Knife Sharpening API

Knife-sharpening maths as an API, computed locally and deterministically — the bevel and angle numbers a sharpener, cook or knifemaker sets a stone to. It uses the symmetric V-edge model: the bevel endpoint takes the blade thickness and a per-side (or inclusive) angle and returns the bevel face width = (thickness ÷ 2) ÷ sin(per-side angle), with the inclusive angle as twice the per-side — so a 2 mm blade ground at 15° per side has a 3.86 mm bevel and a 30° edge, and at a 40° inclusive (20° per side) a 2.92 mm bevel. The angle endpoint runs it in reverse for the marker (Sharpie) method: colour the edge, take one stroke, measure the shiny bevel, and per-side angle = asin((thickness ÷ 2) ÷ bevel width) tells you the angle you are actually holding. The recommend endpoint gives sensible inclusive-angle ranges by use — about 12–17° for razors, 20–30° for Japanese kitchen knives, 30–40° for Western chef’s and EDC, 40–50° for outdoor and hard use, 45–65° for axes — and converts any chosen inclusive angle to per-side and back. Everything is computed locally and deterministically, so it is instant and private. Ideal for knife, kitchen, EDC, bushcraft, woodworking and sharpening app developers, sharpening-jig and edge-geometry tools, and maker software. Pure local computation — no key, no third-party service, instant. Symmetric V-edge model, mm and degrees. Live, nothing stored. 3 compute endpoints.