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MikeOxon

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  1. MikeOxon

    A Tangled Web

    By MikeOxon,


    General
    I’ve referred before to the problems that arise from using published drawings as the basis for creating 3D models of early locomotives. The usual dictum of “find a photograph of your selected prototype” simply doesn’t apply to the years before photography became established.
     
    That leads to the next problem – so much of the information we read about early locomotives comes from books that were written decades after the time to which they refer. Even Gooch’s own ‘diary’ is considered suspect, since the pages about the early years were clearly written much later. It’s by no means a new problem either – Sekon, in his book ‘The Evolution of the Steam Locomotive’, published in 1898, made the following comment: “Readers may wonder why such obviously inaccurate statements should be published. One can only conjecture. Many lists of early locomotives have during the past few years been published. These should, however, be accepted with the very greatest caution.”. Matters have got considerably worse with the passage of much more time!
     
    We are very fortunate to have the sketch books and drawings made by the young apprentice at Swindon in the 1840s, Edward Lane, who sadly died at the age of 20. In his short life, he made an invaluable record for posterity of first-hand views of early Broad Gauge locomotives and other rolling stock. Even though many of his illustration are only rough sketches, they present a ‘from life’ impression and many of them are annotated with measurements and additional sketches of small details.
     
    Much later, early in the 20th century, another set of illustrations was produced by G.F. Bird and these appeared in a special supplement to ‘The Engineer’ magazine. Later still, after WW2, the RCTS produced a booklet covering the Broad Gauge Engines of the GWR as Part Two of a series on GWR Locomotives. On page B3, the booklet comments that “Bird's line drawings, the early ones mainly derived from the sketches and drawings made by E. T. Lane at Swindon in 1848/9, still remain a classic. They are the only known illustrations of many of the early engines and some are used yet again in this volume”. We must not, however, forget the caution sounded by Sekon back in 1892 and, from my own experience, Bird appears to have misinterpreted some of the information contained in Lane’s sketches.
     
    In replying to comment in my previous post about Leo-class engines, I wrote that “Another example I have found is the case of 'Evening Star', where Lane shows appropriate-looking safety valve covers but with figures above them that seem to indicate a much larger diameter. Bird has drawn extremely fat covers, presumably based on his reading but, to me, they do not look 'right'.”
     

    Comparison of sketch by Lane and later drawing by Bird
     
    I reported that “One day, I must study this engine in more detail”, so here goes!

    Modelling ‘Evening Star’
     
    In the case of the ‘Stars’, we are especially fortunate to have a couple of very early photographs of three Broad Gauge locomotives outside Cheltenham shed, possibly as early as 1848. One of the engines is alleged to be ‘Polar Star’, although I have not found a good reference to the source of that attribution.
     

    Early Photographs taken in Cheltenham c.1848

    According to the RCTS Part Two, ‘Evening Star’ was similar to ‘Polar Star’, so the photographs shown above are a useful point of reference.
     
    I also wanted a larger version of the Bird drawing than that shown in ‘The Engineer’ supplement published 16th December 1910, which included charts showing various Broad Gauge engines. This led me to another of the pitfalls that are frequently encountered with published drawings! I turned to Arman’s ‘Broad Gauge engines of the GWR, Part1’, published 2018, where on p.82, there is a reproduction of Bird’s drawing from the Locomotive Magazine 1901. It is immediately obvious (from the elliptical wheels) that this reproduction is compressed in the vertical direction. These distortions always have to be watched out for!
     
    Returning to the Lane sketch, I decided to create a sketch in Fusion 360, using Lane’s written dimensions. The result, shown below, looks to be proportioned similarly to the Bird drawing.
     

    My Sketch based on Lane’s Dimensions
     
    Although some Lane sketches appear to be accurately proportioned, this one clearly is not. Even some of his written dimensions appear to be incorrect. For example, the overall length of the boiler between smokebox and firebox is clearly marked as 7’ 9” (31mm in 4mm scale) but there are three figures written below, apparently referring to the boiler rings, that do not add up to this total – they are “2.3”, “4.3”, “3.2”. Perhaps the central figure refers to the boiler diameter over the cladding?
     
    At this point, I must state that I have not made any pilgrimages to Kew or York, to study original drawings. I note that there is a lot of detailed information about dimensions of the various ‘Stars’ in the RCTS booklet but I do not know the original sources. Therefore, please exercise the caution advised by Sekon, when reading the following paragraphs concerning my own speculation.
     
    Now I return to the matter of the safety valve casings. The ‘Polar Star’ photos do not show any fitted on the boiler of ‘Polar Star’, so these photos are of no help. The only guide I have is that Lane’s ‘from life’ sketch shows tall, narrow casings, similar to those on the ‘North Star’ replica in Swindon Museum, rather than the odd-looking fat tubes in Bird’s drawing.
     
    I have been looking at other Lane sketches for clues and found one of ‘Hesperus’, a ‘Sun-class’ engine, with a carefully drawn casing but, unfortunately, without any dimensions being shown. To my eyes, it looks like a better-drawn version of the casings shown on the rough sketch of ‘Evening Star’. The plinth is wider than the main column and I suggest could be the source of the “1” dimension, marked on the ‘Evening Star’ sketch. Perhaps, I am just adding more ‘errors’ by my speculations but I am influenced by the ‘jizz’ of Lane’s sketch.
     
    So I have continued to create a 3D-model in Fusion 360, drawing on the information contained in the photographs and the Bird drawing, as well as the Lane sketch, to re-create the frames and the haycock top of the firebox. The RCTS Part Two states that the firebox casing on ‘Evening Star’ was 4’ 10” long, which agrees exactly with Lane’s dimension, so I am content to use this figure.
     

     

    My 3D-model of ‘Evening Star’ created in Fusion 360
     
    Now, though, I come up against a major discrepancy between the Lane drawing of ‘Evening Star’ and the supposedly similar ‘Polar Star’, alleged to be the engine in the Cheltenham photograph.  In Lane’s sketch, the joint between the rectangular firebox and the ‘haycock’ top is well below the level of the boiler top, whereas the photograph shows a much taller rectangular box with a more ‘squashed’ haycock top.
     
    In the caption to the Cheltenham photographs on p.84 of Arman’s book ‘Broad Gauge Engines of the GWR, Part One’, he asserts that “Polar Star had its frames and boiler lengthened by 2’ 0” by 1849, so we can date the photograph as prior to that work being carried out”. I am not at all sure about that. I oriented my model in Fusion 360 as closely as I could to one of the Cheltenham photographs and the comparison shows that the boiler appears significantly longer in the photo, ahead of the driving wheels, than in my model:

     
    My 3D-model of ‘Evening Star with photograph of ‘Polar Star’
     
    As a further test, following a method I have used on other photographs, I used the ‘perspective’ control in 'Photoshop' to allow comparison between the diameter of the driving wheel (known to be 7’) and the length of the boiler in the photograph of ‘Polar Star’
     

    ‘Cheltenham Photo’ with Perspective Adjustment
     
    Knowing the diameter of the driving wheel was 7 feet, this comparison indicates the boiler length was (330/230) x 7 feet, i.e. 10 feet. This supports my suggestion that, at the time of the photograph, the frames and boiler of the ‘Star’ had been lengthened by 2 feet from the original 8 foot boiler length. The design of the firebox also matches Lane’s sketch of ‘Rising Star’ which was built with the longer boiler.
     
    It now looks as though I shall have to make a model of ‘Rising Star’ to take this investigation further!
     
    Mike
     
     
     
  2. MikeOxon

    A Tender for 'Rob Roy' - 1

    By MikeOxon,


    General
    It’s been some time since I last tackled an etched brass kit, after spending most of my time recently in learning about 3D printing and, before that, Silhouette cutting. I had to refresh my memory on ‘the rules of the game’!
     
    I bought the Broad Gauge Society kit (FL07) for a 6-wheel tender some time ago and have only just got around to its assembly. I was pleased to see that the instructions start with the reminder that “… some parts are a little over scale due to limitations of the design and etching process. You will need to trim some parts to fit.” I’ve fallen foul of this in past and had to open up some holes after folding parts, which was awkward to do. Of course, the ‘experts’ know all about these things but it’s still good to be reminded.
     

    Fig 1 Broad Gauge Tender Side
     
    Unfortunately, though, the instructions seem to contain more information about what not to do than actually providing instructions on the order of the build. I feel that one of the main reasons for buying a kit is to know that someone else has done the hard work of determining exactly how to assemble the parts in a rational order and will lead you through, step by step.
     
    This kit also appears to have been photo-reduced from a 7mm scale kit, as the embossed rivet detail is too small to press through the relatively thick brass sheet. I decided to ‘cheat’ and use the floor upside-down so that the fine embossed detail shows on the upper side. It’ll be hidden under the coal anyway and is virtually invisible in 4mm scale.
     
    So, to begin at the beginning… “Fold the tank sub-assembly (47) and offer to the floor. Check that all is square. Do not solder the sides to the floor at this stage” I assumed that it was OK to solder the other tabs to the floor because this was the only way to hold the box shape but, later, I began to wonder if this is what was actually meant.
     

    Fig 2 Water Tank Construction
     
    Then, we hit one of those deceptively simple-seeming instructions: “roll up the tank filler (20)”. Well, I’ve rolled several boilers and found it easier than predicted but, in this case, the tank filler is a tiny rectangle of brass, about 15mm x 4mm and not easy to handle, even under my illuminated magnifier. After some thought, I wrapped it around a 5mm drill shank and then teased it, with difficulty into the hole in the tank top. How to fix it? Well, there are no tabs or lugs and my tank was now a closed box with no internal access.
     

    Fig 3 Tank Filler
     
    Now the instructions start to lose their way. It inspires no confidence to read “The filler lid probably should have been one piece, the hinge being under the lip rather than as depicted. Solder the overlay to the top of the tank with the filler as a location aid.”
     
    The overlay is a large, nicely detailed sheet with no lugs or other alignment aids. The hole does have to align with the filler but how should it be soldered? There are no suggestions and, at this point, the notes seem to cease being instructions at all. The next paragraph starts “The tender, like most, has a flare.” It continues “There are thus three difficulties ...” Not very encouraging! There are then suggestions to “Back the corner on the inside with some paper-thin shim and fill it with solder.” There’s no mention of any part numbers or what is meant by ‘paper-thin shim’ and then at the end of the paragraph, we read “Some careful fitting will be required as these parts are over size.”
     
    Time to stop and think!
     
    Perhaps, the overlays could have been soldered, if the main tank component had not been folded in the first place but, instead, put on a hotplate, tinned overall, and the overlays slid into place (how?), then allowed to cool. The tank filler could then have been soldered from the back and so on …
     
    My own solution, however, was to abandon soldering at this point and to use glue to attach the overlays onto the already-formed tank assembly. This allowed the edges to be aligned carefully, using fingers
     

    Fig 4 Top overlay glued in place
     
    The folded overlay to form the coal space has no indications of where to make the folds, so trial and error was needed, to achieve a close fit into the curved recess. Fortunately, the brass is thin and flexible, so fingers were sufficient to make the shaping. I assembled an ad hoc collection of clamps to hold this overlay in place while the glue hardened.
     
    Back to the instructions “Next fit the rear plate (51), ensuring it is centred before soldering but do not solder the wrap-around ends to the sides as the side plates need to be tucked under the ends. Next form the front pieces so that the handrail holes are just on the flat sides. Finally add the side pieces, two parts to each (61), (62), (64), (65). These will need trimming so that they are equal in length when fitted.”
     
    I chose to glue the rear plate in position, using the notches in the curved top to set the centre of the curves to the sides. In order to make the flare along the top, I again used drill shanks as mandrels, using different diameters to hand-work the top edge to the required shape.
     

    Fig 5 Making the Top Flare
     
    I again used clamps to hold the overlay in place until the glue hardened. The ‘front pieces’, which are described as “(52,53) Tank, front plating” on the parts list, looked as though they would be very tricky, since they curve round the forward spurs from the tank and have very little area on which to be fixed to the outside. There is also the warning that “these parts are oversize”. Since there are two further pieces to complete the overlays along the sides, I could see that matching up all these separate sections was not going to be easy.
     
    I decided to turn back to soldering for these parts and, having measured the correct overall length, I laid the parts out along the sticky strip of a ‘Post-It’ note, to hold them in position while I applied a very thin skim of solder along each joint from the back side. This gave me a single component that I could glue into position and subsequently fold to fit around the front end. Rather to my surprise, the first attempt worked quite well.
     

    Fig 6 Soldering the Side Overlays from the back
     
    This method of construction produced a robust overlay that withstood the folding that is necessary around the front end of the tank.
     
    After completing the first side, the second went together much more easily and quickly and, hence, the main upper body of the tender is now completed.
     

