Hobson UNC Hex Bolt and Nut, 3/8" / 2"

The Hobson UNC hex bolt and nut range has 6 items (Grade 5 and Grade 8, zinc): 5/16", 3/8" and 5/8", in lengths of 1" to 2-1/4". Each item is a hex bolt supplied with a matching nut. Grade 5 is high tensile, and corresponds to metric class 8.8.

Grade 8 is high tensile, and corresponds to metric class 10.9. UNC means Unified National Coarse Thread and TPI means threads per inch. Spanner sizes are the width across flats (A/F), using its grade 5 and 8 column. Pack quantity is shown for each item.

Where this product is used

• Joining steel sections and brackets where a bolt and a matching nut are wanted in the one order line
• Fixing timber to steel through a drilled hole, with a flat washer under the head and the nut
• Interior frames and equipment where the part is kept out of the weather
• Medium-strength machinery and equipment work that needs more than Grade 2
• Heavy-duty assemblies and machine building where a high-strength fastener is wanted
• The 6 items cover diameters from 5/16" to 5/8" and lengths from 1" to 2-1/4", confirm the size against your drawing before ordering

Features

• 6 items: 5/16", 3/8" and 5/8", 1" to 2-1/4" long
• UNC thread, hex head
• Grade 5 and Grade 8, zinc
• Nut supplied with each bolt
• Minimum tensile strength for each size, shown for each size
• Zinc plated finish, for indoor and sheltered locations
• Grade 5 medium-carbon steel, quenched and tempered
• Heavy-duty Grade 8 alloy steel

Key specifications

Choosing the right option

Choose the thread form first: the bolt and its nut must match in thread form, diameter and pitch. Sizes are nominal diameters in inches; compare the threads per inch shown for each item with your nut. Length is measured from under the head to the end of the bolt, so choose size and length together. The nut is supplied with each bolt. Spanner size is the width across flats of the head and nut.

Zinc plating is a thin electroplated coating. It suits dry, indoor and sheltered work, and it does not meet treated-timber requirements, so zinc plated fasteners are not suitable for treated pine. For weather-exposed work, look at a hot dip galvanised version instead; within about 1 km of the sea, 316 stainless is generally the safer choice.

Grade 5 steel is medium-carbon and quenched and tempered. In the SAE J429 convention Grade 8 is alloy steel for heavy-duty use, shown by six radial lines on the head. UNC is the coarse inch thread, the general-purpose choice; it only mates with UNC nuts and tapped holes of the same diameter. For load-critical, structural or lifting joints, confirm the fastener against the engineer's specification. Fasteners are not lifting rated unless marked.

Related bolts: Hobson UNC Hex Bolt and Nut, Grade 8, Plain, 1/4" to 1-1/2" x 1/2" to 12", Hobson UNC Hex Bolt, Grade 5, Zinc, 1/4", 5/16" and 3/8" x 3/4" to 4-1/2" and Hobson UNC Hex Bolt, Grade 8, Zinc, 1/4" to 1" x 1/2" to 10".