....boilers! The etchings Mick D did for me already had some of the boiler/firebox/smokebox formers included, but I needed extra ones and cut them from 0.4 mm nickel silver.
Firstly I made the smokeboxes. The etches did have parts for the wrappers too, so this job was pretty easy. Form the wrappers into shape round suitably sized bar/drill shanks and solder up. The main curve I did by hand using a 20mm bar. Then I introduced a former and marked the positions of the reverse curves. The reverse curves were (slightly over-) done with a 7 mm drill shank. The wrapper was centred over the formers, and the formers brought to the front edges of the wrapper using a steel rule layed across the edges, you'll need to use your 3rd and 4th hands! Tack the main curve of the wrapper to the formers and then carefully unfold the return curves to match the lower parts of the formers.
The boilers are a lot easier. A rectangle of 0.3 mm nickel silver was cut. {lenght required x [(diameter of former-thickess of material) x pi]}. This was shaped on my slip rollers. Put the ends of the sheet backwards through the rollers first to form the required curve. This prevents the rollers producing a flat end section to your tube. See here:
The boiler bands were added from 0.2 mm strip (I know, I just like adding boiler bands) and cast tightening cleats soldered on. The boiler furnature castings were (extensively!) fettled and test fitted. (Do we all know the trick of laying abrasive paper round the boiler and 'lapping-in' the curved fixing flange of a chimney or dome?)
Note to pattern makers and casters, please please please stop making chimneys that are solid down the middle. It takes ages to bore them out, it has to be done by hand because you can't hold them in anything. Brass cast ones are just impossible to bore out and I just weigh them in.
As a finishing touch I scored the boiler clothing plate join along the top of the assembly and added some fake set screws.
Next I finish the build with the last boiler details and some tablet catchers.......