Abstract: The present disclosure relates to an underreamer. In one aspect, the underreamer comprises a body, the body comprising at least one pocket therein, the underreamer further comprising at least one cutter secured with respect to the body, at least one actuating mechanism for moving the cutter between a retracted position in the pocket, and an extended position in which only the cutter projects from the body. In one aspect, the or each actuating mechanism comprises a piston for driving extension of the cutter, and a linkage to a cutter arm with respect to which the cutter is mounted, and a return spring for biasing the cutter to the retracted position.

Abstract: The present disclosure relates to an underreamer. In one aspect, the underreamer comprises a body, the body comprising at least one pocket therein, the underreamer further comprising at least one cutter secured with respect to the body, at least one actuating mechanism for moving the cutter between a retracted position in the pocket, and an extended position in which only the cutter projects from the body. In one aspect, the or each actuating mechanism comprises a piston for driving extension of the cutter, and a linkage to a cutter arm with respect to which the cutter is mounted, and a return spring for biasing the cutter to the retracted position.

Abstract: This invention relates to a ground drilling or cutting tool comprising a cutting element removably attached thereto by attachment means, the tool further including retention means adapted to maintain attachment of the cutting element to the tool in the event that the attachment means fails. The retention means comprises a first surface on a side of the cutting element, a mounting recess in the cutting tool in which at least a portion of said cutting element locates, a second surface in a side of the mounting recess against which said first surface locates, channels in each of said first and second surfaces that align so as to cooperatively define a dowel hole when said first and second surfaces locate together, at least one dowel that locates in the dowel hole, and means for retaining the or each dowel within the dowel hole.

Abstract: This invention relates to a ground drilling or cutting tool comprising a cutting element removably attached thereto by attachment means, the tool further including retention means adapted to maintain attachment of the cutting element to the tool in the event that the attachment means fails. The retention means comprises a first surface on a side of the cutting element, a mounting recess in the cutting tool in which at least a portion of said cutting element locates, a second surface in a side of the mounting recess against which said first surface locates, channels in each of said first and second surfaces that align so as to cooperatively define a dowel hole when said first and second surfaces locate together, at least one dowel that locates in the dowel hole, and means for retaining the or each dowel within the dowel hole.

Abstract: This invention describes a reaming tool (10) for attachment to a drill string having a body (12) that has connection means (14a, 14b) at either end for attachment to a drill string, at least one roller reamer (16) rotatably mounted to the body (12), and at least one channel (18) extending on the body positioned to intersect with the roller reamer (16). This ensures that flushing fluid flow is directed to each roller reamer (16).

Abstract: The invention is an attachment means for a ground drilling or cutting tool (10) that enables cutting elements (11) to be removably secured to the tool (10). The attachment means include a first surface (13) on the cutting element (11), a second surface (14) on the tool (10) upon which the first surface (11) locates, dowel holes (15) in each of the first and second surfaces, dowels (16) that locate in aligned dowel holes between said surfaces, engagement surfaces (17, 18) on the cutting element and tool that extends substantially parallel to the longitudinal axis of the tool and engage to resist side loads applied to the cutting elements (11) and fastening means (19) that secures the cutting elements (11) to the tool (10). The invention provides a means of easily removing the cutting elements (11) from the tool (10) for either replacement or maintenance work.

Abstract: This invention describes a reaming tool (10) for attachment to a drill string having a body (12) that has connection means (14a, 14b) at either end for attachment to a drill string, at least one roller reamer (16) rotatably mounted to the body (12), and at least one channel (18) extending on the body positioned to intersect with the roller reamer (16). This ensures that flushing fluid flow is directed to each roller reamer (16).

Abstract: The invention is an attachment means for a ground drilling or cutting tool (10) that enables cutting elements (11) to be removably secured to the tool (10). The attachment means include a first surface (13) on the cutting element (11), a second surface (14) on the tool (10) upon which the first surface (11) locates, dowel holes (15) in each of the first and second surfaces, dowels (16) that locate in aligned dowel holes between said surfaces, engagement surfaces (17, 18) on the cutting element and tool that extends substantially parallel to the longitudinal axis of the tool and engage to resist side loads applied to the cutting elements (11) and fastening means (19) that secures the cutting elements (11) to the tool (10). The invention provides a means of easily removing the cutting elements (11) from the tool (10) for either replacement or maintenance work.

Abstract: A diamond insert for a rotary drag bit consists of an insert stud body that forms a first base end and a second cutter end. The cutter end of the insert is formed in a convex or spherical shape of polycrystalline diamond material. The convex layer of diamond is oriented relative to an axis of the stud body with a negative rake angle from 0.degree. to about 45.degree. inclusive.

Abstract: A mechanism is disclosed for rock bits whereby cutting elements, rotatably mounted to fixtures with journals, are constantly forced to rotate or precess by the interaction of the earth formation and the cutter. The cutters are fixed in skewed or offset positions on a cutting face of a rotary drill bit head. These cutting elements act as drag or shear cutters when they are operated in an earth formation.