Acorn Cap Nuts
Hex Nuts with a Domed Top to Cover Exposed Threading
Acorn nuts are a type of fastener whose name comes from its shape. It is a hex nut with a closed-end, domed top to cover the exposed threaded end. Acorn nuts are easily removed for maintenance to be performed. They also provide an aesthetically pleasing finished look. Acorn Nuts are available in 304/18-8 Stainless Steel, 316 Stainless Steel, Brass, Chrome Plated, and Nickel Plated finish.
High Crown Acorn Nuts
High Crown Acorn Nuts are Cap Nuts with an extended domed top to receive a longer threaded portion of a screw, bolt, or other threaded fasteners. This creates a deeper thread depth and higher dome for aesthetic and practical benefits.
Extra Tall Acorn Nuts
Extra Tall Acorn Nuts (also called Extra Tall Acorn Nuts or Extra Tall Cap Nuts) are precisely what they sound like. They are standard cap nuts with a significantly increased height. This added height allows for a greater internal thread depth, which means that more of a bolt or machine screw can be inserted into the nut. Many Applications use this feature for both practical and finish reasons to keep the bolt or screw thread within the cap nut.
Extra Tall Cap Nuts come in either a rounded or domed top and a flat-top design. All Extra Tall Acorn Nuts are available in 18-8 Stainless Steel and are USA made.
Need help choosing a material? Check out our material guide to help you with all your fastener needs.
All About Cap Nuts: High Crown, Too Tall, & Standard Nuts
All About Cap Nuts Transcript
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Bob: Welcome back to Albany County Fasteners, Fasteners 101. I'm Bob and today we're going to discuss high crown and too tall cap nuts. So let's get started.
I have cap nuts here. I have a standard cap nut that you'll find almost anywhere. I have what they call a high crown and you can see, the crown's a little higher. It's probably somewhere about, I would say about, a heavy 3/8 of an inch taller than a standard cap nut. Then we have too tall. We have a too tall in a flat head and we have too tall in a rounded head.
Now the two tall come fully threaded all the way through the inside to the top. So you have full threads all the way through. You have on the too tall what they call a flat top. You can see the top is flat and it has a chamfered edge around it and on the round the top is just rounded over like the standard cap nut at the top.
They call these too tool because they're approximately, if you took the highcrowns, double the height almost. But if you had two high crowns, I don't have two high crowns here but if I did, it would be close to this size and that's why they call it a too tall.
These are USA made products, they're made here in the USA. They're quality products. These are 18-8 stainless steel. They're available on our shelf ready to ship.
The question always comes up "what do I use for different things"? Depends on your application. So many different applications out there. How far is your threaded bolt sticking out on the other end? If it was sticking out that much, you couldn't use a standard cap nut. You're going to see probably about a 1/4" - 3/8" of an inch sticking out. If that was the application. So, then you would go to the high crown.
I'll just keep my finger there as a stop, and that just makes it. Those are the different applications. This one, which is double tall, will keep on going and, just so you know, you will get some gulling because the difference here with stainless steel is that you have a rolled thread on the bolt and on the actual cap nut you have cut threads. So you have two different threads running against each other which creates gulling. You can use some lubricant. That works well.
I just want to show you on this how far this will go in. So you're looking at a good 1-1/2" of this 2" bolt, that I have here. It'll go all the way in to this cap nut and there it is.
As far as applications go, there are many different applications. I've seen these used for - they get polished up - some people will take them and polish them up. Polished stainless is amazing - the way it looks. They'll take them and put them on their trucks and their cars just for the look. It's all dependent on application.
Here at my packaging machine, I want to demonstrate to you how they incorporated a cap nut. This is a standard cap nut. This is the bowl where the fasteners go in. This is a feeder and they used a cap nut, at the top, along with a lock washer to hold this cone in place so the fasteners don't build up up and around the center of the machine. Here they used a standard cap nut with a lock washer to hold this cone in place.
You could also, in this application, use any of them. Here's a high crown, that works on there, and here's a double tall. You can use that on there. This is actually a lot easier because sometimes the small little fasteners that we put in this machine, they get underneath this cone a little bit. They jam under there and you have to take this off. That's why they they make it so you can screw it off with your fingers. I just used the top round one.
That's pretty cool looking, but functionally it doesn't matter. The standard that comes with the machine, you can see here, the standard cap nut, finishes it off nice. Nothing can build on top during fastener jobs.
Little fasteners, like a two point five millimeter falling on top won't stay on top of this nut. It just falls off and that's just the design. I just wanted to show you on my packaging machine how that could be applied.
What is a cap nut used for?
Acorn Cap Nuts are used to cover the exposed threading of threaded rods or studs and bolt ends. This is done for safety reasons and to provide a clean, finished look to the application.
How do you remove a cap nut?
Removing a cap nut is simple. They're threaded the same way as traditional hex nuts, so they can be removed with traditional pliers, wrenches, or ratchets that fit snugly around the nut.
How do you install a cap nut?
Same as other hexagonal nuts: with a wrench, pliers, or a ratchet. Cap nuts are just hex nuts with a dome over one side of the internally threaded hole, enclosing it.