< Trial Assembly of Whole Boiler >
I tried to combine the inner and the outer assemblies but couldn't, because the tubes interfered with the throat plate. I checked whole job and found that the position of the tubes in the firebox tubeplate is 3 mm lower than the correct position! Finally the current inner assembly is useless and I have to remake it.
I made the firebox tubeplate again. Cut out the copper plate, annealed and flanged. And then open the holes for the tubes and flues.
The left is failed assembly and the right s remade tubeplate. The tubes and flues is possibly reuse by disassemble the failed assembly. Tubes, flues and front stays are made from brand-new material. The recovery took about two weeks, totally.
Finish the outer diameter of the smokebox tubeplate in the lathe. It was finished as a light hammering fit to the barrel.
The last bush to be made is the regulator outlet bush on the smokebox tubeplate. After turning in the lathe, clamp the tree-jaw on the milling stage and open screw holes.
This time the inner and the outer assemblies are successfully combined.
The foundation ring is made from copper flat bars of 6 mm thickness. First the outer edges of the ring are milled and fit to the outer firebox.
Next the inner edges are milled. Finally any gaps over 0.1 mm are eliminated by hammering and filing.
The photo shows the profiles of the foundation ring parts.
The foundation ring parts are fixed by brass screws from both the outer and the inner fireboxes. The screw hole positions are marked by a drill tip through the holes in the outer and the inner fireboxes. Finally disassemble, drill and tap screw holes.
The foundation ring is temporary fixed by screws between the inner and the outer fireboxes.
This is the inner firebox assembly with the foundation ring. Large holes in the crown stays are opened by a hole saw.
Combine the inner and the outer fireboxes again. Remove the backhead. Then the upper angles of the crown stay are clamped on the crown stay and drill holes for rivets through the roof plate.
The upper angles are temporary fixed to the roof by screws and nuts.
In case removing inner firebox, it looks like this. Each pair of the acute and obtuse angles are fixed by screws with an intermediate band plate that maintains the both angles in a desired distance.
All of the boiler components except the side stays are finished. The remaining operations are mainly silver soldering.