Introduction: How to Weld - MIG Welding

Picture of How to Weld - MIG Welding

This is a basic guide on how to weld using a metal inert gas (MIG) welder. MIG welding is the awesome process of using electricity to melt and join pieces of metal together. MIG welding is sometimes referred to as the "hot glue gun" of the welding world and is generally regarded as one of the easiest type of welding to learn.

**This Instructable is not intended to be THE definitive guide on MIG welding, for that you might want to seek out a a more comprehensive guide from a professional. Think of this Instructable as a guide to get you started MIG welding. Welding is a skill that needs to be developed over time, with a piece of metal in front of you and with a welding gun/torch in your hands.**

If you are interested in TIG welding, check out: How to Weld (TIG).

Step 1: Background

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MIG welding was developed in the 1940's and 60 years later the general principle is still very much the same. MIG welding uses an arc of electricity to create a short circuit between a continuously fed anode (+ the wire-fed welding gun) and a cathode ( - the metal being welded).

The heat produced by the short circuit, along with a non-reactive (hence inert) gas locally melts the metal and allows them to mix together. Once the heat is removed, the metal begins to cool and solidify, and forms a new piece of fused metal.

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 your talking about - the name MIG welding has certainly stuck.

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.

Here are some advantages to MIG welding:

  • The ability to join a wide range of metals and thicknesses
  • All-position welding capability
  • A good weld bead
  • A minimum of weld splatter
  • Easy to learn

Here are some disadvantages of MIG welding:

  • MIG welding can only be used on thin to medium thick metals
  • 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 (Tungsten Inert Gas Welding)

Step 2: How the Machine Works

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A MIG welder has a couple of different parts. If you open one up you will be able to see something that looks like what is pictured below.

The Welder

Inside the welder you will find a spool of wire and a series of rollers that pushes the wire out to the welding gun. There isn't much going on inside this part of the welder, so it's worth it to take just a minute and familiarize yourself with the different parts. If the wire feed jams up for any reason (this does happen from time to time) you will want to check this part of the machine out.

The large spool of wire should be held on with a tension nut. The nut should be tight enough to keep the spool from unraveling, but not so tight that the rollers can't pull the wire from the spool.

If you follow the wire from the spool you can see that it goes into a set of rollers that pull the wire off of the big roll. This welder is set up to weld aluminum, so it has aluminum wire loaded into it. The MIG welding I am going to describe in this instructable is for steel which uses a copper colored wire.

The Gas Tank

Assuming you are using a shielding gas with your MIG welder there will be a tank of gas behind the MIG. The tank is either 100% Argon or a mixture of CO2 and Argon. This gas shields the weld as it forms. Without the gas your welds will look brown, splattered and just generally not very nice. Open the main valve of the tank and make sure that there is some gas in the tank. Your gauges should be reading between 0 and 2500 PSI in the tank and the regulator should be set between 15 and 25 PSI depending on how you like to set things up and the type of welding gun you are using.

**It's a good rule of thumb to open all valves to all gas tanks in a shop only a half turn or so. Opening the valve all the way doesn't improve your flow any more than just cracking the valve open since the tank is under so much pressure. The logic behind this is so that if someone needs to quickly shut off gas in an emergency they don't have to spend time cranking down a fully open valve. This might not seem like such a big deal with Argon or CO2, but when your working with flammable gases like oxygen or acetylene you can see why it might come in handy in the event of an emergency.**

Once the wire passes through the rollers it is sent down a set of hoses which lead to the welding gun. The hoses carry the charged electrode and the argon gas.

The Welding Gun

The welding gun is the business end of things. It's where most of your attention will be directed during the welding process. The gun consists of a trigger that controls the wire feed and the flow of electricity. The wire is guided by a replaceable copper tip that is made for each specific welder. Tips vary in size to fit whatever diameter wire you happen to be welding with. Most likely this part of the welder will already be set up for you. The outside of the tip of gun is covered by a ceramic or metal cup which protects the electrode and directs the flow of gas out the tip of the gun. You can see the small piece of wire sticking out of the tip of the welding gun in the pictures below.

