I've re-titled this thread, so that it doesn't read as though I'm building a whole fleet of engines - one at a time is enough for me!
My first attempt at scratch building was a 'Queen'-class 2-2-2. I chose it on the grounds of simplicity, since building an uncoupled 2-2-2 is little different from building a wagon. My first step was to draw the constituent parts and then cut these out as a series of paper templates, so that I could check the fit of the parts and explore different assembly techniques, before committing to cutting any metal. I described the approach in more detail in my article 'Simply Victorian', in Railway Modeller, July 2014.
The 'Queen' (or 'Sir Alexander') model did,indeed prove very straightforward to construct,being little more than a cylindrical tube for the boiler over a folded flat plate for a 'chassis'. The cab was a simple folded brass sheet sat on the chassis behind the boiler and the flush firebox and smokebox were 'wrappers' around the boiler.
It was natural then for me to start No.184 by copying the same methods. Previous posts described how I managed to produce some reasonable line drawings from available photographs. So, as before, I copied segments of these drawings to represent the outside frames and other main component of my proposed model. I then printed these drawings on a sheet of ordinary file paper.
I cut out the individual components with scissors and a scalpel, and then stuck the parts together, using PVA adhesive. I find that hair grips are an indispensable aid to assembling paper models like this.
Now that I can visualise the 3D assembly, I can start to explore ideas on how they might fit together in a metal model. It soon became apparent that a model of No.184 will raise a number of difficulties that were not present in 'Queen'. The coupled wheels are an obvious complication but there is also the fact that these wheels intrude into the cab, which means that this can no longer be seen as a completely separate component, simply 'plonked' on the chassis at the end of construction!
Instead, I shall look at a means of construction where the cab will be integral with the rear-wheel splashers. The compromises associated with the 'narrow' 00-gauge also come into play, since these mean that the intrusion of the wheels into the cab will be much greater than in the prototype. The backhead will need to be modified, to accommodate the narrow wheel spacing.
On my 'Queen' model, the outside axle boxes were all dummies and, from some angles, the large gaps between these and the 00-gauge wheels were all too obvious. The new engine will require extended axles for the coupled drivers and outside cranks so, hopefully, these will hide the discrepancy to some extent.
I've not started to plan the superstructure yet but it is clear that the boiler will be a more complex construction than 'Queen', mainly because of the raised firebox, which will have to be a separate component. Since I am also hoping to include a motor and gearbox in this engine, rather than in the tender, as before, I shall have to think about clearances for housing these components, especially as I want to keep the footplate clear of any further intrusions!
So, I have a lot more templating to do before I can be sure that I have a viable plan - that is a subject for future posts.
I recently bought a book on the OW&WR (Jenkins, OW&WR Through Time, Amberley 2013 ) and, while the title is somewhat misleading, as it is really about the Cotswold Line to Hereford, it contains several photographs appropriate to my area, including an excellent one of a 182-class locomotive (OW&W 21-class), in original condition, at Evesham Station in 1863. This is especially useful, since it shows the back of the tender that I had not seen in other photos.
I have another book in the same series about the Fairford Branch (Jenkins, The Witney & Fairford Branch Through Time, Amberley 2013 ) and this includes useful information about the planned lines around Witney. From this book, I learned that the route via North Leigh (the subject of my own layout) arose as part of a spate of schemes during the 1840s, including the `Oxford, Witney, Cheltenham & Gloucester Independent Railway', which obtained an Act of Parliament for the construction of a `mixed gauge' line. In the parallel universe inhabited by my layout, where all this came to pass, it is now clear that the wide spacing of the tracks through North Leigh station is the result of this broad gauge heritage.