Part 6: http://www.trainsanddioramas.com/n-scale-bascule-lift-bridge-assembly/
Finally! This is the most exciting part of the whole project where you start to get a feeling that you are near completion. However, this section is also the trickiest and requires utmost attention to measurements and alignment.
I used Code 80 Atlas flex track for the bridge. First I cut a 195 mm (7.68”) section from a standard 30” section. You might ask, why 195 mm (7.68”) instead of 190 mm (7.48”), the length of the leaf? The answer is, to ensure better alignment with the fixed track on the layout. Since the alignment depends on a number of factors, if you keep the track length exactly 7.48” when you install it, it might create a large gap between the fixed rails on the ground at the far end of the bridge. You cannot extend the fixed rail beyond the boundary of the leaf because that will not allow your bridge leaf to move up or down, so it is advisable to leave a little extra length (5mm/one tie width is good enough).
The first step of rail installation is to make solid electrical connections to the leaf track section. To ensure long lasting electrical connections, I used copper strips as strengtheners/retainers. I wrapped wire around the strips and folded them, and then I inserted the copper strips between the rails and the plastic ties to make a secure connection. I then soldered them to ensure the connections remain solid. I conducted a quick test using a 9V battery and my favorite little engine, a Kato NW2 (Photo 50).
The next step was to paint the track. I took a “size 00” brush and a tube of acrylic burnt umber paint, and applied the paint directly to both sides of the rail to give it that rusty, dirty look, as shown in Photo 51. The 2.5” Atlas sectional track in the photo will be the fixed track on the tower base.
Photo 52 and 53 show the next steps in terms of making the railroad tie bases, the long supports along the length of the leaf on which the ties sit. I used thin cardboard to do this; C80 rails are pretty strong themselves. On top of the strong wood structure they don’t really need added support underneath. However, if you are using Code 55, it is necessary to put thin wood or 2 mm (0.078”) thick styrene underneath for support. Once the rail assembly, as shown in Photo 53, was painted I installed it on the leaf along the centerline of the bridge. Again, be sure to use caution to keep proper alignment of the rail. This is critical when using flex track, as it tends to bend quite easily.
Now it is time to link the leaf to the tower permanently. Once the basic detailing of the leaf is done and your track has been installed, test it (Photo 54). In Photos 55 and 56, you see how I linked the leaf with the tower simply by using paper pins and electric wire insulators. In Photo 57, you see how the 2.5” Atlas sectional track is fixed and aligned to the track on the leaf.
An important factor in alignment is the rotational alignment. That is, once the tracks are fixed in proper alignment in the closed position, you must be able to rotate the leaf upward. For this you have to ensure that the pivot on the tower is slightly above the fixed rivet (paper pin) on the leaf.
Once the tracks were aligned and fastened using glue, the first thing I did was test the alignment with a piece of rolling stock and a loco to see if everything works properly. Do this when the glue is not fully set. If there is any fine- tuning that needs to be done, it is best to do that at this stage. The aligning might require some fine-tuning of the track as well. You might have to use emery paper or a small file to file the track.
Photo 59 shows the overall assembly at this stage. Notice the rivets on the retaining plates.
In the next post, I will show you how I completed the project by adding a few important details and talk a little bit about the installation. If you subscribe via email, you’ll receive the future posts directly in yoru inbox which I’m sure is more convenient to follow along.