Abstract: In the formation of engagement grooves in the shank of a tool for use in a hammer drill or chipping hammer, a matrix or die is divided along a junction plane into two matrix halves. A bore for holding the tool to be punched is formed along the junction plane so that the plane divides the bore in half in its axial direction. Guide openings are formed in the opposite sides of the matrix extending into the bore for receiving punching dies. The matrix halves combine to form these guide openings which are located in the junction plane so that the punching pressure is applied in this plane. The closing pressure for holding the matrix halves together is applied at right angles to the junction plane.