BA Fasteners
We're closed now for the Holiday break, we'll be back on deck from January 12th, 2026
Any orders received between now and then will go into the priority queue for immediate processing upon our return
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British Association or BA screw threads were designed for use in modelling and instrumentation
Often used in British motorcycles where threads less than 1/4 inch diameter are required, such as electricals, badge screws, carburettors etc.
Counterintuitively, as the BA number increases, the diameter decreases, and thread pitch gets finer... as below
| (BA No.) | Diameter | Threads per inch (TPI) |
| 0BA | 0.2362 inch (6.00mm) | 25.40 tpi |
| 1BA | 0.2087 inch (5.30mm) | 28.22 tpi |
| 2BA | 0.1850 inch (4.70mm) | 31.36 tpi |
| 3BA | 0.1614 inch (4.10mm) | 34.79 tpi |
| 4BA | 0.1417 inch (3.60mm) | 38.48 tpi |
| 5BA | 0.1260 inch (3.20mm) | 43.05 tpi |
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