Welcome to Welding

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Metal has been worked by humans for thousands of years. Over time, the techniques and technology used to produce and shape metal goods have been driven by the innovations of science and technology.

Before we dive into some of the technical processes available for welding metal together, let's first take a moment to define a weld. A weld is a fabrication process that joins materials, usually metals or thermoplastics, by fusion. Fusing materials is distinctly different than other kinds of lower temperature metal-joining techniques such as soldering, which do not melt the base metal.

Metal welding is the fusing of two pieces of metal to create one solid continuous piece. All welders work on the same principle: A gas torch or electric welder is used to generate precisely directed heat to melt material, and a filler material is introduced by the operator to complete the fusion.

As these processes became more accessible, we've come so far that you - yes YOU! - can learn how to weld easily.

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Step 1: Who This Class Is For

This class is designed for those who are completely new to welding. Throughout this course, amateur metalworkers will learn ideas and tips about how to become skilled welders, ready to push their making craft to the next level.

Step 2: About Your Instructor

I learned how to weld in college when I took a drop-in advanced sculpture class while constructing my thesis project. I learned primarily Oxy-Acetelene welding to do very fine wire work. To this day, I think Oxy welding is my favorite technique, but it's not practical for every application, and not as fast as MIG.

I learned MIG welding when learning how to repair bicycles in Reno, and my neighbor handed me the gun to their flux-cored 110v welder and said, 'Ok, now you do it'. I explained I had never used a MIG welder before and they turned to me and said: "It's just like using a really hot glue gun." That phrase shot down whatever fears I had about doing a bad job, and I found myself confidently wielding the torch within 20 minutes.

I've taken on large welding projects for Instructables builds, and have done structural welding on sculptures that have traveled around the world.

In short, I'm no pro or expert, but I'm self-taught, experienced and can provide a great pathway to get you metalworking and welding in no time.

Step 3: Different Kinds of Welding

The main types of welding used in industry and by home engineers are commonly referred to as MIG welding, TIG welding, arc welding, gas welding. Hands down, MIG welding is the most common form of welding practiced, but there are other options for fusing metal together.


GMAW or Gas Metal Arc Welding (more commonly called MIG welding) is the most widely used and perhaps the most easily mastered type of welding for industry and home use. The GMAW process is suitable for fusing mild steel, stainless steel as well as aluminum. A few years ago the full name - Metal Inert Gas (MIG) welding was changed to Gas Metal Arc Welding (GMAW) but if you call it that most people won't know what the heck you're talking about - the name MIG welding has certainly stuck.

MIG (Metal Inert Gas welding)is a semi-automatic arc welding process in which a consumable wire electrode and a shielding gas are fed through a welding gun, also known as the torch. The machine produces massive electrical current that travels through the consumable wire to your work pieces fusing and melting both the wire and the base metal together.

MIG welding was developed in the 1940's as a way to speed up the way production welders fuse materials in factories during and after WW2. Seventy years later, the general principle is still very much the same but most MIG welding equipment has been modernized with better parts and some even have onboard computers.

MIG welding uses an arc of electricity to create a short circuit between a continuously fed positive anode (the wire-fed welding gun) and a negative cathode (the base metal being welded). If you want a greater understanding of the core principles of electricity check out the Electronics Class.

The heat produced by the short circuit, along with a non-reactive inert gas, melts the metals under the welding torch and allows them to mix together. Once the heat is removed, the metal begins to cool and solidify, forming a new piece of fused metal.

MIG welding is useful because you can use it to weld many different types of metals: carbon steel, stainless steel, aluminum, magnesium, copper, nickel, silicon bronze and other alloys. This class only goes over how to fuse mild steel, but your welder's manual will have advanced instruction on how to weld other materials.

Oxy welding part of ammunition boxes, 1943 - from the Flickr Creative Commons Public Domain Image Library provided by the State Library of South Australia.

