Starrett 56987 O1 Tool Steel Flat Stock 5/16x5/16x18 in

Product Description

The STARRETT 56987 is an O1 oil-hardening tool steel flat stock bar sized at 5/16 inches thick by 5/16 inches wide by 18 inches long. Made from AISI Type O1 tool steel, it is supplied in the annealed (soft) condition, ready for machining, grinding, and shaping before oil-quench hardening. O1 is a general-purpose tool steel known for its dimensional stability during heat treatment and its ability to hold a keen edge after hardening. Licensed machinists, toolmakers, and die makers use this stock to fabricate punches, dies, gauges, and cutting tools. The bar ships at 0.5 pounds.

This flat stock is suited for short-run tooling and repair work in job shops, maintenance departments, and tool rooms. The 18-inch length allows multiple blanks to be cut from a single piece, reducing material waste on small tooling projects. Thickness and width are both held to a plus tolerance of 0.0100 to 0.0150 inches, making incoming inspection straightforward. Edge squareness is held to 0.003 inches per inch across all edges, which simplifies layout and reduces setup time at the surface grinder or mill.

Key Features

• AISI Type O1 oil-hardening tool steel for predictable heat-treatment response
• 5/16 inches x 5/16 inches cross-section in an 18-inch working length
• Thickness and width tolerance: plus 0.0100 to 0.0150 inches for consistent stock removal
• Edge squareness: 0.003 inches per inch on all edges for reliable layout reference
• Length tolerance: plus 0.2500 inches — full usable length guaranteed
• Supplied annealed; machines with standard HSS or carbide tooling before hardening

Compatibility

Designed as a standard AISI O1 oil-hardening tool steel flat stock bar suitable for fabricating punches, dies, cutting tools, gauges, and general toolroom components where an oil-quenched, high-hardness finish is required.

Installation Notes

Toolmakers and machinists work this bar stock on mills, lathes, and surface grinders using standard HSS or carbide tooling while the steel is in the annealed condition. Final hardening requires controlled heat treatment and oil quench per AISI O1 specifications — this process should be performed only by personnel trained in tool steel heat treatment. Allow the finished part to temper immediately after quenching to reduce the risk of cracking. Follow applicable shop safety protocols when handling cutting fluids and heat-treatment equipment.