Re: The Duchess Project: 1940 Super 8 Convertible Sedan
Posted by HH56 On 2022/4/25 13:22:10
Part of the confusion on size may be that pipe and machine threads use a different standard.
Machine thread size ODs are approximately the actual measured dimension while pipe sizes go by the nominal inside diameter of the pipe rather than any outer dimension. I guess when they set the standard for pipe size threads the OD measurement had to include the 2 pipe wall thicknesses of a typical iron pipe.
In this case, the nominal OD for 1/8 pipe thread is .405 which is just slightly less than 7/16" and is why your machine thread die appears to fit the switch thread.
Attach file:
thread size.jpg (67.98 KB)
Machine thread size ODs are approximately the actual measured dimension while pipe sizes go by the nominal inside diameter of the pipe rather than any outer dimension. I guess when they set the standard for pipe size threads the OD measurement had to include the 2 pipe wall thicknesses of a typical iron pipe.
In this case, the nominal OD for 1/8 pipe thread is .405 which is just slightly less than 7/16" and is why your machine thread die appears to fit the switch thread.
Attach file:
thread size.jpg (67.98 KB)
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