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MIG vs. TIG


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#1 johnc

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Posted 12 December 2005 - 08:57 AM

From "Mr. TIG" (http://www.tigdepot.com):

So....you purchased a MIG machine. You took it home and immediately plugged it in to "test" your skills on long awaited home projects. You have fairly good results and your chest swells with pride. Your machine is typically set-up with "gasless" filler material commonly known as "Flux Core". It welds ok, but you find that if you want "clean" results you need a bottle of Argon/Co2 75/25% mix and "bare" filler wire. You then read in the instruction manual that you can weld aluminum, but you need to change the wire feed rolls and replace the Steel Gun Liner with a near frictionless "Poly" or plastic Liner........Oh, and don't forget that now you need to get a new bottle of 100% Argon for aluminum.

Now that you have made the changes in your system, purchased or leased the additional gas bottle, changed the filler to aluminum, you are ready to go. Once you pull the trigger you are quickly surprised and almost disillusioned with the results. It would be kind to say you produced a weld. In fact, the results are HORRIBLE!! Fear not! You are one of millions that believed you would get excellent results from your machine. The fact is, MIG (metallic inert gas welding) is very easy to learn when applied to Steel applications. The less expensive machines, (under $500.00) typically do not have precise controls and are difficult to "tune-in" to thin materials, (under 16 ga.). They also are not good for material in excess of 1/8", therefore, your window of opportunity is 1/8" to 1/4" steel.

Enter TIG Welding.................the TIG welding process, commonly known as "Heliarc" allows you to weld most weldable materials including 4130 Cr-Mo, Stainless, Aluminum, Titanium, Magnesium and many other materials. Not only can you weld a variety of materials, but with the variable "foot control" you can adjust amperage on the fly and weld super-thin materials, typically as thin as 24 ga. Using only Argon gas, it allows you to weld all of the materials mentioned, so what's the catch? Simply put.............TIG requires more skill. Very much like gas welding, you have to manually apply or "dab" filler material into the puddle using cut length alloys of diameters of your choice. The TIG torch provides the heat source through tungsten and you hold the tungsten directly above the area you are welding. Depress the "foot control" (very much like a car accelerator) until you see a "liquid" puddle. Dab the filler into the base of the puddle, (not the middle), and move at a slow consistent speed, dabbing the puddle as you go. This method of welding is slower than MIG, however, cold lapping is virtually non-existent with TIG, whereas it is somewhat common in MIG.

Why isn't everyone using TIG? For many years the TIG machines were extremely expensive and were focused towards industry. Now, the hobbyist, hot rodder, motorcycle builder or kit plane builder are the focus of attention. Machines are now smaller, lower cost, designed for the garage, (power requirements are 115V and 220V and typically require no more than a 50 amp circuit). So the best way to get started with TIG is to................get started!!

MIG TIG

Cost..........................................$150-600.......$550-$1800
Material thickness (steel)..............up to 1/4".......same
Productivity................................fast...............slow
Quality.......................................average.........excellent
Variety of materials.......................limited...........most
Skills Required..............................2-4 hours......20-40 hours
Thin materials (24 to 16 ga)...........difficult..........easy
Thick materials............................easy..............easy

Note: comparisons are based on the home hobbyist and machines not rated at more than 185 amps. Material thickness based on steel applications. Hours for Skill building reflect a level of "feeling comfortable" with the process.

Good luck, Mister TIG


----- John Coffey, Fabricator at Benton Performance, LLC

#2 AK-Z

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Posted 12 December 2005 - 09:38 AM

Good stuff, but all review for me.

I would like to contribute some info:

For body work, use a MIG. It causes less heat thus less metal warpage (spot welds).

For structural pieces or not finish work use TIG. It has more penetration in the base metal and welds at a higher temp thus letting the metal cool slower which makes it stronger than what you would produce with MIG.

Metal Prep is paramount and can ultimately effect how a weld will turn out.

I suggest getting a second argon tank for purging if you plan on welding tubing with TIG, so use use it to run argon through the tube and weld the outside, not an issue if you're welding chromemoly.


Oh I just noticed: MIG vs "TIC" ?
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#3 johnc

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Posted 12 December 2005 - 09:48 AM

Spelling problems... :redface:

I suggest getting a second argon tank for purging if you plan on welding tubing with TIG, so use use it to run argon through the tube and weld the outside, not an issue if you're welding chromemoly.


