A file having a convex surface with a multiplicity of spaced depressions therein. At least some of the depressions are spaced from all the others and include an adjacent upset cutting lip. The surface of each of at least some of the depressions defines an arc in one plane; the arc being coextensive with the gullet of that depression; and the length of the chord from one end of the gullet to the other being greater than the width of the depression in an orthogonal plane.
A polishing apparatus for reducing the roughness and abrasive shedding of coated tapes comprises a cylinder having coaxial channels or grooves of various forms, which are advantageously thread-like. Axial grooves may be additionally provided.
