Underreamer having splined torque transmitting connection between telescoping portions for control of cutter position

An angular position and weight actuated underreamer comprising:

• longitudinally telescoping and relatively rotatable upper and lower portions connectable respectively to an upper drill string and a lower drill string;
• first and second connector parts, one carried with each of said telescoping portions, each connector part comprising a plurality of grooves longitudinally extending and longitudinally staggered in length, a plurality of keys longitudinally extending and longitudinally staggered in length with at least one such key in between adjacent grooves, said connector parts providing first and second engaged positions therebetween for transmitting torque between said telescoping portions, said connector parts providing a different angular position and a different longitudinal position for the telescoping portions in each said position;
• a plurality of cutter arms;
• means for pivotally mounting the cutter arms on said lower telescoping portion;
• and
• a cam on said upper telescoping portion operative when moved longitudinally towards said first position for moving the cutter arms relatively outward towards an extended underreaming position, the cutter arms being retracted relatively inwardly to a clearance position when said connector parts are in said second engaged position.

An angular position and weight actuated underreamer comprising:

• longitudinally telescoping and relatively rotatable inner and outer portions connectable respectively to an upper drill string and a lower drill string;
• a splined connection between said telescoping portions comprising a plurality of grooves and keys on each telescoping portion, the grooves and keys on the telescoping portion being engageable and disengageable with respectively keys and grooves in the outer telescoping portion, said grooves being relatively staggered longitudinally and said keys being relatively staggered longitudinally on each telescoping portion thereby providing first and second engaged positions for the splined connection, both positions for transmitting torque between the telescoping portions, said splined connection providing a different angular and a different longitudinal position for the telescoping portions in each said position;
• a plurality of cutter arms;
• means for pivotally mounting the cutter arms on said outer telescoping portion;
• and
• means on said inner telescoping portion for urging the cutter arms relatively outward toward an extended underreaming position when said splined connection is in said first position, the cutter arms being retracted relatively inwardly to a clearance position when said splined connection is in second position.

An underreamer comprising:

• longitudinally telescoping and relatively rotatable upper and lower portions connectable respectively to an upper drill string and a lower drill string;
• first and second connector parts, one carried by each said telescoping portion, each said connector part comprising a plurality of grooves of staggered length and a plurality of keys of staggered length, the grooves and keys of one connector part being engageable and disengageable with, respectively, the keys and grooves of the other connector part said connector parts having first and second engaged positions, both positions for transmitting torque between the telescoping portions, said connector parts providing a different angular and a different longitudinal position for the telescoping portions in each said position;
• means for pivotally mounting at least one cutter arm on one of said telescoping portions;
• and
• means for urging such at least one cutter arm relatively outward from the telescoping portions to an extended underreaming position when said connector parts are in said first position, said cutter arm being capable of retraction to an inward position when said connector parts are in said second position.