Automatic Knife Sharpener provides a precise, efficient and safe method for honing Microtome Knives up to 140mm in length, equipped with automatic timer 0-60 min. to adjust sharpening time. It ensures a knife edge so perfect that no subsequent stropping is necessary. The knife edge is reconditioned to optimum sharpness which is so major importance to every laboratory, where materials are routinely sectioned for microscopic examinations. The transparent flexi glass cover encloses the entire working mechanism and provides a safe dust and grit free sharpening process. The knife strokes against a high frequency glass honing plate and after three exactly equivalent strokes on one side of knife edge, a cam follower automatically flips the knife and three strokes are honed on other side.