     
    I now feel in need of a break and a glass of wine. The next post will be about the chassis, so we shall soon find out how well that fits together – there seem to be rather a lot of very small parts
     
    Mike
     
     
     
     
     
     
  3. MikeOxon
    Having suitably ‘girded my loins’, I decided to make a start on the under-frame for my Broad Gauge tender, initially described in my previous post.
     

    Drawing of Gooch 6-wheel Tender
     
    The section of the Instructions relating to ‘Frames and Spring Hangers’ starts by stating “Decide the type of brake gear to be modelled”. Not knowing much about such things, I set off in search of more information and the instructions helpfully referred me to ‘A Study of GWR Tenders, Broadsheet 18, White, Roger & Jolly, Mike.’ The Broad Gauge Society (BGS) has produced a memory stick containing PDFs of all ‘Broadsheet’ back-issues, so I was soon able to extend my knowledge.
     
    From that source, I learned that this type of tender first appeared in the late 1840's (1847-48) with plate frame horn-guides, and outside springs below the footplate. There were two types of suspension, with associated differences in the break (brake) gear. The most obvious visible difference was that of the drop of the 'J' shaped spring hangers. The photo in the Instruction Sheet (shown in my previous post) shows long spring hangers but it appears that short 'J' hangers were the earlier pattern and were associated with one-sided brakes, a small plate front-step, or a bar type of step.
     

    Early-type tender attached to ‘Antiquary’ (Waverley class)
     
    The record states that rebuilding to two-sided break-gear was accompanied by adopting the longer. 'J' hangers with added rubber secondary suspension. (perhaps to limit the amount of coal falling off at the sides?)  The dates of re-building are not stated but photo evidence suggests it was after 1870 and, therefore, after the period I am modelling.
     
    As a result of this research, I decided to build my model in the early form, for which the instructions tell me to “remove the triangular brake hanger brackets from the frames (37), (38).” For a start, those are the wrong part numbers – should be (29),(30) – and there is another trap for the unwary. At first glance, these parts appear to be attached to the fret by a number of tabs along one long side but do not cut these. Only cut two tabs, one at each end, as all the others are actually for fixing the frames to the floor of the tender.
     
    Somehow, I knew this was not going to be plain sailing! Those little triangular brackets were not very easy to remove. I scored lines with a knife between the main frames and the triangles and then, after clamping each frame in my simple bending jig, I broke off the unwanted parts by fatiguing them along the lines, by wriggling with fine-nosed pliers. This produced a nice clean edge that needed minimal cleaning up afterwards.
     
    The parts that are actually numbered (37), (38) are described in the parts list as ‘Frame and Spring Hanger’. The kit also contains some cast parts that are not mentioned in the Instructions but these include springs and axle boxes. Sadly, the castings do not include the J hangers at the ends of the springs. On another issue, it would have been nice if they could have included a casting for that tank filler!
     

    Frame components in kit
     
    From the instructions, the J hangers have to be fabricated by soldering together four layers of tiny brass etched parts. The method is described as follows: “Make up a jig by drilling through the spring hangers into a suitable material such as hard wood or paxolin. Wire passing through these holes will need to stand vertically. Stack three solid and one half-etch overlays (18) on each and solder.” I looked at the parts (very tiny in 4mm scale) and thought about the amount of work needed to build up 12 spring hangers and decided “There has to be a better way”
     

    J hanger components on fret
     
    One thought was to search the bazaars from some cast springs that include J hangers. There are some from Dart Castings that might be suitable. Then, I did some lateral thinking. After all, 3D-printing is all about building up parts in layers, so why not print these components as overlays to mount onto the brass main frames? Purists might object to the use of mixed materials but there are times when one has to place personal sanity first.
     
    It was actually quite easy to 3D-print the overlays. I selected the relevant parts from a drawing of the tender, shown above, converted my drawing to DXF format and opened it in ‘Fusion 360’. I then used the ‘Push/pull’ tool on selected parts of the drawing to make the overlay. The base is very thin (0.5 mm) and the springs, J hangers, axle boxes, etc. were all extruded by appropriate amounts from the surface of this base.
     

    3-D Drawing in ‘Fusion 360’
     
    It was an easy drawing to create, as I only needed to draw one spring and axle box assembly and then copy it for the other axles. The opposite side of the tender frame is a mirror image, which is created by a click of the mouse!  The actual printing time for each of these thin overlays was 10 minutes, so I had a complete set of overlays within half and hour.
     

    3-D Printed Overlays
     
    I have written before about combining 3D-printing with the use of my Silhouette cutter, in order to produce coloured panelled sides for carriages. Now, I have shown how 3D-printing can be combined with traditional sheet-brass modelling, to add additional surface detail.
     
    After surmounting this major hurdle in the build, it’s back to routine fitting and soldering. The brass frames fitted neatly into their slots in the base plate and feel nice and firm. The instructions start to get a bit meditative again, with questions about which type of drag bar to use. I’ve looked at the fret and, at the moment, cannot see the difference, so I shall take a pause and open another bottle. A nice cold Sauvignon Blanc this time, I think.
     
    I think the 3D printed frames look rather nice underneath the tender body. In my excitement, I forgot to provide openings for the pin-point axles but that’s a simple job for a small drill.
     

     
    Two views with the printed overlays loosely attached so I can continue to solder other parts later.
     
    Mike
     
     
     
     
     
     
     
     
     
  4. MikeOxon

    A Tender for No.184 - part 1

    By MikeOxon,


    general
    It's been a while since my last entry in this blog - lots of summertime activities getting in the way of modelling! I've also had that common modeller's problem of having so many things to do that it's been hard to decide where to start.
     
    I'm afraid that I have, once again, ignored Blanche's petulant pleas for new dresses and got down to the more mundane task of building a tender for No.184. I produced an outline drawing for this tender by starting from a side-on photograph of what appears to be a similar tender behind 0-6-0 No.244
     

     
     
    I then used AutoSketch to trace around the drawing and produce a cutting diagram for my Silhouette 'Portrait' cutter. I have used a diamond dressing tool as a scriber in the Silhouette pen holder, to mark out the cut lines onto brass sheet.
     

     
     
    The result showed that there was some slight movement of the scriber tip during the process and I think, in future, I shall dedicate a pen holder to this purpose and fix the scriber firmly inside the holder, by means of a ring of 'Milliput' putty.
     

     
     
    After marking out, I cut out the components using jewellers snips, before finishing the edges of the frames with a variety of needle files, to produce the curves around the axle guards. For the oval cut-out in the frames, I drilled a 3mm diam. hole and then opened it out to the correct shape by using a round needle file.
     
    Before folding the tender body, I formed the flare at the top of the sides by rolling the brass around a wooden dowel. I then made a number of short cuts into the rolled top, where the sides are folded from the back panel, so that the flare can be continued around the corners.
     

     
     
    The main structure is now complete, although there is a lot of finishing work to be done - axle boxes, etc.......
     

     
     
    Things are now moving again but there are several other projects waiting in the wings. My train of 4-wheelers is in need of a break (sic) van, which I intend to base on the well-known photograph taken at New Milford in 1873 - an earlier version than the V2, for which a kit is available from the BGS, but it's more fun to scratch-build.
     
    Mike
  5. MikeOxon

    A Tender for No.184 - part 2

    By MikeOxon,


    general
    I realise that I left matters hanging with the tender for No.184, in my post of almost two years ago!
     
    The awful truth is that I rather lost interest, when I found that I had made the frames of the locomotive too wide, so that the outside cranks tended to bind. I simply couldn’t face starting again from scratch until, quite recently, I hit on the idea of simply cutting off the folded edges of the plate which supported these frames and fitting new support members, made from short lengths of Broad-gauge bridge rail. These supports were placed closer together, taking advantage of the ‘narrow gauge’ represented by 00 wheel-spacing.
     

     
    Once I had soldered the frames onto these rails, I found that there was now sufficient clearance for the wheels to rotate freely, when the outside cranks were fitted, so that, in principle, I now have a working engine – once I get around to fitting a motor and gearbox.
     
    The tender was largely complete when I wrote the earlier post. Since then, I have added springs above the footplate, wheel-bearings, and wheels. The paint is Rustoleum Dark Green, which has the bluish tinge required for a Wolverhampton locomotive, with Burnt Umber acrylic on the frames. The grease-type axle-boxes on both the locomotive and the tender are simply small rectangles cut from a length of brass strip. Further additions, still to be applied, are toolboxes and a suitably high coal load – old photos often seem to show a remarkably large mound of coal on these small tenders!
     
    Having made these changes, I decided it was time to wander down to North Leigh and see how it was looking in the evening light. The setting sun was floodlighting the hills near the lime kiln, beyond the buildings of the creamery, while the oil lamps on the platform had already been lit.
     

     
    No.184 was heading the local service from Oxford to Witney, with its train of old coaches, probably dating back to the sixties. On the adjacent track, more modern Dean coaches can be seen, including a clerestory 6-wheeler composite to diagram U29, forming an Oxford-bound train, which was in the charge of Stella class no 3505.
     
    I was not surprised to find Amy Wilcote with her easel near the station. She seemed to feel that I have been neglecting North Leigh and wondered why I was spending so much time “thinking about those old Broad Gauge things”. I assured her that I will aim to spend more time in future, attempting to finish a few of the many projects I started – not to mention Blanche’s dresses 🙂
     
    Mike
  6. MikeOxon
    In my earlier post about the 'Scale Link' kit for a horse bus, I mentioned that I had another of these kits to make a 'Victoria' carriage, which I've now constructed.
     
    The 'Victoria' was an elegant 4-wheel vehicle, with a low and wide entrance, suitable for use by ladies wearing the voluminous skirts of the period. My example is destined to be loaded onto an open carriage truck, for the use of the local Lord of the Manor, on his annual trip to London for the Season. His wife and daughters will enjoy seeing and being seen in the Park in this handsome vehicle.
     
    Like the previous kit, this one is very delicate and somewhat fiddly to build. The first task is to identify the various parts on the fret, as the main body has a very complex outline and some of the links look more like sprue than component!
     

     
    The main body is designed to be folded to shape but is completely devoid of any tabs to facilitate holding the thing together, when formed. I decided to hold the parts in position, by hand, and then run a little superglue, with the aid of a cocktail stick, along the various joint lines.
     

     
    There's a choice of two hoods on the fret, one raised and one folded. Amazingly, the raised hood has a couple of tabs to help hold the top of the hood to the sides. Unfortunately, the appearance is nothing like a real hood, seeming as though it is made of plywood rather than fabric.
     

     
    Since my carriage will be a wagon load, I thought it most unlikely that the hood would be raised in transit (like an open umbrella in a strong wind), so I was happy to discard this part and used the folded version instead. Similarly, I discarded the rather skeletal lamps, deciding that these would be removed for travel and stored safely in the groom's compartment of the accompanying horsebox. .
     
    As with the horse bus, there are some extremely delicate parts - the steps, for example, are held by a 'thread' of brass, whereas the real coach seems to incorporate these as part of the flowing mudguards.
     
    Having learned from my previous encounter, I assembled the wheels onto their axles before fitting these to the minute slots in the hyper-thin springs. I used a dot of superglue to secure the wheels and their washers to the flat strip 'axle'. Alas, I got some excess glue on the hub and, in trying to remove it, seriously bent the hyper-thin spokes on one of the wheels. The real coach had pretty delicate looking wheels but I hope they were stronger than these!
     
    I think the angular mudguards also need replacing, to create more flowing lines that would reflect the elegance of the real carriage. I suppose that, for transport, I should throw a tarpaulin over the whole carriage but, even if the model is far from perfect, I intend to leave it exposed.
     

     
    I removed the shafts from the fore-carriage, for transport, and will lay these under the coach, on the bed of the carriage truck. That is the next vehicle that I have to build but that is another story....
     
    Mike
  7. MikeOxon

    A Year in Retrospect

    By MikeOxon,


    general
    My first post in the Forums was in July 2013 while I started this blog a little later, in August. I've not been doing much modelling recently, since other activities take up most of my time during the Summer months, but I do spend time thinking "where next?" and also taking stock of the past year.
     
    A year ago, i had just started trying to re-create some late-19th century "atmosphere", while knowing rather little about how things were actually done. Thanks to the patience and help of many members of the forums, I have learned quite a lot - or, at least, enough to realise how much I do not know!
     
    When I started this blog, I had just completed a simple conversion of a Mainline 'Dean Goods' into a fair representation of a 'Stella'-class 2-4-0. I was delighted to find that it really was possible for me to have something 'different', without needing great engineering skills! This tender-driven locomotive made me think what else could be pushed around my layout by suitable tenders.
     
    The Mainline Dean Goods has a simple chassis for the engine that consists, essentially, of a square-section plastic bar, with slots to take the axles of the driving wheels.
     

     
     
    This 'inspired' me (if that's the right word) to make a similar chassis from a length of square-section styrene tube, with slots cut for the axles. It proved an extremely simple way of making a 2-2-2 chassis, where there are no coupling rods to add complications!
     

