A method to control a power tool, especially a core drill, including a motor as the drive for the power tool, a control unit, a power display, a transmission having at least a first gear and a second gear, a first sensor to detect the rotational speed of at least one component of the transmission and a second sensor to detect the rotational speed of the motor. The method includes the following steps: ascertaining a first rotational speed of the at least one component of the transmission when the transmission has been put into a gear, ascertaining a first rotational speed of the motor when the transmission has been put into a gear, ascertaining the selection of the gear on the basis of a first prescribed ratio of the first rotational speed of the at least one component of the transmission and of the first rotational speed of the motor on the basis of a look-up table, and setting the limit value of the power display on the basis of the look-up table as a function of the gear that has been selected. A power tool for purposes of using the method.

There is provided a cutting accessory for a power tool comprising a body bearing a cutting surface, wherein the body comprises a plurality of spaced apart regions of reduced thickness within the cutting surface to create at least one interrupted cutting surface overlying a second cutting surface. Abrasive cutting material is affixed to the cutting surface. The regions of reduced thickness are equispaced along the cutting surface. The body can be substantially tubular or a linear edge blade.

A core drill bit 1 includes a tubular shaft 12, a mounting platform 34 provided on a proximal end of the tubular shaft 12 for mounting the core drill bit on a power tool 35, and an annular cutting section 2 provided with abrasive cutting segments 3 arranged at a distal end of the tubular shaft 12. The core drill bit 1 further includes a transponder 24 and a slit 27 in the tubular shaft 12. The slit 27 forms a slit antenna 26 for the transponder 24.

The present invention is an attachment that reversibly connects to a skid steer, front loader, or other heavy equipment. The attachment allows a user to quickly and efficiently core holes in concrete and asphalt. The attachment comprises a frame assembly that rests upon the surface of concrete being cored and a carriage assembly. The carriage assembly connects a drum saw to the frame assembly. The carriage assembly moves vertically up and down along the length of the frame assembly while coring a hole in concrete. The attachment includes two, three, and four-post embodiments. The three and four-post embodiments provide include a larger frame assembly that provides additional stability to the attachment while allowing the user to quickly reposition the attachment to core additional holes.

A drill bit has a cutting portion having an annular portion, where the annular portion has a first end on which is disposed a cutting element and a second end that includes an outer insertion element and a stop shoulder. The drill bit has a drill shaft portion having a cylindrical drill shaft, where the drill shaft has an inner insertion element with an end face on a side of the drill shaft facing the cutting portion. The outer insertion element and the inner insertion element together form a plug connection in an insertion direction that is parallel to the axis of rotation and the insertion elements are connectable to each other via a pin element that is movable into a slot-shaped recess. The pin element is attached to an outside of the inner insertion element and the outer insertion element has the slot-shaped recess.

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.

Methods and devices for the execution of core drillings in a material by a drilling unit, which makes use of a drill bit, and such drill bits that are made up of a hollow cylindrical core barrel, which has an end plate at its rear end and abrasion elements, which serve the abrasion of material, at the front end as well as at least two high-pressure jet nozzles, which can be connected with a high-pressure source of a blasting medium. The high-pressure jet nozzles are arranged on the inner surface of the core barrel and/or its end plate and are oriented into the inside of the core barrel. As a result of a combined forward motion and rotation of the drill bit, a drilling core is formed from which an abrasion takes place by means of the blasting medium, whereby overburden is removed from the drill bit.

A drill bit is disclosed. The drill bit has a cutting portion having an annular portion, where the annular portion has a first end on which is disposed a cutting element and a second end that includes an outer insertion element and a stop shoulder. The drill bit has a drill shaft portion having a cylindrical drill shaft, where the drill shaft has an inner insertion element with an end face on a side of the drill shaft facing the cutting portion. The outer insertion element and the inner insertion element together form a plug connection in an insertion direction that is parallel to the axis of rotation and the insertion elements are connectable to each other via a pin element that is movable into a slot-shaped recess. The pin element is attached to an outside of the inner insertion element and the outer insertion element has the slot-shaped recess.

A drill bit, which is rotatable in a direction of rotation about an axis of rotation, is disclosed. The drill bit has a cutting portion with an annular portion where the annular portion has a first end on which is a cutting element and has at a second end a first insertion element. The drill bit has a drill shaft portion with a cylindrical drill shaft which has at an end, towards the cutting portion, a second insertion element. In a direction of insertion parallel to the axis of rotation, the insertion elements form a plug-in connection and can be additionally connected by way of at least one pin element which is movable in at least one slit-shaped clearance.

The present invention seeks to provide a simple, easily realisable and inexpensive solution to the problems discussed above. The present invention further seeks to provide a hole-saw device which enables rapid changes of hole saw. The present invention also seeks to provide a simple device for enlarging apertures which is simple, cost effective and can be used with standard drills of corded and battery types as well as manual types.