Hertel 04138681 Cobalt Jobber Drill No. 21 135 Deg

Product Description

The HERTEL 04138681 is a cobalt jobber-length drill bit sized to wire gauge No. 21, with a decimal equivalent of 0.1590 inches. It features a 135-degree split point with web thinning for fast, accurate starting without a center punch. The oxide and TiN coating provides surface hardness and helps resist heat buildup during drilling. At 3.25 inches overall length with a 2.125-inch flute, this is a standard jobber geometry suited for production and maintenance drilling in hard or abrasive materials. It is installed and used by machinists, maintenance technicians, pipefitters, and HVAC or electrical tradespeople working with metal fabrication or equipment repair.

This drill bit is designed for holemaking in ferrous and non-ferrous metals, stainless steel, cast iron, and other hard materials where standard HSS bits wear prematurely. The cobalt construction handles elevated cutting temperatures, making it appropriate for hand-drill, drill press, and CNC applications in both shop and field environments. The straight cylindrical shank fits standard three-jaw chucks across a wide range of drilling equipment. It is a heavy-duty grade bit suited for repetitive-use applications where bit longevity matters.

Key Features

• Cobalt construction for high heat resistance and extended tool life in hard materials
• 135-degree split point with web thinning for self-centering starts and reduced thrust force
• Oxide and TiN dual coating for added surface hardness and heat management
• Tapered web configuration with regular spiral flute for efficient chip evacuation
• Straight cylindrical shank fits standard drill chucks without adapters
• Heavy-duty grade rated for production and repetitive drilling cycles

Compatibility

Designed as a standard jobber-series replacement drill bit for use in any three-jaw chuck or collet system accepting a 0.1590-inch straight cylindrical shank, within the 0.1500 to 0.2000 inch drill bit size range.

Installation Notes

Secure the shank fully in the chuck before drilling and verify chuck runout is within acceptable limits to avoid premature bit wear. Cobalt bits perform best at lower RPM with consistent feed pressure compared to HSS bits in the same material. Eye protection and appropriate work-holding are required. Do not use this bit for drilling masonry, concrete, or wood composite materials.