A support movable in a predetermined direction carries a cutting insert having a body formed with a front face lying generally in a plane generally parallel to the direction and an arcuate edge face having an inner end merging with the front face, an outer end and defining between the inner and outer ends an arcuate cutting edge. A side face directed forward in the direction defines an outer cutting edge extending transversely of the front face from the outer end of the arcuate cutting edge.