< Inner Boiler >
Inner tubeplate and backplate bored in the
lathe.
Tubes and flues. Note the front end of them
is a little tapered to ease assembly into
the smokebox tubeplate.
For firehole ring, copper sheet is rolled
and silver soldered with a short strap. The
left is a failed one and the right is a recover.
A wood mandrel supports the firehole ring
during the operation in the lathe.
Inner backplate with the firehole ring.
The sheet for inner wrapper is cut by a hacksaw
and straightened with a file over a steel
bar as a guide.
A cylindrical pan had ideal radius for the
inner wrapper's round top.
Again many of guides are used to bend the
inner wrapper.
Inner wrapper with the firebox tubeplate.
The steel screws will be replaced with the
copper rivets just before soldering.
To fit crownstay to the firebox round top,
the foot of them were pressed onto a large
steel pipe.
Small areas between the tube holes should
be prortected from overheat during soldering
operation.
Tubes and flues are silver soldered to the
inner firebox . 1mm solder wire is coiled
twice around each tubes and flues. Note the
smokebox tubeplate is used as a jig to stand
the tubes parallel.
Finished inner boiler
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