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/
Part 3: http://www.trainsanddioramas.com/bascule-lift-bridge-the-concept-of-scrap-building/
Part 4: http://www.trainsanddioramas.com/scratch-building-a-bascule-lift-bridge-the-rocking-truss/
Just to recap, so far I’ve shown how I’ve completed the base structure of the leaf and the rocking structure. Photo 15 below shows all that’s done so far, and the links above will tell you how I’ve reached till this point.
The Tower
This part of the build is important from a structural standpoint since all of the moving components witll be attached to this structure. As mentioned before, the base of the tower is 60mm X 40mm X 10mm (2.36” X 1.57” X 0.4”). Looking at the drawing you can see that the vertical side of the tower needs to be 70mm (2.75”) in height. My first job was to cut two strips of 80mm (3.15”) in length and fasten them in place. 10 mm (0.4”) of these beams are glued to the base and secured with pins as shown in Photo 16. I also added a 40 mm (1.57”) stabilizing cross support beam in between these two vertical beams towards the top (10 mm/0.4” below the zenith). This makes the basic structure of the tower. One important note is that since the tower will act as the rigid frame of the structure and the frame of movement of the moving parts, it is important to test the assembly in each major step. Photo 17 shows the testing of clearance of the tower and the rocking truss.
In Photo 18, you can see the diagonal end posts being installed. Note that it is extended beyond the top face of the base to the entire side face of the block to ensure the stability of the structure.
Notice that the structure has started taking solid shape now and all basic references are in place. As you see, the actual construction looks slightly different from what you see in the drawings. These deviations are to ensure better strength, rigidity and reliability of the structure, parameters that unfolded only during the building phase. Since we are dealing with wood at 1/160 scale, it is permitted to make slight deviations from your drawings to ensure a better long lasting bridge. However, make sure that the basic and critical dimensions match with your initial design; or you might end up having alignment issues in the future.
Now, with the basic structural components in place, I will demonstrate (through photos) an accelerated process for completing the rest of the details without going back to the drawing for every step. If you have maintained your dimensions accurately to this point, the rest of the sides will fall into place automatically. You will see this in depth as you complete the tower as shown in the step-by-step photos 19 – 39.
Completing the Leaf (Deck)
If you’ve following along, you’d know that I took a little deviation from completing the leaf and started working on the more critical structures. The reason being, they are that critical. The basic structure of the leaf was done previously as you have seen in Part 3. I wanted to make sure the complicated components were complete before returning to the leaf. This ensured that I could mock up the overall project as I progressed, and cross-reference it with the drawing from time to time. The joints in the leaf also got time to get seasoned and securely held by the glue and the pins.
I used the same accelerated method that I used for the tower to measure, cut and affix the diagonal support beams of the leaf. As long as the square joints are proper, this is not a problem. The diagonal supports on the sides were easy, however, the ones at the top and bottom had to be individually beveled to achieve a snug fit. Photo 40 gives you a good idea of how this looks upon completion.
Here are the some other photos of the completed components so far.
Now that the components are ready, it’s time to star assemblying. If you subscribe to the blog via email, the articles will be delivered directly to your mailbox.