This is the second paper describing the ‘Max’ rock breaker. In the preceding part I, early experiments and the theory of the rock-breaking process were described. This report continues with a description of experiments made with a model unit (hole diameter 6.7 mm) to investigate the behaviour of the device in various geometries (tunnelling, stoping, and quarrying). It then describes the design and testing of two larger machines, to fit holes of 35 and 57 mm diameter, respectively. The former of these machines was intended as a hand-held unit, while the latter was boom-mounted and provided with the means of drilling its own hole. Experiments with the model showed that even if very much confined, the rock could be extracted satisfactorily, and in geometries of low confinement, this could be accomplished with high efficiency. In concrete-breaking, no problems were encountered in breaking the concrete itself but, if present in a three-dimensional array, the reinforcing bars could cause trouble. Tests with the largest machine confirmed its ability to deal with rock at full scale, whether hard, soft, or badly fissured, and suggest the possibility of making a variety of very flexible and environmentally attractive mining machines.
Physics of fusion pumped lasers