The Ground Clamp

The ground clamp is the cathode (-) in the circuit and completes the circuit between the welder, the welding gun and the project. It should either be clipped directly to the piece of metal being welding or onto a metal welding table like the one pictured below (we have two welders hence two clamps, you only need one clamp from the welder attached to your piece to weld).

The clip must be making good contact with the piece being welded for it to work so be sure to grind off any rust or paint that may be preventing it from making a connection with your work.

Step 3: Safety Gear

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MIG welding can be a pretty safe thing to do so long as you follow a few important safety precautions. Because of MIG welding produces lots of heat and lots of harmful light, you need to take a few steps to protect yourself.

Safety Steps:

  • The light that is generated by any form of arc welding is extremely bright. It will burn your eyes and your skin just like the sun will if you don't protect yourself. The first thing you will need to weld is a welding mask. I am wearing an auto-darkening welding mask below. They are really helpful if you are going to do a bunch of welding and make a great investment if you think you will be working with metal often. Manual masks require you to jerk your head dropping the mask into position or require to use a free hand to pull the mask down. This allows you to use both your hands to weld, and not worry about the mask. Think of protecting others from the light as well and use a welding screen if it's available to make a border around yourself. The light has a tendency to draw on lookers who might need to shielded from being burned too.
  • Wear gloves and leathers to protect yourself from molten metal splattering off of your work piece. Some people like thin gloves for welding so you can have a lot of control. In TIG welding this is especially true, however for MIG welding you can wear whatever gloves you feel comfortable with. The leathers will not only protect your skin from the heat produced by welding but they will also protect your skin from the UV light produced by welding. If you are going to be doing any amount of welding more than just a minute or two you will want to cover up because UV burns happen fast!
  • If you are not going to wear leathers at least make sure that you are wearing clothing made from cotton. Plastic fibers like polyester and rayon will melt when they come into contact with molten metal and will burn you. Cotton will get a hole in it, but at least it won't burn and make hot metal goop.
  • Do not wear open toed shoes or synthetic shoes that have mesh over the top of your toes. Hot metal often falls straight down and I have burned many holes through the tops of my shoes. Molten metal + hot plastic goo from shoes = no fun. Wear leather shoes or boots if you have them or cover your shoes in something non-flammable to stop this.

  • Weld in a well ventilated area. Welding produces hazardous fumes which you shouldn't breathe in if you can avoid it. Wear either a mask, or a respirator if you are going to be welding for a prolonged amount of time.

Important Safety Warning

DO NOT WELD GALVANIZED STEEL. Galvanized steel contains a zinc coating that produces carcinogenic and poisonous gas when it is burned. Exposure to the stuff can result in heavy metal poisoning (welding shivers) - flu like symptoms that can persist for a few days, but that can also cause permanent damage. This is not a joke. I have welded galvanized steel out of ignorance and immediately felt it's effects, so don't do it!

Fire Fire Fire

Molten metal can spit several feet from a weld. Grinding sparks are even worse. Any sawdust, paper or plastic bags in the area can smolder and catch fire, so keep a tidy area for welding. Your attention will be focused on welding and it can be hard to see what's going on around you if something catches fire. Reduce the chance of that happening by clearing away all flammable objects from your weld area.

Keep a fire extinguisher beside the exit door from your workshop. CO2 is the best type for welding. Water extinguishers are not a good idea in a welding shop since you are standing next to a whole lot of electricity.

Step 4: Prep for Your Weld

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Before you start welding make sure things are properly setup at both the welder and on the piece you are about to weld.

The Welder

Check to make sure that the valve to the shielding gas is open and that you have around 20ft3/hr flowing through the regulator. The welder needs to be on, the grounding clamp attached to your welding table or to the piece of metal directly and you need to have proper wire speed and power setting dialed in (more on that later).

The Metal

While you can pretty much just take a MIG welder, squeeze the trigger and and touch it to your work piece to weld you won't get a great result. If you want the weld to be strong and clean, taking 5 minutes to clean your metal and grind down any edges that are being joined will really help your weld.

