An adapter for holding a workpiece to be machined in an accurately located axial position can include a main sleeve having an interior wall defining a passage extending therethrough with at least one inner surface angled inwardly toward a centerline of the passage, a workpiece locator engageable within the passage and supporting a positive axial location stop, an axially and radially moveable collet interposed between the main sleeve and a workpiece to be processed, and a rotatable sleeve engageable with the collet for accurately locating the workpiece to be processed by radially grasping the workpiece to be processed and axially moving the workpiece into engagement with the positive axial location stop.