Abstract: A tool for simultaneously machining two opposing edges of the end face of a horizontal plate is disclosed. The tool comprises two machining means, rotatable about a vertical axis; the lower machining means is at a fixed vertical position, while the vertical position of the upper machining means varies in conformance with the top surface of the plate, by being part of a vertically sliding subassembly that comprises one or more rollers and means to press the subassembly downward so that the rollers continuously touch the top surface of the plate.

Abstract: A rotary device for simultaneously treating two or more regions of a workpiece, which includes a rotatable shaft having an externally threaded portion. Mounted on the shaft, connected to the shaft or integrally formed with it, is a first tool. The device further includes a second tool which is mounted on the externally threaded portion of the shaft. The second tool is internally threaded so that rotation of the second tool axially displaces the second tool along the shaft, thereby changing the spacing between the two tools. The device further includes a set screw or similar mechanism for fixing the second tool at a location along said externally threaded portion of said shaft.