Buy Key Stock Online in Australia
What is a Woodruff key?
A Woodruff key is a semi-circular (half-moon) shaped key used to lock a hub onto a shaft, transferring torque between the two. The flat side of the key sits in a milled pocket in the shaft, and the rounded top engages a straight slot in the hub. The semi-circular shape lets the key tilt slightly to compensate for any taper in the keyway, making it easier to fit on small or angled shafts. AIMS Industrial stocks Woodruff keys and parallel sunk keys in metric and imperial sizes.
What is the difference between a Woodruff key and a parallel key?
A parallel (sunk) key is a rectangular bar that fits into a straight keyway machined into both shaft and hub — used on most general drives. A Woodruff key is semi-circular and sits in a milled pocket in the shaft, used where a parallel keyway can't be cut (small shafts, tapered shafts, automotive flywheels, magneto drives).
How do you choose the right key stock size?
Key stock cross-section is selected based on shaft diameter — the larger the shaft, the larger the key section. Standard sizing tables match shaft diameter ranges to square or rectangular key cross-sections. Length is cut from the key stock bar to suit the hub width, usually with a small clearance at each end.
Key Stock Sizes — Quick Reference
Key stocks are precision-ground bar stock used to machine keys for shaft-to-hub connections (locking pulleys, sprockets, sheaves and gears onto rotating shafts). Both Woodruff (half-moon) keys and parallel sunk (straight) keys are produced from key stock. AIMS stocks metric and imperial sizes in hardened steel. Manufactured to AS 1654 / ISO 773 dimensional standards.
| Shaft Ø Range | Square Key (mm × mm) | Rectangular Key (W × H) | Standard |
|---|---|---|---|
| 10 - 12 mm | 4 × 4 mm | 4 × 3 mm | AS 1654 / ISO 773 |
| 12 - 17 mm | 5 × 5 mm | 5 × 3 mm | AS 1654 / ISO 773 |
| 17 - 22 mm | 6 × 6 mm | 6 × 4 mm | AS 1654 / ISO 773 |
| 22 - 30 mm | 8 × 8 mm | 8 × 5 mm | AS 1654 / ISO 773 |
| 30 - 38 mm | 10 × 10 mm | 10 × 6 mm | AS 1654 / ISO 773 |
| 38 - 44 mm | 12 × 12 mm | 12 × 7 mm | AS 1654 / ISO 773 |
| 44 - 50 mm | 14 × 14 mm | 14 × 8 mm | AS 1654 / ISO 773 |
| 50 - 58 mm | 16 × 16 mm | 16 × 9 mm | AS 1654 / ISO 773 |
| 1/4" imperial | 1/4" × 1/4" | — | ANSI B17.1 |
| 5/16" imperial | 5/16" × 5/16" | — | ANSI B17.1 |
| 3/8" imperial | 3/8" × 3/8" | — | ANSI B17.1 |
Key stock is supplied in 300 mm (or 12") lengths and cut to suit the hub width. Available in carbon steel ZP and 304SS. For complete keyway design — parallel vs Woodruff key selection, shaft sizing, keyway machining — see our keyways & keys guide. For complete key steel range, see key steel. For taper-lock alternatives to keyed connections, see taper lock bushes.
Find precision key stocks for reliable power transmission at AIMS Industrial. Our range includes Woodruff keys and parallel sunk keys in both imperial and metric sizes, engineered to lock gears, sprockets, sheaves and other rotating components to shafts with a positive no-backlash fit. Manufactured from hardened steel for consistent strength and wear resistance, these removable keys simplify installation and maintenance across industrial, agricultural and marine applications. Search by shaft diameter, keyway width or standard to quickly locate the exact size you need. We ship across Australia and internationally, with free shipping on orders over $299 for Adelaide, Brisbane, Melbourne, Canberra, Perth and Sydney. Buy single pieces or bulk quantities for workshops and production lines, and rely on fast dispatch and accurate sizing charts to keep downtime to a minimum. Browse our Key Stocks collection now to select the correct Woodruff or parallel sunk key and ensure secure, efficient coupling for your machinery.