Re: Running new Wiring for lights?
1. Solder is not glue. Dropping a blob of solder onto two pieces of metal does not make a connection. Solder somehow links the molecules on the materials being joined.
2. All the metals being joined must be hot enough to flow solder to make a good connection
3. All the metals being joined must be clean. If using new/old stock switches, you will have to scrape the oxidation off first. Cut wire insulation back to expose clean metal, or else scrape old wires with a pocket knife so they are shiny.
4. The popular Weller-type guns can make about 3 connections before the connection between the gun's 2 tubes and the tip loop becomes bad. Loosen and gently but firmly re-tighten the nuts or screws that hold the tip in place after every few connections. If you don't, the nuts heat up instead of the tip, because that is where the maximum resistance is.
5. Always have a damp sponge handy as a tip cleaner. In a pinch, an industrial paper towel folded into a small square and moistened will work. I also used to use the legs of my old jeans I was wearing, but after more than a couple of quick swipes they do get uncomfortably hot.
6. Use rosin-core electronic solder for wiring. Never use acid-core plumbing solder.
Make a good mechanical connection first. Twist wires, hook wires through switch terminals and bend the loops shut, or crimp terminals before you start.
Clean the tip of the iron of any crud. You may have to wire-brush or file it, but try to minimize that. Keeping the tip tinned will avoid the need to clean off crud. Heat the iron until it will melt solder. Melt as much as you can onto the tip to cover it, especially a brand new tip. Then wipe it off with a swipe on the sponge. Repeat at least once, more if necessary. The goal is to 'tin' the tip with a thin even coat of shiny solder. This will also float off crud with the excess solder onto the sponge. If there is a dirty area that will not accept solder, clean the tip while it's hot, and get solder on it right away before the metal reacts with the air.
After the tip is clean and has a shiny layer of solder, apply heat to one of the metals in the connection. You can touch the solder feed to the tip to get a heat transfer going to the metal, but then move the solder away. When you think the metal is hot enough, touch the solder to the nearby metal and flow it on. Move the tip to the other metal and make sure that can flow solder, also. If you can hold the tip on the bottom of the connection, and solder melts on the top, it's a good sign the metal is hot enough to flow solder. Move the tip and solder around to be sure that the whole connection can flow solder at the same time. If too much solder starts balling up, swipe the tip on the sponge to clear it. When solder has flowed to the whole connection, remove the heat and immobilize the wires for a minute until they cool.
Someone said "Making good decisions comes from experience, experience comes from bad decisions." I say there are three kinds of people: those who learn from their mistakes, those who learn from the mistakes of others, and those who never learn.