An inner shell for a rotating machine including at least one segment; and at least one complementary segment in operable communication with the at least one segment, the segments forming a support structure for a shroud ring; wherein the at least one segment and the at least one complementary segment are individually moved to change a set of dimensions defined by the at least one segment and the at least one complementary segment. A method for controlling a dimension of the shroud ring in a rotating machine is also disclosed.