Understanding Blind Rivet Nuts

Blind rivet nuts are internally threaded fasteners that can be installed from one side of a workpiece. They provide strong, load-bearing threads in thin materials that are too delicate to tap. Their design, which involves a pre-bulbed or plain shank that collapses during installation to form a strong backside flange, is what makes their removal different from other fasteners.

Methods for Removal

The best removal method often depends on the type of blind rivet nut, the material it's installed in, and the tools you have available.

1. Drilling Out the Head

This is the most common and often preferred method, especially for steel or stainless steel rivnuts.

• Identify the Rivnut Type: Some threaded inserts have a small lip or flange that sits proud of the material, while others are flush. This will guide your drilling.

• Center Punch: Using a center punch, create a small indentation in the very center of the rivet nut's head. This will prevent the drill bit from walking.

• Select the Right Drill Bit: Choose a drill bit that is slightly larger than the hole in the center of the rivnut but smaller than its outer diameter. The goal is to drill away the flared head without enlarging the primary hole in the parent material.

• Drill Slowly and Steadily: Apply moderate pressure and drill at a relatively slow speed. As you drill, the head of the threaded insert should separate. Once the head is gone, the body of the nut-sert can usually be pushed through the hole.

• Clean Up: After removal, use a deburring tool or file to clean up any rough edges around the hole.

2. Grinding Down the Head (for Flush Applications)

If the threaded insert is installed flush with the material and cannot be easily center-punched or drilled, grinding may be necessary.

• Use a Grinder with Caution: A die grinder with a small grinding bit or an angle grinder with a flap disc can be used.

• Protect the Surrounding Material: Mask off or protect the area around the rivnut to prevent accidental damage.

• Grind Incrementally: Grind down the head of the nut-sert in small increments, being careful not to overheat the material or grind into the parent surface. Once the head is thin enough, it may pop off, or you can carefully pry it.

3. Prying or Chiseling (Use with Extreme Caution)

This method should be a last resort and is generally not recommended for critical applications due to the high risk of damaging the parent material.

• Small Chisel or Pry Tool: Use a very small, sharp chisel or a thin, strong pry tool.

• Work Under the Flange: If there's any visible flange or lip, carefully try to work the tool underneath it.

• Apply Gentle Pressure: Apply very gentle and even pressure to pry the threaded insert away from the material. This method is more effective if the rivet nut was not fully crimped or if the material around it is not critical.

4. Specialized Rivnut Removal Tools (Less Common)

Some manufacturers offer specialized tools for removing their particular brand of rivnut. These are rare but can be highly effective if available. They often work by either reversing the installation process or by cleanly shearing off the head.

Important Considerations

• Material of Parent Workpiece: Always consider the material the blind rivet nut is installed in. Delicate materials like thin aluminum or plastic require extra care to prevent deformation or cracking.

• Tooling: Ensure your drill bits are sharp and the correct size. Dull bits can walk, overheat, and damage the material.

• Safety First: Always wear appropriate personal protective equipment (PPE), including safety glasses, gloves, and hearing protection, especially when drilling or grinding.

• Repairing the Hole: After removal, you may need to re-install a new nut-sert, repair the hole with a larger one, or use a different fastening method. Assess the condition of the hole and the surrounding material before proceeding.

Removing blind rivet nuts doesn't have to be a daunting task. By understanding their construction and employing the right techniques, you can effectively remove them without compromising the integrity of your project.