MIG vs. TIG fundamentals: What you need to know

By Carl Heideman
Nov 19, 2022 | Welding, MIG, Tig | Posted in Shop Work , Features | From the June 2011 issue | Never miss an article

Photography by Carl Heideman

We’ve spent a lot of time discussing welding skills and technique in this magazine, but maybe it’s time to back up and start at the beginning: How do you decide what kind of welder to use in the first place? 

Sure, the skills and techniques we’ve covered apply to all types of welding, but we’ve generally assumed that our readers are most familiar with MIG welding. The MIG approach has become nearly ubiquitous thanks to the availability of relatively inexpensive, high-quality machines from numerous manufacturers. 

However, more and more members of the grassroots community are getting their hands on TIG welders. A new wave of lower-cost equipment and a bevy of craigslist ads hawking used machines have given enthusiasts another affordable way to weld.

If you sit around and bench race welders with your friends, one of them will quickly proclaim that TIG is better than MIG. Is that true? Well, let us put forth this proposition: As with most of life’s big questions, the answer is, “It depends.” The two types of welders operate differently, and each one has its advantages and disadvantages. We’ll let you make the final call based on your needs.

Hard or Soft?

When it comes to home welding, many people gravitate toward MIG units. A MIG welder uses a consumable wire that the machine feeds automatically. As a result, learning to use one is relatively easy.

Let’s get right to it with some quick definitions. MIG stands for metal inert gas, while TIG stands for tungsten inert gas. Further, the M and T give us important information about each method’s heat source. Let’s dig into that subject next.

In the case of MIG welding, the heat source is the consumable wire. In the case of MIG welding, the heat source is the consumable wire. The wire and its arc heat the surrounding (base) metal, melting it together into a fused and welded joint.

With TIG welding, the heat source is the tungsten-tipped torch. The arc from the torch heats the surrounding metal, and then the consumable rod is melted in, forming the fused and welded joint. 

Doesn’t sound like these two welders are all that different, right? Turns out they really are: Where the heat comes from and, more importantly, where the heat goes, can significantly affect weld quality. 

With MIG welding, the heat starts at the weld joint and moves to the base metal. With TIG welding, the heat starts at the base metal and moves to the weld joint. 

Another big factor is how the weld cools. A MIG weld cools much faster than a TIG weld. That’s because the base metal surrounding it serves as a heat sink that quickly sucks the heat from the MIG joint. A TIG joint, on the other hand, cools relatively slowly because the base metal is already very hot—and that means no heat sink effect.

A couple parts of this story will prompt the engineers to chime in with angry emails about our grassroots explanations of deeper science. Here’s their first opportunity to do so: Time to discuss the strength differences between these two types of welds. 

Most people understand that heat treating metal usually involves heating it and then cooling it, often rapidly. When metal is heat treated, it often becomes harder, which implies—and means—more strength. This strength is often measured as tensile strength.

While high tensile strength is the real deal, it does have a couple side effects: increased brittleness and reduced malleability. Harder metal truly is stronger—but it’s only stronger until it breaks. Plus, sometimes brittleness is a bigger problem than low tensile strength.

Let’s apply this to how MIG and TIG weld joints cool. It turns out that a MIG weld joint becomes very hard and very brittle due to its fast cooling. Conversely, a TIG joint’s slower cooling leaves it softer and more malleable. 

Clean or Dirty?

A TIG unit doesn’t take up much more space in the shop, but the welding process is a bit more involved. Prices for TIG machines have dropped to the point where more hobbyists are checking them out.

There’s more to these two types of welds than their strength and malleability. A large factor in the quality of a weld is the joint’s cleanliness, and this is another area where MIG and TIG welding are quite different. 

Most people understand that the inert gas used in MIG and TIG welding plays a huge part in keeping the joint clean. However, they’re overlooking the role of heat. 

