Mastering Your First MIG Welder:

A Beginners Guide

Embarking on your MIG welding journey? This step-by-step guide will walk you through the essential setup and usage of your MIG welder, making the process easy for beginners. Let’s dive into the world of Metal Inert Gas (MIG) welding, covering everything from safety precautions to the basics of creating impressive welds for your DIY projects.

This article will teach you:

• How to set up your MIG welder
• What shielding gas to use and how to attach it to your machine
• How to select the welding wire and how to install it
• How to hook up all of the cables and which polarity to use
• Individual settings most MIG welders have
• Basics of MIG welding for beginner-level DIY projects

Welding Safety:

Prioritising safety before igniting your MIG welder is essential. It is important to equip yourself with a welding helmet and gloves designed for MIG welding. Welding produces dangerous UV and IR radiation that can seriously damage your eyesight. On top of a welding helmet, you’ll need gloves rated for MIG welding not TIG welding. This is because MIG welding will expose you to more molten spatter particles. So get yourself a pair of robust leather gloves, a sturdy welding apron, boots, and pants. Ensure a flame-free workspace, have a fire extinguisher nearby, and always work in a well-ventilated area to protect against harmful UV and IR radiation emitted during welding.

MIG Welding Theory:

Metal inert gas, or MIG for short, is an arc welding process. And like all other arc welding processes, it melts and joins the base metal with the filler metal. It does this by using the resistance of current flow through the metal. When electricity flows through the metals like steel, stainless, aluminium, copper, and others, the materials resist the flow of electrons. This then creates heat and melts the material if the current flow is high enough. Some metals like carbon steel are easier to melt because they have a high resistance to current flow. While metals like copper readily accept electricity flow, and it takes more electricity to melt them.

The power source, your MIG welder, prepares the electricity according to your settings. It then flows through the MIG welding gun and into the MIG wire that sticks out of the MIG gun. Once this electrically is charged, wire comes into contact with the welded metal. The current makes a full circle: power source > MIG gun > ground clamp > power source, and flows through this circuit. However, the metal (wire and the base metal) resists the current flow and heats up to the point of melting, which fuses the materials together. That’s the essence of how MIG welding works.

Setting Up Your MIG Welder:

Start by thoroughly reading your MIG machine’s operator’s manual, emphasising safety and limitations. Inside the box, you’ll find crucial components. These include the power cord, MIG gun, ground clamp, consumables, and drive rollers. If your project involves welding aluminium, consider purchasing a spool gun separately.

Shielding Gas:

MIG welding requires the shielding gas to protect the molten weld from atmospheric contamination and oxidation. But, the shielding gas also influences the weld quality and characteristics. This is mainly the arc stability, spatter, depth of penetration, and bead width. You should choose gas compositions based on the metal you’re welding. For carbon steel, use 100% CO2 or a 75/25 mix of argon and CO2. Stainless steel benefits from a Tri-mix of helium, argon, and carbon dioxide. While aluminium requires 100% argon with the option to add helium for better penetration.

You’ll also need a shielding gas regulator if you already have a welding cylinder. This regulator is attached to the shielding gas bottle, and its job is to regulate how much shielding gas pressure is released for the flow over the weld puddle. 

Thread the shielding gas regulator carefully on the shielding gas bottle and tighten it snuggly. Stay clear of the regulator’s way in case the regulator is faulty because the gauge on the regulator may explode and harm you. Remember always carefully read the safety instructions for using the shielding gas regulator and the pressurized gas bottle safety tips from OSHA. Once the regulator is set, establish the line between the regulator and the MIG welder with the hose.

Welding Wire:

You can use a solid filler metal wire to MIG weld in the true sense of the word. Or you can use a self-shielded flux-cored wire to join metal with the flux-cored welding process. 

• Solid metal MIG wires require a shielding gas, as described above. 
• Flux-cored wires quite literally have a flux inside their hollow core. This core protects the molten weld pool from the atmosphere. You don’t need to use a shielding gas if the wire is a self-shielded flux-cored wire.

