Machining differential housings

A method of machining a hollow metal workpiece having a plurality of throughgoing holes and at least one port, the method comprising the steps of:

• picking up from a transfer station by a grab the hollow workpiece and displacing the workpiece out of the transfer station;
• thereafter, while holding the workpiece out of the transfer station with the grab,
• a) engaging a tool from outside with a first exterior surface of the workpiece and thereby finishing the first exterior surface;
• b) reorienting the workpiece by the grab and engaging a second tool with a second exterior surface of the workpiece offset from the first exterior surface and thereby finishing the second exterior surface;
• c) fitting a third tool through the port of the workpiece and positioning the third tool inside the workpiece adjacent one of the holes;
• and
• d) coupling a drive spindle through the one hole of the workpiece with the third tool and machining an inner surface of the workpiece adjacent the one hole with the third tool;
• and
• displacing the workpiece back into the transfer station and releasing it from the grab.