Both machines circulate inert gas—usually argon, CO2 or a mix of both—around the weld joint to keep it from becoming contaminated with dirty ambient air. This process works very well, but the gas shouldn’t get all the credit. It turns out that heat can really help clean a weld joint, too, and that’s where MIG offers an advantage.

Think about a self-cleaning oven. It works by running at a very high temperature, burning the crud off the racks and interior surfaces. The heat concentrated at the MIG joint has a similar effect on the base metal, improving the quality of the weld. 

You’ll remember that we strongly advocate cleaning weld joints thoroughly before welding. In fact, “You can’t weld dirt” is one of our welding mantras. 

While buying a MIG welder won’t get you out of cleaning duties, sometimes it’s difficult to remove all of the grime. In these cases, MIG welding is your best bet. Maybe TIG isn’t always better than MIG after all. See how it depends? 

Steel or Aluminum?

MIG and TIG welds feature different levels of hardness—technically called malleability. The piece on the left was TIG welded together before being passed through a planishing hammer at 10,000 blows per minute for about 2 minutes; the malleable weld was hammered nearly flat. The piece on the right was MIG welded together and also spent about 2 minutes in the planishing hammer. The hammer couldn’t get very far since the weld was so much harder and therefore less malleable. (It’s hard to see in the photo, but the brittle weld also cracked during the hammering. Hard can be good, but brittle can be problematic.)

Now let’s go a little deeper into welding operation and theory. Engineers, here’s your second chance to scoff at our generalizations or grab your pitchforks.

We’ve talked about how heat affects the weld joint, and we’ve talked about where the heat is applied—at the joint or at the surrounding metal. It turns out that the polarity of the welder also affects where the heat ends up.

When welding steel, both MIG and TIG machines use DC current. There tends to be more heat on the positive side of an electrical circuit, and a MIG welder’s torch and wire typically handle that end of things; its ground wire is usually set to negative. This setup makes the MIG weld joint hotter and the base metal cooler. 

A TIG welder’s polarity is the opposite. Its torch is set to negative and the ground is set to positive, which means heat travels into the base metal. Here’s the rule of thumb: With a MIG weld, two-thirds of the heat is in the weld joint and one-third is in the base metal. With a TIG weld, the inverse is true: Two-thirds of the heat is in the base metal and one-third is in the weld joint.

Let’s look at the TIG welding process a bit more. It uses DC current for steel, but it switches to AC current to tackle aluminum. Why the special treatment? Because aluminum is much more sensitive to contamination than steel. It’s also much more likely to crack. 

Aluminum requires a welding process that can handle dirt well (like MIG) and create a less brittle weld joint (like TIG). TIG welding with AC current offers a set of compromises that make it more suitable for the job. 

Let’s dive even deeper into the process. An AC circuit reverses polarity 60 times per second on common household or industrial current sources. They don’t call it alternating current for nothing. 

With TIG, the ideal setup for welding has the torch negatively charged and the base metal positively charged. The ideal setup for cleaning is when the polarity is reversed. Since AC current causes the polarity to switch constantly and rapidly, a single TIG welder can handle both the welding and cleaning processes. The result: a quality weld joint. 

As a side note, more advanced TIG welders allow the user to adjust the AC process: You can lengthen the negative grounding wavelength to boost the cleaning capabilities, or lengthen the positive grounding wavelength for faster and more powerful welding. 

So, what about welding aluminum with MIG? While it is becoming more common and practical to use specially equipped MIG welders for aluminum, TIG still tends to hold the advantage and is more flexible in most cases. This specific topic really warrants its own story, so keep your eyes peeled for that in a future GRM.

Simple or Complex?

MIG and TIG machines both require the operator to use different techniques, but MIG welding is a bit easier. Once the knobs on the welder are properly set, welding with a MIG can be a one-handed affair. The on-off switch is located on the torch itself, and the welder automatically feeds the wire. (We recommend having two hands on the torch for additional control, though.)

If MIG welding is like throwing a ball, TIG welding is like juggling three of them. Guess which one is more difficult to master.

