Abstract: An apparatus for simultaneously machining three circumferential surfaces of a circular workpiece. The device includes a frame having a support for securing the workpiece thereto. A center tube rotatably supported by the frame extends into the interior of the circular workpiece and supports diametrically opposed spindle arms. One spindle arm supports a pair of rotatable grinding wheels disposed to grind parallel horizontal surfaces on the workpiece. The other spindle arm supports a rotatable grinding wheel for machining the interior radial surface of the workpiece. The position of the grinding wheels may be accurately controlled by dovetail slides and handwheels. The grinding wheels are rotated with respect to their spindle arms and the center tube is rotated so as to move the grinding wheels about the circumference of the workpiece to simultaneously machine each of the three surfaces of the workpiece.

Abstract: An apparatus for simultaneously machining three circumferential surfaces of a circular workpiece. The device includes a frame having support for securing the workpiece thereto. A center tube rotatably supported by the frame extends into the interior of the circular workpiece and supports diametrically opposed spindle arms. One spindle arm supports a pair of rotatably grinding wheels disposed to grind parallel horizontal surfaces on the workpiece. The other spindle arm supports a rotatable grinding wheel for machining the interior radial surface of the workpiece. The position of the grinding wheels may be accurately controlled by dovetail slides and handwheels. The grinding wheels are rotated with respect to their spindle arms and the center tube is rotated so as to move the grinding wheels about the circumference of the workpiece to simultaneously machine each of the three surfaces of the workpiece.