Patent ID: 6976547

Claim:
An underreamer for forming a cavity from within a well bore, comprising: a housing adapted to be disposed within the well bore; an actuator partially slidably positioned in the housing, the actuator comprising a first portion, a second portion, and a stop member proximate an end of the actuator; wherein a cross-sectional area of the second portion is larger than a cross-sectional area of the first portion; at least one cutter set, each cutter set having a first end and a second end, the first end of each cutter set pivotally coupled to the housing, the second end of each cutter set pivotally coupled to a connector; wherein an axial force applied to the actuator is operable to slide the actuator relative to the housing causing the second portion of the actuator to contact each cutter set and extend each cutter set radially outward relative to the housing from a retracted position to a first position; and wherein the stop member is operable to contact the connector as the actuator slides relative to the housing to force the connector to slide relative to the housing during the application of the axial force, causing each cutter set to further extend radially outward relative to the housing from the first position to a second position.