MIG welding can be a one-handed, point-and-shoot operation. You set the welder, pull the trigger, and off you go. With TIG welding, you’ve got to handle three different operations at once. One hand holds the torch and the other hand feeds the rod. Meanwhile, your foot is on the current pedal, and the harder you push, the more current (heat) you put into the weld.

As with juggling, these three factors must be in sync with one another or you’ll drop the ball and mess up the weld. So, this is another difference between MIG and TIG: It takes more time and practice to become proficient at TIG welding. 

While that may make TIG seem less appealing, its complexity is actually a benefit. Good welding is about good control, and with a TIG welder you can dynamically control a lot more of the welding process. 

With MIG, you set your current and wire speed before welding. After that, you don’t have to worry about them—but you can’t adjust them while you weld, either. TIG welding, on the other hand, allows you to make adjustments on the fly. If you need a little more heat, just press the pedal a little further. If you need a little less, back off a bit. More filler? Feed the rod faster. And so on. 

TIG welders offer a level of flexibility that can greatly improve the quality of a weld. (Note: There are high-end MIG welders on the market that let you adjust these parameters as you go, but they’re generally out of reach for most enthusiasts.)

Another practical difference between these two welders involves prep work: MIG welding is more forgiving when it comes to the fit-up of the joint. Since TIG welding requires heating the base metal and then melting the rod, the base metal components need to fit together very tightly so they can be evenly heated and thus evenly melt the rod. If there’s an air gap, the weld will often fail. On the other hand, since a MIG welder’s heat source is the filler wire, it’s not only more forgiving to the base metal, but it can also fill air gaps to some extent. 

Fast or Slow?

TIG welding is a bit more involved: One hand holds the torch, the other hand feeds the rod, and a foot controls the current. While harder to learn, the TIG process does offer the advantage of more dynamic control during welding—heat and speed can be easily adjusted on the fly.

Whether you’re welding on the job or at home, time is usually money. MIG and TIG units operate at different paces, both before and during the welding process. 

Assuming you have a higher-end MIG welder that can handle aluminum, converting it from its steel setting requires some work. Typically this means changing the shielding gas, the wire, the welder polarity (often with some disassembly of the welder) and even the liner or the whole welding torch assembly. Setting up a TIG welder for aluminum is usually as easy as flipping a switch from DC to AC and using a different rod.

However, MIG welding is typically a speedier operation than TIG welding. Since the wire feeds automatically and the heat gets in the weld joint faster, MIG welding is generally a timesaver. 

We usually figure that MIG welding is about two to three times faster—that is, it will take two to three times as long to lay a 12-inch bead with TIG than MIG. That extra time may not matter to everyone, but especially in production environments, MIG can offer a distinct advantage.

See, It Really Does Depend

Finally, there’s the cosmetic factor. Even the staunchest defenders of metal inert gas will admit that TIG welds look better than MIG welds. Sure, MIG welds can look nice, but TIG welds can approach art. That stacked-coins look produced by a well-executed TIG weld is what most welders are after, especially on exposed welds. Compared to the lumpier and less graceful look of the MIG weld, TIG work generally wins any beauty contest.

So, is TIG better than MIG? It’s certainly got some advantages, but so does MIG. We hate to say it, but the answer really depends. At least now you have the information to make the decision for yourself. 

Which is the best for us? How’s this for an answer: We’ve got both types in our shop, and we pick the best one for the operation at hand.

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Furious_E GRM+ Memberand Reader
9/17/15 3:57 p.m.

In reply to Carl Heideman:

No that I'm an expert by any means (far from it), but here's my $.02:

As it pertains to which of the two is easier to learn on, it seems the common advice is start with MIG if you've never welded before. I had tried both MIG and stick on a handful of occasions in high school shop class before really learning to weld on the school's SAE Formula Hybrid team in college doing TIG.

