Round Head Carriage Bolt

Round head carriage bolts are traditional fasteners specifically designed for use with wood and other soft materials. Their defining structure features a smooth, rounded head with an integrated square neck directly beneath it. The key advantage of these bolts is their combination of smooth, safe heads and the anti-rotation square neck, ensuring secure fastening in wooden substrates. Manufactured to ISO 8677 standards, the rounded head is smooth and safe, preventing injury or damage to the material. During installation, the square neck embeds into a pre-drilled hole or directly into the wood, preventing the bolt from spinning as the nut is tightened. With standard 6g machine threads, products provide a strong and reliable connection, ideal for soft materials.

Round head carriage bolts are widely used in wooden furniture, log home construction, wooden crates, outdoor wooden landscaping, and sheet material joining. In furniture making, they connect table legs, bed frames, and cabinets, combining safety with a classic aesthetic. For log homes, they secure beams and posts, ensuring structural integrity. In wooden crates, they provide strong yet removable fastening for transport and disassembly. For outdoor projects such as decking and pergolas, they withstand humid and wet conditions. When joining plywood or composite boards, they help prevent splitting. Products remain a core component in both traditional and modern woodworking.

These bolts are available in quality carbon steel 1020A, stainless steel 304, and hot-dip galvanized carbon steel. Carbon steel offers a 4.8 strength grade and is finished with zinc plating (ASTM B633) or copper plating (ASTM B766), providing basic corrosion protection with 48-hour salt spray resistance. Stainless steel 304 is ideal for outdoor and humid environments due to its excellent corrosion resistance. Hot-dip galvanized carbon steel provides superior protection, exceeding 120 hours of salt spray resistance. All round head carriage bolts are ISO 9001 certified, with square neck tolerances held to ±0.1 mm for consistent anti-rotation performance. Customization is available for extended lengths (up to 300 mm), special square neck sizes, heavy hot-dip galvanizing, and stainless steel options. Packaged in 50–100 pieces per specification with matching nuts and washers, they are convenient and ready for immediate use in your projects.