MikeOxon

Now found a drawing in Mike Sharman's selection of locomotive drawings by Oakwood Press. Mike

The outer edge of the lining appears very bright in the Snow Hill photograph, which suggests it was white, as in Wolverhampton livery. The orange hue of Swindon lining does not render well in photographs taken with the emulsions of the time, which were insensitive towards the red end of the spectrum. Mike

Since this thread has come to life again, I have restored images in my own posts that were lost in the 'great extinction'. In particular, this one may be of continuing interest: Mike

"Today's blog post introduces a new locomotive, definitely not well-known as others but still as beautiful" I suspect it's little known because it never belonged to the GWR, so is missing from many books. It seems that it was first used on the Bristol and Gloucester Railway, where it was named 'Cheltenham' and was built by Stothert & Slaughter to designs by Bury. Where did you find the illustration you used as the basis for your model? I couldn't find one on the web. Mike

Many thanks - I see you mention Roblox in the intro. to your blog. I had wondered about those coupling blocks! So, do you do all the model design within that software? I assume that it's fairly limited, in comparison with dedicated CAD software.

One comparison I would like to have made was with Stephenson's 'Rocket' but I couldn't find my old Airfix/Dapol 4mm-scale model. I have, however, found .stl files on the 'Printables' website, for a 'Rocket' model by Václav Krmela. I imported his files into 'Fusion 360', scaled them to 4mm/ft, and placed his model alongside the Trevithick model for the following comparison: (Rocket model shown without tender) An important step in the 'locomotive line of development'. Mike

If only it were! As it stands, it wouldn't survive for 30 seconds in the grandchildren's hands.

I'm currently reading Anthony Burton's 'Richard Trevithick - Giant of Steam'. James Watt had tried to put a stranglehold on steam engine development though the use of far-reaching Patents. Trevithick's use of 'strong steam' was the break-through that moved things on. He created the steam engine as we know it. That was indeed real genius

I tried Night Café a while ago and didn't manage to get anything I wanted. When I tried to create some early railway scenes, they all looked like something from a Wild West movie. I gave up rather quickly but you make me feel I should have persisted. The vehicles look very odd though and nothing like what appear in real 'old London' photos.

Good to know this is still running. Those etches look very nice but you will have fun assembling all those small parts! I find that, when doing a repetitive job, I seem to 'program' myself into a steady routine, so that it becomes almost automatic to put them together - good luck and I hope the show goes well! Mike

Thank you @ChrisN. I must give credit to the Czech modeller who placed his .stl files on the 'Printables' website for the overall design of the model. I was, frankly, amazed by how well it printed at only about 20% of the original size. With a little more attention to detail, mainly in the design of the cross-head, I think mine could have been a 'rolling' model. It has served my purpose, though, by enabling me to place the model alongside early GWR engines.

indeed it is - and it almost drove me to distraction at times. I dropped the chimney just after assembling it to the curved pipe at the base and then could not find it, even with a finger-tip search of the floor! The glue had not hardened and it had stuck itself firmly to the side of my sock!!! Stick to the virtual world where such things don't happen 🙂