     
     
    Once I had this 'rolling plinth', I could put anything I wanted on top - and so, my 'Queen' (or 'Sir Alexander') scratch-built locomotive was born! The next hurdle to be overcome was in realising the complex liveries used in the 19th century. Here, the availability of ink-jet printable transfer film came to my rescue and I was able to make my own lettering and lining, as I have described previously in this blog.
     

     
     
    There was still the problem of rolling stock,with complex outside frames and often on 6-wheel chassis that seemed to have no chance of negotiating the small-radius curves on my layout. Help from other forum members solved the chassis problem and the splendid thread about the Silhouette cutter solved the bodywork problem. The possibilities suddenly seemed endless!.
     
    So, I quickly 'threw together' a couple of 6-wheel coaches and created a 'special train' without too much difficulty.
     

     
     
    Technology has come to my rescue in a number of ways and I have enjoyed discovering novel ways of achieving the results I wanted. Some of these methods may not stand the test of time and I'm going to have to re-visit them. In my impatience to see quick results, I neglected some important steps, such as varnishing over some of my printed sides, so that they have acquired some quite heavy unintentional weathering as a result. Also, the fit of some of the parts that I cut out for my initial experiments is not as good as it should be. I have since read several forum posts about how styrene distorts when glued and stretches when cut, so I'll have to have another go, taking such matters into account.
     
    I feel that having explored all sorts of 'odds and ends', I'd like to 'settle down' and try to build a typical short train from the late 19th-century. Photographs have undone many of my pre-conceptions. It would appear that clerestory roofs were not as ubiquitous on the GWR as I had thought, since most of the photos I have seen of secondary services have plain arc roofs. The sort of train I have in mind can be seen here:
     

     
     
    So,some plans for the future but I'll probably get distracted by all sorts of other things , such as the Tilt Wagons, currently being discussed in a thread at http://www.rmweb.co.uk/community/index.php?/topic/86563-gwr-standard-gauge-tilt-wagons/
     
    Mike
  8. MikeOxon

    A Year in Retrospect

    By MikeOxon,


    General
    Last year, as 2020 drew towards its close and we prepared for the holiday season, I showed a collection of my North Leigh engines ‘on shed’. I think that, at that time, we were all hoping that the difficulties caused by Covid would soon be over. Sadly, as another year draws to its close, we are still in a period of uncertainty, waiting to learn what sort of threat the latest variant may pose.
     
    Whatever else has happened, I have found plenty of time to practise my modelling abilities with my 3D-printer and its associated software. I have reached a point from where I can look back on my earlier efforts and think that I learned quite a lot over the course of the year! Tasks that I found rather difficult are now just routine matters although, as with all complex software, I’m sure that I still have a great deal to learn. After all, I’ve been using Photoshop for processing photo images for very many years and am still learning new tricks!!
     
    In particular, I have developed my method of designing parts by extruding from drawings and then making a test assembly in the software, to ensure that everything will fit together correctly.


    Overview of my 3D-modelling Method
     
    I feel that I’ve had a creative year, which started by my producing models of a train from the early days of the GWR, based on a lithograph by J.C.Bourne. These models included a Fire-Fly class engine, together with a train including a Passenger Luggage Box, Open 2nd-class Carriage, Posting Carriage, Horse Box, and Carriage Truck.


    My Model of Fire-Fly class ‘Argus’
     
    As any regular readers of my blog will know, I started my Broad Gauge modelling by creating models of the engines and stock that were recorded in the official report on the accident which took place near Bullo Pill in 1868.
     
    I then branched out into building various other models, until the wheel unexpectedly turned full-circle. I set out to model one of the Gooch ‘bogie-class’ engines, which I had thought of as South Devon engines, only to find that several worked the Forest of Dean line from Bullo Pill!  I also discovered that some members of the Sir Watkin class were allocated to Bull Pill for a few years, before gauge conversion took place there in 1872.


    My model of Sir Watkin class 0-6-0T
     
    For the lining on the side tanks, I returned to a method I described in detail a few years ago.  The main difference now is that I used my Silhouette cutter to create the shapes from self-coloured adhesive vinyl, which I teased into position with cocktail sticks before pressing down firmly.
     
    Bullo Pill & The Forest of Dean Branch
     
    Bullo Pill lies on the railway from Gloucester to South Wales, at a point where the line runs between the Western bank of the River Severn and the Forest of Dean. At the beginning of the 19th century, a tramway was built to bring coal and iron ore from the mines and quarries in the Forest down to a small dock at Bullo Pill. The tramway passed through what was then the longest tramway tunnel in the world at Haie Hill. In the 1850s,  Brunel was tasked with converting the tramway into a Broad Gauge railway, which involved widening of the Haie Hill tunnel and the construction of additional tunnels further up the line. It was at that time that my wife’s Gt-Gt-Grandfather arrived in the village of Soudley, at the upper end of the Haie Hill tunnel, where the family lived near the Iron Works.
     


    Soudley Iron Works – Haie Hill Tunnel entrance is behind the dark tree on LHS
     
    Several of the sons from this family, including my wife’s Gt-Grandfather, started their GWR careers at Bullo Pill in the 1860s, as I have described in an earlier post. Bullo Pill Junction connected the Forest of Dean Railway to the GWR main line, with additional branches into the dock area. Tipping machinery was installed at the dock, to transfer coal and iron ore from railway wagons into barges bound for South Wales and across the River Severn.
     
     

    Bullo Pill Dock
     
    There was quite a complex network of railway tracks around the dock and to loading jetties on the banks of the River Severn, as shown in the section of Ordnance Survey 25” map, below:
     

    Map of Bullo Pill Dock
     
    Th site of the Mail Train accident, which started my interest in Broad Gauge modelling, was about one mile (1.6 km) South of here, on the main line than can be seen on the LHS of the map, running North-South.
     
    End of Year Overview
     
    My modelling activities this year have added several items of stock which are appropriate for operations on the Forest of Dean Branch, down to this dock.
     
    I thought that, as an ‘End of Year’ overview, I would show my Broad Gauge models in a ‘Bullo Pill’ context. Collecting them together has revealed just how much detailing remains to be completed.  Please don’t look too closely!  I even had to have an extra 3D-printing session, to produce some additional roofs, wheels, and other small parts, which had been ‘shared’ between different vehicles!
     
    After taking my photo, I spent some time with Photoshop, blending in a ‘Bullo Pill dock’ back-scene. It’s given me some ideas for creating a diorama – something to think about for next year.
     

    My BG Model Collection, set in a Bullo Pill context
     
    May I conclude by thanking my readers for all the encouragement you have given me over the year and send you my best wishes for the coming Holiday season.
     
    Mike
  9. MikeOxon

    A Year in Retrospect

    By MikeOxon,

    Whereas 2014 was a time of heady excitement for me, as I started to realise the possibilities of my new Silhouette cutter, 2015 has been more a period of consolidation.
     
    The potential to build my own timber-framed carriages meant that my aim of re-creating a small glimpse of the Victorian railway scene became a reality through 2014 and, inspired by these possibilities, I also embarked on a spree of kit building and locomotive construction.
     

    Locomotives at North Leigh Station – the square outline of the Belpaire firebox on 'Stella'
    contrasting with the flowing curves of Armstrong's 'Queen' class.
     
    By the beginning of 2015, I had produced a range of vehicles dating back to the middle of the 19th century, although most of my construction techniques were experimental and needed more development. As a result, progress during 2015 has been relatively slow but I feel that the quality of my constructions has improved considerably.
     
    Early in 2015, I completed the construction of a model of one of the first standard-gauge locomotives to run on the GWR – No.184, originally built for the Oxford, Worcester and Wolverhampton Railway, before its take-over by the GWR. A tender for this locomotive is still outstanding but I have made a little progress since my previous entry, by soldering the upper body to the chassis.
     
    As I described in my earlier entry, I left 'tabs' along the lower edges of the body sides. I folded these tabs inwards so that they would sit on the flat top of the chassis after folding the upper body into a 'U'-shape. I cleaned these tabs and the mating surfaces on the chassis, before applying some phosphoric acid flux and tinning these areas with 60/40 solder. I then placed the 'U'-shaped upper body panels on the chassis, making sure that the sides and back were all in their correct positions, and used solder to 'tack' down the open ends of the 'U' (at the front of the tender). Once everything was in alignment, I used the soldering iron to 'sweat' the pre-tinned parts together, along the whole length of the mating surfaces.
     

    Preparing the Tender components. I dilute my own flux from Hydroponics pH-control phosphoric acid.
     
    I also tinned the flare that I had formed around the top of the tender body and used the solder to smooth over the gaps between the brass fingers that I had cut to form the curve between the sides and the back of the body.
     

    A skim of solder stiffens the tender flare and fills in the curved corners.
     
    Throughout 2015, I turned my attention to the types of carriage that preceded the familiar Dean designs, which were constructed from the early 1870s, after completion of the 'new' carriage works at Swindon. From a modelling point of view, these earlier carriages are fairly simple, being of slab-sided design, with flat ends. On the other hand, prototype information is sparse, so key dimensions had to be inferred by comparing several old photographs.
     
    I eventually developed a method of construction based on a strong inner shell, onto which I applied 'decorated' sides and Silhouette-cut outside framing. I am particularly pleased with the passenger brake van that is based on vehicles that appear in an 1873 photograph of New Milford, shortly after gauge conversion.
     

    Early GWR Passenger Brake Van still lacking finishing touches, including the all-important brakes!
     
    Mention of gauge conversion acts as a reminder that the Great Western Railway was conceived as a broad gauge railway and that standard gauge stock infiltrated slowly, as a result of acquisition of what became the 'Northern Division'. I now feel that to take my historical interests further, I need to start exploring the types of rolling stick associated with the broad gauge.
     

    GWR Broad Gauge 'Single' from K's 'Milestones' kit
     
    I built a static model of a 'Rover-class' Gooch single many years ago from a K's 'Milestones' kit, so my initial thought is to start to build a diorama to house this locomotive and then to add some appropriate rolling stock. There's a lot to learn so, to help the process, I have recently joined the Broad Gauge Society. These plans are for the future and will hopefully be carried forward during 2016.
     
    In the meantime, I have been exploring a little more of the legacy of Amy Wilcote's paintings and found one depicting the lime kilns, which were built into the hillside above North Leigh station. A narrow-gauge horse-drawn 'tramway' was used to bring lime from the kiln down to an exchange platform, where it could be transferred to standard gauge wagons in the goods sidings adjacent to the station.
     

    Another 'painting' from my 'Amy Wilcote' collection
     
    Mike
  10. MikeOxon

    Adding Cladding

    By MikeOxon,


    General
    In commenting on an earlier post, Michael Edge pointed out that the visible diameter of a locomotive boiler is greater than the diameter of the metal boiler itself and he suggested that I should have bought a larger diameter tube for my model of 'Tantalus'.
     
    I had already been thinking about how to add the visible boiler rings and then had the idea “why not 3D-print the boiler cladding?” After all, the prototype boiler was metal, whereas the cladding was initially of wooden planks, then with an iron covering over the wood, and later, a range of different materials, such as asbestos, were used.  In all cases, the cladding was an insulator and, therefore, non-metallic.  So, I would only be following prototypical practice if I added a PLA cladding as the insulation on my own model boiler.
     

     
    A few years ago, I measured the cladding thickness on one of the boilers at Didcot Railway Centre, using my ever-ready measuring stick. (Sadly, they wouldn’t let me strip some cladding off ‘Iron Duke’, to measure that one). Two inches thickness translates into 0.67 mm in 4mm-scale. All I needed to do was to print a cylindrical sleeve of 0.67mm thickness and add the visible bands in the appropriate places. This last requirement gave me some food for thought but I eventually came up with a very simple method.
     
    The Gooch Boiler had three intermediate bands, dividing the length of the boiler into four equal segments, with an additional band at each end, adjacent to firebox and smokebox respectively. My easy solution was to design one section, with a band at one end and then copy the additional segments and join them all together, to create the complete cladding. That left one additional ring to be added at the final end. I illustrate the steps, when using ‘Fusion 360’ below:
     

     
    After extruding the first segment, with its ring, I copied it to make 2 rings and copied again to make 4. For the final ring, I split the ‘body’ 0.5mm from the end and extruded the top part to make the final ring. When printed, the cladding sleeve looks as shown below (taken on the printer bed):
     

     
    The printed tube slid smoothly but firmly over the brass-tube boiler:
     

     
    The difference in diameter is not that obvious but another advantage of this method was that I could include the boiler bands in the 3D print, so solving a secondary problem in completing the model.
     
    My model of 'Tantalus' now looks as shown below, the measured outside diameter of the clad boiler being 19.3mm. There is, of course, quite a lot of work still to be done on my model, in terms of ‘fixtures and fittings’
     

     
     
     
    Mike
  11. MikeOxon
    One idea leads to another; in this case, I have tried extending the idea that I showed in an earlier post of adding cladding to a brass-tube boiler by 3D-printing an outer sleeve.
     

