Hobson UNF Hex Bolt, 1-14 / 3"

The Hobson UNF hex bolt range has 15 items (Grade 8, plain): 1"-14, in lengths of 2" to 9". A hex bolt has a hexagonal head and a threaded shank, and is fitted with a nut or screwed into a tapped hole. Grade 8 is high tensile, and corresponds to metric class 10.9.

UNF means Unified National Fine Thread and TPI means threads per inch. Spanner sizes are the width across flats (A/F), using its grade 5 and 8 column. All items are supplied as a box of 5.

Where this product is used

• Fabrication and repair work where the head can be reached with a spanner or socket
• Securing timber to steel brackets or flitch plates, with a flat washer under the head to protect the timber
• Trailer, rack and frame builds where a replaceable bolted joint is preferred to welding
• Assemblies that will be painted, oiled or enclosed after fitting
• Heavy-duty assemblies and machine building where a high-strength fastener is wanted
• Choosing between the 15 items here: they cover 1" diameter only and lengths from 2" to 9"

Features

• 15 items: 1"-14, 2" to 9" long
• UNF thread, hex head
• Grade 8, plain
• Minimum tensile strength for each size, shown for each size
• Plain finish: suited to dry indoor, oiled, painted or enclosed use
• Grade 8 alloy steel for heavy-duty work

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. Spanner size is the width across flats of the head and nut.

Plain steel carries no protective coating apart from a light oil film, which is why it rusts quickly if it gets wet. Keep plain parts for dry indoor use, machinery and assemblies that get painted, oiled or enclosed. Outdoors or in damp areas, a hot dip galvanised or 316 stainless alternative is the better choice.

In the SAE J429 convention Grade 8 is alloy steel for heavy-duty use, shown by six radial lines on the head. UNF is the fine inch thread: the finer pitch gives more threads per inch and a finer adjustment. It only mates with UNF 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 UNF Hex Bolt, Grade 8, Plain, 1/4" to 7/8" x 3/4" to 11", Hobson UNF Hex Bolt, Grade 8, Plain, 1/4" to 1-1/2" x 1/2" to 16" and Hobson UNF Hex Bolt, Grade 8, Zinc, 1/4" to 7/8" x 3/4" to 8".