Abstract: A tool shaft is supported for rotation about a vertical axis by means of upper and lower bearings. A motor drives the shaft at least at 500 rpm. A gap is formed radially between the shaft and an adjacent stationary member, the gap extending from one bearing to the other. A reservoir which contains lubricating oil communicates with the gap to supply oil thereto to cool and lubricate. The tool shaft carries a helical thread disposed within the gap which pumps the oil upwardly through the gap and through the bearings to create a hydrostatic bearing for the shaft segment extending between the bearings. The tool shaft is driven by a gear shaft which also is provided with a hydrostatic support by means of oil pumped through a radial gap by means of helical threads which are stationary, but which are disposed closely adjacent a surface of the gear shaft.