In the picture below randofo is using an angle grinder to bevel the edges of some square tube before it gets welded onto another piece of square tubing. By creating two bevels on the joining edges it makes a little valley for the weld pool to form in. Doing this for butt welds (when two things are pushed together and joined) is a good idea.

Step 5: Laying a Bead

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Once your welder is set up and you have prepped your piece of metal it's time to start focusing on the actual welding.

If it's your first time welding you might want to practice just running a bead before actually welding two pieces of metal together. You can do this by taking a piece of scrap metal and making a weld in a straight line on its surface.

Do this a couple of times before you start actually welding so that you can get a feel for the process and figure out what wire speed and power settings you will want to use.

Every welder is different so you will have to figure these settings out yourself. Too little power and you will have a splattered weld that won't penetrate through your work piece. Too much power and you might melt right through the metal entirely.

The pictures below show a few different beads being laid down on some 1/4" plate. Some have too much power and some could use a little more. Check out the image notes for the details.

The basic process of laying a bead is not too difficult. You are trying to make a small zig zag with the tip of the welder, or little concentric circles moving your way from the top of the weld downward. I like to think of it as "sewing" motion where I use the tip of the welding gun to weave the two pieces of metal together.

First start laying beads about an inch or two long. If you make any one weld too long your work piece will heat up in that area and could become warped or compromised, so it's best to do a little welding in one spot, move to another, and then come back to finish up what's left in between.

What are the right settings?

If you are experiencing holes in your workpiece than your power is turned up too high and you are melting through your welds.

If your welds are forming in spurts your wire speed or power settings are too low. The gun is feeding a bunch of wire out of the tip, it's then making contact, and then melting and splattering without forming a proper weld.

You'll know when you have settings right because your welds will start looking nice and smooth. You can also tell a fair amount about the quality of the weld by the way it sounds. You want to hear continuous sparking, almost like a bumble bee on steroids.

Step 6: Welding Metal Together

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Once you've got your method tested out a bit on some scrap, it's time to do the actual weld. In this photo I am doing just a simple butt weld on some square stock. We've already ground down the edges of the surfaces that are going to be welded so that the seem where they meet makes a small "v".

We are basically just taking the welder and making our sewing motion across the top of the seem. It's ideal to weld from the bottom of the stock up to the top, pushing the weld forward with the tip of the gun, however that isn't always comfortable or a good way to start learning. In the beginning it's perfectly fine to weld in whatever direction/position that is comfortable and that works for you.

Once we finished welding the pipe we were left with a big bump where the filler came in. You can leave that if you like, or you can grind it flat depending on what you are using the metal for. Once we ground it down we found once side where the weld didn't penetrate properly. (See photo 3.) That means that we need to have more power and more wire to fill in the weld. We went back and redid the weld so that it was properly joined.

Step 7: Grind Down the Weld

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If your weld isn't on a piece of metal that will show, or if you don't care about how the weld looks, then you are done with your weld. However, if the weld is showing or you are welding something that you want to look nice then you will most likely want to grind down your weld and smooth it out.

Slap a grinding wheel onto an angle grinder and get started grinding on the weld. The neater your weld was the less grinding you will have to do, and after you have spent a whole day grinding, you will see why it's worth it to keep your welds neat in the first place. If you use a ton of wire and made a mess of things it's ok, it just means that you might be grinding for a while. If you had a neat simple weld though, then it shouldn't take too long to clean things up.

Be careful as you approach the surface of the original stock. You don't want to grind through your nice new weld or gouge out a piece of the metal. Move the angle grinder around like you would a sander so as not to heat up, or grind away any one spot of the metal too much. If you see the metal get a blue tinge to it you are either pushing too hard with the grinder or not moving the grinding wheel around enough. This is can happen especially easily while grinding thing sheets of metal.

