Starrett 58900 O1 Tool Steel Flat Stock 1/4x3/8x36 in

Product Description

The STARRETT 58900 is an O1 oil-hardening tool steel flat stock bar sized at 0.25 inches thick, 0.375 inches wide, and 36 inches long. Made from AISI Type O1 tool steel, this flat stock is used by machinists, toolmakers, and die makers who need a machinable, grindable steel bar that can be hardened in oil for final tooling applications. It arrives in the annealed (soft) state, allowing it to be machined, filed, or ground to shape before heat treatment. Tight tolerances — plus or minus 0.001 inches on thickness — make it suitable for precision tooling work where dimensional accuracy matters before and after hardening.

O1 tool steel flat stock in this size is commonly used to fabricate punches, dies, gauges, jigs, fixtures, and cutting tools in job shops, tool rooms, and manufacturing environments. The 36-inch bar length provides sufficient stock for multiple smaller tool blanks from a single piece. Trade professionals working in precision machining, mold making, and general tooling fabrication will find this size appropriate for small-profile tooling components requiring a hardened working surface after heat treatment.

Key Features

• AISI Type O1 oil-hardening tool steel — machines and grinds in the annealed state, hardens in oil quench
• Thickness tolerance of plus or minus 0.001 inches for consistent fit in precision tooling applications
• Width tolerance of 0.000 to minus 0.005 inches, length tolerance of plus 0.015 inches
• Edge squareness held to 0.003 inches per inch across all edges
• 36-inch length yields multiple tool blanks from a single bar
• Weighs 0.96 pounds per bar

Compatibility

Designed as a standard O1 oil-hardening tool steel flat bar suitable for general toolroom and precision machining applications where AISI Type O1 material specification is required.

Installation Notes

O1 tool steel flat stock is worked by machinists and toolmakers using conventional milling, grinding, and sawing equipment while in the annealed state. Heat treatment to final hardness should be performed by qualified personnel following established oil-quench procedures for AISI O1 steel. Handle edges with care, as ground surfaces can be sharp. Store flat to prevent distortion before and after machining.