    3D-printed boiler cladding
     
    During my early ‘learning curve’ with 3D-printing (i.e. about a year ago), I made some broad-gauge carriages, as described in a short series of blog posts.  Printing the complete carriage as a single task had several advantages, such as including internal partitions and seats, but also created difficulties in making window openings and other features on the vertical sides. For the window openings, I had to include support structures which proved quite difficult to remove without leaving rough edges around the windows.
     

    3D-printed Broad Gauge Carriage
     
    There is the additional point that each print took about 8 hours to complete, which is a serious deterrent to much experimentation - my preferred method of working.
     
    As a result, the completed carriages lacked detail, so one solution that I explored was to use my Silhouette cutter to add outside frames to plain carriage sides, as shown in my Pre-Grouping blog
     
    My new ‘cladding’ idea, however, is to add a thin skin to the previously printed carriage body. This ‘skin’ can carry the additional detailing to represent external mouldings and other fittings. My initial experiment was to make a ‘skin’ only 0.5 mm (20 thou) thick, which could be laid flat on the printer bed. With this method, cut-outs for windows could be made with no requirement for any support structures, while slots in the surface could be made to mark the edges of doors. External mouldings could also be extruded, by simply increasing the thickness of the skin in the required locations – again with no need for any support structures. The other major advantage is that a detailed skin of this type prints in a few minutes, so it is easy to correct mistakes and make improvements, without committing to extended time-scales.
     
    As usual, there were some lessons to be learned. I made the initial drawings of the carriage side in ‘Autosketch’ and then transferred these to ‘Fusion 360’ in DXF format. I placed the drawing on the horizontal (XY) plane and then extruded the main panels to a depth of 0.5 mm, excluding the window areas and door edges and mouldings. After this first extrusion, I selected each of the door edges and extruded these by only 0.25 mm, so that they were recessed below the main surface. In a similar way, I extruded the mouldings by 0.75 mm, to raise them above the panels.
     

    3D-model for side overlay
     
    For the louvres above the doors, I raised each rectangle and then applied the ‘chamfer’ tool to achieve the required angle of each louvre individually.
     

    chamfered louvres above window
     
    My first print, which took about 9 minutes, showed that some of my details, especially the raised mouldings, were too fine to appear in the final print. In fact, I should have used the pre-view facility in the ‘Cura’ slicing software, which would have warned me that this was going to happen.
     
    It is all too easy to draw details that are too small to be realised by my printer, in which the print head has a diameter of 0.4 mm. It is interesting to note that narrow slots (0,25 mm), as at the edges of doors, do appear but similarly-sized raised features do not appear. Modifying the drawing meant that I had to get to grips with the drawing tools in ‘Fusion 360’, which are broadly similar to those in ‘Autosketch’ but with some key differences.
     
    One important aspect when creating drawings in a 3D program is that you have to decide in which plane the drawing is required to appear. This can sometimes be tricky, especially after the initial drawing has been extruded to create new surfaces above the original plane. The first action, when entering ‘drawing mode’ is to select the drawing plane. By selecting the top surface of the carriage side, I could draw new profiles for the arc-shaped mouldings at each end of the carriage. I could then extrude these new sections by 0.25 mm above the top surface, to match the original mouldings (which had been extruded by 0.75 mm from the original drawing plane). It is essential to keep a clear head when making these modifications!
     
    For the straight side-mouldings, I used a different method by selecting the vertical edges of the moulding, where they rise above the carriage side. The ‘Move’ tool can then be used to move these edges in order to increase the width of the mouldings to a printable size.
     

    Changing the width of a moulding
     
    After making these changes, I transferred the 3D model to ‘Cura’ and this time, I remembered to use the ‘Preview’ mode, to check that the details would actually print! I also set the line-width to 0.3 mm, even though my print head is 0.4 mm diameter. This can improve the smoothness of very thin panels like these. I suspect this is because the nozzle is circular, so that a rectangular grid of lines benefits from slightly closer spacing between successive passes of the print-head.
     
    All looked good in the pre-view, so I proceeded to another print, which again took only a few minutes to complete.
     
    When printing these very thin ‘skins’, the ‘Cura’ software automatically produces frames around the window openings and the edges of the sides, which, in the case of the windows, provides a fair representation of the bolections. The main panels are very thin indeed and peel off the printer bed like plastic tape but I found they were sufficiently robust to resist tearing.
     

    Peeling side-skin off printer bed
     
    I smeared some PVA adhesive on the original carriage side and carefully laid my new cladding in alignment with the existing window openings, which already had the droplights represented. Since I had previously sprayed the carriage body with red primer, the droplights automatically appeared in a suitable red colour. As early GWR carriages were painted brown overall, the final painting job was very straight-forward. Although diagonal lines from the printing process were visible on the surfaces of the printed panels, these were sufficiently fine to cease being noticeable under a coat of paint.
     

    Skin applied to Carriage Body
     
    I shall continue to experiment with different parameters for the printing process and, if making new carriages, I would make the original sides a little thinner, to allow a thicker surface skin to be applied without increasing the overall thickness by too much.  I think my present skins are on the limit of what my current printer can reasonably accomplish.
     
    Mike
     
     
     
     
  12. MikeOxon

    Aeolus Chassis and Tender

    By MikeOxon,


    General
    I constructed the chassis for my Aeolus model from several separately printed components:
     
    Outside frames, with rivet detail Inside frames, with splasher tops Front Buffer beam, linking frames Rear drag-bar and footplate, linking frames  
    After printing these parts, I fused them together by welding the seams using a fine-tip soldering iron set to 200°C. This proved easier than I expected, partly because the PLA plastic has low thermal conductivity, so it was possibly to align and hold the parts in place by hand. After softening the plastic, it does not ‘set’ instantly so it is necessary to continue holding the parts together for a few seconds after making each joint. The result of this process when applied to the inside frames is shown below:
     

    Frames fused together by means of a soldering iron tip.
     
    I created 3D-printed wheels of both 6’ and 3’ (prototype) diameters, using the method I have described in previous posts. Unusually, I couldn’t see a reference to the numbers of spokes on the sketches by E.T.Lane, so made my own judgement – rather more spokes than shown on the Bird drawing, which wasn’t created until the early 20th century.
     
    I then added the outside frames, again using a soldering iron to attach them at the ends but leaving some flexibility in the centre, so that they could be pulled out a little, to allow the ends of the driving axle to be passed through since, unusually, the axle is positioned above these frames.
     
    The engine was now rapidly reaching completion. As an experiment, I thought I might try using 3D-printing for the guard-rail ‘fences’ on each side of the footplate. I reasoned that these were not so different from the slatted windows I had already created successfully for BG cattle wagons.  In fact, they did print accurately and cleanly and, although they could easily be damaged by rough handling, they were sufficiently robust for a display model.
     

    3D-printed guard rails on printer bed
     
    I provided ‘feet’ below the end pillars that could be firmly attached to the footplate by using a touch of the soldering iron tip. The appearance of the model was now as shown below:
     

    Rear three-quarter view of my Aeolus model
     
     
    Air Resistance Experiments
     
    In my previous post, I mentioned a pillar or stanchion at the front of the engine, shown on the Lane sketches with no indication of its purpose. I speculated that there might have been a curved rail around the front of the engine.  Since writing that, I have come across the following passage in MacDermot’s ‘History of the GWR’, Vol. One. There is a lengthy chapter about the design and performance of the early broad-gauge locomotives. Concerning the engines supplied by Tayleur, of which Aeolus was one, it records that: “Another interesting suggestion is contained in one of Brunel's letters to Tayleur & Co: 'A bow or round front to take off the direct action of the air against the flat surface of the smokebox.’ Nothing appears in the correspondence or other papers to show whether this was actually fitted to any engines, though it seems likely to have been tried.”
     
    Did the stanchion on top of the mounting for the weigh-bar support a curved bar across the font of the engine to carry such a bow front? Was the unusual position of the valve gear also in some way connected with such experiments? With those thoughts in mind, the front of Aeolus could possibly have looked like this at some period:
     

    Stanchion and curved rail supporting bow-front
     
    … or even, like this (shades of LMS 'Coronation'):
     

    My model Aeolus with Bow Front
     
    Before this thread merges into ‘Imaginary Locomotives’, I’d better take my model to the paint shop. I shall add the control rods and levers, of which there are several, after painting the main structures.
     
     

    Controls and actuating rods on Aeolus (drawings by E.T. Lane) - revised
     
    Adding a Tender
     
    Unlike her sister engine ‘Vulcan’, which was converted into a tank engine, ‘Aeolus’ was re-built as a tender engine and we are very fortunate that young Lane also made sketches of this tender, as shown below:
     

    Aeolus Tender, sketched by E.T. Lane.
     
    Like many of Lane’s other sketches, these included his inimitable addition of details; in this case, these appear to be mainly of brake gear not included on the main sketch.
     
    The main sketch shows the interesting feature that the sides of the tender extend outside the wheels and there are ‘cut-outs’ to provide access to the springs, presumably for lubrication purposes. This aspect of the design led me to adopt a slightly different method of construction from previous tenders that I have built.
     
    I started by drawing the outer sides of the tender, using the sketches and dimensions provided by Lane. The sides have a ‘flare’ at the top and oval cut-outs over the springs, for which the dimensions were helpfully shown by Lane in one of his sub-sketches. I then drew the back of the tender, with curved ends and flare to meet the profile of the sides.  Next, (1) I created a simple flat floor, with cut-outs for the wheels, to hold the sides at the appropriate distance apart for a broad-gauge tender. (2) Using the surface of the floor as a template, I sketched the outlines for an inner frame that (3) I extruded upwards to support the top plate of the tender. I also drew the outlines of the springs on the outer faces of the inner frame and extruded these to form the springs, visible through the openings in the body sides. (4) Finally, I added the top plate of the tender. I illustrate these steps below:
     

    Stages in constructing my Model Tender
     
    I had broken the tender model into parts such that each had a flat side to lie on the printer bed. After printing these parts appeared as shown below:
     

    Printer Tender Components on 3D-printer bed
     
    Final assembly of the tender was simply a matter of running a soldering iron, set to 200°C, along the seams, to fuse the various parts together.
     

     
    My 3D-printed Tender model
     
    So now the tender can join its partner engine in the paint shop…..
     
    Mike
  13. MikeOxon

    Aeolus in Context

    By MikeOxon,


    General
    At the end of my previous post , I wrote that the engine and tender would next enter the paint shop. Because the various major components (boiler, firebox, etc.) were all printed separately and simply plugged together, it was easy to paint each part in its appropriate colour, with no masking required.
     
    I use acrylic paints, which I like to apply in the manner of water colour. I use an alcohol/water mix to ‘wet’ the surface and then add pigment to achieve the desired depth of colour. For the boiler and firebox, I used ‘Rustoleum Painters Touch’ Dark Green, which has a distinctly bluish hue, mixed with black to achieve my preferred broad-gauge ‘dark blue-green’ appearance. Other parts were painted black, with GWR Coach Brown for the frames. Smaller areas were Chinese Red for the buffer beam and Antique Gold for the bright-work.
     
    Once the painting of the body was completed, I added a few small parts, including the curved brackets at the outer ends of firebox and smokebox. I actually printed these brackets together with a set of wheels since, when laid flat on the printer bed, small parts like these only take a few minutes for the whole batch to complete,
     

    Small Parts on Printer Bed
     
    I have found that the gelled type of superglue is good for attaching such small items. I apply a thin film of glue to the mating surfaces, using a cocktail stick and, while gripping the small part in a pair of tweezers, press it firmly into position against the main body. I check under an illuminated magnifier, to ensure that the alignment is correct.
     

    Bracket attached to side of Smokebox
     
    By using a very thin film of glue, I ensure there is no unsightly overspill and the joint sets almost immediately. Unfortunately, I couldn’t use my favourite technique of fusing parts together with a soldering iron, because they are in visually exposed positions and the tiny areas involved are too difficult to melt cleanly, without damaging the surface finish.  With the brackets attached and the wheels fitted, my models of Aeolus and tender now look like this:
     

    Fresh from the paint-shop – Aeolus and tender
     
    As I have mentioned before, when commenting on earlier posts, one of my aims in building models is to visualise the progress of engine design throughout the early years of railway development.  I find that models do this for me far more effectively than viewing 2D illustrations. 
     
    For example, this photo of 'Vulcan' (a sister engine to ‘Aeolus’) looks fairly normal, when seen in isolation, but put a model against later designs and the differences in 'scale' become immediately obvious.  I am now able to place my model of ‘Aeolus’ head to head with my model of ‘Argus’ , a member of Gooch’s pioneering Fire Fly class:
     

    My models of Aeolus and Argus, head-to-head
     
    The undersized boiler and lightweight frame construction are clearly seen in ‘Aeolus’, which was originally built in an attempt to meet Brunel’s virtually impossible specifications. When Gooch built his Fire Fly class, he recognised the need for adequate boiler size and heating surfaces, together with robust components able to withstand the rigours of regular express operations.
     
