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Philip1812

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  1. Philip1812
    I’m distinctly pleased with progress over the last ten days. Having added the remaining X bracing to the legs, it occurred to me that I could easily modify them to make them even more like the supports which will eventually form the viaduct. I decided to add a middle vertical leg to each of the folding leg sections. This does add a bit of support and does make the whole structure slightly stiffer, but the main reason is purely aesthetic and I think it’s worth the extra weight.
     
    I’ve also cut out the front surface of the diorama – the proscenium arch which will frame the scene. For this I’ve used a semi-elliptical arch shape with the same proportions as Brunel’s Maidenhead bridge – this was the widest and flattest brick arch in the world at the time it was built, and I think it still is.
     
    The two new photos show the whole baseboard erected, with a spare length of strip wood taped on to show the rail level, and the baseboard with legs folded away and the proscenium arch placed in front to give an impression of the view I’m trying to create. (Note the GWR green garage door in the background!)
  2. Philip1812

    First steps

    By Philip1812,

    Background
    About three years ago I decided to take up railway modelling again after a break of about 35 years – the usual reasons: children and career followed by early retirement! The standards of all aspects of the hobby have improved so much during my time away that I was very apprehensive about my ability still to produce models of exhibition quality. Before trying to build my own layout, I decided to build a diorama to test my model making skills, before committing myself to a larger, more expensive project.
    I decided to attempt to build a model of one of Brunel’s timber viaducts and started my research. The standard work on the subject is John Binding’s aptly named “Brunel’s Cornish Viaducts” and this allowed me to make a choice of which viaduct to model. My choice was based on the length and height of the various alternatives, but having decided upon Treviddo viaduct I soon discovered that it had been well photographed and, in particular, one photo had been used on a commemorative postage stamp to mark Brunel’s bicentenary in 2006, (or to be accurate on a Post Office mini-sheet.) My project therefore morphed into a diorama which would attempt to recreate the picture on this stamp.
    A visit to Steam at Swindon produced the original of the photo used on the stamp and for about 18 months on and off I enjoyed myself greatly doing my research, in Cornwall, Kew, Swindon and York. It was a real thrill to be handling documents which had been used by Brunel and his staff 170 years before. I had to suspend starting work on the diorama for a bit to leave time for other projects and family activities, but was recently motivated to re-start by receiving an email out of the blue from a modeller in Australia asking me for my help in researching Brunellian viaducts!
     
    Drawing the Plans and First Steps
    By careful reading of Binding’s descriptions, together with information in Brian Lewis’ book “Brunel’s timber Bridges and Viaducts” and my own researches, I was able to draw up some quite reasonable plans to a scale of 1mm to the inch. This allowed me to get clear in my own mind the geometry of the various timber joints in the structure.
    I have always regarded the diorama as an experimental project which would allow me to try out different ideas and methods to see which worked best. So the first job was a suitable baseboard, and this one presented particular challenges.
    The viaduct was 486ft long – 1944mm in OO – and I wasn’t prepared to have a baseboard join half way along! This meant a rather long baseboard which would have to be very stiff and also resistant to torsional forces. I could quite imagine the effect on the matchstick-like bridge superstructure of twisting the baseboard! I eventually decided to make the baseboard 2140mm long – 7ft and ¼ inch – it seemed appropriate.
    Some measurements from the original drawings in Truro records office and the ordnance survey maps allowed me to draw out some longitudinal and transverse sections of the valley in which the viaduct was built. I’ve now cut them out in 9mm ply and checked that they fit together. They need a little bit of fettling, but eventually these will be the formers on which the ground surface is modelled.
    What I need to do now is find out how much of the formers I can safely cut away to save weight.
  3. Philip1812
    First steps in construction
     
    I’ve cut out the base, end wall and one internal strengthener with no real problems, but I ran into trouble with the front left elevation which was the first to include window apertures.
    I had bought a set of compass cutters a few weeks ago because I knew that with so many arched windows to cut out something was needed. I had anticipated that they wouldn’t be very much use for the small apertures – 3 or 4 mm radius semicircles – but should be OK for the rest. It turns out that the blade of the cutter flexes too much, with the result that they try to cut in a spiral shape rather than a circle. As a result, the eight arched windows on the front left section are a complete mess and will have to be redone. Fortunately the 40thou plasticard that I’m using will be clad with brick-embossed plasticard, so the join between the main part and the inset with the eight new windows will be hidden.
     