Grinding welds can take a while to do depending on how much you have welded and can be a tedious process - take breaks while grinding and stay hydrated. (Grinding rooms in shops or studios tend to heat up, especially if you are wearing leathers). Wear a full face mask when grinding, a mask or respirator, and ear protection. Make sure that all your clothing is neatly tucked in and that you don't have anything hanging down from your body that could get caught in the grinder - it spins fast and it can suck you in!

When you are done your piece of metal might look something like the one in the second photo pictured below. (Or maybe better as this was done by a few Instructables Interns at the beginning of the summer during their first welding experience.)

Step 8: Common Problems

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It can take a good amount of practice to start welding reliably every time, so don't worry if you have some problems when you first stop. Some common problems are:

  • No or not enough shielding gas from the gun is surrounding the weld. You can tell when this happens because the weld will start splattering little balls of metal, and will turn nasty colors of brown and green. Turn up the pressure on the gas and see if that helps.
  • Weld is not penetrating. This is easy to tell as your weld will be weak and won't be fully joining your two piece of metal.
  • Weld burns a while right through your material. This is caused by welding with too much power. Simply turn down your voltage and it should go away.
  • Too much metal in your weld pool or the weld is globy like oatmeal. This is caused by too much wire coming out of the gun and can be fixed by slowing down your wire speed.
  • Welding gun spits and does not maintain a constant weld. This could be caused because the gun is too far from the weld. You want to hold the tip of the gun about 1/4" to 1/2" away from the weld.

Step 9: Wire Fuses to Tip/Change the Tip

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Sometimes if you are welding too close to your material or you are building up too much heat the tip of the wire can actually weld itself onto the tip of your welding gun. This looks like a little blob of metal at the tip of your gun and you'll know when you have this problem because the wire won't come out of the gun anymore. Fixing this is pretty simple if you just pull on the blob with a set of pliers. See photos 1 and 2 for visuals.

If you really scorch the tip of your gun and fuse the hole closed with metal then you need to turn the welder off and replace the tip. Follow the steps and the overly detailed photo series below to see how it's done. (It's digital so I tend to take too many pictures).

1. (Photo 3) - The tip is fused closed.

2. (Photo 4) - Unscrew the welding shield cup.

3. (Photo 5) - Unscrew the bad welding tip.

4. (Photo 6) - Slide a new tip into place.

5. (Photo 7) - Screw the new tip on.

6. (Photo 8) - Replace the welding cup.

7. (Photo 9) - It's now good as new.

Step 10: Replace Wire Feed to Gun

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Sometimes the wire gets kinked and won't advance through the hose or the gun even when the tip is clear and open. Take a look inside of your welder. Check out the spool and the rollers as sometimes the wire can become kinked in there and need to be re-fed through the hose and the gun before it will work again. If this is the case, follow these steps:

1. (Photo 1) - Unplug the unit.

2. (Photo 2) - Find the kink or jam in the spool.

3. (Photo 3) - Cut the wire with a set of pliers or wire cutters.

4. (Photo 4) - Take the pliers and pull out all of the wire from the hose through the tip of the gun.

5. (Photo 5) - Keep pulling, it's long.

6. (Photo 6) - Unkink the wire and feed it back into the rollers. To do this on some machines you have to release the tension spring holding the rollers down tight on the wires. The tension bolt is pictured below. It's the spring with the wing nut on it in it's horizontal position (disengaged).

7. (Photo 7) - Check to make sure the wire is properly seated between the rollers.

8. (Photo 8) - Re-seat the tension bolt.

9. (Photo 9) - Turn on the machine and depress the trigger. Hold it down for a while until the wire comes out of the tip of the gun. This can take 30 seconds or so if your hoses are long.

Step 11: Other Resources

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Some of the information in this Instructable was taken from an online Mig Welding Tutorial from the UK. A bunch more of the info was gathered from my personal experience and from an Instructables Intern welding workshop that we held at the beginning of the summer.

For further welding resources, you could consider buying a book about welding, reading a knowledge article from Lincoln Electric, checking out the Miller MIG Tutorial or, downloading this beefy MIG Welding PDF.