    ‘Aeolus’ was built in 1837, while the first of the Fire Fly class appeared in 1840, showing remarkable development within just a few years. Gooch went on to produce the much larger 4-2-2 ‘singles’, staring with ‘Iron Duke’, built in 1847. I only have a model of one of the later re-builds of these engines but the dimensions were much the same as the original engines – the comparison below shows the extraordinary increase in size that these engines represented:
     

    My model of Aeolus with Rover-class 4-2-2
     
    My model shows ‘Aeolus’ following a re-build in 1843, which turned it into a small but useful engine for light duties. Apparently, she served for a short period on the Abingdon Branch, which happens to be my home town! This type of usage could be seen as a precursor to the small-engine auto-trains, introduced by the GWR early in the 20th century.
     

    Abingdon Station c.1863
     
    Mike
  14. MikeOxon

    Aeolus Valve Gear

    By MikeOxon,


    General
    Interpreting the Valve Motion
     
    At the end of my previous post, I commented on the surprising layout of the valve gear, as shown on the Lane sketches. The Works drawing of the engine, as originally designed, shows a more usual arrangement, with the weigh-bar placed under the boiler behind the smokebox.
     
    Following further research, however, I have re-interpreted the drawings of Aeolus by E.T. Lane and have, therefore, revised this post on 16th April.
     
    According to the recently published book by Brian Arman: ‘BG Engines – Part 3’, several engines built during the 1840s were fitted with a regulator that was placed immediately above the cylinders. Drawings of, for example, the ‘Prince’ class show that the regulator was operated by levers from a shaft across the front of the smokebox, by means of a control on the right-hand side of the footplate.
     
    I had not been happy with my previous thought that these components might have represented a ‘throw back’ to much earlier type of valve gear as used on Stephenson’s ‘Planet’ series of engines. It appears that Gooch started fitting his fixed link expansion gear from 1843, so I now suggest that the rebuilt Aeolus may have been one of the first engines to have been fitted with this gear. Far from being a ‘throw back’, this engine may have a been a test-bed for the new arrangement, which was fitted to Great Western and other engines shortly afterwards.
     
    This change of interpretation does not actually affect the design of my model very much, it is simply that the parts that I have modelled serve a different purpose from what I initially had thought. The new interpretation is much more convincing than my earlier thoughts.
     
    Initially, I produced every piece of the regulator mechanism as a separate ‘body’, so that I could move them all around independently to what seemed to be the most appropriate positions. The plausible outcome looked as below:
     

    Potential Layout of regulator mechanism in ‘Fusion 360’
     
    The next requirement is to provide supports for all these gubbins and, on this matter, I find the available sketches and drawings very confusing.
     
    Lane’s sketches, which were clearly used as the basis of the much later G.F.Bird drawings, show what appears to be a rather massive support structure carrying a shaped boss to hold the transverse shaft, presumably in the centre-line of the locomotive. There is no clear indication of how the outer ends of the shaft were supported. As an interim measure, I decided to add support brackets extending forward from the smokebox, as shown in drawings of  ‘Prince’, but there is no indication of such supports in the Lane sketches. There also seems to be a pillar supporting horizontal bars but with no indication of where these were placed laterally. Was there perhaps a curved rail around the front of the engine?
     

    20th Century drawing by G.F. Bird, derived from Lane’s sketches
     
     
    Another puzzle is provided by those rather splendid curved side-brackets shown on the original Works drawing of ‘Aeolus’. It is not clear whether these were retained when the smaller wheels and consequently lower outside frames, were fitted during re-building. It is also not clear where they appeared along the length of the engine, although the photograph of ‘Vulcan’ suggests they were at the front of the smokebox and rear of the firebox, with intermediate straight supports to the sides of the boiler. Bird seems to have assumed this in his drawing but it not clear on Lane’s sketches.
     
    Adding Surface Details
     
    One of the pleasures of using 3D modelling tools is the ability to add rows of rivets, either in regular arrays or following a defined path, by using a few keystrokes and the ‘pattern’ commands.
     
    For the frames, I drew one rivet and then used the rectangular pattern tool to create a 2 x 36 array for all the rivets on one side and then the Copy command to replicate them on the other side. For the smokebox front, I drew one rivet and then told them to follow a path around the edge of the smokebox – job done! With these additions, my 3D model in ‘Fusion 360’ looks like this:
     

    Assembly of parts within ‘Fusion 360’
     
    Preparation for Printing
     
    As I have pointed out before, there is a difference between a 3D model and a printable 3D model.
     
    My approach is to break the complete model down into several parts that can be printed individually and then assembled as a ‘kit’. In deciding how to separate the parts, I try to ensure that each part has a flat surface which can be laid on my FDM printer bed. An advantage of this approach is that the print times for individual parts can be quite short so, if some re-design is necessary, it can be done without having to re-print the entire model.
     
    Smokebox Front
     
    I felt that the most demanding task for my printer would be to reproduce the details on the smokebox front, including the supports for the valve gear. For this reason, I did a test print of this part first, since the overall success of my model depends on how well this region can be represented. After printing, my first trial looked as below (Note that I shall print the weigh bars and levers separately.):
     

    My first test 3D print of the Smokebox Front
     
    There were a few stray strands of filament that had to be carefully removed with fine tweezers but overall, I was very pleasantly surprised to see how well the details had been rendered, including the supports for the valve gear and the protruding piston rods, etc.
     
    Further Components
     
    Encouraged by this first trial (which took only 10 mins to print), I continued to select and print the various other components.
     
    I have learned to keep the various parts in the form of individual ‘bodies’ within ‘Fusion 360’, so that I keep as many options as possible open for printing. In this case, the front of the smokebox, shown above, is a ‘body’ in its own right, separate from the rest of the smokebox. The back of this part is completely flat, to lie on the printer bed, while the front has some very fine details, including the piston rods and eccentric rods, protruding from the front surface.
     
    Most of the other parts are simpler and very similar to the equivalent parts on models that I have constructed before. For example, the boiler, smokebox body, and firebox appeared as below, immediately after printing:
     

    My 3D Printed Boiler Components on Printer Bed
     
    I am especially pleased with the way the combined dome/safety valve cover has turned out. I printed this in two parts: the fluted barrel and the curvaceous top cover. I provided each part with dowels and mating sockets, so that they plugged together on top of the firebox. After fitting together, the printed parts look like this:
     

    My 3D-printed Dome/Safety Valve Cover on Firebox
     
    I am reminded of Brunel’s statement in a letter to the engineer T. E. Harrison on 5th March 1838. Forgive the sexist remarks but I am quoting verbatim: “Lastly let me call your attention to the appearance - we have a splendid engine of Stephenson's, it would be a beautiful ornament in the most elegant drawing room and we have another of Quaker-like simplicity carried even to shabbyness but very possibly as good as engine, but the difference in the care bestowed by the engine man, the favour in which it is held by others and even oneself, not to mention the public, is striking. A plain young lady however amiable is apt to be neglected. Now your engine is capable of being made very handsome, and it ought to be so.” [MacDermot, History of the GWR]
     
    I do think this dome is very handsome and has printed very well!
     
    Now, I have all the parts needed to complete the boiler assembly. The major parts all plug together, while the smokebox front is glued to the flat front-face of the smokebox itself. I have not yet attached the weigh-bar and rocking levers, to actuate the valve rods, which can be seen protruding from the front face:
     

    My Model ‘Aeolus’ Boiler
     
    This is a good place to pause before embarking on the running gear, which will support these completed parts. That will be my next post.
     
    Mike
     
     
     
  15. MikeOxon

    After a Pause - 3 plank Wagon

    By MikeOxon,


    general
    I've now built my second GWR 3-planker from a David Geen kit. This time, I made a floor from 10 thou brass sheet, which acted as a template to keep the body panels square. It certainly solved the problem of trying to align several lumps of white metal in my far-from-steady hands!
     
    My method, when working with brass sheet, is to print a scale drawing of the part onto paper and then stick the paper to the brass using a glue-stick. For the wagon floor, I simply used a guillotine to cut out the rectangular shape but this method comes into its own for complex shapes, such as curved frames, when one simply has to follow the lines on the paper template with appropriate cutting tools. Afterwards, the paper is easily removed by soaking in hot water.
     

     
     
    Now, I could assemble the sides and ends, using the floor as set-square and template. The sides have steps at the top of the solebars, on the inside, which provide secure mountings. At the ends, I provided a folded tab, which similarly provided a secure fixing. It was now very simple to align one side and one end - unlike when these parts were 'floating' freely.
     

     
     
    The additional sides were then added and fixed to the floor-plate. In fact, the castings all fitted very well and simply needed the floor as a jig to assist their assembly. This time, I ignored the advice in the instruction sheet and waited to attach the axle guards until after the main structure was complete. This showed up an asymmetry in the castings since, when the guards were centred over the bump stops on one side, those on the opposite side were noticeably displaced, when the axles were lined up correctly. I fitted the guards on one side first and then trued up the axles before gluing those on the opposite side.
     

     
     
    The detail on the castings is very good indeed and once I had found a way of truing up the assembly, I think this makes a very attractive early wagon.
     

     
     
    I am very grateful for all the suggestions that were made on my previous posts and would like to ask one more question. Am I correct to assume that the V-hanger should be removed from the side opposite the brake gear? I guess that there was no shaft across the wagon but that the one-side brake was supported by a single V-hanger and the vertical rod inside the brake rods.
     
    Now for another pause. I read, on another thread, about air brushes and, as a result, have bought an AS186 kit to have a go! It may take some time for me to get the hang of it and, definitely, some time before I have anything fit to post!
     
    Mike
  16. MikeOxon
    The ‘tilt wagon’ seems to have been a popular design in early broad gauge (BG) history but I hadn’t got round to building a model before now. A very few of these wagons were converted to standard gauge and I did model one of those back in 2014, regarding it as an interesting curiosity!
     
    In the early days, it seems that most goods (and 3rd class passengers) were carried in open wagons but a growing need for weather protection led to the addition of canvas covers, known as ‘tilts’ (from an Old English word ‘teld’ meaning tent). Hoops were fitted, to support the canvas, and some wagons had raised ends to provide a more enclosed structure. The late Eddy Brown collected information about these early wagons, which is contained in the Data Sheets available to Broad Gauge Society (BGS) members. A review of early BG wagons appeared in the BGS Journal ‘Broadsheet’ no 34 (Autumn 1995), including the following sketches by J.C.Bourne:
     

     
    Over the following years, many different variants of the same basic style appeared, produced by several makers, of wood or iron construction, most with 4 wheels, although larger ones with 6 wheels were also built.
     
    These wagons became very popular and were used for many different purposes, including carriage of livestock. Evidence of this usage is seen in the lime-washed wagons photographed in the Swindon ‘dump’ after the broad gauge ended in 1892. Overall, the following photograph shows that there was a great range from which to choose, for model-making!
     

    Broad Gauge Wagons at Swindon ‘Dump’ 1892
     
    Several ‘standardised’ wagons, of all-iron construction except for a wooden planked floor, were built in two batches between 1853 and 1854 by various builders. The wagons were generally l7ft. long with side-doors. The inside width was either 9’ 9” or two inches wider. The wheelbase was 9’ 9” in all cases. They had 3’ long springs, set behind the axleguards, with 3’ 6” wheels and Normanville high-filler patent axleboxes. Drawing NRM 4832, below, does not show brakes but they may have been fitted at some stage.
     

     
    This old drawing is rather distorted but there is a better version in Alan Prior’s book ‘19th Century Railway Drawings’. Thus, I had the basis for constructing a model by following my usual method of copying over a printed drawing using ‘Fusion 360’ software.
     

    My 3D-model of an 1850s Tilt Wagon
     
    The chassis was a direct copy of the one I designed previously for my 12-ton coal wagon, of which the prototype was built to the same specification as the tilt wagons of the period. I had to lengthen the ends a little, to match the body of the tilt wagon, but this was a simple adjustment in ‘Fusion 360’.
     

    My 3D-model of the Underframe
     
    Although these wagons used smaller (3’ 6”) diameter wheels than the 4’ wheels of earlier versions, it was still necessary to provide apertures in the floor, for the tops of the wheels to protrude into wheel boxes.
     
     
    Printing my Model
     
    As I reported in my previous post, I am now using a ‘Prusa Mini+’ printer to create my models. As well as learning about the printer itself, I have been learning how to use the associated ‘Prusa Slicer’ software, which has several differences from the ‘Cura’ software that I used previously.
     
    ‘Fine Tuning’ the printer
     
    Fortunately, the printer itself is so smooth and quiet in operation that it seems to encourage experimentation, so I have been trying out various software settings in order to improve the performance, particular in respect of ‘stringing’ and ‘oozing’ of filament, as the print head moves between different areas of the print.
     

