If it's an imperial lathe.
Screwcutting lathes are either imperial or metric, and most by now will be metric (made or converted). Cutting the "wrong sort" of thread requires a 127 tooth changewheel. Small lathes don't have the banjo space for such a big wheel and even on large lathes they're quite a rare accessory (and keenly fought over when they show up).
Yes you can get 1/4 BSW stuff in the UK. I walked into my local engineers merchant (Hughes and Holmes for those that know where) and bought a 1 3/8 BSW cap head screw to fit my webcam to a piece of trunking two weeks ago. No trouble at all even if they did charge me 20p.
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The standard tripod screw size is "quarter-inch Standard Whitworth" (a British standard, originally), as others have mentioned. A larger 3/8" size is less common, and there are adaptors between the two sizes - the neatest being a short slender tube with a 1/4" thread on the inside and
3/8" on the outside.Small hardware shops will probably have Standard Whitworth nuts and bolts in stock, or be able to make them in the back room if they're really old-fashioned and helpful.
Camera shops often have all sorts of gadgets made to be attached using this size of nut and bolt - possibly including old or not-so-old 'ever-ready cases' and things for holding lamps or reflectors. Telescopes and binoculars often have standard tripod-screw fittings too.
On Fri, 28 Apr 2006 21:06:49 +0100, Andy Dingley had this to say:
My Myford Speed 10 is still Imperial :-)
The message from "Pat" contains these words:
If it's going to be so difficult to find a nut that will fit (i.e. getting someone to make it for you, having to raid a museum etc.), how about changing the bolt in the tripod to one with a more modern thread?
Mainly based on American Fine and American Coarse with some subtle differences. Came about just after WW2 when the UK was exporting many cars to the US - long before James Bond. ;-) In use up until the mid '70s when metrification came about. Which is why few garages would have BSW nuts and bolts since they haven't been in common use on cars for about 50 years. ;-)
We have lots of Whitworth bolts and nuts, from 1/8" to 9/8" Here's a picture of them:
And that will screw into the camera body?
There's no problems getting the correct thing - just don't expect a shed or hardware shop to stock a near obsolete thread.
Plenty of people have pointed out that the best answer is a 1/4"-20 nut. If you really can't find this size nut, you might be able to make a fastener. How heavy is the attachment, and how secure does it have to be? If it's not too heavy, you might be able to make your own fastener by doing this:
-Get a small piece of fairly strong plastic (unfilled nylon, PET, PBT...not an acrylic or epoxy)...maybe one of those little protectors that goes on an exposed screw thread on a bicycle so you don't cut yourself or snag your clothes. Perhaps you could use a plastic spacer or standoff;
-Drill a hole in the plastic. The hole size should be just at or slightly larger than the "minor diameter" of the screw (i.e., the diameter at the bottom of the threads). You can "eyeball" that by holding the drill bit behind the screw;
-Using a pliers or Vice-Grips, hold the plastic, and screw it onto the tripod screw. The metal screw will cut and form the threads into the plastic. If it's too difficult to turn the plastic, re-drill the hole a little larger. The metal screw will form the threads partially by cutting the plastic, and partially by forcing some of the plastic into shape--that's why you can get away with drilling the hole a little over-sized.
In a pinch, you might find a plastic metric-sized nut with a hole of
*almost* the correct diameter, and force it over the screw so that new threads are formed. I think these are usually nylon. Check your local Radio Shack (you might call them "Tandy") or hardware store.Other sources of 1/4"-20 fasteners might be old American-made items that people have stored away...something like an old radio or toy. (More recent ones were probably made in Korea or China, and it's a crap-shoot whether they'd have inch or metric fasteners.)
Oddly, with screws and nuts that as sized as fractions of an inch, we refer to them as "English." Since metric screws are sized by how many mm each thread is separated, the equivalent of 20 threads per inch is a pitch of
1.27 mm, and a 1/4" diameter is 6.35 mm. Maybe that info will help you find a nylon nut in a close size, as suggested above.
You're right actually. The shop had nothing auitable.
But my own trusty toolbox revealed three of them. :-) I'm pleased! I have no idea where I might have got them from though.
From what Roger posted to this thread thse may be UNC instead (Roger didn't say what size UNC but it seems they are a passable lookalike). Maybe a 1/4" Whitworth matches a 1/4" UNC. Is that correct?
On Sun, 30 Apr 2006 09:52:47 +0100, Andy had this to say:
More or less. The pitch is the same but the thread form is a little different. The UNC "near equivalent" is 1/4" - 20.
There is a slight thread profile difference which shouldn't matter on this sort of application. I'd be wary of using UNC into an aluminium camera body, though. Just my prejudice...
Unified nuts have linked circles stamped onto the face. Bolts have a circular depression in the centre of the head.
lookalike).
1/4" Whit and 1/4" UNC differ only in the included thread angle and crest / root rounding. Whitworth threads are 55 degrees and UNC are 60 degrees. In most (non precision applications) they are interchangeable.AWEM
Yes - it certainly true for 1/4". It seems to be generally true for other sizes too - except I've just looked at a table which gives 1/2" Whitworth as
12TPI but 1/2" UNC as 13TPI - so I'm not sure whether one of those is a misprint!
No, it's not a misprint.
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