A more in-depth guide on how to solder can be found at makerspaces.com, here we'll go over the essentials.

What is Soldering?
Soldering is the process of joining two or more metal parts together using liquid (molten) metal as a sort of electrically conductive glue. The solder is a metal wire that has a low metal point. Just dripping some liquid metal on our parts won't cut it though. We need to heat up the metal parts so that the solder will "wet" or stick to the metal. If we just drip some liquid metal on, it will simply ball up and not stick to the metal, or will just create a bad connection. When the solder "wets" to the metal, it sticks onto it just like water. If the solder is "wetting" it acts like the parts are hydrophobic and won't stick at all. By creating a good solder joint, we make sure that the parts are physically bonded together and have good electrical conductivity once the solder cools and solidifies.

Soldering Tools and Materials
In order to solder you'll need a few things: Solder wire, a soldering iron to heat the solder and the joint, a wet sponge to clean the soldering iron, and flux to clean the metal surfaces to be joined by removing any oxides or impurities on the surface that might cause a bad connection. In the tutorial videos, you'll see me using what's called a "third hand" which has clamps to hold onto what you're trying to solder. This is only to help you see what's happening in the video and isn't necessary for these projects, however it can be helpful for more complex jobs or if you have dexterity limitations. The blue mat is a heat resistant silicone mat that is useful for any soldering/cutting/dissassembly DIY projects, but is also not necessary for these projects. Any heat resistant surface that you don't mind getting messy will do, but if you think you'll be doing more of these in the future it's a good investment! You'll also need personal protection equipment such as safety glasses and if you're in a room with poor ventialtion it would be advisable to get an exhaust fan.

How to Solder

Step 1: Prepare your work space
Clear the area of any unneccessary clutter, anything that could be knocked over or caught on a cable, or anything that could be damaged by the heat of the soldering iron or an erroneous blob of solder. Set up your soldering iron by assembling it per the instructions, wet the sponge with some water, make sure the tip of the soldering iron is clean, and when you're ready, turn on the soldering iron. If it has two settings, use the lower one for these projects. The higher setting is for more heavy duty jobs, and will actually make it harder for you because it can melt things you don't want to melt much faster, such as the insulation of the wire, or nearby plastic connectors.

Step 2: Prepare your Solder Joint
Use tweezers, some weights, pliers, or a "third hand" to hold down the parts you want to solder so they won't move around when you touch the soldering iron tip to them. Make sure that whatever you use won't be melted (temporarily hot gluing them is not a good idea since the glue will heat up and melt again, just in case that thought crossed your mind). Once your parts are set up, apply a small ammount of flux to the metal parts you want to solder. This will clean the surfaces during the soldering step.

Step 3: Heat the Joint
Start off by "tinning the tip" by applying a small amount of solder directly to the tip of the soldering iron. This increases the contact area of the soldering iron and helps you heat up the metal much faster. If you find it's taking forever for the soldering iron to heat up the metal enough for it to accept solder, it may be because the iron doesn't have enough contact area with the part you're trying to solder. When the tinned tip of the soldering iron touches the joint you should hear the flux sizzle away as it gets hot and does its job of preparing the metal surfaces.

Step 4: Apply Solder
Now that the tip is in contact with and heating the metal you want to solder, the metal will start "sucking up" the liquid solder as it "wets" the metal. Then, start applying additional solder either directly to the joint, or by adding to the pool already on the tip and allowing the metal to suck it up. Do not try to force the metal to accept the solder, if it looks like the solder is blobbing on top of the metal instead of wetting into it, try using more flux, or cleaning the surfaces, or roughing up the surface with some sand paper and trying again. You want to use the least ammount of solder possible to get a solid joint, and you also want to ensure that the parts are still making metal to metal contact so that the electricity flows through the metal parts themselves, not through the solder. Solder is electrically conductive, but not that well, so you don't want to have it inbetween your connections.

Step 5: Finish the Joint
Once the joint is complete, clean off any excess solder or contamination from the soldering iron tip by wiping it off on the wet sponge and returning it to the soldering iron stand. Wait for your soldering joint to cool before touching it, as it will remain hot for a while afterwards. Over time your tip will erode and tarnish, and will eventually need to be sanded clean or replaced with a new tip. Keeping your tools and equipment clean and well maintained will make them last longer and work better. When you're done soldering, turn off the soldering iron and allow it to cool completely before unplugging, cleaning, dissassembling, and putting away the iron.