When shopping for bolts, you may come across hex bolts and carriage bolts. They are two of the most popular styles of bolts. Hex bolts and carriage bolts both feature exterior threading, and they are both used in conjunction with a nut to create a clamping force. Hex bolts and carriage bolts, however, differ in several ways.
What Are Hex Bolts?
Hex bolts are characterized by a hexagonal head. All bolts have a head. It’s the wide top section that provides a gripping surface for a wrench, socket or similar tool. Hex bolts are threaded fasteners with a six-sided head. You can find them in different sizes, materials, finishes and specifications, but they all have a six-sided head.
What Are Carriage Bolts?
Carriage bolts are defined by their dome head. They are still used to secure parts together via threading, but they don’t have the same six-sided head as hex bolts. Instead, carriage bolts have a raised, dome head.
Below their dome head is a square neck. As the name suggests, the square neck is shaped like a square with four sides. It’s designed to prevent the carriage bolt from rotating. When the carriage bolt is placed in a hole, the square neck will engage the adjacent material, allowing for a secure fit.
Differences Between Hex Bolts and Carriage Bolts
One of the biggest differences between hex bolts and carriage bolts is the head. Hex bolts have a flat six-sided head, whereas carriage bolts have a round mushroom-shaped head.
Because they have different head types, hex bolts and carriage bolts require different installation methods. Hex bolts are typically installed with a wrench or socket. Tools such as these can grip the bolt’s six-sided head. Carriage bolts, on the other hand,
Carriage bolts themselves aren’t directly tightened with a tool. After placing a carriage bolt through the hole, you can twist a nut onto the end of it. As you tighten the nut, the carriage bolt will become tighter. At the same time, the square neck will prevent the carriage bolt from rotating and coming loose.
Hex bolts and carriage bolts are used in different applications. Hex bolts are commonly used in machinery and structural applications. Carriage bolts, on the other hand, are often used in woodworking applications. The square neck allows carriage bolts to embed themselves in wooden holes. Hex bolts lack a square neck and, instead, feature a more traditional six-sided head.