British Thread (55° Flank Angle) - Optimum OPTI turn TU 3008G Operating Manual

4.19.2 British thread (55° flank angle)
BSW (Ww.): British Standard Withworth Coarse Thread Series is the most common coarse
thread in Great Britain and corresponds in its usage category to the metric coarse-pitch thread.
The designation of a hexagon head screw 1/4" - 20 BSW x 3/4" , is here: . 1/4" is the nominal
diameter of the screw and 20 is the number of threads in 1" of length
BSF: British Standard Fine Thread Series. British Standard Fine Thread Series. BSW- and BSF
are the thread selection for the common screws. This fine thread is very common in the British
machine tool industry, but it is replaced by the American UNF thread.
BSP (R): British Standard Pipe Thread. Cylindric pipe thread; designation in Germany: R 1/4"
(nominal width of the tube in inch). Tube threads are larger in their diameter as "BSW".
Designation 1/8" - 28 BSP
BSPT: BSPT: British Standard Pipe - Taper Thread. Conic tube thread, cone 1:16; designation:
1/4" - 19 BSPT
BA: BA: British Association Standard Thread (47 1/2° flank angle). Common with instruments
and watches, is being replaced by the metric ISO thread and by the ISO miniature thread. It
consists of numeric designations from 25 to 0=6.0 mm max diameter.
Table of the British threads
Nominal diameter of
the thread
Inch mm
1/16 1.588
3/32 2.382
1/8 3.175
5/32 3.970
3/16 4.763
7/32 5.556
1/4 6.350
9/32 7.142
5/16 7.938
3/8 9.525
7/16 11.113
1/2 12.700
9/16 14.288
5/8 15.875
11/16 17.463
3/4 19.051
13/16 20.638
Operation
Version 1.1.6 - 2021-9-17
Threads in 1"
BSW BSF: BSP/BSPT
(R)
55° Flank angle
60 - -
48 - -
40 - 28
32 - -
24 32 -
24 28 -
20 26 19
20 26 -
18 22 -
16 20 19
14 18 -
12 16 14
12 16 -
11 14 14
11 14 -
10 12 14
10 12 -
Translation of original instruction
Threads in 1"
BA-threads
D. [mm] No.
47 1/2° Flank angle
16 134
15 121
9.73 14 110
- 13 102
- 12 90.9
- 11 87.9
13.16 10 72.6
- 9 65.1
- 8 59.1
16.66 7 52.9
- 6 47.9
20.96 5 43.0
- 4 38.5
22.91 3 34.8
- 2 31.4
26.44 1 28.2
- 0 25.3
D.
[mm]
0.79
0.9
1.0
1.2
1.3
1.5
1.7
1.9
2.2
2.5
2.8
3.2
3.6
4.1
4.7
5.3
6.0
TU3008G GB
49