I have soldered a "real" flue-boiler with water-surrounded firebox. Unfortunately, I was in such a hurry that I made it of a too thin copper sheets. As my friends predicted it deformed during a water pressure test...
Still, I believe I can use it up to 4bar, because the volume is very small and it shouldn't be dangerous.
I have decided to place throttle valve inside. It works well, though the adjusting rod bushing is a bit leaky.
I still have no burner. I want my loco to be alcohol fired and I want to use whole coal box as a tank - it is neither near nor below the firebox. I have tried to build some fancy burner, but it failed because the fuel drought was too small.
I will probably try to use 2-4 copper tubes packed with wash-up clothes.
This is the construction of my throttle-valve. The bearing ball (Φ4) is pressed against a spherical socket by turning an adjusting rod. There is also a spring that pulls the ball out (not shown).
Inspired by the Henk Bunte building Live Steam locomotives I have decided made a model of a boiler to be laser cut from sheet metal.
