Part 1: http://www.trainsanddioramas.com/ultimate-scrap-building-bascule-bridge-introduction/
Part 2: http://www.trainsanddioramas.com/scratch-building-a-lift-bridge-in-n-scale-design/
As the name suggests, simply build something out of scrap material. Over time I have used various sorts of throwaway stuff and junk to build my models. However, building a structure sitting idly beside the track is one thing, but building a railroad drawbridge, that can take the load of the heaviest of locos while maintaining its alignment and rigidity, is another. This is especially true, if you want to maintain the N scale dimensions closely. My natural choice was wood. I did not go to a hobby shop to buy Balsa or Basswood strips; I decided to use something totally different.
As a whole-hearted miniature aficionado, I often indulge in buying kits and static models of anything that I find to be interesting. I especially like those that come in ‘kit’ form that you have to assemble and paint to make a model. There are plenty of these ‘make yourself’ wooden kits are available now, the one that I really like are the ones by UGears. In Photo 2, you see such a kit to make dollhouse furniture. But I would like to draw your attention towards the remains of the sheets after the components of these models had been punched out, as that is what I used to make an operating bascule bridge.
The ply wood in these kits are rigid, even with just 3 mm thickness they maintain the shape of these model components very well – they don’t bulge or bend very easily – a very important feature to make bridges. Secondly, their thickness is uniform across various kits, and definitely within one kit. I decided to cut thin strips out of these ply and use them to make the bridge!
In Photo 3, you see how I made thin wood strips out of the remains of these kits. All these kits have about 8 to 15 mm of additional space around the 4 edges. I used a ruler and a hobby knife to cut strips of different width, 3 to 5 mm depending on the structural element where it would be used. For an example, the bottom truss, on which the rails would be installed are 5 mm wide to make the structure more robust. I had to keep in mind the texture alignment while cutting these strips; cutting them parallel to the grain alignment would make cutting and trimming these strips easier, and will also ensure better strength of the structure.
Construction of the Bascule Lift Bridge
Now without further ado, let’s get into the construction details of this fascinating structure.
In Photo 4, you can see the starting point of the construction. Towards the left of the ruler, you can spot the wood strips cut and shaped in required lengths. Towards the right of the ruler, you can spot two rectangular wooden blocks that have been glued together. These are a couple of Jenga blocks (another wood puzzle game component) – that is the heavy base of the tower and eventually come to play an important role as we will witness when we get deeper into the construction topics. The dimension of each of the blocks are 60mm X 20mm X 10mm, gluing them together across the 60mm X 10mm sides gives the dimension of the base as you can see in the faces we get – 60mm X 40mm X 10mm. You can also see the basic structure of the bottom truss of the leaf has been glued together in this photo as well. The dimensions are 190mm X 40mm; with cross support beams distributed equally throughout the length and perpendicular to the long sides, and an additional support at both the ends 10 mm inward from the end support beams. You will not find these additional supports in the Google SketchUp plan, as these are improvisations, I made during the building process.
Base Structure of the Leaf
Photos 5 & 6 show the next phase of building, the base structure of the top truss of the leaf and the side beams, and the installation of the side beams. Notice that, though I used top-notch glue to affix the structure, the base structure also has reinforcements in terms of steel straight paper pins (straight pins), another vital item used throughout the construction. I drilled tiny holes in the links and used these pins to secure them in position. I then cut the pin using a strong wire cutter (wear eye protection), and use super-glue to make sure that the whole assembly is properly in place and is solid.
In photos 7 & 8 you see the base structure of the leaf has been prepared, all vertical and horizontal square beams are secured in place, and the diagonal end posts are installed. Looking carefully, you can see how the base is secured using steel paper pins.
Note that throughout the process I took frequent reference measurements from the SketchUp drawing for each dimension. I have used the ‘dimensions’ tool in Google SketchUp extensively whenever building any specific component. You can turn and twist the 3D model depending on which part you are building and use the dimension tool to give you the exact dimensions of every component that you are focusing on.
Make sure to subscribe to the blog so that you can receive the alert for the next installment of the series where I’ll show how I handle the more complex, moving parts of this unique structure.