ABSTRACT
In evaluating the ways to improve waterjet performance, it became clear, early in the study of the process, that as the jet cut a deeper and deeper hole, that its efficiency was increasingly reduced by the energy required to overcome the power of the water leaving the hole. In the last chapter two ways were examined for overcoming this problem, one of which was to pulse the waterjet, the other to rotate the jet slightly off-axis [8.1]. However, i f when the jet was rotated it was also turned at an angle to the axis of rotation, then the jet would cut a path wide enough for the nozzle to feed into the rock. As the nozzle was moved forward, the waterjet would continue to cut a groove ahead of the pipe and this would continue until the jet had drilled a hole through the rock (Fig. 8.1).
