Precision Twist Drill 5998782 Jobber Drill Bit Letter L

Product Description

The PRECISION TWIST DRILL 5998782 is a jobber-length drill bit sized to Letter L (0.290 inches) and designed for general-purpose drilling in metalworking applications. Ground from high speed steel with a steam oxide coating, this bit runs a 135-degree split-point tip that reduces walking on entry and lowers thrust requirements compared to a standard 118-degree point. The two-flute spiral design with a tapered web and web-thinned tip moves chips efficiently and maintains rigidity over the 4.25-inch overall length. Licensed HVAC technicians, machinists, pipefitters, and maintenance mechanics reach for jobber bits like this one when drilling through steel structural members, enclosures, brackets, and similar ferrous components.

This bit is rated for use on steel, stainless steel, cast iron, non-ferrous metals, superalloys, and titanium, covering ISO material codes P, M, K, N, and S. The straight-cylindrical shank at 0.290 inches diameter fits standard three-jaw drill chucks and compatible quick-change systems without adapters. With a flute-to-diameter ratio of 10xD and a maximum drilling depth of 2.9375 inches, it handles through-hole drilling in typical sheet metal, plate stock, and structural tubing found in HVAC fabrication, plumbing rough-in, and electrical panel work. The R10B-R15B-R18B series designation places it in a heavy-duty jobber line built to NAS 907 and ANSI standards.

Key Features

• Letter L size: 0.290 inches decimal diameter for precise sizing
• 135-degree split-point tip reduces walking and lowers entry thrust
• Steam oxide coating provides light lubricity and corrosion resistance during storage
• Web-thinned, tapered web improves chip evacuation and reduces heat buildup
• Two-flute spiral design rated for steel, stainless steel, cast iron, non-ferrous metals, superalloys, and titanium
• Meets NAS 907 and ANSI standards; heavy-duty grade classification

Compatibility

Designed as a general-purpose jobber-length drill bit compatible with any standard three-jaw drill chuck or keyed chuck accepting a 0.290-inch straight-cylindrical shank, including benchtop drill presses, handheld power drills, and magnetic base drills commonly used in trade applications.

Installation Notes

A licensed machinist, pipefitter, or qualified tradesperson should select the appropriate cutting speed and feed rate for the workpiece material before use. Secure the workpiece firmly before drilling and confirm the chuck is properly tightened to prevent bit slippage. Apply cutting fluid when drilling stainless steel, superalloys, or titanium to reduce heat and extend bit life. Inspect the cutting edges for wear or chipping before each use and remove the bit from service if the point is damaged.