I am sure that the Instructables community can come up with some other great welding resources so just add them as comments and I will amend this list as necessary.

Check out the other how to weld instructable by stasterisk to learn about MIG welding's big brother - TIG welding.

Happy welding!


Sberlins (author)2017-11-06

Very good guide! Thank You for sharing.

danmst3k (author)2009-10-09

Great instructable! I just got a welder from Harbor Freight. It's a 90amp wirefeed flux core for $63 after using a 20% off coupon along with a sidewalk sale(reg $149.99 on sale for $79)!!! But, anyway, I haven't tried it yet and still need to learn a few more things. One question I have is what happens if your bare skin makes contact with the welding table or the piece of metal you are welding. Can you get a shock from that? I know, it's probably a dump question but I haven't seen it addresed anywhere. Thanks.

KristianR14 (author)danmst3k2017-07-19


I never thought about it to get shocked and I often welded with a friend who was holding one of the pieces to be weld. Never heard about getting an electrical shock during welding ....

CPUDOCTHE1. (author)danmst3k2017-07-11

I have NEVER been shocked by a welder unless I make contact with the ground AND the electrode , wire, or tungsten. You can weld electrode positive or negative and not get shocked by the ground clamp or anything attached to it.

dla888 (author)danmst3k2010-01-13

Yep, I'd be willing to bet that you would be on the recieving end of a large and painfull shock. Basically MIG welding is a big electrical circuit and if the table is metal it will conduct electricity.

Mr.Sticky (author)dla8882010-02-07

Any welding is a big electrical circuit.  However, remember the basic rule of follows the shortest path to the ground.  And in welding, once it has a circuit established, it will follow it.  So if you do accidently touch the table that the metal is on, no, you most likely won't get a shock.   But I wouldn't try it!!  

itsmescotty (author)Mr.Sticky2017-07-11

NOT shortest, path of least resistance. Hell, I used to sit on submarine hulls and weld on them. The human body is a few hundred thousand ohms and the steel is near zero.

oceankayaker11 (author)dla8882010-02-07

Theoretically, no you wont be shocked. The electrical current is looking for the easiest way to the ground (I know, an easy way to explain how electrons act) but since your table or material being welded is being grounded through the ground clamp, through the welder, and through the wiring in your house to the grounding rod installed outside it will pick to go through the ground clamp and not you, assuming you dont wear a wetsuit filled with water and golden boots all whole standing on a metal table directly grounded. Long as you aren't that dumb you should be fine.

jyoci (author)2017-07-14

Good article.
Just a notice: psi or cubic feet per second or so aren't official international mesures.

Lorax98 (author)2010-04-09

The "shield" gas is exactly that, a shield. It prevents gas molecules from the atmosphere from reacting with your molten metal. The term MIG stands for Metal Inert Gas; Inert- as in nonreactive. It is actually the Carbon Dioxide in the atmosphere that is the real problem.

CPUDOCTHE1. (author)Lorax982017-07-11

NO, it is the OXYGEN. You can MIG weld with pure CO2. It gives better penetration than Ar or CO2/Ar.

itsmescotty (author)Lorax982017-07-11

Not correct. It's the oxygen that causes oxidation, the hydrogen that causes cracking and considering there is an argon/CO2 mix What the hell are you talking about?

brandon_a_boyer (author)Lorax982011-05-02

Sorry, Incorrect, it's the oxygen that is the real problem, CO2 is commonly used as a shielding gas.

godfreyandthandi (author)2009-08-22

i never wear gloves when welding i have never been burned once!

So, you've only welded twice? and it was a horizontal weld?

amoroso82 (author)2010-04-08

I recently found the need to get a MIG welder to do some repairs around here, since I have never used this meathod of welding before I got a book and began to read up on this. Now I saw this article in Instructables that has raised some questions.
 I purchaced an 120 amp welder from Harbor freight as I am not going to use this machine to do structural welding I got their middle one. ( there is one cheaper and one more expensive) I guess since I was buying crap I didnt want cheap crap.  Any way they said that there is no need to use an external source of inert gas even though the machine is set up for it, I was told that I could use wire that has flux or some material that produced inert Gas while you are welding. Is that an inferior way to weld?and do I need to get this bottle?
 The reason I asked this is because I have read almost through this whole article and the writer has only mentioned the flux core wire once. I got this thing because it was less expensive than a buzz box and I can weld thin metals easier but if I have to shell out more spondulix for gas bottles and gauges the price can go up dramaticly.

