Chicago-latrobe 41778 Jobber Drill Bit Letter H Tin Hss

Product Description

The CHICAGO-LATROBE 41778 is a jobber-length drill bit sized at Letter H (0.2660 inches decimal) with a 135-degree split point and a titanium nitride (TiN) coating over a high-speed steel body. The split point geometry reduces walking on entry and lowers thrust requirements, while the TiN coating extends edge life when drilling abrasive materials. Overall length is 4-1/8 inches with a 2-7/8-inch spiral flute. This is a heavy-duty, high-performance bit from the 150ASP-TN series, meeting NAS 907 Type B standards. It is installed and used by machinists, maintenance mechanics, pipefitters, and fabricators working in metal fabrication and industrial maintenance environments.

The 41778 is engineered for drilling cast iron, stainless steel, and carbon steel. The regular spiral flute with a tapered, web-thinned web configuration improves chip evacuation and reduces heat buildup in tougher alloys. The straight-cylindrical shank measures 1.2500 inches in diameter and 1.2500 inches in length (31.75 mm), fitting standard drill chucks and collet holders without modification. This bit is well suited for production drilling, maintenance repair operations, and toolroom work where hole location accuracy and edge longevity matter.

Key Features

• Letter H size: 0.2660 inches decimal diameter, tolerance -0.0010 to 0.0000 inches
• 135-degree split point reduces walk and lowers feed pressure on entry
• Titanium nitride (TiN) coating increases surface hardness and extends cutting life
• Web-thinned, tapered web configuration improves chip flow and reduces heat
• Right-hand cut, regular spiral, 2-flute design for general-purpose metal drilling
• Meets NAS 907 Type B specification for heavy-duty, high-performance tooling

Compatibility

Designed for use in standard drill chucks and collet holders accepting a 1.2500-inch straight-cylindrical shank. Primary workpiece materials are cast iron, stainless steel, and steel as stated in the product specification.

Installation Notes

Install this bit in a drill press, hand drill, or milling machine chuck and tighten securely before operation. Ensure the workpiece is clamped or fixtured to prevent movement during drilling. Use cutting fluid or coolant appropriate to the workpiece material to manage heat, particularly when drilling stainless steel. Inspect the cutting edges before each use and replace the bit if chipping or excessive wear is present to maintain hole tolerance.