Next step was the cab roof. This is made from a piece of 10 thou nickel silver, from the waste area around a sheet of etches. This was formed to the curve by bending around a brass rod, tweaking it until it matched up to the cab front and rear profiles. It is not fully curved and should be horizontal for a bit at the sides. I achieved these flat sections by clamping it in the vice and bending with a steel rule.
For the raised beading around the edges, I soldered on lengths of 0.3mm nickel silver wire. You see the roof from the top in the photo below:
Although it would be possible to attach the roof permanently to the cab, I'm trying to avoid this to make painting easier. With my banking tank, I wasn't very happy with the fit of the roof, so this time I looked for something better. The solution is simple, and came from Simon Bolton's book Scratch-Building Model Railway Tank Locomotives. Two lengths of (0.3mm) wire are bent into the shape of a staple, and soldered to the underside of the roof. The projecting lengths of wire are bent outward a bit so that they hold the roof firmly in place, against the inside corners of the cab. It was actually quite tricky to line them up for soldering, but I managed by sticking the roof on to the cab with masking tape and tack soldering from underneath inside the cab. Then it was removed and the joints fully seamed with solder.
The next two photos show the resulting roof in place on the loco. I don't have any prototype drawings or photos of the roof, so I don't know if there should be another strip across the middle or not. For the moment, I've left it off.