Osg 2103801 Extension Tap 3/8-16 Spiral Point Hss

Product Description

The OSG 2103801 is a spiral point plug extension tap designed for right-hand threading in a range of metalworking applications. Built from high-speed steel with a steam oxide finish, it cuts 3/8-16 UNC threads to a 3B class of fit with an H3 thread limit. The tap measures 4 inches overall length with a 1 inch thread length and features three flutes with a plug chamfer style. The reduced shank design enables reach into deeper or extended-clearance work areas where standard-length taps cannot access. Licensed machinists, tool and die makers, and maintenance technicians are the primary users of this tap in production and repair threading operations.

This extension tap is suited for threading through-holes in cast iron, aluminum castings, aluminum, and carbon steel workpieces. The spiral point geometry pushes chips forward ahead of the tap, making it well-suited for through-hole threading on CNC machines, drill presses, and manual tapping setups. The plug chamfer provides a gradual lead into the cut, making it appropriate for production runs and repair threading where thread quality and tool life consistency matter. Its extended reach is particularly useful in fixtures or assemblies where access is limited.

Key Features

• Spiral point geometry pushes chips forward, optimizing through-hole threading performance
• High-speed steel construction provides durability across cast iron, aluminum, and carbon steel
• Steam oxide finish reduces friction and improves lubrication retention during the cut
• H3 thread limit and 3B class of fit ensure consistent, gauged thread production
• Reduced shank extends reach for use in restricted or deep-clearance applications
• Three flutes with right-hand flute direction and plug chamfer for smooth thread entry

Compatibility

Designed for threading 3/8-16 UNC right-hand through-holes in cast iron, aluminum castings, aluminum, and carbon steel. Belongs to OSG Series 917.

Installation Notes

This tap is installed and driven by a qualified machinist or maintenance technician using a standard tap wrench, tapping head, or CNC rigid-tapping spindle sized for the square drive. Ensure the workpiece is securely fixtured and the hole is drilled to the correct tap drill diameter for 3/8-16 UNC threads before beginning. Apply appropriate cutting fluid for the workpiece material to extend tool life and improve thread finish. Follow shop safety procedures and applicable tooling standards when operating tapping equipment.