Hertel 66691973 Drill Bit Size 21 Cobalt Tin 135 Deg

Product Description

The HERTEL 66691973 is a screw machine length drill bit designed for high-speed, short-reach drilling applications in metal fabrication, machining, and general industrial work. It is manufactured from cobalt steel with a titanium nitride (TiN) coating for extended wear resistance and improved tool life at elevated temperatures. The bit is sized at wire gauge No. 21, corresponding to 0.1590 inches in diameter, and features a 135-degree split point for self-centering entry without a center punch. Overall length is 2.125 inches with a flute length of 1.0625 inches. The straight-cylindrical shank fits standard drill chucks. This is a heavy-duty grade bit suited for machinists, tool-and-die technicians, and maintenance professionals working in production environments.

Screw machine length bits are shorter than jobber-length bits, providing greater rigidity and reduced deflection in drill press, CNC, and turret lathe applications. The No. 21 wire gauge size is commonly used for close-tolerance hole sizing, tapping preparation, and precision drilling in ferrous and non-ferrous metals. The TiN coating reduces friction and resists built-up edge, making this bit effective in stainless steel, alloy steel, cast iron, and similar hard materials. It is a single-piece unit sold individually.

Key Features

• Cobalt steel construction for heat resistance and hardness retention in demanding materials
• TiN coating reduces friction and extends cutting edge life
• 135-degree split point enables self-centering entry and reduces thrust force
• Screw machine length body provides added rigidity and reduced deflection versus jobber-length bits
• Web-thinned parallel web design improves chip evacuation and cutting efficiency
• Right-hand spiral flute, straight-cylindrical shank fits standard drill chucks without modification

Compatibility

Designed for use in drill presses, CNC machining centers, turret lathes, and hand-held drill motors accepting a straight-cylindrical shank of 0.1590 inches in diameter. Suitable for drilling ferrous and non-ferrous metals within the 0.1500 to 0.2000 inch diameter range class.

Installation Notes

Installation and use should be performed by qualified machinists or maintenance technicians familiar with drill bit selection and machine operation. Secure the shank fully in the drill chuck and verify runout before beginning a cut. Ensure the workpiece is properly clamped before drilling to prevent rotation or movement. Follow applicable shop safety standards and machine-specific operating procedures when running cobalt-coated tooling at rated speeds.