Here goes my 2 cent's worth about copper treaded bushings. Better if you
use a no zinc bronze. Copper is too soft and its threads will tend to
distort and even pull out when a male thread is screwed in it. Like you
will always be able to tighten it more. Bronzes silver solders well.
Copper, though soft, doesn't machine well. It's "sticky" and sort of welds
to the cutting tool and this causes rough finished surfaces.
Arthur--Mexico City
Subject: Re: Boiler bushing bronze