Installing rivnuts in our van

What is a rivnut?

A rivnut is a strong loadbearing fastener. It works in a similar way to a rivet, however it is tubular and internally threaded allowing for the insertion of a bolt.

Rivnuts *[Also called a rivet nut or blind rivet nut]*

This is a great video that demonstrates how a rivnut works.

A rivnut is installed with a specialised rivnut tool, which compresses the fluted (malleable) part of the rivnut body to create a bead of compressed metal that pinches the install surface and securely attaches the rivnut.

Rivnuts are lauded for their strength and resistance to vibration after installation. They come in different body shapes, including a round rivnut (the most common), a hexagon rivnut (with good anti-slipping properties), and threaded studs (which as has protruding thread).

Rivnuts are often compared to plusnuts, but they are a little bit different.

The difference between a rivnut and a plusnut

A rivnut and a plusnut are similar, but there are a few differences.

Shape: The compressed bead of a rivnut a circular disc shape, whereas a plusnut compresses to the shape of a plus.
Size: A plusnut is bigger (longer and thicker) than a rivnut, being about double the size.
Tool: As a plusnut is bigger than a rivnut, a plusnut requires require a larger tool for installation. It also takes more effort to compress a plusnut because of its size.
Surface area: The plusnut has a larger surface area that pinches onto the install surface, which reportedly offers more grip.
Application: Rivnuts are more commonly used in light duty situations. Plusnuts are more robust are therefore more commonly used for their holding power in structural applications.
Cost: Plusnuts ($35AUD for 50x steel M6) are more expensive than rivnuts ($30AUD for 50x steel M6).

Apparently, plusnuts are more forgiving than rivnuts, and don’t require the same precision for the hole size and alignment (I don’t have any data to support that yet, just anecdotal evidence).

More info on rivnuts versus plusnuts here.

Plusnuts (left) versus rivnuts (right)

What are rivnuts used for?

Rivnuts are a simple solution for inserting a thread into a material that can’t hold a screw or bolt well. They are particularly useful when the install material is thin (as thin as 0.5mm), hollow (and therefore inaccessible from one side), or when the fastener access is limited. Perfect for a van!

Rivnuts were first used to attach a de-icer panel on the leading edge of aircraft wings. From aircraft, the use of rivnuts expanded to military and aerospace markets. Because of their many advantages, rivnuts soon entered general industry and have a wide range of uses today.

Common uses include:

Aviation
Automotive manufacturing
Electrical appliances
Kitchens
RVs and campervans
Trucks and trailers
Furniture
Bicycles
Medical equipment
Playgrounds
and much more

The Benefits of rivnuts:

There are many benefits of a rivnut.

Rivnuts:

Can be installed on one side (i.e., blind installation), so you don’t have to fiddle around trying to access to the rear end of the fastener.
Are strong and resilient, with high resistance to being pulled out of place.
Have excellent thread contact with the bolt, meaning rivnuts are able to join thin materials that otherwise don’t provide much grip for a conventional screw or bolt
Are able to connect two or more materials, including metal, plastic, fibreglass, and apparently ceramics (not quite sure how that one works!). But rivnuts apparently don’t work well in soft materials such as timber.
Give a professional finish
Require minimal training and are easy to install (theoretically)

Rivnuts are installed using a rivnut tool. A rivnut tool is a setting tool that produces the correct force tension to compress the fluted part of the rivnut body. It can be a manual tool, or power by battery or air. The manual tool is obviously the most cost effective, however the results are not as consistent and reliable as the other options.

How are rivnuts installed

What we used

M6 steel rivnuts
Hex head countersunk bolts
Rivnut tool + mandrel size options (we needed the M6 size)
Drill
Drill bits (8.9mm drill bit, hex head drive bit)
Safety gear (glasses, ear protection, mask)

Our process for installing rivnuts

Research

We made sure to dive deep into rivnuts, including watching videos, following guides, and chating to our rivnut supplier to ensure we installed them correctly. Despite this, it still didn’t always go smoothly.

Pre-drilling

We predrilled the holes in the ribs of the van ceiling.
We needed a 9mm hole for our M6 rivnuts. We were given an 8.9mm drill bit so we could get a snugger fit (apparently, this helps to prevent slipping).
After the hole was drilled, we painted it to protect the van from rust.
Tip: To make sure we didn’t drill through the van roof, we crafted a homemade drill bit stopper.

Safety is no joke — I actually got metal in my eye (even whilst wearing glasses), so gotta be careful

the rivnut tool

Next, we spun a rivnut onto the mandrel of the rivnut tool.
It is important to get the right tension in the rivnut. Too little and the rivnut won’t compress properly, too much at the nut can fail.

[We made this mistake, and didn’t compress the rivnut didn’t properly. We discovered the tool had loosened as we used it and it was no longer providing the force required to secure the rivnut. We spent a lot of time drilling out failed rivnuts. Very frustrating.]

