Barrel Nuts

What are barrel nuts?

Barrel nuts are two-part fastening systems designed to securely join two materials together. Each assembly consists of a female barrel nut with an internal thread and a matching male screw that fastens into the barrel.

Barrel nuts are commonly referred to by several different names depending on the industry or application, including sex bolts, Chicago screws, inter screws, and binder screws. While the terminology varies, these names generally refer to the same style of fastening system. 

Unlike conventional nuts and bolts, barrel nuts provide a neat, low-profile appearance and can often be concealed within the material, making them suitable for applications where aesthetics are as important as fastening strength.

Why choose barrel nuts?

Barrel nuts offer several advantages over conventional nut-and-bolt assemblies, including:

• A clean, low-profile appearance
• The ability to conceal the fixing within the material
• Strong alignment between connected components
• Secure fastening for repeated assembly where applicable
• A wide choice of head styles to suit different installation requirements

They are commonly specified for furniture manufacture, architectural hardware, shopfitting, signage, display systems, engineering assemblies, and security applications.

Technical specifications 

Fastenright supplies barrel nuts in a wide range of specifications, including:

• Multiple metric thread sizes, most common including: M4, M5, M6, M8, M10, M12 and M16
• Various barrel diameters and lengths, with custom dimensions to order
• Truss, countersunk, raised countersunk, button, mushroom, hex, and other specialist head styles
• Steel, stainless steel, brass, and other material options
• A range of finishes to suit different environments and applications

When selecting a barrel nut, ensure the thread size matches the mating screw. The barrel should generally be slightly shorter than the total thickness of the materials being fastened.

Grip range should also be considered, as this determines the maximum material thickness the barrel nut and screw can securely clamp together.

How to measure barrel nuts

If you’re using a barrel nut outside of a pre-matched set, make sure the thread size of the nut matches your screw. The barrel should also be slightly shorter than the thickness of the material you’re fastening; this is measured from under the head to the end of the barrel.

Keep in mind that head styles affect how the length is measured:

• Countersunk heads: There are measured from the top of the head to the barrel’s end.
• Raised countersunk heads: These are measured from beneath the raised section to the barrel’s end.

Selecting the correct barrel length and grip range helps ensure proper installation and prevents over-threading of the mating screw.

How to install barrel nuts

To install a barrel nut: 

1. Drill a hole through the first piece of material for the barrel nut, making it slightly larger than the barrel’s outer diameter for a snug fit.
2. Drill a matching hole in the second piece to align with the nut.
3. Insert the screw or connector bolt through the second hole and tighten it into the barrel nut.

Some bolts come with a shoulder under the head, so factor that in during your setup.

Choosing the right barrel nut 

Different barrel nut designs are available to suit specific applications. 

• Phillips Oversized Truss Head: These are great for anti-vibration, thanks to the wide bearing surface and serrated underside.
• T Head Barrel Nuts: These barrel nuts offer extra strength with a rectangular head.
• Low Profile Socket Sex Bolts: These sex bolts are perfect for tight spaces and aesthetic applications
• Furniture Connector Caps and Bolts: These are made for furniture, but work well in panel assemblies too.

For applications requiring increased security, Fastenright also supplies tamper-resistant barrel nuts with drive types including Pin Hex, 6 Lobe Pin TX (Pin Torx), Clutch Head, and Wave Style. 

Need help?

Browse our full range of barrel nuts, sex bolts, Chicago screws, inter screws, and binder screws.

Alongside our standard range, Fastenright manufactures bespoke barrel nuts in non-standard sizes, materials, finishes, and configurations to support specialist engineering, manufacturing, architectural, and security applications.

If you require technical advice or a custom fastening solution, contact our team and we will be happy to help.