Some Experiments on the Influence of Various Factors on Drill Performance

Abstract

Abstract The experiments described in this paper are part of a series of investigations to obtain basic data needed for improving drilling techniques in a number of engineering factories. The main criteria of drill performance and some of the principal factors which influence performance are discussed. Special attention is given to drill shape, and particularly to those elements, such as relief angle, point angle, relative lip height, and so on, which can be controlled by the drill user. The theory of self-regenerative vibration in drilling is discussed, and theories are developed to explain inaccuracies in hole size and alignment. The paper includes test results which tend to support these theories. Reference is made to those considerations of drill geometry and specification which entered into the investigations. The influence of the drilling machine on drill performance was discussed in a previous paper by the author.