Starting out with MIG, I feel like the M.O. is basically pull trigger, keep tip in general vicinity of joint. I felt that TIG allowed me to better see how I was manipulating the weld pool, I could control it better due to the slower pace, and I got a better feel for amperages and "feed rates" through being able to manipulate both on the fly. I actually got halfway decent at TIG for a few years and chose that process exclusively even for personal projects, even though I had access to a MIG on campus as well.

ncjay Dork
9/17/15 4:30 p.m.

The MIG gets used for mild steel only. TIG gets used for anything else, or anything that needs to be real pretty. I've seen some awesome MIG welds in aluminum, but it's a pain changing gas bottles and wire, etc. Hadn't really given it much thought until now, but you can weld everything with a good TIG machine, but the MIG machine is fairly limited.

Trans_Maro PowerDork
9/17/15 4:33 p.m.

You can MIG weld aluminum and stainless, it's not limited to mild steel only.

The advantage is that MIG is pretty much a "hot metal glue gun" thanks to the auto-set welders you can buy now.

Heck, even Mikey from OCC can use a mig welder.

Hungary Bill
Hungary Bill GRM+ Memberand SuperDork
9/17/15 6:17 p.m.

Having never "really" welded, I thought I wanted a MIG. I went to Mezzanine's house and realized I really wanted a TIG.

The potential is there with a TIG, even if I'm not quite "there" yet.

wheelsmithy GRM+ Memberand HalfDork
9/17/15 6:30 p.m.

My feelings: First a MIG. for tacking, etc. Then a TIG to make beautiful welds with less warping. Stick is valuable as a baby step towards MIG, Gas the same if TIG is the goal.

I guess the catch for Grassroots folks is tacking. Can you hold those header pieces together in the engine bay, and with TIG? Best have both.

motomoron SuperDork
9/17/15 10:31 p.m.

TIG is for the race car and things in the machine shop.

MIG is for trailers and cars w/ VIN plates.

The process that's closest to TIG from a learning standpoint is gas welding. Anyone w/ tanks and a torch would do well to get a book and learn how. Every tube fuselage airplane from the beginning of flight to the 60s was most likely gas welded.

kb58 Dork
9/17/15 10:55 p.m.

TIG: artist's brush, precise, fine point, slow, clean

MIG: house painting brush, fast, not so precise, a bit messy

Kenny_McCormic UltimaDork
9/17/15 11:18 p.m.

In reply to motomoron:

Pretty much anything that can be TIGed, can be, and historically has been, OA welded. I think the practice really only died out because TIG works out cheaper and safer to operate at any sort of production/shop scale, and probably home as well.

Kreb GRM+ Memberand UltraDork
9/17/15 11:20 p.m.

My feelings echo most of what's been said. One thing is that I've never gotten comfortable with the hand amperage control for TIG welders. I much prefer the foot pedal, but when you're climbing all over something, often the pedal doesn't work.

Trans_Maro PowerDork
9/17/15 11:43 p.m.

Stick welding is still very valid and used a lot, just not in applications we're likely to be using.

9/18/15 5:50 a.m.

I have a MIG and a TIG. TIG used to be the only welder in the shop cause I thought it was more cooler than MIG. Once I bought the Lincoln MIG the TIG has gathered dust and I have done a lot more fabricating.

If you can only have one rig, and old cars are your game, it is possible to get by with only the MIG. It will be quite difficult to get all panels and parts clean enough to TIG. (backside of a long quarter panel seam for example, assuming you CAN get at the back) Then we can talk about out of position welding and working a foot pedal.

If you are running a shop or paying for one's time, a TIG welded quarter panel seam is going to take 3 times or more to than the MIG equivalent.

With TIG, you are constantly sharpening and changing out tungstens either because you dipped the tip or need a different diameter. This will drive you nuts when you start out.

They both weld aluminum but if doing thin sheet, the TIG is the only real option.

Don't let anyone tell you that you can't metal finish MIG welds.

TIG wont tolerate weld-thru primers. This means that lap joins or spot welded joins will be more rust prone.

Neat trick with TIG is you can do a spot weld without drilling the top panel.

