Abstract: The application seeks to eliminate errors introduced by bearings and supports. It does so by integrating the drive means, in the form of a piezoelectric actuator, into the bearing or support. Thus the bearing no longer acts against the drive means, eliminating errors. It also describes a drive mechanism for elongate prismatic objects (140). The mechanism uses piezoelectric drives (148) and achieves very high accuracy of positioning with minimal backlash etc, whilst occupying only a small volume. This makes it suitable for use in electro-discharge machining and electro-discharge texturing operations where one or more wire electrodes (140) need to be positioned accurately with respect to a workpiece and maintained in that relative position as the workpiece erodes and the electrode (140) is consumed.