Osg 2936801 Spiral Flute Tap 3/8-24 Unf Vanadium Hss

Product Description

The OSG 2936801 is a spiral flute tap designed to cut 3/8-24 UNF internal threads in a range of ferrous metals. Built from vanadium high-speed steel with a steam oxide coating, it operates as a modified bottoming tap, meaning the chamfer is shortened to allow threading closer to the bottom of a blind hole. The 45-degree helix angle evacuates chips upward out of the hole, making it well-suited for blind-hole applications where chip packing is a common failure point. The tap is ground to an H4 thread limit and a 2B class of fit, which is the standard commercial tolerance for general fastener threads. Overall length is 2.938 inches.

This tap is used in machine shop, maintenance, and production environments where 3/8-24 UNF threads are required in blind holes. Material applications include alloy steel, carbon steel, cast iron, stainless steel, die steel, and hardened steel. The modified bottoming chamfer makes it the right choice when a standard taper or plug tap cannot reach thread depth. It is used in CNC tapping, turret lathes, drill presses with tapping attachments, and hand tapping operations where the operator needs control close to the bottom of the hole.

Key Features

• 45-degree right-hand spiral flute evacuates chips upward, reducing packing in blind holes
• Modified bottoming chamfer threads closer to hole bottom than plug or taper styles
• Vanadium high-speed steel construction provides hardness and wear resistance in ferrous materials
• Steam oxide coating reduces friction and provides light corrosion resistance during storage and use
• H4 thread limit ground to 2B class of fit for standard commercial thread tolerance
• 3 flutes with right-hand thread direction; no coolant-through feature

Compatibility

Designed for cutting 3/8-24 UNF 2B class threads in alloy steel, carbon steel, cast iron, stainless steel, die steel, and hardened steel workpieces. Part of OSG Series 290.

Installation Notes

This tap is installed by machinists and tool and die professionals using a tap wrench, tapping head, or CNC rigid tapping cycle. Before use, ensure the pilot hole is drilled to the correct tap drill diameter for 3/8-24 UNF to achieve proper thread engagement. Use an appropriate cutting fluid for the workpiece material, particularly when tapping stainless or alloy steel. Do not exceed the recommended speed for the material and tap size, and never reverse a spiral flute tap under power without confirming the tapping attachment supports it.