Bluebottle
This was my next engine and as it was a variant of the well known 'Romulus', I originally called it, 'The Romulant'. However, I ended up calling it 'Bluebottle' as a more popular name for children. The lantern on the front used an LED for its light.
This proved to be a very heavy engine and although it pulled well enough, it might have been worth increasing the boiler pressure to 120psi. Another possible improvement, which I have seen, would be to use Walschaerts valve gear instead of Hackworth.
After running for a few seasons, the cast iron wheels were beginning to show ridges in the treads which were caused by the fact that the rails were much narrower than the wheels. Since it's not a 'real' engine, steel wheels to one's own design might be a better and cheaper option.
One of the extras I included was a well tank in the front linked to another tank as it was on the small side. I also used hydrostatic lubrication.
This is a photo of the original drawing as supplied. Note the valve gear being one that is not usually recommended but easily made although final adjustment is critical. Hackworth.
This is a simplified CAD drawing of the final design.
When I was building this engine, my internet provider gave me a very generous amount of space to upload anything I wanted to. So I began a monthly diary (blog?). There were 28 of these entries and I still have copies. The entries contained much written stuff and photos which could be enlarged by clicking on them. The file is big and zipped or otherwise, when I try to include it on this page, they lose the photos.
Note the twin hydrostatic oilers and the fact the regulator is half open to warm up the cast iron cylinders to get rid of condensation.
Never to look this clean again. Not a 'real' engine but still quite pretty. Later, I lagged those copper steam pipes with three layers of string and I replaced the oversized whistle as well. This side tank is half coal and half water. Two injectors and twin axle pumps are fitted. I also fitted a site glass for the water tank beside the reverser.
Pulling out of the Bristol SMEE station. This was about 2010 I believe.
The engine behind 'Bluebottle' is Jim Lewis in his version of the Kerr Stuart sister to my 'Macrihanish' which we built at the same time.
These photos show the construction of the steel boiler with the firebox being made up in two parts before welding together. The disadvantages of using steel are easily noted. The slightly smaller grate area and fewer fire tubes so less efficient. It looks a very long boiler but this design includes the smoke box.
This shows the poor quality castings, particularly the endcap and out of line steam ways.
The sliding valve block had a tendency at the end of the stroke to stick out of the top a fraction and I was afraid that had it got wedged or worse, come right out, would cause a lot of damage so I extended them and put a cover plate over so that it was not possible.
The pony truck is free to pivot. The suspension is coil spring. Side springing is via a plate on the frame which slots between the two sprung loaded bronze bars. (centre pic) The two large bronze blocks on the top rub against a plate on the frame. Simple but effective. This alone fitted to the 0-4-0 version would be enough to stop the bucking.
The ejector for creating the vacuum for the carriage brakes. Not difficult to make once you've made the two 'D' bits. One 12 degrees and one 24. It easily pulls the 12 " required to work the carriages. Brake lever is simple slide type which closes and opens to atmosphere.
It's not really possible to make accurate springing because the weight of the finished engine is not known. However, my estimate was reasonable although on the soft side but this was good for uneven tracks.
Some of the photos from the original web blog. The hydrostatic oilers are filled with glycerine which enables the oil from the pressurised oil tank to be clearly visible drop by drop. The advantage of these over mechanical oilers is that the quantity is controllable as well as being visible and thus avoids spraying passengers!
