I have added another table giving details of British Standard Pipe Threads. The model engineer probably doesn′t come across these in the workshop very often. They are though, still the commonly used threads on domestic plumbing fittings. There are no tapping drill sizes as in normal use an external thread is cut on a length of pipe to screw into a ready made fitting. BSP Thread Data I have also updated the table for BA and ME threads with a little more data.