Throughbolts

Throughbolts are fasteners designed to pass completely through the parts being joined and to be secured with a nut on the opposite side. This arrangement creates a strong, removable joint and is well suited to applications where access to both sides of the workpiece is possible. Throughbolts are commonly used in woodworking for furniture and cabinetry, in timber framing, and for mounting hardware or equipment to solid substrates where a nut can be tightened from the far side.

Types and materials vary. Common through bolts include hex-head through bolts, carriage bolts, and shoulder bolts. They are available in materials such as carbon steel and stainless steel, with finishes including zinc plating, black oxide, or weather-resistant coatings. The threads are typically UNC or metric, depending on regional standards. For high-load or outdoor use, stainless steel through bolts are often preferred to resist corrosion.

Installation considerations are important for performance. A clearance hole is drilled through the aligned parts, sometimes with a pilot hole in wood to prevent splitting. The through bolt is inserted from one side and secured with a washer and a nut on the opposite side, often using a second washer to distribute load. Locking methods such as lock nuts or thread-locking compounds may be used when vibration is a concern. It is important to ensure adequate edge distance and proper alignment to avoid crush or misalignment.

Advantages of throughbolts include strong clamping force, reliability, and easy removal or reassembly. Drawbacks include the need for access to both sides and potential material damage from overtightening or corrosion if incompatible metals are used. Throughbolts are a versatile choice for secure, detachable joints across a range of carpentry, metalwork, and light-structural applications.