TIG is kind of like the parachuting or base jumping of the welding world, very rewarding when done right, while MIG is more like skiing.

fasted58 UltimaDork
9/18/15 7:25 a.m.

Synchrowave 300 and a Millermatic 185. Before I bought the MIG I would TIG everything. I bought the TIG machine before learning. A retired T&D welder taught me the basics, then practice, practice, practice. I bought the MIG new w/ absolutely no experience and learned on my own in my shop. Now the MIG sees 95+% of the work. E36 M3, I don't even wanna stick weld anymore. I still like to play w/ gas welding once in a while, very similar to TIG as said above.

From a learning standpoint I like to tell folks to start w/ a good MIG machine before stick. I've seen newbies get turned off by stick welding w/ the splatter, discipline and fumes. Well, I did catch my pants on fire back in the day. MIG is the Easy Button of welding, builds confidence faster w/ practice and then they're hooked.

Once hooked, TIG is a natural progression to learn if you're really into it.

WilD HalfDork
9/18/15 8:21 a.m.

I have learned a lot from the article and this thread... thank you all.

jimbbski Dork
9/18/15 9:03 a.m.

My father was a pipefitter and was an expert stick welder as that was what you had to use out in the field. I never got very good at it. I later purchased a MIG welder and used it to fab up many of my car projects. I later purchased a TIG and now will use it 90% of the time for the type of fab projects I do. If doing a roll cage I use MIG but will use TIG in a few spots that are hard to get to. The nature of MIG is that you are constantly adding filler when ever the trigger is pulled and getting a good weld in these tight places is difficult. The control TIG provides is what I like.

I currently own a newer Lincoln 180 Dual Voltage MIG and a Lincoln Econo TIG. Both are use on a regular basis. I bought the new MIG as I got a good deal and it's much more portable then the old MIG I had and as well as the TIG. Also it operates on 110V or 220V so I can take it to a friends house without worrying if he has 220V in his garage.

Jamey_from_Legal Reader
9/18/15 10:13 a.m.

If more people could weld steel and solder tube, I think they would enjoy their hobbies more. It's really useful.

I think there are just so many mental barriers, that many people never attempt it.

A decent MIG machine with gas (I entered the fray with a 180 amp Lincoln wired to 220) let me get through a lot of the frustrating things I needed to learn. Like fit-up, clamping, burn-through, torch angles, vision and position. If I had started with TIG, I'm not sure I would have stuck with it.

OTOH, if I had started with an inexpensive flux MIG, I'm not sure -- that might have frustrated me enough to put me off.

Plus if you look around, there are some videos that will show how to make really good, good-looking MIG welds.

I encourage anybody who's thinking about taking the step into welding, to just go get that MIG w/ gas and get started.

Gasoline SuperDork
9/18/15 11:33 a.m.

I will add a couple of things. I got rid of foot control with my TIG and use finger control and will never go back to depending on my feet 5 feet away from my hand and the weld.

Years ago a gas lens made my TIG welds look 100% better and they are all I use.

Aluminum is getting to be a toss up between the MIG with a spool gun, and TIG. It generally comes down to how much time a spend getting off the oxide and cleaning preparation. Pretty clean prepared aluminum, the spool gun gets picked most of the time. The TIG gives me cleaning and penetration knobs I don't have on my MIG.

Its puzzling but it (MIG Sgun) seems to keep the heat more consistent down the bead? That give me confidence doing fine or thin work with it. It is certainly 3X faster than TIG'ed. The spool gun "dimes" are not quite as round and there is a bit more splatter breath, but it visually passes my comparison standards.

My MIG is not pulsed, and I am looking at new machines with that that feature.

I don't agree that TIG means less warping.

This pic is typical of results I get with my MIG and spool gun on Aluminum. I use Miller.

Carl Heideman
Carl Heideman
9/18/15 12:41 p.m.

Thanks for the conversation, guys. You've added some great points and I especially like what Gasolene just said.

