STI-Twist Drill, 5.1  mm

V-COIL STI Twist Drill, 5.1 mm

When it comes to preparing threads for repair with absolute precision, the V-COIL STI Twist Drill (5.1 mm) is an essential specialist tool. Designed specifically for enlarging the core hole of a damaged thread, this drill ensures the perfect fit for cutting an STI (Screw Thread Insert) thread. It’s the crucial first step in the V-COIL thread repair process.

What is this product and what does it do?

The V-COIL STI Twist Drill is a specially sized drill bit engineered to enlarge the core hole of a worn or damaged internal thread to the exact diameter required for an STI thread insert.

• Core Hole Enlargement: Its main function is to precisely drill out the existing, damaged thread, creating a perfectly dimensioned hole for the STI tap. This isn’t just about removing the old thread—it’s about preparing the ideal foundation for a strong, lasting repair.
• Part of the V-COIL System: This drill is an integral part of the V-COIL thread repair system, which restores threads to their original size or creates high-strength threads in softer materials.
• Specialized Size: The 5.1 mm diameter isn’t a standard metric core hole size; it’s tailored specifically for the subsequent STI tap.

How and when is it used?

The V-COIL STI Twist Drill is used whenever a V-COIL thread insert is needed, such as:

• Repairing damaged or worn threads: Perfect for restoring internal threads in components like engine blocks or aluminum parts, where a durable, reliable repair is required.
• Creating high-strength threads in soft materials: In materials like aluminum, magnesium, or plastics, a V-COIL insert significantly increases thread strength.

Typical steps in the V-COIL repair process:

1. Enlarge the core hole: Use the V-COIL STI Twist Drill to remove the damaged thread and create the precise hole for the STI tap. Accuracy and straightness are key.
2. Cut the STI thread: Use the special V-COIL STI tap to cut the new, larger thread.
3. Install the thread insert: Insert the V-COIL wire insert using the dedicated installation tool.
4. Break off the tang: Snap off the tang of the insert to finish the repair.

Materials:
This drill is suitable for:

• Machinable materials up to 900 N/mm²
• Unalloyed and low-alloy steels
• Commonly used in aluminum, magnesium, and other non-ferrous metals

Key Advantages

• Precision-matched: Perfectly sized for V-COIL STI taps, ensuring optimal repair quality.
• Easy to use: Designed to drill out old threads cleanly, using the existing thread as a guide.
• Part of a proven system: Trusted for creating high-strength, long-lasting repairs.
• Flexible availability: Available individually or in convenient sets.
• Broad size range: Available from 2.1 mm to 13.0 mm for various thread sizes.
• Cost-saving: Enables repair of expensive parts, reducing replacement costs and downtime.
• Specialized for thread repair: Unlike standard twist drills, this drill is purpose-built for thread repair applications.