I’ve now managed to produce a set of ‘printable’ parts from the original download from the ‘Printables’ website described in my previous post. I’m still puzzled by the theories on exactly which of Trevithick’s locomotive engines was actually used for the Penydarren trial, which was the moment in history that put the steam locomotive on the map. There is a print in the Science Museum collection, said to be the Penydarren engine but it has been discredited because, according to the attached scale, it shown an engine on a 3-foot gauge track. When I compared this print with the illustration in Francis Trevithick’s book, however, it was obvious that they were extremely similar, although the book states that gauge was 4’ 4”. On further inspection, I realised that the Science Museum print became a very good match (not identical but very similar), if I increased the scale of the print to correspond with a 4’ 4” gauge. Can it really be the case that subsequent authors have been misled by the scale appended to the drawing? I’ve seen so many examples of a wrong scale on a drawing to feel that it is not that unlikely an occurrence! Incidentally Francis Trevithick, son of Richard, was himself a railway engineer, having been appointed Locomotive Superintendent to the Grand Junction Railway at Edge Hill, Liverpool, in 1841. I mention this to show that he was very knowledgeable about engines Printing my model parts Making the parts downloaded from the ‘Printables’ website printable at the smaller scale of 4mm/ft did not prove to be too arduous. I made all the gear wheels a little thicker by a simple scale change in the ‘Cura’ software. The boiler and chimney were both too thin-walled to print, so I created new versions as simple cylinders in ‘Fusion 360’. The triangular front support for the piston-rod was also too fragile, so I re-drew a stronger version. After assembling all the parts together, I made a ‘rendered’ view of the model within ‘Fusion 360’. The piston-rod and slide bars are indicated as brass rods, which is how I intended to create them for the physical model. Model of Trevithick’s engine rendered in Fusion 360 Apart from these rods, I transferred all the revised files from ‘Fusion 360’ to the ‘Cura’ slicer program and thence to my printer. In the case of small parts, which take only a few minutes to print, I collected several items together as a single ‘print job’. For example, all the gear wheels were printed together in the printer build plate. Various wheels and gears printed together – on my printer bed A curious observation was that, in a couple of cases, small parts which did not print cleanly the first time, gave a far better result when I immediately repeated the print, over the same location on the printer bed (i.e. no change to any of the print parameters). Could the fact that the print head was still warm have resulted in a cleaner start to the re-print? Assembling my model When I first viewed the collection of tiny parts that I had printed, I quailed at the thought of ever being able to connect them all together! Fortunately, I have a good illuminated magnifier and, very importantly, have recently had cataract surgery that has restored my acuity of vision! I’m also pleased to have found that my hands are still steady enough to thread small-diameter rods through barely visible holes in tiny parts!!! Of course all you 2mm FS modellers will wonder what I’m talking about but it was a delicate-seeming operation for me to attempt. I don’t know if Julia Adams still visits this site but it was seeing her demonstrations at various shows that assured me that such fine work is possible. So, where to begin? I decided to try threading the main drive-shaft through the lugs on the boiler end-plate, to connect to the flywheel on one side and the primary gear wheel on the other. It turned out that a 1 mm diameter brass rod slid through the lugs, after just a slight touch with a reamer, so I soon had these parts joined together: My Primary Driveshaft Assembly I realised that there is a boiler extension below the drive shaft, which may explain why the boiler length is described in the references as being 6 feet. This extension presumably accommodated the curved end of the return flue inside the boiler. This initial step demonstrated that there was a good chance that other shafts and gears would all fit together so, with a little more confidence, I assembled the main driving wheels onto their 2mm diameter steel axles. In the prototype, the axles were fitted to a very basic wooden ‘boiler truck’, to support the main components of the engine. This illustrates the concept that Trevithick had of designing his engines as ‘multi purpose’ machines. In a letter to Mr. Giddy dated February 22nd 1804, Trevithick wrote “An engine is ordered for the West India Docks, to travel itself from ship to ship, to unload and to take up the goods to the upper floors of the storehouses by the crane, and in case of fire to force water on the storehouses. The fire is to be kept constantly burning in the engine, so as to be ready at all times.” I