Cleveland C15111 Screw Machine Drill Bit No. 21 Cobalt

Product Description

The CLEVELAND C15111 is a screw machine length drill bit engineered for high-performance drilling in demanding shop and field applications. Built from M42 cobalt high-speed steel, this bit handles heat and wear better than standard HSS tooling, making it well suited for alloy steels and aluminum. It carries a 135-degree split point with web thinning, which reduces thrust and allows the bit to self-center on entry without a pilot hole. The straight-cylindrical shank measures 0.159 inches in diameter with an overall length of 2.125 inches, fitting standard drill chucks used in CNC machines, drill presses, and hand-held drills. The parabolic flute geometry promotes efficient chip evacuation during the cut.

This bit is designed for professionals who need a short, rigid drill for precision work in tight clearances or on automatic screw machines. The screw machine length profile minimizes deflection when drilling alloy steel, aluminum, and similar materials. The Series 2175A cobalt bits are a common choice for machinists, tool-and-die workers, and maintenance mechanics who drill through hard or abrasive materials regularly. The right-hand cut and two-flute design suit standard rotation equipment across production and repair environments.

Key Features

• M42 cobalt construction handles elevated drilling temperatures and abrasive workpiece materials
• 135-degree split point with web thinning reduces thrust and improves self-centering without a center punch
• Parabolic flute geometry with parallel web configuration for efficient chip removal
• Screw machine length body provides added rigidity and reduced deflection versus jobber-length bits
• Straight-cylindrical shank fits standard drill chucks without adapters
• Meets ASME B94.11M standards per ANSI specification designation

Compatibility

Designed as an OEM-style replacement or direct-use screw machine drill bit for standard 3-jaw drill chucks, CNC drilling stations, and automatic screw machines accepting a 0.159-inch straight shank. Suitable for alloy steel and aluminum workpieces per Series 2175A application guidelines.

Installation Notes

Installation is performed by qualified machinists or maintenance mechanics. Secure the shank fully in the drill chuck and confirm runout is within acceptable limits before beginning a cut. Ensure the drilling machine is powered down and locked out before changing or inspecting tooling. Do not exceed the recommended feed and speed parameters for the workpiece material, as cobalt bits can micro-chip under excessive side load.