There are many varieties of bolts, and the distinctions between them are not always obvious. In this article, we’ll go over the key differences between carriage bolts and lag bolts, which include the difference in shape, function, and size of each bolt type. While carriage bolts and lag bolts have quite a few similarities that make it easy to confuse them with one another, there are some key differences that may help you determine if you really need to use one type of bolt versus the other in your project at home or on the job site.
What are carriage bolts? Carriage bolts are fasteners used to secure a load or an object to a surface. The hex head carriage bolt and the square head carriage bolt are the two most common types of carriage bolts. The head of the hex head carriage bolt is hexagonal, while the head of the square head carriage bolt is square. Both types of bolts have threaded ends that can be tightened with a wrench. The shape of their heads is one way to tell the difference between these two types of bolts. If you can see part of the top surface, it is a hexagon-shaped carriage bolt. It is a square-headed carriage bolt if the top is completely hidden.
Lag bolts, also known as lag screws, are a type of threaded fastener that can be used with either wood or metal and feature a square or hexagonal head. They are commonly used to join two pieces by passing through the material from one side to the other. Unlike a carriage bolt, which requires being predrilled into the material before installation, lag bolts do not require pre-drilling. To tighten the nut of a lag bolt, simply turn it until it is as tight as you require. When tightening a carriage bolt, however, you must continue tightening after it has been fully tightened in order for the threads on either end of the bolt to catch and keep it secure. If you forget to do this, your carriage bolt will gradually loosen over time.
Carriage bolts are used to fasten two pieces of wood together. They are shorter in length and can be inserted from the top or bottom. Square head lags, on the other hand, are used to fasten metal plates together in steel structures. When tightened, the square head prevents rotation, making them more secure than carriage bolts. Lag bolts are your best bet for a general bolt that can be used in a variety of situations. Because they come with pre-drilled holes, they offer ease of use and installation. The downside is that their heads protrude from the surface, so they may need to be countersunk before installing if you want them flush with whatever surface they are installed into. Get the right size for the thickness of the material you’ll be attaching it to. One last thing to keep in mind is that most lag screws have straight slots while most carriages have angled slots.