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24 December 2018
In this final part of the design for a 3D printed model railway building I've added additional features such as the door, windows and roof as well as adding a smoke generator.
These were all designed in TinkerCAD. These are designed in TinkerCAD and then exported for 3D printing.
The smoke generator is fitted into the top of the chimney. It is possible to buy smoke generators specifically for buildings, but unfortunately I was not able to find one from any UK suppliers. I therefore used one designed for a OO model railway steam locomotive. This worked, but the amount of smoke is a bit much for a building chimney. You can see the smoke effect in the short video below.
All the files are now available to download:
Here are a list of the changes that I made since the original and the reasons for the changes:
Initially I'd separated the main part of the building into two pieces. There was two reasons for this, one was because it made it easier to open up the building to access inside; the other is because of the overhang at the top of the building which means that a lot of additional support is needed during the 3D printing process (the way that the additive 3D printing works means that you cannot create significant overhand without adding temporary support).
The main problem this created is that the two parts didn't fit together quite as well as I hoped. The parts went together, but left a gap between the two parts of the building, especially at the corners. This was partly due to warping of the material at the corners (the corners curling up on the lower layers). I did have the heated bed set to a fairly high temperature (which appears to work better with some PLA and when printing smaller models). The reason I had the bed temperature quite high is that some other PLA I used needed a higher temperature to stick to the print bed, through trial and error I've now established that the FiloAlfa PLA actually sticks to the bed quite well at much lower temperatures which reduces the warping. So it maybe that is not be such a big problem with future prints, but joints like that are often visible in some way.
With printing the main part of the building as a single object then the print did use a lot of additional scaffold (temporary support) which needed to be removed afterwards, but other than using additional printer filament, which is then discarded, that is not a major issue.
Printing as a single object did work better for this, but this is a small building and is almost at the limits for my 3D printer. In future designs it's likely that I will need to create the building from multiple parts.
On my earlier version the fireplace had been a separate part. This is partly because it was added as an afterthough. In the updated version I have included the fireplace and chimney into the main part of the building.
I also added a smoke generator, to do this I included a hole in the top of the chimney where the smoke generator could be installed and then a longer hole all the way through the rest of the chimney so that I could run the wires through that. The hole within the 3d printer is not very accurate (at least on my printer), so I had to go through it with a long drill, but it did at least provide the guide for the drill rather than risk breaking the model.
The smoke generator that I was able to buy is really designed for a HO/OO model train which fitted into the hole. As the generator is designed for a train it gives out steam in a puffing fashion rather than a continuous stream of smoke as you may expect in a fire in a building. It is possible to buy steam generators that are designed for buildings which would be more realistic, but I am unable to find a supplier that sells them from stock. I hope to order a more realistic smoke generator in future, but for now it does provide a smoke effect.
The roof from part 1 is printed as a single piece. The roof is quite thin but needs a lot of scaffold to be removed and once that is removed it is a bit flimsy. In the new version I updated to add wooden roof trusses which provide additional strength and realism. I also made the roof wider with an increased pitch on the inside rather than the outside. This reduced the amount of scaffold (as scaffold is only required when there is around 40% to 60% overhang).
I have also added a window frame. This is printed separately using white PLA and fits in from the inside. I have then cut out some 2mm deep perspex sheet (transparent acrylic plastic) to fix to the inside.