Hobson BSW Hex Set Screw, 1/2" / 1"

The Hobson BSW hex set screw has a hex head and a BSW thread, and is fitted into a tapped hole or through a clearance hole with a nut (Grade 2, mild steel, zinc plated). There are 33 items: 1/4" to 1/2", in lengths from 1/2" to 4". Grade 2 is low tensile, and corresponds to metric class 4.6.

BSW means British Thread Standard Whitworth and TPI means threads per inch.

Where this product is used

• Clamping brackets and plates to machine frames that already have threaded holes
• Fixing through a clearance hole with a nut where a fully threaded bolt suits the joint
• Adjusting and locating parts on machinery, where thread along the whole length gives more adjustment
• Dry-environment assemblies where a zinc plated finish is enough protection
• General-purpose jobs where strength is not the deciding factor
• The 33 items cover diameters from 1/4" to 1/2" and lengths from 1/2" to 4", confirm the size against your drawing before ordering

Features

• 33 items: 1/4" to 1/2"
• Grade 2, mild steel, zinc plated
• Length 1/2" to 4"
• Zinc plated finish, for indoor and sheltered locations
• Grade 2 low-carbon steel for general-purpose use

Key specifications

Choosing the right option

Choose the thread form first: the screw and the nut or tapped hole must match in thread form, diameter and pitch. Length is measured from under the head to the end of the screw. For a different strength level see Hobson BSW Hex Set Screw, Zinc Plated, 5/8" x 1-1/2" to 4".

These hex set screws are zinc plated, which means a thin electroplated layer of zinc over the steel. That is enough for dry, indoor or sheltered use; it is generally not recommended for external applications and is 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 2 is general-purpose, low-carbon imperial steel; bolts in this grade have no radial marks on the head (SAE convention). BSW is the Whitworth thread, a 55 degree imperial form found on older British-origin equipment. Match it with BSW nuts and tapped holes. For load-critical, structural or lifting joints, confirm the fastener against the engineer's specification. Fasteners are not lifting rated unless marked.

Related items: Hobson BSW Hex Set Screw, Zinc Plated, 5/8" x 1-1/2" to 4", Hobson UNC Hex Set Screw, Grade 5, Plain, 3/8" and 7/16" and Hobson UNC Hex Set Screw, Grade 5, Zinc Plated, 5/16", 3/8" and 7/16".