BA THREAD

BA THREAD

BA (British Association) threads are a British standard for small screws and fasteners, primarily used in precision instruments, model engineering, and legacy electrical equipment. Unlike metric threads, they are designated by a number (e.g., 0BA, 2BA, 4BA), where a higher number indicates a smaller diameter. 

Key Characteristics

  • Thread Angle: BA threads have a unique, symmetrical V-profile with a 47.5° flank angle. This differs from the 60° angle used by metric and Unified threads, making them non-interchangeable.
  • Thread Profile: The threads feature rounded crests and roots to reduce stress concentrations and enhance durability in delicate applications.
  • Sizing System: The system is based on a geometric progression, with the pitch of each successive size (higher number) being approximately 0.9 times the pitch of the lower number.
  • Standardization: They are specified by British Standard BS 93:2008, which defines dimensions and tolerances for sizes 0BA to 16BA. 

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Code Description Price Quantity
SMSBA0050RS *0BA X 1/2 SLOT ROUND MACHINE SCREW
Out of Stock
£706.40 (exc VAT) per THOU
£847.68 (inc VAT)
-
+
SMSBA0100RS *0BA X 1" SLOT ROUND MACHINE SCREW
Out of Stock
£504.60 (exc VAT) per THOU
£605.52 (inc VAT)
-
+
SMSBA0100RSP *0BA X 1" SLOT ROUND MACHINE SCREW ZINC
Out of Stock
£233.70 (exc VAT) per THOU
£280.44 (inc VAT)
-
+
SMSBA0150RS *0BA X 1.1/2 SLOT ROUND MACHINE SCREW
Out of Stock
£331.50 (exc VAT) per THOU
£397.80 (inc VAT)
-
+
SMSBA0200RS *0BA X 2" SLOT ROUND MACHINE SCREW
Out of Stock
£420.50 (exc VAT) per THOU
£504.60 (inc VAT)
-
+
SMSBA1150RS *1BA X 1.1/2 SLOT ROUND MACHINE SCREW
Out of Stock
£89.30 (exc VAT) per THOU
£107.16 (inc VAT)
-
+
SMSBA2037RS *2BA X 3/8 SLOT ROUND MACHINE SCREW
Out of Stock
£44.10 (exc VAT) per THOU
£52.92 (inc VAT)
-
+
SMSBA2037RSP *2BA X 3/8 SLOT ROUND MACHINE SCREW ZINC
Out of Stock
£55.20 (exc VAT) per THOU
£66.24 (inc VAT)
-
+
SMSBA2050RS *2BA X 1/2 SLOT ROUND MACHINE SCREW
Out of Stock
£51.20 (exc VAT) per THOU
£61.44 (inc VAT)
-
+
SMSBA2062RS *2BA X 5/8 SLOT ROUND MACHINE SCREW
Out of Stock
£50.00 (exc VAT) per THOU
£60.00 (inc VAT)
-
+
SMSBA2062RSP *2BA X 5/8 SLOT ROUND MACHINE SCREW ZINC
Out of Stock
£124.40 (exc VAT) per THOU
£149.28 (inc VAT)
-
+
SMSBA2075RS *2BA X 3/4 SLOT RND MACHINE SCREW
Out of Stock
£133.30 (exc VAT) per THOU
£159.96 (inc VAT)
-
+
SMSBA2075RSP *2BA X 3/4 SLOT ROUND MACHINE SCREW ZINC
Out of Stock
£173.30 (exc VAT) per THOU
£207.96 (inc VAT)
-
+
SMSBA2100RS *2BA X 1" SLOT ROUND MACHINE SCREW
Out of Stock
£73.30 (exc VAT) per THOU
£87.96 (inc VAT)
-
+
SMSBA2100RSP *2BA X 1" SLOT ROUND MACHINE SCREW ZINC
Out of Stock
£159.90 (exc VAT) per THOU
£191.88 (inc VAT)
-
+
SMSBA2125RS *2BA X 1.1/4 SLOT ROUND MACHINE SCREW
38 In Stock for despatch
£500.00 (exc VAT) per THOU
£600.00 (inc VAT)
-
+
SMSBA2150RS *2BA X 1.1/2 SLOT ROUND MACHINE SCREW
Out of Stock