Select a MIG wire that matches the type of metal you are welding. You can see the available solid wires from in our chart below:

Use smaller diameter wire for welding thinner sheets of metal and larger wire to weld thicker sections. 

Wire Roller

Before installing the wire spool in your machine, you must ensure the correct wire roller is installed in the wire drive system. Use the V-groove (smooth wire guides) roller to feed the solid MIG wire and the W-groove (serrated wire guides) for flux-cored wires. For more on choosing the right MIG wire, check out our previous article, Choosing Between Flux-Cored Wire and Solid MIG Wire

To change the wire roller, you will need to:

• Loosen the tensioner
• Lift the guiding roller up
• Unscrew the plastic cap that holds the main roller (V or W)
• And replace it with the one you need for your wire.

In addition, each of these rollers has two guiding lines, one is for the 0.030” wire and another for the 0.035” wire. So, you need to set the roller for the wire size as well.

Wire Spool

To install the spool of wire, remove the large plastic “knob” to get to the plastic post with the guiding pin. Next, take your wire spool and slide it onto the plastic post so that the guiding pin goes through the dedicated hole on the wire spool. In addition, your wire spool must be installed so that the wire unwinds from underneath into the wire drive mechanism. Never install the spool by unwinding from above the wire drive; that’s just a bad practice that leads to poor wire tension, tangling, and other issues.

Before attempting to install the spool, make a firm grip over the wire and hold it firmly as you are installing. If you release the wire, it can easily unwind rapidly before you get the chance to manually guide the end of the wire through the wire drive system and into the MIG gun. Once you push some wire into the MIG gun liner, lower the upper roller, and latch it up with the tensioner. It can be challenging to push the tip of the wire into the MIG gun liner as you are holding the wire to prevent sudden unwinding. However, you can hold the wire with one hand and use a screwdriver or a similar tool to precisely manipulate the wire’s tip into the MIG gun liner

Polarity:

Understanding polarity is crucial for MIG welding. Standard MIG welding requires a Direct Current Electrode Positive (DCEP) polarity. While Flux-cored welding uses Direct Current Electrode Negative (DCEN). Two common ways to switch polarity on the MIG machines are via a bus bar or wire connection inside the filler metal wire compartment. Or by using the DINSE plugs in front of the machine to switch polarity.

If you own a welder like the MIG285 285-Amp MIG Welder, you’ll need to manually switch the bus bar connection. Simply switch the “+” sign for MIG welding, and to the “-” sign for Flux-cored welding.

However, if you own a welder like the MTS200 200 Amp 3-in-1 Welder, all you have to do is attach the pre-installed DINSE plug on the front of the unit to one of the DINSE sockets right next to it. To MIG weld, connect the plug to the “+ positive” DINSE socket, or if you wish to use a Flux-cored welding process, plug it into the “- negative” DINSE socket. This will change the polarity of the wire in the MIG gun. But, you must also attach the ground clamp to the opposite DINSE socket to complete the circuit. So the ground is connected to the negative DINSE connector to MIG weld, and positive for Flux-cored welding.

MIG Welder Settings:

Your MIG machine can have a lot of settings or only a few, depending on the brand and if it’s a hobbyist machine or for professional work. Our MIG machines are typically loaded with features, regardless if you are a hobbyist or a full-on professional working in the field. 

We’ll quickly explain the most prominent MIG welder settings to help you use your machine to its maximum capabilities. But, we can’t dissect every feature in tiny details because this text would be too long.

Voltage, Amperage, And Different Modes of Arc Transfer

Besides the filler metal deposition rate, arc’s heat, and depth of penetration, adjusting your voltage and amperage (in the case of MIG welding, that’s your wire feeding speed), you’ll also set your metal transfer type.

The two basic metal transfer types are short circuit and spray transfer for MIG welding. 

