If you have ever looked for a strong bolt for a project, you have likely seen carriage bolts. But, is a carriage bolt a suitable fastener for your project? In this article, you’ll learn all you need to know.
How To Choose The Right Carriage Bolt For A Project
The most important considerations when purchasing carriage bolts is the material you are securing and the environment the bolts will be in. Keep in mind that the square neck will take up part of the shank length when determining the size you require.
If the application is outdoors, choose either HDG carriage bolts or stainless steel carriage bolts, as these offer the best longevity and strength when exposed to the elements.
You will also want to consider the head of the carriage bolt. There is a flush-fitting style of carriage bolt known as the plow bolt. These are most often used in wood applications, and the heads are countersunk into the wood.
What Is A Carriage Bolt?
Carriage bolts, also called round-head square-neck bolts or coach bolts, are usually used to fasten metal to wood or metal to metal. There are numerous types available:
– Galvanized Carriage Bolts
– HDG Carriage Bolts (hot dipped galvanized)
– Stainless Carriage Bolts
– Zinc Carriage Bolts
What Does A Carriage Bolt Look Like?
Carriage bolts can be differentiated from other types by their rounded mushroom-like, shallow-domed heads. While the shank is primarily round, unlike other bolts, it is square beneath the head and does not have threads spanning the entire length. Its diameter is the same as the square, which allows the bolt to be installed with one tool and makes it self-locking.
When To Use A Carriage Bolt
Carriage bolts were initially designed for fastening iron plates to either side of wooden beams, as the square portion of the bolt fit into the hole in the iron, which was also square. These bolts got their unique moniker because they were often used in making horse-drawn carriages.
Today, carriage bolts are often employed in locks, hinges, and other security fittings, as their shape prevents unlocking from the insecure side of the bolt. Other industries that frequently use carriage bolts are farming, mining, railroad, and water conservation and treatment.
Homeowners and do-it-yourself types like carriage bolts due to their strength and aesthetic appeal. Some popular uses are for decks, fencing, and backyard playsets.
How To Use A Carriage Bolt
Because of the unique shape of carriage bolts, you should only insert them into pre-existing holes. The rounded, smooth head does not allow for the use of a drill or screwdriver. However, you want to be sure you have the corresponding washer and nut to secure the bolt.
If your material is not pre-drilled, use a drill with the appropriate sized bit to drill a hole the size of the bolt. Put the bolt in the spot you created, attach the washer first, then the nut to the opposite side. Some people want to skip the washers, but these are important to prevent damage when securing the nut, as tightening it pulls the bolt against the material being fastened. Both the bolt head and washer/nut combo should be flush against the opposite sides of the material.
How To Remove Carriage Bolts
There may come a time when you need to remove a carriage bolt. In this case, twist the nut. If it is stuck, you can loosen it by holding it with locknut pliers while tapping on them with a hammer.
