I have this manual release cable for a camera. The shutter button unscrews and the manual release screws in the hole.
This particular release has a plunger of 1.5 mm dia which protrudes from a 4mm dia machined tube which holds a return spring. On the end of the tube there's a taper which looks like about 30 degrees (15 deg off the axis) and has a extra fine (this is all japanese mfr metric so maybe they don't call it "extra fine") thread cut into it.
I want to know what it's called and how to figure out how to specify this thread for reproduction.
Carefully take a micrometer and determine the OD of the tops of the thread. This will be just tiny bit smaller than the usual metric size (perhaps
2mm).
Then in a number of mm of length, who many threads can you count? You should express this as mm per thread (I believe). There may also be a thread pitch gage, that will do a much better job of determining this thread.
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for "thread pitch gage" select the link for "Metric Screw Pitch and Bolt Gauge" "Metric Screw Pitch and Bolt Gauge Measure the outside diameter of threads from 2.3 mm to 24 mm with this sturdy steel gauge. It includes a removable screw pitch gauge for measuring metric thread pitches from 0.35 mm to 3 mm. Overall size is 9 1/2" Wd. x 4
1/32" Ht. 8567A11 Each $9.44"
Nice tool and reasonably priced. But this screw's thread OD varies along the length of the aforementioned taper. think of it as a spiral wrapped on a cone.
This is a similar thread then to a tapered pipe thread. But these are not common in the metric world. Gaging methods should be similar, but are not trivial. Some good information could be gained from an optical profilometer. Do you have access to one?
This is more of an oddball situation than I thought. It appears that not all camera releases are created (threaded) equally, but this taper thread seems to be one taper and pitch only.
Where have you seen a pipe with a 30 degree taper?
"It" = "taper" "which looks like... and has..."
If what I just read is correct, the root dia of a pipe thread is constant but the pitch varies slightly along it's length so that at a certain point it jams. And then I've read the different info.
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The engineering reason for a taper screw is also given in the above link.
as well as the blasted std. which costs $22
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or $16 euros for DIN 19004
The guys in that discussion measured their release cables and one was 3.4 mm major dia. .5mm pitch and 30 degree taper as I guessed.
Except the last post where the guy converted from inches to mm and differed. He came up with 3.2mm. He also gave a different definition of pipe thread.
Unless they were measuring root dia or pitch dia., there's some different designs which may use the same thread. I *did* come up with .5mm pitch - 7 threads over 3.5mm thread length.
My releases ( I have 2) both start with a 4mm major dia. and I have no way of measuring the other dias. I'll try a machinist to get better measurements. Unless a machinist blew $22 on the spec for this oddball thread, he won't have it and I may as well draw the thing.
I could just call it M(2.3-4.0)-0.5 or M(2.3-4.0)P0.5 and indicate a 30 degree taper, no?
Note my question about an optical profilometer. You clamp your "screw" in this device, and an enlarged shadow outline is cast on a screen. You can analyze the pitch, angle, angle of thread, and OD easily this way.
Found the following info on Google Groups, I don't know if it'll help you. The standard being referred to is FED-STD H28/18, "SCREW-THREAD STANDARDS FOR FEDERAL SERVICES, SECTION 18 PHOTOGRAPHIC EQUIPMENT THREADS"
Lance
*****
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to Federal Standard for "Photographic Threads" Section 18.
50 tpi
28 degrees over all, in one place, 14 degrees 20' (x2) thread is 60 degrees included entrance size is (the hole) 0.146 plus/minus 0.004" thread height on an angle 0.0128" depth of hole (female) 0.105"
Might help for future ref and the GPO might be cheaper than ISO, JIS, and friends. It's most likely what's used in photo reconnaisance equip.
I have to assume from the link to that discussion and where it lead that these Copal shutter releases all use one of several threads, the taper thread being one. They're Japanese and metric.
that's .787 mm pitch. Copal lists a .5mm and .7mm pitch standard metric thread, but the tapered one measured in the discussion was .5mm
Ugly federal crap. They should have used the JIS std. Then we could use their equipment after we shoot them down. Of course these days, were more likely to shoot down equip of Russian or French manufacture.
oops. i hit the divide key. try it with 25.4. you'll get .787 roughly. error, error. The diff is .008 mm (using 25.4) which is within the tolerance of the fed spec of 4 mil. I guess that federal spec isn't too far off. 28 deg vs 30 deg would work for the socket if not the male connector.
Too bad that NG thread is from 2000 and the guy never did answer where he got the spec., GPO, website, wherever.
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