Precision Twist Drill 5998391 3/8 Inch Hss Jobber Drill Bit

Product Description

The PRECISION TWIST DRILL 5998391 is a jobber-length drill bit designed for general-purpose drilling in metal and alloy workpieces. Built from high-speed steel (HSS) with a bright uncoated finish, this bit features a 118-degree standard point angle and a regular spiral flute geometry that efficiently clears chips during through-hole and blind-hole operations. At 0.375 inches in diameter with a 5-inch overall length and a 3.625-inch flute length, it fits standard drill chucks without adapters. The web-thinned, tapered-web construction reduces entry resistance and extends cutting life across a range of base metals. Licensed HVAC technicians, plumbers, and electricians reach for this bit when drilling access or mounting holes in ferrous and non-ferrous substrates during field installations.

This drill bit is suited for drilling into steel, cast iron, non-ferrous metals, superalloys, and titanium in both shop and field environments. Its straight-cylindrical shank seats securely in standard 3-jaw chucks on corded or cordless drills and drill presses. The 10xD flute-to-diameter ratio provides adequate chip evacuation depth for most trade applications, including panel knockouts, pipe routing holes, bracket mounting, and equipment anchoring. It is a single-piece, individually packaged bit from the R10H-R18H series.

Key Features

• 3/8 inch (0.3750 inch) diameter with matching straight-cylindrical shank for secure chuck engagement
• 118-degree standard point angle with web-thinned, tapered-web construction for reduced drilling force
• High-speed steel construction — suitable for steel, cast iron, non-ferrous metals, superalloys, and titanium
• Regular right-hand spiral flute with 3.625-inch flute length and 10xD flute-by-diameter ratio for efficient chip clearing
• Bright uncoated finish; no coolant-through requirement — compatible with dry drilling or standard cutting fluids
• ANSI-compliant jobber-length geometry; Series R10H-R18H general-purpose classification

Compatibility

Designed as a general-purpose jobber-length drill bit for use in standard 3-jaw drill chucks accepting a 3/8 inch straight-cylindrical shank. Suitable for drilling steel, cast iron, non-ferrous metals, superalloys, and titanium per ANSI specification.

Installation Notes

This bit is installed by a qualified tradesperson using a corded or cordless drill or drill press with a 3-jaw or keyless chuck rated for the shank diameter. Secure the workpiece before drilling and verify chuck tightness to prevent bit slippage. When drilling hard metals such as cast iron or superalloys, use an appropriate cutting fluid and moderate feed pressure to prevent overheating and premature edge wear. Inspect the cutting edges before each use and replace the bit if chipping or dulling is observed.