I want to pick up on his comment about TIG and warp--I agree completely. It a metalurgical fact that when you heat metal and it cools, it shrinks. More heat=more shrink. Apples to apples, TIG welding actually puts more heat into the base metal than MIG and therefore shrinks (more). However, it's a more malleable weld, so it's easier to get it back to its correct shape.

What happens in practice is that TIG welding tends to be more controlled in the hands of a skilled person. This person is usually better at putting the right amount of heat into the weld to make a puddle, but no more. With MIG, it's way too easy to put way too much heat in since you can't usually control the heat on the fly (except by moving the torch faster). Because of the control of the TIG, less heat=less shrink.

The easiest way to see this in action is to look at the heat-affected zone on the welds. The bigger the heat-affected zone, the more shrink (warp) you'll see, every time. Often, a good welder with TIG will have a smaller heat affected zone than an average welder with MIG. But put that same TIG person on the MIG and have it set up just right, the MIG will have a smaller heat-affected zone and less warp.

And Nohome is right, you can metal finish MIG welds. The key, just like TIG, is to have the bare minimum amount of heat to get a good weld, to try to work it as much as possible while the joint is still warm, and do what's left when it's cool. At Eclectic Motorworks, we regularly MIG dogleg and other patch panels into cars and can measure warp with a feeler gauge (.015-.020"). We could fully metal finish them if we wanted to, but at that point they can pretty much be filled with high-build primer.

It's funny, too how we've all agreed that MIG is 3X faster.

Furious_E GRM+ Memberand HalfDork
5/11/16 10:16 a.m.

In reply to rafe_999:

Do you offer any marine grade equipment? I've been looking to outfit my canoe?

paranoid_android74 SuperDork
5/11/16 11:12 a.m.

This is turning into an armada

AWSX1686 GRM+ Memberand Dork
10/26/17 9:36 a.m.

I just got started welding. First I picked up an old stick welder. Attempted to use it for a couple small things, realized it wasn't easy to use and also didn't fit my applications well. 

Now I got a Miller MIG welder, and it is so easy to use. I still have a lot of practice to do, but so far it has been incredibly easy to catch on. 

I plan to get a TIG welder sometime in the near future for aluminum, but for now the MIG does just fine. 

mikeatrpi HalfDork
10/26/17 9:58 a.m.

I know this is an older thread but I was happy to see it return to the top.  


Has anybody tried one of the new machines from Harbor Freight yet?   I have an older Lincoln SP100T MIG... but I'd love to learn to TIG for pretty stainless exhaust and aluminum bits.  

Recon1342 Reader
10/26/17 11:34 a.m.

TIG is the Zen of the welding world. It requires time and effort to get correct, but once done, is amazingly beautiful. I work in food processing, which means TIG almost exclusively for two very good reasons-

1) Cleanliness- it doesn’t throw sparks and slag everywhere, and the welds themselves are smooth and easy to keep clean on processing equipment. 

2) Stainless steel- Stainless is where TIG absolutely shines. The degree of control you get allows a strong weld while maintaining the stainless property of the base metal; incredibly important when things are cleaned daily with harsh chemicals.

NOHOME UltimaDork
10/26/17 12:18 p.m.
Recon1342 said:

TIG is the Zen of the welding world. It requires time and effort to get correct, but once done, is amazingly beautiful. I work in food processing, which means TIG almost exclusively for two very good reasons-

1) Cleanliness- it doesn’t throw sparks and slag everywhere, and the welds themselves are smooth and easy to keep clean on processing equipment. 

2) Stainless steel- Stainless is where TIG absolutely shines. The degree of control you get allows a strong weld while maintaining the stainless property of the base metal; incredibly important when things are cleaned daily with harsh chemicals.

TIG is as clean as you make it. Much of the beautiful smoke-and-spatter free process is bbecause you cleaned the weldment to surgical clean standards before you picked up the torch.

