Bolt vs Setscrew: Understanding the Difference
Avoiding common fastener mix-ups with our quick and simple guide.
We often hear customers ask:
“Can I get a bolt, full thread?”
Our response: “Do you mean a setscrew?”
“No, a bolt… full thread.”
We get it. These terms sound interchangeable—but in our world, they mean very specific things. And if you’re ordering fasteners for a job, it pays to know the difference.
Let’s break it down.
What is a Bolt?
A bolt is a type of threaded fastener, typically with a partially threaded shank. That means part of the body is unthreaded, and it’s designed to be used with a nut to clamp two or more components together.
Key features of a bolt:
Threaded only part of the way up the shank
Usually used with a nut
Designed to clamp two parts together
Often inserted through pre-drilled holes
Think of bolts as the go-to when you’re securing materials with a nut on the other side.
What is a Setscrew?
A setscrew (also known as a cap screw) is a fully threaded fastener—the threads run right up to the underside of the head. It’s typically used without a nut and is often screwed directly into a tapped hole.
Key features of a setscrew:
Fully threaded from tip to head
Usually used without a nut
Often screws into a tapped hole
Can also be used to prevent movement between two parts
Setscrews are often used in machinery or assemblies where components need to stay fixed in place under vibration or motion.
Why the confusion?
The terms “bolt” and “setscrew” are sometimes used interchangeably in the trade, and to be fair, the differences can be subtle if you’re not handling them every day.
That’s why we’re starting this blog series - to share the basics in plain English, and help you get exactly what you need, first time.