This is an instructable for building a Girder Railroad Bridge (largely of my own design) in N-Scale or (1:160). The 3D model files can be found on Thingiverse. This bridge is actually intended to be part of an ABT style of Bascule Draw Bridge but I decided to release it as a normal bridge first.
Step 1: Print the Parts
The parts for this model need a with a 250 micron nozzle. You might be able to get away with using a more standard 400 micron nozzle if you dial back the extrusion width but quality will suffer.
Different lengths of bridges can be created with this kit though I only provide two, one of 96 feet in five sections and one of 115 feet in six sections. The latter is the largest that my printers can handle (with a reasonably large bed) and the five section should fit on a lot of smaller printers.
There are two directories that contain the parts for the two sizes of bridges that I mention above though they only include the parts that are length specific. There are three stays or strings that are in the root directory. Speaking of the root directory...you will find the source Sketchup and STL files for each section sized piece of the bridge.
The bridge that I will show being assembled here is actually intended to serve as a draw bridge so one end of the construction will differ from a stand alone bridge!
Here are the parts that you will need...please note them in the above photo!
- 1 x bottom
- 2 x sides
- 1 x top
- 2 x # of sections top stringers
- 2 x end braces
- 2 x walkway
- 1 x track bed
When you load the parts into your slicer you will have to reduce them to print as I model in full scale! Factor for 1:160 is .625.
Step 2: Assemble the Stringers
The stringers should neatly fit into the slots on the underside of the top piece. The inner should fit neatly through the outer.
Step 3: Insert the Sides
Insert the two sides into the bottom. This will be a tight fit so make sure everything is lined up before you press the parts together.
Step 4: Attach the Top
Attach the top ensuring the edges are flush...check with a loupe!
Step 5: Insert the Track Bed
Step 6: Install the Track Bed
Install the track bed making sure everything is flush. On a normal bridge the walkway would be installed at tis point.
Step 7: Putty, Sandpaper, Small File to Cleanup Model
Clean up the assembled model! Some putty will close gaps at the top with some fine sanding to finish. Use a file for any printed parts that my be rough.
Step 8: Paint and Weather
In the case above we did a quick paint job of a base color.