Scientific Cutting Tools BB258 Radial Relief Boring Bar

Product Description

The SCIENTIFIC CUTTING TOOLS BB258 is a radial relief boring bar machined from submicron-grade solid carbide for demanding internal diameter cutting operations. Designed for right-hand cutting direction, it accepts a 1/4-inch shank and delivers a minimum bore diameter of 0.248 inches with a maximum bore depth of 1 inch. The 2-inch overall length keeps the tool compact for tight setups. The uncoated submicron carbide construction provides excellent rigidity and edge retention in small-bore applications where tool deflection and chatter are primary concerns. Machinists and tool-and-die professionals specify this bar for precision internal turning work on CNC lathes and boring mills.

This boring bar is suited for small-bore internal turning in production and job-shop environments. It performs well in non-ferrous metals, hardened steels, and engineering plastics where tight dimensional tolerances are required. The radial relief geometry reduces rubbing on the bore wall, making it appropriate for finish boring passes where surface finish and roundness are critical. It is installed in a compatible 1/4-inch boring bar holder or quick-change tooling block on a CNC or manual lathe.

Key Features

• Submicron solid carbide blank for superior rigidity and edge retention in small-bore cuts
• Radial relief geometry reduces tool-to-wall contact and minimizes chatter
• Right-hand cutting direction compatible with standard lathe rotation
• Minimum bore diameter of 0.248 inches for tight internal turning work
• Uncoated finish preserves sharp edge geometry for precision finishing passes
• Compact 2-inch overall length suits close-clearance setups

Compatibility

Designed as an OEM-style replacement and standard-fit boring bar for 1/4-inch boring bar holders used on CNC lathes, manual engine lathes, and boring mills requiring right-hand internal turning tooling.

Installation Notes

Installation is performed by a machinist or toolroom professional. Secure the 1/4-inch shank fully in the holder to the recommended overhang length specified by the tooling system manufacturer, as excessive overhang increases deflection in small-bore applications. Power down and lock out the spindle before inserting or removing the bar from the holder. Avoid side-loading the carbide shank during tightening, as solid carbide is brittle and susceptible to fracture under clamp misalignment.