Ever tried to put threads into thin metal when you can only reach one side? That’s where rivet nuts come in handy. They’re these clever little fasteners that create strong, reusable threads from just one side of your workpiece.
You might see them called RIVNUT®, Nutsert®, or other brand names, but they all work the same way: you install them from one side, and a tool collapses the back end to lock everything in place. Pretty neat, right?
Picking the Right Rivet Nut
Before you start drilling holes, you need to choose the right insert. Here’s what matters:
Material matters. Aluminum ones are lightweight and easy to install – perfect for most jobs. Steel gives you more strength when you need it. And if you’re dealing with harsh environments or corrosion, go with 316 stainless steel.
Body style makes a difference too. Hard materials and tight holes call for a smooth, rounded body to get the job done right. But if you’re working with soft materials or worried about the insert spinning in the hole, knurled or hex bodies grip much better.
Head style depends on your application. Need it flush? Go countersunk. Working with soft material or oversized holes? Large flange heads spread the load. For most jobs, the small/low profile heads work just fine.
The grip range is crucial – that’s the thickness of material the rivet nut can handle. Your material thickness absolutely must fall within this range, or you’ll have problems.
Getting the Hole Size Right
This is a common pitfall. Too small and you’ll buckle the insert. Too large and it’ll spin in the hole. Here are the common sizes:
For metric threads:
- M4 needs about 5.8-6.0mm
- M5 needs 6.8-7.0mm
- M6 needs 8.9-9.0mm
- M8 needs 11.0-11.1mm
For imperial, a 1/4-20 thread typically needs a 0.375" (9.53mm) hole.
Don’t forget to check your manufacturer’s documents, things like hex bodies and heavy-duty types can change the rules.
Tools You Can Use
You’ve got options here. Hand tools are perfect for small jobs. They’re basically a mandrel and nosepiece matched to your thread size.
For production work, air tools are the way to go. Fastener tools clinch the nut to collapse the rivet nut, then reverse to release. “Spin-pull” tools thread in, then pull to set – they give you better control for consistent results.
Actually, Installing the Thing
Step 1: Measure your material thickness and pick a rivet nut with the right grip range.
Step 2: Drill your hole to the exact size specified. Clean out any burrs or chips.
Step 3: You will want to set up your tool with the right mandrel and nose for your specific thread size.
Step 4: Thread the rivet nut onto the mandrel until it seats against the nose – usually just 1-3 turns.
Step 5: Put the rivet nut flush in the hole and trigger your tool. The back end should collapse and clamp firmly behind the material.
Step 6: Reverse to unthread the mandrel. You’re done.
Quick Quality Check
Thread a bolt in and give it some torque. The insert shouldn’t spin in the hole before the screw reaches normal clamp load. The head should sit flush with no gaps, and the threads should accept full engagement.
When Things Go Wrong
Insert spins in the hole? Your hole might be oversized, or you need a knurled or hex body for better grip.
Loose, wobbly insert? You didn’t collapse it enough. Increase your tool’s stroke or force setting.
Cracked head or buckled body? You over-crimped it. Reduce force and double-check your hole size and material thickness.
Real Example: M6 in 2mm Steel Sheet
Let’s say you need an M6 thread in a 2mm steel sheet:
- Choose an M6 steel rivet nut that has a grip range that includes 2mm
- Drill a 9.0mm hole and clean it up
- Set up your tool with the M6 mandrel
- Install the rivet nut and do a quick torque check
- You’re ready to go
The Bottom Line
Installing rivet nuts isn’t rocket science, but getting it right comes down to the details: right hole size, staying within the grip range, and doing a quick quality check when you’re done. Get those three things right, and you’ll have strong, reliable threads that’ll last.
These little fasteners are incredibly useful once you get the hang of them. Whether you’re mounting accessories on vehicle panels, working with composite materials, or just need threads where you can’t reach the back side, rivet nuts are often the perfect solution.