    The process of marking and scribing the design onto the plasticard has been quite time-consuming, but useful. I’ve discovered two significant errors, both concerned with the lack of symmetry on the rear elevation, which I’ve put right and will save a lot of waste when I come to build the large dolls house version.
     
    One and a half major structural pieces cut out, two and a half to go.
  4. Philip1812
    Building the King’s Arms
     
    Background
    About two years ago I decided to take up railway modelling again after a break of about 35 years – the usual reasons: children and career followed by early retirement! The standards of all aspects of the hobby have improved so much during my time away that I was very apprehensive about my ability still to produce models of exhibition quality. Before trying to build my own layout, I decided to build a diorama to test my model making skills, before committing myself to a larger, more expensive project.
    For about a year I enjoyed myself greatly doing research, some of it quite esoteric, in Cornwall, Kew and Swindon, about the subject of my diorama – a Brunelian timber viaduct. However, about a year ago I was given the chance to be involved in the start of a rather interesting arts project and my diorama was put on hold for a bit, though it didn’t go away. As a result of the arts project I was asked three months ago to build a doll’s house-sized model of the building in which we perform, and when I started to draw working diagrams for the doll’s house I realised that it would make an interesting model building for an urban scene on a layout.
     
    Why do I think that it’s a suitable subject for a model? It’s a Victorian pub with very intricate brickwork ornamentation and stone carving; it’s got a host of garrets and gables peeking out around the roof; it’s got a very unusual footprint – best described as a trapezium with two curved corners; and it has an upstairs performance space which is an oval with a domed roof. All in all I thought it would stretch my abilities.
     
    The prototype
    The King’s Arms in Salford was described by a journalist on The Guardian as “Britain’s most bohemian back street boozer”. It’s less than 100 metres from Salford Central station and therefore very close also to Manchester Victoria. It was built in about 1870 in a working class area and is typical of the sort of large pub that was common at that time. Its accommodation is spread over five floors and although it has been modified many times over the years, its basic shape remains the same, - especially those curved corners and the oval dome. It serves very good beer.
     
    In OO it scales out at approximately 270mm x150mm x 330mm high and would make a decent building for any layout with an industrial town centre feel where the predominant building material is brick rather than stone.
     
    Drawing the plans
    I started by brick counting from a couple of good photographs that Mr Google found for me and some others that I took myself. The first thing I noticed was that the style of the brickwork was, shall we say, lacking in uniformity! The bonding of the bricks was not one I recognised and was not consistent over the whole building. I see from this month’s edition of British Railway Modelling that Il Dottore had a similar problem recently. Thanks to his article I now know that the majority of the brickwork is laid with English Garden Bond, but his solution was exactly the same as mine – go for the nearest commercial match and not worry about complete fidelity to prototype. Having said that, the chimney stacks and the most recent alterations are plain stretcher bond which is commercially available, and the rear curve is entirely laid with header bricks, no stretchers at all, giving it an unusual and distinctive appearance, so I may try and replicate that section more accurately.
     
    The second problem I encountered was that although I was able to draw quite reasonable front, rear and side elevations from my photographs, I wasn’t able to reconcile the numbers of bricks in the curved sections with a plan that linked the front and rear of the building!
     
    Eventually I decided that I would be forced to visit the pub and take some proper measurements. Obviously I had to do a quality control check on the guest bitter whilst I was there.
    The measurements caused me to make some minor changes to my elevations, but I still could not complete the plan of the curved end with its angled wall to my complete satisfaction – I was about one and a half bricks out. Eventually, however, I spotted that because of recessed brickwork, the radius of one curved wall at measurement height was different from the radius at ground level, so, allowing for this and with a bit of creative draughtsmanship, I have finally been able to draw a plan view which I find acceptable.
     
