The term “Odex” stands for Overburden Drilling EXcentric, a drilling method effective for boring through boulders and rock strata. In this method, a specialized heavy-duty drill string is lowered into a steel casing. As drilling starts, the Odex drill bit cuts ahead of the casing, allowing wings on the bit to open and create a hole slightly larger than the casing. The drill bit’s shoulder contacts a shoe inside the casing, enabling simultaneous hammering down of the casing. High-pressure air is released through flushing holes in the drill bit, pushing the cuttings back up the casing .