Patent ID: 7350596

Claim:
An apparatus for expanding a diameter of a borehole at a desired depth comprising: a pilot/anchor comprising a bellows having at least a first position in which said pilot/anchor is substantially disengaged from a borehole wall and a second position in which said pilot/anchor is substantially engaged with said borehole wall and, while in said second position, substantially prevents upward and downward movement of said pilot/anchor along a central axis of said borehole; a power transfer unit adapted for coupling with a drill string and operable to move in either an upward or downward direction along said central axis of said borehole; a central conduit extending between said pilot/anchor and said power transfer unit; and one or more flexible cutting elements coupled between said pilot/anchor and said power transfer unit, and arranged such that when said pilot/anchor is in said second position and said drill string bears downwardly on said power transfer unit, said power transfer unit moves downward within said borehole thereby deploying and locking said one or more cutting elements into position to remove material from said borehole wall, and when said drill string moves upwardly said power transfer unit moves upward within said borehole, thereby unlocking and retracting said one or more cutting elements.