British Threads - British Standard Brass
BRITISH STANDARD BRASS
BRASS THREADS (British Standard Brass) Because brass tubing has a uniform wall thickness, irrespective of the tube diameter, any thread cut on, (or in) it, would have to have the same depth, so 26 tpi is standard on all diameters. An example would be the thread cut on the brass trumpet horns of the 30s cars, although many were die-cast rather than brass. If it were 1" O/D, the thread would be 1" Brass, 26tpi.
BSB has a 26 TPI pitch through the whole range and is often confused with BS Cycle thread the difference being that brass thread has an angle of 55 degrees whereas Cycle is 60 degrees. Brass threads are usually confined to fittings and adjusters on cables. Brass thread taps and dies are sold and advertised as 26 tpi and are identified by the letters BSB.
These are a special order item.
Brass Pipe Screw Threads (Whitworth Form 55 Deg Thread Angle)
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| Thread Form Data | Tapping Hole | |||||||
| Diameter | O/D | Core | Pitch | Depth | Radius | Effective Dia | T.P.I | Dec / Met / Frac |
| 1/8" | 0.125 | 0.0757 | 0.03846 | 0.0246 | -- | 0.1020 | 26 | Number 47 |
| 1/4" | 0.250 | 0.2007 | 0.03846 | 0.0246 | -- | 0.2254 | 26 | Number 6 |
| 3/8" | 0.375 | 0.3257 | 0.03846 | 0.0246 | -- | 0.3504 | 26 | Letter Q |
| 1/2" | 0.500 | 0.4507 | 0.03846 | 0.0246 | -- | 0.4754 | 26 | 29/64" |
| 5/8" | 0.625 | 0.5657 | 0.03846 | 0.0246 | -- | 0.6004 | 26 | 37/64" |
| 3/4" | 0.750 | 0.7007 | 0.03846 | 0.0246 | -- | 0.7254 | 26 | 45/64" |
| 7/8" | 0.875 | 0.8257 | 0.03846 | 0.0246 | -- | 0.8504 | 26 | 53/64" |
| 1" | 1.000 | 0.9507 | 0.03846 | 0.0246 | -- | 0.9754 | 26 | 61/64" |
| 1-1/8" | 1.125 | 1.0757 | 0.03846 | 0.0246 | -- | 1.1004 | 26 | 1-5/64" |
| 1-1/4" | 1.250 | 1.2007 | 0.03846 | 0.0246 | -- | 1.2254 | 26 | 1-13/64" |
| 1-1/2" | 1.500 | 1.4507 | 0.03846 | 0.0246 | -- | 1.4754 | 26 | 1-29/64" |