Circuit Transfer

The most common MIG settings for voltage and wire feeding speed (WFS) will put you in the standard short circuit MIG transfer. The short circuit mode basically melts the wire at the point of contact with the welded joint many times a second. The wire from the MIG gun touches the metal, creates a short circuit which causes the resistance to current flow to grow rapidly. As a result, the wire’s tip is melted into the joint, and the process keeps repeating as the MIG gun pushes more wire to cause a short circuit with the welded material. This arc transfer method is identified by a lot of spatter and the standard MIG sizzling sound like bacon frying in the pan. 

Spray Transfer

But if you raise your voltage and WFS substantially, you’ll enter the spray arc transfer mode. Every machine has slightly different settings you need to use to enter the spray arc transfer. So you have to experiment a little on a piece of scrap metal. You’ll recognize entering the spray transfer once the arc doesn’t produce a spatter, and the process makes high deposition of the filler metal rapidly. In addition, the spray transfer produces a more quiet, hissing arc, without the crispiness associated with the short circuit mode. 

The required voltage and WFS settings are also influenced by the wire’s diameter and the welded metal. So, thicker wires require more current. 

Typically, you would use a spray transfer mode when welding thick joints or doing out-of-position welding, and short circuit MIG for welding thin sheets of metal. While this satisfies most welding needs, welding costly stainless steel thin sheets of metal is not ideal if the short circuit spatter harms the appearance of the welded part. 

So, to use the best of both worlds, you can use pulsed MIG welding. In a nutshell, pulsed MIG oscillates between the high amperage needed for penetration and the low amperage that keeps the puddle cool to prevent burn-through. The high amperage portion of the pulsed arc provides the spray transfer mode, so there is little to no spatter, but you are less likely to burn the thin stock thanks to the low current part of the cycle.

Other MIG Welder Settings

Let’s start with the Synergic MIG setting, the most helpful and the most impactful setting found on MIG machines. 

The Synergic MIG reduces much of the guesswork when it comes to the voltage and WFS settings. This is because it automatically adjusts both according to your selected amperage or material thickness. As a result, even a complete beginner can have a good starting point when setting up their MIG machine. Of course, you can always adjust your settings manually by turning the Synergic MIG off and adjusting the voltage and WFS independently to fine-tune the arc transfer to your liking.

The wire diameter selector button allows you to select the wire you’ve installed in your machine to optimise the power output for that specific diameter. 

One particular setting many people don’t use to their advantage is the MIG inductance setting. Some MIG machines include the inductance setting, which you can manually set to produce a softer arc with less spatter or improve penetration and arc force. Fine-tuning the inductance can help you when welding thin sheets of metal, you don’t need maximum penetration, and when reduced spatter is desirable.

MIG Welding Basics:

Once your MIG welder is set up and you have selected the polarity, installed the wire, connected the shielding gas hose from the regulator to your MIG welder, and put on your PPE, then it’s time to lay the first welds! It’s best to practice on scrap metal to determine the optimal welding speed and settings. Clean the metal surface thoroughly for better conductivity and aesthetics. 

To achieve better penetration, drag the MIG gun away from the weld pool so that the wire is pointed back into the bead. But if you weld thin gauge, you can use the push technique and push the gun ahead of the bead to reduce penetration and lower the chance of burn-through.

Hold the MIG torch with both of your hands to improve precision and stability, keep the wire to work distance consistent at about 3/8 to 1/2 inch, and keep the torch as straight as possible. 

You’ll achieve better results on thin metal sheets if you first space out your tack welds before welding the seams. Evenly spaced tack welds prevent warping and hold the pieces in place before you place the final weld along the joint line. 

Final Thoughts:

MIG welding offers a straightforward and efficient way to join metals, making it a favourite for hobbyists and professionals alike. With the knowledge gained from this guide, you’re well on your way to mastering the art of MIG welding. Happy welding!

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