Osg 2916601 Spiral Flute Tap 4-40 Unc Modified Bottoming

Product Description

The OSG 2916601 is a spiral flute tap designed for cutting 4-40 UNC internal threads in a wide range of ferrous metals. Built from 3% vanadium high-speed steel (HSS) and finished with a steam oxide coating, this tap delivers consistent thread quality while resisting wear and heat buildup during cutting. The modified bottoming chamfer allows threading close to the bottom of blind holes. With a 45-degree helix angle and 3 right-hand flutes, it efficiently evacuates chips upward out of the hole, reducing the risk of tap breakage in interrupted or deep cuts. At 1.875 inches overall length, it fits standard tap holders and CNC tooling setups.

This tap is suited for threading operations in alloy steel, carbon steel, cast iron, stainless steel, die steel, and hardened steel. It is a common choice for precision work in machine shops, maintenance environments, and production lines where consistent 4-40 UNC thread form and close-tolerance fit are required. Thread limit H5 positions this tap for applications where a controlled thread fit is specified by engineering or print requirements.

Key Features

• 4-40 UNC thread form with right-hand thread direction
• 45-degree spiral flute helix for efficient upward chip evacuation in blind holes
• Modified bottoming chamfer for threading near the bottom of blind holes
• 3% vanadium HSS construction for improved wear resistance over standard M2 HSS
• Steam oxide coating reduces friction and provides corrosion resistance
• H5 thread limit for controlled-fit threading applications

Compatibility

Designed as a direct-fit replacement tap for standard 4-40 UNC threading applications in machine shops and production environments where spiral flute taps with modified bottoming chamfer geometry are specified.

Installation Notes

Installation should be performed by a machinist or qualified technician using a calibrated tap holder or CNC rigid tapping setup. Ensure the workpiece is securely fixtured and the pilot hole diameter matches the recommended tap drill size for 4-40 UNC before beginning. Apply appropriate cutting fluid for the workpiece material, particularly when tapping stainless or hardened steel. Do not use this tap in a hand-held drill or without proper alignment, as misalignment will cause tap breakage or off-spec threads.