When are rivet nuts an ideal choice for an application? (2020)

https://fastenerengineering.com/when-are-rivet-nuts-an-ideal-choice-for-an-application/

by walterbell • 4 years ago

67 60 4 years ago

dieselgate3• 4 years ago

Wow cool article, didn’t know “fastener engineering” was a defined field. Was looking up snap buttons for canvas applications earlier (for boats etc) and there were more types than I was aware of. Buttons and rivets are rather cumbersome/manual to set but certainly have their advantages.

walterbell6• 4 years ago

A deeper dive on the same topic, https://info.baysupply.com/essential-guide-to-threaded-rivet...

rivets are rather cumbersome/manual to set

Astro ADN14 drill-adapter tool has polarized reviews, perhaps it works better with experience, https://www.amazon.com/Astro-Pneumatic-Tool-ADN14-Adapter/dp...

Kon-Peki• 4 years ago

Also the oldie-but-goodie, NASA Fastener Design Manual [1]. Rivnuts are on page 32, but not a lot of space is spent on them - they aren't strong enough for your rockets and satellites, although the military is willing to consider other types of blind rivets (page 94). Rivnuts look great to me, though!

[1] https://ntrs.nasa.gov/api/citations/19900009424/downloads/19...

jjeaff2• 4 years ago

Glue is another area that I'm sure has more than one specialty involved.

There are so many types of glue and factors like heat, flexibility, hardness, heat sensitive application, uv light drying, color, texture, time to dry, catalyst drying, and a million different types of materials that might need to be glued to another different type of material.

amalcon• 4 years ago

Obligatory reference to http://thistothat.com/. It doesn't cover every factor, but if you just want to quickly find an adhesive that will do a good job holding one thing to another, it's great. It also gives decent toxicity warnings.

gregschlom• 4 years ago

I use a simple formula: epoxy if I need strength, CA glue with activator for everything else.

(oh and wood glue for woodworking projects)

cuSetanta2• 4 years ago

Gluing in space applications is one of the very few areas I would consider myself close to an expert in (assuming I am not at the Peak of Mt. Stupid).

As you say, the number of factors involved is really crazy, especially when it comes to proving the suitability for a new glue. Thankfully there are a relatively small number of generally applicable glues that are used for 90% of situations.

For thos interested, the most commonly used glue in space in Europe is Scotchweld EC2216.

dzonga• 4 years ago

yeah, when I started utility woodworking i.e making a bed my old boss who dabbles in woodworking as a hobby told me forget nails. wood glue has more strength.

defterGoose• 4 years ago

Used to use these in architectural applications all the time. They definitely combine some of the best features of both rivets and threaded fasteners, but can be a little finicky to install correctly, just like regular rivets.

King-Aaron• 4 years ago

I love using rivnuts, I discovered them about a year ago and it's transformed the way I work on my car projects.

ambyra• 4 years ago

They’re great for hashtag vanlife stuff, like bolting cabinets to the frame.

tristor• 4 years ago

Man, I love rivnuts. These are great for bolting sheet metal onto a car in places it wasn't originally intended to go. I generally use them when building splitters, covers to flat bottom a car, or rear diffusers in addition to rods running into the frame. They're also great for simple repairs or for making alternate mounting locations.

One of my favorite tools is my rivnut gun.

Sophistifunk2• 4 years ago

Yup, they are a car-hacker's best friend, and once you've got the gadget you'll be surprised how often the solution to a random problem around the house turns out to be more rivnuts :)

bigiain• 4 years ago

“When the only tool you have is a nailgun, every problem looks like a messiah.”

throwaway0a5e4• 4 years ago

Only if you DGAF about your stuff being serviceable in the long term.

Rivnuts have the wonderful habit of going together like a bolt and coming apart like a rivet after only the slightest amount of corrosion gets applied.

