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MikeOxon

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  1. MikeOxon

    'Cheats' Lining & Lettering

    By MikeOxon,


    general
    I have mentioned before that the attractions of the pre-grouping period include the elaborate and colourful liveries. These also, however, present a challenge to the modeller in achieving these effects on a small scale.
     
    Many years ago, while recuperating from a bout of pneumonia, I built a rake of Ratio 4-wheelers. Looking at these now, I am somewhat amazed to see the patience with which I tackled their painting! 30 years later, natural 'weathering' has given them a 'used' appearance, and I quite like the appearance of the dust on windows and footboards!
     

     
    The Ratio sides have good relief detail, which I exploited when applying the lining. A steady hand and fine brush were all that was needed to apply black to the raised moulding lines. These coaches, however, also had a thin gold line within the edges of the panels and realising this feature was much more difficult! Eventually, I found a technique that, I think, worked rather well.
     
    After completing the main painting, using enamels, I made up a dilute water-based gold paint. (at the time, I used Rowney Poster Paint). I found that surface tension caused the water to accumulate in the recessed edges of the panels, and so deposit a fine line of gold particles in these areas. After drying, it was simply a matter of removing any stray particles with q-tips and a fine dry brush. This method laid down just enough gold to provide the necessary highlight, without being too prominent. I find some model lining is far too dominant, which does not create the right 'impression' of the prototype.
     

     
    Nowadays, there are many tools and materials that were not available 30 years ago. Most significant of these is the Personal Computer, which allows detailed artwork to be prepared, using programs such as Photoshop. I have used my computer to prepare lining and lettering that can then be printed onto specialist materials, such as the various decal papers distributed by Crafty Computer Paper - http://www.craftycomputerpaper.co.uk/category/Decals
     
    I have been pleasantly surprised by the resolution that can be achieved by printing on these papers with an ordinary ink-jet colour printer. I use an HP Deskjet with the print quality set to 'maximum dpi'. As well as printing individual items, I also sometimes print whole panels, such as a wheel arch, complete with edge lining and emblems. These are then applied in the same way as other water-slide transfers. When viewed under a microscope, I find the detail is amazing. The maker's-plate is only about 4mm across and yet most of the lettering can be read.
     

     
    Similarly, the GWR garter crest on the splasher shows plenty of detail
     

     
    I remain, of course, seriously impressed by the skills of those who create these effects with bow pens and rigger or liner brushes, but my 'cheats' do enable good results to be achieved by those of us with lesser skills 🙂
     

     
     
    Mike
  2. MikeOxon
    Readers with long memories may recall that, back in March 2017, I started to think about construction of a Waverley Class locomotive – ‘Rob Roy’. This was a part of a project to build the components of the two trains involved in the Bullo Pill accident of 1868.
     
    My modelling of ‘Rob Roy’ became a test bed for many different ideas – how to build sandwich frames, adapting a brass kit intended for a Goods engine, exploring the working of early valve gears, and so on.  In between, I was easily distracted into simpler tasks, such as building Broad Gauge (BG) carriages.
     

    GWR Mail Train 1868
     
    Then, in early 2019, a revolution hit my modelling world, as I struggled to get to grips with the use of computer-aided design and 3D-modelling. This spurred its own series of experimental projects, including making a model of a Gooch Goods engine ‘Tantalus’, using a mix of traditional brass construction with 3D-modelled parts.
     
    Through all this, ‘Rob Roy’ has taken a back seat, partly because I was otherwise occupied and partly because the main outlines were complete. The fiddly job of adding the small bits and pieces (those bits that are crucial to a ‘good’ model) is all to easy to keep putting off!
     
    I have also considered the thorny question of ‘colour’ in BG engines. The general opinion is that the colour was ‘Holly Blue’ and it was also referred to as Dark Blue-Green. Early copper-based blue pigments, such as Malachite, tended to have a bluish tinge and I began to speculate whether the early GWR colour was actually more like that later used (or continued) by the Wolverhampton works, when Swindon changed to Chrome Green.
     
    I had already used Rustoleum ‘Painter’s Touch’ Dark Green paint for a Wolverhampton locomotive model but it seemed rather light to match the BG descriptions. For ‘Rob Roy’ I decided to try this paint again but with added black pigment to darken the colour.  Whereas the original, lighter colour looked distinctly blue (to my eyes), it seemed to look ‘greener’ as I darkened the mix.
     

    Painted Boiler
     
    I find the result very satisfying and, for some reason, I find myself believing that this is a very appropriate colour for that period.  It has a ‘distinguished’ appearance and sets off the brass-work very well. Others are, of course, entitled to disagree, as reliable evidence is lacking.
     
    One thing leads to another and, once I had applied a couple of coats of paint, I began to think about how to deal with the awkward rounded ‘fillet’ between the firebox and the boiler. This is always a problem when building etched brass kits but I had side-stepped the issue with my model of the Gooch Goods ‘Tantalus’ by 3D-printing the firebox, with the fillet included in the Computer design.
     
    Then I thought, why not simply extract the curved front of the firebox from the Goods engine model and print it as a separate component? The dimensions were already correct since ‘Tantalus’ and ‘Rob Roy’ used the same type of boiler.  I ‘sliced’ the front of the firebox in my computer modelling tool, ‘Fusion 360’ and also cut the resulting ring just below the mid-point of the boiler to leave a horseshoe shape that would clip around and hold itself to the boiler, intermediately in front of the firebox.  Once 3D-printed, I applied a coat of ‘gold’ paint and clipped the fillet into position on the engine.  In my opinion, it looks good and solves an awkward construction problem.
     

    3D-printed Boiler Fillet
     
    After that, I decided to apply 3D-printing to those strange inverted springs between the two leading wheels of ‘Rob Roy’ Although my computer model looked quite good, the detail of the springs was too fine to be rendered accurately by my printer but I think they are adequate for 4mm scale.
     

    3D Printed Spring
     
    As my title indicated, this has been an ‘odds and ends’ post but it got me working on some of the finishing stages of ‘Rob Roy’   There are still many minor items to add, such as buffers, whistles, handrails and the like but I already have the necessary parts to hand and the same additions are required for ‘Tantalus’, so I will tackle them on a ‘production line’ basis  
     
    Mike
  3. MikeOxon

    'Rob Roy' on track

    By MikeOxon,

    I've been putting off cutting out a second set of frames for too long, so have now made a determined effort to finish this task, before the Christmas hibernation period.
     
    Of course, it's always easier the second time and the techniques I'd developed for building frames worked well, the second time around. As before, I printed the drawings that I had made, using Silhouette Studio software, to paste onto brass sheet for use as cutting templates. Once the frames were cut out, I attached strips of 5 thou (0.125 mm) brass and curved these around the tops of the frames to form the splashers, as shown below:
     

     
    I soon had two frames - and even remembered to make them 'handed', for left and right sides! The tabs that I provided made it easy to curve and fit the splasher tops to the inside frames. I had already cut out fronts for the splashers, using brass-effect vinyl, in my Silhouette cutter, and these were glued in place, as before.
     

     
    The next step was to mount the frames at the correct distance apart, so that the boiler assembly could slot in between them (I haven't yet made proper boiler mountings so, for photographs, the boiler is simply resting in place). I decided to use two 1 mm thickness x 6 mm wide brass strips at each end of the frames, to provide sufficient rigidity. I then soldered two strips of thinner (10 thou - 0.25 mm) brass strip to the insides of these bars, with the ends folded up to provide 'tabs' for soldering to the insides of the frames. The completed structure is shown below:
     

     
    The firebox is quite a tight fit between the frames, when sufficient clearance is left for the driving wheels at the correct Broad Gauge spacing, but everything did fit - to my considerable relief. I am considering mounting the leading pairs of wheels in a 'hidden' bogie, so that thy will have some movement to allow the locomotive to negotiate curves.
     

     
    There's still a long way to go before it will become a complete locomotive (and the 'fiddly bits' always take an inordinate amount of time) but I was feeling sufficiently pleased to polish up the brass and pose the engine in its current state on a short length of Broad Gauge track.
     
    My first reaction was to think that the polished brass looked rather garish but, of course, that is what the real thing must have looked like, in the days when pride of appearance was most important
     

     
    May I wish you all the best for the Christmas season and into the New Year.
     
    Mike
  4. MikeOxon

    'Special'- unique photo

    By MikeOxon,


    general
    As I mentioned in the previous post, I have been trying to track down a photo of the prototype of Sir John's special train.
     
    Today, I have found one but unfortunately, the morning of April 1st 1892 was notable for the famous London 'pea-soup' fog.
     
    Despite the photographer's best efforts he has been unable to capture much detail of the train. He has, however, used sepia toning very effectively to enhance the subject 🙂
     

    Train in London Smog - 1st April '92
  5. MikeOxon

    ‘Fire Fly’ class - Research

    By MikeOxon,


    General
    Introduction
     
    One thing leads to another and what, for me, started as a small project to build the interesting-looking ‘Posting Carriage’ from the early years of Brunel’s Broad Gauge railway, for the GWR, rapidly extended to include a Luggage Truck and Horse Box.
     
    All these vehicles appeared in some of the beautiful lithographs by J.C Bourne, published in 1846. In particular, his illustration of Bristol Temple Meads Station, shows an engine of Gooch’s ‘Fire-Fly’ class heading a train including vehicles that I have now modelled.
     
     

    extract from a Lithograph by J.C.Bourne, 1846
     
    Thus, the next step for me was clearly to add a model of this type of engine, in order to create a complete train from the 1840’s period, when railways were on the threshold of transforming the mobility of goods and people throughout Britain.
     
    Background Research
     
    Before starting to create a model, I needed to learn a lot more about the ‘Fire-Fly’ class of engines.  These became famous as the designs by the young Daniel Gooch that transformed the fortunes of the GWR.  The first engines that had been delivered in accordance with Brunel’s specifications had mostly been complete failures, although some became useful after extensive re-building.
     
    Gooch saved the day when he managed to procure the engine ‘North Star’,  which Stephenson’s had to hand from a failed overseas contract.  This engine and its subsequent companions inspired Gooch to create his own design, incorporating new principles that paved the way for ‘mass production’.  He supplied drawings and templates to several different manufacturers, insisting that they conformed to his detailed specifications, so that replacement parts would be common to the whole class.
     
    It was a period of massive development in workshop practice, with engineers like Maudslay and Whitworth introducing methods that allowed accurate machining of components, including such key items as screw threads, to standardised dimensions. A the same time, new metallurgical processes were producing hardened surfaces that resisted wear and tear, so allowing reliable operation of machinery over long periods.
     
    It was these overall design features, rather than individual mechanical innovations that were to make the ‘Fire Fly’ class such successful engines. Brunel’s adoption of the Broad Gauge helped, in that it enabled all the working parts to be laid out in a spacious and easily-accessible manner.
     
    Two reference books in particular proved very useful to me, in finding more details about the ‘Fire Fly’ class: (i) Part Two of the RCTS series about ‘The Locomotives of the Great Western Railway’ provides dates and dimensions of all the engines, with information about their service lives, (ii) a more recent publication by Rev. Canon Brian Arman in Part Two of his survey of ‘The Broad Gauge Engines of the GWR’ contains a wealth of drawings and photographs of the class, throughout its period of use until 1878.
     
    For a contemporary source, Wishaw’s ‘Railways of Great Britain and Ireland’, 2nd ed. published in 1842 contains the following drawing:

     
     
    There is another contemporary description in David Joy’s diary (he later designed the ‘Jenny Lind’ engine) from his early working days in 1842, with Fenton, Murray and Jackson: “… and then got at the interest in the engines. These were Great Western Railway passenger— engines, 16 in. by 20 in. cylinder; 7 ft. wheel. They were a very handsome looking engine, with bright brass dome, and wheel splashers—old fork and gab motion—and I fitted one of these forks, having learnt to file and chip and [he adds] to mash my knuckles with the hammer.”
     
     
    Similarities and Differences
     
    In spite of Gooch’s tightly controlled specifications, there were many differences in detail between the products from the different manufacturers, which affected the overall appearance of their engines. Thus, as so often happens in railway modelling, it is necessary to look at individual engines in order to create an accurate model.
     
    One very obvious difference lay in the shape of the outer firebox cladding (although the internal dimensions were standardised) Some manufactures used a ‘Gothic’ shape with prominent ‘arches’ on each side of the firebox, while others adopted the ‘Haycock’ shape, with a domed steam space above a rectangular lower cladding.
     
    Another obvious difference lay in the position of the manhole cover, provided to allow cleaning of the interior of the boiler.  In most cases, these covers were on top of the cylindrical boiler but, in those engines built by Fenton, Murray, and Jackson, the cover was on the front face of the outer firebox. This distinguishing feature is clearly visible in the engine shown in the Bourne lithograph, above.
     
    Rather surprisingly, these Fenton Murray and Jackson engines also had an overall wheelbase that was 2” (50 mm) longer than other engines. This alteration must surely have been approved by Gooch but the reason is unclear.  Gooch is, however, reported to have said that these engines were the best of the class.
     
    As with most engines, variations soon began to creep in, with various re-builds. Some changes were major, such as conversion to tank engines, while others related mainly to boiler fittings, such as removal of the separate safety valves, originally mounted towards the front of the boilers in tall cylindrical brass casings.
     
    When first built, all the engines used the ‘gab gear’ to operate the valves, which was based on that used by Stephenson in ‘North Star’.


    ‘Gab’ valve gear
     
    By the mid 1840’s the advantages of variable valve gear were being recognised, to allow ‘expansive’ working of the steam, which reduced coke consumption. The Gooch brothers devised their own version of expansion gear and this was applied retrospectively to existing engines, over a period of several years, with 26 engines having been converted by 1849.  Another improvement to the ‘Fire Fly’s was lengthening the piston stroke from 18” to 20”, which seems to have started in around 1844, some of the later engines being delivered new with the longer cylinders. It seems possible that this modification was applied to existing engines at the same time as the replacement of the valve gear.


    Gooch Expansion Gear
     
    In later years, round-top fireboxes were substituted for the ‘haycock’ design and the boilers were extended by about two feet, so that these engines came to resemble the proportions of much later locomotive designs, with cabs and other ‘modern’ features making their appearance!
     
    So, what to choose? I decided to be guided by the Bourne engravings and also by a very clear early photograph of ‘Argus’, which was a Fenton Murray and Jackson engine, as shown below:
     
     

    Fire-Fly class engine ‘Argus’
     
     
    My 3-D Model of the Firebox
     
    My main challenge in designing a model of this engine lay in the shape of the ‘Haycock’ firebox. I puzzled over this for some time, drawing arches in ‘Fusion 360’ and attempting to fill in the panels between them. It possibly can be done in this way but I didn’t find out how, so I eventually settled on a different method, as follows:
     
    I first drew the outline of the base and added an arc quadrant in the vertical plane as shown in ‘Step 1’ below. I then extruded the arc to form a half-arch, as shown in ‘Step 2’ below. Next, I drew a triangle in the horizontal plane below the arch and used the ‘extrude tool’ in ‘cut’ mode, to produce one segment of the ‘Haycock’ top of the firebox:


    Steps in Creating 3D ‘Haycock’ Firebox
     
    After that, it was simply a case of copying the first segment and moving and rotating it, to form the remaining three segments. Once all the parts were in position, I used the ‘Combine’ tool to join the segments of the firebox into a single body. As a finishing touch, I used the ‘Fillet’ tool, to round off the corners.
     
     

    3-D design for ‘Haycock’ Firebox
     
    Measurements of various drawings showed that the ‘Haycock’ tops on the prototypes were a little higher than indicated by my result, based on circular arcs, but this can easily be adjusted in the ‘Cura’ software, immediately before printing, by a change to the vertical scale.
     
    Next Steps
     
    Constructing the firebox top was the main difficulty I had expected to encounter, when designing my 3D-model of a ‘Fire Fly’ class engine.  I am now reasonably confident that I can continue with the design of the remaining parts of the engine, by using the same ‘hybrid’ techniques that I have used previously for my various existing designs, for both the Broad and Standard gauges.
     
    Brass tube for the boiler is now on order from Cornwall Model Boats.
     
    Mike
  6. MikeOxon
    It has taken me a considerable amount of thought before deciding how to proceed with the next stage of building my my ‘Fire Fly’ class model. The obvious method would be to construct a strong frame around the outside, as I have done for previous models, but it doesn’t really work with this prototype.
     
