Galvanized Carriage Bolts
Carriage bolts, or coach bolts are heavy-duty bolts with a square or hex head that are used to join metal and wood together. Primarily used in large construction projects, The beauty of using a carriage bolt is that is that the threads literally bit right through the wood creating a tight connection - that’s why a wrench or pliers are required to turn them. For added security use washers and threadlockers to keep bolts securely in place.
Carriage bolts are used to fasten wood to wood, wood to metal and metal to metal. They are a member of the round head bolt family and commonly have a "circular head with a low rounded top surface and flat bearing surface, and an integrally formed square neck under the head." Found on chain link fences and often on patio furniture and swing sets made of wood, carriage bolts are also known as: carriage screws, round head square neck bolts, coach bolts; shaker screen bolts (when fully threaded). Since the head is designed not to turn, they are usually tightened by torquing a nut. However, they can be used with an internally threaded (tapped) hole and tightened by turning the carriage bolt's square neck, if accessible.
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