A self-contained module for actuating an element of an earth-boring tool comprises a drive unit configured to be coupled to at least one actuatable element of the earth-boring tool. The drive unit is configured to be disposed at least partially within a compartment of a body of the earth-boring tool. The compartment is radially decentralized within the earth-boring tool. The drive unit includes a drive element configured to be coupled to the at least one actuatable element. The drive unit is configured to move the drive element in a manner moving the at least one actuatable element from a first position to a second position in a direction having a component parallel with a longitudinal axis of the earth-boring tool. The self-contained module is configured to be repeatedly attached to and detached from the earth-boring tool. Such a module may be attached to a tool body carrying extendable elements to form an earth-boring tool for borehole enlargement or stabilization within an enlarged section of the borehole.

A downhole cutting apparatus includes a cutter block. The cutter block includes a formation facing surface with cutting elements coupled thereto. The cutting elements are arranged in rows that may extend at an angle across a width of the formation facing surface. Mud flutes may optionally be located between rows of cutting elements. A gauge portion of the formation facing surface may be adjacent a leading edge having reinforcement members coupled thereto.

A downhole cutting apparatus includes a cutter block. The cutter block includes a formation facing surface with cutting elements coupled thereto. The cutting elements are arranged such that at least one cutting element has a different exposure relative to the formation facing surface than at least one other cutting element. In some embodiments, a row of cutting elements may have a gradually changing exposure. The exposure may change such that cutting elements nearer the gauge of the cutter block have less exposure than cutting elements farther from the gauge of the cutter block. In additional embodiments, an underreamer may include multiple cutter blocks. The cutter blocks may each have a different configuration in a backreaming portion, gauge portion, underreaming portion, any part thereof, or in a combination of the foregoing.

Rotatable elements for use with earth-boring tools include a movable element and a stationary element. The movable element and stationary element include an index positioning feature that is configured to rotate the movable element as the movable element moves between a first axial position and a second axial position.

A self-contained module for actuating an element of an earth-boring tool comprises a drive unit configured to be coupled to at least one actuatable element of the earth-boring tool. The drive unit is configured to be disposed at least partially within a compartment of a body of the earth-boring tool. The compartment is radially decentralized within the earth-boring tool. The drive unit includes a drive element configured to be coupled to the at least one actuatable element. The drive unit is configured to move the drive element in a manner moving the at least one actuatable element from a first position to a second position in a direction having a component parallel with a longitudinal axis of the earth-boring tool. The self-contained module is configured to be repeatedly attached to and detached from the earth-boring tool. Such a module may be attached to a tool body carrying extendable elements to form an earth-boring tool for borehole enlargement or stabilization within an enlarged section of the borehole.

A downhole cutting tool which may be a reamer or a mill has a rotary tool body with at least one block which carries hard-faced cutters and projects or is extensible from the tool body. A radially outward facing part of the cutter block defines a channel for fluid flow which extends generally axially along the cutter block. The channel is configured such that at least the rotationally trailing edge of the channel extends along the block in one or more directions which are inclined relative to the tool axis. This reduces or avoids the amount of channel edge parallel to the tool axis and thereby mitigates whirling and/or or vibration.

Drilling dysfunction during simultaneous down-hole drilling and reaming is reduced by obtaining an indication of force on cutters of a reamer, determining whether or not the indication indicates an excessive force, and upon determining that the indication indicates an excessive force, extending drag elements from the bottom hole assembly to contact a wall of the well bore and reduce the force on the cutters of the reamer. The indication of force on the cutters can be obtained by sensing the weight on the drill bit, and the determination can be done by comparing the indicated weight on the drill bit to a first threshold and a second threshold.

An expandable diameter drill bit includes a cutting blade having receiving and contacting ends, the receiving end having a pivot shaft and the contacting end having a tip. A drill bit includes a drill head body having an upper attachment portion and a lower body portion, the lower body portion defining a blade opening for receiving the receiving end of the cutting blade and a bolt receiving hole on opposing sides transverse the blade opening. The drill bit includes a torsion spring, a first blade leg, and a second body leg. The blade bolt passes through the bolt receiving holes and the pivot shaft and secured with a set screw. The first blade leg is coupled to the cutting blade with a spring retainer bolt, the second body leg is coupled to the drill head body, and the torsion spring biases the blade outwardly from the drill head body.

A cutting tool (1) for widening the diameter of a borehole and method thereof is disclosed. The cutting tool (1) comprises a housing (2) having cavity (10) in which a moveable activation element (6) is arranged. The activation element (6) is moved in an axial direction and is connected to one or more cutting blocks via a mechanical coupling (15). The mechanical coupling (15) transfers the axial movement of the action element into a radial movement of the cutting blocks. An activation unit (24) pushes the activation element (6) towards a stopping position which in turn causes the cutting blocks (11) to move out of the housing. The activation unit (24) further pulls the activation element back towards its starting position which in turn causes the cutting blocks to move back into the housing. The cutting blocks (11) extend into one or more cavities formed in the activation element, thereby increasing the travel-to-expansion ratio. The cutting blocks can be replaced by stabiliser blades (20) which are used to stabilise the drilling in the expanded borehole.

A under reamer that has two arms and is piston activated. The under reamer arms are supported on both side walls by a pin assembly. The under reamer arms are extended outward by a piston assembly which is spring biased to retract the arms. A surface of the under reamer arms adjacent the pivot point is protected via a holder assembly with a surface that matches the surface of the arms adjacent the pivot assembly.