| THE WHITE DUCHESS A model of City of Salford with the body built almost entirely from styrene sheet Paul Heard |
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 Marking out for boiler
 Three quarter view of the finished body  Cab roof and firebox  The chassis with the ABC motor / gearbox in place  The coal pusher |
For a long time I had been tempted to build
a large locomotive, probably a Pacific of some kind. Being Great Western
by default (I grew up alongside the LSWR lines in South London, so
should really be a Southern man), there is no appropriate prototype
other than The Great Bear, so it came down to Bullied, Gresley or
Stanier. Cliff Williams' article in the February 2002 Gazette about the Martin Finney Duchess sort of solved that one for me; they really are magnificent engines. However, £500 or even £300 for a kit to start with was not really on, so I decided to see if I could build one from styrene sheet. I have modelled a lot using styrene so the prospect was not too daunting, just another challenge. Many builders start with the tender on the basis that it should be fairly straightforward and will give an idea of the general quality of the kit. In my case I started with the taper boiler and firebox, because if I couldn’t get that right I could forget the whole idea. Smokebox/boiler/firebox assembly First job is to calculate the inside diameter of the boiler at each end. The boiler consists of six thicknesses of .020in styrene. Twenty thou is roughly equal to 0.5mm so it is necessary to reduce the diameter by 6mm (six thicknesses each side of the diameter). This may seem unnecessarily thick, but there is a recess on both sides just under the nameplate which can only be cut into the finished boiler. With my Duchess I worked to 43.2 and 47.5mm OD which reduces to 37.2 and 41.5 ID. Absolute accuracy is not necessary as a slight variation will not multiply during construction. Start by building a crucifix former from .040in styrene. Note that the bottom of the boiler is considerably longer than the top at the firebox end. Cut sections to boiler length, allowing for end discs, ensuring the ends are square to the centre line and then cut the taper, half the difference either side of the centre line as the Duchess’s boiler is a true cone about the centre line. Assemble and add end discs. You should have a tapered structure with ends at right angles to the centre line; this is important when you come to add the smokebox in particular. Next it is necessary to calculate the circumference of the ID at both ends of the boiler (3.143 x diameter). Then do a dummy run on paper! Take a 10 x 16in sheet, paper first but then styrene, and draw two parallel lines (a, b) representing the front and back of the boiler, the maximum boiler length apart. From one end measure twice the larger circumference and draw a line square across the sheet (c). Now measure back, adding lines for the taper as indicated in the diagram. Cut off the end along line (e). Now offer the cut edge to line (d) and glue. For the trial run you can just roll the sheet up to check position; you will find the edges go all over the place which is the reason for the trial. If you want to avoid wasting a fair amount of styrene sheet, you can work out the minimum width you need to start with. Don’t try to shape the edge of the flat sheet, it isn’t worth it and you will need an overhang at the rear when you offer up the firebox. When working with the styrene, draw lines; scribing will crease when you try to roll it. After marking and cutting the end off the sheet, roll it round a piece of 32mm plastic pipe (plumbers' merchant), wrap that in a sheet of polythene, tape along its length, and stick it in a bowl of near-boiling water for 10 minutes. Don’t use elastic bands; I did the first time and the tension distorted the plastic. When it comes out it will be a neat roll of about the correct diameter. Once again, offer up the edge to the marked line which should give you the taper, glue and roll up, gluing as you go. A16in long sheet should give just over three layers. As you come to the end trim to align with the centre line. With the Duchess, I then did exactly the same again to give me 3mm thickness, offering the second sheet up to the edge of the first one. With other models this may not be necessary. When this has all set, push the former into the cone ensuring that the final edge of the wrap is at the bottom of the boiler, glue ends thoroughly and allow to set overnight. Next day you can trim the ends of the cone back to the former – don’t go all the way at the rear end as you will need to fit the boiler to the firebox. Boiler successful, so on with the rest of the model. The smokebox was built the same way, but is simpler as it is parallel and is only three layers thick. The square ends