Cleveland C70281 Letter B Screw Machine Drill Bit Hss

Product Description

The CLEVELAND C70281 is a screw machine length drill bit sized to Letter B (0.2380 inches) and built from high-speed steel (HSS) with a bright, uncoated finish. The 135-degree split point reduces thrust at entry and self-centers without a pilot hole, making it well suited for production drilling in alloy steel and aluminum. The web-thinned, parallel-web design keeps cutting action consistent across the full depth. At 2.5 inches overall length, this stub-length bit delivers rigidity and reduced deflection compared to jobber-length alternatives. It is a heavy-duty grade bit conforming to ASME B94.11M and NAS 907 Type C standards.

This bit is intended for use in screw machine operations, CNC drilling centers, drill presses, and hand-held power tools where a compact, rigid bit is required. Primary workpiece materials include alloy steel and aluminum. The straight cylindrical shank diameter matches the bit diameter at 0.2380 inches, allowing direct chuck mounting without adapters. The two-flute spiral design provides efficient chip evacuation in both ferrous and non-ferrous materials. Typical users include machinists, tool-and-die technicians, and maintenance professionals working in production or job-shop environments.

Key Features

• Letter B size — 0.2380 inches diameter with a tolerance of +0.0000 to -0.0007 inches
• 135-degree split point for self-centering entry and reduced thrust
• High-speed steel construction with bright, uncoated finish
• Screw machine (stub) length — 2.5 inches OAL for maximum rigidity and minimal deflection
• Web-thinned parallel web for consistent cutting performance
• Conforms to ASME B94.11M and NAS 907 Type C specification

Compatibility

Designed as an OEM-style replacement or direct-use screw machine drill bit for production drilling applications in alloy steel and aluminum, compatible with standard three-jaw chucks accepting a 0.2380-inch straight cylindrical shank.

Installation Notes

Installation and use should be performed by qualified machinists or maintenance technicians familiar with drill press and CNC machine operation. Secure the shank firmly in the chuck and verify concentricity before drilling. Always power down and lock out the machine before changing bits. Use appropriate cutting fluid recommendations for the workpiece material to extend tool life and maintain hole tolerance.