Osg 2942901 Spiral Flute Tap 1/2-20 Unf Vanadium Hss

Product Description

The OSG 2942901 is a spiral flute tap designed for cutting 1/2-20 UNF right-hand internal threads in a range of ferrous and alloy materials. Built from 3 percent vanadium high-speed steel (HSS) with a steam oxide finish, it delivers improved wear resistance and lubricity compared to standard HSS taps. The modified bottoming chamfer allows threading closer to the bottom of blind holes. With 3 right-hand spiral flutes at a 45-degree helix angle, the tap efficiently evacuates chips back out of the hole during cutting. Overall length is 3.375 inches. Licensed machinists and tool-and-die professionals are the primary users of this tap.

This tap is suited for blind-hole threading applications in alloy steel, carbon steel, cast iron, stainless steel, die steel, and hardened steel workpieces. The 45-degree helix and spiral flute geometry make it particularly effective in materials that produce stringy chips, since the flute design pulls chips upward and out of the hole. It fits standard tap holders and machines configured for 1/2-20 UNF threading on manual mills, CNC machining centers, and drill presses where controlled feed tapping is used. Thread limit is H7, which is an oversize designation appropriate for plated or tight-tolerance UNF holes.

Key Features

• 1/2-20 UNF thread form with right-hand thread direction
• 3 percent vanadium HSS construction for extended tool life in ferrous materials
• 45-degree helix angle spiral flutes for upward chip evacuation in blind holes
• Modified bottoming chamfer for threading close to blind hole floors
• Steam oxide coating improves lubricity and corrosion resistance
• H7 oversize thread limit suitable for plated-hole applications

Compatibility

Designed for use in alloy steel, carbon steel, cast iron, stainless steel, die steel, and hardened steel. Fits standard 1/2-inch tap holders and compatible with machines set up for 1/2-20 UNF threading operations.

Installation Notes

This tap is installed by qualified machinists using a tap wrench, tapping head, or rigid CNC tapping cycle. Use a cutting fluid appropriate for the workpiece material - sulfurized oil is commonly recommended for steel. Secure the workpiece and ensure the tap is started square to the drilled hole to prevent tap breakage. For blind holes, verify hole depth before tapping to avoid bottoming out the tap body against the hole floor.