    Filament stringing around printed edges
     
    Although, when using my E180 printer, I frequently saw straight lengths of filament along lines where the nozzle had transited between different parts of a model, I have not seen this gossamer-like ‘fluff’ before and shall be interested to receive any comments from others who may have experienced this problem.
     
    It’s fairly easy to remove, by rubbing with fingers and an old toothbrush but, although I have reduced it considerably by adjustments to temperature and retraction distance, I have not yet eliminated it entirely.
     

    Tilt Wagon on Printer Bed before Cleaning
     
    I found that a useful tool for removing the ‘gossamer’, without damaging rivet detail, is a silicone rubber shaper, intended for controlling painted edges.
     

    Artists Silicone Colour Shaper as a Cleaning Tool
     
    Incidentally, during the course of my experiments, I suffered a break in the filament, as it loaded from the spool. The sensor, which I had bought as an optional extra for the printer, immediately detected the break and paused the print. The LCD screen displayed instructions for re-loading the filament and the print then re-started from where it had paused, without a hitch.
     
    Print ‘Quality’ Settings
     
    The layers of print produced by the Mini+ were noticeably more even than those from the E180. This very even-ness, however, made them more noticeable under close examination. At the 0.15mm ‘QUALITY’ setting for layer height, the layers are clearly visible in the close up photos below. There is also noticeable ‘trailing’ of filament around raised details. By changing to the 0.1mm ‘DETAIL’ setting in the slicer software, the printed layers blended together and, perhaps more importantly, the rivet detail was more cleanly defined. There is still a little ‘trailing’ but this is not noticeable under normal viewing conditions. These are unpainted surfaces with no additional surface smoothing after printing, apart from removal of the ‘gossamer’ referred to above.
     

    Close-up Comparison of Two Quality Levels
     
     
    Preparing the Model for printing
     
    I often like to break a model down into separate components, both to reduce individual print durations and to allow optimum positioning of components on the printer bed, to reduce the need for additional support structures.
     
    This particular model presented difficulties in adopting this approach, because there are very few flat surfaces, apart from the floor, while the ‘bonnets’ at the ends have substantial overhangs under the curved canopies at the top. I did initially try printing the sides and ends separately but it proved awkward to assemble the resulting parts neatly, so I thought I would risk printing the body all in one piece and see how well my new printer coped with the overhangs.
     
    I should not have worried, since the body printed cleanly and accurately. This, in the end, was by far the simplest and most satisfactory solution! There was still some fine ‘stringing’ of filament, appearing rather like spider webs between isolated structures, such as the ‘strouters’ (posts) that support the iron sides of the prototype. These fine strands of filament were easy to remove but I am hoping that further adjustments to the printing parameters will eliminate this minor problem.
     
    When I placed two models together, one printed with 0.15mm layer height and one with 0.1mm height, the quality difference is barely visible and would probably disappear under a coat of primer and a final coat of paint. There are still some whiskers of filament that need to be cleaned off before painting.
     

    Two models printed to different ‘quality’ standards
     
    There is a significant difference in the times taken for these two models to print. The 0.15mm resolution print took 1h 30m whereas the 0.1mm resolution tool 2h 40m. Whether this difference is significant depends, perhaps, on the overall size of the model and for small items such as these, I did not feel it was any hardship to adopt the finer quality.
     
    The following picture shows the complete model, with both body and chassis printed at 0.1mm ‘Fine’ quality. I have added wire rails between the ‘strouters’ or posts.
     

    My 3D-Printed Tilt Wagon + Chassis before painting
     
    Mike
  17. MikeOxon

    An Ugly Duckling

    By MikeOxon,


    General
    Having been inspired by a recent post by @Annie, I’m having a go at creating a 3D-print of one of those ‘ugly-duckling’ 4-4-0STs, much liked in the West Country as very successful engines.
     
    As usual, I’m applying ‘quick and dirty’ methods, to create as much as possible by extruding ‘bodies’ from existing drawings – in this case those by Ian Beattie, reproduced in the Broad Gauge Society magazine ‘Broadsheet No.73’
     
    I imported the front-elevation drawing as a ‘canvas’ into ‘Fusion 360’ and used its drawing tools to trace around the outlines of the smokebox and the tanks. I extruded the area of the smokebox to form a 3-dimensional ‘body’ and repeated the same process for the tanks.  My intention was to fit these two parts around a brass tube, which will form the engine’s boiler.
     

    Initial sketch drawn over imported ‘canvas’
     

    Smokebox extruded from initial sketch - Tank also produced by the same method
     
    My next step was to import the drawing of the side elevation and use it to extrude the frames and splashers, as shown below.
     

    Frames extruded from sketch over imported ‘canvas’
     
    Now I had three virtual components to pass to the 3D printer. I used ‘Cura’ software to generate the printer files and this software also creates any necessary support structures. The following screen shot shows the infill that reinforces the internal structure of the tanks:


    Cross-section of Tank in ‘Cura’ print pre-view
     
    Note the information, on the above screen-shot, that the Tank structure takes 1h 29m to print and has a filament cost of about £0.13. The other components took under 30 min each to print.  After printing the three components, I stacked them together, to show how the final assembly could look:
     

    Loose assembly of 3D-printed components
     
    The tank and smokebox printed well but the frames are a little too thin, with very fragile axlebox horns, so I shall strengthen these areas. Because the individual components print quickly, it is easy to make modification on the basis of the trial prints. The brass tube forming the boiler is just visible below the forward part of the tank in the above photo. This part of the assembly is shown more clearly below:
     

    Tank and Smokebox slid over Brass Tube
     
    I think these steps demonstrate the feasibility of designing a locomotive around parts which are simple extrusions from published drawings.
     
    At present, I am trying out my ideas on various locomotive types that I find of interest. Many of my previous models have been based around the South Wales line from Gloucester and I note that four of these 4-4-0ST engines were operated by the short-lived Carmarthen and Cardigan Railway before being sold to the South Devon and Cornwall railways. This allocation to South Wales could be used to justify this type being found together with my other models.
     
    Mike
  18. MikeOxon

    An Ugly Duckling - 3

    By MikeOxon,


    General
    If my last post was about ‘making choices’, the subject of this one is definitely ‘rivets’. These earlier engines seem to have been covered in the things so, thank goodness, 3D-printing software tools have come to my aid in reproducing them all. In fact I only had to draw one or two and all the rest were produced by tools such as ‘pattern on path’ which instantly created long rows of the things, following the contours of the surface on which they are placed. There must be at least 350 rivets on the tank surface alone.
     

    ‘Aurora’ Tank with added rivets
     
    Compare this illustration with the one in my previous post, where I had just completed the basic tank structure! It is the sort of job that could have been a nightmare, when using traditional construction techniques, but was relatively simple with 3D-modelling software – at least with ‘Fusion 360’, by means of its ‘pattern on path’ commands.
     
    I consulted several different drawings and found discrepancies between all of them. A consistent failing was in the width of the outer cladding of the smokebox, which was insufficient to surround the 24” diameter cylinders. I have widened the wrapper around the cylinders, as on many other engines of the period, although this does not appear on the drawings I have.
     
    The cross-section of the tank also varies between drawings although all agree that the tank is wider at the sides than the space above the top of the boiler. This is different from the full length tanks on, for example the Bristol & Exeter engines, where the tanks appear to be concentric with the boiler.
     
    Apart from that, the modelling and printing of the major components has gone extremely smoothly. I thought I might have a printer problem, since the print head was very slow to warm up, when I first used it after a break. My printer is unusual in that the head is part of a separate, plug-in module that contains the head itself, with its heater and thermocouple. I wriggled it a little in its socket and all was well again. I suspect that the heater draws quite a large current, so there will be a substantial power drop if there is any resistance at the electrical connector.
     
    Following my usual practice, I printed the main body of the engine as three major components and a couple of minor ones. The Firebox, Smokebox, and Tank were all designed to fit around a length of brass tubing, which forms the boiler and provides the main structural component of the model. As on the prototypes, one only sees the ‘cosmetic’ outer skin. The two minor components are the backplate and the front of the smokebox.


    3D-printed Main Components
     
    I’ll not go into much detail about the construction of the main components, since my methods have been described in earlier posts. Note, however that I have included a filler cover for the tank and holes to provide mounting points for the chimney, sand-box, and safety-valves cover.
     
    I shall single out the front of the smokebox for some more detailed comments. This small component could easily have been combined with the main smokebox in the 3D drawing but could then prove difficult to print, with my fused deposition printer, which needs a flat surface to start from and no major overhangs. The inside of the smokebox needs to be a clear space to accommodate the brass tube, which forms the ‘spine’ of my model.
     
    The front of the smokebox can be made very thin so that, when laid flat on the bed of my printer, the complete job prints in only about 6 minutes. Once having copied the profile from the cross section drawing that I had used for the smokebox itself, I then added details to the front surface as described below.
     
     

    ‘Aurora’ Smokebox Front
     
    After sketching the outline in ‘Fusion 360’, I extruded the sketch to create a flat plate, 0.5 mm in thickness. Using this surface as my drawing-plane reference, I first drew two pairs of concentric circles to represent the cylinder covers. I also drew one small circle to represent one of the bolt heads and then used the ‘pattern on circle’ to create a ring of 16 bolt heads for each cylinder cover. I find it best to extrude the deepest parts first, so that the drawings for other parts remain visible on the surface. So, I selected all the smaller circles and extruded these by 0.5 mm.  I then selected the annulus between the inner and outer large circles and extruded this area by 0.25 mm.
     
    Next, I tackled the smoke box door. This is made up of a series of three-point arcs and straight lines, to create the outer rim of the door. Then I sketched one of the door latches and used the ‘copy/move’ command to replicate the other catches at the required locations and orientations.similarly, I drew the outlines of the two hinges at the bottom of the door. As before, I extruded the drawings of the latches and hinges by 0.5 mm and the rim of the door itself by 0.25 mm.
     
    For the rivets around the edge, I created a single rivet as a ‘New Body’ at the top of the smokebox front and then used the ‘pattern on path’ command to create replicas all around the edge.  I selected the ‘symmetrical’ and ‘align to path’ options, to spread the rivets evenly in each side and at a constant distance from the edge. The distances that I quote are all the result of trial and error, a process that is greatly facilitated by the very short print times of components such as this.
     
    I made the backplate in exactly the same way, although this is thicker to allow for curved fillet round the edge, which was polished brass in the prototype. I sketched and raised the firebox door and the minimal controls
     
    The end result, with the components all mounted onto a brass tube (visible through the chimney aperture), is shown below:
     
     

    Complete boiler assembly with components mounted on brass tube
     
    Next, I shall turn my attention to designing and constructing a suitable chassis.
     
    Mike
  19. MikeOxon

    An Ugly Duckling – 4

    By MikeOxon,


    General
    Now, wake up at the back there, @Mikkel, this is a new post on this subject.
     
    At the end of my previous post, I wrote “Next, I shall turn my attention to designing and constructing a suitable chassis.”, so that’s the subject for today.
     
    Frames
     
    The frames of these early engines were rather unusual in that they stopped short in front of the leading drivers. The front bogie was attached directly to the boiler in traction-engine style. The frames were also quite light, with sizeable cut-outs between the driving wheels.
     
    Following my usual method, I imported a drawing of ‘Aurora’, originally shown in ‘The Locomotive Magazine’, 1896, into ‘Fusion 360’ as a ‘canvas’. I copied over the outlines of the frame, using the sketch mode, and then extruded the enclosed area to a depth of 1 mm, to form the frame. I used the ‘offset’ command to create a rim 0.5 mm in depth along the top edge of the splashers and then extruded this area a further 5 mm, to form the tops of the splashers. Similarly, I made an offset below the outer edge of the extruded splasher tops, to form the front valance.
     
     

    3D extrusion over imported drawing
     
    Experience has shown me that my printer can cope with this amount of valance overhang, when printed with the design laid flat on its back on the printer-bed. There was no need to create a different frame for the opposite side of the engine, as all I had to do was apply the ‘mirror’ command before printing.
     
    Alignment
     
    The next step was to align the pair of frames at the correct separation and create components to represent the buffer beams and footplate. Rather than do this by measurement, I simply used the ‘move’ tool in ‘Fusion 360’ to align the frames with existing boiler and tank components. Once they were in correct alignment, I sketched rectangles to represent the front and back buffer beams and extruded these to create the appropriate ‘spacers’. At the back of the engine, I also extruded the upper part of the buffer beam forward, to represent the footplate for the crew and support for the firebox end of the boiler.
     
