Hertel 66691221 Cobalt Screw Machine Drill Bit 5/64 in

Product Description

The HERTEL 66691221 is a cobalt screw machine length drill bit designed for high-speed, short-reach drilling in metal and hard materials. At 5/64 inches (0.0781 inches) in diameter with a 135-degree split point, it starts on center without a pilot hole and reduces walking on hard surfaces. The TiN (titanium nitride) coating extends tool life by increasing surface hardness and reducing friction. With an overall length of 1-11/16 inches and a flute length of 11/16 inches, this stub-length bit provides increased rigidity compared to jobber-length alternatives. It is installed and used by machinists, HVAC technicians, plumbers, and electricians who drill in tight or confined spaces requiring precise, controlled entry.

This bit is suited for screw machine operations, CNC setups, and hand-held drilling applications where stub length reduces deflection. The straight cylindrical shank fits standard drill chucks. The heavy-duty grade cobalt construction handles stainless steel, hardened alloys, cast iron, and other tough materials that standard high-speed steel bits cannot reliably penetrate. The right-hand spiral flute evacuates chips efficiently during drilling operations.

Key Features

• Cobalt construction rated heavy duty for drilling stainless steel and hardened alloys
• TiN coating increases surface hardness and extends cutting life
• 135-degree split point starts on center and reduces thrust force required
• Screw machine (stub) length at 1-11/16 inches OAL provides maximum rigidity and minimal deflection
• Web-thinned parallel web design reduces cutting resistance
• Right-hand spiral flute for efficient chip evacuation
• Straight cylindrical shank fits standard drill chucks without adapters

Compatibility

Designed as a direct-fit stub-length drill bit for standard drill chucks accepting a 0.0781-inch straight cylindrical shank, compatible with hand drills, drill presses, and CNC drilling equipment.

Installation Notes

Install the shank fully into the chuck and tighten securely before use. Ensure the workpiece is clamped or fixtured to prevent movement during drilling. Apply cutting fluid or lubricant when drilling stainless steel or hardened alloys to manage heat buildup and extend bit life. Do not exceed the recommended RPM range for the bit diameter and material being drilled.