Siemens & Halske Thread

Siemens & Halske Thread was used in telephones approx. 1900 AD.
The flank angle ranges from 50° to 68°.

Thread No.	Major Diameter mm	Tapping Drill Size mm	Pitch mm	Thread Angle °
11	8.95	7.0	1.21	50
14	7.20	5.7	1.05	58
17	6.00	4.6	0.89	55
18	5.75	4.5	0.78	58
21	5.12	4.0	0.78	58
25	4.00	3.18	0.66	61
27	3.37	2.58	0.66	68
29	2.80	2.22	0.53	66
31	2.16	1.63	0.49	68
33	1.78	1.39	0.34	59
34	1.63	1.29	0.30	55
36	1.22	0.95	0.22	50