The invention relates to an elongated feed beam (4) for use on a drill rig (1), which feed beam comprises a profiled beam of a light metal or a light metal alloy made from a hollow extruded profile with a substantially rectangular cross section. The profiled beam comprises an upper wall (11), a lower wall (12) and two side walls (13, 14) and at least one pair of external guide beads (8, 9). The individual guide beads (8, 9) of the at least one pair of guide beads are placed on either side of either the upper wall (11) or the lower wall (12) at the locations where said upper or lower wall (11, 12) meets the opposed side walls (13, 14). The guide beads (8, 9) have a substantially prismatic cross section.