Provided is a fastening structure having a wide application range and a high degree of freedom of design. A fastening structure includes: a head including a first end surface and a first screw part formed on the first end surface; and a shank including a second end surface and a second screw part formed on the second end surface and threadedly engaging with the first screw part. The first end surface includes a first principal surface oriented in an axial direction of the first screw part and a first step surface oriented in a rotational direction of the first screw part. The second end surface includes a second principal surface oriented in an axial direction of the second screw part and a second step surface oriented in a rotational direction of the second screw part. The first and second principal surfaces face each other and the first and second step surfaces face each other when the first screw part threadedly engages with the second screw part.

A drill bit with chamfering function has a body, a chamfering blade, an abutting rod, an elastic element, an adjusting element, and a drill bit. The body is a hollow tube, and has an internal space, a blade opening, a pivot segment, and a connecting end. The chamfering blade is pivotally connected to the body, selectively extends out of the blade opening, and has a blade portion, a blade pivot portion, and an abutting portion. The abutting rod is disposed in the internal space and abuts against the abutting portion. The elastic element is disposed in the internal space and is compressed between the abutting rod and the adjusting element. The adjusting element is disposed in the internal space for adjusting an amount of compression of the elastic element. The drill bit is securely connected to the connecting end of the body.

A rotary cutting tool with a shank and an interchangeable cutting tip, wherein the shank includes a pocket which receives the interchangeable cutting tip via an interference fit. The pocket includes two centering wall portions which, when viewed along a central longitudinal axis, are oriented at a first angle with respect to one another, the first angle being greater than zero. The interchangeable cutting tip is axially displaceable between: an initial position, assumed upon being received in the pocket of the shank; a clamped position, wherein the interchangeable cutting tip is fixedly held with respect to the shank; and a bump-off position, wherein the interchangeable cutting tip is not fixedly held. A holding element holds the interchangeable cutting tip in the clamped position, and a spring assembly which displaces the interchangeable cutting tip between the clamped position and the bump-off position. Other variants and embodiments are broadly contemplated herein.

A drill tip may include a first part and a second part. The first part includes a cutting edge located at a side of a first end, and a recess located at a side of a second end, where the first end is one side of a central axis and the second end is another side of the central axis. The second part includes a shank portion extending along the central axis, and an engaging portion which connects to the shank portion at a side of the first end and includes a diameter greater than the shank portion. The engaging portion is located in the recess.

A rotary cutting tool with enhanced bump-off capability is disclosed. The cutting tool includes a tool shank having a pocket. A replaceable cutting head is at least partially disposed within the pocket of the tool shank with an interference fit. A coupling pin assembly is at least partially received within a bore of the tool shank. The coupling pin assembly comprises a sleeve member and a coupling pin at least partially disposed within the sleeve member. The sleeve member includes an upper portion and a lower portion having a non-circular cross-sectional shape with a bump-off surface. An actuation screw contacts the coupling pin assembly and causes the replaceable cutting head to move relative to the tool shank. The bump-off surface of the lower portion of the sleeve member extends radially outward with respect to the coupling pin by a distance, D, thereby providing enhanced bump-off capability.

A drill including: a chip discharge groove formed in an outer periphery of an edge portion serving as a leading end side portion of a drill body; and a cutting edge formed in an intersecting edge between a rake surface of a leading end side region and a leading end flank of the edge portion. The drill having a margin portion, a shoulder portion and a web thinning portion. The cutting edge includes, in order from a rotation center, first cutting edge, second cutting edge, shoulder cutting edge, and margin cutting edge portions. Honing widths of the second cutting edge, the margin cutting edge, and the shoulder cutting edge portions satisfy a relation represented by expression (1), as follows: honing width of the shoulder cutting edge portion>honing width of the margin cutting edge portionhoning width of the second cutting edge portion.

A tool for machining materials has a main part and one or more blades. The main part is made of a low-alloy steel. The socket is welded to the main part, and the blade edges are made of a hard metal. The hard metal contains at least 82 vol. % of tungsten carbide and a metallic binder made of a cobalt-nickel-based alloy. The hardness of the hard metal is greater than 1350 HV10. The socket has a sintered composite, and 40 vol. % to 60 vol. % of the composite is composed of a metal carbide and a metallic binder. At least 95 vol. % of the metallic binder is made of nickel, and the hardness of the composite is less than 800 HV10.

A hole saw arbor with mechanically automated plug removal to automatically remove the center plug of debris following drilling with the hole saw. A slidable collar is placed in an upper position on a threaded shaft to drill with the hole saw, and slid to a lower position on the threaded shaft for automated function of an ejection plate to rise within the hole saw to slowly eject a plug of removed material.

An accessory tool includes an adapter end having a maximum outer dimension, and a shank coupled to the adapter end. The shank includes a tool engagement portion including a cross section having a maximum outer width, a first reduced portion disposed between the tool engagement portion and the adapter end and having a first minimum outer dimension and a first length, and a second reduced portion formed in the tool engagement portion between the first reduced portion and an end of the shank. The second reduced portion is engaged by the tool to secure the shank to the tool, and has a second minimum outer dimension and a second length. The maximum outer dimension is greater than the maximum outer width. The maximum outer width is greater than the first minimum outer dimension and greater the second minimum outer dimension. The first length is greater than the second length.

A modular rotary cutting tool for conducting cutting operations on a work piece is described. The modular rotary cutting tool includes a tool shank having a pocket and a cutting head replaceably mounted in the pocket of the tool shank. The cutting head has a leading end and trailing end opposite the leading end. The drilling portion extends from the leading end of the modular rotary cutting tool to the reaming portion. The reaming portion extends from the drilling portion to a coupling portion of the cutting head. The coupling portion extends from the reaming portion to the trailing end of the cutting head.