How To Use Rivnuts – The Ultimate Guide To Professional Threaded
To use a rivnut, drill a hole in your material that matches the outer diameter of the insert, then thread the rivnut onto the mandrel of a specialized setting tool. Insert it into the hole and squeeze the tool handles to collapse the fastener’s sleeve, creating a permanent threaded anchor in thin or hollow materials.
This “blind” fastening method is ideal for projects where you cannot reach the backside of the material to place a traditional nut, such as in vehicle frames, square tubing, or sheet metal panels.
Have you ever tried to bolt a bracket to thin sheet metal or a hollow square tube only to realize there is no way to get a nut on the back? It is a common frustration in the garage that often leads to using weak self-tapping screws that eventually strip out and fail.
I promise that learning how to use rivnuts will completely transform your approach to metalworking and custom DIY builds. These clever fasteners, also known as rivet nuts or threaded inserts, provide a rock-solid, load-bearing thread in materials that are otherwise too thin to tap.
In the following guide, we will cover everything from tool selection to the subtle “feel” of a perfectly set insert. Whether you are outfitting a camper van or building custom shop furniture, this technique is a must-have skill for any serious tinkerer.
What Exactly is a Rivet Nut?
Before we dive into the mechanics, let’s define the hardware. A rivnut is a one-piece internally threaded tubular rivet that can be anchored entirely from one side of the workpiece. This makes it a blind fastener, perfect for closed-off areas like frame rails or thin-walled tubing.
When you use the setting tool, it pulls the threaded portion of the nut toward the head. This action causes the unthreaded middle section to collapse outward, sandwiching the base material between the head of the nut and the newly formed flange on the backside.
The result is a permanent, threaded hole that accepts standard machine bolts. Because the insert is usually knurled or hexagonal, it bites into the material to prevent spinning when you tighten your bolt later on.
Essential Tools and Materials for the Job
You don’t need a massive industrial setup to get started, but having the right specialized gear makes a world of difference. To master how to use rivnuts, you should gather a few specific items before you start drilling into your project.
- The Rivnut Tool: This looks like a heavy-duty pop-rivet gun but features a threaded mandrel and nosepiece. High-quality tools often come with interchangeable mandrels for different thread sizes (M5, M6, 1/4-20, etc.).
- Threaded Inserts: These come in various materials like aluminum, steel, and stainless steel. You must match the material of the insert to the material of your workpiece to prevent galvanic corrosion.
- Step Drill Bits: A standard twist bit works, but a step bit (Unibit) often creates a cleaner, more precise hole in thin sheet metal, which is critical for a tight fit.
- Deburring Tool: Any burrs left around the hole can prevent the rivnut from sitting flush against the surface, leading to a weak connection.
Step-by-Step: How to Use Rivnuts for a Professional Finish
Installation is a straightforward process, but precision is key. If the hole is too large, the insert will spin; if you squeeze too hard, you might strip the threads or break the tool’s mandrel. Follow these steps for a perfect set every time.
1. Size the Hole Correctly
Check the packaging of your inserts to find the required hole diameter. This is usually slightly larger than the outer diameter of the rivnut body. I recommend testing on a scrap piece of the same material first to ensure the fit is snug but not forced.
2. Prep the Surface
Drill your hole using a steady hand and moderate speed. Once the hole is through, use a deburring tool or a larger drill bit to lightly clean the edges. You want the underside of the rivnut head to make full contact with the metal surface.
3. Load the Tool
Select the mandrel that matches your rivnut’s internal thread. Open the handles of the tool and thread the rivnut onto the mandrel until the head of the nut is flush against the nosepiece. Most tools have a knurled knob on the back to make this easier.
4. Set the Insert
Push the rivnut into your pre-drilled hole. Ensure the tool is held perfectly perpendicular to the surface. Squeeze the handles firmly and steadily. You will feel the resistance increase as the sleeve collapses on the backside.
5. Release and Inspect
Once the handles are fully closed (or you feel a significant increase in resistance), stop squeezing. Use the rear knob to unscrew the mandrel from the now-installed insert. The rivnut should be tight, flush, and should not wiggle or spin when you touch it.
Choosing the Right Type of Rivet Nut
Not all inserts are created equal. Mastering how to use rivnuts involves knowing which material and style fits your specific application. Using the wrong one can lead to failure under vibration or heavy loads.
Material Selection
Aluminum inserts are easy to set and great for lightweight projects or aluminum panels. However, for structural automotive work or heavy-duty brackets, zinc-plated steel or stainless steel is required for higher shear strength.
Grip Range
Every rivnut has a specific grip range, which refers to the thickness of the material it can successfully clamp. If your metal is too thin for the insert, it won’t collapse tightly. If the metal is too thick, the “bulge” won’t form correctly on the backside.
Body Styles
Smooth-bodied inserts are common but can spin if the bolt gets seized. Knurled bodies provide extra grip against the walls of the hole. For the ultimate “anti-spin” security, some builders use hexagonal inserts, though these require a special hex-shaped hole punch or file.
Common Mistakes and How to Troubleshooting
Even experienced builders run into issues when they first learn how to use rivnuts. The most common nightmare is the “spinning insert,” where the entire nut turns along with the bolt you are trying to tighten.
If an insert starts to spin, it usually means the hole was too large or the nut wasn’t collapsed enough. You can sometimes fix this by re-inserting the tool and giving it another small squeeze to tighten the grip.
Another pitfall is over-torquing the tool. If you use a large two-handed tool on a small M4 aluminum insert, it is very easy to snap the mandrel or strip the internal threads. Always “feel” the resistance rather than relying on pure muscle.
Real-World Applications for the DIY Workshop
Once you understand how to use rivnuts, you will find uses for them everywhere. In my workshop, I use them to mount organizer racks to the side of metal tool cabinets where I can’t reach the inside.
For automotive DIYers, these are lifesavers. They allow you to add skid plates, light bars, or interior shelving to a van without having to remove interior trim to reach the back of a panel. They are also excellent for attaching wooden accents to metal furniture frames.
Frequently Asked Questions About How to Use Rivnuts
Can I use rivnuts in wood or plastic?
While designed for metal, they can work in hard plastics or dense composites. However, for wood, you are usually better off using threaded wood inserts (like E-Z LOK) which have deep external threads designed to bite into wood fibers.
What do I do if I don’t have the special tool?
You can make a DIY setter using a high-grade bolt, a nut, and two washers. Thread the nut onto the bolt, then the washers, then the rivnut. Hold the bolt head still with one wrench and turn the nut with another to pull the rivnut tight. It is slower but works in a pinch.
How much weight can a rivnut hold?
This depends on the material and thread size. A steel M6 rivnut in 1/8″ steel can often handle hundreds of pounds of tensile force. Always check the manufacturer’s load ratings if you are building something safety-critical, like a roof rack.
Can I remove a rivnut if I mess up?
Yes. You can drill out a rivnut just like a standard rivet. Choose a drill bit slightly larger than the internal thread but smaller than the outer flange. Drill through the head until it pops off, then push the remaining sleeve into the hole.
Final Thoughts on Mastering Threaded Inserts
Adding this skill to your DIY arsenal is a total game-changer. It bridges the gap between simple sheet metal work and professional-grade fabrication. The ability to create a serviceable connection—one that you can bolt and unbolt repeatedly—is what separates a “hack job” from a professional build.
Take your time, always do a test piece, and invest in a decent tool with a comfortable grip. Once you see how clean and secure the results are, you’ll never go back to using sheet metal screws again. Now, get out to the garage and start practicing!
