"Bob Engelhardt" wrote in message ...

On 5/14/2020 9:44 PM, Christopher Tidy wrote:
I guess maybe the core was built on a steel hoop made from bent round bar,
or something like that? Not sure how you hold the back end positioned to
1/8" accuracy, though.


Then how would you get the rod out of the casting?

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Here's another ancient way to make a hollow casting:
https://thelibraryofmanufacturing.co...h_casting.html

My mother's antique pewter teapots showed the resulting rough finish inside
the S-curved spouts.