The self-locking precision nuts assure their position by means of two or four locking elements. These elements are grafts of softer material than steel, that are mechanized during the same operation as that of the interior thread of the nut and are then fitted into the thread of the axle. Nevertheless, this does not modify the perpendicularity of the lateral face of the nut in relation to the axle of the nut. The grafts are fixed to head screws with an inside hexagon, centered on these elements.