Below the head of a coach bolt (also known as a carriage bolt) is a square shoulder which is driven into the substrate by hammering the dome head. This prevents the bolt from rotating, allowing a nut to be tightened on the thread. Tightening up the nut at this point can also draw the square deeper into the substrate, ensuring that the head is well seated. The nut is often used in conjunction with a Form C or Form G washer, as the greater surface area of these washers (compared to Form A) spreads the load over a greater area, which is advantageous when working with soft materials, such as wood. Shop for A2 Stainless Steel Coach Bolts at Tradefix Direct. These 60mm M5 Coach Bolts are manufactured to DIN603. Stainless Steel Coach Bolts are perfect for wet or moist areas and also in oak timbers. Metric is the most common thread type in production today. Usually specified as M then a number x another number. This signifies the thread diameter and the length of the fastener. Often called carriage bolts or cup square hex bolts, coach bolts have a round head with a square underside.

Coach bolts are occasionally used in conjunction with shear nuts, which creates a strong, permanent fastening that is tamper-proof on both sides! In this application, it is advisable to use a standard hex nut to seat the carriage bolt head properly, and then remove it and install the shear nut.Unless you are using stainless shear nuts, install the shear nuts on the side of the application that will not be exposed to moisture or use corrosion protection paint to prevent rust from occurring at the shear point. If you have any questions about which types or sizes of carriage bolts you need, get in touch. A coach bolt, also known as a carriage bolt or cup square hex bolt, has a domed head, and the shank is topped by a short square section under the head. The square section grips into the part being fixed (typically wood), preventing the bolt from turning when the nut is tightened. For example M4 x 30 means that the major thread diameter (the external distance across the outside of the thread) is 4mm and the length is 30mm. Length is usually measured from the underside of the fastener head. Coach bolts are available in a range of sizes. All have metric coarse threads. They are most commonly used in the construction and timber trades.