Master weldors make welding look so easy and so essential that many of us are tempted to rush out to the nearest tool store and buy a full featured TIG machine – even if we don’t know what TIG stands for, what it does, how it works, or how to use it. We’ve been lured by custom bike builders in magazine articles or TV programs where, without apparent thought, they grab an always handy, ready-to-go welding torch; snap down their welding helmet; and merrily fuse the seams of an aluminum gas tank. Their welds of orderly, evenly spaced, identical swirls are so perfect you think that’s the way the bead flows out of the stick.

Before you go on that shopping spree, let’s talk to a real world weldor and get a better idea of what this welding thing is all about. What is it? What is the difference in Stick, MIG, and TIG? How does it work? Is it that simple?

Let me introduce Mr. Kent Weeks (aka Mr. Devil) the master weldor at Lucky Devil Metalworks in Houston, Texas. He is definitely one of those craftsmen who really can make welding look easy.

Over Kent’s career he has worked as a professional fabricator and weldor on a wide variety of things from large industrial parts, handicap vehicles, elevators, wheelchair lifts to hot rods and custom bikes. He’s worked with exotic specialty materials, performed micro-welding, and operated machine shop equipment. But it’s Kent’s passion for welding that lead him to run The Best Little Fabhouse In Texas where he builds custom motorcycles and customizes stock motorcycles. Kent says he’s had the opportunity to learn how to use all kinds of equipment from different welding processes and fabrication tools but that he hasn’t done or seen it all. Good thing too ‘cause it would only make his head bigger.

What is Arc-Welding?

Arc welding is a fusion process that joins metals by using an electric arc to apply intense heat at the joint between two pieces of metal. The metal is melted and caused to intermix usually with an intermediate molten filler metal. When cooled and solidified, the metals are permanently bonded together with the joint having the same physical properties as the original metals. For convenience, we’ll refer to arc-welding as just welding from here on out.

The basic welding circuit consists of a power source connected by a work cable (often called the ground) to the work piece and by a electrode cable (often called the hot cable) to a holder with a welding electrode. An arc is created with the electrode tip touches the work piece and is withdrawn a short distance. The arc produces a temperature of about 6500°F at the tip that melts the base metals at the joint.

Since metals at high temperature react to the oxygen and the nitrogen in the air, the molten pool must be shielded by an inert gas or slag. This shield prevents bubbles forming in the weld which would weaken it. The basic welding circuit is the same regardless of the welding process.

The three commonly used welding processes are:

1. Stick Electrode or Shielded Metal Arc Welding (SMAW)
2. MIG for Metal Inert Gas or Gas Metal Arc Welding (GMAW)
3. TIG for Tungsten Inert Gas or Gas Tungsten Arc Welding (GTAW)

Stick Electrode

Kent says that stick welding is perhaps the oldest form of arc-welding, having been around for decades, like his grandfather’s old cracker box. These simpler machines are common in many garages, home shops, and farms. While they aren’t used as much in the motor sports industry, the process still has a solid place for rough fabrication, repair work on fences and trailers, and especially in heavy industry such as oil field work, mobile welding, large equipment repair, building construction, and underwater welding.

Stick or SMAW welding requires a holder for the replaceable welding rod (or electrode). The rod completes the electrical circuit and is consumed by the welding arc. The rod supplies both the filler metal for the weld bead and a chemical coating that when burned creates protective gasses to shield the molten metal. Since there is no need for a bottle of inert gas, the stick welding process is the simplest and requires the least equipment. Welding rods are available in a wide variety of sizes, materials, and coatings.

Stick welding can be used for almost any application. Its main disadvantage is that the slag leaves a messy weld and there is usually more spatter than other processes. The spatter and the slag must be chipped and cleaned away before painting. Also, starting the arc requires a light hand. Most beginners will burn up a lot of rods sticking them to the work material.

MIG

MIG or GMAW welding is a well established and easy to use process that’s also common in many home garages these days. MIG welding can be used in almost any application. It’s most useful for light to medium fabrication projects.

MIG welding uses an electrode cable that includes the circuit wire, a tube for the filler wire, and a tube for the inert shielding gas. The cable ends in a MIG gun with a trigger which activates the electrical circuit, the wire feed, and the gas flow. The filler material is fed by the machine from a spool to the gun.

Kent uses his 220 single-phase MIG welder mostly for welding fixtures and occasionally for use on light fabrication and automotive projects. In it he runs .035 thick ER70S-6 welding wire which is designed for welding mild steel material from 18 Gauge to ¼-inch thick material. He uses .025 wire for lighter sheet metal work. A variety of wire gauge sizes is available for use on thinner or thicker material as well as different alloys such as stainless.

Of course, each wire size and welding situation requires a change in the MIG gun tip, arc temperature (determined by voltage and amperage settings), and wire feed speed. You will find temperature and wire feed setting info on the back of the door to the spool compartment on most models regardless of the manufacturer. Kent recommends fine tuning your set-up by making a test pass on some scrap material before welding your work piece.

