Osg 1301403901 Spiral Flute Tap 1-3/8-12 Unf 5 Flutes

Product Description

The OSG 1301403901 is a spiral flute tap designed to cut 1-3/8-12 UNF internal threads in a range of ferrous workpiece materials. It features 5 right-hand spiral flutes with a 15-degree helix angle that evacuates chips up and out of the hole during tapping, making it well suited for blind-hole applications where chip packing is a concern. The modified bottoming chamfer allows threading closer to the bottom of a hole than a standard plug tap. Manufactured from vanadium high-speed steel and finished with an oxide coating, this tap is built for production and maintenance tapping in alloy steel, carbon steel, cast iron, stainless steel, die steel, and hardened steel. It meets a 2B class of fit, the standard commercial tolerance for unified inch threads.

This tap is used in machining, maintenance, and toolroom environments wherever 1-3/8-12 UNF threaded holes are required. The modified bottoming geometry is common in applications that demand full thread engagement near the base of a blind bore, such as hydraulic ports, fixture components, and structural fastener holes. A licensed machinist or toolroom technician typically selects this tap for use in CNC machining centers, knee mills, or manual drill presses equipped with a tapping head. The 2B class of fit is appropriate for the majority of standard-clearance threaded fastener assemblies.

Key Features

• 1-3/8-12 UNF right-hand thread form, 2B class of fit for standard commercial tolerance
• 5 spiral flutes with 15-degree helix angle for upward chip evacuation in blind holes
• Modified bottoming chamfer for threading closer to the base of blind bores
• Vanadium high-speed steel construction for toughness and wear resistance in ferrous materials
• Oxide coating provides mild lubricity and corrosion protection during storage and use
• No coolant-through design; suitable for flood or manual lubrication setups

Compatibility

Designed for tapping alloy steel, carbon steel, cast iron, stainless steel, die steel, and hardened steel workpieces. Material application codes P, M, K, and H confirm suitability across a broad range of ferrous and hardened materials. Part of OSG Series 13014.

Installation Notes

A machinist or toolroom technician should install this tap using a properly sized tap holder or tapping head matched to the shank diameter. Power down the machine and secure the workpiece before setting up the tap. Always use an appropriate cutting fluid for the workpiece material to extend tool life and maintain thread quality. Follow applicable shop safety standards and verify starting hole diameter against the recommended tap drill size for 1-3/8-12 UNF before tapping.