fitted a second 1 mm diameter rod into the raised mounting on the side of the boiler, to carry the ‘intermediate gear’, which conveyed the drive from the primary gear to the gears on the faces of the driving wheels. After setting the model boiler onto its ‘boiler truck’, this part of the assembly appeared as shown below: My 3D-printed Boiler on its wheeled carriage I was pleased to find that the gears meshed together well, so the next step was to attach the boiler end plate, carrying the primary drive shaft: and its gear wheel. Assembly of the Main Gear-train These parts all fitted together well, so it was time to look at the thorny issue of the cross-head and its associated support structure. I decided to attach all the relevant parts to the end-plate of the boiler, before adding the completed assembly to the boiler itself and the main gear-train. I started by cleaning up the details on the end plate of the boiler since, in the small scale, some of the detailing had become a little obscured by stray filament, where the printer had attempted to negotiate some very convoluted paths. Once this was done, I used a reamer to open out the central hole in the end-plate to accept the 1 mm diameter brass piston-rod. I thought that the printed cross head might prove too frail but, in fact, the central hole opened out successfully, by careful use of a 1 mm drill in a pin-vice. I slid the end of the piston-rod into this hole, adding a drop of super glue to keep it firmly in place. For the two slide bars on either side of the piston-rod, I used 0.5 mm diameter brass rods. Again, I used a reamer to help insert the rods into the appropriate sockets on the boiler end-plate and in the cross head. I cut two slightly over-length rods and slid them into their places alongside the piston-rod. As the last part of this assembly, I added the rather fragile print of the triangular support structure. The two arms fitted into two notches on the sides of the end-plate. I put a small dot of gelled-superglue into each of these notches and then manoeuvred each of the arms into place, in turn, holding them until the glue ‘caught’. After re-checking the alignment of all these parts, I set the whole assembly on one side, to allow the glue to harden. My assembly of the Cross Head and its associated Rods. To call this a delicate operation would be something of an under-statement! The end bracket holding the outer ends of the slide bars is the smallest item I've ever printed and the main problem was keeping it from the clutches of the carpet monster😆 I show it being held on the shaft of a reamer, against my thumb for scale: End support held on a reamer Note the two small ‘ears’ above the bracket, which replicate those on the cross-head. These are supports for rods to operate the four-way cock by means of tappets, moved by the cross-head to change over the cock as the piston nears the ends of the cylinder. They were also used when starting, to ensure that this single-cylinder locomotive started to move in the desired direction. I’m afraid I shall omit these parts, as they are simply too fine (for me) to create at 4mm/ft scale. The next items to add to the end-plate were the chimney and its right-angle connecting pipe. A key part of the original design was that the exhaust steam from the four-way cock was directed up the chimney, so that the steam blast helped to ‘draw’ the fire and so improve the steaming of the engine. As I had anticipated, the tall slender chimney did not print very smoothly and, a length of metal tube would be a better solution. The printed one serves the purpose of showing the overall appearance of the engine. After gluing this assembly to the end of the boiler, the remaining task was to add the long connecting rods, between the cross-head and the drive-shaft at the opposite end of the boiler. I couldn’t manage to fix pins into the end of the cross head so the rods are glued together here. The other ends are pinned to the flywheel and primary gear crank. In practice, although the cross -head will slide, the movement is too tight for this to be considered as a working model … perhaps, next time, with a few improvements to those components that are really insufficiently robust at this scale 🙂. So, at last, the rather spidery contraption looks as shown below: My 4 mm/ft scale model of a Trevithick locomotive c.1803 So, why did I do it? Partly of course because it was there but also, I wanted to place the earliest GWR engines within the context of what had gone before. Even the earliest GWR engines were rather late on the scene – 35 years later than this Trevithick engine, which is rather a long time in a period of rapid technological development. I can write about dimensions and show models against a ruler but a much more ‘real’ impression is formed when I place my models from different periods alongside one another. Below I show the Trevithick locomotive in context with some of my early GWR models placed on the same table. I believe this brings home much more vividly what progress was made during the first half of the 19th century! Mike

