Saturday 6 March 2021

Roofs Part 1

I did promise a post on roofs. I'm out of sync but here it is. The roofs for the Welshpool coaches are interesting for their end shape where they curve down to an almost horizontal line. Andy Cundick, a talented, and prolific, modeller from the Wilts 009 Group, has built several of these coaches and his approach is to use some sheet metal, around 5 thou thick, snip diagonal cut outs from the end, fold it into shape and solder it up, filling the gaps with solder. It works well for Andy but I was not happy about being able to get a decent shape to the roof end.

My technique evolved over a couple of attempts. Initially I cut a piece of 5 thou brass and had it rolled by Simon since I didn't own any rolling bars. This was then taped to a piece of clean waste pipe with wide masking tape. The radius of the roof is around 26mm and the pipe is 40mm diameter which is close enough. Once it is held down securely I marked out all the holes for fittings as well as some triangular cut outs at each end. the distance in from the end is determined by the length of the balcony on the coach.

Once it is all marked out the ends are cut out with a razor saw and holes for the fittings are drilled with the bench drill. After this a similar trick approach was taken to create the inserts to go into the ends. These are a different shape to the ones cut out but again a piece of brass was taped to the pipe and marked out with a longer centre line to better fit the curve.

The inserts had to be fettled to shape and ended up needing some brass scrap to support the joint but proved the technique. What became obvious quickly was that 5 thou is too thin. It flexes just too much to hold its shape. Also with time and activity the roof uncurled and would have benefitted from being rerolled. 

In order to do a better job I decided to redo them using 10 thou brass. I also bought my own rollers so I could roll and adjust the curvature to suit whenever I needed to. The same technique was used and roofs were rolled, taped to the pipe, marked out and cut.

With 3 roofs to do and 3 more kits in the stash I wanted the soldering of the ends to be more predictable. The answer was to make a jig. Recycling a piece of Severn Models hardboard and some coffee stirrers from Caffe Nero I glued down the stirrers to hold the shape of the roof and also provided some supports for the end pieces.

It's simple and effective because it allowed me to produce these.

In the follow up post I'll cover the fittings and painting.

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