Hertel 4139986 Cobalt Jobber Drill Bit No. 4 Tialn

Product Description

The HERTEL 4139986 is a cobalt steel jobber-length drill bit sized to wire gauge No. 4 (0.2090 inches decimal), designed for heavy-duty holemaking in hard and abrasive materials. The bit carries a TiAlN (titanium aluminum nitride) coating that extends tool life by reducing heat buildup and surface wear at high cutting speeds. A 135-degree split point geometry allows the bit to self-center on the workpiece and reduces the thrust force required to start the cut. The straight-cylindrical shank fits standard three-jaw drill chucks. Overall length is 3.75 inches with a flute length of 2.5 inches. Machinists, maintenance technicians, and trade professionals who drill stainless steel, high-strength alloys, and hardened materials rely on cobalt-grade tooling of this type.

This bit is suited for production drilling and maintenance applications where standard high-speed steel tooling wears too quickly. Typical uses include holemaking in structural steel, stainless fastener clearance holes, heat exchanger tube sheets, and equipment frames. The regular spiral flute promotes chip evacuation in both through-hole and blind-hole work. The web-thinned, tapered-web geometry reduces cutting resistance and improves hole geometry at entry and exit. No coolant-through capability is present, so external flood or mist coolant is recommended when drilling hard alloys at sustained feed rates.

Key Features

• Cobalt steel construction for drilling hardened metals, stainless steel, and high-strength alloys
• TiAlN coating reduces heat buildup and extends cutting edge life
• 135-degree split point self-centers and lowers required thrust force
• Web-thinned tapered web improves chip flow and reduces walking at entry
• Regular spiral flute promotes chip evacuation in through-hole and blind-hole applications
• Straight-cylindrical shank fits standard three-jaw chucks without adapters

Compatibility

Designed as an OEM-style jobber drill for use in any standard drill press, hand drill, or CNC machining center equipped with a three-jaw chuck or collet accepting a 0.2090-inch straight shank.

Installation Notes

Install and remove drill bits only with the machine powered down and the spindle fully stopped. Secure the shank fully within the chuck jaws and confirm runout before beginning a cut. When drilling hard alloys or stainless steel, apply external cutting fluid or mist coolant to manage heat and preserve coating integrity. Follow applicable shop safety standards and machine manufacturer guidelines for speed and feed selection.