Abstract: A method of forming an opening in a layered structure includes providing a layered structure including a first layer and a second layer and a near-zero gap interface defined between the first layer and the second layer; providing an opening through the layered structure such that the opening extends through the first layer and the second layer; and working simultaneously the opening in the fay surface of the first layer and the opening in the fay surface of the second layer without separating the first layer and the second layer. An internal chamfering device is also disclosed.

Abstract: A deburring tool for deburring the edges of boreholes. The tool has a base body in which at least one recess aligned across the longitudinal axis of the base body is provided, where at least one blade is arranged in said recess so it can be displaced under spring load in the longitudinal direction of the recess. A compression spring is provided in the longitudinal bore of the base body and comes in contact with one end of a control pin whose other end engages in a control recess in the blade to provide at least a holding power to the blade in the direction of displacement.

Abstract: A drill having at least one and generally at least two cutting inserts fixed in a cutting end of the drill and in which each cutting insert is a polygonal body having at least three cutting vertices and respective cutting edges between the vertices which are set back so that cutting points are formed close to a vertex. The partial cutting edges formed by the setback extend rectilinearly to the cutting points and include an angle of up to 170.degree. between them.

Abstract: A drill for stack drilling comprises a drill body, a central cutting insert, and a peripheral cutting insert. The inserts have active cutting edges arranged such that the drill successively cuts radially outwardly from the center of the drill in order to avoid the formation of break-out slugs. The active cutting edge of the central insert has three cutting edge portions forming obtuse angles with one another. The radially innermost one of those cutting edge portions is shorter than each of the other two cutting edge portions.

Abstract: A combination drilling and skiving tool including a longitudinally extending hollow skiving sleeve slidably and concentrically mounted on a right-handed twist drill. Dogs or pawls provided on the internal periphery of the skiving sleeve engage with the helical grooves of the drill. During a clockwise rotation of the tool, the drill moves downwardly and the sleeve translates upwardly, so that the drill performs a drilling operation on a workpiece. On the other hand, the drill moves upwardly and the sleeve translates downwardly, when the tool is rotated in a counter-clockwise direction, and the sleeve performs a skiving operation. The drilling and skiving operations are separate, independent and exclusive of each other.