Abstract: An apparatus for use in machining and statically balancing a large and heavy workpiece such as the runner of a hydraulic turbine. The apparatus includes a vertical center support column on the upper end of which is mounted a rotatable turntable. The workpiece which is to be machined and statically balanced is suitably clamped to and rotates with the turntable, the workpiece extending radially beyond the turntable so that as the turntable is rotated the workpiece is moved past a machining tool which is suitably supported along the path of rotary movement of the workpiece. The turntable is detachably secured to a composite member which comprises a bearing, such as a roller bearing, integral with a gear, such as an internal ring gear, the composite member being in underlying relation to the turntable.