Hertel 42247 Cobalt Screw Machine Drill Bit 21/32 in

Product Description

The HERTEL 42247 is a screw machine length cobalt drill bit designed for drilling into tough, heat-resistant materials in production and maintenance environments. Built from M35 cobalt high-speed steel with an oxide straw finish, it delivers heat resistance and edge retention that standard HSS bits cannot match. The 135-degree split point reduces thrust force and self-centers on contact, minimizing the need for a center punch. At 4.5 inches overall length with a 2.875-inch flute length, the stub-length body provides rigidity for accurate, chatter-free holes. Licensed HVAC techs, machinists, pipefitters, and maintenance mechanics typically reach for this bit when working hardened or alloyed materials.

This drill bit is suited for drilling hardened materials, heat-treatable alloyed steels, stainless steel, and titanium alloy. Its shortened screw machine length profile makes it a common choice for drill press work, CNC turret drilling, and hand-held operations where overhang must be minimized. The 3xD flute-to-diameter ratio supports chip evacuation in deep-entry applications on these demanding workpiece materials.

Key Features

• M35 cobalt construction for heat resistance and extended tool life in hard materials
• 135-degree split point for self-centering and reduced feed pressure
• Oxide straw finish improves lubricity and surface hardness
• Screw machine (stub) length provides rigidity and reduces deflection
• Regular spiral flute geometry promotes efficient chip evacuation
• No coolant-through design — compatible with standard flood or manual lubrication

Compatibility

Designed as an OEM-style replacement or direct-use cobalt drill bit for production drilling operations in hardened materials, heat-treatable alloyed steels, stainless steel, and titanium alloy applications.

Installation Notes

This bit is installed in standard drill chucks or collet holders sized for 21/32-inch shanks. Always secure the workpiece before drilling and use appropriate cutting fluid when working stainless steel or titanium alloy to manage heat buildup. Inspect the cutting edges before each use — cobalt bits can micro-chip if run at incorrect feeds and speeds for the workpiece material. Follow applicable OSHA machine guarding requirements when operating drill presses or CNC turret equipment.