Abstract: The invention relates to an apparatus for the automatic mechanical centering and simultaneous clamping of elongate round bodies of various diameter. It consists of two collet chunks arranged at an axial distance from each other in the plane of symmetry of which lies the centering axis. The two chunk arms of each collet chunk include collet jaws each of which is provided with one slide element and one grip element. The effective flanks of the grip elements are concavely curved such that they in each case engage the circumference of the round bodies when the round bodies, sliding along the effective flanks on the slide elements, have been raised by the latter until their longitudinal axes coincide with the centering axis.

Abstract: For milling root butts on round timber, a trunk is clamped at a predetermined location and non-rotatable, a milling shaft with a milling tool is brought into abutment against the trunk, the milling tool mills in the trunk butt in the abutment region to a predetermined radial depth, then by a rotary device it is moved around the trunk and mills the root butt over the entire trunk periphery with controlling of the respective radial depth of the milling shaft by a sensor arranged to sense the outer surface of the trunk.

Abstract: A scratcher element in a cutter arrangement of a wood-cutting tool is formed of a rectangular plate and two projections outwardly extended from the side faces of the plate. The scratcher element is inserted in a special slot formed in a supporting strip of the cutter arrangement. These two projections each have a cross-section of the shape of a segment of the circular disc.