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.
People Also Ask — Key Stocks (Key Steel)
Q: What's key stock used for?
Key stock is square or rectangular bar stock used to make machine keys — the components that lock a pulley, sprocket, gear, or coupling onto a shaft so they rotate together without slipping. Standard key stock comes in lengths ready to cut to size for parallel keys, gib head keys, or woodruff keys. AIMS supplies key stock to AS 2938 for parallel keys.
Q: What sizes of key stock should I keep on hand?
Common metric sizes match shaft diameter ranges: 5mm x 5mm (shafts ~20-22mm), 6mm x 6mm (~22-30mm), 8mm x 7mm (~30-38mm), 10mm x 8mm (~38-44mm), 12mm x 8mm (~44-50mm), 14mm x 9mm (~50-58mm), 16mm x 10mm (~58-65mm). Imperial sizes match imperial shafts in the same way. The shaft diameter determines the standard key size per the AS or ISO key spec.
Q: What's the material of standard key stock?
Standard parallel keys are typically C45 (medium carbon steel) or similar — adequate for general industrial transmission. For higher torque or shock-load applications, choose hardened or tempered key stock, or upgrade to 4140 alloy steel keys for heavy industrial drives. Match the key material strength to the application — under-spec keys shear before failing the shaft and protect the more expensive shaft and hub.
Q: Square key vs rectangular key — which do I use?
Most parallel keyed drives use square key stock (5x5, 6x6, 8x8 etc) — the cross-section matches the keyway in shaft and hub. Rectangular key stock (8x7, 10x8, 12x8 etc) is used where the keyway is shallower in the hub than in the shaft — common in pre-bored taper-bored pulleys and some standard hubs. Check the keyway dimensions in both the shaft and the hub before cutting key length.
Q: How do I cut key stock to length?
Mark the required length, then cut with a hacksaw, bandsaw, or angle grinder with a cutting disc. The key length should match the keyway length in the hub (usually slightly shorter than the keyway to avoid bottoming out). File or grind the cut end square. For production work, drop-saw with a metal-cutting blade or an abrasive cutoff saw gives faster, cleaner cuts than hand sawing.