One of the most uncommon talents among do it yourselfers is the ability to solder cleanly and effectively. Without basic instruction, there’s almost no possible way to solder even the easiest application successfully, especially in the starter alternator world, where skilled soldering can be a necessity.
The cool thing is: it’s actually pretty easy, and requires very little experience, once you understand a few basic concepts, and get a basic idea of the tools you need and the procedures you need to follow.
There are two main concepts you need to be aware of when soldering:
1.) Proper cleaning
2.) Capillary action
Proper cleaning and preparation is scarcely a little more than just good common sense and a wire tooth brush. Always clean both parts that are going to be soldered equally. Even new parts must be cleaned with a clean wire brush. Then coated with flux paste and heated just before performing any solder operation.
After, and ONLY after both parts have been meticulously cleaned and fluxed can a successful solder joint be achieved. Any soldering should occur immediately after the flux has cooled, because even a few hours can allow re-oxidation to occur. Some people get the bright idea of glass beading to clean, but there are too many impurities in the sand.
Capillary action in short is the uncanny ability of solder to flow towards the heat. Plumbers use this to their advantage all the time. When you solder two pieces of pipe together you never heat the pipe, you always heat the joint. Gravity in this situation makes no difference whatsoever, as soon as the solder melts, it can travel up hill and around the corner, then suck itself in a circle, just to get to the heat.
Technique. So you could call solder a true heat seeker or a heat magnet. This is what needs to be kept in mind in the auto electric starter alternator soldering. When dealing with smaller parts where an open flame is not an option, it is important to equally contact both parts with the soldering gun. Heating components occurs through heat transfer. Therefore both parts need to be contacted equally in terms of surface area.
So if you’re working on a solder joint and 80% of the gun tip is touching one half of the component, and the other 20% of the gun tip is touching the other component, the joint is destined to be defective or “cold” because all the solder will flow towards the heat. The successful solder joint will start out by a 50/50 contact area with the gun tip.
After the gun has been pre heated, touch both components as equally as possible. Then you have to maintain this contact for several minutes. Hold the solder 1/4 to 1/8 inch away from the gun tip. Wait for it to liquefy, then spread the solder around quickly using the tip of the gun to stay ahead of the melted solder like the carrot ahead of the mule.
Be sure to solder all the lines, so centrifugal force can’t work on the joint at high RPM. Remember: clean thoroughly, even new parts with a wire toothbrush. Heat both components equally, then, move the gun ahead of the molten solder like the carrot ahead of the mule. Try not to ever let the molten solder touch the actual gun tip.
Care. Many experienced technicians recommend “tinning” the gun tip with the roll of solder just before and after the job. This is a simple process of heating the gun and melting a little solder to the tip. Then reheat the gun and fling any extra off, while it’s still molten. This sounds like an oxymoron, but it’s not. You will notice a light coat of solder retained on the tip which signifies cleanliness and prevents corrosion.