    I find it useful to assemble the various parts in the computer, to check that everything aligns correctly, even though I print them individually. The following screen-shots shows how I designed these parts in ‘Fusion 360’:
     
     

    Additional spacers aligned with Frames
     
    Bunker
     
    Once I had set the correct separation of the frames, the next part to consider was that splendidly curvaceous bunker. I tackled this by first sketching the profile over the drawing that I’d imported into ‘Fusion 360’, as shown below:
     
     

    Extruded drawing of bunker side
     
    I then created two duplicate sides and placed them into their correct positions on the 3D model shown above. I sketched a rectangular backplate and extruded this to form another body that I combined with the two sides. Finally, I used the fillet tool to provide the curved corners between the back and sides of the bunker, to create the overall design shown below:
     
     

    Bunker created to fit onto the existing computer model
     
    Boiler Fittings
     
    Three fittings are needed on top of the engine: chimney, sand-box, and safety valve cover. In the past, I have made a bit of a meal of creating such items but it is, in fact, extremely simply to create circularly-symmetrical objects in ‘Fusion 360’
     
    To take the sandbox as an example, the first step is to sketch the half-profile and then to use the ‘Revolve’ command in the ‘Create’ menu to create solid body.
     
     

    Using the Revolve tool in 'Fusion 360'
     
    I used the same method to create the chimney and the safety-valve cover. I added these parts into their correct positions on the computer model, to complete the assembly, as shown below.
     
     

    'Aurora' components assembled in 'Fusion 360'
     
    Having checked that all the parts fit together, I simply transferred the various parts to the 'Cura' slicing software and printed the resulting files. Most parts only take a few minutes to print.
     
    Bogie
     
    One more component is needed to complete the main features of this engine and that is the front bogie.  In the prototype, the bogie pivots on a central ball-and-socket joint attached below the boiler. I feel that this arrangement would not provide sufficient side-swing for a model engine on practical track curvature, so I have decided to adopt the more usual swinging link method of attachment.
     
    Lessons learned (so far)
     
    I feel that I’ve learned a few more useful techniques with ‘Fusion 360’, such as the use of the ‘Revolve’ command.  I’ve also appreciated the various modes of the ‘Pattern on Path’ command.
     
    Moving separate parts into the correct registration with one other, within my computer, has proved to be very useful for ensuring that everything will fit together when printed.  An overall 'rendered' view of my model 'assembled' in this way within Fusion 360 is shown below:
     

     
    I am now much more aware of the limits set by the fused deposition method of printing. The extruded filament has finite diameter, which sets a limit to the details that can be printed.

    If too small, features are simply ignored by the ‘Cura’ software, so it is essential to check the appearance with the ‘Preview’ option before committing to print. Very tiny adjustments to the computer model can make significant differences to the final appearance.
     
    The software can still tie me up in knots sometimes but I think I’m now better at getting out from them
     
    Printing and Assembly
     
    Now comes the easy bit, once the design has been completed. By printing parts separately, the print times can be very short. I made a list of the ‘Cura’ estimates for print times of the various components:
     
    Tank 1h 2min Firebox 39 min Footplate & Buffer Beam 27 min Smokebox 21 min Frame (each) 19 min Bunker 15 min Chimney, Safety Valve, Sandbox (together) 14 min Backplate 7 min Front of Smokebox 6 min  
    It’s easy to refine the prints, in order to optimise detailing within the limitations of my printer, in view of these short times. Printing individual parts also minimises the need for support structures, by choosing the orientation of individual parts to eliminate these wherever possible.
     
    Printing more at once can be appropriate, once the details are known to be correct, but small print-times encourage ‘trial and error’ improvements.
     
    My current printed set of parts is shown below, after assembly of the individual components. A bogie frame appears in front of the engine itself.


    ‘Aurora’, assembled from 3D-printed components, including bogie frame
     
    The way ahead for this model will now follow conventional lines, adding wire handrails, pipes, and similar details. I have not yet decided about wheels but may consider these in another post. My method for constructing 3D-printed wheels has already been covered in an earlier post.
     
    I expect that here will now be a pause, while I continue through to the painting stage.
     
    Mike
  20. MikeOxon

    An Ugly Duckling – Part Two

    By MikeOxon,


    General
    As I commented to @Mikkel, following my previous post on this project, this bit of modelling was a spur-of-the-moment idea after a fallow period when I was lacking imagination. 
     
    It was triggered by a post on @Annie’s thread about modelling one of the B&ER 4-4-0ST engines but now I’m not sure whether this is the prototype I want to model. While thinking about the possibilities, I came across an appraisal of Broad Gauge 4-4-0ST engines in an early issue of the Broad Gauge Society magazine ‘Broadsheet’ [No.17, Spring 1987].
     
    The ‘Broadsheet’ article pointed out that there were 96 of these engines, all derived from a design by Gooch, originally created to meet an urgent operational requirement on the South Devon Railway, following failure of the atmospheric system. The first two engines, built in 1849 set a pattern for all these engines, in that the leading bogies swivelled on a ball-and-socket joint attached to the bottom of the boiler. The boiler provided the only structural link between the cylinders and the main frames, which terminated at the leading coupled wheels, although some later versions had full-length frames.
     
    In order to help modellers, the article divided the engines into four main groups, as follows:
     
    1. GWR and SDR ‘Short-tank’ Engines : together with the first two by Gooch, there were 27 engines in this category, from many different builders. These engines remained substantially as built throughout their working lives, except for the addition of weatherboards, modified front foot-plating and, it is believed, circular smokebox doors.
     

    SDR ‘Aurora’
     
    2. SDR ‘Long-tank’ Engines : there were 16 engines, widely known as the ‘Hawk’ class, which were initially hired by the SDR from contractors. In 1866, the SDR purchased all these engines and ordered 6 more from the Avonside Engine Co. These later engines had full-length plate frames. A further 4 engines were built in 1872 and 1875, designed to be convertible to standard gauge, although this was never carried out. Two of these engines actually outlived the Broad Gauge, when they were used to shunt BG stock at the Swindon ‘dump’ until 1893


    SDR ‘Hawk’
     
    3. Bristol & Exeter Engines : There were 26 engines in this group, generally more standardised than the SDR engines. Although attributed to James Pearson, the engines followed the Gooch design quite closely but with full-length main frames and a very long (9’ 2”) coupled wheelbase. Access to the footplate on all except the first six was over the top of the rear driving wheels, by means of a metal step-ladder.


    B&ER No.71
     
    4. Oddments : The Carmarthen & Cardigan Railway hired 2 engines of this type, which were all eventually sold to the SDR. The C&CR also had two side-tank 4-4-0 engines which were converted to saddle tanks after sale to the SDR. One 4-4-0ST was built for the Llynvi Valley Railway by Slaughter, Gruning & Co., sold to the SDR in 1868, and converted into a six-coupled machine in 1874. The Vale of Neath Railway operated 9 short-tanked locos, very like the 'Corsair/Comet' types, but with neater, straight-bottomed tanks.
     
    After considering this ‘Broadsheet’ article in some detail, I moved away from the B&ER engines. There are potential difficulties in modelling the step-ladders, which have to clear the outside crank-pins while, at the same time, the valances of the splashers have to clear inside the coupling rods. Taken together, these present a major challenge to clearances in 4 mm scale. Apart from that significant factor, I also dislike the appearance of these engines with their cramped sheet-iron cabs (although these were later removed by the GWR)
     
    On the other hand, I was drawn to the shapely curved sides of the bunker on some of the SDR engines, although some others had straight tops. So, after much deliberation, I decided to have a go at modelling ‘Aurora’ from the SDR ‘Short-tank’ group, precisely because it has so many interesting shapes to challenge my 3D-modelling ability!
     
    The main dimensions, as listed in the RCTS booklet were :
    ‘Aurora’, built Jan 1852 by Longridge & Co, Bedlington wheelbase 17’ 9” (5’ + 5’ 1” + 7’ 8”) coupled wheels 5’ 9” dia bogie wheels 3’ 6” dia boiler barrel 10’ 6” x 4’ 5” dia firebox casing 5’ x 5’ 3” height 14’ 9” boiler pitch 6’ 8”  
    I used the same method that I described in my previous post to extrude the saddle tank from a drawing – this time a pencil sketch by F.J.Roche, reproduced in the ‘Broadsheet article. This drawing was useful for the front elevation but I feel the drawing in Mike Sharman’s compilation by the Oakwood Press is more dependable for the side elevation.
     
    I imported the drawing into ‘Fusion 360’ as a ‘canvas’ and then extruded the length of the ‘short-tank’. I added the downward extensions in the central part of the tank by extruding rectangles and then used the ‘fillet’ tool to produce the rounded corners, as visible on the prototype photo above.


    ‘Aurora’ short-tank extrusion
     
    I was especially pleased with the cut-outs since John Brewer, the author of the ‘Broadsheet’ article, commented that: “These earlier engines had short saddle tanks. leaving the firebox uncovered.  Most had odd and asymmetrical cut-outs in the lower edges of the tanks, which might almost have been purposely designed to thwart the modeller.” Fortunately, the convenient features of 3D-modelling software came to my rescue!
     
    Interestingly, the Longridge-built engines were taken by truck to Gloucester and tried out on the Cheltenham line, so they did fall loosely within the orbit of some of my other BG models, also based in Gloucester.
     
    In his article, John Brewer wrote quite a lot about the difficulties to be faced by modellers of the time (1987) in attempting to create one of these engines. Reading his comments made me sincerely grateful for the advances in technology that have provided me with a 3D-printer!   John also used an expression regarding these engines that I had to look up: he referred to their 'jolie-laide' character which so endeared these machines to the author. Now that I know what it means, I have to agree  
     
    I shall continue to construct my model along the lines described in my previous post – assembling the 3D-printed components around a brass tube representing the boiler. I hope to show more progress before too long.
     
    Mike
  21. MikeOxon

    Another Learning Curve

    By MikeOxon,

    Just as I am deeply immersed in learning about 3D printing and also struggling with the complexities of Broad Gauge locomotive design, along comes a completely new website format.  I've added a little introductory text but, as yet, have no idea how to re-create the contents list, which aimed to help readers to find their way around.
    I'm not sure when/if I shall get around to this additional challenge of learning the new format but, at least, all my earlier posts on how I have tackled modelling problems seem to have come across and will, I hope continue to be helpful to other modellers.
  22. MikeOxon

    Another new 'Old Engine' - 1

    By MikeOxon,


    general
    Since reading Part Three of the RCTS "Locomotives of the Great Western Railway" series, I have become fascinated by the first standard-gauge locomotives to run on the GWR. I shared some of my findings in a forum thread - now updated at https://www.rmweb.co.uk/blogs/entry/26175-early-gwr-absorbed-engines/
     
    My interest has gradually become focused on GWR No.184, which was built by E.B.Wilson and Company for the Oxford, Worcester, & Wolverhampton Railway in 1853. It was photographed several times, showing how it acquired a more modern appearance through at least two re-builds at Wolverhampton works. This engine appealed to me, because it continued in service throughout the rest of the 19th century, ending its life working local trains in the Oxford area, where my current layout is set.
     

     
    There are several problems to be overcome before I can consider building a model of this engine and I intend, in this blog, to document my approaches to solving these. This post is, therefore, the first of what I expect to become a series. I have a "suck it and see" approach to modelling and, at the moment, cannot guarantee that a model will ever see the light of day but I hope that my methods will be of some interest to others. So, to begin at the beginning......
     
    Before starting on a model, I need some reasonable outline drawings to work from. It may be that the originals of No.184 exist somewhere but I am going to work from the information that I have to hand. Part 3 of the RCTS series I referred to above has a line drawing of the original (1853) form of the engine (Fig.C62). It also provides me with the key dimensions of the wheelbase and boiler. While there are photographs of both the 1871 (Fig.C61) and 1893 (Fig.C63) re-builds, there are no drawings of these later versions in these books. There is, however, a drawing of a very similar E.B.Wilson engine, No.192, as re-built in 1874, with later modifications (Fig,C86), so I decided to see if I could adapt this drawing, to provide a fair outline of No.184, as it appeared towards the end of the 19th century.
     
    My usual method, which I have described in earlier posts, is to make photocopies of the drawings and then to overlay them in the computer, to show the similarities and differences. The outside frames were not changed during the rebuilds, so my task was to 'graft' the new boiler and cab from the drawing of No.192 onto the frames and wheels of No.184. In making the overlay shown below, I had to reverse one of the images, since the drawing was of the opposite side of the engine.
     

     
    The overlay shows that the two designs have very similar overall dimensions, so I did not find it difficult to synthesise a single drawing of No.184 from the two overlaid drawings: Both engines had the same overall wheelbase of 15' 6", equally divided in the case of No.192 (when re-built) but 7'6" + 8' 0" for No.184. I was also able to check many details against the various photographs of No.184.
     

     
    Combined with the following information from the RCTS description of the re-built '182 class' :
     
    Boiler Group 35 (Type R3) Code TJ with raised casing:
    Barrel 10' 0" long X 4' 2" diameter
    Casing (firebox) 5' 1" long
     
    Wheels 3' 8" leading, 5' 8" coupled
     
    I believe that there is now sufficient information here, for me to prepare some 4mm model drawings of the engine.
     
