A drill bit for use in forming holes in a printed circuit board (PCB) is disclosed. The drill bit includes a drill bit body having: a drill bit tip at a first end of the drill bit body; a flute winding about the drill bit body in a helix, wherein a helix angle of the flute is between 44 and 46 degrees in the vicinity of the first end and increases with increasing distance from the first end to between 49 and 51 degrees; and a land width of between 0.08 and 0.1 millimeters.

A cutting tool is configured to cut and countersink a hole in a workpiece. The cutting tool includes a shank and a fluted body extending along an axis. The body includes a tip, a chamfer in an axially spaced relationship with the tip and a cross hole with a proximal end opening to the chamfer. The body has a cutting section extending between the tip and the chamfer, and a countersinking section extending along the chamfer. At the cutting section, the body includes at least one hole-cutting edge. At the countersinking section, the body includes a scalloped countersink-cutting edge along a junction of the chamfer and the proximal and of the cross hole.

A drill bit for use in forming holes in a printed circuit board (PCB) is disclosed. The drill bit includes a drill bit body having: a drill bit tip at a first end of the drill bit body; a flute winding about the drill bit body in a helix, wherein a helix angle of the flute is between 44 and 46 degrees in the vicinity of the first end and increases with increasing distance from the first end to between 49 and 51 degrees; and a land width of between 0.08 and 0.1 millimeters.

The combination tool (2), in particular a drilling/chamfering tool, comprises a drill (6) extending in the longitudinal direction (4) with a clamping sleeve (8), which is designed to receive the drill (6) and fasten the drill (6) at a variable length and which has a holding seat (38) for a cutting insert (12). The drill (6) comprises a cutting region (22) provided with grooves (14), wherein the grooves (14) extend helically and are formed between two grooves (14) drill backs (18). At least one of the drill backs (18) is partially flattened to form an adjustment surface (16) for the cutting insert (12), wherein the adjustment surface (16) extends helically. As a result, a length adjustment over a large length range is made possible independently of the twist angle ().

A blade section has two lands and two flutes in an alternating manner and also has a linear chisel edge. The lands are each provided with: a margin section that is continuous with a cutting blade; a clearance section that is continuous with the margin section and that has a smaller diameter than the margin section; and a pad that is continuous with the clearance section and that has the same width as the width of the margin section.

A method is specified for producing a rotary tool (2) having a base body (4), which extends in a longitudinal direction (L) and in which at least one flute (6) is ground in by grinding in a first partial flute (12A) with a first helix angle (W1) in a first grinding step and by subsequently grinding in a second partial flute (12B) with a second helix angle (W2) in a second grinding step, the second helix angle differing from the first helix angle (W1) so that a flute (6) that expands in the longitudinal direction (L) is formed, wherein the two partial flutes (12A, 12B) are ground in using the same grinding wheel (11). In this way, a particularly quick production is realized. Furthermore, a corresponding rotary tool (2) is specified.

The invention relates to a rock drill comprising an insertion portion, a flute adjoined to the insertion portion, and a head portion adjoined to the flute, wherein the flute is of at least double-spiral configuration and correspondingly has at least two substantially spiral discharge grooves, to which respectively two substantially spiral flute webs forming the lateral groove walls are assigned. It is proposed that a constant spiral pitch is assigned to the first discharge groove, inclusive of the lateral groove walls thereof, along the drill longitudinal axis, and that at least one of the two flute webs assigned to the first discharge groove has or have along the drill longitudinal axis, at least in sections, a web spine width which changes, in particular, alternately.

A twist drill for drilling composite materials includes a shank; a drill body; a drill tip having a cutting edge, a chisel edge, and a secondary chisel edge, wherein the secondary chisel angle of the drill tip is 145 to 165 and the point angle is 70 to 100; and a flute extending from the drill tip to the drill body. The flute has a constant helix, and the helix angle of the flute being selected from the range 45 to 55. A method of drilling a composite material comprising fibers uses the twist drill of the present embodiment. Suitably, the composite material is carbon fiber reinforced plastic or glass fiber reinforced plastic, and optionally being a laminate material such that the method comprises stack drilling. Embodiments achieve a combination of good hole quality, good tool life and good hole size spread.

A twist drill has a shaft and a flute portion, which extends between a drill tip and the shaft and has at least two flutes, which run helically around it at an angle of twist, are separated from one another by two webs and have a land extending between the flutes on the circumference of the flute portion. In order to provide a twist drill that has the features mentioned at the beginning, has better lubrication of the round bevels, less wear, improved guidance and improved concentricity, at least two round bevels that are spaced apart from one another are provided on each land and extend on the land at an angle of inclination in relation to the drill axis that is greater than the angle of twist but less than 90.

A chip discharging flute is formed in a tip outer peripheral portion of a drill body rotated around an axis in a drill rotation direction. A cutting edge is formed in an intersection ridgeline portion between a wall surface of the chip discharging flute facing the drill rotation direction and a tip flank. The cutting edge includes a main cutting edge portion extending from an inner peripheral side toward an outer peripheral side of the drill body, and a cutting edge shoulder portion extending from an outer peripheral end of the main cutting edge portion to an outer periphery of the drill body, and is subjected to honing. Compared to the outer peripheral end of the main cutting edge portion, in an outer peripheral end of the cutting edge shoulder portion, a true rake angle is increased on a negative rake angle side, and a size of the honing decreases.