Nick Müller wrote:
yourname wrote:


it is correct to say it is metric, since the thread pitches are metric


They arent metric. Look in the standard and you will only find pitches
of 0.2; 0.25; 0.35; 0.5; 0.75; 1; 1.25; 1.5; 2; ...

But BA has pitches of 1.0, 0.9, 0.81, 0.73
Next difference are the 47.5 degrees in contrast to the 60 degrees for
metric threads.

Sorry, but you should look into the standards before spreading such
missinformation.

Nick

Perhaps YOU should look at the standards. BA #0, pitch .03937, major
diameter .2362 hmmm what the **** do you think that is?

It was apparently based on the Thury thread, a swiss system, which was,
you guessed it, metric. all the dimensions are in inch units because
thats what the British machinists could measure. It is not an ISO thread
and never was, but it is most certainly 'metric'

Your position is the same as saying that a 1/4-29 thread is not an
'inch' thread. It is not UNC or UNF, but it is most certainly 'inch'


ref:

http://www.britishfasteners.com/threads/