On Sun, 17 Jul 2011 03:52:37 -0700, Andy Dingley wrote:

On Jul 16, 12:51Â*pm, Andy Breen wrote:

How hard is it to cast a cylinder anyway? They'd been doing it for
years.

Have you read Rolt's Tools For The Job?

Yes..

A good explanation of just how
difficult cylinders were to make, and why the inability to make them
held up steam engine development for so long. For some years there was
only one foundry (John Wilkinson) that could cast a cylinder that was
acceptably cylindrical, and one boring engine that could machine them.
Watt's first commercially working engine (at Kinneil) had a cylinder
cast of block tin, rather than iron, because it was so difficult to make
usable iron cylinders.

All true - but by 1802 cylinder casting (and boring, which was the harder
part - early steam engine cylinders were fined to round by hand..) was
a much more mature technology (many of the improvements in casting and
boring, of course, having been driven by the more demanding specifications
for cannon..).
It's be fair to say that by 1800 high-quality iron casting of even large
cylinders was something that could be done by - at a rough guess -
10+ firms around the UK. Fabrication of large wrought-iron plate structures
was at a much earlier stage of development, though things were to change fast
in the next 10 years or so.

--
From the Model M of Andy Breen, speaking only for himself