An integral bladed rotor for a gas turbine engine is fixtured on an incrementally indexed arbor and enclosed by a shroud except for a portion of the rotor to be inserted into an electrolyte chamber for machining by opposed cathodes at a workpart machining position. The shroud and electrolyte chamber are in sealed relation when the portion of rotor is inserted for machining, and the shroud and electrolyte chamber include cooperative locating features to precisely position the rotor portion at the workpart machining position in the chamber. The shroud remains on the arbor during incremental indexing of the latter and is itself retained against substantial indexing movement while the rotor is indexed.