Cle-line C30516 Cobalt Mechanics Drill Bit Letter E 1/4 in

Product Description

The CLE-LINE C30516 is a cobalt mechanics drill bit sized at Letter E (1/4 inch, 0.2500 inches decimal), designed for left-hand cutting applications in hard and exotic workpiece materials. Built to ASME B94.11M standards, this bit features a 135-degree split point that self-centers on contact and reduces the thrust force needed to start the hole. The gold-finish cobalt construction handles heat generated when drilling superalloys and titanium, materials that quickly degrade standard high-speed steel tooling. Licensed HVAC, mechanical, and industrial service technicians reach for this bit when removing broken fasteners or drilling into high-strength alloys that demand left-hand cutting geometry.

The C30516 belongs to CLE-LINE Series 1880, a mechanics-length line sized for close-quarter drilling where a jobber-length bit would be impractical. The shorter overall length of 3-5/16 inches (3.3125 inches) gives the bit added rigidity and reduces deflection in interrupted cuts. Its primary application is drilling superalloys, titanium, and other ISO material groups H, K, M, P, and S. The left-hand cutting direction makes this bit a standard choice when the goal is to back out a broken bolt or stud while drilling, allowing the fastener to spin free without additional extraction tools.

Key Features

• 135-degree split point with web thinning for self-centering starts and reduced thrust on hard materials
• Left-hand cutting direction aids broken fastener extraction during drilling
• Cobalt tool material with gold finish resists heat buildup in superalloys and titanium
• Mechanics length (3-5/16 inches OAL) provides added rigidity and suits confined-space drilling
• Straight-cylindrical shank (1/4 inch diameter) fits standard three-jaw drill chucks
• Tapered web configuration with regular spiral fluting clears chips efficiently in deep holes

Compatibility

Designed for use in drilling superalloys and titanium workpieces per ISO material groups H, K, M, P, and S. Fits any standard three-jaw chuck accepting a 1/4-inch straight-cylindrical shank. Meets ASME B94.11M dimensional standards for mechanics-length drill bits.

Installation Notes

Left-hand drill bits require a reversible drill or driver set to reverse rotation before use. Secure the workpiece firmly before drilling to prevent walking on hard materials. Coolant-through is not supported on this bit; apply cutting fluid externally at the drill point when working high-hardness alloys to extend tool life. Replace the bit if the cutting edges show chipping or the split point geometry is worn, as a degraded point increases thrust and heat significantly.