BSF vs BSB threads

During my apprentice days as an instrumentmaker a lot of threading was done on plain lathes with a chasing attachment,refered to as bar lathes ,due to the sliding bar carrying a single hss chaser at the cutting end of the lathe with a star nut engaging with a threaded master "hob" on the other end of the lathe mandrel, the commonest threads chased were 26 and 40 tpi and always whit form, threading on the capstan lathe was nearly always by ordinary split dies in a sliding die holder.these dies cut thousands of parts. The boss told us that in Victorian days and into the 1900s the gas fitting trade cut the millions of 26 tpi threads on brass fittings using hand chasers with amazing speed and accuracy and the operators were all on piecework,remember in those days town gas was the principle fuel for cooking and lighting,plus the thousands of street light and other commercial lighting. I still cut most threads on my Colchester and Myford with a hss chaser,both on non ferrous and steel,it produces very cheaply a full form thread,though when working up to a shoulder the opening of the half nuts and withdrawing the crosslide has to be co ordinated and quick .

I've found it, and posted the relevant pages in a new thread called Turning by Hand in the Lathe.

I did think of calling it Hand Turning in the Lathe, but that called some rather unpleasant images to mind ...

George B.