Abstract: A metal machining device includes a pair of longitudinally movable gantries and a connecting transverse bridge which mounts carriages which carry machining tools. A computer numerical control unit is fixedly mounted adjacent one end of the bridge and is connected to supplemental electronic circuits. The transverse tool-carrying bridge is formed as a generally hollow heavy-walled closed box-beam which has mounted therein at least part of the supplemental electronic circuitry. A beam side-wall is provided with a plurality of doors which open to permit access to a plurality of circuit-holding drawers. When the doors are closed, the bridge forms a unitary hollow housing containing the supplemental electronic circuitry which serves to mechanically and electronically isolate them and substantially reduce the radiation of electronic noise therefrom to the computer.