Precision Brand 56508 Mill Key Stock 5/8x5/8x12 in Steel

Product Description

The PRECISION BRAND 56508 is a mill key stock bar cut to 12 inches in length with a 5/8-inch square cross-section. Mill key stock transmits torque between a shaft and a mating component such as a gear, pulley, or sprocket by fitting into a machined keyway. This piece is manufactured from low carbon steel with a plain mill finish, making it well-suited for standard power transmission applications where case hardening or corrosion-resistant coatings are not required. Machinists, millwrights, and maintenance technicians use mill key stock as a raw material, cutting and fitting it to the exact length needed on the job. The plain finish allows for straightforward machining, filing, or grinding to achieve a precise fit.

This key stock is used in industrial, commercial, and light manufacturing settings where rotating shafts require positive mechanical engagement with mounted components. Typical applications include electric motors, pumps, fans, gear reducers, and conveyor drives. The 5/8-inch square profile is a common size for mid-range shaft diameters and is frequently stocked in maintenance shops and repair facilities that service rotating equipment. It ships as a single 12-inch bar, suitable for one or multiple keyway cuts depending on required key length.

Key Features

• 5/8-inch by 5/8-inch square cross-section fits standard 5/8-inch keyways
• 12-inch length provides material for single or multiple keys per bar
• Low carbon steel construction offers good machinability and adequate shear strength for typical power transmission loads
• Plain mill finish requires no surface prep before machining or fitting
• Sold individually as a single bar with no minimum bundle requirement

Compatibility

Designed as a general-purpose mill key stock for use in any standard 5/8-inch keyway application on rotating shafts in motors, pumps, fans, and similar power transmission equipment.

Installation Notes

Installation is typically performed by a millwright or machinist using standard metalworking tools including a hacksaw or cold saw, file, and micrometer to cut and fit the key to the required length and tolerances. Shaft and hub keyways should be free of burrs and debris before fitting. Never force an oversized key into a keyway, as this can crack a hub or distort a shaft. Always de-energize and lock out the equipment per OSHA lockout/tagout procedures before servicing any shaft-mounted component.