A step drill bit includes a shank and a body having a proximal end adjacent the shank and a distal end opposite the proximal end. The body defines a plurality of axially stacked, progressively sized steps including a first step at the distal end, a terminal step at the proximal end, and a plurality of intermediate steps having incrementally increasing diameters disposed between the first and terminal steps. The step drill bit also includes a plurality of cutting edges each disposed along one of the plurality of steps. Each edge defines a helix angle and a radial rake angle. The radial rake angle and the helix angle of the cutting edge at the terminal step is greater than the radial rake angle and the helix angle of the cutting edge at the first step.

A twist drill and an exchangeable head for a twist drill, the twist drill extending along a central axis of rotation and having a front end formed as a drill point with two cutting edges and at least two clearance surfaces. Two helical chip flutes conduct chips away from the cutting edges. Each cutting edge extends in a transition between the clearance surfaces. One of the chip flutes extends from an inner position adjacent to the central axis to a peripheral envelope surface and has a main portion closest to the peripheral envelope surface. Each chip flute is delimited by a side surface including a main rake face, which extends rearward from the main portion of the cutting edge. The cutting edges are contained in an imaginary conical surface, such that the twist drill is operable to generate a bottom profile having the shape of an inverted cone.

A drill bit for forming a round hole in a workpiece, includes a cylindrical shank having a longitudinally extending fluted portion with opposed first and second ends, and defining a longitudinal axis about which the shank is rotatable. The fluted portion includes opposed helical flutes formed in the cylindrical surface of the fluted portion of the shank and extending longitudinally along and between the first and second ends of the fluted portion. The helical flutes each define a concave surface intersecting with the cylindrical surface of the shank to form opposed flute edges. The first end of the fluted portion includes a cutting tip intersecting the helical flutes, wherein at least one of the flute edges has a concave cross-section extending from the second end toward the first end of the fluted portion.

A drill according to an embodiment includes a bar-shaped drill body extending along a rotation axis, a cutting edge located at a front end of the drill body, and a first flute extending spirally from the cutting edge toward a rear end of the drill body. The first flute includes a first region which is located close to the front end and has a helix angle θ1, and a second region which is located closer to the rear end than the first region and has a helix angle θ2 smaller than the helix angle θ1. The second region includes an elongated protruding part along the first flute.

The drill comprises a base body, which extends in the axial direction along an axis of rotation and rotates about the axis of rotation in a direction of rotation during operation. Into the base body are incorporated flutes and between consecutive flutes is formed a rear surface, which extends, in relation to the direction of rotation, from a leading flute to a trailing flute. On the rear surface in the region of the leading flute, a guide chamfer and a support chamfer spaced apart from it in the direction opposite the direction of rotation are formed, wherein the support chamfer, as radially outermost region, forms a support edge for a merely linear support.

A drill comprising: a drill main body; a chip discharge flute; and a tip cutting edge. The tip cutting edge includes: a first tip cutting edge which extends toward the axially posterior end as it goes toward the outside in a radial direction; and a second tip cutting edge which is disposed outside the first tip cutting edge in the radial direction. The second tip cutting edge extends toward the tip in the axis direction as it goes toward the outside in the radial direction or extends to be perpendicular to the axis. The radially inner end of the second tip cutting edge is disposed on the axially posterior end with respect to the radially outer end of the first tip cutting edge. The radially outer end of the second tip cutting edge is disposed on a virtual extension line of the first tip cutting edge.

An instrument comprising a shank and a working portion, the working portion having a tip and a plurality of flutes being defined by at least two lands having a land margin; wherein the working portion has a parabolic cross-section defining opposing convexed surfaces extending between at least two opposing land margins.

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 (γ).

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.

A rotary tool according to a non-limiting aspect includes a body having a rotation axis and extending from a first end to a second end. The body including: a first part including the first end; a second part located closer to a second end than the first part and having a larger outside diameter than the first part; a cutting edge located at a side of the first end; a ridge portion located in the first part and the second part, connected to the cutting edge and helically extending from the cutting edge toward the second end; and a flute located along the ridge portion. The flute includes: a first flute located at the first part and having a first helix angle; and a second flute located at the second part and having a second helix angle. The second helix angle is smaller than the first helix angle.