The boiler was pretty large (6' x 4' 3" dia) and not full of tubes either, which may be relevant factors.

I agree, Jeremy, that there are many puzzles remaining concerning exactly what happened at Penydarren. I also agree that all the other drawings I have seen show the flywheel crankpin aligned with one of the spokes but there could have been a separate crank as you suggest, since that is the arrangement on the other side of the drive shaft. One account claims that the rails through the tunnel were moved and that this led to an argument over the prize being awarded. It might mean that the rails were offset to give maximum height over the flywheel. It is probable that the chimney was removed or lowered, as the boiler would retain sufficient steam for the passage through the tunnel. There's a passage in a letter to Mr Giddy that says: "It is above nine miles , which we performed in four hours and five minutes. We had to cut down some trees and remove some large rocks out of the road. The engine, while working, went nearly five miles per hour ; no water was put into the boiler from the time we started until we arrived at our journey's end ". That was a very long time to travel 9 miles and allows for plenty of stoppages to deal with various obstacles. Regarding your books 'wish list', the biography by Francis Trevithick can be downloaded free from the Internet Archive website. Mike

Indeed so - I didn't attempt an overview of his career, which is described in several books. For such a talented person, it seems rather sad that his life ended in poverty.

Thank you for this information, @Northroader. I have now had an opportunity to look at Marshall's book and it contains a lot of interesting information. I also note that a footnote at the beginning of the chapter about Trevithick refers to the biography by Francis Trevithick, stating that "' Much of this chapter is derived from it.". Nevertheless, there are many interesting additional items, such as this quotation from a communication by Mr. Reynolds Anstice ‘ then in charge of Madeley Wood Co.: "There was a beautifully executed model of this locomotive engine in my Uncle William Reynolds' possession, which was given me by his widow, the late Mrs. Reynolds, of Severn House, after his death. I was then a boy, fond of making model engines of my own, and I broke up the priceless relic to convert it to my own base purposes, an act which I now repent as if it had been a sin. The Coalbrookdale engine is, I believe, the first locomotive engine on record intended to be used on a railroad." This seems clear that the Coalbrookdale eingine was a locomotive and not just a stationary engine, although Trevithick himself frequently referred to his compact high-pressure engines as 'general purpose' machines. Mike

I have written about Knee's furniture van in my blog - it is said to have been the first to be carried by rail. Mike

You have an interesting collection of early broad gauge models. I would welcome more information about the software you use to generate the 3D views. The rendering does leave the colours looking rather 'flat', especially the bright-work, which looks badly in need of a polish! I think this is a fascinating period of railway history that deserves to be better known and models are a good way of raising awareness. Mike

If you had said chocolate instead of brown and cream instead of white, everyone would have been interested 😄

I would have suggest Mavis and Doris but then realised they are Welsh ladies, so I have no idea. I sometime buy odd figures, intending to use them later, but they seem to escape somewhere and I never find them when I want them! I know Brunel is lurking somewhere ...

I must take a closer look at what's on the simulators - lots of interesting stuff there! Steve seems to have chosen the same design that I did, with chimney and cylinders at the same end - not so convenient for firing on the move, so it's not surprising that Trevithick changed the layout later on ... although we don't seem to know exactly when. I read an amusing passage in his son's book that "It was a saying in Cornwall that Captain Dick would make a capital working steam-engine from the scrap heap or castaways of ordinary engineers.", so there are probably lots of unknown variants. Thank you, Annie, for showing your appreciation. I'm sure that some modelling of the South Wales tramways would be fascinating. I've walked some of the trackbeds and they pass though some dramatic scenery. I've already tried printing some of the gear wheels and they have come out rather well (shown un-fettled), despite their small sizes. Some other parts are going to need a re-design for printing in 4mm scale, though. Mike

Thanks Chris - the title was a last minute idea as I was posting. The research took quite a while, as there's a lot of conflicting information out there! I'm realising that history is a very difficult subject for research. There used to be an Airfix kit and I'm not sure which prototype that was based on.

