Osg 1430308 Spiral Flute Tap 1/4-28 Unf Bottoming Hss Ticn

Product Description

The OSG 1430308 is a spiral flute bottoming tap designed for cutting internal threads in a wide range of metallic workpieces. Built from high-speed steel with a titanium carbonitride (TiCN) coating, it produces 1/4-28 UNF right-hand threads to a 3B class of fit with an H3 thread limit. The spiral flute geometry at a 50-degree helix angle pulls chips up and out of the hole, making it well suited for through and blind-hole applications where chip evacuation is critical. At 2.5 inches overall length, this tap is sized for standard machine tapping operations in production and maintenance environments. Machinists, toolmakers, and maintenance technicians are the primary users.

This tap is intended for use on aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel. The bottoming chamfer allows threading close to the bottom of a blind hole, which is a common requirement in precision machined components and repair work. It is used in CNC machining centers, drill presses, and manual tapping applications where a 1/4-28 UNF thread form is specified. The TiCN coating extends tool life by reducing heat buildup and wear at the cutting edge, making it practical for moderate-to-high volume production runs.

Key Features

• Bottoming chamfer for threading to the bottom of blind holes
• 50-degree right-hand spiral flute for efficient chip evacuation
• TiCN coating reduces friction and extends cutting life across ferrous and non-ferrous materials
• H3 thread limit holds 3B class of fit tolerances consistently
• High-speed steel construction handles interrupted cuts and varying feed rates
• No coolant-through requirement simplifies setup in standard machine environments

Compatibility

Designed for producing 1/4-28 UNF internal threads in aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel workpieces. Part of OSG Series 107.

Installation Notes

Install in a tap holder with appropriate torque control to avoid overloading the tool in blind holes. Power down and lock out any machine spindle before changing or inspecting taps. Use cutting fluid appropriate to the workpiece material to maximize tool life; although no coolant-through channel is present, external flood or mist coolant is recommended for steel applications. Confirm tap drill size matches the 1/4-28 UNF specification before threading to maintain 3B fit tolerances.