Dear every vendor of a tap and die set.
4-40 is a UNC thread, the 'C' means "coarse".
4-48 is the UNF or "fine" thread in the #4 size.
Your inclusion of a 4-40 in your "fine" thread tapping set is wrong.
4-40 is a UNC thread, the 'C' means "coarse".
4-48 is the UNF or "fine" thread in the #4 size.
Your inclusion of a 4-40 in your "fine" thread tapping set is wrong.
