The technique is called metal spinning.
When I worked in the production machine shop of a large aerospace firm, (early '70s to early '80s)
we had been through a number of layoffs. (I survived 31 in 36+ years)
As the business tapered off, I was moved all around the shop and did lots of varied jobs as was needed.
It afforded me the opportunity to work on lots of things, machines, and techniques that were normally WAY outside my job title, training, & pay grade.
During this time, a request came from some branch of the US military for a lot of replacement parts for some sort radio antenna that had been out of production since the late '50s.
This job consisted of two spun steel parts, one about 14" in diameter and about 17" deep, and the other about 24" in diameter and about 27" deep. (both were sort of a bell-shaped cone)
As luck would have it, in the company archives back in New York, they found the original mandrels & tooling for the job.
Problem was that everyone who had ever actually done the job was long dead.
So, they handed me a book written in 1941 that had a chapter on spinning, had me set the job up, and give it a shot.
The first two parts were disasters, but then I got the hang of it, and ended up making 4 sets that passed inspection.
I found out later that they absolutely needed 3 sets, so I had made them an extra set.
The parts were shipped off to our radio division, and I never heard anymore about it.
I know I was the last one in our company to do any spinning.
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