How to Use a MIG Welder

MIG welding is a great way to add professional touches to your DIY projects. MIG welding has many practical applications, from auto work to home repair. Follow this guide to learn how.

Method 1

Method 1 of 4:

Understanding MIG Welding

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The process is GMAW (Gas Metal Arc Welding), commonly known as MIG welding (Metal Inert Gas welding). MIG welding was developed during World War II as a fast, portable process to create strong, durable joints. Today it is used in many shop and factory applications as well as by home hobbyists and welding enthusiasts.^{[1]XResearch source}
2
Learn how it works. MIG welding uses a machine to feed a wire through a contact tip into a MIG gun. The electrically charged contact tip transfers the welding current to the wire. The arc is established between the wire and the base metal. Often times an inert gas is used, which flows out of the gas nozzle to shield the welding process from the atmosphere.^{[2]XResearch source} There are several modes of metal transfer:
- Short circuit (thin metals)
- Globular transfer (heavier metals)
- Spray transfer (hottest)
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Once you learn how to use a MIG welder, you can make repairs around the home. A MIG welder can be used on stainless steel, mild steel, and aluminium of all thicknesses. Shielding gases will vary depending on base metal and welding wire.^{[3]XResearch source}

Method 2

Method 2 of 4:

Preparing to Weld

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1
Assemble your safety gear. You will need a full set of safety equipment to ensure your safety while welding. This includes gloves, masks, and protective clothing.^{[4]XResearch source}
- Make sure that all of your skin is covered to prevent overexposure from UV rays. You will need a mask with at least a #10 shade or darker. This will help prevent arc eye.
- If you are working in a poorly ventilated area, you will need a vapor mask to minimize the amount of toxic vapors inhaled during the welding process.
- Wear gloves that can protect your skin from molten metal.
- Keep a CO2 extinguisher and a bucket of sand nearby for emergency fires.
2
Select a comfortable MIG gun. Some are shaped like pistols, while others may look like acetylene torches. The size of the machine will depend on the size of the project.
- A MIG gun may also be water or air cooled. Air-cooled guns are used for 200 amps or less and are easier to manipulate in small areas. The air-cooled gun is the type that home MIG welders typically use.^{[5]XResearch source}
3
Prepare the area to be welded in. Remove all flammable material and find a good surface to weld on. Although you can put the ground connection right on the piece you are welding, most shops have a large metal workbench that the ground is hooked up to.
- If there are other people present, set up welding curtains around the work area. This will protect them from UV damage.^{[6]XResearch source}

Method 3

Method 3 of 4:

Installing the Wire

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1
Obtain the proper wire. Use the same wire type as the material you are welding. For example, if you are welding stainless steel, use a stainless steel wire.
- For steel welding, there are two main types of wire. AWS ER70S-3 is an all-purpose steel wire. This is usually the most economical choice. AWS ER70S-6 is a high-quality steel wire, designed for welding on rusty or dirty steel. ^{[7]XResearch source}
- E71TGX requires no shielding gas. It is suited for welding in high winds and for painted or rusty materials.
- Vary the diameter of your wire based on the thickness of the metal you are welding. Use thin wire for thin metals, and thicker wire for thicker metals. You may need a larger machine for thicker metals.
Tighten the tension on the reel so that the wire doesn’t unravel due to its own tension. Make the first 3 inches (7.6 cm) of the wire as straight as possible to avoid tangles or damage to the line feeder. Use a wire cutter to trim the wire accordingly.^{[8]XResearch source}
3
Feed the wire to the torch. Insert the wire into the guide tube and feed it over the roller. Insert it in to the wire liner. If you have to use force, chances are that the wire is not aligned properly.^{[9]XResearch source}
- Make sure the wire is free from rust or grease, this will cause bad welds. Use a dry cloth to clean any dirty wire before inserting it. Wire will become rusty if left in the welder when not in use.
- Once the wire is inserted into the liner, turn the welder on and use the wire feed mechanism to push the wire through the welder.
4
Adjust the tension. Once your wire is fed through, you will need to adjust the tensioner. TOO much tension will cause the mountings to bend, damaging the welder. Keep the tension at the minimum amount that still allows the line to be fed through.^{[10]XResearch source}
- Make sure to check the tension on the reel as well as on the line feeder. Both should be as low as possible.

