Osg 2942701 Spiral Flute Tap 1/2-13 Unc 3 Flute

Product Description

The OSG 2942701 is a spiral flute tap designed for cutting 1/2-13 UNC internal threads in a wide range of metals. It features a modified bottoming chamfer, which allows threading closer to the bottom of a blind hole than a standard plug or taper tap. The 45-degree helix angle drives chips up and out of the flute during cutting, reducing the risk of chip packing in interrupted or deep cuts. Made from vanadium high-speed steel with a steam oxide finish, this tap offers good lubricity and wear resistance across demanding tapping applications. It carries an H11 thread limit designation, indicating controlled oversize tolerance for use with standard UNC fits.

This tap is suited for production and maintenance threading operations in alloy steel, carbon steel, cast iron, stainless steel, die steel, and hardened steel. The modified bottoming chamfer makes it the right choice when full thread depth near a blind hole bottom is required. With a right-hand flute direction and right-hand thread, it is driven by standard tapping equipment. The 3-3/8 inch overall length fits most standard tap holders and CNC tapping heads used in machining and fabrication shops.

Key Features

• 1/2-13 UNC thread form, right-hand thread direction
• Modified bottoming chamfer for threading close to the bottom of blind holes
• 45-degree helix angle evacuates chips upward, reducing chip packing
• Vanadium high-speed steel construction for toughness in hard and abrasive materials
• Steam oxide coating improves lubricity and surface hardness
• H11 thread limit for controlled oversize tolerance in standard UNC fits

Compatibility

Designed for tapping 1/2-13 UNC threads in alloy steel, carbon steel, cast iron, stainless steel, die steel, and hardened steel. Compatible with standard 1/2-inch tap holders, quick-change tapping chucks, and CNC tapping cycles that accept straight-shank taps with a 0.367-inch shank diameter.

Installation Notes

Installation is performed by machinists or maintenance technicians using a tap wrench, drill press, or CNC machining center. Ensure the pilot hole is drilled to the correct tap drill size for 1/2-13 UNC before tapping. Apply cutting fluid appropriate to the workpiece material to extend tap life and improve thread quality. Do not reverse the tap before chips are cleared, and avoid excessive feed force when approaching the bottom of a blind hole.