Chicago-latrobe 49091 Screw Machine Drill Bit 0.159 in Lh Hss

Product Description

The CHICAGO-LATROBE 49091 is a screw machine length drill bit designed for general-purpose drilling in production and short-hole applications. Built from high speed steel (HSS) with a bright, uncoated finish, this bit features a left-hand cutting direction and a standard 118-degree point angle. The straight-cylindrical shank seats reliably in standard chucks. At 2.125 inches overall length with a 1.0625-inch flute length, the stub-length body provides added rigidity and reduced deflection compared to jobber-length bits. Web-thinned geometry reduces thrust on entry. Licensed trades and machining professionals working with non-ferrous metals, thermoplastics, and soft materials will find this a dependable stock bit.

The 49091 is suited for drilling aluminum, copper, magnesium, thermoplastic, wood, and slate. The screw machine length profile makes it a practical choice for drill press work, turret lathes, and CNC applications where stub-length tooling is preferred for rigidity. The left-hand cut is particularly useful when drilling out broken right-hand fasteners, as the cutting action applies a counterclockwise torque that can back the fastener out while drilling. Diameter tolerance is held to +0.0000 to -0.0007 inches for consistent hole sizing.

Key Features

• Left-hand spiral flute cuts counterclockwise, useful for removing broken right-hand fasteners
• High speed steel construction with bright, uncoated finish for general-purpose durability
• 118-degree standard point angle with web-thinned, parallel-web geometry for reduced entry thrust
• Screw machine (stub) length body increases rigidity and minimizes deflection in short-hole drilling
• Straight-cylindrical shank fits standard 3-jaw chucks and collet holders
• Meets ISO standards; diameter tolerance +0.0000 to -0.0007 inches

Compatibility

Designed as a general-purpose screw machine length drill bit rated for use in aluminum, copper, magnesium, slate, thermoplastic, and wood workpiece materials, as noted in the Series 157L product specifications.

Installation Notes

Install in a properly sized chuck or collet that matches the straight-cylindrical shank diameter; confirm shank is fully seated and chuck is tightened before operation. Left-hand bits require a reverse-rotation spindle to cut; verify spindle direction before use to avoid workpiece damage. Secure the workpiece with appropriate fixturing before drilling to prevent movement. Follow applicable shop safety standards and machine manufacturer guidelines for speed and feed selection based on workpiece material.