     

    Fire-Fly replica at Didcot showing Boiler Support
     
    As I showed in the previous post, the prototype was built with four short frames linking the smokebox and firebox. Two of these frames can be seen in my photo of the Didcot replica, above. These frames carried bearings for the driving axle and all the ‘motion’. The drag bar at the back of the engine was attached to the rear end of the fire box, The only links between this ‘inner’ structure and the outside frames were six diagonal brackets between boiler, smokebox, and firebox. The role of the outside frame appears to have been limited to distributing the weight of the engine across the two pairs of carrying wheels.
     
    Brass Inner Frame
     
    I decided to adapt this approach to my model, by constructing a strong brass frame that follows the outermost pair of the four inner frames of the prototype, extended to the drag box at the rear of the engine and with a cross member behind the smokebox. This would give me a strong centre-section for the model, with the outside frames being largely ‘cosmetic’. This idea is illustrated below, overlaid on the frame plan of the prototype.
     
     

    My plan for an inner brass frame
     
    I constructed the inner frames from 6 mm x 1 mm brass strip, cut to length, with reference to the frame drawing and soldered into a rectangular ‘box’, as shown below:


    My soldered brass inner frame
     
     
    3D-printed components
     
    I realised as I started to build this model, how much my ideas have changed since I started using my 3D-printer, a couple of years ago. In those early days, it always seemed ‘touch and go’ whether a print would work or not – models detached themselves from the base-plate, filament failed to feed properly and so on, such that I always felt the need to ‘baby-sit’ the process during printing.
     
    Gradually, I learned to adjust the various parameters, to get more reliable printing and much smoother surfaces. A breakthrough occurred when I developed the concept of printing a model in sections, rather like a kit, that would be assembled after printing the various parts. In this way, individual print times reduced from several hours, for a complete model, to less than one hour and, often, around 20 minutes or less for individual parts. This changed my approach to modelling completely, since I could lay out each part on the printer bed, in a way that optimised the print quality. It also gave me confidence to leave the printer to itself, while I enjoyed a coffee break The printer became just another useful tool, rather than something requiring special attention.
     
    The shorter print times encouraged me to experiment with different techniques, before finalising a model. An example of this arose when I printed the footplate for my ‘Fire Fly’ model. The foot-plating follows a rising curve in the outside frames, over the axle boxes for the driving wheels, as shown below, where I have marked out the 3D model over an imported image of the frame plan, imported into ‘Fusion 360’.


    My 3D model footplate, built over an imported drawing in ‘Fusion 360’
     
    According to the ‘rules’, I should provide ‘support’ for this raised section when printing but, since the print time was very short, I decided to take the risk and see what would happen if I omitted these supports.   I don’t like supports, because they can be difficult to remove without damage or leaving traces on the surfaces where they were attached. My temerity was rewarded by cleanly-printed arches    It’s good to try these things, as it helps one to learn the true limits of the printer. 
     
    Splashers
     
    Another recurring problem with modelling early broad-gauge engines lies in producing those close-fitting bicycle-like splashers.  For ‘Rob-Roy’ I fabricated the splashers from brass strip, with Silhouette cut outside faces, finished with gold-coloured foil.  For ‘Tantalus’, I used 3D-printed wheel arches, finished with etched brass facings from the Broad Gauge Society (BGS) kit.
     
    This time, having learned that I could ‘get away with’ some overhangs, I tried 3D printing the entire splasher, laying the back of the splasher on the printer bed and crossing my fingers that the front faces would print, without filling the cavity behind with spurious filament.  Well, it worked very well - just a few individual threads of filament crossing the void, where the print head had traversed from one side to the other. These strands were easily removed to leave remarkably clean prints, as shown below (cruelly enlarged):


    my 3D-printed Driving Wheel Splasher
     
    Considering that each splasher took just 6 minutes to print, I feel that the result was well worth the time spent on this test.
     
    Footplate
     
    I have already described the footplate. It’s sufficient to say that it printed exactly as expected.
     
    Outside Frames
     
    I obtained dimensions for these frames from a sketch in Gooch’s notebook, reproduced in Brian Arman’s book ‘The Broad Gauge Engines of the GWR – Part Two’. I discovered that these sketches are by no means to scale but are a useful source of dimensional information. I chose a different scale drawing to use as a template for building my 3D model in ‘Fusion 360’. This software has a useful feature to ‘calibrate’ an imported ‘Canvas’ from a single known measurement.
     
    Then I followed my usual method of tracing the outlines over the imported drawing (canvas), using ‘line’ and ‘arc’ drawing tools. I then extruded the side frame using the ‘push-pull’ tool in ‘Fusion 360’ and continued to add details, such as rivets, spring and axle boxes, extruding these parts as appropriate. Drawing all those rivets was assisted by using the ‘pattern’ tool described in my previous post.


    My 3D model of Outside Frames
     
    It is worth pointing out that it is not necessary to design separate left and right frames, as the ‘mirror’ command can be used to create the opposite side.
     
    Assembly of 3D-printed parts
     
    I brought together all the separately designed parts on the screen of ‘Fusion 360’, with each ‘body’ labelled separately. Each of these parts could be transferred individually to my ‘Cura’ slicer software and laid out in the optimum orientation for 3D printing.


    Individual Components identified in ‘Fusion 360’
     
    For the record, the print times for each part were as follows:
     
    Firebox – 51 minutes
    Boiler cladding – 45 minutes (not shown above)
    Smokebox – 43 minutes
    Footplate – 23 minutes
    Haycock – 15 minutes
    Outside frame – 8 minutes (2 needed)
    Wheel splasher – 6 minutes (2 needed)
     
    After printing, I assembled the parts together, using a soldering iron set to 200°C to attach the outside frames and the splashers to the footplate. This is a very quick and easy method to fuse together separate 3D-printed components. The smokebox, firebox, and boiler cladding are currently just slipped loosely over the brass boiler tube.
     
    Once assembled around the brass boiler and inner frame, the model so far looks as shown below:
     

    My 1st assembly of 3D-printed components on brass frames
     
    I’m very pleased with the progress so far but there’s still a long way to go. The front of the smokebox awaits details and several lines of rivets need to be added.
     
    There is also the matter of wheels – the prototype wheels had a set of straight spokes alternating with spokes splayed toward the inside of the hub. At present I have no idea how I shall create such a wheel but ‘thinking is in progress’
     
    Then there are the more mundane tasks, such as support brackets, handrails, buffer beam, buffers …
     
    Mike
  7. MikeOxon
    As I carried out my research for this project in Part One (Research), I realised just how difficult it can be to decide what these old engines were actually like!
     
    One of the problems seems to be that, in those days, engines were hand-built by craftsmen who. perhaps, were not so keen on trying to follow a drawing but knew how things should be done!   I noticed, for example, that the shape of the firebox casing on the ‘Fire Fly’ replica is actually quite different from that seen in an early photograph of the original.  I suspect the Didcot team worked to drawings, whereas the original builders did not. The more I looked at old drawings and photographs, the more differences I discovered.
     
    I shall derive as many details as possible from the early photograph of ‘Argus’ that I first showed in my previous post.


    Fire-Fly class engine ‘Argus’
     
    The boilers of these early engines did not rest on their frames in the way more modern designs do but were supported on brackets from the outside frames.   In the case of the ‘Fire Fly’ class, there were also four inner ‘frames’, which were slender bars between the smokebox and the firebox that carried multiple bearings for the long Broad Gauge axles. The ‘machinery’ was laid out in the spaces between these inner frames, as indicated below.


    Fire Fly Frame Plan (from below)
     
    The smokebox, firebox, and boiler seem somewhat lost within the width of the Broad Gauge outside frames. Since my intention was to build these three body components around a length of brass tubing to represent the boiler, this was where I decided to commence building my model.
     
    My Construction Plan
     
    I decided to start from the idea that the smokebox and firebox would be attached to the ends of a brass tube representing the boiler. These two components will be 3D-printed and the boiler itself will be clad by a 3D-printed outer sleeve.
     
    At the outset, I thought that the greatest design problems would lie in the design of the ‘haycock’ cover over the outer firebox. I have already described how I created the shape of this component in my previous post.
     
    Haycock Top
     
    I have added the type of manhole cover that was characteristic of those engines built by Fenton, Murray, and Jackson, such as ‘Argus’, to my existing design of the ‘haycock’ top to the firebox.
     
    I thought it was going to be difficult. until I remembered that, in the 3D computer world, solid objects can happily slide through each other! All I needed to do was to create a small cylinder, tilt it to the appropriate angle and merge it into the haycock body, as shown below:


    My 3D Model with Manhole Cover
     
     
    Lower Firebox,
     
    The lower firebox is essentially a rectangular box, stretching upwards from the ash-pan to the base of the ‘haycock’ top. The sides of this box carry vertically-planked lagging, while the front has a circular opening at the junction to the boiler tube.
     
    I created the appearance of vertical planking by drawing a series of narrow rectangles, to represent gaps between the planks, on each side of the box and used the ‘push-pull’ tool in Fusion 360 to recess these by 0.25 mm.
     
    The circular hole for the boiler was a little more difficult, since the top of the boiler connects to the sloping front surface of the ‘haycock’. I joined together the 3D models of the upper and lower fireboxes in ‘Fusion 360’ and then set up a vertical construction plane, parallel to the front face of the lower section. By using this as the reference for the ‘hole’ tool, I could extend the hole through the sloping top of the ‘haycock’ as well as through the lower box. I then separated the two parts again for the actual printing.


    My 3D- Model of Firebox
     
    Smoke Box
     
    I drew the front elevation of the smoke box with ‘Autosketch’ and imported the drawing into ‘Fusion 360’, where I extruded it to the appropriate length. I intend to create the details of the front, with its door and rivets, on a separate overlay. The three parts, as designed in ‘Fusion 360’, are shown below:
     
     

    My 3D-models for Boiler End Components
     
    Boiler Cladding
     
    At first, this proved easier than expected, since I had already designed the cladding for my Gooch Goods boiler. All that I needed to do was to re-scale the cladding, to suit the ‘Fire Fly’ dimensions, using the ‘scale’ tool in ‘Fusion 360’    BUT … what about that wooden cladding?
     
    Fortunately, I found the answer in another of the series of excellent videos by Lars Christensen from ‘Autodesk’.  This one is about How To Use The Pattern Function and the relevant bit for me starts about 20 minutes from the beginning.
     
    It turned out that all I needed to do was to draw one plank along the side of the boiler cladding and then select ‘Pattern’ from the ‘Create’ menu.  There are options for ‘rectangular’ or ‘circular’ patterns.  I chose ‘circular’ and, after selecting my single ‘plank’, I then selected the outer surface of my cylindrical boiler-cladding. and increased the ‘quantity’ until I had a whole array of appropriately spaced ‘planks’.
     
    This proved far easier than I had anticipated and is a very powerful feature of ‘Fusion 360’. I expect that this ‘pattern’ tool will also be very useful for adding arrays of rivets and the like.  I must acknowledge that it was @Timber who first drew my attention to the ‘pattern’ tool in ‘Fusion 360’, when he commented on one of my earlier posts.


    Creating the Wooden Cladding
     
     
    Assembly
     
    After printing the various components, assembly is simply a matter of sliding the printed smokebox and firebox onto the ends of the length of brass tube representing the boiler. I have shown the printed boiler-cladding separately, so that the brass tube, which gives rigidity and weight to the whole assembly is visible:
     
     

    Boiler Tube with Cladding
     
    Once I had fitted together the various parts , the complete boiler assembly appears as shown below:


    Main components of my Boiler, Assembled
     
     
    Next Steps
     
    These assemblies were all initial test-prints and I expect to add more details in due course, including an overlay for the front of the smokebox and lots of rivets
     
    It’s good to feel that this project is now well under way
     
    I now need to start thinking how to tackle the underframes and how to incorporate brass parts for additional strength. There is so much space between the outside frames of these Broad Gauge engines that I feel it necessary to include more details of the motion than I would do on a standard-gauge engine. I hope that 3D- printing will be a help in producing the necessary components,
     
    Mike
     
    I created the ‘header’ illustration from one of J C Bourne’s lithographs, using the Dynamic Auto Painter software.
     
    Edit: replaced last photo with improved 2nd. print.
  8. MikeOxon

    ‘Rob Roy’ Re-Framed

    By MikeOxon,


    General
    Six years ago, in June 2017, I embarked on scratch-building a model of the Broad Gauge ‘Waverley class’ engine ‘Rob Roy’. The prototype was involved in an accident near Bullo Pill, where some of my wife’s ancestors were working for the GWR at the time.
     

    ‘Rob Roy’ – Accident near Bullo Pill, 1868
     
    I took advantage of the fact that the boiler used for the Waverley-class was the same as that on the Gooch Standard Goods engines, for which the Broad Gauge Society (BGS) provide an etched-brass kit.. My old series of posts described in sometimes graphic detail how I constructed the kit, which involved rolling a boiler from rather thin brass sheet.
     
    After completing the boiler from the kit, I was then faced with scratch building the chassis, which I also constructed from brass sheet.. The process was not without its problems, especially when fabricating the bicycle-style splashers over the large driving wheels but, after much trial and error, I ended up with a passable model.
     
    One major compromise, however, was that I used wheels supplied by Hornby for their ‘Lord of the Isles’ model.  I chose these because they have the required 24 spokes and these exposed driving wheels create a large part of the ‘character’ of the Waverley-class engines. Unfortunately, the wheels are over-size and this not only means they stand a little too tall but also that they had to be more widely spaced than on the prototype. At the time, I felt I had to live with the compromise but now that I have the means to print my own wheels, I felt I should try something better.
     

    My first scratch built model of Rob Roy, with Hornby driving wheels
     
     
    Enter my 3D-Printer
     
    The advent of 3D printing completely changed my approach to model building and I realise that there’s now no need to undertake the tricky fabrication of splashers from brass sheet and nor do I have to cut out the profiles of the sandwich frames by hand.
     
    All I had to do was find a suitable drawing – I chose the one by E.W. Twining – and trace over it in ‘Fusion 360’ before extruding the drawings into 3D structures. My methods have been amply described in earlier blog posts but one of the important lessons I have learned is that it is possible to extrude the valances around the outer rim of the splashers without the need for any additional support during printing. This method worked successfully on my ‘Firefly’ model  and I applied it again here.
     

    Extruded Frame over Twining 'Canvas' in Fusion 360
     
    I then created a mirror image of this first frame and separated the frames at the appropriate distance, linking them be means of a buffer beam and drag bar, as shown below (rendered in Fusion 360):
     

    3D model of chassis, rendered in Fusion 360
     
    As on my previous model, I filled the open space under the front of the boiler by adding a motion plate and ‘suggesting’ part of the motion. Further back, any underpinnings are hidden by the sandboxes and splashers.
     
     

    3D model of chassis with motion plate added
     
     
    Printing the Components
     
    The next step was to pass the various components to the Cura slicing software and then to my 3D printer, which created the following components:
     

    3D printed chassis components, together with my boiler assembly,
    constructed from a BGS etched-brass kit
     
    Once assembled, the chassis looks as shown below, with the boiler supported by the curved motion plate. An advantage of designing the model in ‘Fusion 360’ is that the ‘fit’ of all the parts can be tested before committing them to print. This was especially valuable for this model, in view of the tight tolerances between the splashers and the driving wheels. Note that, as in the prototype, the hind wheels are flanged but the forward pair of drivers are not.
     

    3D-printed Chassis and Wheels after assembly
     
    Although I had felt reasonably content with my original fabricated chassis, mainly because I was unable to improve on the over-size wheels at the time, I realise now how ‘wrong’ it looks, when placed together with the 3D printed version!
     
     

    My original chassis in front of the 3D printed version,
    carrying my original brass boiler assembly
     
    Overall, 3D-printing this chassis was a lot easier than using traditional methods, now that I am reasonably familiar with the ‘Fusion 360’ software. Of course, it is an option that was simply not available to me when I built my first model.
     
    Now I have to add the brass finishing to the splashers and valances.
     
    End of an era
     
    This is probably the last model that I shall print with my ‘Geeetech’ E180 printer. It has given a few problems recently, first with the feed mechanism and now the hot-end temperature has become erratic. This printer uses a modular print-head, specific to this model, and Geeetech have informed me that replacements are no longer available.
     
