Drills, Taps and Dies

Drilling true and correctly dimensioned holes and cutting accurate threads are basic requirements in all engineering work, but as in all areas of engineering, new materials and new techniques lead to alterations in standards. Many of these are primarily concerned with production engineering and are well documented, but others affect the quite different: the discontinuation of ‘number’ drills and the phasing out of cycle threads. The currently book written with the small user in mind is appare…