HOW TO WELD WITH A MIG WELDER
Welding with gas can look difficult, so lets make it easy by breaking it down step by step.
Updated: Jan. 31, 2025
CHOOSING YOUR WELDER
We recommend a multi-purpose welder because you’ll be able to transition between flux core, MIG, TIG, or stick welding.
We picked up an Eastwood MP140i multi-purpose welder on a Black Friday for $500.
It comes with everything you need to start MIG welding except welding gas. We also built a comparison tool to compare popular welding brands such as Eastwood vs Harbor Freight vs Yeswelder here.
You could go with something less expensive like a flux welder, but flux will run much hotter. If you plan to weld automotive sheet metal, flux is possible but also more difficult. Flux will also result in more splatter, leading to additional work.
WHERE CAN I FIND WELDING GAS?
The first thing you're going to need for your MIG welder is welding gas. The MIG calls for using 75% argon and 25% CO2 welding gas. The easiest way to find welding gas is to open Google or Apple Maps, type "welding gas" and see what comes up.
Here are some options near you that might carry welding gas.
Tractor Supply Select Stores
Northern Tool Select Stores
We ended up purchasing a 40 CF size cylinder from Airgas. They had much larger sizes, but since we won't be welding every day, 40 CF should be fine.
While you’re at it buy a welding cart too. You can pick one up from Eastwood.com using our 10% off discount code of THEBUILD10 during checkout.
HOW TO SETUP A WELDER
FIRST, you need to hook up the gas and regulator. Some welders like the Eastwood MP140i includes a regulator. The regulator is required to adjust the pressure of the gas as it flows from the cylinder through the welder and out of the stinger.
The regulator attaches by screwing it into the gas cylinder. All the gas attachments are made to seal without any pipe sealing or threading, so DON’T use any.
Once your regulator is tightened with a hand wrench hook up the hose from the regulator to the welder.
Repeat tightening everything with a wrench and don’t over-tighten the fittings.
You can then use soapy water to check for any gas leaks once you open up the gas cylinder.
The Eastwood also comes with a few other essentials to get you started. You have your ground attachment, which attaches in a specific placement for MIG, and another attachment for your stinger or welding gun.
Depending on the type of welding you're doing, these will go into different places, so refer to the manual to check where the ground gets plugged into. This will vary depending on if you are MIG or flux welding.
FEEDING THE MIG WIRE
Inside the welder, you need to feed the MIG wire into place. The Eastwood came with 0.023 wire size, perfect for the variety of sheet metal sizes we'll be welding.
STEPS TO FEED MIG WIRE THROUGH WELDER
Remove the bigger spool holder on the welding wire spool holder if using a smaller welding wire spool.
Insert the smaller wire spool one using washers, springs, and nuts to secure it.
Hold the wire spool and feed the wire through the welding tensioner.
Release tension on the nut holding the wire spool as necessary.
Lock the welding tensioner into place.
Turn the machine on and pull the trigger to feed the wire through the stinger (welding gun). Note: you don’t need gas yet and make sure there’s nothing to ground to.
Clip the wire out of the stinger nozzle feed to leave about 1/2 inch out from the nozzel.
SAFETY FIRST
For safety, you'll need a flame-retardant shirt, welding gloves, a welding mask, a welding blanket, and a fire extinguisher. Make sure you always set your welding mask to the appropriate darkening level.
We always use a propane spark torch igniter to test that auto dim works correctly before we start welding.
HOW TO SETUP MIG GAS
One of the easiest steps is turning on the gas. Right is tight and left is to loosen. You don’t need to loosen it all the way. We typically loosen the tank slightly. That way if you need to close it quick, it doesn’t take too much turns.
STEPS TO CONNECT WELDING GAS TO WELDER
Crank the gas regulator to the open position. Left is loosen and right is tighten.
Adjust the regulator to the correct setting, which the manual suggests around 20 Kg.
Pull the MIG welding stinger (gun) trigger without making any contact to metal to make sure gas and wire flows properly.
Clip excess wire from the stinger nozzle feed and leave about 1/2 inch exposed from the nozzel.
MIG SETTINGS
We're going to be welding some thinner sheet metal first, around 22 gauge, which calls for a voltage set to six and a wire feed set between 2.5 and 4.
MIG WELDING VOLTAGE AND WIRE SPEED SETTINGS STEPS
Set the voltage knob to 6 and a wire feed set between 2.5 and 4.
Attach your ground clap to the piece of metal
Bring your stinger to the welding location, lower your mask with the appropriate shade set, pull the trigger, and release
For thin sheet metal you’ll want to tack weld. Meaning you want to weld in small increments. As you increase your thickness of metal, you’ll want to also increase your voltage and wire feed.
For thicker metal say 16 gauge and up you can run a continuous weld instead of tacking.
PRACTICE WELDING
Continue to practice by tack welding or making spot welds. You can also use a copper backplate as a heat sink to help prevent blowouts. Use different thicknesses of material. Try butting, overlapping, and tree joints.
WHAT IS THE BIGGEST MISTAKE IN MIG WELDING?
Practice is key and what you’ll find is the biggest mistake when MIG welding is the WRONG settings. Based on different thickness of material and how you are welding the material along with settings is the biggest issue.
You’ll make the mistake of having the wire feed too high or voltage set incorrectly. This can lead to poor penetration or blowout with thin sheet metal. So practice a small run or tack and check your work. Then fine tune the settings to avoiding mistakes with your next MIG welding project.
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