Hobson UNC Hex Bolt, 5/16" / 4 1/2"

The Hobson UNC hex bolt range has 45 items in grade 5, plain finish: sizes 1/4" to 7/16", with lengths from 3/4" to 6". Grade 5 is high tensile, and corresponds to metric class 8.8. UNC means Unified National Coarse Thread and TPI means threads per inch.

Where this product is used

• Screwing into a tapped hole in a casting, plate or housing where there is no room for a nut
• Fabrication and repair work where the head can be reached with a spanner or socket
• Replacing worn or missing bolts of the same thread form, diameter and length
• Workshop jobs where the part is protected by its surroundings
• Medium-strength machinery and equipment work that needs more than Grade 2

Features

• 4 sizes: 1/4" to 7/16"
• Grade 5, Plain finish
• Lengths from 3/4" to 6"
• Pack quantity and part number for every item
• Proof load and minimum tensile strength
• Spanner size (A/F) by size
• Plain (uncoated) steel for dry indoor and machinery use
• Grade 5, medium-carbon quenched and tempered steel

Key specifications

Choosing the right option

Choose the thread form first: the nut must match the bolt in thread form, diameter and pitch. Length is measured from under the head to the end of the bolt. For a bolt and nut set: see Hobson UNC Hex Bolt and Nut, Grade 5, Plain, 1/4" x 3", Pack of 150.

Plain (uncoated) steel has no corrosion protection beyond a light oil film, and it rusts quickly once moisture reaches it. It suits dry indoor jobs, machinery, and assemblies that will be painted, oiled or enclosed. Where the job is outside or damp, move to hot dip galvanised or 316 stainless.

Grade 5 steel is medium-carbon and quenched and tempered. UNC is the coarse inch thread form. It does not mate with UNF, so the nut or tapped hole must also be UNC. For load-critical, structural or lifting joints, confirm the fastener against the engineer's specification. Fasteners are not lifting rated unless marked.

Related hex bolts: Hobson UNC Hex Bolt and Nut, Grade 5, Plain, 1/4" to 7/16" x 3/4" to 6", Hobson UNC Hex Bolt and Nut, Grade 5, Plain, 1/4" x 3", Pack of 150 and Hobson UNC Hex Bolt, Grade 8, Plain, 1/4" to 2" x 3/4" to 15", List A.