Osg 1230408 Spiral Point Tap 1/4-28 Unf Ticn Hss

Product Description

The OSG 1230408 is a spiral point tap designed for threading 1/4-28 UNF 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 increased surface hardness and reduced friction compared to uncoated tooling. The plug chamfer geometry guides thread initiation smoothly, while the 2-flute spiral point design pushes chips ahead of the tap and out of the hole, making it well suited for through-hole tapping operations. Overall length is 2.5 inches with a thread length of 0.638 inches and a shank diameter of 0.255 inches.

This tap is intended for use in through-hole applications across a broad material range including aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, high-carbon steel, and hardened steel. It is appropriate for both manual and machine tapping setups in job shop, production, and maintenance environments. The 3B class of fit and H3 thread limit make it suitable for standard-tolerance threaded assemblies requiring a free-fitting mating thread. Machinists and toolroom professionals are the primary users of this tap.

Key Features

• 1/4-28 UNF thread size with H3 thread limit and 3B class of fit for standard free-fit assemblies
• TiCN coating increases surface hardness and lubricity, extending tool life in steel and cast iron
• 2-flute spiral point geometry pushes chips forward through the hole, reducing re-cutting and tap breakage
• Plug chamfer for straightforward thread entry and consistent start in through-hole applications
• Right-hand thread direction compatible with standard tapping setups and tapping arms
• High-speed steel construction provides toughness and regrindability

Compatibility

Designed as an OEM-style replacement or direct-use spiral point tap for 1/4-28 UNF through-hole tapping operations; compatible with standard 0.255-inch round shank tap holders and quick-change tapping chucks sized for 1/4-inch taps.

Installation Notes

This tap should be installed by a qualified machinist using a properly aligned tap holder or tapping head to prevent off-axis loading and tap breakage. Ensure the workpiece is securely fixtured and that the spindle or tapping arm is set for right-hand rotation before engaging. Apply appropriate cutting fluid for the material being tapped; TiCN-coated taps perform best with light oil or water-soluble coolant rather than dry cutting. Do not reverse the tap under power until threads are fully formed to depth.