Drilling apparatus and cutter

摘要: An underreamer including a body having bore therethrough, an arm mounted at its upper end to the body, sleeve member detachably secured lower of each and adapted receive frictional wear caused by rotation conical cutter thereto. Bearings seals disposed between provide smooth cutter. In addition, locking pins bearings extending secure on arm. The arms are pivotally in slots mechanical structure is provided for moving their cutting position with ends positioned radially outward from body.