Chicago-latrobe 78704 Screw Machine Drill Bit 1/8 in

Product Description

The CHICAGO-LATROBE 78704 is a screw machine length drill bit designed for precision drilling in hard and dense materials. Built from submicron-grade solid carbide, it delivers the rigidity and wear resistance needed when working with cast iron, hardened steel, composites, and other tough substrates. The bit measures 1/8 inch (0.1250 inch) in diameter with a 2-inch overall length and features a 118-degree four-facet point geometry with web thinning for reduced thrust and cleaner entry. The bright, uncoated finish keeps the surface smooth and allows direct inspection of the cutting edges. Machinists, tool and die technicians, and fabrication professionals install this bit in screw machines, CNC drill presses, and benchtop drilling operations.

The 78704 is suited for screw machine and short-run drilling applications where a stubby, rigid tool profile is required to minimize deflection. The 5/8-inch flute length and 2-inch overall length make it well-matched for shallow-to-moderate depth holes in production environments. Its straight-cylindrical shank, also 0.1250 inch in diameter, seats directly in standard drill chucks and collets without adapters. Typical use cases include drilling pilot holes, through-holes, and clearance holes in hard material workpieces on both manual and CNC setups.

Key Features

• Submicron-grade solid carbide construction for maximum hardness and wear resistance in difficult materials
• 118-degree four-facet point with web thinning reduces entry thrust and improves hole accuracy
• Screw machine length profile (2-inch OAL) provides rigidity and minimizes runout during high-speed drilling
• Bright, uncoated finish compatible with a wide range of cutting fluids and dry-cutting applications
• Right-hand cut with regular spiral flutes for efficient chip evacuation in short-hole drilling
• Tight diameter tolerance of +0.0000 to -0.0005 inch meets ISO standards for close-tolerance work

Compatibility

Designed as a general-purpose screw machine length carbide drill bit rated for hard material workpieces; fits any standard drill chuck or collet accepting a 0.1250-inch straight-cylindrical shank.

Installation Notes

Installation is performed by machinists or tool-setup technicians on drill presses, screw machines, or CNC machining centers. Ensure the spindle is fully stopped and the machine is locked out before changing bits. Seat the shank fully in the collet or chuck and verify runout with an indicator before production drilling. Solid carbide bits are brittle compared to high-speed steel; avoid side loading, interrupted cuts without proper feed management, and dropping or striking the cutting edges.