DRILL SHOE

摘要

Drill shoe A drill shoe adapted to fit onto a drill pipe of external diameter de and internal diameter di comprises an externally stepped cutting surface comprising a plurality of steps, the diameters of the steps increasing as they progress away from the tip of the shoe. The maximum external diameter De of the shoe is greater than the external diameter de of the drill pipe. The shoe also comprises an internal, substantially cylindrical, inner surface of diameter Di, Di being less than the internal diameter di of the drill pipe. The shoe is suitable for use in a vibratory drill string for obtaining cores from unconsolidated geological formations, such as soil, sand and gravel or similar materials.