Cleveland C15121 Screw Machine Drill Bit Wire 31 Cobalt

Product Description

The CLEVELAND C15121 is a screw machine length drill bit designed for high-productivity drilling in tight-clearance applications. Built from M42 cobalt high-speed steel, it carries a wire gauge size of 31, corresponding to a decimal diameter of 0.1200 inches. The 135-degree split point and parabolic flute geometry reduce thrust force and improve chip evacuation, making this bit well suited for production drilling in alloy steels and aluminum. The straight-cylindrical shank seats securely in standard drill chucks. Overall length is 1-7/8 inches, keeping the tool rigid and minimizing deflection during short-hole operations.

This drill bit is intended for use on drill presses, CNC machining centers, and hand-held power drills in shop and field environments. The screw machine length designation indicates a shortened flute and body length compared to jobber-length bits, which increases stiffness and accuracy in applications where hole depth is limited. Primary workpiece materials listed for this series include alloy steel and aluminum. The M42 cobalt material grade provides elevated red-hardness, making it appropriate for harder or abrasive workpiece materials that would wear standard HSS tooling prematurely. Machinists, tool-and-die tradespeople, and maintenance mechanics are the typical end users.

Key Features

• M42 cobalt steel construction provides superior heat and wear resistance over standard HSS
• 135-degree split point reduces walking and lowers required thrust force at entry
• Parabolic flute geometry improves chip flow and helps prevent packing in deep cuts
• Web-thinned, parallel-web design reduces cutting resistance and extends tool life
• Screw machine length body maximizes rigidity and minimizes deflection in short-hole work
• Diameter tolerance held to +0.0000 to -0.0005 inches per ASME B94.11M

Compatibility

Designed for use in standard drill chucks accepting a 0.1200-inch straight-cylindrical shank. Suitable for drilling alloy steel and aluminum workpieces. Conforms to ASME B94.11M and ANSI specification designations as part of the Cleveland Series 2175A.

Installation Notes

Installation and use of this drill bit should be performed by qualified machinists or tradespeople familiar with rotating cutting tool safety. Ensure the drill chuck is fully tightened and the workpiece is securely fixtured before beginning any operation. Match spindle speed and feed rate to the workpiece material per published cutting data for cobalt drill bits of this diameter. Inspect the cutting edges for wear or chipping before each use and replace the bit if the point geometry is compromised.