Abstract: A cutter element having a peripheral working surface and a frontal face, defining therebetween a cutting edge. The working surface of a cutter element is formed in the shape of a solid of rotation generated about a longitudinal axis. The axial section of the working surface forms with a plane passing through its cutting edge and perpendicular to the longitudinal axis, an angle selectable within 40.degree. to 120.degree.. The cutter element is provided with a shaft, which is supported for rotation around the longitudinal axis in a holder adapted to be mounted on a heading or combine tool.