Precision Brand 56503 Key Stock 0.25x0.25x12 in Steel 6pc

Product Description

The PRECISION BRAND 56503 is a mill stock key stock bar made from low-carbon steel with a plain finish, supplied in a 6-piece package. Key stock is a semi-finished shaft component used to transmit torque between a rotating shaft and a hub, gear, pulley, or sprocket by fitting into mating keyways on both parts. This bar measures 0.25 inches wide by 0.25 inches high by 12 inches long and meets ASTM A108 material specification. It is sized to be cut to length on the job, making it a practical stocking item for maintenance shops, machine shops, and industrial service applications. Hardness is rated at Rockwell B80-90, providing reliable shear strength under normal drive loads.

Mill stock key stock of this profile is commonly used in light-duty to medium-duty power transmission assemblies found in HVAC fan shafts, pump drives, conveyor systems, and general industrial equipment. The 0.25 x 0.25 inch square profile is one of the most frequently encountered sizes in fractional inch shaft keyways. Machinists, millwrights, and maintenance technicians typically select this stock when replacing worn or sheared keys or when fitting new assemblies where the key must be trimmed to a precise finished length.

Key Features

• Low-carbon steel construction meets ASTM A108 material specification
• Rockwell B80-90 hardness for consistent shear resistance
• Square 0.25 x 0.25 inch profile fits standard fractional inch keyways
• 12-inch bar length allows on-site cutting to required finished length
• Plain finish with no coating — ready for direct installation or light dressing
• Sold in a 6-piece package to support stocking and repeat-use applications

Compatibility

Designed as a mill stock replacement for standard 0.25 x 0.25 inch square keyway applications in fractional inch power transmission assemblies. No specific OEM equipment compatibility was stated in the product data.

Installation Notes

Key stock installation is typically performed by machinists or millwrights during shaft assembly or drive repair. De-energize and lock out all equipment before removing or installing keys. The bar should be cut to finished length using appropriate metal-cutting tools and deburred before fitting into the keyway. Do not force a key into a keyway that requires excessive pressure, as this may indicate an incorrect profile size or debris in the keyway.