    After some thought, I’ve decided to buy a Prusa Mini+, partly because I prefer to buy a European product (although I have no complaints about the Geeetech company). I shall report my impressions once I receive the new printer.
     
    Mike
  9. MikeOxon

    ‘Sir Watkin’ for Bullo Pill

    By MikeOxon,


    General
    As the end of another year approaches, I’ve been looking back over the last few rather strange years, very much influenced by the Covid-19 virus. As it happens, 2019 was also the year when I acquired my 3D-printer and embarked on a new phase of model-making. Lock-down provided me with ample opportunity to practise 3D-model making.
     
    A couple of years before that, I had moved my attention to the Broad Gauge era of the GWR, following the discovery that several of my wife’s ancestors worked for the railway over many years. The family arrived at Soudley, in the Forest of Dean, in the early 1850s and the sons started their railway careers at Bullo Pill in the early 1860s. They were there at the time of a serious accident, when a Mail Train ran into the back of a slow-moving Cattle Train. That event inspired me to start modelling the various vehicles described in the BoT Report on the Accident.
     
    More information about the family emerged from their GWR employment records and, from one of these, I learned that my wife’s Gt. Grandfather was involved in a collision between two engines of the ‘Sir Watkin’ class, as described in his record:
     

    Extract from GWR Employment Record
     
    This is the only record I know of any of these engines being used in the Gloucestershire area. The ‘Sir Watkin’ class were originally built as condensing engines for use on the Metropolitan Railway but they were moved when the gauge was narrowed. Later, when all the lines west of Gloucester were narrowed, they were transferred to the South Devon Railway, where they were converted into more conventional saddle tanks.
     
    There are few photos of these engines in near-original condition, although ‘Miles’ was photographed, still with its large side tanks but after removal of the condensing apparatus. I have ‘colourised’ this photo, as shown below:
     

    Sir Watkin class engine ‘Miles’
     
    I found that I have some rather low-quality drawings of these engines in my collection but cannot remember where I found them. I had considered building a model some years ago but decided at the time that it lay in the ‘too difficult’ box. Having gained some familiarity with 3D-drawing and printing, I decided that I was ready to make a fresh attempt.
     
    When I looked at the boiler dimensions, I realised that they were very similar to the Gooch Standard Goods, which I have already modelled, so I started my design by opening my earlier model of the Gooch Goods in ‘Fusion 360’. I also imported my drawings of ‘Sir Watkin’ as a ‘canvas’, which confirmed that the existing parts could be re-used with only minor modifications.
     
    I still need to create a new chassis and to re-design the front of the smokebox and add side tanks and a coal bunker. The smokebox doors were particularly unusual in comprising a pair of rectangular doors, rather resembling oven doors, as seen in the drawing below:
     

    Sketches of 'Sir Watkin'
     
    I added the new parts to my existing Gooch Goods components, using my well-tried methods of extruding them from the 2D drawings. The chimney, dome, and safety-valve cover were all created by using the ‘Rotate’ command in ‘Fusion 360, as described in an earlier post.
     

    3D-modelled parts for my ‘Sir Watkin’ model
     
     
    Exploring new Modelling Techniques
     
    Over the last couple of years I have had plenty of time at home, under Covid restrictions, to develop my simple use of extrusion, to create 3D models from 2D drawings. I felt that it’s now time for a new challenge, by exploring some of the slightly more advanced features of the ‘Fusion 360’ software.
     
    A suitable challenge was presented by the pipework associated with the condensing apparatus originally fitted to the ‘Sir Watkin’ class. I have a sketch of the front-end, showing how the exhaust pipes could be diverted to direct steam into the side tanks, where it would hopefully condense. In early trials on the Metropolitan Railway, it was soon found that the water in the side tanks rapidly approached boiling point, so the method was not very successful!
     


    Condensing Apparatus Dwg
     
    There is a tool in ‘Fusion 360’ called ‘Sweep’, which can move a profile (such as a drawn circle) along a path, drawn by using the sketch tools. It wasn’t immediately obvious to me how to use this feature but I found a useful tutorial called ‘Getting Started with the SWEEP TOOL in Autodesk Fusion 360’ on the web, which soon got me started. As this tutorial shows, it’s possible to construct a huge variety of curved shapes by using this tool and I felt that it opened up new avenues for my own model-making, extending beyond simple linear extrusions. All the examples in the video, however, only showed paths that were confined to a single plane, whereas the pipework on this engine needed pipes curved in two different planes.
     
    My first attempt was to make two half lengths of pipe and after creating two curved sections as separate bodies, I could rotate one with the ‘move’ tool and then use the ‘join’ tool to combine the two bodies with their curves in different planes.
     

    My 4 steps to create a double curved steam pipe
     
    After joining the two sections of pipe into a single body, I moved the steam pipe and a mirror-image copy into their appropriate locations on the 3D-model of the engine.
     
     

    3D drawing of steam pipes in Fusion 360
     
    This provided a method to create the pipes I wanted but it also made me want to explore the apparent limitation caused by only sketching paths in one plane. So, I set off on another learning exercise.
     
    3D Drawing in ‘Fusion 360’
     
    Fortuitously, I found another training video on 'YouTube' entitled ‘How to Create a 3D Sketch in Fusion 360’, which looked like the breakthrough I needed!
     
    It’s actually very simple but requires two options to be enabled in ‘Fusion 360’. First, in ‘Preferences’, under the ‘Design’ tab, the ‘Allow 3D sketching of lines and splines’ checkbox needs to be ticked and, second, when entering the ‘Create Sketch’ mode, the ‘3D Sketch’ options needs to be selected in the ‘Sketch Palette’. I assume that these options are not enabled by default because the resulting appearance on the screen can be very confusing, if you do not actually need the facility!
     

    Drawing tools in 3D sketch mode
     
    This capability to sketch in 3D provides more food for thought, when planning future models.
     
    3D Printing vs Modelling
     
    Another consideration to be borne in mind is whether a 3D model can actually be printed on a particular type of 3D printer. My Fused Deposition Printer (FDP) builds up a solid model by adding successive layers of plastic filament. There always has to be something underneath the point at which current deposition is taking place. So, for example, the printer cannot ‘bridge’ across large openings in a vertical wall, such as window frames.
     
    In view of these limitation, I try to lay out the parts of my models in such a way that there is a flat surface on the printer bed, above which the main body of the model rises with no significant overhangs. That option, though, is simply not available when I look at my steam pipe, which is curved in two planes! There just aren’t any flat surfaces from which to start.
     
    The answer is to use support structures, which the ‘Cura’ slicing software can generate automatically, with a choice of parameters, such as density and thickness of the support structures. I had to try a few options before I settled on one that worked reasonably well on my pipes. Fortunately, each print only takes about 10 minutes, so it doesn’t take too long to discover if the result is an amorphous blob of plastic! In addition to supports, I found that the model needed a ‘raft’ to start from, so that the structure was firmly anchored to the Printer bed. After making my choices, the preview screen in ‘Cura’ looked as below. The actual print looks a little messier, since the printer does not suppress the transits between the support lines:
     

    My method of 3D-printing a curved steam pip
     
    I will admit that I made this pipe as a design exercise and 3d-printing may not be the best method for creating pipework of this type.
     
    Bonsai Wire
     
    An alternative would be to use ‘Bonsai Wire’, to which my wife, an enthusiastic plant-grower, introduced me. Bonsai wire is made from annealed aluminium, which has been coated in copper for the colour. It is available in a large range of diameters and has the virtue that it is easily bent to a chosen form and then holds its shape. I have used smaller diameters for pipework on some of my other models and it could well be applied here.
     

    Bonsai Wire
     
    After printing all the separate components, I assembled my model as shown below. The side tanks and bunker are glued to the footplate, while the firebox, boiler, and smokebox are threaded over a length of 18 mm diameter brass tubing and are simply resting in position. The chimney, dome, and safety-valve cover were printed separately and glued into position on plinths that I provided on the relevant components. The 3D-printed steam pipes are only ‘tacked’ in position, as they need to be easily removed when I dis-assemble the components for painting. I’ve not decided yet whether to add any form of cab.
     
    Some of the printing is a little rough, especially around the boiler, so I shall probably try re-printing to improve the surface finish. Other parts have come out well.
     

    My 3D-printed ‘Sir Watkin’ model
     
    Old and New Comparison
     
    I have mentioned before that one of my objectives in modelling 19th century prototypes is to gain a better understanding of their proportions, in the context of more recent (and more familiar) vehicles. As an example of such a comparison, I show below my model of a Broad Gauge coal wagon against a more modern type of standard gauge wagon. I like to make these comparisons.
     

    Broad and Standard Gauge Comparison
     
    Mike
  10. MikeOxon

    "Read Me First"

    By MikeOxon,


    general
    (the following explanation is intended to help any new readers to find their way around this blog)
     
    Since I started this blog in 2013, I have used it as a diary to record my progress in creating a Victorian GWR branch line. Since the blog follows the meanderings of my mind, it has no real structure and this 'introduction' is, therefore, an attempt to help a new reader to find his/her way around.
     
    There are two main strands: firstly, the documenting of my exploration of the construction techniques needed to create 19th century locomotives and stock, of types that are not readily available. This includes descriptions of how I have constructed kits and also developed some 'scratch-building' methods, including home-made lettering and lining.
     
    The second strand describes the creation of a local scene, which includes the buildings and landscape features and, equally importantly, the personalities who determined what services were needed from a railway serving the local area.
     
    My 'train set' started many years ago as a Hornby Dublo layout for my then young son. The plan was taken directly from the Hornby Dublo Handbook of 2-Rail Track Formations (1st edition) and I added a narrow-gauge (009) section for additional interest. This has evolved into the plan shown below:
     

    Layout Plan with Vignettes
     
    A 'back story' has gradually evolved, in which my layout has come to represent North Leigh station on a never-built branch from the Cotswold main line towards Witney (planned in 1849 but never executed). This fictitious line diverged from the Oxford, Worcester & Wolverhampton Railway, near Stonesfield, and then headed southwards, through North Leigh, to Witney.
     

    1849 Map showing unbuilt line to Witney
     
     
    My layout represents a junction, just outside North Leigh station, where the line from Witney emerges from one of several short tunnels along this hilly route, with a cut-off route towards Worcester, diverging through a narrow cutting, while the original Oxford line enters the station, where there is also a passing loop. Two sidings serve the local creamery and a cattle dock.
     
    The narrow gauge section represents an equally fictitious system, serving the local stone quarries and a saw-mill, which brings traffic to an interchange with the main line at North Leigh.
     
    As well as imagining the railway, I have also devised a number of local characters to populate the scene. There is a real manor house at Wilcote, with mediaeval origins, where I have created a fictitious Victorian family, including the Lord of the Manor: Sir John Wilcote, and his daughters Amy and Blanche, and (probably) a younger son: Charles. Other characters will no doubt appear as I establish further details of the scene.
     
    The 'contents list' at the right-hand side of the blog provides some guidance to the various topics that I have covered so far.
     
    Mike
  11. MikeOxon

    1837 Carriage

    By MikeOxon,


    General
    I.K. Brunel wrote the following, in a letter to T. E. Harrison on 5th March 1838: “... 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.”
     
    My own models of early GWR engines are no more than ‘ornaments’ but, as such, have given me a great deal of pleasure. They have led me to take a greater interest in those very early days of the railway and its hesitant progress through the many set-backs experienced at the time. Members of the Broad Gauge Society (BGS) may have read my brief accounts in that society’s recent Newsletters.
     

    Four ‘early’ GWR Engine Models
     
    The GWR was conceived initially as primarily a passenger-carrying enterprise so, after the engines, the first vehicles needed were carriages for first and second class passengers. At that time, there was no concept that ‘ordinary’ people had any need to travel any distance from their own towns or villages. The model for these early carriages was the road-coaches of the time and, indeed, one of Brunel’s justifications for his ‘broad gauge’ was that it would allow large wheels to be placed outside the main body of the coach, as in the case of contemporary stage coaches. This was quickly found to be impractical, since large wheels blocked the entrances to the compartments, but the overall construction methods initially followed road vehicle principles.
     
    I decided to make a model of one of the earliest types of 2nd-class carriage, to help me appreciate the differences between it and later designs. The most obvious distinction is, of course, size but it is clear that the dynamics of railway vehicles was not understood at the time and the choice of a 6 foot wheel base for a vehicle intended to run at speed on 7 foot gauge track seems unfortunate, to say the least! It is hardly surprising that the rough riding of these carriages caused sufficient concern for them to be ‘ordered off the line’ following a Board Meeting on 12th July 1838.
     
    In creating my model, I followed my usual practice of extruding the various components from a reference drawing – in this case, Data Sheet 102 from the BGS.
     

    Creating my 3D model in ‘Fusion 360’
     
    I have often advocated breaking a model down into smaller parts, to reduce the time needed to print each part so that any necessary corrections can be applied quickly. As in most things, it is best not to be dogmatic about this, especially in the case of a small model like this carriage, where the overall printing time is quite short anyway.
     
    In fact, I discovered with this model that printing the body in one piece produced a better surface finish than was obtained by printing the sides and ends separately. This may be down to the settings I use with my printer but the sides that I printed flat on the printer bed showed much more surface grain than those printed upright, as shown in the examples below:
     

    Sides and Ends printed flat on Printer Bed
     
    The time taken to print the above set of parts was 56min.
     
    For comparison, the time taken to print the complete body was only 1h 32min, including internal partitions between the compartments, which resulted in a rigid structure with a fine surface finish. I printed the chassis separately as shown below:
     

    Body Printed in One Piece above Separate Chassis
     
    In this case, printing the sides separately would be a poor decision, as the time saved is insignificant and the surface finish is poorer – and there is the additional need to align and assemble the various components after printing.
     
    Early Carriages in Context
     
    Another member of the BGS brought to my attention the historical engineering collection held in the National NetworkRail Archives  Amongst them, I found a rather perplexing set of drawings of Maidenhead Depot. When the first section of line opened to the public from Paddington, the original terminus was on the East bank of the River Thames near Taplow, where the bridge across to Maidenhead had not yet been completed. According to James Wyld’s ‘Great Western Railway Guide’ of 1839:
     
    “The Great Western Railway Company have a considerable station here, 42 feet above the level of the London depot, with engine-house, police station, and the usual offices. There is a jail for debtors and felons. The principal trade is in malt, meal, and timber, and the passing traffic derived from the Great Western road and the railway”
     
    All this seems to have disappeared, once the bridge across the Thames was completed, but the Archive drawings include one of foundations for what appears to be a carriage shed, with a central traverser to serve several bays. There is also a base for a small turntable, with a note on the drawing stating “This Turnplate to be carried as far West as the Solid Ground will allow”. I assume that this refers to the embankment leading to the yet-to-be-built bridge across the River Thames.
     
    Out of interest, I took this drawing (Ref.NRCA161489) and used ‘Fusion 360’ to create a 3D rendering, as shown below. I added some of my 1837 carriage models, to show how well they would have fitted within the planned structure.
     

    3D Model of Carriage Shed Foundations with 3 Carriages
     
    Whether this shed was ever built is open to conjecture since these early carriages did not last very long.
     
    Rapid Carriage Development
     
    One of the reasons why I like to build these early vehicles is so that I can use them to demonstrate how rapidly the designs evolved as they began to move away from their road-coach origins.
     
    Sometimes, there seem to have been backward steps before ideas moved on towards our modern concepts. For example, according to Whishaw ‘The Railways of Great Britain and Ireland’, 1842, the GWR rapidly abandoned the use of closed 2nd-class carriages, in favour of open sides, because they were thought to detract from the numbers paying for 1st class!
     
    Here are my models of the 1837 carriage next to the slightly later ‘open’ 2nd, showing the overall increase in dimensions, together with the use of six wheels.
     

    My models of ‘closed’ and ‘open’ 2nd class carriages
     
    The difference in scale, when compared with more ‘modern’ practice (in my context, the late 19th century!), was really brought home when I placed my model 1837 carriage alongside one of the well-known Tri-ang GWR clerestory models!
     

    My 1837 model against a ‘00’ Tri-ang Clerestory coach.
     
    Mike
  12. MikeOxon

    25 years later - ‘Rocket’

    By MikeOxon,


    general
    Having gone right back to 1804 with Trevithick’s locomotives, I decided to start moving forward again - to Stephenson’s famous ‘Rocket’, which was to put passenger-carrying railways firmly on the map.
     
