Fastener DIN 603/934 Cup Square Bolt Or Carriage Bolt And Nut

Important Installation Notice

• Oversized square hole: The square neck will slip, anti-turn function fails, the bolt rotates along with nut and cannot be fully tightened.
• Undersized square hole: The bolt cannot be pressed into the plate smoothly.

  Please confirm the square neck dimension before machining holes to achieve reliable connection.

Common Application Scenarios：

• Steel Guardrail Structures: Road guardrails, fences, railings, and bridge safety barriers.

• Warehousing and Logistics: Warehouse racking, steel platforms, and shelving assembly.

• Outdoor Wooden Structures: Log cabins, pressure-treated wood boardwalks, and outdoor wooden components for landscaping.

• Furniture and Equipment: Metal furniture, fitness equipment, and frames for agricultural machinery.

• Vehicles and Trailers: Trailers, truck side panels, and agricultural vehicle body assembly.

FAQ:

Q1: What is a carriage bolt?

A: A carriage bolt is a fastener with a smooth round domed head and a square neck under the head. The square neck locks into material to prevent spinning when tightening the nut, widely used for wood, deck and furniture assembly.

Q2: What length carriage bolts bolts for 4×4 posts?

A: 6-inch to 8-inch carriage bolts (commonly 1/2″ x 6″ or 1/2″ x 8″ depending on whether you double up the rim joists)

Q3: How to remove carriage bolts?

A: Carriage bolts feature a square neck to prevent rotation. To remove it, hold the square shoulder, unscrew the nut counterclockwise, then knock the bolt head out from the hole.

Q4: How to use carriage bolts?

A: Carriage bolts come with round domed head and square neck. Insert the bolt into pre-drilled hole, embed square neck into workpiece, then attach washer and nut and tighten for stable connection.

Q5: How to tighten a carriage bolt?

A:A carriage bolt has a square neck to stop rotation. Embed the square shoulder into the workpiece, place washer and nut on the shank, then turn the nut clockwise with a wrench to tighten the carriage bolt.

Q6:What size carriage bolts for deck?

A:Choose carriage bolts for deck according to wood thickness. Common sizes are 5/16″or 3/8″ diameter, length long enough to pass through deck boards and supporting joists, leaving enough thread for washer and nut.