A method includes advancing a drill bit into a formation to form core sample pieces. The drill bit has a central axis and includes a crown defining an inner operative circumference. The crown is configured to form a core sample. A core receiving space is configured to receive the core sample as the drill bit is advanced into the formation. A base surface is spaced from the cutting face along the central axis of the drill bit. The base surface is configured to break apart portions of the core sample to form core sample pieces. The method can further include associating the core sample pieces with respective depths at which the core sample pieces were separated from the formation.

A cutting assembly for use in a drill bit has an ovoid insert including an ultrahard material. The ovoid insert is cast in a matrix such that the matrix surrounds at least part of the ovoid insert, limiting movement of the ovoid insert. Material is removed from the top surface and sidewall of the cutting assembly to produce a cutting edge.

A core drill is arranged to drill in the ground, the core drill having a sleeve with a first end portion and a bit ring which is detachably attached in a rotationally rigid manner to the first end portion, one of the sleeve and the bit ring having a groove with two converging side faces, and the other one of the sleeve and the groove having a protrusion with two complementary side faces, and the groove and the protrusion being arranged to engage with each other.

A core drill is arranged to drill in the ground, the core drill having a sleeve with a first end portion and a bit ring which is detachably attached in a rotationally rigid manner to the first end portion, one of the sleeve and the bit ring having a groove with two converging side faces, and the other one of the sleeve and the groove having a protrusion with two complementary side faces, and the groove and the protrusion being arranged to engage with each other.

A drill has a stationary drive mechanism coupled to a rotating drill, the rotating drill having a serpentine optical fiber positioned on an inner shell having a serpentine groove with fiber Bragg gratings (FBGs) coupled to the inner shell and arranged parallel to the central axis of rotation for measurement of axial forces and also positioned circumferentially for measurement of drill torque. The FBGs are arranged on a single optical fiber and coupled to a broadband optical source such that reflected optical energy is directed to an interrogator for estimate of strain at each FBG. The FBG responses may also be examined dynamically to estimate material hardness during a drilling operation.

A drill has a stationary drive mechanism coupled to a rotating drill, the rotating drill having a serpentine optical fiber positioned on an inner shell having a serpentine groove with fiber Bragg gratings (FBGs) coupled to the inner shell and arranged parallel to the central axis of rotation for measurement of axial forces and also positioned circumferentially for measurement of drill torque. The FBGs are arranged on a single optical fiber and coupled to a broadband optical source such that reflected optical energy is directed to an interrogator for estimate of strain at each FBG. The FBG responses may also be examined dynamically to estimate material hardness during a drilling operation.

Drilling tools, such as drill bits, having a shank, a crown, and a plurality of abrasive cutting elements. In the case of impregnated drilling tools, the abrasive cutting elements are dispersed throughout at least a portion of the crown. In the case of surface-set drilling tools, the abrasive cutting media is secured to and projects from a cutting face of the crown. The matrix of the crown of the drilling tools includes a carbide-forming alloy that forms a direct carbide bond with at least one cutting element of the plurality of abrasive cutting elements.

Drilling tools, such as drill bits, having a shank, a crown, and a plurality of abrasive cutting elements. In the case of impregnated drilling tools, the abrasive cutting elements are dispersed throughout at least a portion of the crown. In the case of surface-set drilling tools, the abrasive cutting media is secured to and projects from a cutting face of the crown. The matrix of the crown of the drilling tools includes a carbide-forming alloy that forms a direct carbide bond with at least one cutting element of the plurality of abrasive cutting elements.

A modular rotary claw drill bit having a head is mountable at a body, the head mounting a plurality of front and gauge cutting picks. A cutting tip of each front pick is located at a different radial position at the head to optimise the flushing of cut material and to minimise pick wear during use.

A hard composite composition may comprise a binder and a polymodal blend of matrix powder. The polymodal blend of matrix powder may have at least one first local maxima at a particle size of about 0.5 nm to about 30 m, at least one second local maxima at a particle size of about 200 m to about 10 mm, and at least one local minima between a particle size of about 30 m to about 200 m that has a value that is less than the first local maxima.