Abstract: A tool (15) to be ground is mounted in a vertical position to the upper end of a vertically oriented piston (21). The lower end of the piston (21) is received into the open end of a cylinder (22). Radial fluid bearings (28, 29) are pressurized to permit rotational and longitudinal movement of the piston (21) with respect to the cylinder (22). Pressurized fluid is delivered to the piston (21) to exert a force on the piston (21) that nearly counterbalances the combined weight of the piston (21) and the tool (15). Additional fluid pressure or some other suitable force is applied to move the piston (21) and the tool (15) axially upwardly. At the end of the upward stroke, the additional force on the piston (21) is removed to allow said combined weight to move the piston (21) and the tool (15) downwardly. During the upward stroke, the downward stroke, or both the upward and the downward strokes, a grinding wheel (13) is held in a fixed position to contact a side surface of tool (15).

Abstract: A tool (15) to be ground is mounted in a vertical position to the upper end of a vertically oriented piston (21). The lower end of the piston (21) is received into the open end of a cylinder (22). Radial fluid bearings (28, 29) are pressurized to permit rotational and longitudinal movement of the piston (21) with respect to the cylinder (22). Pressurized fluid is delivered to the piston (21) to exert a force on the piston (21) that nearly counterbalances the combined weight of the piston (21) and the tool (15). Additional fluid pressure or some other suitable force is applied to move the piston (21) and the tool (15) axially upwardly. At the end of the upward stroke, the additional force on the piston (21) is removed to allow said combined weight to move the piston (21) and the tool (15) downwardly. During the upward stroke, the downward stroke, or both the upward and the downward strokes, a grinding wheel (13) is held in a fixed position to contact a side surface of tool (15).