Cubic cutting insert for boring or plunging

Rotatable tool for preparing rotational symmetrical surfaces and having a shaft which is mountable for rotation about an axis thereof, and a cutting head comprising at least one recess for receiving a cutting insert, a base surface of said recess being provided for supporting a bottom or top surface of a cutting insert and being tilted by an angle between 5° and 90° with respect to said axis,

• wherein the cutting insert comprises a cuboid body having a substantially square top face and a bottom face, said top face and bottom face being connected by means of four peripheral adjoining side surfaces,
• wherein at least two cutting edges are formed at the transition of the top face to at least two side surfaces, that cutting edges defining a plane of the top face,
• wherein the plane defined by the top face cutting edges has maximum dimensions of 6 mm×6 mm, the bottom face having a supporting surface which is formed exactly parallel to the plane defined by the top face cutting edges by means of grinding within a tolerance of less than 5 angular minutes, the top face and the bottom face each being formed as continuous planar surfaces,
• wherein the cutting edges of the top face and the bottom face are defining the shape of a cube within an edge length tolerance of 5%, and
• wherein said base surface of said recess, which is provided for the support of a respective non-active face of said top and bottom faces, respectively, is ground to a particular angle between 5° and 90° relative to said axis within a tolerance of less than 5 angular minutes.