for the day. Small 1/2" diameter glue on velcro patches. One went on the lensboard above the shutter release, the other went on the cable release. I just slip the "plunger" end of the cable release into the stipped shutter threads, then push the velcro bits together.

It aint pretty, but trees could care less...that was a couple years ago.

Murray

claytume · Mar 14, 2005

Charles Webb said:
The external threads on the shank are pristine and seem to be begging "use me" "use me", however I can't figure out what size the thread is
to make an adapter.

Charles

you're later reply suggests you have the equipment to measure the thread.

What is the diameter and pitch?

I'll have a look through some of my reference books to see what I can come up with.

Clayton

wfwhitaker · Mar 14, 2005

Charles Webb said:
... The tapered threads are damaged and will not allow the release to attach. The external threads on the shank are pristine and seem to be begging "use me" "use me", however I can't figure out what size the thread is to make an adapter....

Any suggestions ? Any one know what that external thread size is?

The stock answer is to send it to SK Grimes.

Charles Webb · Mar 14, 2005

You are correct in your statement that I seem to have all the equipment necessary to measure the pitch of the threads. But alas the measurements
do not correspond to or match up to a thread checker or any tap or die available in American Standard NF, NC, NS. It does't match up with Metric or Whitworth thread checkers. I have made many such adapters and modifications on many cameras, but this thread pitch on the Betax has me stumped. Thus I asked for help.

I have asked the same question of SK Grimes, but have had no response at this point.

Before I asked the question I researched every source I could find for an answer, but came up empty.

Dave Parker · Mar 15, 2005

We went through a discussion of this nature about a year ago over on the graflex.org website, it seems to me, we could not find the answer after over two months of discussing it, I know many of us, took to looking at several of the watch makers shops and still could not come up with the solution.

after a while the thread died, but you might pop over and ask RichS, if he ever found the solution to this problem.

Here is the thread we were discussing this very thing in.

http://www.graflex.org/helpboard/viewtopic.php?topic=2596&forum=10

Maybe something there to help

Dave

Charles Webb · Mar 15, 2005

Thanks to all who have tried to help with my question. Dave I will try your suggestion and if I come up with anything I'll post it for all!
C Webb

claytume · Mar 15, 2005

Charles Webb said:
You are correct in your statement that I seem to have all the equipment necessary to measure the pitch of the threads. But alas the measurements
do not correspond to or match up to a thread checker or any tap or die available in American Standard NF, NC, NS. It does't match up with Metric or Whitworth thread checkers. I have made many such adapters and modifications on many cameras, but this thread pitch on the Betax has me stumped. Thus I asked for help.

Charles

this is an interesting subject for me, prior to changing careers I had over 20 years experience as a machinist. I've seen these odd balls before and there's always an answer.

Can you measure the thread diameter and also give me an approximate thread pitch, metric or imperial. I'd like to research it further.

Clayton

Donald Qualls · Mar 15, 2005

Ole said:
Now, anyone know what to do about a shutter with shredded mounting treads?

Simple method: Send it to S.K. Grimes, wait a bit, write a check (or send your credit card information).

Cheap way: if you don't mind boring your lens board oversize or using one with a larger hole, you can probably find a piece of PVC pipe with threads on that fits over the existing threads. Cut a section of just the threads, and glue it onto the shutter threads with epoxy (be *very* careful not to epoxy anything that shouldn't be, like the glass or the aperture leaves or operating lever). Cut a similar portion of a threaded union that fits the pipe piece to make a new retaining ring.

Less cheap, better way: if you have access to a lathe, you can turn an externally threaded brass or aluminum sleeve that fits snugly over the damaged threads and attach it as above, using a matching internally threaded tube as the retaining ring. This is better because pipe threads are tapered, and might require some fitting to get them to be tight enough on both the lens board and the threads, because the metal threads are stronger and less prone to damage if you have to remove and replace the lens on the board, and because the job will look a lot more professional (which affects resale value) if done with metal.

Charles Webb · Mar 16, 2005

Clayton,
Sorry for not getting back to you earlier.

The outside diameter is 0.215 and the closest TPI is close but not an exact fit
to a 36 thread guage. I measured several shutters and all seem to be close to these numbers. At present I am checking 12-36, but have neither a tap or die in this size.

Thanks!

Charles Webb · Mar 16, 2005

Dave,
I read the comments posted on the link you provided, whew, they pretty
well wrung the topic out, but like myself, did not find a simple solution.

Thanks for your interest!

Charles Webb · Mar 16, 2005

Donald,
Good information, I have done the sleeve thing with brass, and it worked well, have not tried PVC but believe it would work. My actual problem/question was a repair for my Betax type of shutters with buggered
internal cable release threads. There is a square shank that the internal threads are cut into. They also have an external thread that I would like to utilize but so far have not been able to tell exactly what the the thread is.

Thanks a bunch for your input.

claytume · Mar 18, 2005

Charles Webb said:
Clayton,
Sorry for not getting back to you earlier.

The outside diameter is 0.215 and the closest TPI is close but not an exact fit
to a 36 thread guage. I measured several shutters and all seem to be close to these numbers. At present I am checking 12-36, but have neither a tap or die in this size.

Thanks!

Charles

you do indeed have an oddball there, 12-36 isn't listed on standard charts but does appear on full spec charts which list UNS series which are basically combinations used if the standard series don't meet a manufacturers requirements.

These are the 12's listed

12-24 UNC

12-28 UNF

12-32 UNEF (extra fine)

12-36 UNS (special)

12-40 UNS

12-48 UNS

12-56 UNS

I've struck UNS before on some common things, can't remember what? but it seemed to me they were used (in this instance) to stop people substituting standard parts.

Generally the answer is to hand manufacture the parts which means either making a tap for the internal mating thread or screw cutting it. Yes not an easy job on such a small component.

The other thing too, I'd be worried about getting a true reading on the thread pitch, it's doubtful it's a 35 or 37 and it doesn't appear to be close to anything metric.

hope this helps!

Clayton

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