John Rumm wrote:
Phil Addison wrote:
On Sat, 22 Aug 2009 08:58:44 +0100, "Dave Plowman (News)"
wrote:

In article ,
Dave Baker wrote:
After 30 years of engineering and accumulating hundreds of tools,
thread
gauges are something I've never felt a pressing need for. Provided you
have an accurate steel rule or preferably a digital vernier and know a
few basic facts it's pretty easy to identify most threads. Even if
diameter and pitch are similar you always have thread angle to help
distinguish types. Occam's Razor says that most threads you'll come
across in anything modern are metric so it's best to check for those
first.
[snip]

Thanks for a very useful article, Dave - I've learnt quite a bit from
it.
One for the FAQ?

Seconded

Sorted:

http://wiki.diyfaq.org.uk/index.php?...fying_a_thread


I must have missed the original thread or I would have spoken up at the
time as I think the quote below is more than a little misleading

"Once you've ruled out metric then the job gets easier. Imperial threads
don't generally have variants. UNC is the standard imperial coarse and
UNF the standard imperial fine. On old machinery you might come across
Whitworth which is an early coarse or its fine equivalent BSF."

I wouldn't class UN threads as Imperial. While I don't care a toss about
upsetting the Merkins I think they had a bigger hand in that
introduction that the Brits.

On old British machinery Whitworth was the norm. My first socket set
bought in 1964 was both AF and Whitworth and I think Whitworth could
still be found on some cars actually manufactured in the 1960s although
my car at the time was a 1952 Riley 2.5 and memory fades (or at least my
does) as to what was or was not current after such a long time.

Oh yes and BSP is of course a Whitworth thread.

I won't attempt to edit the FAQ. Someone is bound to object to my
intervention on principle so I leave it to others to correct should they
think it important enough.