Hand chasing threads

I'm currently (slowly) acquiring the skill of hand chasing threads in wood, specifically boxwood which is one of the very few timbers that will take a hand chased thread. I'm using 22tpi and the threads are typically for a wooden box so the diameter can be an inch or two so not a tap and die sort of thing. Apart from striking a good thread the skill also is in matching the male and female.

It's made me wonder whether you can hand chase a thread in any metal? Is this a thing?

My understanding is that Brass Thread, which is standardised at 26 tpi, was intended for hand chasing in "olden times". This allowed production workers to readily produce items by learning only one hand feed rate for a variety of diameters.

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

It is my understanding, or possible ignorance, that thread chasers are intended for finishing screw-cut threads in the lathe when a greater accuracy of thread form is required, i.e. rounding off crests left flat after screw-cutting. I have a box full of them acquired over the years but I have never actually done any thread chasing even though I did make a hand-rest to facilitate the operation.

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

I believe hand chasing, particulerly on brass/bronze was once common. I have done it and produced useable parts. Bit like welding in that you need to be doing it regularly to "keep your hand in". I can believe it would be a very quick technique in it's day due to zero set up time.

Martin

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

Interesting video on (US) electrical fittings threads.

Electrical threads