If you really want to shine with stainless, you need to learn about the joys of back-gassing the weld. This is where both the front and rear of the seam have shielding gas delivered to the puddle.


Randy_Forbes New Reader
10/26/17 12:55 p.m.

Nowadays, my recommendation to the aspiring motorsports/DIY weldor is to watch Craig's list and ebay for entry level > > NAME BRAND < < MIG machines where the seller is stepping up to a larger or one with more features.   

Please refrain from falling into the flux-core trap; even an experienced weldor can't do much better than make bird-poop looking welds.  A setup with a regulator and shielding gas is far and away better, and the when set appropriately, the gas lasts a long time (and I'm using smallish 40CF cylinders). 

Personally, all my welding machines are BLUE (including the Snap-On/Lenco Spot-II that used to be red is now also powder-coated in Miller colors).  But there are good red (Lincoln) and yellow (ESAB) units too.  I was actually impressed with a Century (Sam's Club) welder I used for a while too.

A reasonable analogy of MIG vs TIG, is much like the (getting to be...) age-old argument on the S-52 engine versus the S-54**.   Both are great I-6 engines, but to be truly happy, you need__at least__one of each!

I am happy.



**However, you'll never hear an S-54 owner belittle the S-52 by saying "it's got all its power down low..." ;)



Mark_42 New Reader
10/26/17 1:36 p.m.

I learned with Oxyacetylene, and I'm glad that it was all that I had for many years.
Brazing us under rated as well - it can be quite beautiful and strong.

Stick welding is cheap and simple. It used to be the standard go-to method.
I've done flux core wire welding, and it's like stick-lite, IMNSHO.
I setup my welder for MIG, but still haven't used it... I have a lot of flux core wire, so I keep using that.
TIG looks like fun - especially since I like Oxyacetylene welding so much. Someday I'll try it.
None of them are good or bad - each has advantages, and is usually better than nothing.

Zomby Woof
Zomby Woof PowerDork
10/26/17 1:40 p.m.
Mark_42 said:

None of them are good or bad - each has advantages, and is usually better than nothing.

Now there's advice you can take to the bank.

Welding is usually better than not welding.

Recon1342 Reader
10/26/17 2:05 p.m.

In reply to NOHOME :

I’m familiar with purge welding. We do it on sanitary piping on a regular basis. Probably one of the hardest forms of welding to learn...

Don49 HalfDork
10/26/17 2:50 p.m.

I have mig, tig, stick and gas. Different horses for different courses.

Jere Dork
10/26/17 4:32 p.m.

For those that are hobbyists and usually poor or broke I suggest gas. Everything I have was free or very cheap and has paid for itself 10x over... Maybe this varies by region but this stuff gets thrown away because no one takes it off the free Craigslist ads or yard sales asking pennies on the c note of initial costs. 

Don't believe it browse Craigslists for torches. Most people can't even identify this stuff

Coupefan Reader
10/26/17 6:38 p.m.

No angry emails.  We just like to tell you why your wrong wink.  We strictly use a TIG  here in our facility to help construct a certain precision device mentioned in a certain sci-fi empire tv show (though primitive from their perspective).  

alfadriver GRM+ Memberand MegaDork
10/26/17 7:28 p.m.
Jere said:

For those that are hobbyists and usually poor or broke I suggest gas. Everything I have was free or very cheap and has paid for itself 10x over... Maybe this varies by region but this stuff gets thrown away because no one takes it off the free Craigslist ads or yard sales asking pennies on the c note of initial costs. 

Don't believe it browse Craigslists for torches. Most people can't even identify this stuff

I was going to bring up cost of MIG v TIG, especially considering the nominal stuff we weld.

But you beat that argument.  I wish I learned how to gas weld- as it's one of the most robust things to learn.  Instead, my wife bought me a MIG, which I love to use.  For a pretty nice 110 welder- it's 1/2 the price of a TIG one, and it turns out that the odds of me actually needing TIG specific welding is still on the zero line.  I've needed brazing skills more than TIG.

