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
BMSW019037RS 3/16WH X 3/8 BRASS RND SLOTTED MACHINE SCREW
500 In Stock for despatch
Price Unavailable
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BMSW019050RS *3/16WH X 1/2 BRASS RND SLOTTED MACHINE SCREW
Out of Stock
£514.70 (exc VAT) per THOU
£617.64 (inc VAT)
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BMSW019062RS 3/16WH X 5/8 BRASS RND SLOTTED MACHINE SCREW
1580 In Stock for despatch
Price Unavailable
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BMSW019075RS *3/16WH X 3/4 BRASS RND SLOTTED MACHINE SCREW
200 In Stock for despatch
Price Unavailable
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BMSW019100RS *3/16WH X 1" BRASS RND SLOTTED MACHINE SCREW
80 In Stock for despatch
Price Unavailable
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BMSW019125RS *3/16WH X 1.1/4 BRASS RND SLOTTED MACHINE SCREW
300 In Stock for despatch
Price Unavailable
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BMSW019150RS *3/16WH X 1.1/2 BRASS RND SLOTTED MACHINE SCREW
150 In Stock for despatch
Price Unavailable
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BMSW019200RS *3/16WH X 2" BRASS RND SLOTTED MACHINE SCREW
50 In Stock for despatch
Price Unavailable
-
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BMSW019250RS *3/16WH X 2.1/2 BRASS RND SLOTTED MACHINE SCREW
Out of Stock
£2,710.70 (exc VAT) per THOU
£3,252.84 (inc VAT)
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BMSW019300RS *3/16WH X 3" BRASS RND SLOTTED MACHINE SCREW
1480 In Stock for despatch
Price Unavailable
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BMSW025037RS *1/4 WH X 3/8 BRASS RND SLOTTED MACHINE SCREW
150 In Stock for despatch
Price Unavailable
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BMSW025050R *1/4 WH X 1/2 BRASS RND SLOTTED MACHINE SCREW
162 In Stock for despatch
Price Unavailable
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BMSW025062RS 1/4 WH X 5/8 BRASS RND SLOTTED MACHINE SCREW
100 In Stock for despatch
Price Unavailable
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BMSW025075RS *1/4 WH X 3/4 BRASS RND SLOTTED MACHINE SCREW
15 In Stock for despatch
£613.30 (exc VAT) per THOU
£735.96 (inc VAT)
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BMSW025100RS *1/4 WH X 1" BRASS RND SLOTTED MACHINE SCREW
Out of Stock
£1,061.00 (exc VAT) per THOU
£1,273.20 (inc VAT)
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BMSW025125RS *1/4 WH X 1.1/4 BRASS RND SLOTTED MACHINE SCREW
Out of Stock
Price Unavailable
-
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BMSW025150RS *1/4 WH X 1.1/2 BRASS RND SLOTTED MACHINE SCREW
130 In Stock for despatch
Price Unavailable
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BMSW025175R *1/4 WH X 1.3/4 BRASS RND SLOTTED MACHINE SCREW
Out of Stock
£2,829.30 (exc VAT) per THOU
£3,395.16 (inc VAT)
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BMSW025200RS *1/4 WH X 2" BRASS RND SLOTTED MACHINE SCREW
Out of Stock
£1,512.50 (exc VAT) per THOU
£1,815.00 (inc VAT)
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BMSW025250RS *1/4 WH X 2.1/2 BRASS RND SLOTTED MACHINE SCREW
Out of Stock
£3,836.30 (exc VAT) per THOU
£4,603.56 (inc VAT)
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BMSW025300RS *1/4 WH X 3" BRASS RND SLOTTED MACHINE SCREW
6 In Stock for despatch
£9,833.30 (exc VAT) per THOU
£11,799.96 (inc VAT)
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BMSW031062RS 5/16WH X 5/8 BRASS RND SLOTTED MACHINE SCREW
6700 In Stock for despatch
Price Unavailable
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BMSW031075RS *5/16WH X 3/4 BRASS RND SLOTTED MACHINE SCREW
50 In Stock for despatch
Price Unavailable
-
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BMSW031100RS *5/16WH X 1" BRASS RND SLOTTED MACHINE SCREW
1750 In Stock for despatch
Price Unavailable
-
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BMSW031125RS 5/16WH X 1.1/4 BRASS RND SLOTTED MACHINE SCREW
146 In Stock for despatch
Price Unavailable
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BMSW031150RS *5/16WH X 1.1/2 BRASS RND SLOTTED MACHINE SCREW
18 In Stock for despatch
Price Unavailable
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BMSW031200RS *5/16WH X 2" BRASS RND SLOTTED MACHINE SCREW
920 In Stock for despatch
Price Unavailable
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BMSW031250RS *5/16WH X 2.1/2 BRASS RND SLOTTED MACHINE SCREW
Out of Stock
£10,415.00 (exc VAT) per THOU
£12,498.00 (inc VAT)
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BMSW031300RS *5/16WH X 3" BRASS RND SLOTTED MACHINE SCREW
Out of Stock
£9,891.50 (exc VAT) per THOU
£11,869.80 (inc VAT)
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BMSW037050RS *3/8 WH X 1/2 BRASS RND SLOTTED MACHINE SCREW
350 In Stock for despatch
Price Unavailable
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BMSW037075R *3/8 WH X 3/4 BRASS RND SLOTTED MACHINE SCREW
100 In Stock for despatch
Price Unavailable
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BMSW037100RS *3/8 WH X 1" BRASS RND SLOTTED MACHINE SCREW
Out of Stock
Price Unavailable
-
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BMSW037125RS 3/8 WH X 1.1/4 BRASS RND SLOTTED MACHINE SCREW
90 In Stock for despatch
£5,350.50 (exc VAT) per THOU
£6,420.60 (inc VAT)
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BMSW037150RS *3/8 WH X 1.1/2 BRASS RND SLOTTED MACHINE SCREW
150 In Stock for despatch
Price Unavailable
-
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BMSW037200RS *3/8 WH X 2" BRASS RND SLOTTED MACHINE SCREW
50 In Stock for despatch
Price Unavailable
-
+
BMSW037250RS *3/8 WH X 2.1/2 BRASS RND SLOTTED MACHINE SCREW
392 In Stock for despatch
Price Unavailable
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BMSW037300RS *3/8 WH X 3" BRASS RND SLOTTED MACHINE SCREW
Out of Stock
£13,743.50 (exc VAT) per THOU
£16,492.20 (inc VAT)
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BMSW050075RS 1/2 WH X 3/4 BRASS RND SLOTTED MACHINE SCREW
750 In Stock for despatch
Price Unavailable
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BMSW050150RS *1/2 WH X 1.1/2 BRASS RND SLOTTED MACHINE SCREW
Out of Stock
£13,033.00 (exc VAT) per THOU
£15,639.60 (inc VAT)
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BMSW050200RS *1/2 WH X 2" BRASS RND SLOTTED MACHINE SCREW
Out of Stock
£15,564.50 (exc VAT) per THOU
£18,677.40 (inc VAT)
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BMSW050300RS *1/2 WH X 3" BRASS RND SLOTTED MACHINE SCREW
Out of Stock
£21,266.20 (exc VAT) per THOU
£25,519.44 (inc VAT)
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