English bolt dimensions to Metric bolt dimensions

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English bolt dimensions to Metric bolt dimensions

Postby R_Wood » Wed Aug 10, 2005 1:13 am

Trying to find out how to convert pitch threads on english bolts to metric and vice versa

Postby Guest » Wed Aug 10, 2005 3:43 am

English bolts are threads per inch. The pitch, or inches per thread is the inverse of that.

Metric is millimeters per thread.

Since 1" = 25.4 mm, if you divide 25.4 by the threads per inch, you'll get the pitch in mm.

As an example, a 1/4-20 bolt has a 25.4/20 = 1.27 mm thread pitch (which would not be a standard metric thread). Standard metric bolts and screws have well defined rules for diameter and thread pitch.

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