A device for measuring drill rod and drill hole orientations

Accuracy in drilling holes for explosives can be of considerable importance in the excavation of hard rock. It is particularly important in presplit blasting where final results cannot be better than the drilling allows. Traditional methods, using angled templates and spirit level, have largely been replaced by bubble and pendulum inclinometers; transducer or optical alignment gauges are also becoming common. Most however have shortcomings when precise alignment or a measurement of orientation, rather than just a setting or measure of dip, is required. The report describes a new drill orientation device which does not have these shortcomings and is simple and versatile, having an accuracy adequate for most surface excavations where precision drillng is required and a repeatability well within the requirements for presplitting. (A)