I spent the weekend at the EAA's Sportair Advanced TIG Welding class, held in Griffin, Georgia. The class encompassed two hours on Friday, eight on Saturday, and another 6 on Sunday. It's designed for homebuilders who want to hone their TIG welding skills, but even somebody who's never picked up a TIG torch could have come away welding. I was expecting to be at the bottom of the class, but it turns out I had more experience than some, and didn't do too bad.

The emphasis was on welding 4130 steel tubing, such as engine mounts and fuselage frames, but we also welded thin aluminum and stainless steel as well.

While I was hoping that we'd have somebody that knew his stuff, the "instructor" couldn't possibly have been better. Metalurgist Wyatt Swaim is an internationally known expert on the subject of welding 4130 steel and titanium. His company (Hi-Tech Welding) does a lot work for the "Skunkworks", and has extensive experience welding anything that CAN be welded, specializing in titanium. Wyatt is also the guy you'll find at the welding shop in Gasoline Alley during the month of the Indy 500 repairing the exhausts, frames, and whatever else breaks on the Indy cars.

Wyatt has embarked on a personal mission to spread the gospel of TIG welding titanium and 4130 steel. He has been instrumental in creating a soon-to-be-released AWS (American Welding Society) specification regarding the TIG welding of 4130 thin-wall tubing of the sort used for sport aircraft, racing cars, and other serious home projects. This spec will be released soon, and will debunk many of the wives-tales that have been hatched and perpetuated over the years. The spec is the result of hundreds of controlled test welds that were tested to destruction at a test lab.

I'll try to hit the highlights here. When TIG welding thin-wall 4130 tubing, no preheating is required, other than bringing it up to room temperature and ensuring that no obvious moisture is present on the tubing. Likewise, no "post heating" or normalization is required either, but a draft-free work area is important. Keeping the weld bead as small as possible is best, in order to minimize the heat-affected zone. The best welding rod to use is ER80S-D2, ER70S-2, -3, or -6, in that order. There's nothing wrong with copper coated rod, which prevents the rod from rusting. Make sure you wipe the oils (used in manufacturing) off of the rods first. .045" diameter rod is best for thin-wall, but it's not commonly available. If you can't find it, visit Wyatt's web page at www.TIGdepot.net and he'll sell you small or large quantities. (Mention you're with the EAA and you'll get a 25% discount.) Tight fit-ups are of paramount importance when TIG welding OR gas welding. The tighter the joint, the less distortion you'll encounter as the structure is welded together.

There is an age-old debate regarding which is better for welding 4130, gas or TIG. I'm here to tell you that I'll never be able to gas weld 4130 with anything near the confidence level that I can TIG it. I have no doubt that someone with years of experience can gas weld 4130 just fine, but if you want joints with the same high quality (and a smaller heat affected zone) with minimal practice, TIG is the way to go! It costs more to "get in", but it sure is easy to pick up TIG welding. There are no real variables. Just step on the pedal until it melts into a puddle, and feed it the rod. With gas welding there are so many variables. Tip sizes, oxy-acetylene ratio, etc. I never could figure it out. I proudly took an early gas attempt to the local guy that does all the certified aircraft welding for the FBOs. He just sighed and said "I'm sorry, I thought you were further along than this. You've just cooked the hell out out of it".

Much of the argument against TIG welding steel have come from the gas welding camp, who are fond of breaking TIG joints welded with "official" 4130 rod. This high carbon rod is very brittle and prone to cracking when allowed to cool quickly, as most homebuilders would tend to do when welding thin-wall tubing. 4130 steel is normalized by a carefully controlled slow-cooling process during manufacture. So when you heat it up and let it cool at room temperature, it's very strong, but far more brittle. That's why milder steel rod is best for our thin-wall application. It's far better to have a slightly weaker joint than to have a brittle one with cracks in it!

Weld up a joint using milder steel rod and you won't break it. That's exactly what Wyatt's done for the new AWS spec, and the results will be published soon.

While we practiced in the "lab" what we'd learned in the classroom...

...Wyatt welded tubing for anybody that wanted to watch...

...and even showed how to repair errors in our "abortions".

As part of his personal "mission", Wyatt is trying to make it easy for people to get into the TIG business. This includes adapting modern torches to old TIG machines, which he'll be happy to help you with if you give him a call. He is even developing new products to make TIG welding easier (by working with the manufacturers to bring to market a 110V version), more accurate (higher frequencies), and less tiresome (very flexible torch hoses). You can also call Karen at 1-800-456-9172 for answers to your TIG questions.

Wyatt has created a website named www.TIGdepot.net , which will soon become THE clearinghouse for TIG welding knowledge, including the aforementioned AWS welding spec, recommendations regarding rod and electrodes diameter and material properties, and as many TIG welding FAQs as he can find or generate. It's his personal crusade.

Wyatt never travels without his aluminum foil, which he uses to enclose the backside of stainless steel that he intends to weld.

Argon is flowed into the resulting volume, eliminating the "brown sugar" chromium oxide that normally results on the unprotected backside. The other side of the weld was actually more beautiful than the front side.

All the sudden, back-purging doesn't look so painful anymore! Just fill your exhaust system with argon and rest assured that it will last for hundreds of hours rather than just hours. It's like night and day. Another myth that got debunked (from personal experience) is that stainless is hard to weld. It's actually EASIER than plain steel, because it's so much cleaner.

There were only six of us in this particular class, and the participants were from as far away as Maine. We had two engineers, two airline A&Ps, a professional welder, and a homebuilder in attendance. These classes are normally for twelve, but since 9-11 they have been a little shy of that number. Let's make sure that doesn't happen again!

This guy really knows his business. I learned more during this weekend than the last 6 months of playing around with my Square Wave 175. I left here knowing that the sorriest looking weld that I did while I was here was "good enough to fly behind"! That basically says that I'm good to go! There is no substitute for watching somebody that knows what they're doing weld, nor having them watch you weld! This class was worth every penny and more.

The next Sportair Advanced TIG Welding class will be May 1st. The next class that Wyatt teaches will be June 8-10, also in Griffin. See http://www.eaa.org/communications/eaanews/010216_tig.html for exact details of that class. Be there! Here are some comments by an EAA member who attended the May class last year, at http://w3.one.net/~fhoward/eaa/newsletters/newsletter_may_2000.htm . Many thanks to Lincoln Electric for supplying all of the welders and material for this class, and to Wyatt for making the trip from California to help us out.

If anybody needs a high resolution image of one of these pictures (these are reduced to 25% of original resolution, and then compressed by another 90% to get the size down) let me know and I'll email them to you.

Please report corrections to Mark at langford@hiwaay.net.

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