Osg 2885805 Spiral Point Tap 5/16-18 Unc Tin Hss

Product Description

The OSG 2885805 is a spiral point tap designed to cut right-hand internal threads in through-hole applications. Built from high-speed steel (HSS) with a titanium nitride (TiN) coating, it handles the heat and abrasion generated during tapping while extending tool life compared to uncoated alternatives. The 5/16-18 UNC thread form, 2-flute spiral point geometry, and plug chamfer allow chips to push forward ahead of the cutting action, making this tap well-suited to production environments where through-hole tapping is common. The H3 thread limit and 2B class of fit produce threads within standard tolerance for general mechanical fastening.

This tap is intended for use in ferrous and non-ferrous through-hole applications. Compatible material applications include aluminum, cast aluminum, low-carbon steel, and medium-carbon steel. The plug chamfer style requires a through-hole with clearance on the exit side for chip evacuation. Machinists and maintenance technicians in machine shops, fabrication facilities, and industrial maintenance settings will find this tap appropriate for standard production tapping operations on manual mills, drill presses, and CNC tapping cycles.

Key Features

• Spiral point geometry pushes chips forward for clean through-hole tapping
• TiN coating improves wear resistance and reduces friction against work material
• High-speed steel construction withstands tapping heat in steel and aluminum
• H3 thread limit with 2B class of fit meets standard fastener thread tolerances
• Plug chamfer provides gradual thread engagement suitable for through-holes
• Right-hand thread direction for standard tapping operations

Compatibility

Designed for through-hole tapping of 5/16-18 UNC threads in aluminum, cast aluminum, low-carbon steel, and medium-carbon steel workpieces. Not intended for blind-hole applications where forward chip evacuation is restricted.

Installation Notes

This tap should be installed in a tap holder or collet sized to the 0.318-inch shank diameter. Use appropriate cutting fluid for the work material to reduce heat buildup and extend tool life. Ensure the workpiece is securely fixtured and the hole is drilled to the correct tap drill size for 5/16-18 UNC before beginning the tapping operation. Inspect the tap for wear or chipping before each use and replace it at the first sign of thread-form degradation.