Sexy_Beast (author)amoroso822010-10-14

If you use flux core wire, there is no need for shielding gas. However with flux core wire, you can only weld mild steel. Flux core wire can be used on any MIG welder, you just have to have the polatity reversed than you would for if you were welding with shielding gas. (usually easily done by flipping a switch or reversing the gound wire and the drive motor wire on the machine. think car battery terminals. your manual should cover how to do this on your machine). The advantage of flux core welding is that you get deeper penetration with the same amount of current than you would with your machine set up to use shielding gas with that same amount of power. Also, flux core is better for use outdoors where there may be a breeze that would otherwise blow your shielding gas away. In flux core welding, the flux is inside the wire, and as the wire burns, the flux creates a shield around the molten metal, protecting it from oxygen, which would otherwise contaminate the weld and make it weak. The disadvatage however is that it produces a lot of spatter, and the welds don't look as pretty either. BUT it does do a better job of penetrating rust/paint better than it would if you were using an external shielding gas. (although, you're really supposed to remove any rust/paint first). You do not have to buy a bottle of shielding gas or regulator if you weld with flux core only, but I'll tell you right now, it's a LOT easier to get good looking welds if you use shielding gas. As for what gas to use, for aluminum you have to use 100% argon. For mild steel, you can use CO2, Argon, or a 75%/25% Argon/ CO2 mixture. 100% Argon will give you the best looking weld, CO2 will give you the best penetration if you're welding something thick, but generally what is recommended is is the CO2/Argon mix, since overall it combines the best of both worlds. However it is slightly more expensive the the other two. As long as you want to weld mild steel, you don't HAVE to use shielding gas, so long as you use flux core wire. But if you want to weld stainless, or aluminium, or get really clean welds on steel, you'll need gas. On a side note, if you DO weld aluminum, you'll have to get a teflon liner for your welding wire hose. Otherwise, since the aluminum welding wire is so soft, it will get bent or caught up in the hose causing what's called "birds nesting". hope I answered all of your MIG questins. Happy welding, bro!

Wrong. You can indeed weld stainless steel with flux cored wire.

also switching to U-groove drive rollers will help feed aluminim wire more effectively.

And cast iron. It's all in the wire you use. Geez, you can even weld cast with 70 series wire tho cast is better or a nickle content wire.

migallday (author)Sexy_Beast2012-05-16

LIAR ALWAYS USE A GAS. i weld mild steel high heat with flux core all day and i use argon. without it i couldnt weld.

itsmescotty (author)migallday2017-07-11

Congratulations, I'm happy you use argon with your flux core wire.

Too sad tho that without it you can't weld. You have a problem and couldn't work for me. ONLY reason to use flux core wire is in a drafty area.

Technically speaking alot of Flux cored wires produce better quality welds than solid wires do. They do have drastically different techniques though.

flux cored wires require longer electrode stick outs and faster travel speeds. Also, you'll need to use a slight drag angle instead of pushing.

Rollin 007 (author)amoroso822010-11-04

Wow, I did the same thing you had done and I am too getting on line and trying to find out a little info on my "220 VAC Dual MIG Welder". Luckily, I have a current 12 yr. experienced welder in the family. Yes, I could ask him any ?'s I might have and see if he could teach me the basics of welding but I couldn't ask him to do all of that if I haven't done any work on my own. So here I am, trying to find a little more detailed info on welding. I see you posted your response back in April, have you gotten anywhere since then? I'm sure you've gotten further than me, have you learned any tricks to the trade? Maybe, we can help each other out or maybe you could possibly find the time to help me out on where to go from here? I'm am eager to learn and would be most appreciative of any help. Thanks


