Chicago-latrobe 49424 Screw Machine Drill Bit 0.055 in Hss

Product Description

The CHICAGO-LATROBE 49424 is a screw machine length drill bit designed for high-production drilling in cast iron and steel. Built from heavy-duty high speed steel with a coated finish, it features a 135-degree split point that reduces walking and allows faster penetration without a center punch. The stub-length body provides added rigidity over jobber-length bits, making it well suited for drill press and CNC work where runout and deflection must be minimized. At 0.055 inches in diameter, it corresponds to wire gauge size number 54 and holds a tight diameter tolerance of plus 0.0000 to minus 0.0005 inches.

This bit is used in precision metalworking applications where small-diameter, close-tolerance holes are required. It suits residential shop environments, tool rooms, and light manufacturing floors where technicians drill into cast iron or steel components. The short overall length of 1-5/8 inches and a flute length of 5/8 inch make it appropriate for confined setups and gang-drilling fixtures. The parallel web configuration with web thinning reduces thrust requirements, which matters when running small-diameter bits at high RPM on sensitive materials.

Key Features

• Wire gauge size number 54, 0.055 inch diameter with plus 0.0000 to minus 0.0005 inch tolerance
• 135-degree split point reduces walking and lowers required thrust force
• Heavy-duty high speed steel construction for durability in cast iron and steel
• Screw machine (stub) length at 1-5/8 inches overall for added rigidity
• Web-thinned parallel web reduces heat buildup and improves chip evacuation
• Meets NAS 907 and ISO standards for precision tooling

Compatibility

Designed as an OEM-style replacement or direct-use screw machine drill bit for applications requiring a number 54 wire gauge hole in cast iron or steel workpieces.

Installation Notes

This bit is installed and used by machinists, tool-and-die technicians, and metalworking trades. Secure the straight-cylindrical shank firmly in a drill chuck or collet and verify runout before starting a cut. Use appropriate cutting fluid or coolant for steel applications to extend bit life, noting that this bit does not support coolant-through delivery. Replace the bit at the first sign of chatter, oversize holes, or burning to maintain hole tolerance.