On Apr 4, 23:29, Chad Fernandez wrote:
> I've read about bolt types on Brit bikes a bit. It seems that they had
> a variety of things they called Whitworth.
Not really. See Tony's post; there are various series that use the same
Whitworth thread form (55 degree thread angle, and rounding of crests and
troughs) but they have different names. BSW (British Standard Whitworth)
is the standard coarse series, analagous to ANC/UNC. BSF (British Standard
Fine) is the corresponding fine-pitch series, analagous to ANF/UNF.
There are some special-purpose threads you might have come across, such as
BSB (British Standard Brass) which is used for finer pitch on soft metals
(26 tpi, regardless of diameter). BSP (BS Pipe) is used for some pipe
fittings, and is confusing because the sizes refer to the internal
diameters of the high-pressure pipes or glands it would be used for (so
1/4" BSP is a little over 1/2" diameter over the threads). To add insult
to injury, there are two types: plain, and tapered. Then there are some ME
(Model Engineeer) threads which are very fine pitch, in two standard
series: 32 tpi, and 40 tpi. A few of these correspond to normal
BSW/BSF/BSB threads, but apart from that, they're relatively rare. Rarer
still is British Standard Cycle, a fine pitch thread with a 60 degree
thread angle, mostly 26 tpi or 32 tpi (1/8" is 40 tpi, though).
--
Pete Peter Turnbull
Network Manager
University of York
Received on Fri Apr 05 2002 - 02:17:05 BST