Core drill piloting system

A pilot tool assembly for a core drill comprises a pilot tool unit that fits within the core drill and expandable means engagable with the interior surface of the core drill for releasably locking the pilot tool unit to the core drill, the pilot tool assembly being removable from the core drill by application of an axial force to the pilot tool unit. The pilot tool unit comprises a pilot tool that projects from the front end of the core drill and serves as a centering aid for the core drill. The pilot tool may be inserted into a predrilled pilot hole whereby to keep the core drill centered on a desired location. The pilot tool may be a small diameter drill that is used to drill the pilot hole.