# US 7,740,522 B2 · Knife sharpener

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- Number: US 7,740,522 B2
- Document ID: US7740522B2
- Status: Granted
- Kind: B2
- Application number: 11/825,845
- Filed: 2007-07-09
- Published: 2009-08-20
- Granted: 2010-06-22
- Earliest claimed: 2007-07-09
- Assignees: National Presto Industries, Inc.
- Inventors: Shane R. Walker
- Web page: https://patentgrep.com/patent/US7740522B2

## CPC

- B24B 3/54: of hand or table knives
- B24B: MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING (grinding of gear teeth B23F, of screw-threads B23G1/36; by electro-erosion B23H; abrasive or related blasting B24C; tools for grinding, buffing or sharpening B24D; polishing compositions C09G1/00; abrasives C09K3/14; electrolytic etching or polishing C25F3/00; grinding arrangements for use on assembled railway tracks E01B31/17); DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS

## Abstract

A motorized knife sharpener includes means of for sharpening heavy, medium, and fine blades at angles appropriate to the cutting edges of such blades.

## Claims

### Claim 1

A knife sharpener, comprising:
a housing assembly enclosing a grinding assembly, the grinding assembly including a motor and a plurality of grinding disc operably coupled to the motor with a rotating axle assembly; and
a plurality of interchangeable blade guides, each interchangeable blade guide being individually connectable to the housing assembly, wherein each interchangeable blade guide corresponds to a specified sharpening application, each interchangeable blade guide including individual grinding stages, each stage corresponding to one of the grinding discs, and wherein each grinding stage defines a presentation angle of a blade to a side grinding surface of the corresponding grinding disc wherein each stage of the blade guide presents a different angle fro the other stages.

### Claim 2 (depends on 1)

The knife sharpener of claim 1, wherein each grinding stage is defined by a left blade slot and a right blade slot, and wherein each of the left and right blade slots includes an inside face and an outside face for establishing a presentation angle of the blade to the side grinding surface.

### Claim 3 (depends on 1)

The knife sharpener of claim 1, said grinding stages including a coarse grinding stage, a medium grinding stage and a fine grinding stage, the coarse grinding stage, medium grinding stage and fine grinding stage facilitating presentation of the blade to the side grinding surface of the corresponding grinding disc at the proper presentation angle.

### Claim 4 (depends on 1)

The knife sharpener of claim 1, wherein the plurality of interchangeable blade guides includes a kitchen blade guide and a sporting blade guide.

### Claim 5

A method for sharpening a blade, comprising:
providing a knife sharpener including a grinding assembly having a plurality of driven grinding discs;
providing a plurality of individually interchangeable blade guides, each interchangeable blade guide including individual grinding stages, each stage corresponding to one of the grinding discs, and wherein each grinding stage defines a presentation angle of a blade to a side grinding surface of the corresponding grinding disc, wherein each stage of the blade guide presents a different angle fro the other stages;
selecting the appropriate blade guide based on the blade to be sharpened;
attaching the selected blade guide to the knife sharpener; and
positioning the blade within the at least one grinding stage on the attached blade guide such that the blade is presented at a desired angle to a side grinding surface of the at least one grinding disc corresponding to the grinding stage.