Specifically those old style glass telegraph line type insulators. The threads they fit on (usually on wood pins back in the old days) are spec'd as 1 inch threads. But does anyone have a link to an actual thread specification. I want to turn some of these on a lathe, so I'll need to know depth (shape is square), pitch, inside and outside diameter.
I have an old glass insulator which I was showing to a lineman doing repairs near my house. He rummaged around and found a wood pin like the one you're looking for. He gave it to me and it's an exact fit in the insulator.
The threads are are on the first 2 inches of a cone 1 inch diameter at the end and 1 5/8 inches diameter 4 5/8 inches from the end. The pin is then reduced to a 4 3/8 inch long cylinder 1 1/2 inch in diameter. The whole thing is 9 inches long. They're 8 threads in the first 2 inches and the flat bottomed v-grooves between threads are about 3/32 inch deep with the thread tops about 1/8 inch wide.
You beat me to it, I was going to offer the specs from a metal pin I have (from a circa 1930s 7200V distribution circuit) and it has the same specs.
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