ncblu (author)2009-01-05

i weld for a living. folks before you spend large amounts of money on a welder, make sure you are willing to spend the time practicing, thats the most important thing, practice, practice, practice. start running straight passes, no weaving or sewing or circling. when running a bead remember - where you point the tip is where the weld will be. if you're using gas, watch for porosity because you pulled the tip back too far and contaminated the weld. dont grind your welds - it's a bad habit, even if your welds arent pretty, they will be in time. speed is very important, constant steady speed. the welders you buy at harbor freight or walmart are fine for tack welding, but i wouldnt put it to use on a trailer or something that could have bad results if a weld cracks. if you run without gas you will get lots of spatter, even with anti spatter dip. prep is the most important, make sure your metal is clean and bevels should be between 25% and 50%. when making t-welds or perpendicular welds remember the metal will contract TOWARD the weld bead, not away from it ( i know this is contrary to popular belief and highschool science but it will happen ). never weld in a down direction, never drag the bead like you would in stick welding, always be pushing the puddle in the direction you want to go. most of all practice, practice, practice

ncblu (author)ncblu2009-01-05

one more thing, if you want to make a living as a welder, do not weave or circle or sew - you likely wont make it through to morning coffee break. also be prepared to weld out-of-position, this is welding on any surface that isnt sitting flat on a table ( which actually is harder to do properly than it sounds ). you might be welding upside down with hot metal dropping in your shirt.

itsmescotty (author)ncblu2017-07-11

Are we talking spatter or gobs of metal falling from your weldment? When I weld overhead I use stick, tig or pulsed are. Don't like short arc or spray for overhead AND GOD made leathers for overhead welding and gouging.

GabrielleC1 (author)ncblu2014-10-15

thanks for all the excellent tips!! A few questions…is it possible to find a 110v MIG that actually penetrates? I am a home/garage hobbyist looking to weld materials averaging around no more than 3/16-1/4" thick, mostly for art projects, making lights etc…I have more experience with arc welding on thicker materials. I have heard that you can't really weld with 110 but I see a lot of machines out there… I am also considering going for a lincoln 225, I see a lot of them on CL, but I am not sure if that will be more power than I need. What do you suggest?

Beausejour (author)ncblu2009-03-14

HI There Can you tell me how close i should hold the tip from my work.

joshr123 (author)Beausejour2013-11-12

I usually Lay the tip on the metal and angle it.

For solid wire you want the wire to stick out about 1/4 to 1/2 inch, for flux cored wire you want a 1 inch stickout.

Spudmuffon (author)ncblu2013-03-05

I agree on all points except for the grinding of the welds in my line of work (chassis fabrication) grinding the welds to make a flat billet style appearance is mandatory as long as the weld was properly prepped and is not over finished there will be no ill effects.

headache2000 (author)ncblu2009-12-31

Thanks for that "pushing" the weld info  I've been trying  to drag the weld. Not working very well either.  Probably not my only problem however. As I mentioned before all I've ever done is stick welding.

ironandwine (author)ncblu2009-01-08

So what brand of mig welder would you recommend looking at? I'm a carpenter but my next job has a good amount of steel involved.