    When I built my Trevithick model, I wanted to put it alongside a model of ‘Rocket’ to illustrate the progress made over 25 years but, although I know I have a 4 mm scale model built from an Airfix kit, ‘somewhere’, I couldn’t find it!
     
    I did find however that there is a 3D printable model of ‘Rocket’ on the same Printables website, where I had found the Trevithick 3D model files. Again, the ‘Rocket’ model was designed for a larger scale than my usual 4 mm/foot but, in this case, the scaling factor needed was not so great.
     
    The model I downloaded was by Václav Krmela, who has made his .stl files available under the Creative Commons (4.0 International License) Attribution-NonCommercial   His model was designed for 1:32 scale, so needed reduction by 42% to print at 4 mm/foot.
     
    Most of the parts printed satisfactorily at the smaller scale but, as with the Trevithick model, I had to thicken the walls of the boiler and chimney to make them sufficient robust. I particularly liked the way in which the design incorporated location tabs, which made it very easy to assemble the printed parts in their correct orientations. For example. I show the basic chassis which has tabs to locate with both the firebox and boiler:
     

    Components of Václav Krmela’s model, showing helpful tabs
     
    These tabs worked perfectly well on my reduced-size prints and are a feature I must aim to include in my own future models.
     
    A feature I didn’t like was that the cross-heads on both sides of the engine were fixed in the same position, so didn’t allow for ‘quartering’ of the driving wheels. When I imported the relevant .stl files into ‘Fusion 360’, however, and converted the mesh bodies into ‘base features’, I found that they split into two parts – the piston body and the piston rod and slide bar – so I was able to re-position the cross heads to appropriate positions along the slide bars. This was unexpected and a feature that must have been ‘lost’ when the .stl files were created!  I have found that the ability to import .stl meshes and convert them to ‘base features’ in ‘Fusion 360’ is very useful, as it allows modifications to be made to downloaded model files.
     
     

    Bodies created in Fusion 360 from original .stl file
     
    To check the overall assembly, I brought all the parts together within ‘Fusion 360’, as shown below.
     
     

    Vaclav Krmela’s mesh model, assembled in ‘Fusion 360’
     
    So now, all I had to do was print the parts. I printed some of the smaller parts in groups, including a set of wheels and a set of various small pipes, rods, and stays. The latter group was on the borderline of what is possible at my chosen scale and I made several attempts before I managed to print a reasonably ‘clean’ set. These tiny parts only took 1 minute to print but adhesion to the print bed was rather ‘hit and miss’ until I tried applying some ‘Pritt Stick’, which increased the success rate considerably – here’s a set, as printed, warts and all:
     

    3D printed pipes, rods, and stays, before fettling
     
    I attached these fragile parts by applying a touch of a 200° soldering iron tip  while holding the ends in place with fine tweezers.
     
    It has been an interesting print job although, looking at the assembled model, the pipework in particular is rudimentary, when compared with the full-size replica. A very significant omission is the pair of pipes carrying exhaust steam from the cylinders to the base of the chimney – this use of the exhaust blast to ‘draw’ the fire was an important factor in the success of Rocket at the Rainhill trials.
     

    Full-size Rocket replica at Tyseley, 25 June 2011
     
    I felt I had to rectify this omission, so I made 3D prints of the two upper pipes and the pipe at the bottom of the firebox. Again I used ‘Pritt Stick’ to ensure that these tiny parts didn’t wander on the printer bed.
     

    My additional 3D-printed pipework
     
    Printing this model has served my purpose in providing a comparison to the Trevithick model, so demonstrating the progress made over the intervening years. The appearance of the ‘Rocket’ model does suffer, though, from the ‘Tri-ang’-like profile to the wheels!
     
     

    3D prints of the downloaded Trevithick and Rocket models
     
    Whereas Trevithick conceived his engine as a ‘general purpose’ machine, ‘Rocket’ was built to meet the very specific requirements laid down for the Rainhill Trials. In particular, ‘Rocket’ was designed to haul light loads at high speed and Stephenson realised that, for this task, adhesion weight would not be a critical factor.
     
    Nevertheless ‘Rocket’ needed improvement for general service use, so there were further rapid developments by the Stephenson company. The next step was the ‘Planet’ class 2-2-0, which introduced the use of a pair of inside cylinders under the smokebox, an enduring feature of British locomotives. ‘Planet’ was followed by the ‘Patentee’ in 1833, which established the 2-2-2 as the archetypal British express engine and could be described as the first ‘modern’ locomotive.
     
    A detailed description of Stephenson’s ‘Patentee’ Locomotive Engine was published by John Weale in 1838 “by the liberality of Robert Stephenson, Esq., having been written under his direction and revision by Mr W.P. Marshall”
     

    Stephenson’s ‘Patentee’
     
    My model of the broad gauge ‘missing link’ is an example of this type of engine, which set the pattern for express engines until increasing size and weight dictated the use of more carrying wheels.
     
    Mike
     
  13. MikeOxon
    I shall round off my modelling of the early wagons, produced for the GWR during the formative years before 1840, by considering three types intended for specific duties, rather than the ‘general purpose’ wagons described in my previous two posts.
     
    Sheep Truck 1840
     
    A sheep truck is one of the types mentioned in Whishaw’s ‘The Railways of Great Britain and Ireland’, published 1842. He described these ‘trucks’ as having high sides, four wheels, and to weigh 8,237 lbs. Apart from that, there is very little documentary evidence to work from.
     
    There is a rather fanciful lithograph by L.Haghe, dated c.1840, which is supposed to show a GWR train at Kelmston near Bath. Some of the wagons are suspiciously similar to ones shown in an illustration of the Liverpool and Manchester Railway but they also show some ‘Broad Gauge’ features – notably the large wheels set outside the wagon bodies. The engine carries the name ‘Wharncliffe’ – not a known GWR engine name but that of the MP who steered the GWR Bill through Parliament.
     

     
     
    Eddy Brown deduced that the low weight rules out most of the known vehicle types of the time, except the Small Box Wagons. An additional factor supporting this idea is that these wagons, with their wheels outside the body, are the only ones with unobstructed floors, which would probably be essential for carrying small livestock, such as sheep. A stock list of 1842 includes a ‘wagon’ (no description) with a Tare Weight of 3T.-14cwt, which corresponds to 8,288 lb – close to Whishaw’s figure.
     
    Another drawing by Seymour Clark, dated Dec.1841, illustrates modifications that were carried out on three Luggage Wagons that were returned to Goods traffic after use on Passenger trains. These had underslung springs, which seem to have been applied to most wagons by this date.
     
    Based on these fragments of evidence, Broad Gauge Society (BGS) Data Sheet 413 shows the possible appearance of one of these ‘Sheep Trucks’, as mentioned by Whishaw. For my conjectural model, I have raised the sides of my model of a Small Box Wagon and exchanged the axleboxes and springs for the underslung type, which I had already created for other models. Raising the sides in ‘Fusion 360’ was simply a matter of selecting the top faces and using the ‘move’ tool. The software automatically extends the sides at the same angle as the existing sides.
     

    My 3D Model of an 1840 Broad Gauge Sheep Truck
     
    I felt very tempted to introduce slats in the sides but this would be pure conjecture on my part. I decided to complete my model as shown on BGS Data Sheet 113.
     
    Coke Wagon – 1840
     
    The Coke Wagon is the other variant mentioned in Whishaw, 1842. Following a detailed description of the 4- and 6-wheel wagons, described simply as ‘small’ and ‘large’, he mentions that there were also coke-wagons, mounted on six wheels, and each holding from 150 to 200 bags of coke.
     
    It is hardly surprising that these wagons were needed from the outset, as the steam locomotives of the time were fuelled by coke, to meet the Government requirement that ‘locomotives should consume their own smoke’. Whishaw reports that “The coke-ovens are situate at West Drayton, about half a mile to the east of the station ; and are very similar to those of the north of England and Scotland, being without a lofty chimney, which adds so greatly to the cost. They are conveniently placed on the level of the railway, which saves much labour in filling the wagons.”
     
    At the time, West Drayton was the central depot on the first stretch of line from Paddington to Maidenhead, opened to the public on 4th June, 1838. Wishaw notes that in thirteen weeks, including July, August, and September, 1839, the quantity of coke consumed amounted to 3,323,376 lbs (almost 1,500 tons) so, even at this very early stage, the coke traffic was considerable.
     
    BGS Data Sheet 406 states that 9 coke wagons were listed in a Stock Account dated 6th Oct.1840, and that these were based closely on the 6-wheel Utility Wagon, although with several minor modifications.
     
    The modifications included new wheel sets, with 11 split spokes, splayed outwards towards the hub. These represented my first new modelling task for this wagon. I created the flanged outer rim, and a hub to fit around a 2mm steel axle. I then drew a single spoke to the new design and completed the wheel by using the ‘pattern on path’ tool in ‘Fusion 360’. This automatically created a circular pattern of spokes around the central axis of the wheel. My models of both the original Losh wheel and the splayed-spoke wheels are shown below:
     

    My 4’ Dia Wheels modelled in ‘Fusion 360’
     
    In addition to the drawing included in BGS Data Sheet 406, the Coke Wagon is also shown in a more detailed drawing in Alan Prior’s book: ‘19th Century Railway Drawings’. I imported this drawing as a ‘canvas’ in ‘Fusion 360’ and compared it with my existing 6-wheel Wagons to determine the additional modifications required.
     
    The required changes included new 2-plank sides, without drop flaps. Because of the simplicity of the new sides, I decided that it was easier to create new sides than to remove the details of the doors from the existing model. In fact, when I created my previous variants, I sometimes felt it might have been easier to re-start some parts from scratch, rather modifying the old parts, which was often a very fiddly task.
     
    Other parts, including the end flaps and strouters could be re-used without modifications but the top rails along the side were now metal bars, for adding strength to the sides.
     

    Modified features in Coke Wagon
     
    There were some subtle changes to the chassis. The springs were now longer, still underslung, but mounted on bearings placed 3’ 6” apart under the frames (rather than 3’ 0” as previously).
     
    I created one new axle box and spring assembly and then copied this for all 6 wheels.
     
    The floor planking continued to run lengthwise and was laid over the headstocks and intermediate transverse bearers, which were higher than the tops of the Solebars, leaving a visible 3” gap underneath the floor, when viewed from the sides. This feature is shown clearly in Alan Prior’s book.. In addition, the Solebars were extended at both ends, so these could ultimately act as dumb buffers on tight curves.
     
    With these modifications applied, my 3D model, rendered in ‘Fusion 360’ is shown below:
     

    My 3D Model of 1840 Broad Gauge Coke Wagon
     
    Coal Wagon 1842
     
    These wagons are not mentioned in Whishaw’s account dated 1842 and probably came too late for inclusion there. The possibility of taking coal traffic in competition with the Kennet & Avon Canal presumably occurred to the Directors after the main line was completed between London and Bristol, with its proximity to the Somerset coalfield.
     
    According to Eddy Brown’s BGS Data Sheet 412, the evidence for existence of these wagons, specifically intended for carriage of domestic coal, comes from the 1842 Truck list, where one such vehicle has the description ‘Coal‘ and 9 others share similar Tare weights. There is also an 1840s drawing with the hand-written annotation ‘Coal Wg’
     
    The annotated drawing indicates a three-plank structure with sides supported by strouters and drop flaps at both sides and ends. Additional strengthening plates were shown over the axleguards, outwardly offset to disperse the greatest stress. As in the case of the coke wagons, described above, there was a clear space between the underside of the floor and the tops of the solebars.
     
    These coal wagons display most of the features included in the other ‘revised’ wagons, which were produced to meet the overall requirement for 250 wagons in time for the opening of the complete line between London and Bristol.
     
    My model is closely based on my Standard Box wagon. Because I had kept the various components as separate bodies within ‘Fusion 360’, it was easy to delete the original wheels and axle guards and replace them with the newer type, which I had already designed for the Coke Wagon, described above. I made a new top rail to encircle the whole body, above the sides and ends. In the prototype this rail was split into removable sections to facilitate loading and unloading.
     
    Following all these minor adjustments, my model of an 1842 coal wagon appeared as shown below:
     

    My 3D Model of 1842 Broad Gauge Coal Wagon
     
    For anyone interested in the onward development of Broad Gauge wagons, I have previously modelled another Coal Wagon, dating from the 1850s, described in an earlier post
     

    My 3D Model of 1853 Broad Gauge 12T Coal Wagon
    (iron frame, springs behind W-irons, brakes, & sprung buffers)
     
    Summary
     
    Over the course of three posts, I have described the creation of nine 3D models of Broad Gauge goods wagons dating from the earliest days of the GWR. Strictly, the Horse Box belongs to Passenger traffic since, at that time, horses were often transported along with the carriages owned by passengers. It seems, however, that some of these horse boxes were converted to Fish Trucks and appear as such in the July 1842 Goods Truck List. Conversely, some of the early goods wagons were used for the carriage of passengers, until the Government intervened and insisted on minimum standards for 3rd class passengers.
     
    The various wagon designs can be traced to three basic types – small box, large box, and 6-wheel box. My modelling has been an exercise in adapting models for different applications, which mirrors the procedures actually used for their prototypes. There are several cases where the amendments required for a new version were simply added to existing drawings.
     
    The complete ‘family’ of my 3D models, produced in this series, is shown below. Continuing my musical analogy with Trio Movements, I could describe these as ‘Variations on a Theme’:
     

     
     
    Mike
  14. MikeOxon
    I have already described my halting progress with 3D printing on my other Pre-Grouping blog, with the previous post having been made there on 3rd May.
     
    Since then, I decided to have a go at printing a Broad Gauge carriage of a type I have previously constructed using layered card sides, cut with my Silhouette Portrait machine.  This meant that I had already produced side elevation drawings of my chosen prototype in 4 mm scale.
     

     
    Thus, my latest ‘build’ was mainly an exercise to see what I could do with my 3D printer, and to combine various aspects of the carriage body into a single operation.  As I thought about it, I realised that all the internal partitions could be included in the print and then I added seats as well.
     
    A feature of early broad gauge carriages was that 1st-class compartments were sometimes divided into two sections, on either side of the centre-line of the carriage.  This resulted in two separate 4-seat compartments on either side of the carriage, with a connecting door between them, to allow the passengers on one side to reach a platform on the opposite side.  I decided to incorporate this feature into my design.
     
    The following illustraion, although not a Broad Gauge compartment, shows several interesting details, such as the cords to hold top hats, mounted under the low ceiling.
     

    As described in my earlier posts, I used Fusion 360 software to develop a 3D model of my chosen prototype on my computer.  My method was to extrude an open-top box from a profile of one end of the carriage, which included a ‘tumble home’ on each side and a curved top over which the roof could be mounted.
     
    The software allowed me to ‘paste’ a 2D drawing of the carriage side onto the computer model and I then used the ‘push-pull’ tool to inset the droplights and to open out the window openings.  I then drew the seat bases and partitions on the floor of the carriage and, again, used the ‘push-pull’ tool to raise these to the appropriate heights. 
     
    I still find that it needs a lot of trial and error to get all these details in their correct places and, when I make a mistake, I find it easier to delete and start again rather than attempting to correct my mistakes.  Perhaps, when I understand the software a little better, I shall find it easier to make such modifications.
     
    Once I had reached the point where it seemed worth trying to make a print, I used my Cura software to ‘slice’ the model into the format needed by my printer.  I could have used the Fusion software to do this but preferred Cura because I had already set this up with the characteristics of my Geeetech E180 printer.
     
    After slicing, the display on my Cura software indicated that it would take about 7 hours to print, which struck me as rather long but I didn’t investigate further.  In fact, it proved to be a fairly accurate estimate.
     

     
    Once it started printing, I realised the first of my mistakes!  After a previous test, when the carriage sides had turned out too thin, I had set the ‘infill’ to 100% which meant that the seats I had provided in the compartments were printed as solid blocks, which was very time-consuming!  At least it meant that the finished body had a reasonable weight (c.40 g) and was very rigid.  In spite of my profligacy in the use of plastic filament, the cost of materials was still only about 60 p!
     
    My second mistake was that, somehow, I had made some of the transverse partitions much too thin, so that they came out rather skeletal in form.  This can easily be corrected by adding some small rectangles of plastic card, although it has defeated my object of an ‘all-in-one’ construction.
     
    Thirdly, I had made the moulding lines too shallow so that they hardly appear at all on the model.  I must practice making such features, to find suitable dimensions for them to appear in 4 mm scale.
     
