Heli-coil 4687-12 Hand Sti Tap M12 X 1.75 Metric Coarse

Product Description

The HELI-COIL 4687-12 is a hand STI (Screw Thread Insert) tap designed to cut the oversized internal threads required for HELI-COIL wire thread insert installation. Built from high-speed steel with a bright finish, it cuts an M12 x 1.75 metric coarse thread to a D3 thread limit. The 4-flute plug chamfer geometry provides a gradual lead-in, making it well-suited for through-hole and deeper blind-hole applications. With a thread length of approximately 1.657 inches and an overall length of approximately 3.594 inches, this tap is sized for hand-tap use in a standard tap wrench. Technicians and machinists rely on this tool when repairing stripped or damaged threads in metal components.

This tap is used during HELI-COIL thread repair and insert installation procedures across maintenance, repair, and manufacturing operations. It is appropriate for through-hole and blind-hole applications in aluminum, magnesium, mild steel, and stainless steel. Typical scenarios include stripped fastener hole repair on equipment housings, engine components, and structural assemblies where restoring thread integrity without replacing the parent part is required. The plug chamfer style makes it a common first choice when full-depth threading is needed.

Key Features

• M12 x 1.75 metric coarse thread cuts oversized STI profile for HELI-COIL insert installation
• D3 thread limit provides controlled fit for wire thread insert seating
• 4-flute plug chamfer geometry suits through-hole and deeper blind-hole threading
• High-speed steel construction handles aluminum, magnesium, mild steel, and stainless steel
• Bright finish with no coating for straightforward inspection and service life monitoring
• Compact overall length of approximately 3.594 inches fits standard hand-tap wrenches

Compatibility

Designed for use with HELI-COIL STI insert installation systems requiring an M12 x 1.75 metric coarse oversized tap. Compatible material applications include aluminum, magnesium, mild steel, and stainless steel per manufacturer specification.

Installation Notes

This tap is installed by a machinist or qualified technician using a standard hand tap wrench. Secure the workpiece before tapping, and apply appropriate cutting fluid for the parent material being threaded. Back the tap off periodically to break chips and prevent binding, especially in stainless steel. Follow the HELI-COIL system instructions for correct drill size, tap depth, and insert installation sequence before beginning the repair.