That tiny interface between the rivet nut and sheet-metal is no match for the surface area of the threaded joint once there is corrosion involved. Sure you can help it out with good material selection and some anti-sieze but dealing with a spun riv nut is a little more twice as onerous as dealing with a rivet the normal way.

walterbell6• 4 years ago

Recent threads on fasteners: https://news.ycombinator.com/item?id=31956655 & https://news.ycombinator.com/item?id=31958512

mhb5• 4 years ago

Also: Lock Washers Don't Work

https://news.ycombinator.com/item?id=23584078

walterbell6• 4 years ago

Thanks, we need more DIY methods for quantitative evaluation of fasteners and joints, e.g. replication of this deck screw strength test, https://www.youtube.com/watch?v=eikOUFoIZ-Y

https://www.boltscience.com/pages/aboutus.htm

Bolt Science was founded in 1992 with the intention of becoming the recognised worldwide quality provider of independent technical expertise in bolted joint technology. Our clients include many of the major engineering organizations of the world. We provide analytical, testing, and technical problem solving services. We can help you understand the issues regarding the structural integrity of bolted joints and provide engineering solutions based upon our considerable experience in this field.

throwaway0a5e4• 4 years ago

If I was ever hiring for that kind of engineer repeating this drivel would get ones resume on the fast track to the circular filing cabinet because it indicates an inability to think critically about use cases outside of the box for whatever your definition of box is.

People have been mindlessly repeating that "split washers don't work" thing for decades but they're still around. Why? They're helpful for certain combinations of torque applied (low for the fastener size) and vibration (low but not none) that don't tend to apply in the high performance engineering that the internet fetishizes. If they were truly wasted money you wouldn't see them continuing to be used in many structural and consumer applications.

walterbell6• 4 years ago

Rivets are useful for custom plastic enclosures for electronic components, https://www.essentracomponents.com/en-us/news/guides/how-to-...

Plastic rivets are used in most things – from computers to panel fasteners in rockets. In most cases – not all – the rivet you use should have the same mechanical properties as the materials the rivets are intended to join. This means, for example, that plastic snap rivet fasteners can be used to join soft materials, such as other plastics, urethane and rubber.

HDPE and other plastic sheets are available online in various sizes, can be joined with rivets, rivnuts or plastic welding.

kazinator4• 4 years ago

None of those fasteners are rivet nuts, the submission topic.

Most of them cannot be installed blind; they require a mating piece on the other side to push into.

Rivet nuts don't require access to the opposite side. In all likelihood, they cannot be made of plastic; they depend on the the deformation of metal on the blind side forming a rigid bead which holds the part firmly place.

klodolph• 4 years ago

I was trying to imagine exactly how these work. Here's a video that shows them being used.

https://youtu.be/6D3oA_AvWh8?t=468

vishnugupta• 4 years ago

That’s exactly how number plate was fused to my car.

jmpman• 4 years ago

PEM studs are my favorite.

MarkMarine3• 4 years ago

Here we go, the professional has entered the comments.

The strength of PEM nuts is so much better than rivnuts. I designed parts for a missle system that had to be transported, and possibly air dropped, and rivnuts were not going to work when you have to handle 20g.

Gibbon1• 4 years ago

Used to use PEM nuts for mounting industrial controls onto panels.

formerly_proven• 4 years ago

I had to knock a few of these out of sheet-metal case and man I did not expect that kind of resistance from something with such a tiny contact area in 0.8 mm sheet metal.

amelius• 4 years ago

But it seems you need a tool that can apply a force from two sides of the plate. This is not easy if the plate is large and the hole is in the middle.

rootw0rm• 4 years ago

Here's a pretty cool video I found on the subject:

https://www.youtube.com/watch?v=C3eBtuGlqSo

londons_explore• 4 years ago

Isn't a far simpler solution to use a big hammer? I assume the momentary force from a hammer is tens of thousands of lbs?

djfobbz2• 4 years ago

For most applications, I prefer PEM over Rivet Nuts but sometimes Hex Rivet Nuts do the magic better! For PEMs, we use Haeger 824 Plus insertion press.

back7co• 4 years ago

I've moved from 3D printed designs like the Recovery Kit over to laser cut metal and rivnuts. I love them.

rainbowzootsuit• 4 years ago

The article also equally applies to the unmentioned outie version of rivnuts, the rivet stud.

https://www.mcmaster.com/Rivet-Studs

sly010• 4 years ago

One issue with them, (specifically the crossnut variety) is if you don't use the correct tool a crossnut might start spinning in the metal. If that ever happens when your final bolt is already in, it's like having a nut on the blind side. You can't unscrew the bolt. Otherwise they are great, just but the right settings tool and drill the right size hole.

kazinator4• 4 years ago

Rivet nuts have sections that perform a different job and must be optimized separately. The part of the rivet which deforms to form a bead must be relatively soft metal; but the threads have to be hard.

Like with anything, I'd expect the rivet nut market to be flooded with fake overseas junk that is soft all over, such that the threads strip if you look at them wrong.

When are rivet nuts an ideal choice for an application? (2020)

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