The invention relates to a core drill with an end portion (3) and a drill bit portion (1-2). The end portion and the drill bit portion are joinable in a watertight fashion with a sealing element (11). The sealing element (11) is provided in a space between the end portion and the drill bit portion, such that it is being compressed in a sealing fashion when the end portion and the drill bit portion are joined. The end portion and the drill bit portion are locked together with a joining element (8, 10) which achieves this locking effect when moves in the radial direction of the core drill. When the joining element moves in this direction, the end portion and the drill bit portion move towards each other. Thus the sealing element is being compressed while concurrently the end portion and the drill bit portion are joined together. This is further achieved without the joining element having to extend in the axial direction of the core drill. Typically, the joining element (8, 10) is constituted by a set screw.

A hole cutter has a substantially cylindrical blade body defining a blade body circumference, a cutting edge formed on one end of the blade body, and an axially-elongated slot formed through the substantially cylindrical blade body. The axially-elongated slot is configured to receive chips flowing from the cutting edge within the interior of the blade body and (i) into the slot, and/or (ii) through the slot, to prevent the collection of such chips within the interior of the blade body and/or at an interface between the blade body and work piece. The axially-elongated slot defines a first end adjacent to the cutting edge, a second end axially spaced further from the cutting edge, and a slot area. The hole cutter further defines a total slot area to blade body circumference ratio within the range of about 0.1 to about 0.3 depending on the size of the hole cutter.

A hole cutter has a substantially cylindrical blade body defining a blade body circumference, a cutting edge formed on one end of the blade body, and an axially-elongated slot formed through the substantially cylindrical blade body. The axially-elongated slot is configured to receive chips flowing from the cutting edge within the interior of the blade body and (i) into the slot, and/or (ii) through the slot, to prevent the collection of such chips within the interior of the blade body and/or at an interface between the blade body and work piece. The axially-elongated slot defines a first end adjacent to the cutting edge, a second end axially spaced further from the cutting edge, and a slot area. The hole cutter further defines a total slot area to blade body circumference ratio within the range of about 0.1 to about 0.3 depending on the size of the hole cutter.

A hole cutter can include a cylindrical blade body with a cutting edge and one or more axially-elongated apertures. Each axially-elongated aperture can include a first fulcrum axially spaced from the cutting edge, and a second fulcrum axially spaced further away from the cutting edge than the first fulcrum. The blade body can also include a third fulcrum defined by a second aperture different from the one or more axially-elongated apertures. The third fulcrum may be spaced closer to the cutting than the first and second fulcrums. A lever, such as a screw driver, can be inserted into the apertures and placed against each of the fulcrums to lever slugs out of the interior of the blade body. The third fulcrum may alternatively be defined by another axially-elongated aperture that is located a different distance from the cutting edge than the axially-elongated aperture containing the first and second fulcrums.

A hole cutter can include a cylindrical blade body with a cutting edge and one or more axially-elongated apertures. Each axially-elongated aperture can include a first fulcrum axially spaced from the cutting edge, and a second fulcrum axially spaced further away from the cutting edge than the first fulcrum. The blade body can also include a third fulcrum defined by a second aperture different from the one or more axially-elongated apertures. The third fulcrum may be spaced closer to the cutting than the first and second fulcrums. A lever, such as a screw driver, can be inserted into the apertures and placed against each of the fulcrums to lever slugs out of the interior of the blade body. The third fulcrum may alternatively be defined by another axially-elongated aperture that is located a different distance from the cutting edge than the axially-elongated aperture containing the first and second fulcrums.

A method of machining a workpiece is provided that is capable of forming a fresh air inlet in an arbitrary position in an outer shell of a container. According to the present invention, a method of machining a workpiece is provided that includes: machining to form a round hole in a workpiece using a boring drill having a tubular end portion, the end portion provided with a flat surface and a notch, and having a blade on a side of the notch, by pressing the flat surface against the workpiece while rotating the drill to contact the blade with the workpiece.

A method of machining a workpiece is provided that is capable of forming a fresh air inlet in an arbitrary position in an outer shell of a container. According to the present invention, a method of machining a workpiece is provided that includes: machining to form a round hole in a workpiece using a boring drill having a tubular end portion, the end portion provided with a flat surface and a notch, and having a blade on a side of the notch, by pressing the flat surface against the workpiece while rotating the drill to contact the blade with the workpiece.

A center locator is operated with a hole center for enlarging a round opening and includes a center seat having a through hole centrally defined therein, wherein the through hole is adapted to allow a centering drill of the hole cutter extending through the center seat. At least one adjusting device is longitudinally mounted to the center seat and formed with an engaging portion, wherein the at least one adjusting device is expandable relative to the center seat for adjusting a distance between the engaging portion of the at least one adjusting device and a center of the center seat.

A center locator is operated with a hole center for enlarging a round opening and includes a center seat having a through hole centrally defined therein, wherein the through hole is adapted to allow a centering drill of the hole cutter extending through the center seat. At least one adjusting device is longitudinally mounted to the center seat and formed with an engaging portion, wherein the at least one adjusting device is expandable relative to the center seat for adjusting a distance between the engaging portion of the at least one adjusting device and a center of the center seat.

A tool, such as a hole saw, including an open end cap geometry is provided. The end cap includes spokes extending between a hub and a rim. A plurality of openings are defined between the spokes, hub and rim. The area of the openings is substantially large relative to the area of the end cap such that the end cap is relatively lightweight and provides access into the hole saw for debris removal. The spokes are shaped and positioned to provide strength to the end cap.