Osg 1591601 Spiral Point Tap 3/8-16 Unc Hss Plug

Product Description

The OSG 1591601 is a spiral point plug tap designed for threading through-holes in a wide range of metals. Built from high-speed steel with a steam oxide coating, this 3/8-16 UNC tap features 3 flutes and a plug chamfer that progressively cuts threads while pushing chips forward ahead of the tap. The right-hand cut and 0.005 inch oversize tolerance make it suitable for applications requiring a slightly larger thread fit. Overall length is 2.938 inches with a thread length of 0.787 inches and a shank diameter of 0.381 inches. Licensed machinists, maintenance technicians, and tool room operators are the typical users.

This tap is well suited for production and maintenance threading operations in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, high-carbon steel, and hardened steel. The spiral point geometry is designed specifically for through-hole applications where chips can be advanced ahead of the cutting zone rather than packed in a blind bore. It is a strong choice for CNC tapping, turret lathe work, and hand tapping in general metalworking environments.

Key Features

• 3/8-16 UNC thread form, right-hand direction
• Plug chamfer for progressive thread cutting entry
• 3-flute spiral point design pushes chips forward, ideal for through-holes
• High-speed steel construction for durability across ferrous and non-ferrous materials
• Steam oxide coating reduces friction and helps with initial chip buildup
• +0.005 inch oversize for controlled thread tolerance
• Series 105H designation for consistent replacement sourcing

Compatibility

Designed for threading 3/8-16 UNC through-holes in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, high-carbon steel, and hardened steel. Not intended for blind-hole applications where chip evacuation forward is not possible.

Installation Notes

Secure the tap in an appropriate tap holder, chuck, or tapping head before use; never use an ill-fitting holder that allows runout. Apply a suitable cutting fluid matched to the workpiece material to extend tap life and improve thread finish. Ensure the workpiece is firmly clamped and the tap is aligned perpendicular to the hole before engaging. Follow standard shop safety practices and manufacturer feeds and speeds guidance for high-speed steel tooling.