Starrett 56999 O1 Tool Steel Flat Stock 3/8x1/2x18 in

Product Description

The STARRETT 56999 is an O1 oil-hardening tool steel flat stock bar used in toolmaking, die making, and precision machining applications. It is manufactured from AISI Type O1 tool steel, a widely used oil-hardening grade known for its dimensional stability and ease of machining in the annealed state. This bar measures 0.375 inches thick, 0.5 inches wide, and 18 inches long, with a thickness tolerance of +0.010 to +0.015 inches, a width tolerance of +0.010 to +0.015 inches, and a length tolerance of +0.250 inches. Edge squareness is held to 0.003 inches per inch across all edges. The part weighs approximately 0.96 pounds.

This flat stock is suited for fabricating punches, dies, gauges, fixtures, and cutting tools in job shop and tool-and-die environments. It is typically purchased by machinists, tool and die makers, and precision metalworking professionals who require a consistent pre-cut blank that can be machined, ground, and then oil-quenched to final hardness. The 18-inch length provides a practical working blank for a range of small to mid-sized tooling components.

Key Features

• AISI Type O1 oil-hardening tool steel for predictable heat treatment response
• Thickness: 0.375 inches with +0.010 to +0.015 inch tolerance
• Width: 0.5 inches with +0.010 to +0.015 inch tolerance
• Length: 18 inches with +0.250 inch tolerance
• Edge squareness held to 0.003 inches per inch on all edges
• Ready-to-machine annealed flat bar format

Compatibility

Designed as a standard O1 oil-hardening tool steel flat stock blank suitable for general toolmaking, die making, and precision fixture fabrication where AISI Type O1 material is specified.

Installation Notes

Machining and grinding of O1 tool steel flat stock should be performed with appropriate cutting fluids and speeds for tool steel grades. Heat treatment, including oil quenching, should be carried out by qualified personnel following established metallurgical procedures and applicable shop safety standards. Always handle ground and hardened stock edges with care to avoid chipping. Consult the material specification sheet for recommended hardening temperatures and quench media before heat treating.