Osg 2933801 Spiral Flute Tap 3/4-16 Unf 4 Flute Modified Bottoming

Product Description

The OSG 2933801 is a spiral flute tap designed for cutting 3/4-16 UNF internal threads in blind holes and through holes where chip evacuation is critical. Built from vanadium high-speed steel and finished with a steam oxide coating, this tap runs in right-hand rotation with a 45-degree helix angle that pulls chips up and out of the hole during the tapping cycle. The modified bottoming chamfer allows threading close to the bottom of a blind hole. Rated to Class 3B fit with an H3 thread limit, it is suited for precision fastener applications where tight tolerance threads are required. This is a shop-grade tool installed by machinists, maintenance technicians, and tool-and-die professionals.

The 2933801 is engineered for use in a wide range of ferrous and hard materials including alloy steel, carbon steel, cast iron, stainless steel, die steel, and hardened steel. Its spiral flute geometry makes it especially effective in blind-hole applications where straight-flute taps would pack chips. It fits standard tap holders and is compatible with CNC machining centers, drill presses, and manual tapping arms. The Series 290 designation places it in OSG's professional-grade tapping line intended for production and maintenance environments.

Key Features

• 3/4-16 UNF thread form, Class 3B fit, H3 thread limit for precision tolerance control
• 45-degree right-hand spiral flute geometry evacuates chips upward — ideal for blind holes
• Modified bottoming chamfer allows threading to near the bottom of a blind hole
• Vanadium high-speed steel construction provides wear resistance in tough ferrous materials
• Steam oxide coating reduces friction and provides mild corrosion resistance during storage and use
• 4 flutes for increased thread contact and smoother cutting action

Compatibility

Designed for tapping 3/4-16 UNF threads in alloy steel, carbon steel, cast iron, stainless steel, die steel, and hardened steel workpieces. Fits standard 3/4-inch tap holders and collet-style tap chucks used in CNC and manual tapping setups.

Installation Notes

Secure the tap in a properly sized tap holder or floating tap chuck before use. Always apply cutting fluid appropriate for the workpiece material, particularly when tapping stainless or hardened steel. Ensure the spindle is aligned perpendicular to the workpiece to avoid tap deflection and thread galling. For CNC applications, program feed rate to match the 16 TPI pitch exactly to prevent thread damage or tap breakage.