Starrett 56981 O1 Tool Steel Flat Stock 1/4x3.5x18 in

Product Description

The STARRETT 56981 is an O1 oil-hardening tool steel flat stock bar used in toolmaking, die work, jig fabrication, and precision machining applications. Cut to 0.25 inches thick, 3.5 inches wide, and 18 inches long, this flat stock is supplied in the annealed condition and ready for machining before oil-quench hardening. Thickness and width tolerances are held to +0.0100 to 0.0150 inches, and length tolerance is +0.25 inches. Edge squareness is maintained to 0.003 inches per inch across all edges. The piece weighs approximately 4.46 pounds. Tool and die makers, machinists, and metalworking tradespeople are the primary users of this material.

O1 tool steel flat stock in this size range is well suited to fabricating punches, dies, gauges, fixtures, and cutting tools in both job shop and production tool room environments. The 0.25-inch thickness allows straightforward milling, grinding, and drilling operations prior to heat treatment. Once machined to near-net shape, the bar is oil-quenched to achieve the desired hardness. This size is appropriate for medium-scale tooling work where a wide, flat profile is needed without the cost of a full plate.

Key Features

• AISI Type O1 oil-hardening tool steel composition for predictable heat-treat response
• Tight dimensional tolerances: +0.0100 to +0.0150 inches on thickness and width
• Edge squareness held to 0.003 inches per inch on all edges
• Length tolerance of +0.25 inches allows trim-to-fit flexibility
• Supplied annealed for full machinability before hardening
• Single-piece quantity available with no multi-piece minimum requirement

Compatibility

Designed as a standard AISI O1 oil-hardening tool steel flat bar suitable for general toolroom and die-making applications requiring a 0.25-inch by 3.5-inch cross-section profile.

Installation Notes

Machining and heat treatment of O1 tool steel should be performed by qualified machinists and tool and die makers familiar with proper annealing, hardening, and tempering procedures. Secure the bar properly in a milling vise or on a surface grinder magnetic chuck before any material removal. Oil quenching should follow established shop procedures and applicable safety protocols for flammable quench media. Always relieve internal stress with a tempering cycle immediately after hardening to reduce the risk of cracking.