Abstract: A multiple spindle bar machine is disclosed including a cylindrical spindle carrier assembly supporting a spaced apart array of spindle bearings. Workpiece holding spindles are rotatably journaled in the spindle bearings. A hollow spindle drive shaft extends through a central opening in the spindle carrier and includes a drive gear pinned to an end of the shaft. The drive gear intermeshes with spindle gears to drive the spindles at a uniform rotational speed. The spindle carrier assembly is rotatably supported by at least one set of tapered roller bearings bearing against an outer peripheral surface of a spindle carrier. The set of roller bearings are disposed in a notched annulus in an inner peripheral surface a headstock upright. Each roller bearing forms an acute included angle between the spindle carrier outer peripheral surface and a surface of the tapered bearing facing the spindle carrier. The set of tapered roller bearing is mechanically preloaded before machining operations commence.