£195.30 (exc VAT) per THOU
£234.36 (inc VAT)
-
+
SMSBA2200RS *2BA X 2" SLOT ROUND MACHINE SCREW
Out of Stock
£174.70 (exc VAT) per THOU
£209.64 (inc VAT)
-
+
SMSBA2250RS *2BA X 2.1/2 SLOT ROUND MACHINE SCREW
Out of Stock
Price Unavailable
-
+
SMSBA2300RS 2BA X 3" SLOT ROUND MACHINE SCREW
38 In Stock for despatch
£1,266.70 (exc VAT) per THOU
£1,520.04 (inc VAT)
-
+
SMSBA3150RS *3BA X 1.1/2 SLOT ROUND MACHINE SCREW
Out of Stock
£113.20 (exc VAT) per THOU
£135.84 (inc VAT)
-
+
SMSBA3200RS *3BA X 2" SLOT ROUND MACHINE SCREW
Out of Stock
£129.50 (exc VAT) per THOU
£155.40 (inc VAT)
-
+
SMSBA4037RS 4BA X 3/8 SLOT RND MACHINE SCREW
Out of Stock
£56.10 (exc VAT) per THOU
£67.32 (inc VAT)
-
+
SMSBA4037RSP 4BA X 3/8 SLOT RND MACHINE SCREW ZINC
1950 In Stock for despatch
£56.10 (exc VAT) per THOU
£67.32 (inc VAT)
-
+
SMSBA4050RS *4BA X 1/2 SLOT ROUND MACHINE SCREW
Out of Stock
£44.90 (exc VAT) per THOU
£53.88 (inc VAT)
-
+
SMSBA4050RSP *4BA X 1/2 SLOT ROUND MACHINE SCREW ZINC
Out of Stock
£81.30 (exc VAT) per THOU
£97.56 (inc VAT)
-
+
SMSBA4062RS *4BA X 5/8 SLOT ROUND MACHINE SCREW
Out of Stock
£35.30 (exc VAT) per THOU
£42.36 (inc VAT)
-
+
SMSBA4075RS *4BA X 3/4 SLOT ROUND MACHINE SCREW
Out of Stock
£54.70 (exc VAT) per THOU
£65.64 (inc VAT)
-
+
SMSBA4100RS *4BA X 1" SLOT ROUND MACHINE SCREW
Out of Stock
£53.90 (exc VAT) per THOU
£64.68 (inc VAT)
-
+
SMSBA4100RSP *4BA X 1" SLOT ROUND MACHINE SCREW ZINC
Out of Stock
£118.80 (exc VAT) per THOU
£142.56 (inc VAT)
-
+
SMSBA4150RS 4BA X 1.1/2 SLOT ROUND MACHINE SCREW
50 In Stock for despatch
£72.30 (exc VAT) per THOU
£86.76 (inc VAT)
-
+
SMSBA4200RS *4BA X 2" SLOT ROUND MACHINE SCREW
Out of Stock
£94.00 (exc VAT) per THOU
£112.80 (inc VAT)
-
+
SMSBA4200RSP *4BA X 2" SLOT ROUND MACHINE SCREW ZINC
Out of Stock
£500.00 (exc VAT) per THOU
£600.00 (inc VAT)
-
+
SMSBA5037RS *5BA X 3/8" SLOT ROUND MACHINE SCREW
Out of Stock
£270.00 (exc VAT) per THOU
£324.00 (inc VAT)
-
+
SMSBA5175RSP *5BA X 1.3/4 SLOT ROUND MACHINE SCREW ZINC
Out of Stock
£230.80 (exc VAT) per THOU
£276.96 (inc VAT)
-
+
SMSBA6025RSP *6BA X 1/4 SLOT ROUND MACHINE SCREW ZINC
Out of Stock
£34.40 (exc VAT) per THOU
£41.28 (inc VAT)
-
+
SMSBA6075RS *6BA X 3/4 SLOT ROUND MACHINE SCREW
Out of Stock
£57.10 (exc VAT) per THOU
£68.52 (inc VAT)
-
+
SMSBA6075RSP *6BA X 3/4 SLOT ROUND MACHINE SCREW ZINC
Out of Stock
£38.00 (exc VAT) per THOU
£45.60 (inc VAT)
-
+
SMSBA6100RS *6BA X 1" SLOT ROUND MACHINE SCREW
Out of Stock
£133.30 (exc VAT) per THOU
£159.96 (inc VAT)
-
+
SMSBA6150RS *6BA X 1.1/2 SLOT ROUND MACHINE SCREW
276 In Stock for despatch
£118.00 (exc VAT) per THOU
£141.60 (inc VAT)
-
+
SMSBA6200RS *6BA X 2" SLOT ROUND MACHINE SCREW
Out of Stock
£204.30 (exc VAT) per THOU
£245.16 (inc VAT)
-
+
SMSBA6200RSP *6BA X 2" SLOT ROUND MACHINE SCREW ZINC
Out of Stock
£255.30 (exc VAT) per THOU
£306.36 (inc VAT)
-
+
SMSBA8025RS *8BA X 1/4 SLOT ROUND MACHINE SCREW
Out of Stock
£176.40 (exc VAT) per THOU
£211.68 (inc VAT)
-
+