Rotary cutting tools are disclosed comprising shanks and replaceable cutting inserts are provided. A head of the cutting insert includes insert centering surfaces that contact the pocket centering walls of the shank, and insert drive surfaces that contact the torque transmitting pocket drive walls of the shank. The configurations and sizes of the shank and cutting insert features are controlled to provide improved torque transmission, rigidity and stability during operation of the rotary cutting tools.

A drill head includes a first attachment surface attached to a holder, a head tip surface opposite to the first attachment surface in an axial direction along the central axis, and a head outer peripheral surface continuous with the first attachment surface and the head tip surface. The head outer peripheral surface is provided with a first flute and a second flute extending helically about the central axis from the head tip surface to reach the first attachment surface. The first flute and the second flute are symmetric with respect to the central axis. Each of the first flute and the second flute has a first end and a second end that face each other with a space between them in a circumferential direction along a circumference centered on the central axis.

A cemented carbide consisting of: a hard phase consisting of tungsten carbide grains; and a binder phase comprising cobalt, wherein a content of the hard phase in the cemented carbide is 91.5 to 97 mass %, a content of the cobalt in the cemented carbide is 3 to 8.5 mass %, the hard phase has an average grain size of 0.15 to 0.50 m, the binder phase has an average grain size of 0.10 to 0.25 m, in a histogram showing a grain size distribution of the hard phase, a number N1 is 7 to 10, wherein N1 is the number of classes having a frequency of 50% or more of the maximum frequency Fmax, the classes are 0.05 m intervals, and the binder phase has a ratio of a 10% cumulative grain size D10 to a 90% cumulative grain size D90 on area basis, D10/D90, of 0.23 or more.

A ring bit comprises an annular or cylindrical shape. The ring bit is configured to be provided around a pilot bit at a distal end of a drilling tool concentrically with the pilot bit. The ring bit comprises at least one protrusion protruding inwards from a first surface provided inside the ring bit, and at least one ring bit pulling surface, which ring bit pulling surface is formed in the protrusion and formed in relation to a radial direction of the ring bit in a direction of a longitudinal axis of the drilling tool in such a manner that a first length of the protrusion at the first surface in the direction of the longitudinal axis is greater than a second length of the protrusion at a second surface. The second surface is defined by the inner-most surface of the protrusion and the first surface is provided at the base of the protrusion on the pulling surface side of the protrusion.

A drill bit (10) for hand-guided drilling of a blind hole with a blind hole diameter and a blind hole depth into a metal workpiece, including a shank (20) which defines a drilling direction (30) and has an axis of rotation oriented in the drilling direction, wherein the shank has a cutting edge (50) at its end pointing in the drilling direction and has a stop shoulder (55) at a distance from the cutting edge defining the blind hole depth and measured counter to the drilling direction, wherein the cutting edge defines the blind hole diameter by rotation about the axis of rotation, wherein the shank has an enveloping circle diameter that changes along the axis of rotation and is larger at the stop shoulder than the blind hole diameter, wherein the shank has a first shank section (40) which adjoins the stop shoulder counter to the drilling direction and which reaches up to the stop shoulder and in which the enveloping circle diameter, starting from the stop shoulder, increases counter to the drilling direction.

A metal cutting drill insert for a drill tool has opposing top and bottom surfaces with a symmetry axis extending therebetween. At least one stepped cutting edge is configured to cut a continuous chip along the at least one stepped cutting edge. The at least one stepped cutting edge is formed at an intersection of a rake face and an adjoining clearance face of the side surface. In a top view facing the top surface the at least one stepped cutting edge includes a step formed by a transitional edge between a first part and a second part edge. The step extends in a radial direction relative the symmetry axis by a first distance h1, and in a side view facing the side surface the step extends in a direction from the bottom surface towards the top surface by a second distance h2, wherein 0.8.Math.h1h21.2.Math.h1.

A cutting insert for a modular rotary cutting tool is disclosed. The cutting insert may include a shaft, opposing insert centering surfaces, and convex torque transmission insert drive surfaces.