27-02-2022, 09:15 PM
Hi
The information I have suggests that unlike Unified fasteners, the dimension across the flats for the BSF and Whitworth ranges of nuts don't correspond to an exact fraction of an inch
For the nut in question, the head size is likely to be 0.820 inches or 20.83 mm. For standard fasteners this would be the head size associated with 1/2 inch BSF or pre-war 7/16 inch Whitworth. So it looks as though Austin specified a smaller than usual head as well as a different TPI.
The information I have suggests that unlike Unified fasteners, the dimension across the flats for the BSF and Whitworth ranges of nuts don't correspond to an exact fraction of an inch
For the nut in question, the head size is likely to be 0.820 inches or 20.83 mm. For standard fasteners this would be the head size associated with 1/2 inch BSF or pre-war 7/16 inch Whitworth. So it looks as though Austin specified a smaller than usual head as well as a different TPI.