You can use your existing tank just add a split after the regualtor and use bronze wool to seal the tubing ends. BTW... purging behind stainless and aluminum is important and its also important for 4130. Much less important for mild steel.
----- John Coffey, Fabricator at Benton Performance, LLC

#4 AK-Z

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Posted 12 December 2005 - 09:58 AM

I guess you can do that, but its just more of a hassel another hose on when most of the work doesn't require it. Plus I like it when I forget about the second tank and find out I need to get more argon, just swap the tanks out and get the empty one refilled later.:)
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#5 Mikelly

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Posted 12 December 2005 - 11:18 AM

The advantages of MIG show through with a good, tunable machine. These "under $500" machines don't allow that tunability. Simply put, the range is so limited, I wouldn't dream of buying one.

Mike :cool:

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#6 Cruez

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Posted 12 December 2005 - 11:42 AM

I'll be in the market for one of the two in the spring.. Still haven't made up my mind on which.
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#7 vashonz

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Posted 12 December 2005 - 12:46 PM

I'm pretty sure that GTAW would probably be better for bodywork and finish welding, just because of the control you have over the heat. I know that at weld school we have to keep the NiCu under 350 degrees while welding. MIG is probably used more often because its fast and easy.

What I like about the GTAW machines we use is that you can do SMAW by just changing out the cup for a stinger and flipping a few switches. SMAW is nice because its fast, while still having control over the weld.
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#8 Pop N Wood

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Posted 12 December 2005 - 02:04 PM

IMO if you are questioning whether you need a TIG or MIG, then you aren't doing enough welding to make the TIG cost effective. The opinion does not apply if you have more money than you know what to do with.

In other words if you have to ask....

#9 Mikelly

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Posted 12 December 2005 - 03:24 PM

Bingo POP... Tig is not only expensive, but extremely hard to learn, but well worth the final product.

I'll stick with MIG for now... I weld quite a bit, but not enough to justify TIG.

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#10 Cruez

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Posted 12 December 2005 - 03:40 PM

Myself, I have ever TIG welded before..

Mig welding I do Ok, but it was with flux cored wire... so it wasn't very pretty..

Oxyacetylene welding, on the other hand I do very good at. Very clean, even welds with it...very nice beads.

Now having said that, wouldn't the TIG welding fall in between gas and mig welding... as far as the process goes.??
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#11 AdrianZ

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Posted 12 December 2005 - 04:08 PM

I can't think of the words i want to use but they will come to me later and i'll edit this

Mig high metal output (you put down a lot of wire) lower heat induced
tig less metal more eat induced more likely to warp.

I still like Tig over mig whenever i can. i like the cleaner look. but you still got to mig sometimes

#12 Pop N Wood

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Posted 12 December 2005 - 04:39 PM

Myself, I have ever TIG welded before..

Mig welding I do Ok, but it was with flux cored wire... so it wasn't very pretty..

Oxyacetylene welding, on the other hand I do very good at. Very clean, even welds with it...very nice beads.

Now having said that, wouldn't the TIG welding fall in between gas and mig welding... as far as the process goes.??


If you can gas weld, then you will probably do pretty well TIG welding. You need both hands with TIG. One to work the torch (arc) and the other to feed the filler rod into the weld pool. The TIG torch can be used to work the weld pool around. Guys who have only MIG welded have a harder time adapting to the separate heat and feed motions.

I bought a gas set up in high school because our old house couldn't support an electric machine. I got very good at gas welding. The couple of times I TIG welded it worked well also. I still suck at MIG welding, although I seem to be getting better at it. I really miss being able to pull the fill rod out and angling the torch to get the penetration I want. With a TIG/gas set up, the slower you go the more penetration you get. It took something JohnC said to make me realize that doesn't work with MIG. Go too slow and you just end up welding on top of your new bead.

