English: Screws with different thread types. From left to right
Metric M12, 40 mm long left turning thread
Metric M12, 40 mm long (ISO 4017, Strength 8.8))
Metric Fine M12x1.5, 40mm long
Metric Fine M12x1.25, 40mm long (ISO 8676, Strength 8.8)
United thread Standard Fine UNF 1/2 inch, 1.5 inch long (Strength Grade 5 ( ~ 8.8 ). Dimensions in metric would be 12.7mm by 38.1mm)
United thread Standard Coarse UNC 1/2 inch, 1.5 inch long (Strength Grade 5 ( ~ 8.8 ). Dimensions in metric would be 12.7mm by 38.1mm)
British Standard Whitworth BSW 1/2 inch, 1.5 inch long. (Dimensions in metric would be 12.7mm by 38.1mm)
British Standard Whitworth Fine BSF 1/2 inch, 1.5 inch long. (Dimensions in metric would be 12.7mm by 38.1mm)
All screws with hex bolt heads, although they also differ slightly in size depending on the standard. Update from File:Different Thread Types.jpg with two more threads. The BSF is slightly photo shopped, since the bolt was longer
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