On Jul 16, 12:51*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? 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.