Osg 1121308 Straight Flute Tap 3/8-16 Unc Ticn Hss

Product Description

The OSG 1121308 is a straight flute tap designed to cut 3/8-16 UNC internal threads in a wide range of ferrous and non-ferrous materials. Built from high-speed steel (HSS) with a titanium carbonitride (TiCN) coating, it delivers improved wear resistance and longer tool life compared to uncoated alternatives. The plug chamfer configuration provides a gradual lead-in with approximately 3 to 5 chamfered threads, making it suitable for through-hole tapping applications. With an overall length of 2-15/16 inches and a thread length of 1-1/4 inches, this tap fits standard tap holders and machine spindles used in production and maintenance environments. Machinists, tool-and-die makers, and maintenance technicians are the primary users.

This tap is suited for tapping through holes in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. It performs well in both manual hand-tapping operations and light-duty machine tapping on drill presses, CNC machining centers, and tapping machines. The 3B class of fit produces a standard tolerance internal thread appropriate for most commercial fastener applications. The H3 thread limit designation indicates a controlled oversize tolerance to account for material spring-back, which is especially relevant when tapping tougher steels.

Key Features

• TiCN coating increases surface hardness and reduces friction for extended tool life in ferrous and non-ferrous materials
• Plug chamfer (3 to 5 threads) designed for through-hole tapping applications
• H3 thread limit controls tolerance for consistent 3B class of fit results
• 4 straight flutes provide chip clearance suitable for short-chipping materials such as cast iron and aluminum
• Right-hand thread direction, compatible with standard right-hand tap holders and machines
• No coolant-through design keeps construction simple for general-purpose use

Compatibility

Designed for use in standard tap holders accepting a 0.381-inch shank diameter. Compatible with material applications including aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel as specified by the manufacturer.

Installation Notes

Always secure the workpiece before tapping and ensure proper alignment between the tap and the pre-drilled hole to prevent tap breakage. Use an appropriate cutting fluid or tapping compound for the material being threaded, particularly with steels. For machine tapping, verify spindle speed and feed rate are appropriate for the material and tap size before operation. Inspect the tap for wear or chipping before each use and replace when thread quality degrades.