On Sun, 24 Jul 2011 00:36:18 -0700, harry wrote:

On Jul 21, 2:51Â*pm, Andy Breen wrote:


Hypothesis: in the early days of locomotive building cast iron was the
preferred material for boilers, but only a limited number of companies
could manufacture such large and complex items. As larger wrought iron
plates became available it became easier for colliery workshops and
smaller local foundaries to build boilers from wrought iron, avoiding
buying in large and expensive items from outside. The emergence of
George Stephenson as the dominant figure in railway practice from 1816
established the use of wrought iron boilers (as in the Stephenson
standard locomotive) as the norm.


You would still need some means of bending and forming flanges etc in
the plate.

For wrought iron boilers, I assume (in castings they'd be part of the main
lump out of the mould)?

You'd need flanges at the boiler ends, to attach the end plates. These
could be formed over a mandrel - within the expertise of a colliery
blacksmith? The makers of early wrought boilers don't seem to have been
bothered about having rivets through from outside to inside (nor, until
the 1840s, about having rivets from fire-side to water-side in the flue
or firebox), so the boiler plates could be either lap-jointed (overlapping
and rivetted through) or joined with a butt strap, with the rivets going
through the strap. Once again, within the abilities of a good colliery
blacksmith?
The result would be crude - but these locomotives were!

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