Abstract: The bar is machined, according to a required longitudinal and/or circumferential profile, by rotating tools carried by a main plate driven in rotation on the frame, the tools being connected to the plate by tool supports radially mobile on this plate, and depending on the required profile, a radial movement of the tool supports is controlled according to the axial position of the bar in relation to the chassis and/or the circumferential positions of the tools in relation to the bar. To control the radial movement, a secondary plate is driven in rotation coaxially to the main plate. The secondary plate including a device for actuating tool supports, arranged so that the positions of the tool supports depend on the relative angular position between the main plate and the secondary plate and, to permanently adjust the radial positioning of the tools during the rotation of the main plate, the relative angular position is modified.