I have not forgotten about my plans to create a diorama, as described in my Broad Gauge blog. While I was researching the early days of the GWR, however, I found myself thinking about what had gone before – back to the ultimate pre-grouping period! This led me to Trevithick’s engines, of which I photographed a replica at Blists Hill Museum near Telford: Trevithick replica at Blists Hill Museum Trevithick was a remarkable inventor but, sadly, not a good businessman. He not only demonstrated, by 1802, that a compact high-pressure steam engine could be adapted to both road and rail uses but also that such a vehicle could be propelled by adhesion alone. In his Penydarren locomotive of 1804, possibly his most famous design, he turned the exhaust steam up the chimney, so creating the ‘blast pipe’ which was to prove an essential component of later locomotives. He sold all the rights to his designs and emigrated to South America to seek his fortune. He eventually failed there and died in poverty, back in England. His son, Francis, wrote a two-volume biography ‘Life of Richard Trevithick’, published 1872, which describes his father’s life and inventions. In Vol.1, page 181, there is an illustration of the Tramway engine that was built for South Wales in 1803: Next, as so often seems to happen when I start a new research project, an entire ‘can of worms’ began to open up! The book also notes, however, that “particulars are taken from Trevithick's letters where other evidences are conflicting . It is probable that more than one tramroad - engine was constructed in Wales at that time.” The dimensions listed above do not correspond with the associated drawings! For example by scaling from the drawing, if the wheelbase is 4’ 1” then the boiler is only about 5 feet long, while the flywheel is about 8’ 9” diameter, so there is no way it could have fitted through the Plymouth-works tunnel on the Penydarren tramway! Later in the book, there are references to three different engines, including the one that I saw (in replica) at Blists Hill museum, Coalbrookdale. “We have no account of the railway work done by the Coalbrookdale travelling engine of 1802. The Welsh tramroad - engine of 1803 took a gross load of 25 tons, at the rate of four miles an hour, over a bad road, with sharp curves and stiff inclines, and without load ran at a speed of sixteen miles an hour. The Newcastle locomotive of 1804 was, in general outline, similar to the Welsh locomotive, but in detail superior. The wheels were to run on rails instead of trám-plates, and were 9 inches farther apart than the Welsh locomotive, giving increased steadiness. The boiler and return tube were wholly of wrought iron; the fire -door and chimney were at one end of the boiler, and the cylinder and guide-rods at the other end, giving more room to the engineman than on the Welsh locomotive, which had all those things at one end of the boiler. The cylinder of the Newcastle locomotive was of the same size as the Coalbrookdale engine of 1802 , being 7 inches in diameter, with a 3-feet stroke, and therefore was probably made at Coalbrookdale, from Trevithick's drawings and patterns of 1802, with its regulating blastpipe and steam of from 60 to 145 lbs . on the square inch .” At this point, there is even a Swindon connection, as shown by correspondence between Joseph Armstrong and Francis Trevithick: “F. TREVITHICK , Esq . May 10th, 1870 DEAR SIR, By this post I have forwarded a tracing of the old locomotive for Mr. Trevithick, and likewise some copies of an extract from the Gateshead Observer.' They would have been sent ere now, but I have had some difficulty in procuring an original from which to get a tracing, and have also spent time in hunting up this extract, and having it reprinted . Yours truly, JOSEPH ARMSTRONG Esq, Swindon.” In Plate V. , a is a steam-cylinder 7 inches diameter, 3 -feet stroke , fixed in the boiler ; b , piston-rod ; c, crosshead ; d, guides ; e , stay ; f, connecting rod ; g, crank ; h, driving axle ; i, fly-wheel ; j, gear-wheels ; k , four driving wheels, 3 feet 1 inch diameter, 4 feet 8 inches from centre to centre ; 1, four-way cock ; m, lever for working cock ; n, plug-rod ; o , cylindrical wrought- iron boiler, 4 feet diameter , 6 feet 6 inches long ; p, firegrate ; q, return fire - tube of wrought iron , 2 feet 3 inches diameter at the fire -door end, 1 foot diameter at the chimney end ; r, chimney ; s , fire-door ; t , railway of longitudinal timbers, 3 inches wide, 4 inches deep ; u, cross-sleepers, 4 inches wide , 3 inches deep ; 1 foot 1 inch apart ; gauge between wood rails , 4 feet 10 inches ; weight of engine in working order, 4 tons. Trevithick's 'Newcastle' engine After searching for more information, I found Anthony Dawson’s much more recent book ‘Before Rocket: The Steam Locomotive up to 1829’, published 