Osg 6014400 Sti Hand Tap 1/4-28 Unf H3 Plug Chamfer

Product Description

The OSG 6014400 is a straight-flute STI (Screw Thread Insert) hand tap designed for cutting 1/4-28 UNF threads to accept helical wire thread inserts such as Heli-Coil or equivalent. Built from high speed steel (HSS) with a bright finish, the tap features a plug chamfer entry of 3-5 threads for ease of starting in through-holes and blind holes with adequate depth. The H3 thread limit provides controlled tolerance for consistent insert fitment. With 3 flutes and a 1-inch thread length, this tap is suited for manual tapping operations where chip clearance and thread quality are the primary concerns.

STI hand taps are used in maintenance, repair, and manufacturing settings where damaged or stripped threads are being restored using wire thread inserts. This tap is appropriate for use in aluminum, carbon steel, cast iron, and hardened steel workpieces. Machinists, maintenance technicians, and tool and die professionals use this style of tap when threading holes that will receive a threaded insert rather than a fastener directly. It is commonly used in aerospace, automotive, and general industrial repair applications.

Key Features

• STI (Screw Thread Insert) geometry sized for 1/4-28 UNF helical insert installation
• H3 thread limit for consistent, controlled tolerance thread production
• Plug chamfer (3-5 thread lead) for straightforward starting in through or deep blind holes
• 3-flute design provides good chip evacuation during hand tapping
• High speed steel construction rated for use in aluminum, carbon steel, cast iron, and hardened steel
• Bright finish - no coating - allows visual wear inspection and suits general-purpose use

Compatibility

Designed for use with 1/4-28 UNF helical wire thread inserts. Compatible workpiece materials include aluminum, carbon steel, cast iron, and hardened steel as specified by the manufacturer.

Installation Notes

This is a hand tap intended for use with a tap wrench or T-handle; it is not designed for machine-driven operation. Secure the workpiece firmly before tapping and apply appropriate cutting fluid for the workpiece material to extend tool life and improve thread finish. Back off the tap periodically to break chips and prevent tap breakage, particularly in blind holes. Follow applicable shop safety practices and ensure the tap is properly aligned with the hole axis before applying torque.