Precision Brand 56505 Mill Stock Key Stock 3/8x3/8x12 in 6pc

Product Description

The PRECISION BRAND 56505 is a mill stock key stock bar cut to 0.375 x 0.375 x 12 inches, manufactured from low-carbon steel to ASTM A108 specification. Key stock is the raw material used to fabricate drive keys that lock rotating components — such as pulleys, sprockets, and gears — onto shafts in power transmission assemblies. This piece ships as a pack of six plain-finish bars, giving technicians and machinists ready stock to cut custom-length keys in the field or shop. Hardness is rated at Rockwell B80-90, a range consistent with ASTM A108 cold-drawn carbon steel bar stock.

Mill stock key stock is used wherever a standard square key seat is required. Common applications include industrial conveyor drives, pump and fan shaft assemblies, gearbox output shafts, and general mechanical power transmission setups in commercial and light industrial facilities. The 3/8-inch square cross-section fits shaft and hub keyways sized for 3/8-inch square keys per standard keying practice. Each bar is 12 inches long, providing enough stock to yield multiple shorter keys depending on the specific shaft application.

Key Features

• Low-carbon steel to ASTM A108 specification for consistent machinability and reliable shear strength
• Rockwell B80-90 hardness suitable for standard power transmission key applications
• 3/8 x 3/8 x 12-inch square mill stock — ready to cut to required key length
• Plain finish — no coating to interfere with close-tolerance keyway fits
• Pack of 6 bars for shop stock replenishment or multi-shaft jobs

Compatibility

Designed as a standard mill stock replacement for 3/8-inch square keyway applications in general industrial and commercial power transmission assemblies.

Installation Notes

Key stock installation is typically performed by millwrights, machinists, or maintenance mechanics. Cut the bar to the required key length using a bandsaw, cutoff wheel, or mill, then deburr all edges before fitting. Shut down and lock out the drive system completely before removing or installing any shaft keys. Verify keyway dimensions in both the shaft and hub before cutting to length to ensure proper fit and avoid stress concentrations.