become vital when you come to fit the smokebox to the boiler. The firebox was trial and error to get the angles and shape right. Once again it is three layers thick. It is worth spending time on this as a lot of the character of the Duchess comes from this area which is difficult to get right. Concentrate on getting one thickness correct first. Careful paring and trimming is necessary to get a flush fit to the boiler where necessary, a delicate operation. General construction and detail The rest of the body is conventional styrene construction. Curved panels, smoke deflectors and tender sides were taken from hot water and shaped carefully by hand and then allowed to 'set'. Panels are subsequently laminated which fixes the curves. The detail on the body is the result of a lot of delicate work. Rivets, for instance, are 25 or 35thou styrene rod fitted into holes drilled in the body, glued, trimmed slightly proud with a pair of small scissors and lightly rubbed with fine wet-and-dry paper which rounds off the head. This method allows rivets on the smoke deflectors to go through to the back. Washout plugs are made by putting 1mm sq strip inside 3/32in tube so that it protrudes about .75mm and fitting that into holes drilled in the firebox sides. The chimney, dome and top feed are all made from laminated sheet carved and sanded to shape. Sandbox fillers are made from sheet and tube. Oil pipes from the lubricators are wire; a small length of sleeving left on produces the coupling gland. Lamp brackets are folded-up nickel silver strip. Two parts I am particularly proud of are the coal pusher and the backhead; both are totally fabricated from sheet, strip, tube and other bits. The backhead resulted from comparing a whitemetal casting with a photograph of the real thing; I couldn't accept the 'flat' detail on the casting. The only bought items on the body are the tender axleguards (I didn't fancy trying to make six exactly the same for such a prominent position), some etched handwheels on the backhead, handrail knobs, buffers and couplings - and, of course, nameplates. get a further coat of satin varnish. Although the body is very light, the chassis weighs just over 600 grams. When the unpainted model was running at Guildex last year it had a further 350 grams in the boiler and was hauling quite heavy eight-coach trains with ease although there was quite a bit of slip when pulling away. I intend to increase the overall weight slightly which should solve that. Information Information on City of Salford has been Chassis The chassis is of conventional construction using 1/16in brass frames and spacers. Front and centre axles are compensated. In keeping with making everything myself, I devised my own hornblocks; normal top-hat bearings running in channel soldered in the frame opening, the 'brim' filed flat on two sides of the bearing to stop it from rotating. I have subsequently decided that it wasn't much cheaper than buying proper hornblocks. Most of the motion is from Premier Components, as I do not have milling facilities, but I made the slidebars and crosshead, plus the expansion link which was not in the Premier set. Power is provide by an ABC motor/gearbox which, I have to say, is superb. Pick-up is through phosphor bronze wipers bearing on the back of the drivers and is completely concealed behind the splashers. Wheels throughout are Slater's. At the time of writing the chassis has been etch primed and had two coats of matt black, and the body two coats of matt black plus two coats of matt varnish. After transfers have been applied the body will quite difficult to locate. I have one excellent black-and-white photograph that was found at a Cornwall Group show. Basic dimensions have come from an enlarged 4mm Roche drawing. Other detail has been gleaned from what I could find in books. I have failed totally to find even a photograph that I know for sure is City of Salford's tender. The model is far from perfect, but my efforts were more that rewarded when the unpainted model won the Carlson Trophy at Guildex 2003. It was a deliberate decision to enter it unpainted to show the construction as, now it is painted, it looks just like any other model. It is difficult to put a cost on the model but, allowing for the few parts I did buy, I doubt if the body cost £40. The chassis is a different matter; much the same costs as any other model of comparable size. Although there is still some work to do on the loco, I have started on a rake of Stanier coaches to go with her; eight or ten would look nice! This is one way of producing low-cost models. Have a go, a simple 0-6-0 chassis will not cost much and now you know how to make a taper boiler there are no restrictions on the boiler there are no restrictions on the body. |
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