Osg 2885801 Spiral Point Tap 5/16-18 Unc 2 Flute

Product Description

The OSG 2885801 is a spiral point plug tap designed for cutting 5/16-18 UNC internal threads in through-hole applications. Built from high-speed steel with a steam oxide coating, it delivers solid wear resistance in general-purpose tapping operations. The spiral point geometry pushes chips forward ahead of the tap rather than packing them in the flutes, making it well suited for through-hole work where chip evacuation matters. With 2 flutes, an H3 thread limit, and a 2B class of fit, this tap produces threads within standard commercial tolerances. Overall length is 2.719 inches with a thread length of 0.72 inches (listed as 1-1/8 inches in fractional form) and a shank diameter of 0.318 inches. Right-hand cut. No coolant-through feature.

This tap is intended for use in aluminum, cast aluminum, low-carbon steel, and medium-carbon steel. It fits production and maintenance threading operations in machine shops, manufacturing facilities, and field service environments. The plug chamfer style requires a pre-drilled through hole and is not designed for blind-hole threading. Machinists, tool-and-die tradespeople, and maintenance mechanics are the typical users for this size and style.

Key Features

• Spiral point geometry pushes chips forward for efficient through-hole tapping
• High-speed steel construction handles aluminum and low-to-medium carbon steel
• Steam oxide coating reduces friction and improves lubrication retention
• H3 thread limit with 2B class of fit for standard commercial thread tolerance
• Plug chamfer for use in through-hole applications
• Right-hand thread direction, no coolant-through required

Compatibility

Designed for through-hole tapping in aluminum, cast aluminum, low-carbon steel, and medium-carbon steel workpieces. Cuts 5/16-18 UNC threads to a 2B class of fit.

Installation Notes

Install in a tapping head, CNC machining center, or hand tap wrench sized for the shank diameter. Ensure the workpiece is secured and the pilot hole is drilled to the correct tap drill size for 5/16-18 UNC before starting. Apply a suitable cutting fluid appropriate for the workpiece material to extend tap life and improve thread finish. Do not use this plug-style tap in blind holes where chip packing could cause tap breakage.