    In addition, the fact that I have had several reliability problems in the past meant that I was reluctant to leave the printer unattended for too long at a stretch.  If I can gain more confidence, then it would be preferable to do the printing overnight.  The printing would also have been a lot quicker if I had not included the unnecessary solid infill.  If I had set up for a 25% infill, the Cura software estimated a time to completion of only 4 hours, for the same model.
     
    On the positive side, there is no limit to the thickness of the side panels of the carriage, so there is no need to build up a side from several laminations, as is the case when using the Silhouette cutter.  Also, in spite of my concern, the printing proceeded without a hitch.  After having had some of my early models detach themselves from the base during printing, I was pleased to find that this model was quite firmly attached to the blue masking tape that I had used.
     

     
    In fact, for a model like this, which is mainly flat surfaces, it would almost certainly have been easier (and a lot quicker) to fabricate the carriage from Silhouette cut panels.  The trouble with my type of 3D printer is that the process takes such a long time that it becomes off-putting to make trial prints.  I had put off starting this model for some time for this very reason.
     
    I am expecting that the 3D printer will come into its own, when I make the chassis for this model.  I shall be able to use a suitable thickness of material, to make strong side frames, and will include spring and axle-box details as part of the process.
     
    That will be my next project ...
     
  15. MikeOxon
    In my previous post, I described making a 3D print of a Broad Gauge 1st / 2nd composite carriage, based on a prototype dating from 1854. With a bit of ‘Photoshop’ colouring, the 3D model of the body looks like this:
     

    3D-printed Broad Gauge Carriage Body
     
    After printing the body, I have now turned my attention to the under-frame and running gear.
     
    I have mentioned before the many useful ‘out of copyright’ books that I have found on the web, mostly in the ‘Internet Archive’.  My latest ‘find’ is a book by Daniel Kinnear Clark called ‘Railway Machinery’, published in 1855, which has proved something of a ‘gold-mine’.
     
    Amongst all the information about locomotives, track, etc., there are details of components such as wheels, axle-boxes, and springs, together with excellent drawings of many early carriages, including some early GWR Broad Gauge designs.
     
    Finding the 1st volume (text) on-line was straightforward but Vol.2, which contains the plates, proved more difficult, since many scans fail to copy the large ‘fold-out’ drawings. Fortunately, I eventually found a free download from Google Books at https://books.google.co.uk/books?id=QQ0cqi6y9vYC
     
    For some reason, I could not download this book from my usual Firefox browser but Internet Explorer worked: Just click on the wheel icon, at top RHS of the page, and select ‘Download PDF’ from the drop-down menu.
     
    These plates show details of the Normanville axle boxes, used on many early GWR carriages, and also the various wheel patterns, used at different periods, as shown below:
     

    Wheels and Axle-Boxes – from Daniel Kinnear Clark ‘Railway Machinery’ 1855
     
    I also found detailed drawings of a GWR Broad Gauge 1st class carriage, which includes details of the longitudinally-divided central compartments, the underframe, and the running gear.
     

    GWR 1st-class Carriage – from Daniel Kinnear Clark’s ‘Railway Machinery’ 1855
     
    By combining information from these drawings with that contained in the BGS Data Sheets, available to members of the Broad Gauge Society, I was able to prepare scale drawings in sufficient detail to design a 4mm-scale model.
     
    As usual, I found that the research took rather longer than actual model building but it is good to retrieve so many otherwise ‘lost’ pieces of information.
     
    As regular readers will know, I do not go for a high degree of mechanical precision in my modelling but like to create a general impression of the prototype, with as many correct dimensions as I can achieve, with my limited equipment.
     
     
    2D Sketch
     
    In creating the chassis, my first step was to prepare 2-dimensional drawings, using my favoured ‘Autosketch’ software. My end result is shown below:
     

    Sketch of Broad Gauge 6-Wheel Chassis
     
     
    3D Design
     
    Now, I had to decide how to turn this design into a 3D-printed model. Since it was over a month since I last used my ‘Fusion 360’ software, I had forgotten a great deal about how to begin but, fortunately, I have used my other blog to keep notes on my methods, as I went along. These proved invaluable in jogging my memory over many important ‘lessons learned’.
     
    It’s hard to know where to begin when modelling the complex assembly of parts that make up the running gear of a railway carriage. Should I model the individual components separately and then glue them together, as when using traditional design method?  As an experiment, I decided to try exactly the same technique as I used for the body, starting from the ‘floor’, immediately below the main body of the carriage and then using the extrusion (‘push-pull’) tools in ‘Fusion 360’, to create the sole-bars and head-stocks as an inverted open-top box. I then took my 2D drawing of the sides, including springs and axle-boxes, and ‘pasted’ the (DXF) drawing over the sole-bars, exactly as I described, in the notes referred to above, for placing the window-openings on a carriage body.
     
    It would have been extremely tedious to design all the details individually for each wheel but, fortunately, I am becoming more adept at using the various ‘move’ and ‘copy’ tools within the ‘Fusion 360’ software. I must admit that I’m not yet completely au fait with the precise meanings of terms like ‘bodies’ and ‘components’ but, with a little trial and error, I managed to select groups of items, such as spring leaves, and to link them together into a single entity, which I could then copy and move to locations aligned with other wheels.
     
    The copying process is a little cryptic, since it depends on a small check box at the end of a list of options for the ‘move’ command.
     
    Eventually, I was able to complete a reasonable representation of the sole-bar and its various fittings on one side of the chassis. Then, I thought that I should be able to mirror-image the work I had done, to create the opposite sole-bar with little extra effort. An initial ‘Google search’ for how to do this was somewhat dispiriting , until I realised that I was reading some old material, but a later ‘upgrade’ to ‘Fusion 360’ has made the task relatively simple.
     
    I first ‘cut’ my chassis into two halves, along its length, and deleted the half on which I had not added the details. Whereas the ‘move’ and ‘copy’ commands appear in the ‘Modify’ menu, the ‘mirror’ command took some finding, since it lies in the ‘Create’ menu. Once this was sorted, it was simply a question of selecting a plane to act as a mirror and the other half of the chassis ‘magically’ appeared on the base plane, a little distance away from the original. I then used ‘move’ to bring them together, followed by ‘Assemble’ to join up the halves into a single entity again.
     

    Stages in creating 3D Model
     
    Since I usually work by ‘following my nose’ (i.e. ‘empirically’), I only realised at this stage that it would be a good idea to provide holes in the axle-boxes, to accept pin-point wheel bearing cups. All that was needed was to draw a circle, centred within a face of the axle box, and use the ‘push-pull’ tool to take the opening across the body to the outer face of the opposite axle-box. One of the advantages of my ‘all-in-one’ approach is that the two sides are aligned automatically. I also opened slots in the floor to allow the wheels to protrude into wheel-boxes within the compartments, as on the prototype.
     
    Preparing the Printer
     
    A cause for concern was that the axle-boxes and springs overhang the area defined by the main frame members. This is a problem when 3D printing, because the final model is built up in layers and the printer head cannot lay down filament over empty space! For my experimental prototype, I decided to let the Cura ‘slicing’ software deal with the problem in its own way, by selecting to allow it to add ‘support structures’, where it considered them to be necessary.
     

    ‘Cura’ Layer View (152 layers) after ‘Slicing’
     
    The good news is that my first trial print went smoothly and quickly – well under an hour to complete. I am now gaining much more confidence in the printing process and was content to leave the machine to its own devices ‘for the duration’.
     
    In fact, despite some of my ascerbic comments over teething troubles with my Geeetech E180 printer, it is now proving extremely simple to use. I simply copy the ‘gcode’ file produced by the ‘Cura’ software onto an SD-card and place this into the slot in the back of the printer. Switch ‘on’ and select the required model on the touch screen of the printer, press ‘Print’ on the touch screen, then sit back and watch or get on with something else. Since the printer works from an SD card, it does not tie-up my computer when printing so I can get on with other modelling tasks.
     
    The fans start up and the printer pauses for a while, until the head reaches printing temperature (200°C) then immediately starts printing. I now set the ‘Cura’ to add a ‘brim’ around the model, which has two advantages: It (i) fixes the model securely to the (unheated) print bed, and (ii) ensures that any initial ‘blob’ of filament, as the printing starts, goes onto the brim rather than the model.
     
    Looking back, it seems strange that I initially experienced poor adhesion of the model to the print bed as I now have the opposite problem and find it difficult to remove the model without a lot of easing with a knife blade.
     
    Design Modifications
     
    My first prototype took under 1 hour to print but was too fragile and two of the axle-boxes broke off, while trying to remove the chassis from the printer bed. The springs had also become muddled with the support structures and were, again, too lightly constructed for a 4mm scale model. The lesson was that I needed to ‘beef up’ the thickness of some of my structures, in order to use plastic for under-frame construction.
     
    Now that I am more familiar with using the ‘Fusion 360’ software, I found it was quite easy to increase the thickness of various components, by selecting the faces I wished to move and then using the ‘push-pull’ command to make the necessary adjustments. The ‘thicker’ versions can be seen in the last frame of my illustrations of the process, above.
     
    Because there are a lot of small details in the model and the overall print time was relatively short, I decided to select the ‘extra-fine’ mode when printing. This lengthened the print time to about 2h 20m but did result in a finer surface finish.
     
    The Printed Model
     
    I’m pleased to write that the finished model exceeded my expectations. I had bought my printer as something of a ‘toy’ which I could use to explore a new technique and, perhaps, make some small component for my railway. I had never envisaged building complete carriages and am pleasantly surprised by how it has turned out.
     
    The underside view of the chassis, as removed from the printer bed is shown below. There were a few fine ‘fingers’ of filament sprouting from various corners and a finger-nail proved to be an excellent tool for removing these. Otherwise, the print had worked well, including the over-hanging springs, which I had thought might cause problems. The ‘extra-fine’ mode showed almost no layering effect at all on the vertical faces of the sole-bars.
     

    3-D Printed Under-Frame
     
    Wheels from the Broad Gauge Society fitted neatly between the axle-boxes and I soon had a ‘rolling’ chassis, as shown below:
     

    3D-printed ‘Rolling’ Chassis
     
    Finally, I brought together the chassis with the 3D-printed carriage body, to complete the overall model of an 1854 Composite carriage, with its internal partitions dividing the 1st class compartments into side-by-side pairs.
     

    3D-printed Model of Broad Gauge 1854 Composite Carriage
     
    With a coat of brown paint, it should fit well into my planned Mail Train. I should be able to use a very similar chassis for my planned 2nd class carriage, although this will also require brake gear.
  16. MikeOxon
    After printing my 1854 Composite body and its chassis, described in my previous posts, I turned my attention to making the very similar 2nd class carriage, built to an 1857 design.  
     
    Model conversion to 2nd class carriage
     
    The prototype had the same overall dimensions as the Composite, so I decided to see if I could easily ‘convert’ my computer model into this different type.  In essence, all that needed to be changed were the window locations and the compartment partitions.
     

    2nd class BG Carriage from 1857
     
    To my relief (and some surprise), this proved remarkably easy to achieve, when using Fusion 360.  This software keeps a record of each stage in the development of a model, so I could go back into my design, to the point before I added windows and partitions to my original carriage body. From that point, I could bring up my 2D drawing of the 2nd class carriage side and ‘paste’ it onto the side of the 3D drawing. 
     
    Next, I could simply use the ‘push-pull’ command to open up the window openings on both sides of the carriage.  I followed up by repeating the ‘push-pull’ operation on the window frames but only inset these by 0.5mm from the outer faces of each side of the carriage.  
     
    To make the partitions, I drew rectangles on the carriage floor, spanning the interior of the carriage and of 1mm width.  I placed these rectangles at each partition location and then used the ‘push-pull’ tool to raise them to the height of the carriage sides.  A simple operation, as all the partitions can be selected and extruded as a group.
     
    I saved the revised model and exported it as an STL file, for use by my 'Cura' slicer software to convert it into GCODE for my 3D printer.  The actual build process was then simply to copy the GCODE onto an SD card for the printer and press the ‘print’ button.
     

    BG 2nd class Carriage Model
     
    Following my experience with the solid seats in my Composite carriage, which took a very long time to print, I reduced the ‘infill’ setting to 20%, which caused the 'Cura' software to build up the seats with an open grid structure, as shown below:
     

    Carriage Seats with 20% Infill
     
    Printing problems
     
    Fortunately, I stayed with the printer, to watch the operation, and soon noticed that the model was lifting from the printer bed at one end.  This was a surprise, after having completed several successful prints, when the adhesion to the bed was, if anything, too firm!  
     
    I had, however, noticed that the first layer of the ‘Brim’ around my recent models seemed to print more firmly at one side than the other and had made some very small alterations to the bed-levelling screws, to see if that would even things up.  It seemed to have done so but, at the same time, my adjustment had decreased adhesion at the opposite side of the bed.  This brought home the lesson that bed-levelling is critical to obtaining uniform adhesion over the whole area of the model.  I suspect this factor is made more critical by the fact that my E180 printer uses an un-heated bed.
     
    This problem led me to undertake a very careful re-adjustment of all the levelling screws.  The first stage is to select the centre adjustment, which is done electronically from the touch-panel.  The bed height can be moved in 0.05mm steps until the print head just ‘grabs’ a sheet of file paper, slid across the bed.  
     

    E180 Touch Screen Levelling Controls
     
    After that, the print head is moved to the four corner locations, in turn, and the levelling screws adjusted until the sheet of paper is grabbed to the same extent as at the centre.  To do this accurately needs several iterations because, obviously, raising the bed at one side tends to tilt it, so affecting other points.  After a couple of ‘laps’ of all the screws, the paper ‘grab’ felt the same at every point, including the centre.
     
    I was pleased to find that this cured the adhesion problem on subsequent prints.  I shall now make a point of checking the level adjustments before each print-job, since it may well vary when a new layer of masking tape is applied to the bed.  Another ‘lesson learned’.
     
    Carriage Build
     
    Since I noticed the lack of adhesion very early in the printing process, I used adhesive tape to hold down the loose end and continued printing.  I was surprised to observe that, although the first few layers had been skewed, the printer was able to recover and laid down even layers for the rest of the model.   This allowed me to check that all the ‘new’ features of this carriage printed successfully – the window apertures all opened-out correctly and the partitions were of adequate strength.  The floor of the model, however was distorted at the loose end.


    First (distorted) Print of 2nd class Carriage
     
    I could still use this initial model, with some filler to close the gap between the carriage body and the chassis at one end.  The good thing, however, is that a re-print is very easy since, although it does take several hours to complete, the construction costs are extremely low and the ability to print, without tying up my computer, means that there is little penalty, in terms of taking up my time!
     
    Completing my Mail Train
     
    It is now over three years since I conceived the idea of modelling the train that was involved in the Bullo Pill accident of 1868.  The accident report contains a detailed description of the make-up of the Mail Train, so I could model each vehicle to re-create an authentic train of the period.  I described my original concept in a blog post from 2016 .
     
    To re-cap, my Mail Train consists of the Waverley-class 4-4-0 locomotive ‘Rob Roy’ with three carriages and a luggage van at the rear.
     
    My model of ‘Rob Roy’  is still not complete but, with the aid of my 3D printer, I am now able to make some of the necessary fittings, included the unusual inverted springs that link the leading wheels.  In fact, I have already printed a ‘fret’ of carriage springs for use under the Luggage Van at the rear of the train, as shown below.  
      The first two carriages are the 2nd class carriage, described above, and the 1st/2nd Composite described in a previous post.  After printing these, I have sprayed both these bodies with red-oxide primer and have painted the chassis black.  
        The third vehicle is a Mail Coach, which I built from a Broad Gauge Society (BGS) kit, as described in a series of earlier blog posts .
      The Luggage Van is another BGS kit, this time with a laser-cut resin body, described in another earlier post.  
     

    Springs for Luggage Van
     
    Although there is still a lot of work to do on all the individual models, I could not resist setting out the complete train, in its current state, on a shelf and photographing the result:  
     

    Model Mail Train (unfinished)
     
    I do find that taking these photographs provides me with the inspiration to keep going and I feel that, with the aid of my 3D printer, I now have the means to complete outstanding tasks.  I shall next turn my attention back to ‘Rob Roy’.
     