#13 mom'sZ

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Posted 12 December 2005 - 04:40 PM

Thanks John for a great post. The thing I walked away with was how economical TIG machines have become. Price range is still high for a hobbist but within reason. I to will be in the market for a welder shortly. Having done collision, restoration and bodywork for twenty five years, I am no stranger to a MIG machine. I'm quite certain I could teach a smart dexterous chimpanzee how to MIG weld in less then five minutes... ANYBODY can do it. point, push button, weld. TIG on the other hand, is more difficult to master. Cruez, you say you can oxy acetylene weld? Well you would be a good candidate for someone who could pick up TIG welding pretty well. It is similiar in that as the article states, you feed in filler rod with one hand while positioning the heat source (the electrode) with the other. When you gas weld you hold the rod in one hand and the torch in the other. Unlike a mig, you control how much filler is added using judgement learned through practice. You learn to hold the tip of the torch just so to heat the area you need to weld.
When I did a lot of panel replacement, a MIG was the tool of choice for bodywork. Doing factory recommended unibody repair meant doing spot welds, lot of them. Usually quarter inch holes are punched or drill in one panel and the hole then filled to join the two panels. A MIG was fast, reducing warpage. You dial in the heat and wire speed on the first few welds, then go to town. Like Mike said the lower end stuff is not very adjustable so you are limited. For years at work we used a Millermatic. It was a great machine. I did a couple year stint in a machine shop that did mostly racing stuff. The owner had a nice TIG and what he could weld with it was amazing, all the way from paper thin steel all the way up to cast magnesium casings.

#14 SHO-Z

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Posted 12 December 2005 - 04:44 PM

You can TIG weld stainless and carbon steel with any DC welding machine using straight polarity. Carbon does not need to be purged on the back side. I have seen a TIG pulse arc machine weld an aluminum Budweiser beer can back together, talk about low heat input.
Aluminum is where you need the square wave Tig machine.
I worked as a certified pipe welder for years, never used a MIG welder in the field. I have a MIG welder with gas shield in my garage now and it will work on most any project that I have. I would like to have a DC machine for Stick and Tig welding, but really do not have any project coming up that it is needed.

#15 clarkspeed

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Posted 12 December 2005 - 04:51 PM

Who makes a $550 TIG machine? As an engineer I spent some time in the heavy manufacturing industry and was actually a part time (pretend) weld engineer. I've sourced many units and have always wanted to get one for myself but couldn't afford it. Most of the used units I delt with were over $1000. I've been away from the industry for awhile but I've never seen an entry level TIG for less than $1000.
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#16 Cruez

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Posted 12 December 2005 - 05:05 PM

If you can gas weld, then you will probably do pretty well TIG welding. You need both hands with TIG. One to work the torch (arc) and the other to feed the filler rod into the weld pool. The TIG torch can be used to work the weld pool around. Guys who have only MIG welded have a harder time adapting to the separate heat and feed motions.


Thats what I was thinking about the TIG welding.. I think I would pick it up pretty easily.

Come spring, (when my bonus arrives :) ) I think I am seriously going to look at a TIG unit.. personally, I think it would suit me better than a MIG unit would.
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#17 OlderThanMe

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Posted 12 December 2005 - 05:06 PM

harbor freight has a DC GTAW welder for $350 before tank and regulator... I am saving for a Miller Dynasty 200DX. I am in welding school and have been GTAW welding for about a year and have been able to make some beautiful welds on mild steel, stainless, and aluminium...GTAW is definitely my favorite process of them all. And if you can weld with oxyfuel then GTAW will be easy. I have also welded Mig and am takeing my last course in overhead SMAW welding and Prep for Industrial Qualification starting in January.

#18 260DET

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Posted 12 December 2005 - 06:47 PM

Is 25amps low enough for a MIG to do bodywork? Is'nt there some sort of spray on stuff you can use to improve the finish of non-gas MIG welds?

#19 AK-Z

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Posted 12 December 2005 - 07:37 PM

I have seen a TIG pulse arc machine weld an aluminum Budweiser beer can back together, talk about low heat input.
Aluminum is where you need the square wave Tig machine.


For body work, its also about application of heat also. The area of the base metal that the heat/arc is applied is much greater with TIG than with MIG spot welding. You can do Body work with TIG but MIG does a much cleaner job (after dressiing the welds) and is more cost effective.
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#20 CruxGNZ

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Posted 12 December 2005 - 07:53 PM

GTAW = Gas tungsten arc welding (TIG)
SMAW = ?
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