Abstract: A method of manufacturing hemispherical tank heads is disclosed in which a pair of planar lune members having a generally football shape are cut from flat metal stock. The members are each then formed into a three dimensional lune section having a generally orange-peel sectional shape. Each section is placed onto a trim jig and a first edge of the sections are trimmed to leave some excess material beyond a desired trim line. A second edge of each section is then trimmed to a desired trim line. The two trimmed sections are placed on a joining jig with the second edges of the sections juxtaposed and joined to form a hemispherical member. Finally, the hemispherical member is placed onto the trim jig and the excess materials on the first edges is trimmed to form an accurate hemispherical tank head. Preferably, the trim jig is rotated relative to a stationary plasma torch during all trimming operations.