Abstract: An apparatus for working a elongated angle-iron workpiece having a pair of nonparallel flanges at least one of which is to be drilled has a transport unit for displacing the workpiece longitudinally through a working station and a support in the station for holding the workpiece with the one flange forming an acute angle with the horizontal. A drilling unit including a drilling tool can move horizontally in the station transverse to the workpiece and transverse to the workpiece and at the acute angle to the horizontal perpendicularly through the one flange. To obtain a given displacement along the workpiece flange, the carriage supporting the drill unit is moved horizontally through a horizontal distance equal to the desired displacement times the secant of the angle that the flange forms with the horizontal.