On Apr 4, 23:29, Chad Fernandez wrote: 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