Spanner sizes

[bob121]

This was what I was thinking. So my thread gauge marked Whitworth 55° is probably an imperial set containing Whitworth guages.

[Mick D]

Hi

BSF uses the same thread form as BSW, the pitch, (TPI), is finer on BSF than its equivalent BSW - your thread gauges are correct for both.

Regards Mick

[bob121]

Went through the guages and realised that the Whitworth are marked with more detail, ie 18g5/16. I've spent most of my life using metric, it's taking time to adjust.