Types Of Rivet Nuts – Choosing The Right Fastener For Your Metal

ByJim Boslice Metalworking & Fabrication

Rivet nuts (or nutserts) are threaded inserts used to create reliable, load-bearing threads in thin materials where traditional tapping isn’t possible. Choosing the right one depends on your material thickness, the required grip range, and the environmental exposure of your project.

You have spent hours cutting, grinding, and welding your latest fabrication project, only to realize you need a secure way to bolt on a bracket or a handle. Tapping a thread into thin sheet metal is a recipe for frustration because there simply isn’t enough material for the bolt to bite into.

This is where understanding the different types of rivet nuts changes everything. They act as a permanent, threaded anchor that you can install from just one side of the work, saving you from needing access to the back of the panel.

Whether you are a garage tinkerer or a dedicated metalworker, selecting the correct hardware ensures your project stays together under vibration and load. Let’s dive into how these fasteners work and which ones belong in your shop inventory.

Understanding the Core Types of Rivet Nuts

Before you head to the hardware store, you need to know that not all inserts are created equal. The types of rivet nuts available generally fall into categories based on their body shape, head profile, and material composition.

Most common inserts are either cylindrical or hexagonal. Cylindrical bodies are standard, but hexagonal bodies provide much better resistance to spinning inside the hole if you accidentally over-torque a bolt later on.

You also have to decide between open-end or closed-end designs. Open-end versions are cheaper and more common, while closed-end rivet nuts offer a seal against moisture and debris, which is critical for automotive or outdoor applications.

Matching Head Profiles to Your Project

The head profile determines how the fastener sits on your surface once it is fully compressed. Your choice here impacts both the aesthetics and the structural fit of your components.

Flat Head Rivet Nuts

These are the most common variety. The head sits on top of the surface, which is fine if you are bolting a bracket on top of a flat panel.

The downside is that it creates a small gap between the bracket and the sheet metal. If your project requires a perfectly flush mating surface, you will need to choose a different style.

Countersunk (Flush) Rivet Nuts

If you need your surface to remain perfectly flat, use a countersunk insert. These require you to dimple or chamfer the hole first so the head sits flush with the surrounding metal.

These provide a clean, professional finish that looks great on vehicle bodywork or custom metal furniture. They do require a bit more prep time, but the visual payoff is well worth the extra effort.

Material Selection and Corrosion Resistance

Material compatibility is a rule often ignored by beginners, but it is vital for long-term durability. Never mix dissimilar metals if your project is going to live outside or in a humid environment.

  • Aluminum: Lightweight and easy to install. Perfect for indoor projects or non-structural automotive trim.
  • Steel: The workhorse of the shop. Strong and reliable, but it will rust if left unfinished. Always paint or seal steel inserts.
  • Stainless Steel: The gold standard for outdoor projects. It resists corrosion, though it is significantly harder to install and requires a heavy-duty tool.

If you are working with aluminum chassis components, stick to aluminum fasteners to avoid galvanic corrosion. This happens when two different metals react in the presence of moisture, effectively eating away at your project.

Step-by-Step Installation Basics

Installing these fasteners is straightforward if you have the right tool. You will need a rivet nut setting tool, which acts similarly to a pop rivet gun by pulling the threaded mandrel to collapse the insert.

  1. Drill the hole: Use a high-quality drill bit that matches the manufacturer’s recommended hole size. A hole that is too big will result in a loose, spinning fastener.
  2. Deburr the edges: Use a file or a countersink bit to remove sharp burrs from the hole. This ensures the insert seats flat against the surface.
  3. Thread the insert: Screw the rivet nut onto the mandrel of your installation tool until it is seated firmly against the nose piece.
  4. Compress: Insert the fastener into the hole and actuate the tool. The back of the insert will buckle and “mushroom” against the backside of the panel.
  5. Remove the tool: Unthread the mandrel, leaving a perfectly installed, threaded anchor in your metal.

Troubleshooting Common Installation Issues

Even with the best tools, things can go wrong. The most common mistake is failing to account for grip range. If the material is too thin for the fastener, it won’t collapse properly, and the insert will feel loose.

If you find your fastener spinning in the hole, you likely drilled the hole slightly too large. For future projects, consider using hexagonal inserts, which lock into a hex-shaped hole and physically cannot rotate.

Another frequent issue is stripping the threads during installation. This usually happens if you try to “over-squeeze” the tool. Apply firm, steady pressure, but don’t force it beyond the point of resistance.

Frequently Asked Questions About Rivet Nuts

Can I install a rivet nut without a special tool?

Technically, yes. You can use a bolt, a nut, and two wrenches to create a DIY installation setup. By tightening the nut against the insert while holding the bolt steady, you can collapse the fastener. However, for anything more than a one-off repair, a proper dedicated tool is safer and much more consistent.

How do I know which size to buy?

Always check the manufacturer’s technical data sheet for the specific insert. You need to know the thread size (e.g., M6 or 1/4-20) and the “grip range,” which is the thickness of the metal you are attaching it to. If your metal is 0.040 inches thick, ensure that thickness falls within the fastener’s specified range.

Are rivet nuts strong enough for structural loads?

Rivet nuts are excellent for attaching brackets, lights, and panels, but they are not designed for primary structural load-bearing in high-vibration environments. If you are building something that will hold significant weight, consider welding a threaded bung or backing plate instead.

Can I remove a rivet nut once it is installed?

Yes, but it isn’t easy. You usually have to drill out the head of the insert using a drill bit slightly larger than the body diameter. Be careful not to enlarge the hole in your base material too much when you do this.

Final Thoughts for Your Workshop

Mastering the use of rivet nuts is a rite of passage for any garage fabricator. They bridge the gap between “good enough” DIY work and a truly professional, finished result.

By keeping a variety of sizes and materials on hand, you’ll never be stuck trying to find a way to secure a bolt to a thin panel again. Start with a basic kit, practice on some scrap metal, and watch how quickly your project quality improves.

Remember to always wear your safety glasses when drilling and installing, and keep your workspace organized. Your next project is only one bolt away—get out there and make it happen!

Jim Boslice
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