Soldering your rail joints is good for electrical conductivity; but can lead to serious problems if the temperature of your railroad room is not relatively stable. If your RR room temperatures has extremes as mine ( in an attic space) does; your rail will expand and shrink with temperature. If all your solder joints are soldered you can have electrical gaps close up in the summer and solder joints break in the winter.
Good practice for DC, and almost necessary for DCC, is to have a separate electrical feed for each length of rail. rail alignment at the rail joint is, or at least should be controlled by the rail joiner. Just as all track is not created equal, neither are all rail joiners equally capable. the rail joiner has at least two functions, the primary function is to align two sections of rail together accurately, and the secondary is to provide an electrical path between the rails. Should one have enough rail feeds (I seldom do), the secondary function is not critical.
There are many brands of rail joiners, and they are available to match various sizes of rail (measured in code). The rail joiners have two basic designs though. All have a flat base that the bottom of the rail sets on. The Atlas design has curved sides that curl back together to pinch the rail between them. This is likely done for electrical conductivity, and is not necessary if we wire our rails properly. the biggest issue with this is aesthetic , the curled sides don't look anything like a fish plate on the prototype. Other rail joiners have a more aesthetically pleasing shape having a flat bottom, and the rail joiner is bent at angles to follow the top of the rail's base and side. The Peco rail joiners are made like this, and some of them even have bumps pressed into the side that sugest the bolts on a fish plate.
I mentioned rail height earlier. rail height is referred to as code. The most common rail used in HO has been Code 100. code 100 rail is 100 thousandths of an inch tall. That scales out as some pretty big rail. There is some rail in the US that is that heavy. Real railroad rail is measured by weight per foot. I'm pulling numbers out my *** right now, but I'm thinking code 100 represents something like 150 lbs rail, in the US there is some rail that heavy, mainly in the NE corridor , but most rail in the states is considerably smaller. Because of this code 83 rail is getting more popular. Code 83 rail is 83 thousandths tall, and is a close representative for 100 lbs rail, which is closer to the common size rail for modern American mainline track.
The next smaller rail size is code 70 , 70 thousandths tall. it is a close representation for 70 lb rail which would be found in modern times on branch lines, short lines, sidings and yards; and historically on the main lines of railways back when the equipment was lighter. I use code 70 on my narrow gauge, it is probably too heavy, but AI get better reliability with it than with the smaller rail sizes. After code 70 comes code 55 On My current railroad I have some code 55 on sidings where the main is done in code 70. When hand laying track with code 55, one must be very careful to have spikes with tiny heads, or the spike heads will interfere with the flange ways. I had some serious problems with that in my old Harlow. The smallest rail I know of is code 40, code 40 is tiny. I had some code 40 on a railroad I had when I was in High school in Atlanta, back in the dark ages. I had some HOn3 with code 40, and I had a standard gauge yard with stub switches built with code 40 rail . Every fourth tie was made out of printed circuit board, with a cut across the center so the rails would not short out. The code 40 rail was soldered to the pcb ties, as the rails were so small there was no room for spikes and flanges. My friend Peter Sander, visiting from Ohio got bored one day, and put weeds in the yard. it was awesome, the track disappeared. when you switched that yard the locomotive and cars would be wandering through the weeds.
A word about rail profile. the standardization of rail from manufacturer to manufacturer does not extend past the code (ie rail height in thousandths ). so if you had two pieces of code 100 rail from different manufacturers the height would be the same, but the rail head might be wider on one brand than the other. likewise the base of one rail wight be wider on one , and the center of the rail might have differ thickness. because of that, a rail joiner wight be a perfect fit for one section of code 100 trail, and a sloppy fit on another. in that case, soldering the rail joint would be a good idea. So getting rail joiners made by the manufacturer of your track wold make sense in all cases but Atlas.
when I have track down I like to run my finger across the rail joints to feel for variances in track alignment. I run into that all the time at the train club where he have a lot of Atlas rail joiners. I will use them at home, if I'm out of any other brand, and desperate, but otherwise you couldn't run fast enough to give be a bag full of them.
I will try to come back and back up this tome with some photographs when I have time to take some, and edit them.
Bill Nelson
