Patent ID: 7484578

Claim:
An apparatus for drilling holes in a substrate with a drive motor comprising: a mandrel having an upper end portion, a lower anchoring end portion attachable to the substrate, and a smooth cylindrical intermediate outer surface therebetween; a hollow drive shaft disposed axially about the mandrel and engageable to the drive motor for rotating the drive shaft under power of the drive motor, the hollow drive shaft having a lower end portion; at least one bearing mounted to the hollow drive shaft and seated on the smooth outer surface of the mandrel for permitting rotational and longitudinal movement between the mandrel and drive shaft, whereby said drive shaft is rotatable on the smooth outer surface of the mandrel and is independently movable longitudinally relative to the mandrel; a hollow, tubular core drill bit attached to the lower end portion of said drive shaft which the drill bit has a lower cutting edge; and an expansion anchor mechanism located at the lower end of the mandrel for attaching the mandrel lower anchoring end portion to the substrate.