Chicago-latrobe 70308 Drill Bit Letter H 0.2660 in Hss Tin

Product Description

The CHICAGO-LATROBE 70308 is a jobber-length twist drill bit sized to letter H, equivalent to 0.2660 inches in decimal. Built from high speed steel with a titanium nitride (TiN) coating, it delivers added surface hardness and extended tool life compared to uncoated HSS. The bit features a 118-degree standard point angle, a two-flute regular spiral configuration, and a web-thinned, tapered web for reduced thrust during entry. Overall length is 4.125 inches with a flute length of 2.875 inches. The straight-cylindrical shank measures 0.2660 inches in diameter. This is a general-purpose drill intended for machinists, maintenance technicians, and metalworking tradespeople.

The 70308 is rated for drilling cast iron and steel in general-purpose applications. Its jobber-length geometry suits bench drill presses, knee mills, and hand-held power drills where standard reach is sufficient. The right-hand spiral flute evacuates chips efficiently in both ferrous and light-alloy materials. It conforms to DIN 338 standards, making it a common replacement or stock bit for job shops, HVAC fabrication, plumbing rough-in, and electrical panel work where precise hole sizing by letter designation is required.

Key Features

• Letter H size — 0.2660 inches decimal equivalent with a diameter tolerance of -0.0010 to 0.0000 inches
• Titanium nitride (TiN) coating increases surface hardness and reduces friction at the cutting edge
• 118-degree standard point angle with web thinning reduces drill thrust and improves centering
• Two-flute regular spiral design promotes chip clearance in steel and cast iron
• Straight-cylindrical shank fits standard drill chucks without adapter
• Conforms to DIN 338 jobber-length standard for consistent dimensional performance

Compatibility

Designed as a general-purpose jobber-length drill bit for use in steel and cast iron workpieces. Fits any standard drill chuck accepting a 0.2660-inch straight-cylindrical shank.

Installation Notes

Install in a drill press, milling machine, or hand drill with a chuck rated for the shank diameter. Secure the workpiece firmly before drilling to prevent movement and bit breakage. Use cutting fluid or coolant when drilling steel to manage heat buildup, as TiN-coated HSS bits are not designed for dry high-speed runs in hard ferrous materials. Inspect the cutting edge before each use and replace if chipping or excessive wear is present.