    Mike
  17. MikeOxon
    This post is a miscellany of ‘lessons learned’ on my journey to incorporate 3D printing into my railway modelling work-flow
     
    Removing window in-fill
     
    All the carriages I’ve printed so far have an amount of supportive in-fill within the various window apertures. This has proved surprisingly difficult to remove since, although the infill is very thin, it clings very tenaciously to the edges of the window opening. I tried several tools, including small cutting tweezers, wax-carving chisels, and needle files but, eventually, I had the greatest success with a blade from the Modelcraft Precision Saw Set (0.24mm)
     

    Clearing in-fill from window openings
     
    The Modelcraft set includes 6 very fine saw blades (0.24mm thickness). intended for intricate sawing and cutting in plastics, wood, and photo etched parts. These blades fit onto scalpel handles.
     
    Unlike scalpel blades which readily break, if used for sawing actions, these blades are flexible and can be used both to stab into the thin plastic film and then to work around all the edges of the window frame. In some cases, some of the infill was found to have folded back against the inside wall of the carriage and, in such cases, a small wax-carving chisel was a good removal tool
     
    Printer Bed Adjustment
     
    In my last post, I described problems that I had with adhesion of my models to the bed of my Geeetech E180 printer.  I am pleased to have discovered for myself how important the process of setting up the alignment of the bed is, to achieving successful results.  Now that I have attended to this detail, my prints have been very consistent and, while remaining firmly in position during printing, have been removable from the bed without ripping up the blue masking tape.
     
    The improvement in reliability has done a lot to raise my confidence in the 3D printing process as being one that can produce good results with very little user input being required, after the initial computer model has been drawn.
     
    Repeat Prints
     
    After an adhesion failure, which resulted in a distorted carriage body, as described in my previous post, I simply re-inserted the same gcode file into the carefully set-up printer and pressed the ‘print’ button. All went well and about 5 hours later, I had a non-distorted carriage, with no intervention being needed on my part.
     
    I was surprised to see that, when I placed the two carriage bodies side by side, many of the printing blemishes were in exactly the same places on both. I had thought that these were random errors due, perhaps, to backlash in the mechanisms or other mechanical tolerances but, instead, it looks as though they are systematic defects arising from the way the print head tries to follow the instructions provided by the ‘layer’ model from the slicer software.
     

    Comparison of two successive prints
     
    Curved Roofs
     
    I decided to do some more experiments, to see whether my 3D Printer could produce a reasonable curved roof for my carriages. My initial thought had been to use a rectangle of plasticard, moulded to shape by judicious application of a little heat, as described in a previous post , when I built other carriages.
     
    The possibility of using the 3D printer, however, was too strong for me to resist, so I had a go with the simplest structure I could devise. I sketched a pair of arcs, using the Fusion 360 software and then extruded the sketch by means of the ‘push-pull’ command, to form a 1mm thick single-curvature roof. I added some rectangles close to the edges of the under-side, to form a ‘base from which the roof could be ‘grown’. It was an experiment, since I was fully aware that the raised part along the centre of the roof would have no underlying material and would be dependent on support from the adjacent strips, as the printing progressed.
     

    Sketching the Roof Profile in Fusion 360 software
     
    In the event, I thought that the result was surprisingly good – while not perfectly smooth, the curved upper surface showed only very light grooving. On the other hand, because it started with all the edges lying on the printer bed, there were no alignment features to locate the roof into its correct position over the body.
     

    Printed Roof - Surface Finish
     
     
    Adding location lugs to a roof
     
    My next step was to add some vertical 'lugs' running downwards from near each end of the roof, placed so as to engage with the inside faces of the end walls of the carriage.
     
    This introduced the problem that the edges of the roof itself could no longer be in direct contact with the printer bed, so I selected the options in the Cura software to add support structures, where necessary. I used the default ‘zig-zag’ support style and allowed the print to take its course.
     

    Zig-zag Support Structure Underneath the Roof
     
     
    I was somewhat surprised to see how ‘dense’ the resulting support mesh appeared to be, at least at first glance. In fact, the ‘cellular’ structure only applied to the very first layer, in contact with the bed, and subsequent levels of the structure were a zig-zag pattern of very thin walls, rising throughout the structure. This support structure proved much easier to cut through with a knife-blade than I had expected, although it did leave lots of strips of thin material, on which I used a wax-carving chisel, to slice them away from the underside of the roof.
     

    Removing Support In-fill
     
     
     
    ‘Soldering’ with PLA filament
     
    In chiselling away these support structures, I inadvertently broke off one of the lugs that I had designed to hold the roof in position on the body. At this stage, I tried another technique that I had seen described on the web
     
    This is the somewhat surprising technique of ‘soldering’ the PLA plastic. By setting my soldering iron, fitted with a small conical tip, to a temperature of 200°C, it melts the PLA  in exactly the same way as does the print head itself.
     
    By running the hot tip of the iron along the damaged joint, the plastic readily melted and welded together the two sides of the joint, to form a strong bond. Larger repairs can be made by introducing additional PLA filament, in much the same manner as one would use a solder fillet!
     

    Using Soldering Iron for Seam Weld
     
    This made me realise that more complex structures could potentially be assembled from 3D printed parts by using a soldering-iron in much the same way as one would when assembling an etched-brass kit. I think this method of assembly could open up a whole new realm of possibilities.
     
    Finishing the Roof
     
    Although the surface finish of my 3D-printed roof was better than I had anticipated, it was far from perfect. To overcome the slight 'grooving' and achieve a smooth surface, I applied a film of self-adhesive vinyl to the 3D printed surface, which completely masked all the small ‘steps’ produced by the layered printing process. The final roof (sprayed with grey primer) is shown below, on my (unfinished) Composite carriage body and chassis.
     

    Vinyl-Covered Printed Roof
     
    The same methods could be used for more complex roof shapes and I plan to re-visit the clerestory roofs that I fabricated for some of my previous models. It should also be possible to add features, such as oil lamp housings, as part of the 3D print.
     
    Mike
  18. MikeOxon

    3D-Printed Cattle Wagon - 1

    By MikeOxon,


    General
    As I wrote in the previous post, I found plenty of inspiration from my research into Broad Gauge cattle wagons. It gave me the impetus to move straight on with the design of a 3D-printed model.
     
    Whereas I created my 3D printed carriages by extruding the carriage from one end, I felt that the sides of these wagons might be better printed while lying flat on the printer bed. This would mean assembling the wagon from separate parts for the sides and ends, mounted on a rectangular base, rather like assembling a plastic kit. The reasons for taking this approach are that there are several different layers, representing frames, planks and strapping, plus several large apertures, both horizontal and vertical, which would need a lot of additional support if printed vertically.
     
    The first step in building a model is to prepare a suitable drawing. In this case, there wasn’t a lot of written information or specifications but a line of wagons appears in the background of a locomotive photo. This photo shows a little more than half of one side of a cattle wagon, although many details are obscured by the foreground. There is more detail of the central section of another wagon, which shows details of hinges, door fastenings, and strapping. I have annotated two sections of the photos below to show various features:
     
     

    These sections were the sources for the ‘composite’ image that I created by photo-editing these fragments.
     
    I decided to accept the key dimensions of 16’ 6” length and 7’ height for the body, plus a 9’ 9” wheelbase, as described in the Broad Gauge Society magazine ‘Broadsheet’ No.52. Taking these proportions, I set about ‘matching’ the sketches of the closed wagon, shown in the same article, to the partial views in the photograph. For this, I imported the composite image into ‘Autosketch’ and traced over the main outlines to obtain a proportionate sketch.
     
     

    ‘Autosketch’ screen, showing lines traced over the photograph.
     
    I then scaled the ‘not to scale’ drawings in the ‘Broadsheet’ article, to see how well the locations of the various features were in agreement between the two drawings. Apart from the wider door posts in the photograph, the two drawings match up well, in terms of the main features, so I felt confident to go ahead with preparing a 3D-print from my own drawing.
     
     

    My sketch overlaid on the ‘Broadsheet’ sketch (re-scaled)
     
    For some reason, I have been having difficulty with transferring my recent DXF-format drawings into ‘Fusion 360’, whereas older drawings (of standard-gauge carriages) went well**. Fortunately, the current drawings were relatively simple and I was able to work through the various ‘open ends’, where lines should have met, and match the ‘nodes’ by hand.
     
    I then worked through the various panels, using the ‘push-pull’ tool to recess them behind the main frame components by suitable amounts. As always, I found it tricky to make the various precise ‘incantations’ required for ‘Fusion 360’ carry out my requirements in exactly the right order and format but, after several false attempts, I arranged everything to my satisfaction. I think part of the problem arises because the software works ‘on-line’, so there are often short delays between initiating an action and it being completed. It can be a little like trying to hold a trans-Atlantic phone conversation when there’s a delay on the line.
     
    I started on another learning curve when creating the sloping slats above the window opening. This involved using the ‘chamfer’ tool, for which an edge has to be selected and then two distances along the faces that meet at the edge are specified. Following my usual approach, I applied trial and error until I got the effect that I wanted.
     
    There are 8 slats in all and the first 7 went smoothly enough but no.8 simply refused to work properly! After a lot of head-scratching, I found it was another problem in the drawing, where two edges had failed to ‘fuse’ together correctly and, as a result, the chamfer kept being applied in the wrong place.
     
    Sadly, after all the attempts I had made to understand the problem, something went wrong with the locations of the bars across the window openings and some of them ended up protruding from the back surface of the model, which was supposed to lie flat on the printer bed. I have no idea how this happened but I had to undo several steps to unravel the mystery and then re-do my slats.
     
    I mention this to illustrate some of the mishaps that can so easily occur when creating 3D models. It is definitely not an activity for anyone lacking patience! When frustration sets in too badly, I find it best to stop and come back later, when the mind has cleared and it is easier to assess the causes of a problem. A good feature of ‘Fusion 360’ is that it maintains a ‘time line’ of actions across the bottom of the screen, which makes re-tracing one’s steps fairly easy.
     
     

    My 3D drawing displayed on ‘Fusion 360’ screen.
     
    At this stage, I decided to do a test print and was pleasantly surprised by the result. It’s a pity that some of those details that involve so much effort are almost invisible when produced in 4 mm scale but it’s nice to know they are there.  Encouraged by this success, I decided to add some more details, such as bolt heads on the door straps and lines between the planks (shown above). I was concerned not to over-do the plank edges and ended up with them being barely visible. Again, a reminder that details are easily ‘lost’ in the final print.
     
    The final result looks good, although I have ‘cheated’ a little with the photo to change the garish blue colour of the filament I use to a more ‘sympathetic’ brown. The detail, however, is exactly as it came straight out of the printer.
     

    My 3D-printed side (re-coloured)
     
    Next steps are to print the ends and then to decide how to assemble a complete model.
     
    Mike
     
    *  EDIT -  After another look at my images of the real wagon, I have realised that the support on each side of the doors appear to be angle irons, rather than the broad wooden door-posts I depicted in my model.  I shall make an appropriate modification to my 3D drawings for a re-print.
     
    ** EDIT - I've now realised that I had become lax in setting 'snaps' in Autosketch - hence the small gaps.
  19. MikeOxon

    3D-Printed Cattle Wagon - 2

    By MikeOxon,


    General
    Following my previous post, where I showed how I made a cattle truck side, I have followed a rather convoluted route to arrive at a model of the complete body.
     
    I could have printed a flat floor and some ends and then pieced all the parts together but I got caught up in the idea of trying to print the whole body in one go. I soon abandoned this idea, when I realised it was going to involve a lot of support structures for the various horizontal openings, but I did get as far as forming a body shell by the same method I have used previously for carriages.
     
    Then, I had the idea of making the floor and ends as one ‘component’ and the roof as another, onto which I could fasten my already-printed sides. The selection of the various parts proceeded as shown in the following screen shots from my ‘Fusion 360’ software:
     

     
    Step 1 shows how I extruded the body from a drawing of one end of the cattle wagon – the overall length is 66mm, corresponding to 16’ 6” in the prototype. In Step 2, I set a reference plane, offset by 25mm above the origin, and used the ‘split body’ tool to separate the roof. In Step 3, I drew a rectangle on the top of the main body and used ‘press-pull’ to open out the interior leaving just the floor and ends. Step 4 shows one of the body sides, which I described in the previous post.
     
    I exported each of these separate body parts (floor + ends, sides, and roof) to my ‘Cura’ slicing software and used this to create the gcode print files, used by my E180 printer.
     
    One advantage of making the components individually is that they print relatively quickly, since there is very little ‘depth’ in each component. Typical printing times were around 45 minutes for each component, so it was not too long to wait before I had all the parts for the body of my cattle wagon.
     
    The next consideration was what glue should I use to assemble the model? The answer, as I discovered in a previous post was ‘none’. I set my temperature-controlled soldering iron to 200°C and used the tip to ‘weld’ the sides to the ends of the body. This is a very easy process because the plastic of the body has low thermal conductivity, so there is no danger of melting more than I intended. Also, it’s easy to hold the pieces in register while applying the soldering-iron tip, with no danger of burnt fingers. The bond is formed almost instantly and seemed very robust after a few moments of cooling.
     

     
    First of all, I carefully aligned one of the side panels to one of the end walls, then used heat from the iron to weld the outer corner. Once this was secure, I ran the iron along the seam, to make a firm ‘welded’ joint. I fixed the other end of the side in the same manner and then continued by fixing the second side panel.
     
    Of course, I could not fix the roof in the same way, as I have no access to the interior of the wagon once the roof is in place.  I intend to use a hard-plastic adhesive but, as yet, the roof remains unfixed until I complete the painting.
     
    After completing the body, I turned my attention to the chassis. I used a similar method of construction to that used earlier for Broad Gauge carriages. I printed the floor ‘upside down, with the axle boxes and springs built up by printing upwards from the floor. The design as developed in ‘Fusion 360’ and then 3D-printed from ‘Cura’, is shown below:
     

     
    The next question was what livery to use. According to the Broad Gauge Society journal ‘Broadsheet no.6’ (1982), the earliest livery, as applied to an iron goods brake van in1852 was: "The whole of the van including the wheels, axles, axleboxes, side springs and every part … brown colour and figures as might be directed,". Similar specifications apply to other early wagons, so I assume from these specifications that ‘waggons’ and break vans were all-over brown in the 1850s.
     
    The following photo shows the model in its current state, although I have altered the colour in Photoshop as I have not done any painting yet. During the 19th century, it was standard practice to lime-wash the interiors of cattle wagons, which led to extensive white stains on the outside as well, so I shall include these when painting the model.
     

     
    My initial simple chassis design is insufficiently robust, so more work is needed.  I only realised at a late stage that the cattle wagon is narrower (at 8' 6" wide) than the carriages I have built before and this left insufficient room for strong axleboxes. I need to investigate alternatives, which may need white metal boxes to achieve adequate strength.  Once I have a suitable chassis design, I shall continue to the 'open-top' style of cattle wagon, to add some variety to my planned cattle train.
     
    Mike
     
  20. MikeOxon

    3D-Printed Cattle Wagon - 3

    By MikeOxon,


    General
    Building the Chassis
     
    This is an addendum to my previous post about building a Broad Gauge cattle wagon body. Although I built a chassis at that stage, I found the construction was too light and would not support wheel-sets adequately. I should have remembered that I had the same problem with the first design I did for a carriage chassis, so this post is an aide memoire to help me avoid the same mistakes again.
     
    My chassis is basically a rectangle to fit under the body, with axle-boxes and springs added in the appropriate places. Building the rectangular plate in ‘Fusion 360’ is straightforward but adding the axle-box details proved more tricky.
     
    My staring point was to make a 2D-drawing of one side of the chassis, showing the locations and sizes of the various components that make up the under-gear. For this, I used ‘Autosketch’ to produce the drawing shown below:
     

     
     
    Next, I produced the base rectangular plate in ‘Fusion 360’. I started by drawing a rectangle 66mm x 34mm and extruded this, using the push-pull tool, to make a plate 3mm thick. I drew additional rectangles on the surface of the plate and recessed these by 2mm (push-pull again) to form a basic chassis with sole bars around the edges and some internal support at the centre.
     
