Hertel 66693615 Letter X Screw Machine Drill Bit Hss Tin

Product Description

The HERTEL 66693615 is a screw machine length drill bit sized at Letter X (0.3970 inches decimal) with a 135-degree split point and a titanium nitride (TiN) coating over a high-speed steel (HSS) body. The shorter-than-jobber overall length of 3-5/16 inches provides added rigidity in screw machine and drill press applications, reducing deflection and improving hole accuracy. The web-thinned, split point geometry starts on contact without a center punch, and the TiN coating extends cutting edge life in ferrous and non-ferrous materials. This is a heavy-duty grade bit intended for production and repetitive drilling work by machinists and maintenance technicians.

This drill bit is suited for use in screw machines, CNC turret lathes, drill presses, and similar fixed-spindle equipment where a stubby, rigid cutting tool is preferred over standard jobber length. The 0.3970-inch diameter falls within the 0.3500 to 0.4000 inch size range category. It is appropriate for drilling steel, cast iron, aluminum, and similar materials in light manufacturing, tool-and-die, and industrial maintenance environments. No coolant-through capability is present, so external cutting fluid application is the appropriate approach for extended production runs.

Key Features

• Letter X size: 0.3970 inches decimal diameter for direct substitution in letter-size drill charts
• 135-degree split point with web thinning starts on contact and self-centers without a punch
• TiN coating increases surface hardness and reduces built-up edge in ferrous materials
• Screw machine (stub) length at 3-5/16 inches overall provides rigidity and minimizes runout
• Regular spiral, 2-flute design with 1-15/16 inch flute length clears chips efficiently
• Straight cylindrical shank at 0.3970 inches fits standard drill chucks and collet systems

Compatibility

Designed as an OEM-style replacement or direct substitute for screw machine length drill bits in the Letter X size class; fits any standard drill chuck or collet accepting a 0.3970-inch straight shank.

Installation Notes

Installation is performed by machinists or maintenance technicians using a properly rated drill press, turret lathe, or CNC machine spindle. Secure the straight shank fully in the chuck or collet before operation and verify runout before committing to production work. Apply an appropriate cutting fluid externally since this bit has no coolant-through provision; dry running in steel will shorten coating life and edge retention. Inspect the cutting edges and web condition regularly during high-cycle production use.