movement of an Elgin watch

Elgin screw threads

Like many watch companies, the Elgin National Watch Company developed a screw thread series specifically to meet their needs. This is not a thread series in the sense that, say, ISO threads are, as there is no consistent relationship between them.

“L” indicates a left-hand thread.

Threads
per inch
Diameter in
millimeters
360 0.33
320 0.37
260 0.42
220 0.52
260 0.57
220 0.62
180 0.67
220 0.72
180 0.77
220 0.77
140 0.92
220 0.92
120L 1.02
200 1.02
120 1.07
110 1.12
110 1.17
140 1.22
200 1.22
110L 1.27
180 1.37
110 1.52
110L 1.52
180L 1.77
110L 1.92
80L 1.93
80L 2.23

Source: Machinery, vol. 22 June 1916, page 890. The writer states the data was taken from “the Elgin material list issued in May, 1915.”

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