Methods of forming a drill bit or boring tool having a cutting edge that includes a pair of generally smooth curvilinear shaped portions that are positioned near the radial outer portions of the cutting edge and connected to one another by a pair of generally linear portions that traverse a longitudinal centerline of the tool.

A step drill bit has a cutting head defining a longitudinal axis and having a plurality of steps having different effective diameters. First and second cutting edges are formed in the cutting head. The first cutting edge and the second cutting edge are arranged such that the bit is asymmetric in a plane perpendicular to the longitudinal axis relative to a plane containing the longitudinal axis. A rubbing surface is formed on each step where the rubbing surface extends to approximately the effective diameter of that step such that the first cutting edge, second cutting edge and the rubbing surface forms three points of contact with the side wall of the hole being cut.

A power tool accessory includes a shank member having a first hardness. A conically-shaped body is coupled to the shank member and includes a series of stepped shoulders that increase in diameter from a tip portion to a base portion. A flute extends substantially from the tip portion to the base portion, with cutting edges defined at the intersection of the flute and the shoulders. The body has a second hardness greater than the first hardness.

A drill bit or boring tool having cutting edge that includes a pair of generally smooth curvilinear shaped portions that are positioned near the radial outer portions of the cutting edge and connected to one another by a pair of generally linear portions that traverse the longitudinal centerline of the tool.

A step drill bit can include a cutting head defining a longitudinal axis and multiple steps having different effective diameters. First and second cutting edges can be formed in the cutting head. The first cutting edge and the second cutting edge can be arranged such that the bit is asymmetric in a plane perpendicular to the longitudinal axis relative to a plane containing the longitudinal axis. The step drill bit can further include one or more flutes. Each flute can define a groove in the cutting head that extends along a helical path about the longitudinal axis. Each flute can have a variable helix angle such that the angle of the helix about the longitudinal axis changes at one or more points along the length of the flute.

One aspect of the disclosure relates to a cutting tool for forming a final opening in a stack that includes at least two layers and a pilot opening having a pilot-opening dimension and extending through at least one of the at least two layers. The cutting tool includes a shank. The cutting tool also includes a first portion including at least one of a first coating or the first coating and a second coating, wherein the first coating at least partially covers the first portion. The cutting tool also includes a second portion between the shank and the first portion, wherein the second portion includes the second coating, and wherein the second coating at least partially covers the second portion.

An adjustable drill has a drill body having a face surface with a directional feature provided therewith. At least one cartridge is mounted adjacent the face surface and selectively slidable along the directional feature to provide adjustment. At least one insert is releasably affixed in an insert pocket provided in the cartridge. In further examples, the adjustable drill may have a central cutting system in combination with the adjustable cartridge type system, wherein the central cutting system may be modular. There may also be provided a modular type of holder arrangement to provide flexibility to adapt the system for various applications.

A reamer includes a shank, a washer, a ring and a blade. The shank is a polygonal rod and includes an annular groove made in a periphery and a bore made in an end. The washer includes a slot. The ring includes a circular opening. The blade includes an insert inserted in the bore through the slot and the circular opening. The circular opening is made of a diameter larger than a width of the blade to allow the blade to rotate relative to the ring.

A drilling tool for producing drill holes includes a tip and a shaft arranged opposite the tip in a direction of a longitudinal axis of the drilling tool. The drilling tool has at least one geometrically defined cutting edge in the tip area, and has an expanded diameter trailing the tip in a longitudinal direction from the tip. The drilling tool has a first area with a first diameter that precedes the expanded diameter, and a second area with a second diameter, larger than the first diameter, that trails the expanded diameter. The drilling tool is distinguished in that the expanded diameter and/or the second area is/are embodied such that chips are produced in the area of the expanded diameter and/or in the second area when a workpiece is machined, chips consistent with those produced when a workpiece is machined with a geometrically undefined cutting edge.

A drill includes a substantially cylindrical cutting portion includes a first region located at a front end portion, and a second region which has a step whose diameter increases as going from the first region to a rear end in a sectional view perpendicular to a rotation axis, and which is continuous with the first region in an end of the second region on a side of the step, and using this drill, a method of manufacturing a machined product is provided.