OPTIMUM
M A S C H I N E N - G E R M A N Y
Operation
Version 1.0.1 dated 2015-05-27
Page 56
Original operating instructions
TU3008 | TU3008V
GB
4.18.2 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". Desig-
nation 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
Threads in 1"
Threads in 1"
BSW
BSF:
BSP/BSPT
BA-threads
[Inch]
mm
(R)
D. [mm]
No.
D
[mm]
55° Flank angle
47 1/2° Flank angle
1/16
1.588
60
-
-
16
134
0.79
3/32
2.382
48
-
-
15
121
0.9
1/8
3.175
40
-
28
9.73
14
110
1.0
5/32
3.970
32
-
-
-
13
102
1.2
3/16
4.763
24
32
-
-
12
90.9
1.3
7/32
5.556
24
28
-
-
11
87.9
1.5
1/4
6.350
20
26
19
13.16
10
72.6
1.7
9/32
7.142
20
26
-
-
9
65.1
1.9
5/16
7.938
18
22
-
-
8
59.1
2.2
3/8
9.525
16
20
19
16.66
7
52.9
2.5
7/16
11.113
14
18
-
-
6
47.9
2.8
1/2
12.700
12
16
14
20.96
5
43.0
3.2
9/16
14.288
12
16
-
-
4
38.5
3.6
5/8
15.875
11
14
14
22.91
3
34.8
4.1
11/16
17.463
11
14
-
-
2
31.4
4.7
3/4
19.051
10
12
14
26.44
1
28.2
5.3
13/16
20.638
10
12
-
-
0
25.3
6.0
