Carriage Bolts vs Timber Bolts: What’s the Difference?

When most people think of fasteners, they envision bolts. Bolts feature external threading that attaches to external threading. You can secure two or more parts together by driving a bolt through them. To prevent the bolt from falling out, you can twist a nut onto it. While all bolts feature a shank with external threading, though, they are available in different styles, such as carriage and timber.

What Are Carriage Bolts?

Carriage bolts are threaded fasteners with a short mushroom-shaped head. They can be used in a variety of fastening applications. Also known as coach bolts, carriage bolts support metal-to-metal fastening as well as metal-to-wood fastening.

Carriage bolts have a partially threaded shank. Only about one-third of a typical carriage bolt’s shank is threaded. The remaining portion of the shank is smooth and unthreaded. With a partially threaded shank, carriage bolts have a better “grip” than fully threaded bolts.

What Are Timber Bolts?

Timber bolts are threaded fasteners with a slightly wider head. Like their carriage counterparts, they have a partially threaded shank. Some bolts have a fully threaded shank, meaning the cylindrical body is completely covered in external threading. But carriage and timber bolts have a partially threaded shank.

Timber bolts receive their namesake from their wood-to-wood applications. They are used almost exclusively in wood-to-wood fastening applications.

Differences Between Carriage and Timber Bolts

You can distinguish between carriage and timber bolts by inspecting the head. Carriage bolts have a short, shallow head that’s shaped like a mushroom. Timber bolts, on the other hand, have a slightly wider and fatter head.

Another difference between carriage and timber bolts involves the point of contact between the shank and the head. On carriage bolts, the head connects to the shank via a square-shaped section On timber bolts, the head connects to the shank via a set of four fillets. Timber bolts essentially have a washer built into them. Consisting of four fillets, this washer is located directly below the head.

Carriage and timber bolts are used in different applications. Of these two types of bolts, timber bolts are more versatile. You can use them in metal-to-metal fastening applications, and you can use them in metal-to-wood fastening applications. Carriage bolts, in comparison, are designed exclusively for wood-to-wood fastening applications.

In Conclusion

There are dozens of different types of bolts. While carriage bolts and timber bolts share some similar characteristics, they differ in several ways, such as their head design and intended applications.

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