October 16

How To Solder Wires


There is going to come a time when every RC Rookie, especiallySoldering Bullet connector if going down the Electric Power route, will need to put a new connector on a Battery, an ESC or a Motor so this post is aimed at giving all the information you will need to become proficient in the basics of how to solder wires.

This guide focuses on soldering for the beginner and explains how to solder a variety of plug, sockets and wires using a standard soldering iron and the essential accassories. Soldering can seem daunting at first but if you give it a try you will see that it’s quite simple to do.

  Soldering a Bullet Connector

Soldering is the process of joining pieces of metal together. Soldering occurs at relatively low temperatures  as compared to brazing and welding, which are processes where the metals are actually melted and fused together at higher temperatures. In soldering a filler material called solder becomes liquid, coats the pieces it is brought into contact with, and is then allowed to cool. The two materials are joined as the solder cools and hardens.

Soldering creates an electrically conductive strong bond between components and can be separated or desoldered if you should ever want to disconnect two items previously joined together. It’s great for joining electrical components and wires together. Almost every joint and component assembly in your Radio Control and associated equipment involves soldering.

What You Will Need

Having the right tools for the job effects the quality of the work being done. You will need solder and a heat source to melt it. The following are the basic items you will need.

1. Soldering iron
Although not the only way to solder, most people opt for using a soldering iron. This is a great heat source that heats up and cools down reasonably quickly and can maintain a pretty constant temperature. A medium wattage iron (around 40 to 60 Watt) is what I use for the gauge of wires most commonly associated with model plane power systems. With careful application this type of iron can be used for most of the situations you will encounter. You can buy one on line by clicking this link:- US soldering Iron 60W or from a UK supplier through this link:-  UK Soldering Iron 60W

Typical Soldering Iron & standA Typical Soldering Iron and Stand

2. Solder
There are many kinds of solder available. They come in different thicknesses  but for most modelling applications a reel of 1mm to 1.5mm is most suitable. Most solder is made from a combination of tin and lead – it’s about a 60% tin, 40% lead mix depending on what solder you are using. Recent legislation has ruled that the lead content should be phased out of commercially available solders and it is now easy to find the lead-free versions which are safer to use.

Some solders will contain a small amount of silver. This pushes the melting temperature up a bit, but the silver helps the solder to flow and makes a stronger joint. When buying solder check that the type you are buying is a “rosin flux cored” version. This avoids the necessity of buying a separate rosin flux to encourage the solder to flow between the components being joined.

Flux Cored Solder

A Coil of Rosin Cored Solder

3. Soldering Iron Holder and Cleaning Sponge
It is helpful to have a safe place to put the soldering iron down when not in use. A soldering stand safely holds the iron and gives you a place to clean the tip. Some soldering irons come with their own holders.  The stand isn’t a necessity for learning how to solder, but it certainly helps.

soldering iron standSoldering Iron Stand With Bit Cleaning Sponge

4. Tools to Work with Wires
You will need some basic tools to help you when soldering. These consist of wire cutters, a wire stripper and needle nose pliers. Wire cutters and strippers can be obtained as a single tool.

5. “Third Hands”
You have to hold the soldering iron with one hand and the solder wire in the other, so it really helps to have something else to hold the components you’re actually trying to join. You can use a small vice, alligator clips, clamps, or even some tape to hold things in place if you need to. The third hand is generally a good investment if you are going to be soldering regularly. You can purchase one in the Us from this link:-  US Third Hand  or from a UK supplier here:- UK Third Hand

Third Hand

The “Third Hand”

7. Ventilation
It’s really not a good idea to breathe in the fumes produced during soldering. Any kind of natural ventilation or a small fan set to blow away these fumes will help. Even leaving your work area door open helps.

8. Safety Goggles
Although not essential, safety goggles are a good idea. Little molten bits of solder tend to fly out of the soldering joint when you’re feeding in the solder, and if they were to land in your eye they could cause damamge needing medical attention. Better safe than sorry.

Lets Get Started Learning How to Solder Wires

Once you have all your tools and materials ready, lets pretend that you are a pilot and carry out a pre-flight/solder checklist.

First things first, plug in the Soldering Iron and wait for it to get hot. The tip of the soldering Iron gets quite hot – up to 800 degrees Fahrenheit (427 degrees Celsius), so don’t touch it. I know this seems obvious, but people do seem to burn themselves at some point while soldering. 

If you’re using a new soldering iron you will need to “Tin” the tip. Providing you keep the tip of your iron clean, you should only have to do this the first time. To “Tin” the iron apply a small amount of solder to the hot tip of the iron before you start working.  Once you start using the iron, it will usually have some solder on it already and be ready to go. All it will require is a wipe clean on the wet sponge in your stand so that the solder is bright and shiny.

Now that your iron is hot you are ready to solder. Let us start by doing a very simple joint with two pieces of copper wire and twisting them together. First you need to remove about 1 inch (25mm) of the protective sleeve from each piece of wire. You will notice that the cores are bright and shine because there is no oxidation to dull them. It is important that the cores remain like this so the sooner you can make the joint the better and it helps if you can twist then together with a piece of cloth between your fingers and the wires or use a pair of pliers to make the twist. This ensures that impurities and dirt from your skin do not contaminate the joint area.

Twisting wires togethercool.Twisting Solid Core Wires for Soldering

Having twisted them together as shown here you are ready to solder. Take a short length of solder from your reel and wind it into a coil so that you can hold the coiled bit. You should have a short lenght protruding so that you can touch this to the wire joint. Put the two twisted pieces of wire into the jaws of your “Third Hand”.

Clean the tip of your soldering iron on the sponge and immediately place it under the twist in the wires. Allow a couple of seconds for the heat to permeate the wire then touch the solder to the top of the joint. If it is hot enough, the solder will melt into the twisted joint and coat all of the exposed wire. Remove the solder and the iron tip and wait a few seconds for the wires to cool enough for the solder to reset and become hard.

Don’t be tempted to touch the joint at this point, it will still be too hot to handle. Once it has set you can speed up the cooling process by placing the jaws of your pliers aroung the joint to act as a heat sink. When it is cool enough to handle remove the wires from the jaws of your “Third Hand” and give the wires a good pull to prove that the joint is solid.

soldered twisted wires

Well done, you have made your first soldered joint!

The secret of good soldering is to allow your iron to get as hot as possible, ensure the surfaces to be soldered are completely clean and remove the solder and  heat as soon as the joint is coated.

Now you know how to solder wires together and to connectors. Next time we’ll look at some of the specific joints and other situations that you will encounter that require soldering when preparing electric flight components.

I hope this post has been useful for you. Please feel free to share it with others and don’t forget to visit my website: www.rookiercflyer.com especially if you are new to flying RC planes.


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Posted October 16, 2015 by Colin in category "Modelling Skills

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