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 the 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 the 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 saw includes a cylindrical body having a sidewall with a first end and a second end opposite the first end. The cylindrical body includes a gullet formed in the sidewall between a leading surface, a trailing surface, and a bottom surface of the sidewall. The gullet defines a central longitudinal axis extending between the first and second ends of the sidewall that is obliquely oriented relative to a rotational axis of the hole saw such that the gullet is angled from the first end to the bottom surface in a direction toward a cutting direction of the hole saw. The gullet has a dimension measured parallel to the rotational axis between the first end of the sidewall and the bottom surface of the gullet that is greater than 1.5 inches. The hole saw includes a cutting tooth coupled to the first end of the sidewall adjacent the gullet.

A coring unit comprises a clamping arrangement for releasably attaching the coring unit to a structure into which a core is to be cut. A bit is provided comprising an elongated tubular body having a cutting surface at a first circular end of the elongated tubular body for cutting the core. The unit includes a drive system adapted to rotate and linearly translate the bit so that the drive system rotates the bit and moves the bit with respect to the clamping arrangement to advance and retreat the bit through the structure to cut the core from the structure. A method of using the coring unit is also described. The unit and method permit an accurate, reliable, safe, and reproducible cutting of a hole in a structure. The unit and method find particular application in cutting holes in studs of wood frame structures to accommodate services such as wires and piping.

A coring unit comprises a clamping arrangement for releasably attaching the coring unit to a structure into which a core is to be cut. A bit is provided comprising an elongated tubular body having a cutting surface at a first circular end of the elongated tubular body for cutting the core. The unit includes a drive system adapted to rotate and linearly translate the bit so that the drive system rotates the bit and moves the bit with respect to the clamping arrangement to advance and retreat the bit through the structure to cut the core from the structure. A method of using the coring unit is also described. The unit and method permit an accurate, reliable, safe, and reproducible cutting of a hole in a structure. The unit and method find particular application in cutting holes in studs of wood frame structures to accommodate services such as wires and piping.

A method for determining a recommendation of a gear to be engaged for a core drill. In the method, it is possible to use for example a drop in a rotational speed of a core bit of the core drill in the event of sudden deactivation of the motor of the core drill in order to determine the diameter of the core bit. Alternatively, the diameter of the core bit can be determined when the drill is started up or turned on. The diameter of the core bit is then used as the basis for the recommendation of the gear to be engaged. In a second aspect, the invention relates to a core drill with which the method can be carried out.

A drill includes drill body and peripheral insert having a radial cutting edge extending generally in a direction of a radius of the drill body, and a central insert. The peripheral insert includes a rake face including a plurality of chipbreaker protrusions. A first angle measured between a line tangent to forward ends of the plurality of chipbreaker protrusions and the central axis of the drill body extending toward the shank end is an acute angle. Also a peripheral insert is disclosed.

A method for producing a drill ring for a core drill bit is disclosed. The method includes constructing at least two green parts from encapsulated diamond particles, the diamond particles being covered by a powder mixture. The green parts are formed into ring segments under the effect of pressure and the ring segments are annularly assembled and sintered under temperature action to form a continuous drill ring.

The present disclosure describes and teaches a drill safety system including a magnetic unit, a vacuum unit, and an improved hole saw drill set. The various parts of the drill safety system may be used individually or in combination with one another. The user may use the magnetic unit to surround the drilling site so that metal drill shavings on the drill surface may be collected by the magnetic unit. In addition, the magnetic unit includes a flippable top mechanism, allowing convenient disposal of the debris. The vacuum unit is fitted to the inner surface of the drilling site, collecting debris that fall through. The improved hole saw prevents over-penetrating by the drill, reducing the likelihood of damaging equipments underneath the drill site. This makes the drill particularly suitable for drilling holes during electrical work.

There is provided a drill bit for cutting tiles comprising a hollow body portion bearing an annular cutting surface at one end and a wax plug located within the hollow body portion, wherein an internal wall of the hollow body portion has at least one region of reduced thickness so as to provide one or more channels along which melted wax can flow to reach cutting surface. The channels can be provided by an offset central passage within body portion, or as elongate grooves around the internal wall of the hollow body portion. The channels can be helical grooves.