A method and apparatus for aligning structures. In one advantageous embodiment, an apparatus comprises a tapered member and a plurality of segments. The tapered member has a first end and a second end, a diameter that increases from the first end to the second end, and the diameter has a first center. The each of the plurality of segments has an inner surface and an outer surface, wherein the plurality of segments define a tapered channel capable of receiving the tapered member, wherein the outer surface has an outer diameter with a second center corresponding to the first center, and wherein movement of the plurality of segments to the second end increases the outer diameter with the second center remaining in around a same location.