N scale refers to a model railroading scale where every 1-inch in scaled length is equal to 148 actual inches. The scale, one of the smallest in common usage, is widely embraced by model railroaders with little space in which to build their layouts. When laying track, you want the rails to be as level as possible between track pieces, with a solid connection between rails. At smaller scales, even tiny changes in level can translate into large visible bouncing, leading to noisy locomotives and increased chances of derailment. A bad connection between rails also interferes with the electrical current moving through the track, causing uneven locomotive operation. Soldering the track pieces together reduces the chances of laying unlevel track, leading to a much smoother ride for your trains.
Push thumbtacks through the spike holes of your track to hold the track securely in place during the soldering process. Nail the tacks in place with a tack hammer to ensure the placed track is level on the board throughout the track length.
Dab a small amount of rosin flux paste on the end of a toothpick. Flux paste transfers heat evenly and helps the solder flow. Spread the paste along the joints between tracks on the outside of the rails in the small rail groove.
Take a soldering iron and heat the two rails on either side of the joint as well as the small rail joiner piece that the rail ends slide into to join the pieces together. Apply the heat to the outside of the rails.
Touch the tip of the solder wire to both the rail groove and tip of the soldering iron along the joint area, while heating the pieces. The solder will turn into a liquid and flow through the joint area, aided by the flux paste within a few seconds. Cover the joint completely with the solder and then remove the wire. Allow the solder to cool and harden for about 10 to 15 minutes.
Dip a cotton swab into rubbing alcohol. Wipe the hardened joint with the swab to remove any remaining flux paste.
If you make a mistake and apply too much solder, reheat the metal to spread it further.