M6 x 20 mm Cup Head Square Neck Bolt, 316 Stainless Steel - CHBA4M6X20

The Metric Cup Head Square Neck Bolt, 316 Stainless Steel is a domed (cup) head bolt with a square section under the head. The square neck seats in a square hole or bites into timber so the bolt does not turn while the nut is tightened. It is also called a carriage bolt.

Made from 316 (A4) stainless steel, the grade normally specified for chloride-exposed work such as coastal installations, swimming pools, marine fittings and food-processing plant. Metric sizes are written M followed by the nominal thread diameter in millimetres, so M10 is a 10 mm thread.

The range runs to 51 variants, covering sizes M6 to M16 and lengths 20 mm to 240 mm. Variants are supplied in packs of 10 to 100, depending on size.

In wet conditions, keep stainless steel apart from aluminium and galvanised steel with a washer or sleeve, to reduce the risk of galvanic corrosion.

Where this product is used

• Playground and outdoor furniture, where a smooth domed head faces out
• Small sizes for enclosures, instruments and light fittings
• Swimming pool and spa equipment
• Timber fencing, decking frames and pergolas
• Timber-to-timber and timber-to-steel connections
• Larger sizes for frames, plant and structural fixings

Features

• Smooth domed head with no tool recess to catch on
• Square neck locks into timber or a square hole
• Lengths from 20 mm to 240 mm
• A4 (316) stainless steel with molybdenum, for coastal and chloride-exposed settings
• Metric thread sizes match the nuts, bolts and tapped holes in most Australian-supplied equipment
• Choice of 51 sizes, M6 to M16

Key specifications

Selecting the right option

Drill the hole to the bolt diameter, then pull the square neck into the timber with the nut. Use a flat washer under the nut. The bolt length should cover the timber thickness plus the washer and nut with at least one thread showing.

Related products

Other versions in this range: Cup Head Square Neck Bolt M8 - 316 Stainless Steel. Often used with: Metric Standard Hex Nut - 316 Stainless Steel, Metric Hex Nylon Insert Lock Nut - 316 Stainless Steel and Flat Round Washer DIN125A Stainless Steel.