Abstract: A device for preparing a coke oven door includes a frame for securing the door in a working position. A milling machine for machining the door seal includes a gantry coupled to the frame and a milling head coupled to the gantry. The milling head is movable up and down, longitudinally, and transversely relative to the door so as to maintain contact with the door seal. According to one aspect of the invention, a rail is attached to the frame and a rail extension is attached to the gantry. The rail and rail extension cooperate to guide the gantry longitudinally along the door. A rack is attached to the frame and a driven pinion is attached to the milling machine which engages the rack to move the milling machine along the rail and rail extension.