Now, there need to be holes in these shells. I decided to make 23 smoke tubes with 6mm outer diameter and 5mm inner diameter.
I first marked the center positions with a scriber, center punched and finally drilled with the center drill:
The next step was to drill the holes up to 6mm.
And now the shell's completed. Well nearly.
I wanted to know ithe boilers capacity and so i estimated it:
The boiler will have in about 200 cm^2 heating surface. This type of boiler has an approximate capacity of 5cm^3. This means it can vaporize 5 cm^3 water per 100cm^2 surface per minute. That makes 4370 cm^3 steam per minute.
I also need the tubes:
and with some of them inserted in the shells
I turned the ends of these tubes with a mandrel on my watchmakers lathe:
This will be the smoke tube unit:
Ist small! (ruler with mm-scale)