    Next job will be to design a matching tender, which is rather more difficult, since there is much less information available, regarding wheelbase and other dimensions, for these early vehicles. That will be the subject of my next post.
     
    Mike
  23. MikeOxon

    Another new 'Old Engine' - 2

    By MikeOxon,


    general
    My first post in this series described how I produced a working drawing for a model of GWR No.184. Now, it's time to consider the tender and, for this, information is less readily available. Wet and windy weather has kept me indoors, so that progress has been rather quicker than I had anticipated.
     
    The various photographs of No.184 show it partnered with a variety of different tenders, so I decided to try to model the tender shown together with its 1893 re-build. I have not found a broadside view of this engine/tender combination, so have had to work from the oblique view shown in my previous post.
     
    In a forum thread on Estimating Dimensions from Oblique Views , I described a technique for correcting the effects of perspective by using the tools in the photo-editing program 'Photoshop Elements' (PSE). This program can adjust the magnification across an image, to correct for the angle between the subject and the camera. Once this has been done, it becomes possible to compare the distances between different points on a photograph, providing these points all lie in the same plane.
     
    In order to use this method on the photograph of No.184, I first identified some parallel lines that are as well-spaced as possible in the image. I chose a line along the top of the boiler and the line defined by the rails below the engine, and marked these in red on the photo, as shown below:
     

     
     
    The next step is to use the 'Perspective' tools in PSE, to distort the image until these two lines are made as parallel as possible,. ( I use an early version of PSE but the principles remain the same in later versions, although the menus may differ in detail.)
     
    First select the whole image (Select | All) and then select 'Transform | Perspective' in the Image Menu. Use the mouse to drag the handles that appear around the image, to offset the effects of perspective by enlarging the more distant parts of the image, as shown below.  It helps to turn 'on' the grid display, when judging when the lines have become parallel.
     

     
     
    Once the image has been 'squared up' in this way, it is possible to compare distances measured along the frames of the engine and tender. The coupled wheelbase of No.184 is known to have been 8 feet, so I used the 'Line' tool to draw a line between the wheel centres, in the plane of the engine frame, and measured the length of this line in pixels. On my image, this length was 188 pixels. I then drew similar lines between the tender wheel centres, which both measured 130 pixels. The 'real' distances between these points are in direct proportion to these lengths, giving an estimated tender wheelbase of 130/188 X 8 feet, or 5' 9" between each pair of axles.
     

     
     
    Unfortunately, the photograph does not show the entire length of the tender, so I could not use this method to determine the overall dimensions of the tender frame. There is, however, a rather similar type of tender, shown behind GWR No. 244, in Part 3 of the RCTS "Locomotives of the GWR" (Fig.C60), which appears to have the same 5' 9" + 5' 9" wheelbase. ( * This is not certain and is based on my assumption that the wheelbase of this re-built engine was 7' 0" + 8' 0" ). This tender scales to 19' 3" platform length.
     

     
     
    I have used the side-on photograph of this tender to produce a line drawing. First, I increased the Contrast of the photo, using PSE, and then selected 'Stylize | Find Edges from the Filters Menu, to produce the rough outline shown below. I used this outline as a template to draw a more refined outline drawing and also included some of the details shown in photos of No.184.
     

     
     
    I adjusted the sizes of both the engine and tender outline drawings, such that 40 pixels correspond to 1 foot on the real engine, and set the scale to 100px/cm, so that they will print at 4mm/foot scale. I then pasted the two drawings (engine and tender) together, to provide an overall impression of the complete 'system' that needs to be modelled:
     

     
     
    Now that I have some scaled sketches, I can start to design the main parts for a model engine. My first step will be to draw, and then cut out, some paper templates, which I shall use to explore a feasible method for construction, and to check clearances for (00-gauge) wheels, motor, etc.
     
    In previous models, I have cut out these templates by hand but, this time, I intend to use my Silhouette cutter.
     
    Mike
     
    Continue to next part
     
    * My assumption is supported by the ratio between the wheelbases being extremely close to 7 : 8. I used a spreadsheet to find that the most precise match to my pixel ratios lay at 6' 10" + 7'10", which would yield a tender wheelbase of 5' 8". The tolerances in my measurements are, however, greater than ± 1" so I have kept my initial estimate.
  24. MikeOxon

    Armstrong Goods - Adding a Tender

    By MikeOxon,


    general
    At the end of my last post, I felt that I had solved all the main problems associated with building my Armstrong Goods engine, although a lot of detailing remains to be done.
     
    To complete the model, I needed to add a tender, which I intended to contain the drive unit. I have made several powered tenders based on 'Hornby' ring-field mechanisms, around which I used components from either plastic or white metal kits. I have used two different 'Hornby' mechanisms: type X9105 with 7' 6" + 7' 6" scale wheelbase and type X2024 with 6' 6" + 6' 6" scale wheelbase. In both cases, only the outer axles are driven, while the centre axle is free running.
     
    There is a very useful overview of GWR Tenders by Jim Champ on the GWR.org website. In this, I read that “The earliest standard-gauge tenders, like the locomotives they were attached to, were a rather motley collection from a variety of manufacturers.” From 1866, however, Swindon-built tenders had iron-plate frames and most had the now standard 6' 2" + 6' 10" wheelbase. 306 were built, typically 1800 gallon capacity.
     

    Typical Armstrong Tender
     
    Note that the overall wheelbase of these tenders was 13 ft, which matches the 'Hornby' X2024 drive unit, in which the centre axle can easily be moved to represent the unequal spacing of the prototype axles. There are many photographs of Standard Goods engines with these tenders, some with or without coal rails but often with remarkably high loads of coal which, in model form, can be used to cover the drive motor! A particularly spectacular example is shown at Widney Manor Station on the Warwickshire Railways website.
     
    I found a drawing of an Armstrong tender at Fig.62 in Russell’s ‘Pictorial Record of GW Engines’, which I used as the basis for my model. There are many differences in detail between different photos but I decided that this drawing was a fair representation of the type.
     
    Whereas my practice in the past has been to prepare my drawings in a 2D program, such as ‘Autosketch’, I decided to try a new approach by using the drawing tools within ‘Fusion 360’, which meant that all my design work was done within the same software package. This proved very successful, as these drawing tools have many features that made it easy to align and replicate the various elements of the drawing. To guide my drawing, I used the ‘Insert canvas’ feature on ‘Fusion 360’ to display a copy of the drawing in Russell, as a background over which I could lay out my own drawing.
     
    By following this procedure, I drew one side of the tender as shown below:
     

    My Drawing of Tender Side in 'Fusion 360'
     
    Drawing all those rivet and bolt heads could have been extremely tedious but the ‘move and copy’ commands in ‘Fusion 360’ made it a lot easier! I drew one short line of rivets and then duplicated these, as necessary, to form long rows or regular arrangements, such as those around the hornguides. A line of five quickly duplicates to 10, then 20, and so on.
     
    Once I had completed the drawing, I could use the ‘push-pull’ tools to raise all the necessary features by appropriate amounts, to create a 3D drawing of the complete tender side. The selection tools make it easy to select many similar feature at the same time, so that these can be raised all together. The resulting 3D model is shown below:
     

    Tender Side extruded from 2D Drawing in 'Fusion 360'
     
    I also continued my method, as used in other models, of designing the complete tender as a ‘kit’ of separate parts that could be printed and tested individually, without involving long print times. Having drawn one side, it only required a single click on the ‘Mirror’ command to create the opposite side
     
    The front and back of the tender were created by using exactly the same methods and all the parts were transferred separately to my ‘Cura’ slicing software to prepare them for 3D printing. Even the long sides only took around 20 minutes to print, so I could make minor adjustments to the drawings without any very long delays.
     
    Once I had printed the individual parts, I could join them together by welding inside the corners with a soldering iron bit set to 210°C. Then I lowered the open box structure over my X2024 drive unit. It proved to be a very close fit and I shall have to re-arrange some of the wiring to pack everything in, within the narrow constraints of the overlays.
     

    Tender Sides fitted around Motor Drive Unit
     
    It is clear that the coal load has a lot of work to do!
     
    A highly visible feature of early tenders was the profusion of tool boxes that they usually carried, either all on the top plate or, in some cases, on a broad shelf immediately above the back buffer beam. In a study of GWR tenders published in the Broad Gauge Society magazine ‘Broadsheet’ vol.18.14, the authors speculated that these extra boxes held locomotive screw jacks.
     
    I 3D-printed a suitable collection of these boxes on a top-plate for the tender, which will also form a base for the considerable ‘coal load’. The two slots, adjacent to the central cut-out for the motor, are to fit over raised strips on top of the motor block. The following photo shows the tender top loosely positioned on top of the tender body, to check the fit of these components:
     

    Tender Shell with Four Tool Boxes & Filler Cap (in primer)
     
    In order both to conceal the motor and provide a base for a coal load, I first wrapped the drive unit in 'cling film'. This was to protect it from water and dust during the following process. I then cut a small rectangle of plaster bandage (‘Mod-Roc’), soaked it in distilled water, and wrapped it closely around the upper part of the motor unit. I laid my printed top plate over the bandage and weighted it down to hold everything in place while the bandage hardened overnight. I only used one layer of bandage since I did not want too rigid a structure but simply a conformal cover that would prove a suitable surface for adding ‘coal’ chips.
     
    Once the bandage had set, I trimmed away all the excess material but left a layer of cling film inside the bandage across the top of the motor. I then painted the exposed surface with dull black acrylic.
     
    The final task was to paint the tender sides and top with two coats of 'Precision Paints' 1881-1906 GWR Green for the sides, Indian Red for the outside frames, and Black for springs and other parts. The final result is shown below:,
     

    My ‘Armstrong’ Tender with base for adding ‘coal’ load
     
    I realise that many people do not like tender drives but there is no reason why my modelling methods could not be applied to any other type of chassis, if I decide to make changes in the future. The more recent 5-pole 'Hornby' motors run a lot more smoothly than earlier designs and I note that ‘Strathpeffer Junction' models list various ‘upgrade’ kits based on the use of CD/DVD motors, although these are currently not in stock. I may try one of these at some stage, to see if they make a significant improvement.
     
    I need to consider the addition of lining and will do this when I complete the detailing of + locomotive. In photographs of the prototypes, the lining always seems quite subdued and I feel that many models suffer from over-prominent lining. I shall probably make my own, using my Silhouette cutter, as described in earlier posts.
     
    Mike
  25. MikeOxon

    Back in Time - 517 class

    By MikeOxon,


    general
    In my very first post in this blog, I mentioned converting an old K's 14xx to a fair representation of a 517 class. Since the 517 was a very variable class, it's impossible to select a 'typical' version - they vary from the earliest tiny saddle tanks, with a short wheelbase, to the final re-builds, which were very similar to Collett's 14xx series. Nevertheless, there were significant differences between even the latest of these engines and the 14xx - most obviously in the cab but also the 14xx has a higher-pitched boiler and longer smokebox. That's why I said a 'fair' representation, since an accurate model would require a complete re-build!
     
    Superimposing drawings of a late 517 and a 14xx, shows both the similarities and differences. In fact, if you 'scale up' the 517 drawing by about 6%, then they become very close indeed, so I comforted myself by thinking that a small difference of scale is hardly noticeable in a model!
     

     
    The K's model is a simple white-metal body casting, which includes plates below the footplate, to carry dummy outside-bearings for the trailing wheels. As I wanted an inside-bearing model, it was simply a matter of removing these parts. The next 'removal' was more difficult, since the front toolboxes on the 14xx model are cast integrally with the front splashers. It needed careful work with a saw to separate these without damaging other parts of the model. Cutting away the cab was relatively simple, leading to the stage shown below.
     

     
    I then made a new spectacle plate from styrene sheet and rear extensions to the tops of the side tanks, in the same way. I cut out part of the original cab sides and fixed them to the new tank tops and spectacle plates with superglue. A new cabroof completed the model -a pretty quick and easy conversion.
     

    Since the original model had a Belpaire firebox, I needed to find a prototype 517 with both this type of firebox and inside-bearings on the trailing wheels. Fortunately, Russell's 'GW locomotives' contains a photo of No. 835 with these key features, so I numbered mine accordingly. With modeller's licence, I decided I also wanted smokebox 'wing plates', since these are a nice 'Victorian' feature and also disguised the drum-type smokebox. To shape these, I took a head-on photo of my model and then scaled and printed this as a template for cutting out styrene sheet.
     

     
    I also needed new sand boxes so, as I have mentioned in another forum, I made these out of the ends of a couple of nylon cable-ties:
     

     
    As I pointed out at the outset, there are plenty of detail errors but I think No.835 takes its place very well alongside my 'Stella' conversion.
     

     
    Mike
     
    addendum - since writing this post, I have started a thread covering the variations within the '517 class' at http://www.rmweb.co.uk/community/index.php?/topic/92797-george-armstrongs-masterpiece/&do=findComment&comment=1668654
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