No doubt in my mind the greatness of TIG welding- none at all.  I have see work of art welding on that, too.  Just that even the mild steel I do weld, it would be a pain.

Anyway, the the best answer was already posted- it depends- all have their advantages, all have thier compromises.

11/2/17 12:04 a.m.


As a metal fabricator and welder of forty years, with time as a welding instructor, I have some nits to pick with this article.

AC is used on aluminum not  for "dirty" metal, but to remove the non conductive aluminum oxide that forms on aluminum  (in minutes). You can weld TIG aluminum with DC current(reverse polarity) so long as the material is thin and you use a heavier than usual electrode.

Shield gas doesn't clean anything, it protects the molten metal of the weld from oxygen in the air, that would react with  (oxidize) the molten metal, destroying it's mechanical properties.

The fast cooling of a MIG weld is rarely an advantage. Harder, more brittle steel isn't generally a good thing in a welded assembly.

The flexibility and controllability of TIG cannot be overstated. I can weld the aluminum foil off a gum wrapper with  the same machine I can TIG braze 4130, or weld titanium, or fix a trailer hitch. Changing from one setup to another takes just minutes.

When you pull the trigger on a MIG gun, you are committed, if the machine isn't set up right for that joint, you are out of luck. If you don't have a tIG machine set up perfectly for that joint, you can  often compensate  mid weld, or stop and readjust the machine, with no problems. Screw up  the setup on MIG, and you'll be grinding away a weld. Test setups? Sure, but you don't always have that option

The flux in flux core or stick welding does have some "cleaning" affect, in that it ties up surface contamination to be chipped off as scale when cool, but it's primary function is to keep air away from the hot metal.

MIG is only faster than TIG if you don't care much about looks. Any part that will be visible or painted will require post weld finishing if MIG'd, not if TIG'd .That usually more than sucks up any time saved during the weld.

It's much harder to make a MIG joint as strong as a TIG joint, and very  much harder  than most guys realize. MIG joints can look good but penetrate very poorly (weak and prone to fail), a good looking TIG weld will rarely fail.

MIG is for when your welding is measured in feet of bead per minute. TIG is a better method for most strength critical applications, which, IMO, is anything on a car.

Including roll cages. Most of the time spent on a cage is cutting and fitting tube, not in the welding, even if you TIG.

It's not hard to learn to TIG, I've taught women who have never worked with metal at all, to TIG aluminum  in less than four hours, stainless in two. Guys generally take about twice as long, they aren't as good at listening.



BA5 GRM+ Memberand Reader
2/18/21 8:06 a.m.

I know it's fun to endlessly discuss and argue the various minutia of welding, but I'm going to suggest the following with pretty much 100% confidence:

For home welding and engineering: so long as you get the two pieces of metal melted together with roughly the right filler metal, it doesn't matter what process you use or how it looks.

There are so many other unknowns and odds are that your design is so overbuilt (or underbuilt) that it'll never matter that ER70 MIG might fail at 5x10^5 fully reversed cycles vs 2x10^6.

Flux cored MIG all the way!


They are, of course, different in terms of ease of use and aesthetics.  But in terms of "will it break if I do it one way or the other" none of that is really the critical factor in our home brew designs.

11/27/21 6:40 a.m.

MIG welding, on the other hand, involves feeding a wire to an electrode, which fuses your project together. https://protigwelders.com/tig-welder-vs-mig-welder/

CrustyRedXpress GRM+ Memberand HalfDork
11/27/21 9:43 a.m.

I've read a couple of these articles now and don't see many people talking fumes and cancer. There is enough scientific evidence that welding causes a couple of different types of cancer and the UK has mandated workplace rules around venting the fumes and wearing respiratory equipment. 


From memory, TIG welding creates less fumes but proper venting and a respirator are still necessary. Is this an over-reaction for the home hobbyist? Maybe, but lung cancer is a bad way to go and I'll be setting up a vent system and using a mask when i get around to buying a TIG.


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