To shield mild steel welds, Kent uses a bottle of C25 mix made up of 75% argon and 25% CO2 (carbon dioxide). To shield stainless steel welding, you need to change your gas to ether pure argon or Blue max (90% helium, 7.5% argon and 2.5% CO2).

To use MIG to weld aluminum, Kent says you’ll need to use pure Argon gas and to purchase a spool gun to run aluminum welding wire. Spool guns are designed just like they sound; they hold a small spool of welding wire right in the gun itself. This is necessary because the aluminum wire is too soft to be pushed through the lead on a normal gun. This process is messy but it sure gets the job done in a jiffy.

Smaller MIG welders are a good option for custom bike projects in the home garage. A machine like the Lincoln Power MIG 140 is fine for mounting tabs and basic sheet metal work. It’s designed to weld from 24 gauge to 10 gauge mild steel in a single pass with .025 welding wire. If you have to weld thicker material then run multiple passes and pre-heat the work material.

TIG

TIG or GTAW (or for you really old guys, Heli-Arc) welding is a very powerful welding process because it gives the weldor almost complete control of all the welding elements to achieve welds of great beauty, strength, and quality. However, that control brings additional complications requiring a higher degree of knowledge and skill than either stick or MIG. While TIG can be used for almost any application, it is the number one process chosen by professionals in the motor sports industry. Why? Because TIG is a very good process for welding nonferrous metals (aluminum etc.) and stainless steel.

Mention welding to Kent and he will quickly inform you that TIG is his favorite; that he tolerates MIG as a useful, but distant, second, and that stick is at the level of cavemen pounding bronze ore with rocks. Kent has invested significant time and energy (as you would expect from a man following his passion) to learn the intricacies of the TIG process and to develop the expert skills with the equipment. And he’s not afraid to use it.

The controls on a TIG welding torch are a little more complicated than MIG gun. Instead of a trigger to turn on the flow of power, gas, and filler metal, TIG uses a foot pedal which variably controls the power output within the selected range. A tungsten electrode is used inside the torch to put the power to the work piece and a welding rod is used to manually feed material to the weld bead in a method similar to oxy-acetylene welding. Starting with MIG experience and learning to TIG weld is sort of like learning to drive a car with an automatic then switching to a manual. You realize you got a lot more to do but you have a lot more fun.

The pointed pin sticking out of the cup of the torch is the tungsten electrode. Its function is to create the arc between the work piece and torch. The tungsten electrode is a non- consumable part and it is important to keep it clean and sharpened to a fine point in order to make a nice looking weld. So if you take it for a dip in the base metal or slam your filler rod into it then you need to clean it up on a grinding wheel or belt sander.

Tungsten electrodes come in many different sizes. Kent uses 3/32-inch the most. For thicker frame pieces he steps up to 1/8-inch and for thinner material he goes down to 1/16- inch. He also has even smaller ones for micro welding but doesn’t get many opportunities to use them. The tungsten electrode also comes in different tungsten alloys. Kent uses thoriated tungsten, which includes 2% thorium oxide, to weld mild steel, stainless steel, etc. and pure tungsten for welding aluminum.

For welding in tight spots, Kent ran across some new Weldcraft torches (the WP-150/200 Series and the WP-125 Micro-TIG Torches) which are designed for advanced projects. These styles are extremely helpful in a fast-paced welding shop or in the hands of a serious motorcycle fabricator.

First of all, the heads on these torches can be changed in seconds without the need for tools. This allows Kent to have a variety of head assemblies ready to go at all times. For all around projects on light sheet metal, he has a straight head, a 90-degree head and a special 90-degree head without a back- cap for extra tight spots. Then for thicker materials like framework, Kent keeps both a large style straight head and a 70-degree head ready. All these are set up with tungsten electrodes, cups and back caps - ready to weld at all times. This flexibility allows Kent to jump from one project to the other.

Secondly, these torches are available for air or water-cooled applications and they are compatible with WP-20 hoses, cables and handles. For those who don’t know (like me), WP-20 style torches are standard on most TIG welders, so chances are you can upgrade your existing power cable to get started and save a few bucks in the process.

The WP-125 Micro-TIG Torches are great for super tight spots where even flex-heads can’t reach. This rascal can get down in a 5/8-inch diameter hole for nearly impossible welding work. These torches are rated for 10-125 amps (DCSP), 100% duty cycle with quarts nozzles. 3/32-inch chucks are available for increased capacity to 160 amps to weld 1/8-inch mild steel in a single pass.

While too many to adequately cover in this simple article, it’s worth noting that a large number of components and assemblies for the TIG torch are available depending on the welding situation. These include different sized gas cups and back caps; straight or angled torch heads; and air or water cooled heads. Check with your welding suppliers for configurations, which will fit your welding machine.

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