invention includes a frame whose basic component is the frame plate 10 which constitutes the base for the spindle support cabinet 12 and the chain support structure 14 spindle housings 16 and 18 are mounted upon the spindle support 12 and these housings rotatably support spindles 20 and 22 respectively the spindle 20 supports the workpiece chuck 24 while the workpiece chuck 26 is mounted upon the spindle 22 the spindle 20 is rotated by the controlled drive unit 28 fig2 drivingly connected to spindle 20 by the power transmission component 30 the workpiece 32 is affixed between the chucks 24 and 26 for rotation by the controlled drive unit 28 the workpiece 32 defines the axis of rotation of the apparatus in the drawings the workpiece 32 constitutes a crankshaft for internal combustion engines having main bearings 34 which are concentric to the axis of rotation it will be understood that the particular configuration of the workpiece 32 constitutes no part of the invention as any workpiece to be shaped by turning may be supported upon the chucks 24 and 26 behind the spindle support 12 a pair of spaced parallel vertically extending sprocket supporting plates 36 are affixed to and arise from the frame base 10 the sprocket plates 36 constitute the support for the three chain sprockets each sprocket actually constituting a pair of axially aligned sprockets rotatably mounted upon an axle the upper sprocket is designated at 38 the lower sprocket 40 is located directly below sprocket 38 and the.