stallsworth (author)ironandwine2009-03-13


ncblu (author)stallsworth2009-03-13

2nd that - they're worth every bit you pay for them

ncblu (author)ironandwine2009-01-08

its kind of hard to tell you exactly what type. I use miller welders at work because they are industrial grade and allow for mig/tig/stickwelding in one unit. they use gas shielding and are 3 phase units. the best way to decide is to try this link at miller under the product menu, you'll see smart select, they ask you a bunch of questions to help you decide. once you found the type and specifics that will give you an idea if you want to try another brand. it all depends on the type of metal your welding, the size of metal, available supply voltage, will you want to use gas or gasless and the size wire you want 0.16 or 0.32 is best. the units at walmart and home depot are ok and they can be used in either gas or gasless mode but using gas shielding is always better, if you go gasless you will use flux-core wire and it doesn't work very well on thicker metal and it spatters alot. hobart makes a pretty decent portable welder but they're pricey. lincoln makes good welders also. as for helmets, what do you want, automatic or standard. i would go to a welding shop for a helmet, the ones at the hardware stores that you can get for 99 bucks are only going to give you sore eyes after a little while, they just aren't that good. i use both kinds, automatic for short welding and my standard helmet if I'm gonna be running passes for the next few hours continuously ( stay away from gold plated lenses in your manual helmet, if the gold gets scratched the UV will pas right through and burn your retina's) get a good pair of gloves that aren't tight on your fingers. while you're at it pick up a good chipping hammer and wire brush from a weld shop- the ones at the hardware store wont last and grab a container of nozzle dip, some spare tips an extra spool of wire and a pair of welpers ( pliers) i know it sounds like alot but it really helps make the welding go smoother and makes for cleaner better welds in the end

hope this helps

ColinB4 (author)2014-12-29

I have written so many articles on welding procedures
but after reading this article felt like never knew anything about MIG welding.
Great job author.

itsmescotty (author)ColinB42017-07-11

Now, that's just a sad comment.

I only write about what I KNOW and anything else is speculative.

itsmescotty (author)2017-07-11

MIG welding can only be used on thin to medium thick metals.

Interesting that you think 3" and 4" are considered medium thick metal.

Don't know about now but the Los Angeles class submarines had a lot of hull sections and missile tubes MIG welded.

CPUDOCTHE1. (author)2017-07-10

OXYGEN IS NOT FLAMABLE. It ONLY supports combustion.

Tomas Jansen (author)2017-02-27

This has been so helpful to me. I'm a freshmen in high school and I take welding class, I have gotten past my other 1st year class mates and I moved onto mig welding and this has helped me greatly.

JanieK (author)2014-09-02

I'm struggling to choose my first welding equipment. Been searching the web for reviews etc. There's plenty of pages like but I'm not sure if a $300-$500 is good enough for my household needs

JanieK (author)JanieK2017-01-04

Just an update. After doing some research I decided to go with the Hobart Handler 140 MIG welder. That must have been about two years ago. I'm really happy with the choice, for the 115V the welds are nice and strong. It was super easy for starting out too. Now, I also own a TIG welder that I use to make some bicycle frames and artsy stuff. Keep welding!

rogekrimsky (author)JanieK2017-02-11

Don't know why all reviews tend to eliminate equipment from Harbor Freight. Not all of their stuff is tops, but most will be more than adequate for most users. Just got through welding with a $90 wire fed unit. First time through results were not good. Noticed a High Power switch, moved it to that, increased the wire feed speed, and surprised myself at the results. This was only my second time out welding, so I was very pleased but wanted to confirm that the power was the reason for the great results. Found this article, thanks to NoahW. but had to comment on getting great results from a comparable welder at a way lesser price.

wintermute22 (author)2016-02-16

Absolutely great instructable, especially for the beginner - thanks a lot! But I have possibly the most idiotic question of all that was not answered. I had a stick welding crash course some two years or so ago and they taught us to calculate the space between the electrode and the workpiece. It' such a f**k. Now, in MIG-Welding DOES THE WIRE TOUCH THE WORKPIECE or do you have to maintain a space just like in Stick welding? I know it's a stupid question... Thanks everybody in advance.

CPUDOCTHE1. (author)wintermute222016-11-04

You must maintain the correct and uniform distance from the nozzle to the work. You adjust the wire speed to keep the wire from hitting the work too hard.

nwlaurie (author)wintermute222016-10-17

The wire touches the workpiece in MIG welding

CPUDOCTHE1. (author)2016-11-04

Oxygen is NOT combustable. You need to open ALL valves fully except for fuel valves (acetylene and propane) because some valves do not seal around the stem when they are partially open.

ConraM1075 (author)2016-10-31

Good information on how to weld

cortchops (author)2016-10-10

"A grinder and paint, makes me the welder i 'aint"

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