Osg 1121201 Straight Flute Tap 3/8-16 Unc Hss Oxide

Product Description

The OSG 1121201 is a straight flute hand tap designed for cutting 3/8-16 UNC right-hand threads in a variety of ferrous and non-ferrous materials. Built from high-speed steel with an oxide coating for improved lubricity and wear resistance, this tap features a taper chamfer that guides the tool into the workpiece gradually, distributing cutting forces across multiple leading threads. With 4 flutes and an H3 thread limit, it is suited for producing Class 3B fit threads that meet general-purpose tolerance requirements. The overall length is 2-15/16 inches with a thread length of 1-1/4 inches, making it a standard-proportioned tap for most benchtop or machine-assisted hand-tapping applications.

This tap is intended for use in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. The taper chamfer style makes it the preferred starting tap when threading a through hole or when beginning a blind hole sequence. Machinists, toolroom technicians, and maintenance professionals use this tap in drill presses, tapping fixtures, or by hand with a standard tap wrench. It belongs to OSG Series 101, a widely stocked straight flute tap line for general industrial and MRO use.

Key Features

• 3/8-16 UNC thread form with right-hand direction and Class 3B fit
• H3 thread limit for controlled oversize tolerance in standard steel and aluminum applications
• Taper chamfer distributes cutting load across 7-10 leading threads for easier thread starting
• High-speed steel construction provides toughness across a broad range of workpiece materials
• Oxide coating reduces friction and improves chip flow during tapping
• 4-flute design offers balanced cutting action and good chip clearance in short-chipping materials

Compatibility

Suitable for tapping 3/8-16 UNC threads in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. Functions in standard tap holders, tapping heads, and hand tap wrenches that accept a straight shank with a 0.381-inch shank diameter.

Installation Notes

This tap is installed by a machinist or maintenance technician using a tap wrench, tapping fixture, or low-speed drill press with a tapping attachment. Always use an appropriate cutting fluid matched to the workpiece material to extend tool life and improve thread finish. Ensure the tap is started square to the hole to avoid thread misalignment or tap breakage. Follow applicable shop safety procedures and secure the workpiece firmly before beginning the tapping operation.