While the roll being machined is in a rotary feed movement, and its groove arcuate central portion is machined by a tool rotated around a fixed geometrical center of the arc defining the central portion and subsequently receiving a radial feed, the bevel flanks conjugate with the profile central portion are machined alternatively by a shank cutter which is rotated in the groove radial section plane and simultaneously moved in the radial direction until the bevel flank being machined conjugates with the arc of the groove central portion. For this purpose, a slide housing the revolving table operatively associated with the roll drive and carrying guideways with a cutter head and a cutter mounted therein is arranged on the bed at its one side with respect to the means the for accommodation of the roll being machined, and a post having vertical guideways with a means for clamping the tool holder mounted therein is arranged at the other opposite side of the bed.