Hertel 42189 Screw Machine Drill Bit 7/32 Cobalt M35

Product Description

The HERTEL 42189 is a screw machine length cobalt drill bit designed for drilling into hard and tough materials in high-demand shop and field applications. Built from M35 cobalt high-speed steel, this bit delivers the heat resistance needed to cut through stainless steel, titanium alloy, heat-treatable alloyed steels, and hardened materials without premature edge failure. At 0.2188 inches (7/32 inch) in diameter and 2.375 inches overall length, it fits standard drill chucks and magnetic-base drills. The 135-degree split point self-centers on contact, reducing the need for a center punch and minimizing walking on hard surfaces. An oxide straw finish provides added lubricity and corrosion resistance during cutting operations.

This drill bit is suited for metalworking professionals, maintenance machinists, pipefitters, and fabricators who regularly work with difficult-to-machine alloys. The screw machine length — shorter than jobber length — provides increased rigidity and reduced deflection, making it a reliable choice for production drilling, repair work, and close-quarter applications where control and accuracy matter. It is appropriate for use in drill presses, CNC machines, hand drills, and magnetic-base drill setups where a compact, stiff bit profile is preferred over a longer jobber-style bit.

Key Features

• M35 cobalt construction retains hardness at elevated cutting temperatures
• 135-degree split point self-centers and reduces thrust force on entry
• Screw machine length body (2.375 inches overall) increases rigidity and reduces deflection
• Oxide straw finish enhances lubricity and provides light corrosion protection
• Regular spiral flute with 1.25-inch flute length promotes efficient chip evacuation
• No coolant-through design — suitable for dry cutting or external coolant application

Compatibility

Designed for drilling hardened materials, heat-treatable alloyed steels, stainless steel, and titanium alloy. Fits any standard drill chuck accepting 7/32 inch round-shank bits. Appropriate for drill presses, hand drills, and CNC equipment within the 0.2000 to 0.2500 inch diameter range class.

Installation Notes

Installation and use of this drill bit should be performed by qualified machinists or trade professionals familiar with proper cutting speeds and feeds for cobalt tooling in hard materials. Secure the workpiece firmly before drilling to prevent movement and bit breakage. Always wear appropriate eye protection and ensure the drill chuck is properly tightened before operation. When cutting stainless steel or titanium, use a cutting fluid or coolant applied externally to extend tool life and improve cut quality.