Install the rivnut

We placed the rivnut into the pre-drilled holed
Using the tool (aiming to squeeze the arms of the tool with equal force in order to keep it straight and get it seated right), we installed the rivnut.

Checking the install

We removed the rivnut tool by spinning the handle on the tool
The result was an installed rivnut with a compressed bead on the blind side of the install surface, and an acccessible threaded insert for a bolt
As it was all new to us, we checked a few with a mirror to make sure it was installed right

[In some cases, this is how we discovered that we were in fact not installing them correctly and had to rejig the tool to make sure we got a better result]

Install boltS

We pre-drilled and countersunk the ceiling lining board so we were able to start installing the bolts.
The tricky part was lining the rivnut with the hole in the lining board (We actually ended up using a template to help with this (more on that here).
Rivnuts have a low tolerance to imprecision in this process. A tiny amount of resistance (usually caused by the timber sitting slightly off centre from the rivnut hole) could cause the rivnut to spin and fail. We learnt this the hard way and proceeded very carefully.

And it was job done.

Except when we stuffed up and a rivnut failed.

Keep reading for that.

Troubleshooting a failed rivnut

The biggest downside to using a rivnut is when it fails.

Which seemed to happen a bit too often for us, I guess because we were new to this (~7% failed).

We found there were two main situations when the rivnut failed: A spinning rivnut, or a poorly seated rivnut.

1. A spinning rivnut:

There is a low threshold (at least we found) for imprecision in the alignment of the rivnut and whatever was being installed.

If the resistance is above this threshold, the “hold” of the rivnut fails and it can start spinning.

It’s usually when the bolt is halfway or all the way in, so the bolt gets stuck. So, it’s a bit of a process to get it out in order to install another rivnut.

We learned a few ways to fix this situation.

Fixing a spinning rivnut

Step 1 is to get the bolt out:

Option 1: Drill out the bolt: We found at 10mm drill bit was the best for this. However, it took a lot of time and effort. We tried using a smaller drill bit and an extractor drill bit, but this didn’t really work.
Option 2: Drill out the wood: This was a quicker solution, however created an ugly hole in the timber that will need to be filled later on.
Option 3: Cut the head of the bolt off: This option also requires a bit of effort and a sharp hacksaw. But it meant we could remove the lining board and work on getting the bolt out with better visibility.

All the tools we used to TRY fix the rivnut — we found that drilling the bolt worked best

So, once the bolt was out, we needed to address the rivnut.

We tried a few things:

Option 1: Leave the failed rivnut in situ and drill another one: This is obviously the easiest option, but does not look the cleanest (although you can’t see it once the ceiling is installed).
Option 2: Drill out the rivnut: This can take a while and leaves a big hole in the rib of the van. However, it had to be done when the bolt was protruding and the lining board wouldn’t sit flush to the ceiling otherwise.
Option 3: Pull the rivnut out: This is not a great option because it warps the install surface and can be pretty damaging. We had to do it in a few situations because the other options didn’t work. It is possible, but would not recommend.

It’s not really possible to “fix” a spinning rivnut, but rather troubleshoot the situation in the best way possible in order to proceed with the build.

The other way we found that a rivnut can fail is when it sits at an angle. This makes it difficult to line up with the timber lining board, and if there is any resistance can cause the rivnut to start spinning (which needs troubleshooting in and of itself as above).

2. A poorly seated rivnut

Fixing a poorly seated is difficult and often doesn’t work. But we tried a few methods:

Option 1: Use the rivnut tool: When it is still screwed in, it’s possible to shift the poorly seated rivnut with the rivnut tool. But sometimes, the rivnut is just too angled or warped and this isn’t possible.
Option 2: Tap it back into place: We tried this with minimal success. We have seen other people use a hammer or similar, but it just doesn’t work well and can make the situation worse.
Option 3: Prevention: Prevention is the best remedy, because the other options just aren’t great.

Prevention

Preventing the issue from occuring in the first place is obviously the preferred option.

So, we found some strategies that helped to get the best chance of getting a successful rivnut:

Set the correct tension on the tool
Compress the rivnut equally by pushing the arms of the rivnut tool equally (otherwise the rivnut or even install material can warp).
Ensure precise alignment of the rivnut and install material
Before using the drill, screw the bolt in by hand. We used the drill just to get the final tension

Installing rivnuts in the Attie the Van

We had never used (or even heard of) a rivnut before the van build.

Rivnuts are a great option for a sturdy hold in a sheet of metal. But we had a few fail which was frustrating. And took a lot of time to troubleshoot.

The ceiling is installed now and it looks great (minus a few woopsies) and feels really solid.

But we would carefully consider the use of rivnuts in the next build!