Alignment of machine components within casings

A method and device are provided to accurately align a machine component of generally circular cross-section within a surrounding machine casing that includes bottom and top halves of the casing. The bottom half and top half, in use, are bolted together at a split line occupying a horizontal plane. The component and the bottom half of the casing include complementary interdigitating members at three circumferentially spaced-apart locations, which include first and second locations at the split line on respective first and second horizontally opposed sides of the component, and a third location at bottom dead center. After lowering the component into the bottom half to engage the interdigitating members at the three locations, jacking apparatus is operated independently at each location to incrementally reposition the component within the bottom half. Shims are then inserted between the interdigitating members at the three locations to maintain the jacked position of the component.