    Next, I imported the 'Autosketch' drawing (saved in DXF format) and extruded the various elements of the drawing to form the running-gear components along the side of the chassis. This was quite complex, since I first extruded inwards to make a firm attachment to the sole-bars and then outwards to form the outer faces of the axle-boxes and springs. These Steps are illustrated below:
     

     
                   Step 1: the 3D chassis;                                                                    Step 2: adding the side drawing
                   Step 3: extruding over solebar;                                                     Step 4: extruding outside faces
     
    Once I had completed the axle-boxes along one side, I realised that the various parts all appeared as separate ‘bodies’, so I used the ‘Combine’ command on the ‘Modify’ menu to make the whole assembly into a single ‘body’.  This is important because only a single ‘body’ can be exported to ‘Cura’ for 3D printing.
     
    The next stage proved tricky since I fell foul of one of Fusion 360’s quirks.
     
    My aim was to split the chassis lengthwise and then make a mirror image of the side with the axle-boxes and use it to complete the opposite side.  My first step was to create an offset plane along the mid-line of the chassis, using the 'offset plane' command in the ‘Construct’ menu. I could then use the ‘split body’ command in the ‘Modify’ menu to create two ‘bodies’, one for each side of the chassis.  When I tried to delete the unwanted side, however, I received error messages :
     

     
    If one is foolish enough to continue, then large parts of the model disappear! Clearly, this is not the right approach.
     
    Eventually, I succeeded after several attempts, during which I learned to understand the difference between ‘Delete’ and ‘Remove’, when applied to ‘bodies’. Everything worked fine, providing I used ‘Remove’ from the drop-down menu that appears when right-clicking on the relevant ‘body’. Another step on the learning curve   I have summarised the steps needed to complete the model in the following diagram:
     

     
     
    In step 5, I set up an offset plane half-way across the chassis, then selected ‘split body’, to cut the chassis into two halves. In Step 6, I selected ‘Remove’ from the drop-down menu associated with this body.
     
    In Step 7, I used the ‘Move/Copy’ command to copy, rotate and move a copy of the original body (complete with axle-boxes) to lie alongside the original. It is important to check the rather insignificant box near the bottom of the menu to ensure that the original is copied and not simply moved!
     
    After aligning the two parts, I used the ‘Combine’ command to join all the parts into a single ‘body’, which, in Step 8, I could export to my 'Cura' 3-D printing software.
     
    One additional action was to mark and extrude rectangles behind each axle-box, to allow the wheels to protrude through the chassis floor. After all this, I could send the model to my 3D-printer to produce a chassis for my planned fleet of 9’ 9” wheelbase cattle wagons. Phew!!!
     

     
     
    Learning curves are strange things.  I now do with aplomb, things which seemed almost impossible a few months ago but I can still come to a grinding halt when faced with how to remove an unwanted body.
     
    Similarly, the adhesion problems I had initially, when printing, seem to have disappeared. In fact, the adhesion has recently seemed too strong and I also noted that the filament was tending to form blobs at times. Reducing the print temperature from 200°C to 190°C appears to have solved both these difficulties.
     
    My second print head has, however, just failed. Since this is a special clip-in component, no longer readily available in UK, this may bring my time with the Geeetech E180 to a sudden halt, as I now have only one spare remaining. They do not seem to last very long!
     
    I can now show my first cattle wagon body standing on its wheels – Broad Gauge, of course
     

     
    Still a lot of work on fittings and painting.
     
    Mike
     
    EDIT:  I made some minor adjustments to the 'push-pull' features on the axle-boxes / springs, which have made a significant improvement to their appearance - photos updated.
     
     
  21. MikeOxon

    3D-printed Double Fairlie

    By MikeOxon,


    general
    Background
     
    Several years ago – 2006 in fact – I was driving away from a visit to Blaenau Ffestiniog slate quarries and noticed that the last train of the day was due to arrive at the railway station.
     
    It turned out to be quite a long wait, as the train on the Festiniog Railway was in trouble and eventually arrived with a broken flexible steam pipe to one of the power bogies. With a sense of ‘make do and mend’, the trailing end of the pipe was lashed up and the train then made a very late start for Porthmadog, relying on just one power bogie for the downhill trip
     

    Broken Steam Pipe of ‘David Lloyd George’
     
    At that time, my small model railway was in abeyance, although I did think briefly about the Langley Models kit, which seemed rather basic and also required the purchase of an American diesel to provide the chassis.
     
    Now, there is the Bachmann model, which looks very nice but, at £200, this is too expensive just to satisfy a vague whim. It’s too long anyway for my rather tortuous narrow gauge track around the North Leigh quarries.
     
    I did feel an ‘itch’, however, to try one as a 3D modelling task. I felt it provided an interesting challenge to lay out the components in such a way that they could be printed on my basic FDP printer.
     
    Steps to Creating My Model
     
    I found a drawing by Ian Beattie of a ‘typical’ Festiniog Double Fairlie in ‘Railway Modeller‘ November 1992, which I have used as a basis for my model. I also found a very helpful photo of an unclad ‘Merddin Emrys’ at Boston Lodge on the Festiniog ‘Facebook’ pages. This showed me several normally hidden details of the boiler and its supporting structures.
     
    The Footplate
     
    Following my usual method, I imported the Ian Beattie drawing, as a ‘canvas’, into Fusion 360. I started by extruding the footplate from the plan view in this drawing collection, as shown below. I designed this so that the top surface was completely flat and could be laid on the bed of my FDP printer
     

    Extruding the Footplate in Fusion 360
     
    Since I do not have a practical application for this type of engine, I am treating it simply as a design exercise.
     
    The Cab and Firebox
     
    The next challenge was the central cab. Since I had included the parts of the sides below the footplate and the firebox plinth in my initial footplate component, I had to create a part that would sit flat on the firebox plinth. I first drew the front and back ends of the cab by tracing over the drawing. The sides were a little more complex, because of the ‘joggle’ in the width, at mid-height.
     
    I created a 1mm ‘offset’ drawing inside the edges of one of the end walls of the cab and then extruded this profile along the length of the cab to create both sides and the roof. I then drew the outline of the side opening on one side of the cab and used the ‘push-pull commend to cut out these openings through the entre width of the cab. These stages of my construction are illustrated in the following drawing:
     

    Steps in designing the Cab for my Model
     
    After the extrusion described in Step 1, my next Step 2 was to add the other end wall to the cab and then complete the assembly by adding a floor, which would sit on the firebox plinth, when printed.
     
    Step 3 shows the twin firebox, which was a separate extrusion and, as in the case of the cab, I drew the detail of the fire doors on one side of the box before using the push-pull tool to emboss the details of the two doors. I also added the shaft for the handbrake. Similarly, I added some details of the reversing lever on the opposite (Driver’s) side of the firebox.
     
    Step 4 shows the complete cab with the firebox inside, aligned over the footplate, which I had extruded first. Note that the large holes through the length of the firebox and cab ends are to allow a brass tube to be passed along the whole length of the printed model, to act as a ‘spine’, both to align the two boilers and to hold everything together.
     
    The Side Tanks
     
    The next challenge was presented by the four side tanks. Those on the Fireman’s side contain coal bunkers while, on the Driver’s side, there are tool boxes on top. These tanks form mirror-image pairs at each end of the engine.
     
    To create the tanks, I started by extruding from a rectangular base to the height shown on the drawing,. On the prototype, the tanks have extensions on their inner sides to fit around the boiler. I created these by drawing the end profile and extruding this along the length of the tank. I added the tank fillers by extruding upwards from the top surfaces of the tanks, after drawing their profiles.
     
    The coal bunkers were extruded in two parts: a rectangular base and the (initially) vertical plate behind the bunker. I then used the move tool to tilt the plate to the angle shown on the prototype drawing. After joining the two parts together I moved them into position on top of the relevant tanks (on the Fireman’s side) as shown below:
     

    Coal Bunker on Fireman’s Side
     
    Adding some Coal
     
    As an interesting exercise, I thought that I would try adding a simulated coal load by means of 3D printing. In a previous post I described how I used an extension to Fusion 360 to create a surface texture. This comprised a ‘plug-in’ for 'Fusion 360' called ‘Image2Surface’, which adds the capability for 'Fusion 360' to create a textured surface from a 2D image. Downloading the appropriate software and then getting it to work was not straightforward but, fortunately, I found a 'YouTube' video, which explains the procedures very well.
     
    In my previous post, I created a textured surface based on a photograph of gravel ballast. It occurred to me that the appearance was quite similar to that of small coals in a bunker, so I made a copy of my previously created texture and used the cutting tools in ‘Fusion 360’ to make a rectangular section to fit in the top of my coal bunker. The result is shown below:
     

    ‘Coal’ texture panel above my rectangular Coal Bunker.
     
    With appropriate colouring, I feel that the gravel texture provides a reasonable representation of the top of a filled bunker! There is an important caveat when creating surfaces by this method – they can involve a very large number of facets and vertices, which results in very large file sizes. Even though my model bunker top only measures 4 mm X 17 mm, the .STL file that describes it occupies a staggering 258 MB. Of course, I could easily reduce that size by reducing the level of detail but the act of ‘slicing’ the model for printing reduced the size anyway, to a manageable level.
     
    This is a technique to bear in mind for small applications but not really suitable for creating large areas of ‘facings’ on buildings and other scenery.
     
    The Boilers and Smokeboxes
     
    The two boilers are identical and are simple cylinders, formed in exactly the same way as I have described for many earlier engine models. Similarly, the boiler fittings and smokebox all followed my usual methods. Once I had brought all these parts together within the ‘Fusion 360’ software, my 3D model looked like this:
     

    My 3D Model of a ‘typical’ Double Fairlie
     
     
    Printing my Model
     
    As usual, I printed my model as a set of components, arranged so that each could be built up from a flat surface. With experience I have found that my FDP printer is far more tolerant of overhangs than I had initially thought. I now take more ‘liberties’ in the design and find that quite large openings, such as where the boilers fit into the cab ends, can be printed without any additional supports or ‘helpers’
     
    I have previously printed smokeboxes as open tubes and added the curved front door separately. This time, I tried printing the smokebox as a single item and was surprised to find that my printer bridged the hollow centre behind the curved front without difficulty. I suspect that the ability to bridge gaps during printing depends strongly on the temperature of the filament when it is extruded.
     
    The largest single part was the footplate and I printed this ‘upside down’ on the printer bed, taking advantage of the extensive flat surfaces. Note the opening in the cab side, which is ‘bridged’ without any additional support.
     
     

    Footplate Model on the Printer bed
     
    Next, I printed the cab, which comprises the end and upper side walls, up to the level of the roof. Note that the lower side walls and a plinth for the firebox were included as parts of the footplate component.
     

    3D-printed Cab, mounted on Footplate
     
    The holes in the cab end walls are to accept a brass tube which runs the length of the model and holds the boilers and smokeboxes in alignment. This tube also adds weight to the structure.
     
    I printed several of the smaller parts – sandboxes, domes, and chimneys – together as a group. They all printed surprisingly cleanly and despite the small contact areas remained firmly attached to the printer bed. This set of parts took just 12 minutes to print!
     
     

    3D-printed Small Components
     
    For this model, I set the layer height when printing at the ‘normal’ setting (0.15 mm) rather than the ‘fine’ setting (0.10 mm) , which I use when there are rows of rivet detail or other detailed structures. This does mean that some ‘banding’ is visible in the photographs but is not noticeable at normal viewing distance on a 4 mm scale model.
     
    My complete set of parts after printing is shown below:
     

    3D-printed Components of my Fairlie model
     
    The first step in assembling the parts was to place the twin-firebox unit within the cab. I then inserted the central rod and slid the two boilers and smokeboxes over this, to check the overall alignment – which was good. I used superglue to hold this partial assembly together. I have read in some places that superglue does not work well on PLA plastic but that is not my experience, provided it is given time to polymerise. In fact, I have sometimes found it difficult to separate parts that I have inadvertently not aligned properly!
     
    Adding the tanks came next. It’s important to get each tank in its correct position since they are all different! After a little trial and error, I found that the best method was to glue each tank to the appropriate end of the cab, ensuring that they were aligned correctly with the two boilers and that the tanks and cab all sat flat on a plane surface.
     

     
    3D-printed Model with tanks glued to cab
     
    Once the bonds had hardened, I added the various small details – sandboxes, domes, and chimneys - by means of tiny drops of glue under each, then holding them in position for a few moments until the joint was firm.
     
    Finally, I could glue all this ‘upper’ structure to the footplate, which was rather flexible on its own but gained rigidity once glued to the lower surfaces of the tanks. The complete assembly then looked as below:
     


    My 3D-printed double-Fairlie model
     
    I have thoroughly enjoyed designing and constructing this model. Of course, the issue of the two power bogies remains!
     
    I intend to apply lining and lettering by means of printed vinyl overlays as described in my earlier series of posts about ‘lining and lettering’.
     
    Mike
     
     
  22. MikeOxon

    3D-Printed Horses

    By MikeOxon,


    general
    After reading some recent posts about horse drawn wagons and the like, I started to wonder if it would be possible to 3D-print my own horses.
     
    A look at the 'Cults' website yielded a 3D-printable horse  by David Mussaffi, described as ‘FDM printer ready’, so I thought that this would be a good place to start.  I looked at the file after loading it into my ‘Cura’ slicing software and found that the model was cleverly split into three parts, such that there were flat surfaces to lie on the printer bed, with no overhangs that would require support structures.  The original design was rather large for 4 mm scale, so I adjusted the ‘scale’ setting in ‘Cura’ until I felt it was a reasonable size for use on my railway. The following illustration shows the three parts, as they appeared on my printer bed,
     

    Three components of downloaded horse by David Mussaffi – as printed
     
    Once separated and carefully trimmed along the edges, these three parts fitted together very well, to make a complete model – in fact, I was pleasantly surprised by the result and decided that a few of these 3D-prints would be useful additions to my railway, for pairing with various vehicles. Differences in texture are visible on this unpainted model but I felt that, with a little more fettling and painting, a very satisfactory model could be produced.
     

    3D-printed horse after assembly of 3 components
     
    I also realised that by adjusting the overall scale and/or individual parameters such as girth, it would be possible to produce a range of different types of horse from the same basic design.
     

    3D printed horse variations
     
    Horse Shunting
     
    A few years ago, when I set up a scene on my layout involving horse shunting, I found myself musing on whether there might be any way of simulating a walking motion.  I wonder if any readers remember the little ‘ramp walker’ toy that once came in cereal packets? A string could be attached to a model horse and hung over the edge of a table, attached to a small weight. This would cause the horse to ‘walk’ to the edge and then stop.

    ‘Cereal Packet’ Horse Walker
     
    When I first thought about it, a few years ago, I could see no way in which I replicate a model of this type at an appropriate size. Now, however, having gained some experience in using a 3D-printer and having created a 3D-printed horse, the thought entered my mind again and I thought it was worth ‘giving it a go’.
     
    Well, I’ve had a go but still haven’t succeeded in making it walk! I suspect that there is a problem of scale. If I halve the linear dimensions, then the surface areas decrease by a factor of four and the weight by a factor of eight. I suspect such changes upset the relationships between movement, weight, and friction that make the model work.
     
    I have documented the steps I’ve taken so far in the hope that someone will be able to suggest which parameters to change, to make it work. After around 3 months of fiddling with it, I’ve run out of ideas!
     
    Downloaded 'Walker'
     
    The trouble from the outset was that I had only a vague idea of how the walking action worked, so I looked on the web and found another model on the 'Cults' website, described as a '4 legs walker'. This model consists of a simple ‘body’ and a set of pivoted legs, which enabled me to examine the principles behind the ‘walking’ motion. I knew, however, that I would have to produce a much more realistic looking ‘body’!
     

    Downloadable 4legs-Walker, showing shaped feet
     
    Now the fun began, as I contemplated how to adapt the ‘realistic’ 3D-printed horse to the ‘walking’ principle! I was encouraged by the fact that the horse model I had downloaded was already divided into separate parts that I might be able to adapt to a suitable new configuration.  So, I started on a new ‘learning curve’! What follows has taken a few months of ‘trial and error’ (mostly the latter) but the main steps are summarised below:
     
    Meshmixer
     
    The first hurdle was to get the downloaded horse model into my 3D-modelling software ’Fusion 360’.  It is possible to import a mesh (STL) file but, when I tried to convert this model into an editable ‘body’, I immediately got a message that there were too many ‘faces’, so that conversion was not possible. It was clear that some basic ‘editing’ was needed before I could start to use my ‘Fusion 360’ modelling tools to adapt the components of my downloaded horse. This sent me on a search for software that could help me to solve this difficulty and I found the very useful (and free) ‘Meshmixer’ program by ‘Autodesk’.  Some of the useful functions of this software are described below:
     
    Separating the three components using 'Meshmixer
     
    After opening the original model that I had downloaded from the ‘Cults’ site, I found that I could use the ‘Select’ tool in ‘Meshmixer’ to separate the three parts of the original model, so that I could work on each of them independently.
     
