WHITWORTH THREAD

WHITWORTH THREAD

Whitworth threads were the world's first national screw thread standard, devised by Sir Joseph Whitworth in 1841. They are an imperial (inch-based) system characterized by a distinct 55° thread angle and rounded roots and crests. 

Key Characteristics

  • Thread Angle: All Whitworth threads, including BSW and BSF, have a symmetrical V-profile with a 55° included angle between the thread flanks. This is a key difference from the 60° angle used in modern metric and Unified threads.
  • Thread Profile: The threads feature unique rounded roots and crests, designed to distribute stress effectively and provide excellent fatigue resistance.
  • Designation: Dimensions are specified in imperial units, using inches and "Threads Per Inch" (TPI) rather than metric pitch measurements.
  • Standardization: The standard is codified in British Standard BS 84. 

BSW vs. BSF Threads

The Whitworth system encompasses two main series for general engineering:

  • BSW (British Standard Whitworth): This is the original, coarse-pitch thread series, primarily designed for general engineering applications like holding cast iron components or locomotives together. Its coarse pitch provides superior strength in softer materials and resistance to stripping.
  • BSF (British Standard Fine): This series was developed later as a fine-pitch alternative to BSW. BSF threads have the same 55° profile as BSW but a finer pitch, which provides increased core strength and better resistance to loosening from vibration, making it common in automotive and aviation applications before metric standardisation.

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Code Description Price Quantity
SSHNW019 3/16 WH ST/ST HEX FULLNUT
Out of Stock
£23.50 (exc VAT) per HUND
£28.20 (inc VAT)
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SSHNW025 I/4 WH ST/ST HEX FULLNUT
28 In Stock for despatch
£18.30 (exc VAT) per HUND
£21.96 (inc VAT)
-
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SSHNW031 5/16 WH ST/ST HEX FULLNUT
57 In Stock for despatch
£45.00 (exc VAT) per HUND
£54.00 (inc VAT)
-
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SSHNW037 3/8 WH ST/ST HEX FULLNUT
Out of Stock
£52.70 (exc VAT) per HUND
£63.24 (inc VAT)
-
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SSHNW050 1/2 WH ST/ST HEX FULLNUT
52 In Stock for despatch
£120.77 (exc VAT) per HUND
£144.92 (inc VAT)
-
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SSHNW062 5/8 WH ST/ST HEX FULLNUT
4 In Stock for despatch
£230.00 (exc VAT) per HUND
£276.00 (inc VAT)
-
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SSHNW075 3/4 WH ST/ST HEX FULLNUT
Out of Stock
£360.00 (exc VAT) per HUND
£432.00 (inc VAT)
-
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SSHNW087 7/8 WH ST/ST HEX FULLNUT
Out of Stock
£614.40 (exc VAT) per HUND
£737.28 (inc VAT)
-
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SSHNW100 1" WH ST/ST HEX FULLNUT
21 In Stock for despatch
£768.00 (exc VAT) per HUND
£921.60 (inc VAT)
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