A tool for creating a wall opening. The tool includes a hole saw; and a centering jig having a center axis, where the centering jig is constructed as a centering ring, into which the hole saw can be pushed at least partly, and in that both the hole saw and the centering ring have on their circumference an opening such that this can be pushed transverse to the center axis completely onto a line.

The present invention is an accessory device that hole coring machine, wherein the hole coring machine is utilized to quickly and efficiently core holes in concrete and asphalt. The accessory device comprises a stabilizer assembly that is coupled to a base of the hole coring machine. The stabilizer assembly includes at least one stabilizing frame that is formed to the outside diameter of a drill saw bit of the hole coring machine. The at least one stabilizing frame is coupled to an air compressor that causes the stabilizing frame to move relative to the drill saw bit during operation of the hole coring machine. The at least one stabilizing frame aids in maintaining the shape of the drill saw bit and reduces vibration and binding of the drill saw bit while forming a hole in concrete and/or asphalt.

A method for operating a power tool is provided. The power tool has a tool, in particular a drill bit, and a motor, while the motor is a brushless electric motor. In the power tool there is implemented a rotational speed graduation of an electronic form, with which a circumferential speed at the tool of the power tool can be kept essentially constant, while a rotational speed spread DELTA_n of greater than 2 is achieved by the design, dimensioning and/or control of the motor. Also provided is a tool device, for example a core drilling device, with which the proposed method can be carried out. An essential advantage of the invention is that the rotational speed spread DELTA_n of greater than 2 is achieved without a mechanical transmission on the power tool. Instead, a rotational speed graduation of an electronic form is used in the present invention.

A method for releasing a drill core from a drill bit of a core drilling device, with an intuitive movement being recognized and used as a trigger for a shaking process for the drill core. The intuitive movement may be for example a shaking movement of the core drilling device. A core drilling device for carrying out the proposed method is also provided. The core drilling device preferably includes a sensor system for detecting the intuitive movement of the core drilling device, while the sensor system may for example comprise a gyro sensor.

Provided is a core drill having one touch lock function of a core bit, and particularly, new-conceptional technology of maintaining locking automatically during assembling a core bit and a decelerating unit, and releasing the locking easily, and the core drill conventionally disclosed had problems that movement and separation of the core bit and the decelerating unit of the core drill often occur during operation, because there is no specific lock function in the state that the core bit and the decelerating unit are assembled, and in this disclosure of the present invention to solve the problems, there is provided new technology for automatically maintaining locking if releasing the locking after inserting a decelerating connector coupled to a core bit into a connection hole formed in a spindle in the state of releasing the locking by pressing the lock pin elastically installed in a lock housing fittingly installed outside the spindle.

A core drill bit can include a first region and a second region. The first region can include abrasive particles in a first bond matrix, and the second region can include abrasive particles in a second bond matrix. The first region is connected to the second region. The first region comprises at least one different abrasive characteristic than the second region. At least one of the first and second region can include a Fast Fourier Transform value greater than 1.

A support assembly for a core drill which utilizes an improved high strength spoked reinforcer. The reinforcer may be removably mounted a core drill tube by fasteners. A drive connection is removably mounted and centrally located on an outer disc of a pair of discs. The drive connection is adapted to connect with a drive shaft to cause rotation of the tube. The assembly can also include a split in the disc when the high strength spoked reinforcer is not welded thereto, thereby providing a means of water control. The high strength spoked reinforcer can be a separate piece that is bolted to the disc or can be integrally formed as one piece therewith.

A method to control a power tool (1), especially a handheld core drilling machine, includes a drive (10) to drive a tool (30) and a control unit (40) for when a workpiece (W) is being processed. The method encompasses the following method steps: setting the rotational speed of the drive at a first value; measuring a first power consumption value for the drive; setting a threshold value for the power consumption of the drive; and increasing the rotational speed of the drive to a second value if the power consumption of the drive (10) exceeds the threshold value due to an increase in the drive load. The power tool includes a drive (10) to drive a tool (3) and a control unit (40) to control at least the rotational speed of the drive.

A hole saw blade comprises a substantially cylindrical body with a pair of sides extending substantially concentric to each other. The sides have an inner surface and an outer surface. A cutting edge extends from an end of the body. A plurality of teeth defines the cutting edge. The teeth are arranged in an alternating pattern in which a first tooth extends inwardly of a cylinder containing the inner surface a first inner distance. A second tooth is adjacent to the first tooth extends outwardly of a cylinder containing the outer surface a second outer distance. A third tooth is located adjacent the second tooth on an opposite side of the first tooth and that extends inwardly of the cylinder containing the inner surface a third inner distance greater than the first inner distance.

The invention concerns a drill bit for percussion drilling or impact drilling use for cutting reinforcing steel in concrete, wherein the drill bit has a substantially hollow-cylindrical carrier body extending along a geometric drill bit axis, wherein the carrier body has at least one chisel tooth with a substantially radially extending first chisel edge. It is proposed that the first chisel edge is arranged in a middle portion of the chisel tooth, in particular precisely centrally, in the circumferential direction, and the chisel tooth has a second chisel edge extending substantially tangentially to the circumferential direction of the drill bit.