The invention provides a machine tool comprising a base member, a workpiece support means mounted on the base member, a toolhead support means mounted on the base member, a toolhead assembly mounted on the toolhead support means, rotatable about a given axis relative to the toolhead support means, at least two tools mounted on the toolhead assembly, having axes radially disposed and circumferentially spaced relative to the given axis, a means for operating a selected one of the tools when the selected tool is disposed in a predetermined position relative to the workpiece support means operatively interconnecting the toolhead support means and the toolhead assembly for selectively, rotatably indexing the toolhead assembly about the given axis to position a selected one of the tools in the predetermined position; and means for locking the toolhead assembly relative to the toolhead support means when a selected one of the tools is disposed in the predetermined position.