Abstract: A shaft carries helically wound support surfaces for retaining cutter segments, such as diamond cutters, in a helical path. Oppositely wound helices extend continuously from the center to a limit position on each side of the cutter head. Each of the support surfaces is disposed in a direction substantially perpendicular to an extended surface to be cut or planed so as to provide a cut in the extended surface with a minimal force and without any side skipping of the cutter segments. Double wound helices provide a backup segment in the same plane and a natural balancing effect. Each of the helices in each double wound helix is uniformly spaced from the other double wound helix and is terminated at the same position at the center and at the limit position as the other helix but may be angularly displaced from the other helix by an angle of 90.degree. at the center and 180.degree. at the limit position. The cutter segments may be disposed on the helices in a balanced relationship.