A workstation for machining plates of stone, marble, plastic, synthetic material, or the like, comprising: - a bench, defining a main working surface that can be equipped with supports for receiving and blocking the plates to be machined in a raised position with respect to the main working surface; - two fixed sides arranged at the two sides of the working surface; - an overhead cross member guided on the two sides like an overhead travelling crane, in a horizontal direction Y orthogonal to the horizontal direction X of the cross member; - a carriage mobile in the aforesaid horizontal direction X on the cross member; - at least one operating head, carried by the aforesaid carriage and mobile with respect to the latter in a vertical direction Z, said operating head being equipped with means for coupling a rotary tool for carrying out finishing operations on the edge of a plate to be machined or for coupling a disk blade thereto for carrying out cutting operations on the plates to be machined; - motor means for governing the cross member, the carriage, and said at least one operating head respectively along the three axes Y, X, Z; - electronic means for controlling said motor means; and - an auxiliary working surface, of a sacrificial type to be used during the operations of cutting of the plate, which can be displaced in a guided way (15, 16, 17) in said direction Y, between a first position, in which overlies the main working surface, and a second position in which said sacrificial working surface is set horizontally spaced from the main working surface, said workstation being characterized in that the aforesaid auxiliary working surface is defined by a structure independent of the bench and of the main working surface and in that in the aforesaid first position the auxiliary working surface is in a position set vertically at a distance above the main working surface and is not supported by the latter. - a bench, defining a main working surface that can be equipped with supports for receiving and blocking the plates to be machined in a raised position with respect to the main working surface; - two fixed sides arranged at the two sides of the working surface; - an overhead cross member guided on the two sides like an overhead travelling crane, in a horizontal direction Y orthogonal to the horizontal direction X of the cross member; - a carriage mobile in the aforesaid horizontal direction X on the cross member; - at least one operating head, carried by the aforesaid carriage and mobile with respect to the latter in a vertical direction Z, said operating head being equipped with means for coupling a rotary tool for carrying out finishing operations on the edge of a plate to be machined or for coupling a disk blade thereto for carrying out cutting operations on the plates to be machined; - motor means for governing the cross member, the carriage, and said at least one operating head respectively along the three axes Y, X, Z; - electronic means for controlling said motor means; and - an auxiliary working surface, of a sacrificial type to be used during the operations of cutting of the plate, which can be displaced in a guided way (15, 16, 17) in said direction Y, between a first position, in which overlies the main working surface, and a second position in which said sacrificial working surface is set horizontally spaced from the main working surface,