    Simplifying the model mesh
     
    The next step was to use the ‘Edit’ menu within the ‘Select’ tool in 'Meshmixer', to reduce the complexity of the mesh, choosing the ‘max deviation’ reduce target, so that deviations of less than 0.2 mm were ignored. This seemed a reasonable figure, to match the capability of my 3D printer. This process allowed me to reduce the number of facets on each component, so that they became suitable for importing into ‘Fusion 360’.
     
    Converting the Mesh
     
    Once the STL mesh file has been imported into ‘Fusion 360’, there is an option to convert a ‘mesh’ model into a ‘body’, which can then be operated upon by means of the usual ‘Fusion 360’ tools. During this process, I discovered that my ‘Windows 10’ operating system includes a 3D Viewer App, which not only displays STL files but also shows statistics, such as the number of faces and vertices in the model. The original downloaded horse had 50,474 triangles in its mesh whereas, after simplification as described above, this was reduced to 2,634 triangles.
     
    After carrying out these modifications, I had a model that could be imported successfully into ‘Fusion 360’, where I could start to make the changes needed for a ‘walking’ model.  Before I could do much more, however, I realised that I needed to make the upper body of the horse ‘hollow’, so that it could contain the tops of movable legs and their pivots. My aim was to provide the functionality contained in the the basic ‘4-legs Walker’ that I showed above.
     
    Making a hollow model with 'Meshmixer'
     
    I found that ‘Meshmixer’ contains a simple tool within the ‘Edit’ menu to make a mesh model ‘hollow’, with options to define the thickness of the remaining side walls and the complexity of the inner mesh. This procedure is illustrated below:
     

    Using Meshmixer to create a hollow model
     
    In 'Meshmixer', the inner mesh is described in terms of ‘mesh density’ so, by trial and error, I selected a value that seemed to match the number of triangles in the outer mesh.  Now, I could import the hollow mesh model into ‘Fusion 360’, where I could use the ‘Hole’ tool to make apertures in the sides of the horse body, to accept axles for the pivoted legs.
     
    Adding legs
     
    For the initial trials I created simple rectangular legs with open rings at the top to act as pivots – these were similar to the ones used by the ‘4legs-Walker.’ I reamed out the holes until the legs swung freely on 2 mm diameter steel axles. When printed, the upper body now looked like this:
     

    My 3D printed Hollow Body with Legs
     
    I did quite a lot of fettling of the various components, to make sure that the legs swung freely within the upper body shell.
     
    Lower Body
     
    I imported the original solid version of the lower body into ‘Fusion 360’ and used the ‘Split’ tool to cut off the original legs from this part of the body, just below the belly of the model. I then drew rectangles on the flat top surface of the lower body, to define where the movable legs could pass through, while limiting their angle of travel. I extruded these rectangles into apertures, through the depth of the lower body, using trial and error to adjust the size of these apertures so that they allowed an appropriate amount of free leg movement, fore and aft.
     

    My 3D Printed Lower Body with Slots
     
    Printing the Feet
     
    The shape of the feet is critical to the working of the model, so I started by modifying the ones used by the ‘4legs-Walker’, downloaded from the ‘Cults’ site. Because the lower surface has to be angled, I separated the feet from the legs and provided a flat upper surface to each foot, which could lie on the bed of my 3D printer, when I printed the feet ‘upside down’. I also provided a rectangular socket in the top of each foot to hold a leg securely.
     
    Assembly
     
    Once I had designed all the individual components in ‘Fusion 360’, I printed each of the components: upper body, lower body, head, 4 legs and 4 feet. As mentioned above, a considerable amount of trial and error was needed to achieve the clearances needed for free movement of the legs within a controlled arc of swing.  Fortunately, each of these small parts only took a few minutes to print, so it was easy to make successive ‘tries’.  I show below this collection of parts, as they emerged from the printer.
     

    My 3D printed ‘Walking Horse’ Components
     
    Lessons Learned
     
    I’ve learned quite a lot about how to modify a 3D-printable model downloaded from the web, by means of tools such as ‘Meshmixer’, which I hope will be of interest to other 3D modellers.
     
    Help Requested
     
    Unfortunately, though,  I’ve still not succeeded in achieving an effective walking motion so, if any of my readers can make useful suggestions, I’ll be very pleased to receive them.
     
    In the meantime, I’ll keep trying to find the ‘magic solution’
     
    Mike
  23. MikeOxon

    3D-printed Modelling Tool

    By MikeOxon,


    General
    For some time, I have been feeling dissatisfied with the shaping of the frames on my model of the broad gauge engine ‘Rob Roy’ but couldn’t think of any ways to improve them, with the limited tools that I have.  The construction of my model is described earlier in my blog.
     

     
     
    Recently I started to think about whether my 3D-printer might be able to help. I do like engines to be made of metal, so a complete plastic print wasn’t my favourite option, although I did find it a useful exercise for testing my modelling skills.
     
    I had the idea that it might be possible to make a tool or template, to help in forming brass sheet to the correct curved shapes. I couldn’t work from published drawings because I have modified the frames to suit some slightly over-size Tri-ang wheels, which I chose because they have the correct number of spokes for the GWR ‘Waverley’ class. These wheels are a very prominent feature of the prototype.
     
    My starting point was a JPEG image of the frames that I made for my model, which has some compromises in dimensions, to accommodate the wheels. It proved quite difficult to turn this into something that I could ‘extrude’ into a ‘solid’ model by using my 'Fusion 360' software.
     


    Rob Roy Frames (modified) – JPEG image
     
    Different software packages have their strengths and weaknesses. For this application, ‘Silhouette Studio’ has an excellent ‘trace’ function but has very limited export capability.
     
    My first step was, therefore, to open the JPEG image in ‘Studio’. One pitfall is that the image had be scaled to 72px/inch, which caught me out because I usually use 300 for printing. I was initially puzzled because the image appeared 4.2 times too big!
     
    Once I had a correctly-sized background image, I use the ‘trace tool’, with the various filters turned off. The result was an outline drawing, which I saved in ‘Studio3’ format.
     

     
     
    To get this drawing into ‘Fusion 360’, it needs to be converted to SVG, which proved tricky.There is, however, a website  that will do an on-line conversion of ‘Studio’ files to SVG format, so, by using this, I now had the drawing in a format that I could insert into ‘Fusion 360’. 
     
    In principle, the extrude tools in ‘Fusion 360’ can be used to transform an imported drawing into a solid object. In practice, however, my drawing turned out to have tiny gaps in the lines, which did not create the closed areas that are needed for extrusion to work.  There is an ‘inspect’ tool, which identified a very large number of places where such gaps occurred but I don’t know of any easy way to close gaps in ‘Fusion 360’, other than on a point-by-point basis. Since the gaps are very tiny, it is difficult to find where to apply the editing tools such as ‘extend’ and ‘join’ and, in some places, they did not seem to work on the imported drawing. Failures seemed to occur where lines met some types of curves and would not connect .
     
    I needed another piece of software, to try and resolve the problem. So, I opened my SVG drawing in ‘Inkscape’ and explored the various ‘repair’ tools in that software. The ‘edit paths by nodes’ tool revealed that there was a very large number of nodes in the traced drawing. The ‘simplify’ command on the ‘path’ menu did a good job in reducing these to a more manageable number. By zooming in on the drawing to look at the detail of the nodes, it was easy to see where some nodes did not link up and it was easy to move node points so that they ‘fused’.
     
    I re-saved the drawing and inserted the new version into ‘Fusion 360’. Overall, the situation was now much better in that the main area could now be selected as a closed object. The ‘inspect’ tool revealed just a few problem areas and it was now feasible to give these points individual attention. In some cases, it was quicker simply to delete a short section and replace it with new lines. This method was sufficient to ‘close’ all the separate areas.
     
    It was only when I came to transfer the design to my slicing software, ‘Cura’, for printing that I realised that the scale had somehow changed during the transfer from ‘Inkscape’ to ‘Fusion 360’.  In my previous work, I had always used DXF files from ‘Autosketch’ and these transferred correctly to scale. As a check, I tried saving the file in DXF format from ‘Inkscape’, which solved the scale problem, but the other problems of ‘loose ends’ appeared again and, in the end, I found it easier to re-scale the printer file within my ‘Cura’ software, before finally converting the model to ‘gcode’ for my E180 printer. The printed tool is shown below.
     

     
     
    For my purpose, the most important part is the curved top surface, which provides a firm base on which to construct my curved splashers.
     
    My first step was to glue a sheet of 10 thou (0.25 mm) brass sheet to one face of the tool. I used ‘UHU’ adhesive so that, after processing, the brass could easily be removed by immersion in hot water.  I then used my Dremel ‘Moto-Saw’ to make a rough cut around the main features. This wasn’t as easy as I had hoped, since the saw operates with a vibrating motion and tended to pull at the thin brass sheet. It was, however, adequate for making a rough outline, which I could then refine by means of jewellers’ snips..
     

     
     
    I found it easy to use the snips, now that the brass sheet was firmly attached to the tool, which I could hold comfortably during cutting.
     

     
     
    For the final trimming, to match the edges of the tool, I used a selection of needle files. Although the tool is, obviously, very soft, it was sufficiently firm to provide feedback when the brass edges had matched the tool surfaces.
     

     
     
    Once the frames had been shaped to my satisfaction, I started to add the curved top surface to form the splashers. For this, I used lengths of 5 thou (0.125 mm) brass shim. I used separate lengths for each section of the splashers, as I had done in my original model, but I feel it would be possible, with care, to fold the whole top as a single sheet. I provided a series of tabs along the back of the splashers that I folded down for attachment to the frame. Because the  tool is plastic that melts easily, I could not solder these tabs in situ but, once everything was correctly shaped, I could remove the components from the tool, by immersion in hot water, and solder the parts together subsequently.
     

     
     
    I treated this as a ‘practice run’ and propose to try it ‘for real’ on some future engine builds that are in the pipeline. In fact, having looked at my ‘Rob Roy’ again, it doesn’t look nearly as bad as I thought and I shall finish it in its present form, while using the new techniques to build different designs.
     
    Having got this far, I decided to see how much extra work was needed to create a complete 3D-printed frame. The answer was not a great deal and, as a training exercise, I made a complete set of frames and splashers with ‘Fusion 360’, as shown below.  It was necessary to extrude selected parts of the drawing by different amounts to create the 3D structure.
     

     
     
    I took the opportunity to add sand-boxes and rudimentary springs to my original drawing. One advantage of using computer-aided design is that producing a pair of right and left handed frames is simply a matter of pressing a ‘mirror’ button! So, here’s a pair of frames, straight from the 3D-printer, with Tri-ang driving wheels in place on one side.
     

     
     
    Although the splasher tops are rather ‘thick’, to allow successful printing, they are also surprisingly robust and this would be a feasible method to use … providing you are content with plastic engines.  I intend to continue with brass construction but with the assistance of 3D-printed tools, to help in forming complex shapes.
     
    Mike
     
     
     
     
     
     
  24. MikeOxon

    A 'Virtual' Distraction

    By MikeOxon,

    A new distraction has been keeping me away from the modelling bench. There’s not much ‘Broad Gauge’ in this post except that it was triggered by spotting this entry  in Annie's Virtual Pre-Grouping Layout & Workbench thread
     
     
    I’d never given much attention to train simulators before, although I have done quite a lot with the Microsoft Flight Simulator. Now, prompted by Annie’s posts, I felt that I should look more closely, so I followed her suggestion to try downloading Trainz-A New Era (T:ANE). It seems that I chose a good moment, since the software was on offer at 10 USD (around £8), which seemed very little for such a sophisticated product.
     
    I soon found myself thinking that it was a bit too sophisticated for me! The basic set included the entire East Coast Main Line (ECML), with a Deltic-headed train to drive along it. It worked and the scenery was remarkably detailed – much more so than is usual in FlightSim - but with a corresponding ‘hit’ on computer resources. The program needs a lot of memory and a powerful video card to run in a high level of detail!
     
    The ECML and Deltic diesels are not my usual modelling territory but I noticed there was a free download of the West Cornwall lines available from the Trainz store. This seemed much more my territory, although I also remembered that ‘free’ software often implies ‘can of worms’.
     
    I was a little puzzled when I first loaded it (which took a very long time) to find that the only ‘scenario’ offered was ‘Quick Drive – choose a train’. I found a list of trains and chose King George V located at Penzance. A nicely detailed scene appeared, including a red signal in front of my train that didn’t seem to be changeable!   Ignoring it and driving forward started fairly well … until I found myself being diverted into a dead-end siding!
     

    Driving a ‘King’
     
    So started a rather irritating learning curve. It appears that this ‘layout’ is populated by trains that are pre-set to run a pre-determined timetable. While a lot of the scenery looked good, there were some strange juxtapositions, such as Network Rail signage in what was supposed to be a 1930s scenario. Other odd things appeared too, like signals that showed a green light with a horizontal semaphore arm ... well, it was free!!!
     

    Anachronism at Penzance Station
     
    Part of my trouble was that I had jumped into a later version of some software that started in more basic form, several years ago. I began to find that a lot of the basic information I needed was only to be found by looking at earlier versions of the software and so I gradually learned how to place a train of my own and run it along the track. I think it will be a long time before I can try anything like back-dating the system to Broad Gauge days!
     
    Despite the frustrations, I have been admiring the diversity of the scenery, including this view of Truro Cathedral from the viaduct just outside the station:
     

    1486 with Truro Cathedral
     
    Now it’s time to put all my modelling, both virtual and actual, on hold while I address family matters over the holiday season. In the new year, I shall hope to get back to making some progress on my ‘real’ Broad gauge modelling.
     
    With my best wishes to my readers for Christmas and the New Year.
     
    Mike
  25. MikeOxon

    A Bit about the Track

    By MikeOxon,


    general
    As I mentioned in my first entry in this blog, my layout started many years ago as a Hornby Dublo layout for my young son. The plan was taken directly from the Hornby Dublo Handbook of 2-Rail Track Formations (1st edition), as shown below, drawn using SCARM software
     

     
    Original Track Plan (as built in 1979)
     
    This track plan formed the basis for a small, simple layout, to which I added a narrow gauge section (009) at a higher level, for additional interest. The upper level hides the 'round and round' nature of the main line, while leaving the station, at the front, and goods yard visible, for scenic modelling. There was never anything very prototypical about the layout and I treated it mainly as a framework for developing scenery and 'vignettes' for photography.
     
    When I returned to this railway, a couple of years ago, I decided to use it for the Victorian designs, which I was interested in constructing. One major limitation in operating the track was the lack of a passing loop on the main circuit, so I decided one could be provided by replacing one of the points on the cross-over loop with a three-way point. Again, by using the SCARM software, I found that I could incorporate a Peco SL-E99 'electrofrog' point, without making major changes to the overall layout.
     

     
    Revised Layout Plan (including 009 section)
     
    I marked the positions for the new track on the baseboard, assisted by use of the Peco templates, as shown by the following photo of the 'work in progress'.
     

     
    Marked-up Baseboard and Templates
     
    The new point required two point motors and switches, to control the live-frog polarity. For these functions, I used SEEP motors, with integral switches. For ease of installation, I mounted the motors onto small rectangles of printed circuit board, together with block connectors. This meant that all the soldering could be done on the bench, with the connector blocks used subsequently, to hook up to the wiring under the baseboard.
     

     
    SEEP Point Motor Module
     
    Since I already had a 'hand-held' controller, I decided to adopt a similar principle for operation of the point switches. I mounted the six point switches needed on my layout in a small plastic box, from Maplin, and connected this to the layout via a multi-way lead, taken from a parallel-port printer cable.
     

     
    Remote Controller for Points
     
    The connections from the point motors were all brought to a common board, carrying three sockets to connect controllers for points, mainline, and narrow gauge, respectively. Again, I designed the board so that most of the wiring could be done on the bench, with just the final hook-ups having to be done under the baseboard. All the wiring is colour-coded and labelled to assist the final assembly.
     

     

     
    Two views of the Control Panel
     

    Points Wiring Plan
     
    Once all this was in place, I had the basis of a layout to display my Victorian stock
     

     
     
    Mike
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