Hertel 66693466 Screw Machine Drill Bit Letter I Tin Hss

Product Description

The HERTEL 66693466 is a screw machine length drill bit designed for high-production drilling in metal fabrication and machining environments. Sized at Letter I (0.2720 inches), it features a 135-degree split point that reduces walking on entry and lowers thrust requirements compared to conventional 118-degree points. The bit is manufactured from high-speed steel with a titanium nitride (TiN) coating that extends tool life by reducing friction and heat buildup at the cutting edge. At 2-11/16 inches overall length, screw machine length geometry provides added rigidity over jobber-length bits, making it well suited to drill press, CNC turret, and screw machine applications where chatter and deflection must be minimized.

This drill bit is used in light to heavy-duty metal cutting operations including ferrous and non-ferrous stock. The straight-cylindrical shank seats securely in standard three-jaw drill chucks and collet-style toolholders without requiring a morse taper adapter. The regular spiral flute geometry and parallel web configuration promote consistent chip evacuation in through-hole and blind-hole drilling. It is installed by machinists, tool and die makers, and maintenance technicians working with manual drill presses, CNC machining centers, and gang-drill setups where a compact, rigid bit profile is preferred over longer jobber-length alternatives.

Key Features

• Letter I size: 0.2720 inches diameter for precise fit in size-toleranced hole applications
• 135-degree split point reduces entry walking and decreases axial thrust load
• TiN coating extends cutting edge life and reduces built-up edge on ferrous materials
• Screw machine length (2-11/16 inches OAL) provides greater rigidity than jobber-length bits
• Web-thinned parallel web design promotes clean chip flow and reduces heat concentration
• Heavy-duty grade construction rated for sustained production drilling cycles

Compatibility

Designed as a direct-fit replacement for Letter I screw machine length drill bits used in standard three-jaw chucks and straight-shank collet toolholders accepting a 0.2720-inch shank diameter.

Installation Notes

Install in a properly sized drill chuck or collet and tighten to the toolholder manufacturer's specified clamping torque range before operation. Ensure the spindle is fully stopped and locked out before changing bits. Use cutting fluid appropriate for the workpiece material to maintain TiN coating integrity and extend service intervals. Inspect the cutting edge for chipping or coating wear before each production run; a damaged split point will increase thrust and reduce hole quality.