US Patent 7517275 Apparatus for precision steeling/conditioning of knife edges

A multi-stage sharpener includes at least one motor driven abrasive sharpening stage and one non-motor driven conditioning stage. The conditioning stage has a non-abrasive hardened surface and at least one precision knife guide which has a planar guide surface for creating a microscopic serration along the edge of a blade which had been sharpened in the first stage sharpening station. The sharpener may also include a third stage motor driven finishing stage. Alternatively, the conditioning stage can be incorporated as the knife edge modifying stage of a manual sharpener.