Damaged or stripped threads are a common issue in engineering, automotive, and maintenance work—but they don’t always mean scrapping the component. With a Helicoil thread repair kit, you can restore stripped threads to original strength (or even stronger) using precision-engineered inserts.

Helicoil inserts are made from stainless steel wire, wound into a diamond-shaped coil that recreates the original thread form inside a damaged hole. This simple repair method restores full functionality, maintains alignment, and prevents costly part replacement.

Let’s walk through the stages of using a Helicoil kit effectively—from preparation to installation and testing.

Tools You’ll Need

A standard Helicoil Thread Repair Kit includes everything required for a complete repair:

• Drill bit – sized for the specific insert
• Tap – special oversize thread tap for the Helicoil insert
• Installation tool – used to wind the insert into the hole
• Tang break-off tool (or punch)
• Helicoil inserts – available in standard metric or imperial sizes

You’ll also need:

• A power drill or drill press
• Cutting fluid or lubricant
• Compressed air or brush for cleaning
• Thread gauge for verification

Step 1: Identify and Prepare the Damaged Thread

Before starting, determine:

• The original thread size and pitch (e.g., M6 × 1.0, M8 × 1.25, etc.)
• The depth of the hole
• Whether the hole is blind or through

1. Remove any remaining fasteners or damaged material.
2. Clean the area thoroughly using compressed air or a degreaser.
3. Mark and secure the workpiece for drilling.

Step 2: Drill Out the Oversize Hole

Using the drill bit supplied in your Helicoil kit (or the specified size from the chart), drill the new oversize hole for the Helicoil thread seat.

• Keep the drill square to the surface.
• Use steady pressure and cutting fluid to avoid overheating.
• Drill to the correct depth for the new insert.

Once complete, clean the hole to remove all chips and debris.

Step 3: Tap the New Thread

Next, use the Helicoil tap provided to cut a new oversize thread inside the hole. This thread will accommodate the stainless steel insert.

1. Apply cutting fluid to the tap.
2. Turn slowly and evenly—half a turn forward, then a quarter back to break chips.
3. Continue until the tap reaches full depth.
4. Remove the tap and clean the hole again thoroughly.

Tip: Avoid cross-threading—the tap should turn smoothly. If resistance is high, remove it, clean, and start again.

Step 4: Install the Helicoil Insert

Thread a Helicoil insert onto the installation tool, engaging the tang (drive notch) at the bottom.

1. Insert the coil into the newly tapped hole.
2. Rotate the tool clockwise to wind the insert in—it should sit ¼ to ½ turn below the surface.
3. Once fully seated, remove the installation tool carefully.

This step recreates the original internal thread size and pitch.

Step 5: Break Off the Tang

After installation, use the tang break tool (or a small punch) to remove the tang at the bottom of the insert.

1. Position the punch directly on the tang.
2. Apply a sharp, controlled tap with a hammer.
3. Remove the tang fragment from the hole.

Note: Some through holes allow the tang to fall through—ensure no debris remains before inserting a bolt.

Step 6: Test and Finish

Finally, test the repair:

1. Thread in the original bolt or fastener by hand.
2. Ensure it seats smoothly and feels firm with no binding or looseness.
3. Torque the bolt to specification—your repaired thread should now perform like new.

Benefits of Using a Helicoil Insert

• Restores damaged threads to original size and strength
• Increases thread life—stainless steel insert resists wear and corrosion
• Prevents future stripping in softer materials like aluminium
• Maintains accuracy—perfect thread alignment and load distribution
• Cost-effective alternative to replacement parts

Conclusion

Using a Helicoil thread repair kit is one of the most efficient and reliable ways to fix stripped threads in metal components. With proper preparation and careful installation, you can restore full thread integrity in just a few minutes.

Whether in automotive, aerospace, or general machining applications, Helicoil inserts are a proven solution for durability, precision, and strength.

Twin Eagle Imports supplies a complete range of Helicoil thread repair kits, spare inserts, and installation accessories suitable for metric, UNC, UNF, and BSW applications—trusted by professionals across Australia for performance and reliability.