N Scale Workshop

Introduction

After completing the steel towers that will eventually go on the ends of the main span, I will now be constructing and installing the large cross braces that go across the end posts on the outer two trusses. I will also be applying rivet decals and applying several thin layers of base coat to the back plates on the end posts. This will allow the steel towers to be installed without getting in the way.

The end braces on the prototype can be seen in Figure 1 behind the steel tower. They connect the ends of the end posts on the outer trusses and sit above the middle of the end post on the center truss. This may have dictated the amount that the third truss had to be lowered. They have an interesting design that is typical of steel deck truss bridges. One of the braces is narrower than the other one and the wider brace has a slot in the middle. The narrower one would have been installed first and then the wider one would have been built around it.

Fabrication

Two sets of braces are fabricated from strips of 0.030" x 0.010" styrene from Evergreen Scale Models laid out over a CAD drawing created in QCAD. Stay plates cut from scraps of 0.010" styrene sheet keep the sides separated at a fixed distance. The sides should be parallel to each other, and the narrow brace should slip through the slot in the middle of the larger brace.

Similar to the lateral struts, the end brace lacing is fabricated from 0.020" x 0.010" strips of styrene using the CAD drawing as a guide. The lacing is cut longer than necessary and trimmed to length. Strips of 0.030" x 010" styrene are attached to the backs of the braces as shown in Figure 3. The long strips act as one side of the angle irons that sandwich the lacing.

Assembly

The other edges of the angle irons are cut from strips of 0.020" x 0.010" styrene and fastened to the edge of the front and back of both sides of each brace. The smaller brace is inserted into the slot in the middle of the larger brace and connector plates cut from scraps of 0.010" styrene sheet are fastened to both sides of each end as shown in Figure 4.

Several thin layers of DecoArt Burn Sienna acrylic base coat are applied to the back surfaces of the braces as shown in Figure 5 before installing them across the ends of the outer trusses. The backs of the braces are painted first since they will lay on the back plate of the center truss. The end posts of the outer trusses will also get in the way of painting after they are installed.

Installation

Strips of Archer Fine Transfers N Scale Resin Rivet decals are applied to each edge of the back plate on the center truss. After the decals have set, several thin layers of base coat are applied to the back plate. The center back plate needs to be decaled and painted first since the end braces will lay on top after they are installed.

The assembled end braces are installed between the end posts of the outer trusses. The edges of the connector plates are fastened to the back plates and opposing side channel flange on the corners of the end posts. The surface of the connector plates on the end braces should be flush with the mating surfaces on the end posts. The unbraced ends of the lower chords on the outer trusses should be parallel to each other and in line with the other lower chords.

Conclusion

I applied strips of Archer rivet decals to the edges of the remaining back plates and on the connector plates of the narrow end braces. After the decals were set, I gave everything several thin layers of base coat as shown in Figure 8 and touched up any areas damaged during handling. Then I repeated the process for the end braces on the other end of the bridge.

Now that the end braces are installed, I can install the steel towers and complete the detailing on the ends of the main span. The final lateral struts and lateral cross braces will be installed along with gusset spacers and bridge shoes. The remaining stringers will be added to connect the floor beams to the tops of the towers. The tops of the stringers are six feet above the tops of the towers so there will also be some additional supports and bracing that will be added. After that, I can start on building the support piers, deck, walkways, hand railings, hand laid track, and ballast.