Oxy-Acetylene Torch Welding, more commonly Gas Welding and Cutting, are not used as widely for general welding of mild steel, but great for very delicate assembly of small ornate parts. This form of welding is one of the earliest industrial forms of welding. Gas welding consists of mixing oxygen and acetylene gas to create a flame capable of melting steels. The gas torch is commonly used for brazing softer metals such as copper and bronze, but can also be used for welding delicate aluminum parts such as refrigeration pipes.

Photo of TIG welding torch from ElektraSteel's amazing TIG-Welded Steel Bowl Instructable.

GTAW (Gas Tungsten Arc Welding), or more commonly Tungsten Inert Gas (TIG) welding is comparable to oxyacetylene gas welding and needs quite a bit of hand/eye/foot coordination from the operator. TIG welds are best suited for out high-touch work, such as sculptures and architectural features. TIG welds provide a superior finish that needs minimal clean up by sanding or grinding.

TIG welding provides a very clean way to weld. In one hand you wield a torch electrode and connect ground to your base material. You activate the flow of current with a foot pedal and control the amount of current on the welder. Instead of a consumable wire feed being burned from the torch, the person welding gently feeds filler material from a rod into the welding pool. Since you control the feed of material, slag splatter is minimal. If you are interested in learning more about TIG welding, check out this Instructable.

Welder making boilers for a ship, Combustion Engineering Co., Chattanooga, Tenn. in June of 1942. Photograph by Alfred T. Palmer. From the Flickr Creative Commons - provided by the Library of Congress.

Arc Welding or Shielded Metal Arc Welding (SMAW) is more commonly referred to as stick or arc welding. Arc welding works by clamping a current producing electrode onto a coated consumable stick of material. An electrical arc travels from the tip of the consumable electrode to the base material underneath. The distance between the electrode tip and base material controls the amount of heat being generated by the super hot electrical arc. Arc welding is best suited for structural manufacturing, construction, and large-scale repairs. Arc welds get very very hot, and can burn out thin material easily, thinner materials are more suited to the MIG welding processes.

Step 4: Pros and Cons of MIG Welding

Before going further in this class, please note that the lessons in this course only go over one of the kinds of welding listed above, MIG welding. MIG welding is the most common form of welding, albeit the price tag associated with a MIG welder can be high, it is the most accessible of welding skills to learn. More on that in our upcoming lessons.

Here are some advantages to MIG welding:

  • The ability to join a wide range of metals and thicknesses
  • All-position welding capability, meaning you can weld on vertical and overhanging surfaces with ease
  • A good weld bead, with the right settings
  • A minimal amount of weld splatter (compared to industrial stick welding)
  • Easy to learn

Here are some disadvantages of MIG welding:

  • MIG welding can only be used on thin to medium thick metals. Depending on the welder, I would say the thinnest would be 24GA steel, which is about .0239 inches, and medium thickness is about 1/4" or 5/16" - anything thicker than that, and it's on to stick welding.
  • The use of an inert gas makes this type of welding less portable than arc welding which requires no external source of shielding gas
  • Produces a somewhat sloppier and less controlled weld as compared to TIG welding

Step 5: Quiz

    "id": "quiz-1",
    "question": "What is the oldest form of welding?", 
            "title": "Gas Metal Arc Welding ",
            "correct": false
            "title": "Gas Welding",
            "correct": true
            "title": "TIG Welding",
            "correct": false

    "correctNotice": "That's correct",
    "incorrectNotice": "That's incorrect"
    "id": "quiz-2",
    "question": "MIG welding is suitable for very thick metal materials.",
            "title": "True",
            "correct": false
            "title": "False",
            "correct": true
    "correctNotice": "That's correct",
    "incorrectNotice": "That's incorrect"

Step 6: What's Next?

We'll go over the tools and safety requirements to get going with MIG welding in the Tools and Materials Lesson. This lesson will provide a complete list of all consumable shop supplies and equipment used throughout this course.

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