Coach Bolts vs Other Bolts: Which One Should You Choose?

Are you considering using coach bolts (also known as carriage bolts) for your next project? DIN 603 coach bolts are a popular choice due to their simple design, ease of installation, and reliable performance.

But how do they compare to other types of fasteners? In this article, we'll examine the different characteristics of coach bolts so that you can make an informed decision about which type of fastener is best for your application.

We'll also look at some alternatives to carriage bolts that may be better suited for certain projects. 

Types of Fasteners

With so many types of fasteners available, it can be overwhelming to decide what you need. But don't worry, we've got you covered! From coach bolts to machine screws and set screws, we have the expertise and experience to help you choose the best option for your application.

Coach Bolts

Coach bolts, also known as carriage bolts, are commonly used in carpentry applications due to their strong construction and relatively low cost. They are typically made from steel with a zinc plating or from stainless steel for higher corrosion resistance.

Coach bolts have been around in some form since the 19th century, and were originally used in the construction of horse carriages, hence the name! Around a similar time, coach screws began to be used for a similar purpose, but more so to connect pieces of timber with their coarse thread.

Coach Screws

DIN 571 coach screws feature a hex head and come with an unthreaded shank at longer sizes to increase their weight-bearing capacity. They are designed to be used with primarily with wood rather than metal components, and are sometimes confused with coach bolts.

Hexagon Bolts

Hex bolts have hexagonal heads and part-threaded shafts to increase their load-bearing capacity. M20 hex bolts DIN 931 are generally preferred to the full threaded variety due to them being used in heavier duty applications that require maximum resistance to pressure.

Fully Threaded Bolts (Hexagon Set Screws)

DIN 933 fully threaded bolts (hexagon set screws) feature large threads that extend all the way down the length of the bolt for extra holding strength and to provide additional versatility than DIN 931 bolts due to being able to fasten with a nut all the way to the head.

When choosing which type of fastener is best suited for your needs, consider factors such as environment, size requirements, material composition, load capacity and security features. 

Lets talk a bit more about the advantages and disadvantages of coach bolts now.

Advantages of Carriage Bolts

Making the right choice for your fastening needs can be tough, but coach bolts are an ever-popular choice. Coach bolts, also known as cup square carriage bolts, are threaded fasteners with an external male thread that is secured with a matching pre-formed female threaded nut.

They have many advantages over other types of fasteners and are ideal for applications where aesthetics are important due to their mushroom head, which provide a flush finish to the surface of the timber or metal that they secure.

Carriage bolts provide great gripping strength and security due to their large head diameter and deep undercut. The square cup under the bolt head is designed to prevent the bolt from turning when it's tightened, allowing for easy installation and removal without any special tools or equipment.

They also come in various finishes such as zinc-plating, brushed, or stainless steel, which give them different aesthetics and properties depending on their requirements. M12 coach bolts in stainless steel are suitable for use in exposed areas due to their corrosion resistance, and are one of the most popular sizes available.

There are a wide range of sizes available in both metric and imperial units, so you can choose the right size for your application.

Disadvantages of Carriage Bolts

Although carriage bolts offer many advantages, they also have some drawbacks that should be considered when selecting a fastener.

A disadvantage of carriage bolts is their limited range of sizes and materials. While they are available in sizes from M6 to M16 coach bolts, and in steel, stainless steel, brass, bronze, and nylon materials, other types of bolts offer more choices.

For example, machine screws come in smaller sizes than most other fasteners, while grub screws can be used without nuts.

Another disadvantage is that carriage bolts may not always provide an aesthetic solution for projects where appearance matters; some other bolt head shapes such as hex or square may better suit certain applications to provide a more rustic look.

Similarly, security features can often be more easily implemented with other types of bolts such as snake-eye and scroll bolts which require specialist tools to install and undo, making them less susceptible to tampering. It is important to consider all options before deciding on a suitable bolt for your project.

Alternatives to Carriage Bolts

While there are many possible alternatives to coach bolts, there are only really one or two that do the same job, just without the same head. Hex bolts are the most common alternative, They come in a wider variety of sizes and materials, but have their own advantages and disadvantages. 

Carriage/Coach Bolts vs Hex Bolts

Choosing between a carriage bolt and a hex bolt can be difficult, but if security is an issue, carriage bolts could be a better choice because they offer increased security due to their mushroom head.

Coach bolts also provide better stability when fastening with a nut, and are more resistant to tampering due to their head shape. They are similar to DIN 931 hex bolts in the sense that at longer sizes they feature a shank for additional strength.

DIN 933 set screws, such as 14mm fully threaded bolts, offer an alternative solution to hex bolts due to them being fully threaded, which can increase their versatility, albeit while sacrificing some load-bearing capacity.  

If you need reliable fasteners that will stand up to any challenge, then coach bolts could be a good option.

At Fixabolt, we have a wide range of carriage bolts available, including M10 stainless steel coach bolts. Shop our full range with free delivery over £50 and quantity discounts.