Abstract: A rotary cutter is provided with a spiral plane bit which comprises a mounting plate extending spirally in the axial direction with a constant width, the mounting plate being made in such a manner that it is spirally cut out of a hollow cylinder with the inner radius of the mounting plate and a bit edge member extending also spirally along one lateral margin of the mounting plate and being fastened thereto, wherein there are provided a plurality of fastening holes arranged in the mounting plate in the longitudinal direction thereof, through which fastening elements extend radially into a plurality of threaded holes so as to fasten the mounting plate together with the said bit edge member on a rotary shank.

Abstract: A router bit is provided with an even number of paired cutting edges. Each pair of cutting edges has opposite helix hands at the same helix angle with respect to the axis of rotation and a portion where the pitch of the cutting edge is constant when the cutting edge is developed along the circumference of rotation in the longitudinal direction. Such router bit is suitable for chamfering and finishing the side of board containing fiber reinforced plastics.

Abstract: A rotary cutter and method of making same having a plurality of wear resistant material tipped helical cutting teeth therealong and comprising a plurality of cutter discs removably mounted in stacked relationship on a mandrel. Each disc comprises a circular member having a plurality of circumferentially spaced cutting teeth extending therearound and wherein each cutting tooth incorporates a hard, wear resistant insert having a helical rake facet and a helical relief facet defining the cutting edge which is in the form of a true geometrical helix. Coacting means are provided on the mandrel and each disc for rotationally positioning and aligning the discs such that the helical cutting edges thereon define in combination a substantially continuous geometrically true helical cutting edge extending the entire length of the cutter.

Abstract: To permit resharpening of cutter blades of a helical milling cutter, the cutter blades or bits of a multi-bit cutter have decreasing thickness, and are placed in grooves having the same helix radius, but the centers of the helical axes offset from the center of rotation of the cylindrical cutter body in the direction towards the associated groove, so that cutter blades of lesser thickness are still seated firmly in the bottom of the respective groove. Upon dulling of the cutters, the thinnest one of the cutter blades is discarded, the thickest one only replaced and the worn blades moved up one step along the circumference of the body into grooves which are progressively more shallow, to compensate for decrease in thickness of the respective cutter bits upon regrinding to resharpen the bits.

Abstract: A rotary cutting tool blank comprises a cutting portion having a longitudinal axis and a plurality of teeth extending the length of said cutting portion, with each of the teeth having a cutting face and a trailing face and a land surface bridging the cutting and trailing faces. The land surfaces are interrupted by a plurality of spaced transverse depressions of relatively large radius arcuate cross section to form a plurality of cutting edge portions at the junction of the cutting face and the uninterrupted portions of the land surface. The cutting edge portions have a positive rake angle, and the trailing and cutting faces of each tooth have surfaces which undulate generally sinusoidally from one end of the cutting portion to the other so that the rake angle of each cutting edge portion varies continuously along its length. The cutting tool blank can be transformed to a cutting tool ready for use simply by suitably relieving the land surfaces to form cutting edges at the aforementioned cutting edge portions.

Abstract: A milling cutter, especially contour milling cutter, which comprises individual cutting elements helically arranged around the axis of the cutter body and connected thereto. These cutting elements are separated from each other in circumferential direction of the cutter body by chip grooves. All of the chip grooves extend helically about the axis of the cutter body in the same sense. Webs project from the cutter body and extend in the same sense helically about the axis of the cutter body while being separated from each other by the above mentioned chip grooves. Along the outer web edges which are located on a common cylinder mantle there are provided depressions or cutouts separated from each other by web sections which form the individual cutting elements.