Chicago-latrobe 42791 Letter U Jobber Drill Bit Tialn Hss

Product Description

The CHICAGO-LATROBE 42791 is a jobber-length drill bit in letter size U, manufactured from high speed steel with a TiAlN (titanium aluminum nitride) coating for extended tool life in demanding applications. The 135-degree split point reduces walking and allows drilling to start without a center punch on most surfaces. The bit measures 5 inches overall length with a 3.625-inch flute length, a 0.3680-inch decimal diameter, and a straight-cylindrical shank. It is designed for right-hand, two-flute spiral cutting and carries a web-thinned, tapered web configuration for improved chip evacuation. Series 150ASP-TA is a heavy-duty grade line built to NAS 907 Type B standards and is suited for production and maintenance environments.

The 42791 is engineered for drilling titanium as its primary workpiece material, making it appropriate for aerospace, defense, and precision fabrication shops. The TiAlN coating provides heat resistance at elevated cutting speeds that are common in titanium work. The regular spiral flute geometry and web-thinned point make this bit effective in both CNC machining centers and hand-drill applications where consistent hole size and finish are required. A straight-cylindrical shank at 1.375 inches accommodates standard three-jaw chucks and collet holders. This bit does not support coolant-through delivery.

Key Features

• TiAlN coating extends tool life in high-heat, high-hardness workpiece materials including titanium
• 135-degree split point reduces thrust and eliminates center-punch requirement on most materials
• Web-thinned, tapered web improves chip flow and reduces cutting resistance
• Meets NAS 907 Type B specification for aerospace-grade drilling applications
• Heavy-duty grade high speed steel construction rated for production use
• Regular spiral, two-flute geometry maintains hole straightness in deeper passes

Compatibility

Designed as a NAS 907 Type B compliant jobber-length drill bit for use with standard three-jaw chucks and collet holders accepting straight-cylindrical shanks. Primary workpiece material is titanium; also applicable in ferrous and non-ferrous materials within the 0.3500 to 0.4000 inch diameter range per Series 150ASP-TA specifications.

Installation Notes

Installation and use should be performed by qualified machinists or maintenance technicians familiar with drill press or CNC spindle setup. Secure the shank fully in the chuck or collet and verify runout before cutting. Apply appropriate cutting fluid or coolant externally when drilling titanium, as this bit does not support coolant-through delivery. Inspect the cutting edge and coating condition before each use and remove from service if chipping or wear is detected.