Relander Modelworks

Introduction

After assembling a test girder to see if it was possible to fabricate a laced girder in N scale from scratch, I decided to keep going with the original plan. Now I will be assembling the six end posts, the diagonal girders at the end of each truss. I could have used the test girder, but I would have had to cut it apart to paint the inside surfaces. After the end posts are assembled, I will be building the diagonals and chords needed to assemble the trusses.

Based on what I can tell from photographs, the end posts used on the center girder added in 1929 are the same as the end posts used on the original outer girders built in 1899. It's possible that they were reused from another bridge of the same time period. The biggest difference in the girder lacing is between the diagonals and the bottom chords on the outer and center trusses. The diagonals on the outer trusses are double laced and the bottom chords use zig-zag lacing. All of the laced girders on the center truss use normal single lacing.

Lacing

Laced faces for the end posts are fabricated over a QCAD drawing using 0.010" styrene strips and sheet from Evergreen Scale Models. Side channel flanges are cut from 0.030" x 0.010" styrene strip. They are cut longer than necessary and trimmed to final length after assembly. The outer edges of the flanges are spaces two scale feet apart.

Scale two-foot square stay plates are cut from 0.010" scrap styrene sheet. The stay plates keep the flanges separated at a fixed distance while the lacing is added. The lacing bars are 0.020" x 0.010" styrene strip applied in an alternating pattern across the flanges.

The laced faces are flipped over, and the rough ends of the lacing are trimmed off with an X-Acto knife. The front is lightly sanded with fine grit sandpaper to remove and rough edges and any other blemishes as shown in Figure 2. The surfaces need to be smooth since rivet decals will be added later. The flanges would normally be part of the side channels, but they need to be separate to allow the insides of the girders to be painted.

Assembly

Side channel flanges, side panel webs, and back face plates are cut to length from 0.010" styrene strip as shown in Figure 3. The 0.030" x 0.010" strips for the flanges are available commercially, but the others need to be stripped from 0.010" styrene sheet using an X-Acto knife and a straight edge. The channel webs are about 15 scale inches wide, and the back plates are 24 scale inches wide. The channel flanges and the back plates are both cut longer than necessary since they are trimmed to their final length after assembly.

Attached flanges to one side of the side channels as shown in the left two pile in Figure 4. From left to right are the left-side channels, the right-side channels, the laced front faces, and the back face plates. The side channels only have a flange on the side where the back face attaches since the other flange is built into the laced front face.

The side channel flanges are attached to the edge of the back face plates as shown in Figure 5. Since the back face plates are cut longer than necessary, they are trimmed at an angle to match the ends of the side channel flanges. The backs of the side channels should be spaced 0.090" apart. They should also be perpendicular to the back face plates and parallel to each other.

Several thin layers of DecoArt Americana Burnt Sienna acrylic flat base coat are applied to the undersides of the lacing and the insides of end posts as shown in Figure 6. The insides of the end posts are painted at this stage of the construction since it is very difficult the paint the insides after they have been assembled. The outsides are not painted since they will be having Archer Fine Transfers N Scale Resin Rivet decals applied to them later.

Conclusion

After the base coat on the inside surfaces of all the end posts had dried, I attached the laced faces to the side channel flanges, being careful that the edges of the side channel webbing lined up with the edges of their flanges on the laced faces. I also made sure that everything was square. Now that the end posts are assembled, I can build up the rest of the laced girders and assemble the trusses.