At the end of the previous post I had printed a set of parts, which needed to be assembled into the complete carriage. I must admit that it was a bit of a shock to see how tiny some of the parts can be in reality, when they had looked quite substantial on the computer screen!
The springs were by far the smallest parts but I had chosen to print them separately so that they could lie flat on the printer bed. This orientation ensured that the hollow centres of the elliptic springs would print cleanly. I printed several, for experimental purposes, since they only take a minute each to print.
Initially, I tried fixing them by using super-glue but the contact area was too small and there was no simple way to hold the mating parts in their correct orientations while the glue hardened. I therefore turned to another method that I have used before on several models: using a fine soldering-iron tip set to 200°C. I could comfortably hold the parts by hand since, unlike metal, the resin has low thermal conductivity. A quick slide across the joint with the iron tip and the small parts fused almost instantly, to create a remarkably strong joint.
A better method might be to use one of the 3D printer pens that are now available, Such a pen could also be used to add differently coloured details. Possibly a future purchase!
Fusing Small Parts with 200°C Soldering Iron
I was very impressed by the fidelity with which my rather basic printer had created the complex 3D structures that make up the swivelling fore-carriage, as shown in my previous post.. In my very first post about 3D printing, I wrote “I wasn’t looking for anything particularly sophisticated but wanted to ‘dip a toe’ in the water and explore the possibilities for making various small parts and fittings for the ‘odd-ball’ locomotives and other vehicles that I enjoy creating.” It’s now clear that my choice has met this need very well!
Two small parts that I didn’t show before are the two axles, which are simply tubes through which I could thread a 0.7 mm diameter wire, to form the wheel bearings. I added some flats near the ends of the axle tubes to make them easier to attach below the springs.
3D Printed Axle Tube with Wire Hub Bearing
I attached the front axle assembly to the fore-carriage in a similar way. The fore-carriage itself is pivoted on a metal pin extending down from the hub of the ‘fifth wheel’ on the fixed frame.
Metal Perch Pin for the Swivelling Fore-Carriage
The roof has a simple rectangular plan but I couldn’t decide about curvature. The distant view in Peck’s book: ‘The Great Western at Swindon Works’, assuming it really is this carriage, appears to show a white single arc roof, similar to that on a railway van. The side-on photo, however, on which I based my model shows a black roof, which may have a slight fore and aft curvature. After looking at many more carriage images, I decided to apply a shallow curve across the width, as shown below
This completed the main assembly of the carriage – the wheels turn and the fore-carriage swivels. I was also pleased that the vehicle sat level on its four wheels.
Brunel’s carriage apparently earned the sobriquet “Flying Hearse”, which presumably refers to its black colour.
I felt that overall black would look rather dull on a model so I decided to paint the wheels red and add a few additional touches of colour to window frames and the box seat. The final appearance of my carriage is as shown below:
My model in black with red wheels
It will need a centre pole to attach the horses, a driver, and carriage lamps, to complete the model. In 4 mm scale it is rather small and it’s difficult to see all the details once painted black. I shall have to create a scene where it can stand out! In the meantime, it's travelling on a carriage truck:
My Model in Transit
I think this view illustrates the great increase in size from road vehicles of the 19th century to a contemporary railway carriage. The accommodation in the Posting Carriage must have seemed extremely spacious to those early patrons!
POST SCRIPT: After placing my Britzka model on a carriage truck, I realised it was rather too wide. I have now narrowed the body and shortened he rear axle so that the track is the same as the front axle. I think it is now closer to the dimensions of carriages of the period. Assembly of the small parts was very fiddly and I must improve the design of future models to simplify the assembly task.
Edited by MikeOxon