If you join the two-piece of rail with metal rail joiners, then solder the join; the solder will flow much more smoothly. This assumes you're using nickel silver or brass rail of course! Make sure
that the soldering iron heats all three metal parts (i.e. both rail ends and the rail joiner) to the same temp before applying the solder, and it should be drawn into the space inside the rail joiner
without any trouble.
Note that solder is not a very good gap filler, so if you've got gaps larger than about 0.5mm or so, you'll waste your time trying to fill them with solder without having a bulging great lump of
solder in the way of the wheel flanges.
Also note that you should still have non-soldered gaps every meter of so to prevent the solder joins fracturing due to expansion and contraction. Ideally, straight track should have NO directly
soldered rail joints, but you should use bridging wires to leave the rail ends free to move. Curved track will usually need to have soldered joins unless you're particularly skilled at spiking rail
on curves.
...
I am one of the proponents that do not believe in soldered joiners. Joiners should be left free to move and expand as nature dictates.
Joiners are a mechanical way to join two pieces of rail, and should be just that. They should not be electric current carriers. No matter how good the contact is, it will eventually fail due to
oxidation. I believe that the "bus" method (i.e. a wire line that follows each section or block around the layout) is the only reliable method to power a layout, but that is my own opinion. There are
a few different approaches to dispense power to all sections on a layout.
A lot of people will say that it is a waste of time to solder the wire under the layout to the track, but think of the fewer headaches you will have with electric problems.
I would like to give two examples:
1) N-trak and modules in general (no explanation here).
2) At the club I am a member of, the layout was built in the early 50's. The HO mainline is still the original one. It is code 100-brass and has 3 major blocks. Rail is laid down and spiked on True
Scale patterns (cannot think of the name). I do not know how long the main line is but we had a train with 98 cars (we run mostly modern cars) and 10 engines pulling and it occupied just less of a
half of the main line. Each rail is joined but not soldered.
Back then they used a method used in O gauge layouts. A piece of wire was soldered near the end of each rail, connecting electrically the two rails. Talking to the old members, they hardly had any
problems as far as power flow is concerned (shorts yes). The only problems of power flow were due to failure of the solder joints. Even now, after 40+ years we find the need to re-join some of the
wire with new solder (after a good cleanup), although most of them are still the original solder joints.
Performance is very reliable, and that is what counts in the end.
1) Use a GOOD soldering iron
1A) make sure the tip of the iron is CLEAN and TINNED (When the iron is hot, wipe it quickly across a WET sponge. Coat it with solder and wipe again. When the tip is shiny, it is properly tinned)
2) MAKE SURE it is PLENTY HOT!!!
3) Use soldering flux on the rails/rail joiner (VERY important; without flux, the solder will not flow)
4) If necessary, use heat sinks (available at most electronic parts outlets, ie Radio Shack) on either side of the soldering (attatch to rail)
5) Touch the iron to the rail ONLY! A few seconds at the most, and the solder will FLOW into the joint. Remove the iron immediately
The ties generally won't melt unless you touch the iron directly onto them...They may soften a bit if the iron heats them up...use heat sinks... this will help! Otherwise, play around with pieces of
scrap rail until you've gotten good at soldering quick, smooth joints. Again, Points 1 and 2 cannot be understated...!
Lt. Jim
New York City