It was normal to hand chase threads before thread systems started to be standardised in the mid 19th century. Once that happened it became practical to add a screwcutting capability to lathes. Also taps and dies started to become available in greater quanties, and better quality.

Andrew

I too have a drawer full of hand chasers from about 8 tpi to 42 tpi. (mainly external but some internal). I have a more modern set from Tracy and have used the 26 and 32 extensively, mounted on the topside for screw cutting brass fittings. However I do find it difficult to prevent "dig ins" when holding them by hand for cleaning up a screw cut thread. Incidentally, the Tracy sets are single cutters from Coventry die heads, so pick a few ups next time you see them going cheap at boot sales.

Bob

My father told me that the brass turner only had one pair of chasers, so male anď female threads were all 26 tpi, and made to fit each other, which is why the shade rings on old lampholders aren't interchangeable. The brass thread diameters were later standardised for mass production, but (contrary to popular belief) have never been a "British Standard". Dad did his apprenticeship in the later 1920s. New Practical Metalworker was published after 1936, and the second paragraph of page 929 confirms that freehand thread turning was still practised.

George