Starrett 54166 O1 Tool Steel Flat Stock 9/16 X 9/16 X 18 in

Product Description

The STARRETT 54166 is an O1 oil-hardening tool steel flat stock bar ground to close dimensional tolerances for use in tool and die making, fixture building, and precision machining applications. Manufactured to AISI Type O1 material specification, this flat stock measures 9/16 inches thick, 9/16 inches wide, and 18 inches long, with a weight of 1.61 pounds. Thickness and squareness tolerances are held to plus or minus 0.001 inches, making it suitable for applications where dimensional consistency is critical before and after hardening. Licensed machinists, toolmakers, and die makers are the primary users of this stock.

This flat stock is used in tool rooms, job shops, and maintenance departments where O1 tool steel is specified for punches, dies, gauges, jigs, and general tooling components. O1 is a low-alloy oil-quench steel known for good machinability in the annealed state and for achieving high surface hardness after heat treatment. It is appropriate for both light-production tooling and prototype work where tight pre-hardened dimensions reduce post-grind time. The 18-inch length provides a useful working blank for most small-to-medium tooling applications.

Key Features

• AISI Type O1 oil-hardening tool steel — good machinability in annealed state, high hardness after quench
• Thickness tolerance of plus or minus 0.001 inches for consistent stock removal planning
• Width tolerance of 0.000 to minus 0.005 inches — never over-width
• Length tolerance of plus 0.250 inches, minus 0 — full usable length guaranteed
• Squareness held to 0.003 inches per inch on all edges
• Ready-to-machine flat stock requiring no additional straightening or surface preparation under normal conditions

Compatibility

Designed as a standard O1 oil-hardening tool steel flat stock blank suitable for general tool room and die shop use where AISI Type O1 material specification is required.

Installation Notes

Machining and heat treatment of O1 tool steel should be performed by qualified toolmakers or machinists familiar with oil-quench hardening procedures. Always allow stock to reach a uniform temperature before heat treatment and follow established quench practices to minimize distortion. Secure workpieces properly during cutting and grinding operations and use appropriate coolant to prevent localized overheating that can alter the steel microstructure. Wear appropriate PPE when cutting, grinding, or heat treating tool steel.