Starrett 57240 O1 Tool Steel Flat Stock 5/16x1-3/4x36 in

Product Description

The STARRETT 57240 is an O1 oil-hardening tool steel flat stock bar intended for toolmakers, machinists, and die makers who require tight-tolerance raw material for custom tooling, punches, dies, and gauges. The bar measures 5/16 inch thick, 1-3/4 inches wide, and 36 inches long, weighing 5.58 pounds. Thickness tolerance is held to plus or minus 0.001 inches, making this stock suitable for precision applications where dimensional consistency from bar to bar is critical. The material conforms to AISI Type O1 oil-hardening specification and is supplied in the annealed condition, ready for machining before heat treatment.

This flat stock is used in tool and die shops, maintenance departments, and production environments where custom tooling must be fabricated in-house. Typical applications include blanks for punches, forming dies, cutting tools, jigs, fixtures, and wear parts. The 36-inch length allows multiple parts to be laid out and cut from a single bar. It is appropriate for both one-off tool room work and small production runs where O1 grade toughness and oil-quench hardenability are specified.

Key Features

• AISI Type O1 oil-hardening tool steel, supplied in annealed condition for machining
• Thickness tolerance: plus or minus 0.001 inches for consistent stock-to-stock fit
• Width tolerance: 0.000 to minus 0.005 inches
• Length tolerance: plus 0.015 inches
• Edge squareness: all edges held to 0.003 inches per inch
• 36-inch bar length allows multiple part blanks from a single piece

Compatibility

Designed as a general-purpose O1 tool steel flat stock for fabrication of custom tooling, dies, and precision components in tool room and maintenance machining applications.

Installation Notes

Machining and heat treatment of tool steel stock should be performed by qualified machinists or toolmakers familiar with O1 oil-hardening procedures. Standard machining operations apply in the annealed state; follow the material supplier heat treat guidelines for hardening and tempering cycles before putting finished tools into service. Wear appropriate PPE when sawing, grinding, or milling tool steel. Inspect bar dimensions before layout to confirm stock is within tolerance for the intended application.