Abstract: During passage of an I-beam through a punching press for punching holes vertically through its web, holes are also punched through its flanges by horizontally acting punches of the present invention. Four C-shaped punching heads are provided for the flanges. To permit punching closely adjacent holes, two punches are powered by a single hydraulic cylinder, unless one is deactivated. A joint gauge screw precisely adjusts gauge (the spacing between the two punches), and may be raised or lowered for centering as to web. Before each flange punching operation, the web is pressed firmly against a fixed block level with the web die. The piston of the hydraulic cylinder is of such large diameter that the varying positions of the punches will lie within the projected periphery of the piston rod.