A tap and chaser are provided each having a cylindrical tool receiver connected to a threading section by a shaft. The receiver and shaft are of diameters sufficiently small to enter the bore hole and distribute any off axis load onto a number of internal threads of the bore hole to dissipate loading. The threaded section includes a group of longitudinal flutes. Each of the lands of the threaded section includes a novel cutting face, tooth angle and rake angle to advantageously allow for threading deep blind holes.

A tap and chaser are provided each having a cylindrical tool receiver connected to a threading section by a shaft. The receiver and shaft are of diameters sufficiently small to enter the bore hole and distribute any off axis load onto a number of internal threads of the bore hole to dissipate loading. The threaded section includes a group of longitudinal flutes. Each of the lands of the threaded section includes a novel cutting face, tooth angle and rake angle to advantageously allow for threading deep blind holes.

A thread-cutting tap includes: a thread portion having an external thread, and including a chamfered portion and a complete thread portion that is axially adjacent to the chamfered portion; a flute extending from an axially distal end of the tap toward an axially proximal end of the tap; a rake face defined by one of widthwise opposite end portions of the flute; and a cutting edge defined by one of widthwise opposite edges of the flute, so as to be adjacent to the rake face and extend along the flute. The cutting edge is provided with a protrusion portion at least in a radially outer end portion of the chamfered portion, such that the protrusion portion protrudes from the rake face forwardly in the rotation direction and extends along the cutting edge.

A tool for generating a threaded hole is rotatable in a rotational movement about a tool axis extending through the tool, and is movable in an axial forward direction axially of the tool axis. The tool comprises at least one thread generation area and at least one drilling area, which are rigidly motion-coupled to each other. The drilling area is provided for generating a core hole and is arranged axially offset to the tool axis with respect to the thread generation area. The thread generation area projects radially to the tool axis, runs along a helical line, and a predetermined winding sense of the thread to be generated, and has a working profile which corresponds to the thread profile of the thread to be generated. The drilling area has a drilling edge, and at least one chip divider is arranged on the drilling edge, interrupts the drilling edge.

A process of forming a fastener with improved threading to resist multi-axial forces and off-axis loading scenarios is provided. The process may include placing first and second mill tools adjacent a shaft of the fastener having a proximal end and a distal end, rotating the shaft and the first and second mill tools, and translating the first and second mill tools along at least part of a length of the shaft to form: a first concave undercut surface oriented toward the proximal end, a first convex undercut surface oriented toward the distal end, a second concave undercut surface oriented toward the distal end, and a second convex undercut surface oriented toward the proximal end.

A fastener with improved threading for resisting multi-axial forces and off-axis loading scenarios is provided. The fastener may include a shaft and a plurality of helical threads disposed about the shaft. The plurality of helical threads may include a first helical thread and a second helical thread adjacent the first helical thread. The first helical thread may include a first concave undercut surface and a first convex undercut surface. The second helical thread may include a second concave undercut surface and a second convex undercut surface. When the fastener is viewed in section along a plane intersecting a longitudinal axis of the shaft, the first concave undercut surface and the second convex undercut surface may be oriented toward the proximal end of the shaft, and the first convex undercut surface and the second concave undercut surface may be oriented toward the distal end of the shaft.

A tap 1 has a threaded portion 2 including a cutting blade 5 on an outer circumferential surface, a flute portion 3 that divides the threaded portion 2 in a circumferential direction, and a shank portion 4 formed continuously from the threaded portion 2 and the flute portion 3 along a central axis O. The flute portion 3 includes, in a cross-sectional view, a first flute 31 formed continuously from the cutting blade 5 of the threaded portion 2, a second flute 32 formed continuously from the first flute 31, and a ridge line portion 33 being a boundary between the first and second flutes 31, 32. A distance “e” from the central axis O to the ridge line portion 33 is longer than a distance d1 and a distance d2, respectively.

A tap and chaser are provided each having a cylindrical tool receiver connected to a threading section by a shaft. The receiver and shaft are of diameters sufficiently small to enter the bore hole and distribute any off axis load onto a number of internal threads of the bore hole to dissipate loading. The threaded section includes a group of longitudinal flutes. Each of the lands of the threaded section includes a novel cutting face, tooth angle and rake angle to advantageously allow for threading deep blind holes.

A spiral flute tap includes a body having an axial forward end and an axial rearward end. The body has a cylindrical shank portion adjacent the axial rearward end, a threaded fluted portion adjacent the axial forward end, a non-threaded fluted portion between the cylindrical shank portion and the threaded fluted portion, and a central, longitudinal axis. The spiral flute tap further includes a plurality of helical flutes formed at a helix angle, HA, with respect to the central, longitudinal axis of the tap that continuously increases in magnitude in the threaded fluted portion. In other words, the lead of the plurality of helical flutes continuously decreases in magnitude in a rearward direction for a predetermined distance. In one example, the helix angle, HA, varies at a rate of between 0.5 degrees/mm to 4.0 degrees/mm. A method of making the spiral flute tap is also disclosed.

A pipe-tapered-thread machining tap has a thread, four spiral flutes and four cutting edges that include a plurality of thread intersection portions at each of which a corresponding one of the four cutting edges intersects with the thread. The thread intersection portions of the cutting edges have four groups, such that each of the four groups has ones of the thread intersection portions that are portions of a corresponding one of the four cutting edges. Every two of the thread intersection portions of each of the four groups is removed, such that, in each of the four groups, at least one of the thread intersection portions that is removed and at least another one of the thread intersection portions that is not removed are alternately arranged in a direction in which a corresponding one of the four cutting edges extends.