Patent ID: 8288678

Claim:
A device for maintaining cutting edge of a shaping member at a constant distance from a reference surface of an article as the cutting edge and the reference surface move relative to one another, the device comprising: a hollow tube having a first end and an opposite second end, the second end of the tube having increasing wall thickness as distance from the second end of the tube increases to provide the second end of the tube with an internal concave end portion, wherein the second end of the tube and the cutting edge of the shaping member have a predetermined spaced relationship to one another; a constant force applying arrangement for connecting the first end of the tube to a support member; a surface follower having a first major surface and an opposite second major surface, the second major surface of the surface follower sized and shaped to fit into the internal concave end portion of the second end of the tube, the surface follower having a plurality of passageways, each of the passageways having an exit opening at the first major surface of the surface follower, wherein the surface follower and the tube are not connected to one another and are free to move toward and away from one another; a solid plate mounted within the tube between the first end and the second end of the tube to provide the tube with a chamber between the second end of the tube and the plate; an inlet for moving a gas into the chamber of the tube, wherein when the gas moves into the chamber and the tube is positioned to have the first major surface of the surface follower in facing relationship and adjacent to the reference surface, a first portion of the gas moves between outer surface portions of the second major surface of the surface follower and inner surface portions of the second end of the tube to provide a first gas bearing having a first thickness between outer surface portions of the second major surface of the surface follower and the inner surface portions of the second end of the tube, and a portion of the gas moves through the passageways of the surface follower to provide a second gas bearing having a second thickness between the first major surface of the surface follower and the reference surface, wherein the cutting edge of the shaping member is at a predetermined distance from the reference surface, and the surface follower and the tube are spaced from one another by the first gas bearing and out of contact with one another, and wherein curvatures of the reference surface of the article expand and contract the constant force arrangement to maintain the first and second thicknesses of the first and the second gas bearings, respectively, constant as the surface follower moves over the reference surface to maintain the cutting edge of the shaping member at a constant distance from the reference surface of the article.