On the evolution of drill-bit shapes

Abstract Drilling tools play important roles in woodworking, metalworking, mining and quarrying. The markedly different physical properties of wood, metal and rock have largely influenced the variety of tool shapes and different techniques employed for drilling these materials. From the wide range of shapes four groups can be segregated, viz. semi-cylindrical, flat, helical and hollow, dictated in part by the tool materials and manufacturing facilities available to producers. All users have experienced problems of procuring, servicing and manipulating drilling tools. The present study is devoted to an examination of the evolution of the basic shapes of drill bits and offers a hypothesis which unifies them.