Method 4

Method 4 of 4:

Making the Weld

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This is reverse polarity.
As you are welding, keep your electrode extended between ¼” and 3/8” from the contact tube. This will help make for a clean, regular weld.
Use carbon dioxide as an economical choice to provide deeper penetration on steel.^{[11]XResearch source} This will be too hot for thin metals though. Use argon for aluminum welding, and a mix of argon (75%) and carbon dioxide (25%) for thinner steel.
4
Weld a joint using a drag or push welding technique. The angle should not exceed 10 degrees in either technique. Keep the wire at the front edge of your weld pool. This will give you greater control over your weld.^{[12]XResearch source}
- Drag welding pulls the bead along with the tip. This will give you a deeper penetration and a narrower bead.
- Push welding pushes the bead with the tip. This will give you a wider bead.
Use the welder to place material directly into the joint. You can use a back and forth method to fill large gaps. For flat joints, hold the gun at a 90° angle.
6
Make a horizontal weld.^{[13]XResearch source} You must lower the gun angle slightly to keep the filler from sagging. Keep the same push or pull angle as normal. Use a back-and-forth weave motion to fill large gaps.
- Keep the amperage the same as a flat weld. You may need to use a slightly smaller diameter wire to keep the weld pool from getting too big.
7
Make a vertical weld.^{[14]XResearch source} For thin materials, start at the top and move the pool down with gravity. This keeps the arc from penetrating the material. For thicker metals, start at the base and work up. This will help increase penetration.
- You may want to lower the amperage by around 10-15% to help fight gravity.
8
Make an overhead weld. Use standard welding techniques, but increase your travel speed. This will help prevent filler from falling out of the joint. You may need to increase your gas flow rate.
- Keep your nozzle clean, as spatter will build up faster when welding overhead.
Once you are done with the weld process, grind off any excess filler. If the weld is defective, grind it down and re-weld the joint.

Expert Q&A

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Question
How do I prepare for MIG welding?
Jones Welding & Industrial Supply Company
Industrial Welding Experts
Welding can be a complex and potentially hazardous activity. The information provided here is meant to serve as a general guideline, but it is crucial to prioritize safety and consult with a qualified welding specialist or instructor if you have any doubts or concerns. Welding techniques, materials, and equipment may vary, and the proper procedures and precautions may depend on specific circumstances. Welding involves inherent risks, such as exposure to high temperatures, intense light, fumes, and electrical hazards. Therefore, it is essential to receive proper training, follow manufacturer's guidelines, and adhere to safety regulations and practices. WikiHow and Jones Welding & Industrial Supply, Inc do not assume any responsibility or liability for any injuries, damages, or losses resulting from the use or misuse of the information provided. Always seek professional advice and take appropriate precautions to ensure your safety when engaging in welding activities. You can always consult with your local welding supply store to be led into the right direction!"
Jones Welding & Industrial Supply Company
Industrial Welding Experts
Expert Answer
Familiarize yourself with the equipment and learn about the various parts of the MIG welder, including the wire feeder, welding gun, and gas regulator. It's also important to prepare the workpiece—clean the metal surfaces you're going to weld to ensure good penetration and adhesion. Remove rust, paint, and other contaminants using a wire brush or grinder.
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Can a gas leak from welding be harmful?
T. Chinsen
Top Answerer
Any gas can be inhaled and become harmful if inhaled in sufficient quantities. The gases reduce the oxygen level of the air when they are present. Aspirators absorb toxic gas and stop it from being inhaled into the body.
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I am replacing the floor pans on a VW. Which welder should I use?
Community Answer
In general, the GMAW/MIG or Stick will work. If you don't know how to use a MIG welder, then get a skilled MIG welder to teach you how or take a welding class at a local community college. Learning on the fly is not sound or safe. Have your VW pan welding checked out by a skilled welder.
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Tips

Keep the gun straight so you won't crimp the wire feed.
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Practice on a scrap piece of metal that is similar to your project to get the feel for the MIG welding process. This will help you to adjust for the correct Voltage/Amps and wire speed (too high voltage/amps burns holes in your material, too low will only place a weld bead on top of the work piece and not actually melt/fuse the 2 pieces together strongly. Wire speed is more difficult to explain, but basically, too slow will mean you have to hold the nozzle extremely close to the workpiece and keep getting stop/start "popping" arcs, too fast wire speed will also produce stop/start "popping" arcs, with noticeable lengths of wire coming out.)
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An ideal welding voltage/amps setting is one that produces a "flat as possible" weld, without burning holes through the workpiece.
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Warnings

Always wear a welding helmet when undertaking welding of any kind or looking at an arc of any kind (mig, tig, arc, fcaw, etc) Failure to do so will result in a condition known as "arc eye", an inflammation/ burn of the eye caused by the intense UV light caused from the arc while welding. This will typically not be felt until several hours after the damage has been done, usually when trying to go to sleep.
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It is also Highly recommended to Always wear closed shoes, long sleeve shirts, long pants, and gloves, not only to protect from slag (small pieces of molten metal caused from arc welding) but to also protect from sunburn that can be caused from the UV light from arc welding.
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Always be aware that a workpiece you have just welded will remain extremely hot for quite a while, so make sure other people are aware of this and they do not attempt to handle the workpiece without gloves.
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