The invention relates to a tool holder on a drill transmission for tubular drilling tools having at least two different diameters, wherein the holder is equipped with a hollow-cylindrical recess and with at least one radially oriented locking bolt which is installed in the wall of the hollow-cylindrical recess and which engages in a corresponding opening in the drilling tool, wherein there is at least one further hollow-cylindrical recess which is complementary to one of the different drilling tools.

A hole saw having a blade portion separable into two parts which when separated form a base portion and a tip portion. The base and the tip have correspondingly shaped apertures and lugs that co-operate together to hold the blade tip in place. A locking means further assists in ensuring that the blade tip remains locked to the base and includes a sliding latch that engages an aperture in the blade and the base and is itself locked in place to thereby lock the blade to the base. An intermediate portion also allows for the hole saw to drill through different depths.

Hole-saws are provided herein, and more specifically to hole-saw assemblies and processes having adjustable platters for multiple simultaneous saw components, optional elimination of a guide drill, and the ability to retrieve cores of a sawed work piece before sawing completely through the workpiece. One hole-saw device, may have a motive force; a base plate rotatable by the motive force; cutters; and locking mechanisms to mount the base plate to the cutters.

Drill bit (20) including a drilling shaft and a cutting portion having a first drilling segment (23-1) and a second drilling segment (23-2). The first drilling segment (23-1) has a first inner lateral surface (28-1) with a first inner distance (B.sub.1(, h)), and the second drilling segment (23-2) has a second inner lateral surface (28-2) with a second inner distance (B.sub.2(, h)) from the longitudinal axis (24) of the drilling shaft. The first inner distance (B.sub.1(, h)) varies between a first maximum value (B.sub.max,1) and a first minimum value (B.sub.min,1) over the circumference of the first drilling segment (23-1) and has precisely one first absolute minimum value (B.sub.min,1). The second inner distance (B.sub.2(, h)) is greater than or equal to the first absolute minimum value (B.sub.min,1) over the circumference of the second drilling segment (23-2).

Ring drill bit including a drilling shaft and a ring segment (22) which is fastened by an underside to an end face of the drilling shaft and which has an inner lateral surface (26). The inner lateral surface (26) has an inner distance (B(, h)) from the longitudinal axis (23) perpendicular to the longitudinal axis (23) of the drilling shaft. The inner distance (B(, h)) varies in the plane perpendicular to the longitudinal axis (23) and has a first minimum value (B.sub.min,1), a first maximum value (B.sub.max,1), a second minimum value (B.sub.min,2) and a second maximum value (B.sub.max,2).

A retractable pilot bit comprises a stem defining a rotational axis and configured to rotate in a first rotational direction about the rotational axis, a collar coupled to the stem and configured to rotate in the first rotational direction, and a bit configured to rotate in a first rotational direction in a penetrating configuration and configured to rotate in a second rotational direction opposite the first rotational direction in a rotatable configuration.

A drill bit which is rotatable about a drilling axis is disclosed. The drill bit has a cutting section having one or more cutting segments and a first plug-connecting element and a drill shaft section having a second plug-connecting element. The first plug-connecting element and the second plug-connecting element form a plug connection and the first plug-connecting element and the second plug-connecting element are connectable by a pin connection.

A hole saw assembly having a drive shaft, drive disk and hole saw blade. The drive disk has a plurality of radially extending projections that engage with engagement slots in the side of the hole saw blade.

A hole-saw comprises a cylindrical body, a plate, a mandrel, and a clamping member. A cutting edge is formed at an open end of the body and is disposed about the body's rotational axis. The plate is disposed at an opposite end of the body, is rotationally coupled to the body, and is oriented perpendicular to the body's rotational axis. In one embodiment the plate has lateral slots formed through the plate and lateral grooves formed in the plate's distal surface in an orientation transverse to the slots. The mandrel's proximal section forms an arbor shaft, and its distal section includes lateral bosses sized to insert through the plate's slots and rest in the plate's grooves. The clamping member has a body that is movable along the mandrel's longitudinal axis to engage the plate's proximal surface and clamp the plate between the clamping member and the bosses resting in the plate's grooves. Other embodiments include a cylindrical body with a cutting edge at both ends. Either cutting edge can have an inner or an outer tooth to easily remove the plug. The pilot drill bit can have a burr to prevent jamming.

A device for holding and securing a tool, in particular, a drill bit, on a machine tool, for example, a core drill, including an output shaft for transmitting a torque generated in the machine tool to the tool; and a union nut positioned around the output shaft for detachably connecting the output shaft to an attachment end of the tool.

The output shaft includes a locking ring and the union nut includes a washer disk, as well as an attenuator, the washer disk being positioned between the locking ring and the attenuator.