Osg 12800500 Sti Hand Tap M5 X 0.8 Metric Coarse D3

Product Description

The OSG 12800500 is an STI (Screw Thread Insert) hand tap ground to M5 x 0.8 Metric Coarse thread form with a D3 thread limit and modified bottoming chamfer. It is manufactured from high-speed steel with a bright finish and features 3 flutes for chip evacuation during hand tapping operations. The tap produces oversized internal threads designed to accept helical wire inserts such as Heli-Coil style inserts, restoring or upgrading threaded holes in a wide range of base materials. Overall length is 2.5 inches with a 1.0-inch thread length and a shank diameter of 0.255 inches. Class of fit is 6H. The part weighs 0.03 pounds.

This tap is suited for repair and new-thread applications in aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel. It is used by machinists, maintenance technicians, and field service professionals wherever a stripped or damaged M5 threaded hole must be restored using a wire thread insert. The modified bottoming chamfer allows threading closer to the bottom of a blind hole compared to a standard taper chamfer, making it practical for shallow-hole applications.

Key Features

• STI thread form — produces oversized threads sized for helical wire thread inserts
• Modified bottoming chamfer for threading near the base of blind holes
• High-speed steel construction for durability across a range of workpiece materials
• 3-flute geometry aids chip clearance during hand tapping
• D3 thread limit and 6H class of fit for consistent insert installation
• Bright finish — no coating to affect dimensional accuracy

Compatibility

Designed for use with helical wire thread inserts in M5 x 0.8 Metric Coarse applications. Compatible base materials include aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel per OSG Series 128 specifications.

Installation Notes

This tap is intended for hand tapping only — use a proper tap wrench and apply consistent downward pressure with periodic reverse strokes to break chips. Secure the workpiece firmly before starting and align the tap perpendicular to the hole to avoid tap breakage. Always drill with the correct STI tap drill size for M5 x 0.8 inserts before tapping; using a standard M5 drill diameter will result in undersized threads. Apply an appropriate cutting fluid matched to the workpiece material.