Osg 2951400 Spiral Flute Tap 4-40 Unc Vanadium Hss

Product Description

The OSG 2951400 is a spiral flute tap designed for cutting 4-40 UNC internal threads in a single-pass tapping operation. Built from vanadium high-speed steel with a bright uncoated finish, it delivers solid wear resistance for small-diameter threading work. The modified bottoming chamfer allows threading closer to the bottom of a blind hole than a standard plug or taper tap. With a 50-degree helix angle and two flutes, it is optimized for efficient chip evacuation in aluminum and similarly machinable materials. Machinists, tool-and-die technicians, and maintenance trades rely on this geometry for precise, consistent threads in tight-tolerance applications.

The OSG 2951400 is suited for small-fastener thread applications in aluminum and other free-machining materials. The 4-40 UNC thread size is common in instrument panels, electronics enclosures, light mechanical assemblies, and precision fixtures where small-diameter machine screws are standard. The modified bottoming chamfer makes it particularly useful when thread depth close to the hole bottom is required. This tap is intended for use in hand tapping or low-speed machine tapping setups where controlled feed and torque can be maintained.

Key Features

• 4-40 UNC thread form with right-hand thread direction and H3 thread limit for consistent tolerance control
• 50-degree spiral helix angle promotes upward chip evacuation, reducing clogging in blind holes
• Modified bottoming chamfer allows threading to within a few threads of the hole bottom
• Vanadium high-speed steel construction provides increased wear resistance compared to standard HSS
• Bright uncoated finish suitable for use with cutting fluids on aluminum and similar alloys
• Compact 1.875-inch overall length fits standard tap holders and T-handle wrenches

Compatibility

Designed as a direct-fit replacement or standard tooling selection for any application requiring a 4-40 UNC spiral flute tap with an H3 thread limit and modified bottoming chamfer geometry.

Installation Notes

This tap is installed by machinists or maintenance technicians using a T-handle tap wrench or a machine tapping head set to the appropriate low speed and feed for the 4-40 thread size. Always drill the correct tap drill size and clear chips from the hole before tapping. Apply a suitable cutting fluid for the workpiece material to extend tap life and improve thread finish. Do not force the tap if resistance increases suddenly — back off to clear chips before continuing.