🔑 Keyseat & Keyway Reference

Why Keyseat Dimensions Matter

Keyseats (keyways) transmit torque between a shaft and hub — pulleys, gears, and couplings all rely on properly sized keys. The width, depth, and length must match standard key sizes, or the key will rock, shear, or prevent assembly.

• ANSI and ISO standards define key width based on shaft diameter — a 1-inch shaft uses a 1/4-inch square key
• Keyseat depth is measured from the shaft surface, not the center — the cutter depth setting accounts for the arc of the shaft
• Woodruff keys use a semicircular pocket instead of a slot — different cutter geometry and depth calculations

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