Abstract: A workpiece support for supporting multiple workpieces in an immersion bath for spark machining including a stationary workpiece support and an adjustable workpiece support in side by side relation, an electrode holder overlying the supports and carrying a pair of electrodes thereon, the adjustable workpiece support having a pair of cylindrical rollers rotatable on axes eccentric of the cylindrical outer face, a coverplate with openings receiving the outer surfaces of the rollers therethrough, a closed chamber containing gear wheels connected to the rollers for simultaneously turning the eccentric rollers about their rotation axes, and a manual operating apparatus for turning the gear wheel.