Hertel 04139358 Cobalt Jobber Drill Bit Letter H

Product Description

The HERTEL 04139358 is a cobalt jobber-length drill bit sized to Letter H (0.2660 inches) with a 135-degree split point and oxide finish. Built to heavy-duty grade, it is designed for holemaking in harder steels, stainless alloys, and abrasion-resistant materials where standard high-speed steel bits wear prematurely. The split point geometry reduces walking and requires less feed force at entry. The straight-cylindrical shank seats directly in standard drill chucks without an adapter. This bit is sold individually and is a common choice for machinists, pipefitters, and maintenance mechanics working with tougher base materials.

This jobber drill is suited for general-purpose holemaking in ferrous metals, structural steel, and hard alloys in both shop and field environments. The 4-1/8-inch overall length and 2-7/8-inch flute length fit standard drill presses, hand drills, and magnetic base drills. The regular spiral flute clears chips efficiently in through-hole applications. No coolant-through capability is present, so external coolant or cutting fluid is recommended when drilling at sustained feed rates in production settings.

Key Features

• Letter H size at 0.2660 inches decimal equivalent for precise hole sizing
• 135-degree split point reduces thrust force and prevents tip walking on entry
• Cobalt construction provides heat and wear resistance beyond standard HSS
• Oxide finish adds surface hardness and lubricity during cutting
• Web-thinned tapered web reduces cutting resistance through the full flute length
• Right-hand spiral flute with regular helix for efficient chip evacuation

Compatibility

Designed as a standard jobber-length drill bit for use in any drill press, hand drill, or magnetic base drill accepting a 0.2660-inch straight-cylindrical shank. Fits standard three-jaw drill chucks without modification.

Installation Notes

Secure the shank fully in the drill chuck and verify runout before drilling. Use appropriate cutting fluid or coolant when drilling hard or stainless alloys to extend tool life and prevent work hardening at the cut zone. Follow applicable shop safety and OSHA standards for rotating tool operation. Inspect the cutting edges before each use and do not run a chipped or dull bit, as doing so accelerates wear and can damage the workpiece.