Precision Twist Drill 5997608 Drill Bit Letter E 1/4 in

Product Description

The PRECISION TWIST DRILL 5997608 is a jobber-length drill bit sized to Letter E, equivalent to 0.2500 inches in diameter, designed for general-purpose drilling in metalworking applications. Ground from high-speed steel with a steam oxide coating, the bit features a 135-degree split-point tip for reduced walking and faster penetration on hard surfaces. The overall length is 4 inches with a 2.75-inch spiral flute and a straight cylindrical shank. It is web-thinned with a tapered web configuration, reducing thrust requirements during drilling. This bit is used by machinists, maintenance mechanics, and trade professionals working with metal fabrication and repair tasks.

The 5997608 is suited for drilling into steel, stainless steel, cast iron, non-ferrous metals, superalloys, and titanium. The regular spiral flute with right-hand cut geometry handles a broad range of metalworking scenarios, including production drilling and field repair work. With a flute-to-diameter ratio of 11xD and a 2.75-inch maximum drilling depth, it is appropriate for through-hole and blind-hole operations in material thicknesses up to the rated flute length. This is a single-piece, individual-quantity bit commonly kept in trade tool kits and service vans.

Key Features

• Letter E size — 0.2500 inches diameter — matches standard tap and clearance drill charts for 1/4-inch fastener work
• 135-degree split-point tip reduces bit walking on flat or curved metal surfaces without a center punch
• Steam oxide coating provides light lubricity and corrosion resistance during storage and use
• Web-thinned tapered web lowers drilling thrust and extends bit life in harder alloys
• Right-hand cut, regular spiral flute with 2-flute geometry for efficient chip evacuation
• Meets ANSI and NAS 907 standards; rated for steel, stainless steel, cast iron, non-ferrous metals, superalloys, and titanium

Compatibility

Designed as a general-purpose jobber-length drill bit for use in standard 3-jaw drill chucks, drill presses, and hand drills accepting a 0.2500-inch straight cylindrical shank. Compatible with applications calling for Letter E or 1/4-inch drill bit sizing per ANSI and NAS 907 standards.

Installation Notes

Secure the straight cylindrical shank fully in the chuck before operation and verify the chuck is tightened with the key before starting the drill. Use appropriate cutting fluid or coolant when drilling stainless steel, superalloys, or titanium to prevent work hardening and premature tip wear. Do not exceed the rated 2.75-inch flute depth in a single pass on deep holes — peck drilling in stages improves chip clearance and reduces heat buildup. Follow applicable shop safety standards and wear eye protection when drilling metal.