Abstract: A spin index fixture has a housing which is provided with an air inlet shaft for permitting pressurized air to enter the housing and to propagate through grooves disposed along the outer surface of the sleeve. The air then enters into a clearance volume between the housing and the spindle and serves as an air bearing. The spindle is further provided with impelling recesses disposed circumferentially along the outside surface of the spindle at an axial location that is in alignment with the pressurized air inlets. The force of the air against the recesses rotates the spindle about its axis when the pressurized air supply contacts the recesses.