Thury thread

Swiss Screw Thread

In 1876 the Socièté des Arts de Genève formed a committee to standardize small threads, Geneva being a center of the watch industry. In 1877 a conference was convened in Geneva, under the leadership of Professor Thury, to agree upon a thread series intended for instruments, clocks and watches.

The thread angle is 47.5°. Roots and crests are rounded with a radius of 0.2 times the pitch.

Gauge	Outer diameter, millimeters	Pitch mm
25	0.254	0.0718
24	0.289	0.0798
23	0.328	0.0886
22	0.372	0.0985
21	0.426	0.109
20	0.479	0.122
19	0.543	0.135
18	0.616	0.150
17	0.699	0.167
16	0.794	0.185
15	0.901	0.206
14	1.102	0.229
13	1.16	0.254
12	1.32	0.282
11	1.49	0.314
10	1.64	0.349
9	1.92	0.387
8	2.18	0.430
7	2.48	0.478
6	2.81	0.531
5	3.19	0.590
4	3.62	0.656
3	4.11	0.729
2	4.66	0.810
1	5.29	0.900
0	6.00	1.000
—1	6.81	1.11
—2	7.73	1.23
—3	8.77	1.37
—4	9.95	1.52
—5	11.3	1.69
—6	12.8	1.88
—7	14.5	2.09
—8	16.5	2.32
—9	18.7	2.58
—10	21.2	2.87
—11	24.1	3.19
—12	27.4	3.54
—13	31.0	3.93
—14	35.2	4.37
—15	40.0	4.86
—16	45.4	5.40
—17	51.5	6.00
—18	58.4	6.66
—19	66.3	7.40
—20	75.2	8.23

Marc Thury.
Systématique des vis horologères.
Geneva, 1878.