These bolts got their name for the original purpose. Carriage bolts were used in a carriage which was the basic transportation during olden times. The wheels of the carriage are made of wood. It was in 1818 at Connecticut when a blacksmith named Mr. Micah Rugg invented a machine that will produce these special bolts. Rugg and Barnes is the first company in America that produces bolts and nuts. Carriage bolts or plow bolts are type of fastener that is commonly used in carpentry and construction of wood products like furniture, wooden picnic table, wood garage doors and wood crafts. They are used in smooth and flat surface because of its aesthetic appeal that adds to the finished look of the wood surface. Carriage bolts are not limited to wood products; it can also be used in metal products, you just need to take some consideration in fastening two pieces of metals.
Carriage bolt heads are domed shaped and under the head is a square shaped neck. It may also be available in angular, flat or domed top and no neck. The square section part of the bolt is for gripping purposes, so it will not move or turn when you spin the nut. Carriage bolts are designed to have a secure fit so it will be safe and reliable. The common bolt types are zinc-plated bolts, steel grade 5 bolts, stainless steel 18-8 bolts, silicone bronze bolts and hot dipped galvanized bolts.
There are many different varieties of diameters, sizes, styles, types and grades of steel. The common grades of strength are grade 3, 5 and 8. The bolts diameter may range from 3/16 to 3/4 inch and 1/2 inch to 10 inches when it comes to length. There are seven categories in carriage bolts measurement and these are square depth, square width, screw length, head height and head diameter. The body diameter refers to the unthreaded part; it is between the square neck and the thread part. The square width is the total measurement of the square neck. The square depth refers to the square neck of the bolt but other bolts do not have a square neck. The head diameter is the width of the bolt’s head. The bolt length is the distance from the bottom of the bolt’s head up to the tip of the bolt.
Carriage bolts are not intended to be driven and you need to insert the bolts in a pre-drilled hole. So there is no need to use a tool to screw it. They are used to fasten or tighten two pieces of objects. It may look so small and useless but the truth is, it is very essential and beneficial in our everyday life. The carriage bolt can holds and supports objects that we normally see and use like furniture, cars, bridges and railways. If you need carriage bolts, you can buy this in any hardware store or even online store.