A general purpose hole saw guide and a method of forming holes through surfaces, without the need of a centering bit, are provided. The hole saw guide includes a circular disk with concentric grooves on its surface. The disk is transparent and portable for placement on a surface through which a hole is to be drilled to facilitate the centering and stabilizing control of a hole saw on the surface. The method includes the steps of providing a transparent disk having concentric grooves; positioning the disk on a surface; mounting the disk to the surface; inserting a hole saw that is fitted to a drill into the grooves of the disk; drilling a hole through the disk and surface beneath it; and removing the disk from the surface after the hole has been drilled.

A cutting insert includes a top face, a bottom face and a plurality of side walls extending between the top face and the bottom face. A central axis of the cutting insert extends through the top face and the bottom face. A peripheral cutting edge is defined at the juncture of each side wall and the top face. Each cutting edge includes a linear cutting edge portion having an end portion that connects to a concave cutting edge portion that curves inwardly in a plane that is perpendicular to a first plane containing the central axis, wherein at least one linear cutting edge portion and its corresponding end portion are parallel to the first plane containing the central axis.

A hole cutter has a cylindrical blade body including a cutting edge and one or more axially-elongated apertures formed within a side wall of the blade body. The axially-elongated aperture is configured to receive a lever, such as a screwdriver, therethrough. Each axially-elongated aperture includes a first fulcrum axially spaced adjacent to the cutting edge, a second fulcrum axially spaced further away from the cutting edge than the first fulcrum, and optionally a third fulcrum axially spaced between the first and second fulcrums. A lever, such as a screwdriver, can be inserted into the aperture and placed against each of the fulcrums to lever slugs out of the interior of the blade body.

One example of the present disclosure relates to a coupon. The coupon includes a first surface with a first circular channel and a second surface opposite and parallel to the first surface. The second surface is spaced a distance D0 from the first surface and includes a second circular channel concentric with the first circular channel. The coupon also includes a toroidal portion between the first circular channel and the second circular channel. The toroidal portion includes a rectangular sectional portion.

A support assembly for a core drill uses an improved reinforcement. The reinforcement can include an extension extending between a center of the tool and a perimeter of the tool the extension can be a non-planar structure having a channel along a portion of the structure. The reinforcement can include a slanted element that can be associated with the extension, that can be formed monolithic with the extension, or otherwise combined with an extension. Multiple slanted elements can be used to form an extension. A top plate can be included for strengthening the reinforcement.

A core cutter includes: a cylindrical body; and a tipped bit that is disposed in a manner to protrude from a distal end of the body. The core cutter is configured to cut a workpiece with the bit when the body is rotated about a rotational axis that is an axis of the body. At a distal end of the body, a notch is formed adjacently to the bit at a position forward of the bit in a rotation direction of the body. A width of the notch in a circumferential direction of the body at the distal end of the body is less than or equal to 1.0 mm.

A core cutter includes: a cylindrical body; and a tipped bit that is disposed in a manner to protrude from a distal end of the body. The core cutter is configured to cut a workpiece with the bit when the body is rotated about a rotational axis that is an axis of the body. At a distal end of the body, a notch is formed adjacently to the bit at a position forward of the bit in a rotation direction of the body. A width of the notch in a circumferential direction of the body at the distal end of the body is less than or equal to 1.0 mm.

The shank (12) of a disposable rotary cutting tool (10) comprises a pipe section (16) cut from a drawn metal pipe. The tool head (14) is formed from a cut-out (18a, 18b) of a drawn metal sheet or a section of a metal tube by non-cutting machining. The pipe section (16) and the tool head (14) are advantageously attached by force fitting.

The shank (12) of a disposable rotary cutting tool (10) comprises a pipe section (16) cut from a drawn metal pipe. The tool head (14) is formed from a cut-out (18a, 18b) of a drawn metal sheet or a section of a metal tube by non-cutting machining. The pipe section (16) and the tool head (14) are advantageously attached by force fitting.

The hole saw with threadably removable portion is an improved hole saw that includes a removable portion that is able to slide back and forth with respect to an outer drill bit. The outer drill bit includes internal threadings along an inner surface, which correspond with external threadings provided on an outer surface of the removable portion. When the hole saw has bored a hole into an object, a core remains inside of the outer drill bit. The rotation of the drill rotates the removable portion with respect to the outer drill bit in order to push the core out of the outer drill bit. The outer drill bit includes a shoulder, which works in concert with the removable portion so as to lock the components together when in use as a hole saw.