Osg 1726801 Spiral Point Tap 4-40 Unc 2 Flute Plug

Product Description

The OSG 1726801 is a spiral point plug tap designed for cutting 4-40 UNC internal threads in a variety of ferrous materials. Manufactured from vanadium high speed steel (HSS-E) with a steam oxide coating, it offers improved lubricity and corrosion resistance during threading operations. The spiral point geometry pushes chips forward ahead of the cutting action, making it well suited for through-hole tapping where chip evacuation is a priority. With 2 flutes and an H6 thread limit, this tap holds tight tolerance control appropriate for precision threaded assemblies. Overall length is 1.874 inches with a thread length of 0.33 inches and a shank diameter of 0.141 inches.

This tap is intended for threading 4-40 UNC through holes in hardened steel, low-carbon steel, medium-carbon steel, and stainless steel. It is commonly used in light manufacturing, maintenance and repair, and precision assembly applications where small-diameter unified coarse threads are required. The plug chamfer provides a gradual lead-in that distributes cutting load across several threads, reducing the risk of tap breakage in difficult materials. Series 300 designation confirms its place in the OSG standard production tap lineup.

Key Features

• Spiral point geometry pushes chips forward, optimizing performance in through-hole applications
• Vanadium high speed steel (HSS-E) construction for improved wear resistance over standard HSS
• Steam oxide coating provides lubricity and mild corrosion protection during cutting
• H6 thread limit for controlled oversize tolerance in precision threading
• Plug chamfer distributes cutting load gradually, reducing tap breakage risk
• Right-hand thread direction, no coolant-through requirement

Compatibility

Designed for cutting 4-40 UNC right-hand internal threads in hardened steel, low-carbon steel, medium-carbon steel, and stainless steel workpieces. Compatible with standard straight-shank tap holders and tap chucks accepting a 0.141-inch shank diameter.

Installation Notes

Tapping operations should be performed by a machinist or qualified trade professional using a properly aligned tap holder or tapping head to prevent thread misalignment and tap breakage. Always apply cutting fluid appropriate for the workpiece material, particularly when threading stainless steel. Secure the workpiece fully before beginning the threading operation and confirm the drilled hole diameter matches the recommended tap drill size for 4-40 UNC. Inspect the tap for wear or chipping before each use, as small-diameter taps are susceptible to breakage under side load or misalignment.