Heli-coil 4687-4 Hand Sti Tap M4 X 0.7 Metric Coarse

Product Description

The HELI-COIL 4687-4 is a hand STI (Screw Thread Insert) tap designed to cut the oversized internal threads required for installing Heli-Coil wire thread inserts. Sized at M4 x 0.7 metric coarse with a D2 thread limit, it cuts a 3-flute plug chamfer profile through a thread length of 22.22 mm and an overall length of 60.32 mm. The tap is ground from high speed steel with a bright finish, giving it the hardness and edge retention needed for consistent thread prep across a range of materials. It is the correct tool to use before driving a Heli-Coil insert in stripped or new-bore holes.

This tap is suited for use in maintenance, repair, and manufacturing environments where stripped threads are being restored or new thread inserts are being installed. Rated for use in aluminum, magnesium, mild steel, and stainless steel, it handles the material range common to light industrial, automotive, aerospace, and general fabrication work. The M4 x 0.7 size is a common metric fastener thread found throughout machinery, engines, and enclosures, making this tap a practical addition to any insert-repair kit.

Key Features

• Cuts STI-profile threads sized for M4 x 0.7 Heli-Coil wire thread inserts
• 3-flute geometry with plug chamfer for progressive thread engagement on through-holes and blind holes with adequate depth
• D2 thread limit controls fit and tolerance consistency across production or repair use
• High speed steel construction provides hardness suitable for stainless steel and other tough materials
• Bright finish - uncoated - allows clear visual inspection of cutting edges before and after use
• Shank diameter of 4.93 mm fits standard tap wrenches and machine holders for M4-range taps

Compatibility

Designed for use with Heli-Coil STI insert systems requiring M4 x 0.7 metric coarse thread preparation. Compatible with aluminum, magnesium, mild steel, and stainless steel workpieces as stated by the manufacturer.

Installation Notes

A licensed machinist or trained technician should select the correct tap drill size per the Heli-Coil specification chart before tapping. Secure the workpiece and use a properly aligned tap wrench to avoid tap breakage, particularly in stainless steel. Apply appropriate cutting fluid for the base material to extend tap life and improve thread finish. Inspect cutting flutes before each use - a chipped or dull tap will produce out-of-tolerance threads that will not seat the insert correctly.