Abstract

Apparatus for drilling a large diameter hole in the surface of a material includes an upper body; a lower body rotatably connected to the upper body; a motor for rotating the lower body relative to the upper body; cutting discs, connected to the lower body for cutting the material and moving the material toward a casing; the casing, extending through the upper and lower bodies, for receiving the cuttings from the cutting disk and carrying the cuttings through the bodies; and an engagement assembly for limiting downward travel of the casing and the bodies so that the casing is securable in a preselected position of downward travel and is removable through the upper side of the upper body. The engagement assembly engages the casing with the lower body so that the casing is rotated with the lower body. An auger having a hollow interior can be provided at the lower end of the casing. The casing and auger can be removed through the top of the apparatus and a conventional drill string and drill bit can be passed therethrough.