Nuts are one of the most common types of threaded fasteners. They are typically used in conjunction with a bolt to join two or more parts. Nuts feature internal threading, whereas bolts feature external threading. After driving a bolt through the respective parts, you can secure the end of the bolt with a nut.
Nuts, however, are available in different styles. In addition to traditional threaded nuts with a square or hexagonal shape, there are barrel nuts. Barrel nuts are still used to fasten two or more parts together, but they feature a different design than their traditional counterparts.
Length
Barrel nuts are longer than traditional nuts. Most traditional nuts are relatively short. As shown in the photo above, they are typically less than one-quarter of an inch long. Barrel nuts, in comparison, are often over an inch long. Also known as dowel nuts, barrel nuts are longer, slug-like fasteners.
Threading
Perhaps the most notable difference between barrel nuts and traditional nuts is the threading. They both feature internal threading, which allows them to support a threaded bolt. Only barrel nuts, however, feature perpendicular threading. The threading in a barrel nut is continuous and runs perpendicular through the center.
Capped Ends
Another way in which barrel nuts differ from traditional nuts is a cap. Unlike traditional nuts, barrel nuts aren’t open on both ends. Instead, barrel nuts are capped. Both the top and bottom of barrel nuts are capped. The top featured a solid head with a slotted drive recess. Using a flat-head screwdriver, you can install barrel nuts in parts. Traditional nuts, on the other hand, are completely open. Traditional nuts feature a simpler design consisting of a treaded ring with an open top and bottom.
Aesthetics
Some people prefer barrel nuts over traditional nuts because of their aesthetically pleasing finish. Barrel nuts essentially conceal the end of the mating bolt with which they are used. As you drive a bolt through the center of a barrel nut, you’ll conceal it. Traditional nuts, in comparison, leave the end of the mating bolt exposed.
Applications
While they are both used to secure two or more parts, barrel nuts are used in different fastening applications than traditional nuts. Barrel nuts are particularly common in furniture and aerospace manufacturing. Furniture pieces use them as connectors, whereas airplanes and other types of aircraft use them in their landing gear and other components.