BSW, Whitworth 5/16", Socket Screw, Cap Head, High Tensile/ 12.9, DIN 912.

BSW-Whitworth, 5/16", Cap Head, Bolt/ Socket Screw/ Allen Bolt, High Tensile (12.9), BS 2470.

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A screw is fully threaded, a bolt is partially threaded. Hence, the different name in the title, ‘Socket Screw/ Allen Bolt’. So, generally speaking the fastener is a screw in lengths around 1-2inches/ 25-50mm (depending on diameter: they can vary up to ½ Inch/ 12mm with different diameters). The fastener becomes a bolt when there is space of unthreaded area on the shank, under the head. ‘Socket,’ refers to the hexagon shaped indentation found on the top of the fasteners’ head. Here, you can use a hexagon key (Allen Key) to tighten and loosen the fastener. The length of a fastener is measured from the point at which it fully touches the material to be fastened.

They are available in the following head types:

• Cap Head
• Countersink Head
• Button Head
• Flange Button Head
• Grub 
• Shoulder - Cap Head

They are available in the following materials (please note; not every head type is available in every material):

UNITS OF MEASUREMENT FOR THREAD TYPES

British Standard Whitworth (BSW)

A thread form developed by Sir Joseph Whitworth in 1841. The thread form has rounded roots and crests, a thread angle of 55 degrees, the thread form is specified in BS 84: 1956

Image is for illustrative purposes only.

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