Chicago-latrobe 47491 Drill Bit Letter E 1/4 in 118 Hss

Product Description

The CHICAGO-LATROBE 47491 is a jobber-length drill bit sized at Letter E (0.2500 inches / 1/4 inches) with a 118-degree standard point angle. Built from high speed steel (HSS) with an oxide coating, it delivers consistent performance in general-purpose drilling applications. The spiral flute geometry and web-thinned, tapered web configuration promote efficient chip evacuation and reduce thrust during penetration. The tanged, 1/4-inch diameter shank provides positive drive engagement. Overall length is 4 inches with a flute length of 2-3/4 inches. This bit is designed for right-hand cutting and is suited for production or maintenance drilling tasks performed by machinists, maintenance mechanics, and general tradespeople.

The 47491 fits general-purpose drilling in cast iron and steel workpieces, making it applicable across HVAC fabrication, mechanical contracting, plumbing rough-in, and light industrial maintenance environments. It is part of the CHICAGO-LATROBE Series 250AN jobber-length line. With two flutes and a regular spiral type, it performs well in both hand-fed drill press and portable drill operations. The oxide finish provides mild lubricity and corrosion resistance during storage and use.

Key Features

• Letter E (0.2500 inches) diameter with diameter tolerance of -0.0007 to 0.0000 inches for consistent hole sizing
• 118-degree standard point angle for general-purpose entry into cast iron and steel
• High speed steel construction with oxide coating for wear resistance and lubricity
• Web-thinned, tapered web reduces thrust and improves chip flow
• Right-hand, two-flute spiral design for efficient swarf evacuation
• Tanged 1/4-inch shank for positive chuck engagement and drive retention

Compatibility

Designed as a general-purpose jobber-length drill bit suitable for use in standard 3-jaw keyed or keyless chucks accepting a 1/4-inch shank diameter. Primary workpiece materials are cast iron and steel per Series 250AN specifications.

Installation Notes

Install this bit in a properly rated drill press or portable drill with a chuck rated for a 1/4-inch shank before applying power. Secure the workpiece firmly before drilling to prevent movement and ensure accurate hole placement. Use appropriate cutting fluid or lubricant when drilling steel to extend bit life and maintain dimensional accuracy. Inspect the cutting edges for wear or chipping before each use and replace if the point is damaged.