A collet bush includes a tapered cylindrical outer surface, a cylindrical inner surface and a flow path. The collet bush is to be inserted into a concentric collet that is attached to a handheld tool driving device in order to position the tool driving device to a workpiece. The tool driving device holds, rotates and feeds a tool. The tool driving device has a function to suck chips. The outer surface is for expanding the concentric collet. The inner surface forms a through hole for slidably fitting the tool. The flow path is for taking in air used for sucking the chips inside the collet bush. The tool driving device includes the above-mentioned collet bush and the concentric collet.

An insert holder has a holder longitudinal axis defining opposite forward to rearward directions, a holder end surface located at a forward end thereof, and a holder peripheral surface extending circumferentially about the holder longitudinal axis. The insert holder has upper and lower jaws which are spaced apart by a clamping recess recessed in the holder end surface. The upper jaw is resiliently movable with respect to the lower jaw upon rotation around an angled pivot axis. The insert holder includes a forwardly located insert mounting portion which includes a forwardly protruding clamping finger and a forwardly protruding support rib. The clamping recess is defined partially by an elongated recess hinge surface formed on an angled hinge portion. The recess hinge surface includes a first hinge end and a second hinge end, longitudinally spaced apart from one another. The second hinge end is located forward of the first hinge end.

An insert holder has a holder longitudinal axis defining opposite forward to rearward directions, a holder end surface located at a forward end thereof, and a holder peripheral surface extending circumferentially about the holder longitudinal axis. The insert holder has upper and lower jaws which are spaced apart by a clamping recess recessed in the holder end surface. The upper jaw is resiliently movable with respect to the lower jaw upon rotation around an angled pivot axis. The insert holder includes a forwardly located insert mounting portion which includes a forwardly protruding clamping finger and a forwardly protruding support rib. The clamping recess is defined partially by an elongated recess hinge surface formed on an angled hinge portion. The recess hinge surface includes a first hinge end and a second hinge end, longitudinally spaced apart from one another. The second hinge end is located forward of the first hinge end.

A drill bit for creating a borehole includes a drill shaft portion which has a tubular drill shaft, a receiving portion which has a cover and an insertion end, and a connecting device which connects the drill shaft portion and the receiving portion together releasably or non-releasably. The tubular drill shaft is configured as a welded spiral tube.

Tool system 1 comprising a tool holder 2 that has an insert seat 17 for receiving a cutting insert 6, and comprising a clamping element 4 that has an opening 26 for receiving a clamping means 15, an interface 30 being arranged between the tool holder 2 and the clamping element 4, and channels for the purpose of cooling by means of a fluid being arranged in the tool holder 2 and the clamping element 4, and a sealing means 31 being arranged in the region of the interface 30.

Entry sheet for drilling including a metallic foil and a layer of a resin composition, the layer formed on the metallic foil without interposing an adhesion layer, in which the layer of the resin composition has a peak attributable to a carbon atom-oxygen atom double bond appearing at 1700 to 1750 cm.sup.1 and a peak attributable to a carbon atom-oxygen atom single bond appearing at 1080 to 1300 cm.sup.1 in infrared spectroscopy, and when the absorbance at the peak attributable to the carbon atom-oxygen atom double bond appearing at 1700 to 1750 cm.sup.1 is represented by Abs(CO)L, and the absorbance at the peak of the carbon atom-oxygen atom single bond appearing at 1080 to 1300 cm.sup.1 is represented by Abs(CO)L, the layer of the resin composition has an absorbance ratio (C) of 0.12 to 1.80, the absorbance ratio (C) represented by the following expression (1).
Absorbance ratio(C)=Abs(CO)L/Abs(CO)L Expression (1).

An entry sheet for drilling comprising: a metallic foil; and a layer of a resin composition, the layer formed on the metallic foil without interposing an adhesion layer, wherein the surface of the layer of the resin composition, the surface being in contact with the metallic foil, has a dispersion term SD of surface free energy in a range from 27.0 to 37.0 mJ/m.sup.2 and a polar term SP of the surface free energy in a range from 0 to 5.0 mJ/m.sup.2.

A collet includes an axially rearward end and an axially forward end; a nose portion; a body portion having an outer surface and an inner surface for engaging a shank of a tool; a plurality of slots extending from the inner surface to the outer surface; and a plurality of coolant channels disposed within the collet between the plurality of longitudinally extending slots and extending entirely from the axially rearward end to the axially forward end of the collet. Slots include a first slot extending from the axial forward end to within an intermediary zone, a second slot extending from the axial rearward end to at least the tool holder engagement zone such that the second slot does not intersect the first slot, and a third slot from within the tool engagement zone to within the intermediary zone such that the third slot circumferentially overlaps the first and second slots.

A drill has a thinning rake face formed in the front end. An intersection ridgeline between the thinning rake face and the tip flank face is the thinning edge. On the opposite side of the rotation direction, the first and second thinning wall surfaces (6b, 6c) and are formed. Viewed from the front, an intersection angle between the thinning edge (4a) and the first thinning ridgeline is larger than 95. The second thinning ridgeline (L2) is bent to the opposite side of the rotation direction. The thinning edge and the first thinning ridgeline are connected via a concave curve line. The first and second thinning wall surfaces are connected via a concave surface, and a curvature radius of the concave curve line is smaller than a curvature radius of the concave surface.

A cutting tool, in particular for machining metal, is described. It comprises a tool main body that has at least one interface for receiving a cutting insert that can be attached to the tool main body. At least one cooling duct is provided in the tool main body and has, at its end on the interface side, an outlet section with an elongate outlet cross-section on the interface side. The tool main body is manufactured at least in sections by means of a generative manufacturing process. A method for manufacturing such a cutting tool is also presented.