    Now, at last, I’m finally in a position where I can take scalpel to plasticard and start construction.
  5. Philip1812
    Well, I've finally finished the main layer of the external walls. I decided to scrap completely my first attempt at the front left elevation and do it all again, without those compass cutters, rather than try to add in a replacement section. I'm moderately pleased with the walls so far, though there's one repair still to be made to one window in the rear elevation. Apart from the eight that I mucked up at my first attempt, virtually all the rest of the windows in the building are of different sizes, nevertheless it would have been more sensible to have made a template and then used that for all of the first eight, - so that's something I've learnt!
     
    The attached pic shows the pieces so far, and in particular the unusual footprint of the building and the confusing assymetry of the gable end of the building.
     
    My next task will be to attempt to bend the front right and rear elevations to the correct radius curves and angles. I'lll probably get some very strange looks in Asda using my callipers to find a bottle of the right radius to act as a former! After that I'll tackle the preparation of the various embossed layers.
  6. Philip1812
    I made some enquiries through the forum here about how much wood it was safe to cut from a beam without greatly affecting its stiffness and was advised to look at the way in which aero-modellers save weight on wing formers. But even in aero-modelling sources, there wasn’t anything much about the maths of the calculation – or at least, nothing that I could follow! It seems that the aero-modellers use a fair bit of “rule of thumb”, but they cut away really quite scary amounts of timber. I eventually compromised and have cut away a large amount of the ply, leaving ribs of at least 30mm depth and with rounded corners of about 12mm radius. The picture shows the lightened formers slotted together. This has saved over 2.5kg already. I’m pleased about the saving in mass, though a bit of me resents throwing away 1/3 of my ply!
     
    My next task, when I get a few hours spare, is to glue the formers together permanently, mark out and cut similar holes in the baseboard and then glue the formers to the baseboard.
     
    I wrote the above almost three months ago but haven't got around to posting until today!
  7. Philip1812
    I’ve joined the longitudinal and transverse formers together, using 20mm L section plastic strip from B&Q to strengthen each join. I then marked the positions of the weight saving holes in the base and cut them out. I decided not to cut holes near the positions of the leg abutments to give extra strength in this area – this turned out to be a mistake. The next step was to join the assembled formers to the base. For this I used PVA glue and panel pins and it was quite tricky to do single-handedly.
    When I checked the full assembly I fond that one of the longitudinal formers had slipped by about 3mm relative to the other and two of the transverse formers overhung the base on one side by about 2mm. All of these errors can be easily corrected later by a bit of trimming at one end and padding at the other. In the circumstances I’m quite happy to accept a maximum error of less than 0.3%.
     
    The next task was to build the abutments for attaching the foldaway legs. This was straightforward – essentially they are rectangular boxes on the underside of each end of the base.
     
    The legs themselves required a lot of careful planning and calculation before starting to cut the timber. I wanted them to be fold-awayable into the diorama but be very rigid when extended. I thought it would be a nice idea if they could reflect the general shape of the timber fans in the viaduct, so came up with a plan for two sets of legs which formed a kind of interlaced W-shape when extended. Last spring I had treated myself to a power compound mitre saw for some DIY tasks which I had to tackle at my house and this proved invaluable in cutting the ends of the legs to the correct angles. I attached the part-finished legs temporarily to the abutments with hinges, added little sockets for the other ends of the legs to fit into when erected and tried it out.
     
    Rather to my surprise, it worked.
     
    That’s when I discovered the mistake I mentioned earlier. The location sockets meant that I couldn’t access the screws to take the legs off again to finish them and the lack of weight saving holes in that area of the baseboard meant I couldn’t reach the screws on the other half of each hinge. I had to retro-cut access holes to allow me to take the legs off to finish them – still at least it meant I saved a bit more weight. The attached picture shows the baseboard at about this point.
     
    Since the picture was taken, I’ve added four more sets of X-bracing and I’m very pleased indeed with the result. The base does not wobble at all in any direction – it’s both stable and level.
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