However the thread angles are different, Whit and BSF are 55 degrees and ANC/UNC/NC etc are 60 degreesVarious sizes of UNC are similar to whitworth.some sizes are comparable and some are not. From memory 1/2" is one of the sizes that do not like each other.
However the thread angles are different, Whit and BSF are 55 degrees and ANC/UNC/NC etc are 60 degrees