Starrett 56996 O1 Tool Steel Flat Stock 5/16x4x18 in

Product Description

The STARRETT 56996 is an O1 oil-hardening tool steel flat stock bar sized at 5/16 inches thick, 4 inches wide, and 18 inches long. O1 is an AISI-designated oil-hardening tool steel valued for its consistent response to heat treatment, good machinability in the annealed state, and ability to hold a sharp edge after hardening. This bar ships in the annealed condition, making it suitable for machining, grinding, and layout work before hardening. Machinists, toolmakers, and die makers use this stock to fabricate punches, dies, gauges, jigs, and cutting tools. The controlled tolerances on all three dimensions make it a reliable choice for precision toolroom applications.

This flat stock is used in toolrooms, machine shops, and maintenance departments for fabricating small tooling and fixtures. Its 4-inch width and 18-inch length provide enough material for a range of toolmaking tasks without requiring a full-length bar. The oil-hardening process produces minimal distortion compared to water-hardening grades, which is important when close final dimensions are required after heat treatment. This stock is appropriate for low-to-medium production tooling in both job shop and industrial manufacturing environments.

Key Features

• AISI Type O1 oil-hardening tool steel composition for predictable heat treatment response
• Annealed condition allows machining and grinding prior to hardening
• Thickness tolerance: plus 0.0100 to 0.0150 inches
• Width tolerance: plus 0.0100 to 0.0150 inches
• Length tolerance: plus 0.2500 inches
• Edge squareness: all edges held to 0.003 inches per inch

Compatibility

Designed as a general-purpose O1 oil-hardening tool steel flat bar for toolroom fabrication of punches, dies, gauges, and precision fixtures requiring an oil-quench hardening process.

Installation Notes

Cutting, grinding, and machining should be completed in the annealed state before hardening. Heat treatment must be performed by qualified personnel following established procedures for O1 tool steel; improper quenching or temperature control can cause cracking or distortion. Always wear appropriate PPE when cutting or grinding tool steel. Follow applicable shop safety codes and equipment manufacturer guidelines during all machining and heat-treating operations.