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TIG vs. MIG Welding in “Jay Leno’s Garage” [VIDEO]

The man has over 100 cars, about 90 motorcycles and enough “Benjamins” in his pockets to continue buying more. Treasures aside, what Jay Leno doesn’t have is extensive welding knowledge.

In a bid to learn more about MIG and TIG welding, Jay hooked up with Airgas engineer Ken Kosiorek on Under the Hood, an online video series with Bernard Juchli, Leno’s top guy.

This video is one of many on Jay Leno’s Garage, a website featuring articles, blogs, photos, videos and more on Leno’s extensive auto collection.

*Transcript follows



Jay: Hi. Today’s Under the Hood segment is going to be about welding. This is Ken Kosiorek from Airgas. There’s probably more misconceptions about welding than almost anything else, and I start a lot of them ‘cause I know nothing about welding; Bernard is our expert welder.

Why don’t we explain the difference between TIG welding and other types of welding.


Ken: TIG welding is called tungsten inert gas. This is an electric current going through a torch supplied by a welding machine like the Lincoln Precision TIG 275, which is a really good unit. It uses the tungsten to carry the current.

  • So that screws down to there.
  • Argon gas passes through it.
  • It creates an arc, and then you use a filler metal to fill your joint up, so you’re actually doing this.

With MIG, it’s a handheld gun. It’s like a hot caulking gun where you pull a trigger and out comes wire and electrical current and gas, and that forms your weld bead.

Jay: Ok. And which is stronger?

Ken: Well they’re both about the same strength, 70,000 tensile PSI.

Jay: And what’s the advantages of one over the other?

Ken: TIG gives you very beautiful cosmetic welds, which a lot of, especially “hot rodders” want. They want the beautiful weld; whereas MIG, it still looks good but it’s a lot faster. But TIG overall is the most beautiful weld you can get.

Jay: Ok.

Bernard: Well with TIG you usually use it on thinner materials. . .

Ken: Correct.

Bernard: . . . where the MIG, it’s fast welding speed will do like a quarter-inch, half-an-inch plate you can do real easy, which would be tough to do with this.

Ken: It’d be real slow with TIG, so there is a thickness requirement for one or the other. There’s a thickness variation.

Jay: What we gonna start with today?

Ken: I have this tack-welded together already. This is cold-rolled mild steel. There is also hot-rolled mild steel with a scale on it, and you need to differentiate the two when you’re doing welding.

Bernard: Use a little grinder like that to grind the metal down to where it’s bare and shiny like this instead of the black coating it has from hot-rolling. And then after that you can weld it.

Ken: So, I’m going to put on my safety equipment – which is my patriotic hat; I’ve got my leather jacket because with welding you can get burned, so we want to be a safe as possible. You notice there is no gasoline cans around or anything that could possibly catch on fire: rags, towels. . . Arc light can bounce off the welds though and come in here and actually burn my chin. It’s like a sunburn machine.

Jay: So it’s important to dress like Captain Acid when you’re going to be welding.

You should probably step out and not be too close to this.

Ken: The machine’s on already; it’s setup for the DC current for the steel.

Now the TIG system – it has a torch, it has a foot pedal like a car. So when I hit the foot pedal it turns the arc on, initiates it, gas flows out of it and then I strike my arc and I melt my medal and I weld.

Bernard: You can also use the foot pedal like a throttle and you can control the amount of heat.

Ken: So just image you’re in your car pushing the gas pedal, and you’ve got power.

Now we’re gonna run a small bead and show how it melts it. Again, watch your eyes.

I’m going to hold my torch here to cover the weld zone with the argon gas that protects it so the nitrogen and oxygen in the air won’t contaminate it.

In car restoration, you may have to do a plug weld like this.

We’ve lapped the metals over and we fill in a hole and it gives you a very strong joint.

Tungsten should always stay gray. If it turns black, you could probably be pulling and air from an air leak or it could be an old hose that’s cracked. So, you always want to make sure your tungsten’s gray-looking.

Thanks a lot for letting us show you the TIG process.

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