The Geometry of Specific Knife Shapes — Tips for Tricky Profiles

Not all knives are long, straight, and double-beveled. Different shapes require adapting your technique, and understanding why makes the adaptation intuitive rather than arbitrary.

The Curved Belly of a Chef's Knife

A Western chef's knife has a distinctive belly — the edge curves up toward the tip. When sharpening this curve, you need to sweep the knife across the stone while simultaneously rotating the handle downward as you reach the tip, so the curved part of the edge maintains consistent contact with the stone at a consistent angle.

Think of it as rolling the knife through the stroke rather than sliding it. It takes practice, but once you have it, it becomes fluid and natural. The tip itself — the last centimeter — needs a slightly different motion: almost a vertical sweep, with the blade nearly perpendicular to the stone's length.

The Sheepsfoot and Wharncliffe Profile

These profiles have very straight edges with little or no curve, making them easier to sharpen in some ways — the angle doesn't need to vary across the stroke — and harder in others (the flat profile makes it easy to inadvertently round the edge or miss the very tip and heel).

The Tanto Profile

Tanto knives have a secondary blade point — the edge runs straight to a distinct angled "belly" near the tip before meeting the spine. You have to sharpen this secondary bevel as a distinct section, treating the two portions of the edge as separate edges with potentially different bevel angles.

Convex-Beveled Edges

Some knives — many hunting knives and Scandinavian "scandi grind" knives — have a primary bevel that extends all the way to the spine with no secondary bevel. These are sharpened on the stone at the full primary angle. The scandi grind is particularly forgiving for beginners because the large, flat primary bevel registers directly on the stone, making angle control easy.

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