I make no secret of the fact that I find it hard to keep up momentum once I’ve completed the main structure of an engine and have to think about adding the various small details.

 

Gooch Goods ‘Tantalus’ – bare bones

 

One particular irritation with my Gooch Goods was that there were some things that I could easily have included in the main 3D-printed components but had neglected to do so. This was largely because, like most of my projects, it was experimental in that I was exploring new methods of construction.  In fact, I had found a simple and sturdy method to construct the engine around a brass tube for the boiler barrel.

 

When it was pointed out that the external dimensions of the boiler should include the thickness of the cladding, I simply added a 3D-printed sleeve, which also carried details such as the boiler bands. Since then, I have found some text about boiler cladding in an early book about locomotive construction: ‘Railway Machinery’ by D.K. Clark (1855) “Cleading [sic]. The boiler should be completely enveloped, at all approachable points, in a non-conducting garment, consisting of several plies of felt, covered with ¾ inch pine battens grooved and tongued, and finished with sheet iron, No. 17 wire gauge, strapped well down.” This text indicates that, in the early days, the cladding was rather thin and that its main purpose seems to be have been to protect personnel, rather than reducing thermal losses.

 

Another surprising statement from the same book is: “There should not be any brass ornamental work about locomotives; as, to appear well, it requires continual cleaning.” It seems that, as early as 1855, cleaning was beginning to be considered an unnecessary expense!

 

Detail Painting

 

One advantage from having built my boiler with removable cladding is that I could paint the brass fillets, at the firebox and smokebox ends, with no risk of over-spill of paint onto the cladding! One of the many ‘fiddly’ details to be attended to was painting the ‘bright-work’. Fortunately, I still have steady hands, although I need to work under an illuminated magnifier to be able to see the details clearly, as shown in the photo below. Credit must also go to my excellent Winsor & Newton series 7 brushes, that maintain the fine tips that are essential to be able to place paint accurately.

 

 

I used to prefer enamel paints for models but now find that acrylics have advantages, although they have to be used in a different way – more like water colour painting. The important thing is to keep the brush suitably moist from a clean pot of water to hand. I then add pigment to the tip of the brush and sweep it across the surfaces, making sure that they stay moist. Keeping the surface wet, I add pigment until the depth of colour is sufficient.

 

The ‘Rustoleum’ ‘Dark Green’ I used is a water-based paint and I added black to achieve my required tint. It seems strange that the colour, as I perceive it, appears to become less blue as I add black! As I mentioned in my post about ‘Rob Roy’, I find the colour feels ‘right’ to me for early GWR locomotives, although it is very different from the later chrome green.

 

For comparison, I photographed one of my Gooch boilers, painted in my interpretation of ‘Holly Green’, placed in front of my ‘1854’-class saddle tank painted in ‘Precision Paints’ 1881-1906 GWR Green.:

 

 

I also used acrylic paint for the outside splashers on the goods engine, which have half-etched central recesses between the upper and lower edge beading. These are components from the Broad Gauge Society (BGS) kit for the Gooch Goods and I found it easier to paint this detail while the frames were still on the fret, as shown below:

 

 

 

Adding details

 

An important omission in my initial construction was that I failed to add a plinth for the safety-valve cover on the top of the firebox. It was a new challenge to work out how to add this feature on top of the curved surface of the firebox.

 

The method I devised, using ‘Fusion 360’ software, was to create an ‘offset plane’ at an appropriate distance above the crown of the firebox cladding. I then drew a square (using ‘sketch’ mode) on this plane and used the ‘push/pull’ tool to extrude this square to meet the curved surface of the firebox. Finally, I used the ‘hole’ tool, to make a central hole to accept the spigot on the base of my lost-wax casting of the safety-valve cover. My method is illustrated by the screen-shot from ‘Fusion 360’, shown below:

 

 

Because of my modular method of construction, it would have been easy to replace the original firebox with this revised version, although I had already completed some tricky painting of the original firebox, including the polished brass trim.

 

When I added this extra plinth, however, ‘Fusion 360’ offered the option to make the feature a new ‘body’. This new body could be separated from the original firebox and exported as a separate file for 3D-printing. I was somewhat sceptical that such a small item would print successfully but decided to have a go.

 

Considering that my ‘Geeetech E180’ printer is an inexpensive machine, I was pleasantly surprised by the result. Two adjustments to my usual print routine helped to capture the detail: Firstly, I selected ‘extra fine’ in the ‘Cura’ slicing software, which reduces the layer height to 0.06 mm and, secondly, I reduced the ‘line width’ to 0.3 mm. The ‘help’ information in ‘Cura’ suggests that, even though my printer nozzle is 0.4 mm in diameter, there can be an advantage in selecting a smaller line-width and this appears to have been borne out in practice, as shown below. These changes extend the printing time by at least a factor of two but, for small items like these, the time is still only a matter of a few minutes.

 

 

These plinths are suitable for both my ‘Rob Roy’ and ‘Tantalus’ models.  After cleaning up the stray bits of filament, I painted the plinths by threading them on to a cocktail stick then brushing all the exposed surfaces.

 

 

 

Engines Compared

 

As I stated at the beginning of this post, the aim of my models is to capture an overall impression of the prototype, rather than the small details. Apart from a few replicas, the Broad Gauge is well beyond the memory of any living persons, so making models that help me to appreciate the ‘look and feel’ of the period is my strongest motivation.

 

In the case of my current models: the Waverley-class ‘Rob Roy’ and the Goods engine ‘Tantalus’, I have been struck by the difference in ‘grandeur’ of the two designs, despite the fact that they both carry the same type of boiler.

 

Two factors strike me as important: the more obvious being the size of the exposed driving wheels on ‘Rob Roy’, which conveys an immediate impression of power and speed. As a consequence of these large wheels, the boiler had to be pitched considerably higher on this engine than on the smaller wheeled Goods engine and this second factor adds to the imposing impression given by the express engine.

 

In fact, the difference seemed so marked, when I first placed the models together, that I made copies of the relevant drawings and placed them head-to-head, in order to confirm that my impression from the models is correct.

 

Drawings Comparison – Waverley class and Gooch Goods

 

And below, a similar comparison between my two models:

 

Waverley 4-4-0 and Gooch Goods compared

 

Not complete yet, I fear, but I’m pleased to see that the broad outlines reflect some of the ‘spirit’ of the prototypes

 

My model of a Gooch Standard Goods

 

Two sprues of lost wax casting for lamps, whistles, and injectors have just arrived from the Broad Gauge Society, so my next task will be to add these small fittings. I also have a nickel-silver fret for coupling rods and some valve gear parts.

 

Mike