A directional boring head assembly having a directional boring head, with a deflection surface capable of steering the directional boring head, combined with a replaceable cutting member is provided. The position of the cutting member relative to the deflection surface permits the directional boring head to steer the boring machine along the desired path while providing enhanced cutting action adaptable to different soil types. As the boring machine is advanced with rotation, the leading edge of the cutting member contacts only a small portion of the perimeter of the borehole thereby increasing the contact stress between the cutting member and the face of the borehole for more aggressive cutting action in hard ground conditions. Additionally, the directional boring head is provided with a pocket adapted to conform to the cutting member. The pocket engages the cutting member so that the cutting member fits snugly within the directional boring head thereby increasing the stability of the cutting member within the directional boring head. The cutting member may be replaced to simplify maintenance and to accommodate a variety of soil conditions. The directional boring head and the cutting member function together to maximize the cutting and steering capabilities of the directional boring head assembly while maintaining the integrity of the overall structure.

A frustum cutting bit arrangement, including a shank portion for mounting in, and to be retained by, a rotary cutting tool body, the shank portion having an axis, an inner axial end, and an outer axial end. A head portion has an axis coincident with the shank portion axis, a front axial end, and a rear axial end, the rear end coupled to the shank portion outer end, and the front end having a conical cavity therein diminishing in diameter from the front end toward the rear end. A frustum cutting insert has an axis coincident with the head portion axis, a forward axial end, a back axial end, and an outer conical surface diminishing in diameter from the forward end toward the back end, the conical cavity and the outer conical surface having substantially the same taper, the frustum cutting insert fitting into the cavity in a taper lock. In variations of the basic invention, the head portion may be rotatable with respect to the shank portion, the frustum cutting insert may comprise a rotating cutter therein, and combinations of such features may be provided for different applications.

A drill bit has a pair of cutting teeth with cutting elements extending from a cutting end portion of the drill bit. Each cutting tooth extends radially, outwardly parallel to a longitudinal axis of the drill steel. The cutting teeth are juxtaposed with one another on the longitudinal axis. Each cutting tooth includes a plurality of raised cutting elements connected to a plurality of lowered edge portions. The cutting elements produce concentric circular channels in the working surface of a rock formation, as the drill bit rotates during the cutting operation. The drill bit also includes a pocket for accumulating and removing dislodged material during the cutting operation.

A cutting tool (200, 202) has a longitudinally extending shaft portion (208) with a chucking part (204) and a cutting head (206). A cutting edge (220) is formed on the cutting head (206). The cutting edge (220) includes at least one cutting portion. A rake surface (224) is formed adjacent to at least one of the cutting portions (220) with the rake face being at a rake angle in the range from about -10.degree. to about 10.degree.. A clearance face (226) is formed adjacent to the at least one cutting portion opposite the rake face (224). The clearance face (226) is at a clearance angle in the range from about 10.degree. to about 50.degree.. An edge radius between the rake face and the clearance face is at a radius of from about 0.0003 to about 0.0040 inch.

An improved cutting insert cartridge arrangement for quick and easy mounting of cutting inserts to and removal from a rotary cutting tool, comprising a cutting insert receiver for the cutting insert, the insert receiver itself being quickly and easily removed from the rotary cutting tool body. The cutting insert receiver may have an outer end portion with an opening therein for receiving a cutting insert, the outer end portion being configurable to apply a varying lateral grasping force against an inserted cutting insert. The cutting insert receiver may be frusto conical in shape to mate with a complementary frusto conical recess in the rotary cutting tool body, whereby securing the receiver in the recess serves to apply the lateral grasping force against an inserted cutting insert due to the camming action between the mating surfaces of the two frusto conical members. Alternatively, a movable holder for holding the insert receiver may be coupled to the cutting insert receiver and slidable axially relative thereto to configure the outer end portion to increase grasping holding force against an inserted cutting insert in a first axial position of the movable holder, and to diminish grasping holding force against an inserted cutting insert in a second axial position of the movable holder.