Mountain 5/16" Left Hand Stub Drill Bit - Mountain

The Mountain 55679 5/16" Left Hand Stub Drill Bit is engineered for professional mechanics and industrial technicians facing challenges with broken or seized fasteners. Its robust cobalt steel construction and unique left-hand rotation are designed for efficient extraction, significantly streamlining the removal of damaged bolts, screws, and studs in demanding repair environments.

Key Features

• Premium Cobalt Steel Construction: Manufactured from high-grade cobalt steel, this drill bit provides exceptional strength and superior heat resistance, ensuring extended service life when drilling into challenging materials such as stainless steel and cast iron.
• Left-Handed Flute Design: Featuring a counter-clockwise cutting action, this design actively works to back out broken fasteners as drilling progresses, frequently eliminating the need for separate extraction tools.
• 143-Degree Split Point Tip: The self-centering 143-degree split point enables precise and quick starts without walking, reducing the necessity for pilot holes and minimizing required feed pressure for efficient operation.
• "Stubby" Mechanics Length: Designed with a shorter overall length, this "stubby" profile delivers enhanced rigidity and strength, substantially reducing the risk of breakage during heavy-duty and high-stress applications.

Applications

This Mountain 5/16" Left Hand Stub Drill Bit is indispensable for automotive repair, industrial maintenance, and metalworking tasks focused on damaged fastener removal. It excels in scenarios such as extracting broken bolts from engine blocks, removing stripped screws from machinery, or dislodging snapped studs from various components. It also serves to prepare precise pilot holes for subsequent use with screw extractors when encountering particularly stubborn or deeply embedded fasteners.

Specifications

• Manufacturer: Mountain
• Model Number: 55679
• Drill Bit Diameter: 5/16"
• Material: Premium Cobalt Steel
• Point Angle: 143-degree Split Point
• Flute Length: 2-1/8"
• Rotation: Left Hand (Counter-Clockwise)