A thread series used in watchmaking in Switzerland, 19ᵗʰ – 20ᵗʰ centuries. According to de Carle, “the most popular modern Swiss screw thread.” As is obvious from the table below, the size number is the diameter in tenths of a millimeter. Thread angle, 50 degrees; depth of thread, 0.8 pitch. Depth of rounding, 0.093 × pitch; radius, 0.0732 × pitch.
The company sold ready-made screws, and issued a screw plate as a means of checking sizes. Much of the use of the series occurred when makers found it convenient to thread their own screws using the screwplate as a die.
Number | Diameter, millimeters |
Pitch, millimeters |
---|---|---|
4 | 0.40 | 0.100 |
4½ | 0.45 | 0.100 |
5 | 0.50 | 0.125 |
5½ | 0.55 | 0.125 |
6 | 0.60 | 0.150 |
6½ | 0.65 | 0.150 |
7 | 0.70 | 0.175 |
7½ | 0.75 | 0.175 |
8 | 0.80 | 0.200 |
8½ | 0.85 | 0.200 |
9 | 0.90 | 0.225 |
9½ | 0.95 | 0.225 |
10 | 1.00 | 0.250 |
11 | 1.10 | 0.275 |
12 | 1.20 | 0.300 |
13 | 1.30 | 0.325 |
14 | 1.40 | 0.350 |
15 | 1.50 | 0.375 |
16 | 1.60 | 0.32 or 0.457 |
17 | 1.70 | 0.34 or 0.486 |
18 | 1.80 | 0.36 or 0.514 |
19 | 1.90 | 0.38 or 0.543 |
20 | 2.00 | 0.40 or 0.571 |
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Last revised: 3 January 2011.