2020, in which Chapter 1 reviews Trevithick’s work between 1802 and 1814. This text agrees that there were at least three similar locomotives. Dawson points out, however, that the Penydarren locomotive “was built to be convenient for the driver to work the engine and for the witnesses to see what was going on” He suggests that “this would probably rule out the cylinder being at the same end as the chimney. Thus, it is more likely that the Penydarren locomotive had the cylinder at the opposite end to the chimney and firebox, somewhat analogous with the Gateshead [Newcastle] Engine.” I do not know why he discards Francis Trevithick’s description and statements in reaching this conclusion, since the earlier work appears to be clear about the differences between the two engines. There is also the matter of a ‘replica’ built by The Museum of Wales (Waterfront Museum, Swansea), completed in 1981. Their guidebook states “that the replica was built working from Trevithick’s original documents and plans (now in the National Museum of Science and Industry).” This leaves the question “which plans?”. Their ‘replica’ places the chimney at the opposite end of the boiler from the cylinder, unlike the illustration in Francis Trevithick’s book but similar to the later Newcastle engine Perhaps I am missing some recent piece of scholarship but it is hard to see why the layout of the later Newcastle engine was preferred for the Welsh replica over Francis Trevithick’s 1872 description of the Welsh engine. Francis T. did, however, note that there was conflicting evidence and that “It is probable that more than one tramroad-engine was constructed in Wales at that time”. As I noted above, the engine, as drawn in his book, could not have run through the tunnel on the Penydarren tramway, although reducing the size of the flywheel would be a relatively simple modification. It seems that, after a lot of reading and thinking, the can of worms remains open! Creating a Model Naturally, I felt the need to create my own model but then I found a 3D printable design, created for the Prusa printer on the ‘Printables’ website This work is licensed under a Creative Commons (4.0 International License) Attribution—Noncommercial—Share Alike @ThorinOakenshield. This model, however, is a much larger and more sophisticated model than my own usual designs but I thought I might re-scale and simplify the design. Then, there is the question of ‘which engine does it represent?’ I tried my method of overlaying the drawing on p.181 of Trevithick’s book over a still from the video of the ‘Printables’ model and … in all the major respects they fit well together! (note that the video image is not quite ‘side-on’) Overlay of Trevithick drawing (red) on ‘Printables’ model So, whether or not this is actually the Penydarren engine or another Trevithick prototype, I feel that I am close to the appearance of one of the very first locomotive engines ever to run on rails! I decided to reduce the dimensions of my version, to fit a 4’ 4” gauge trackbed in 4 mm/foot scale, as the track gauge seems to be the only firm figure we have! To do this, I imported the drawing on p.181 of Trevithick’s book into ‘Fusion 360’ as a ‘canvas’ and then scaled it to the correct gauge at 4mm/foot scale. This confirmed the wheel diameter as 15 mm (prototype 3’ 9”). Drawing from Trevithick's book scaled in Fusion 360 Next, I loaded the .stl file for the wheels, downloaded from the web, into ‘Fusion 360’ as a ‘mesh body’. I laid this body over the above drawing and adjusted the size until the wheel diameter matched the drawing. This needed a scale factor of 21.34%. I imported all the .stl files for the web model into the ‘Cura’ software and re-sized them all by the same scale factor. Then I loaded all the re-scaled files into ‘Fusion 360’ as mesh bodies. I could then move each of the parts within ‘Fusion 360’ into its appropriate location around the boiler, as shown below against the ‘canvas’ backdrop: ‘Printables’ files, re-scaled and loaded into Fusion 360 This confirmed that the re-scaled parts should all fit together as required. It also indicated, however, that some parts would be too thin to print successfully at the reduced scale. In particular, the boiler casing would be far too thin, so I decided it would probably be easier to design a new part for this component and, maybe, for some other parts as well. The next step will be to review all the parts for their suitability for printing at 4 mm scale and make modifications where necessary. In the meantime, I show a couple of 3D views of the model, rendered in ‘Fusion 360’: Two rendered views of 3D-model assembled in Fusion 360 from ‘Printables’ files Mike

Looks good! One of my favourite engines, especially since I know that my wife's Great-grandfather drove it! Looking forward to seeing what you do next 🙂 Mike