Forgefix Carriage Bolt & Nut - M8 x 65mm - White

Zinc plating provides a protective layer against rust and corrosion, significantly enhancing the bolt's durability and lifespan, especially in outdoor or moderately damp conditions. It acts as a sacrificial coating, corroding before the steel bolt underneath.

The square section is a key design feature. It's designed to embed into the timber once the bolt is inserted and tapped into place. This prevents the bolt from rotating when you tighten the nut from the opposite side, allowing for easier, often one-person installation with a single wrench.

While primarily designed for timber-to-timber applications due to the square neck's need to embed, they can potentially be used to fasten timber to certain composite materials or even thin metal sheets if the non-timber material can accommodate the square neck or if anti-rotation isn't critical for that specific joint.

You will need a power drill with an appropriate sized drill bit (e.g., 8.5mm or 9mm for an M8 bolt) for pre-drilling holes. For tightening the hex nut, a wrench or spanner of the correct size (typically 13mm for an M8 nut) will be required. A rubber mallet can be helpful for seating the bolt head.

'M8' refers to the bolt's nominal diameter, which is 8 millimeters. '65mm' refers to the bolt's length, measured from directly under the head to the tip of the threaded end. This measurement helps ensure you choose the correct bolt length for the thickness of the materials you are joining.

While zinc plating offers good corrosion resistance for general outdoor use, for highly corrosive environments such as direct saltwater exposure or marine applications, a more resistant material like stainless steel (e.g., A4/316 grade) would typically be recommended for superior long-term performance and durability.

DIN stands for 'Deutsches Institut für Normung' (German Institute for Standardization). DIN 603 specifies the dimensions, materials, and other characteristics for carriage bolts. DIN 934 does the same for hex nuts. Conformance to these standards ensures the bolts and nuts meet specific quality, dimension, and performance criteria, ensuring interchangeability and reliability.

This indicates the square section under the head has not fully embedded into the timber. Remove the nut, reposition the bolt, and gently tap the head with a hammer or mallet to ensure the square shoulder properly bites into the wood. Ensure the pre-drilled hole is not too large.

Verify that your drill bit size is appropriate for an M8 bolt (e.g., 8.5mm or 9mm). Check for any obstructions or debris in the holes. If the timber is very dense, a slightly larger drill bit might be needed, but be cautious not to make the hole too wide for the square neck.

This can happen if the timber is too brittle or the hole is too tight for the square section. Try pre-drilling a slightly larger diameter for the square part of the bolt (just a few millimeters deep) or use less force when tapping the bolt head. Consider using a washer under the bolt head if the timber is prone to splitting.

Check for cross-threading by unthreading the nut and attempting to re-thread it carefully. Ensure the bolt's threads are clean and undamaged. If the threads are damaged, replace the bolt and nut. Ensure you are using the correct M8 nut for an M8 bolt.

Ensure the timber sections are firmly pressed together before tightening. Over time, timber can shrink slightly, causing joints to loosen. Re-tighten the nut as needed. If the timber itself is compressing or deforming, consider adding washers under the nut or using larger bearing plates.