Abstract: A reference straight-edge is mounted on the worktable of a machine tool so that the position of the worktable and a workpiece carried thereon can be determined in respect of the x-axis of the machine tool by sensing the straight-edge; in addition a linear scale is carried by the tool carriage of the machine tool for cooperation with a reading head to provide an indication of the tool position along the x-axis. Another linear scale is carried by the worktable and coacts with a read head to provide the position of the worktable and workpiece along the z-axis. The linear scale of the tool and the reference straight-edge, and the reading head and sensing device associated therewith are all in the same plane. The workhead and tailstock spindles are equipped with hydrostatic bearings which have sensing devices to determine forces applied to workpieces carried between the headstock and tailstock on a worksteady and cooperate therewith to activate a probe to offset such forces.