TIG Weld Like A Pro
Welding tips to take you from zero to hero!
From the December, 2011 issue of Popular Hot Rodding
By Christopher Campbell
Photography by The Author
TIG welding—also known as gas-tungsten-arc welding (GTAW)—is the craftsman welding method of choice, and elevates simple fusion of metals to an art. Mastery earns a certain level of respect in the fabrication world. To some it’s akin to a black art, others think you have to have the rhythm and precision of John Bonham on the drums to choreograph all the movements. That’s all a little bit true. It’s also true that with enough practice and some basic knowledge, you can learn to TIG like a pro.
To begin, there’s no such...
To begin, there’s no such thing as too nice of a machine; the more advanced the equipment, the easier it is to create nice welds. Also, they leave room to grow once you’ve moved past the beginner stage. The water-cooled Lincoln Electric Precision TIG 275 and the Ready-Pak we’ve been using for fabrication on Max Effort is a great package for home and shop.
So what’s so cool about TIG? Firstly, it’s the most versatile method of welding and can be used to weld just about any metal: steel, stainless steel, chromoly, aluminum, nickel alloys, magnesium, titanium, copper, brass, bronze, and even gold. It’s also the cleanest form of welding with no sparks, spatter, flux, or slag produced. And assuming you properly cleaned the metals, you won’t have any real smoke or fumes to speak of.
But we know why most people are interested: It’s the look. You just can’t beat the beauty of a well-laid TIG weld. That beauty happens because TIG welding offers the highest level of arc and weld puddle control since the heat input is controlled by the human welder, allowing the puddle to be heated up or cooled down as necessary. That’s how that beautiful bead comes to be.
While working through our fabrication adventure, otherwise known as project Max Effort, we were always impressed with Ryan Kertz of Kertz Fabrication, and his ability to lay down perfect TIG beads every time, while ours are usually ... well, less perfect.
The biggest problem, Kertz explained, is that while it’s true that the only way to learn is to just pick up a torch and do it, there are a handful of very basic tips and techniques he has observed often that keep the uninitiated from advancing quicker. If you’ve not had the benefit of a welding class, instruction from an experienced welder, or at least a good instruction book, these tips here may be some of the reasons you’ve been fighting to improve.
|Lincoln Electric Ready-Pak
|Precision TIG 275 welder
|Under-Cooler cart water cooler
|Gas regulator/flowmeter and 10-foot hose kit
|PTW-20 Pro-Torch TIG torch (250 amp, 25 feet)
|Zippered torch cover
|Water hose (two included)
|15-foot work cable and clamp
|Adapter for optional PTA-9 or 17 Torch (3/8 inch)
||Minimum output preset control and display switch (also displays output voltage)
||Setup menu for D/C TIG start modes, pre-flow time, and start pulse for soft or forceful starts
||Digital amperage meter
||Local/remote current control switch
||Maximum output preset control
||Thermal shutdown light
||A/C balance control
At the bottom of the unit...
At the bottom of the unit we have the power switch and polarity switch. For steel we’ll be welding DC negative; AC TIG is for aluminum and magnesium, for example. We’ll be addressing mild steel here since it’s the simplest and most common material to TIG weld.
Welds like to happen in an...
Welds like to happen in an inert environment, but we live in one full of reactive gases, so a shielding gas is employed to keep impurities out of the weld. Whereas MIG likes a compressed mixture of 75 percent argon and 25 percent carbon dioxide, TIG prefers 100 percent argon gas.
Even without the advanced...
Even without the advanced panel, high-end TIG machines have a lot of options that can intimidate beginners. Definitely review the operator’s manual to familiarize yourself and discover baseline settings for your metal, but don’t overthink it too much when you’re learning, since many of these controls are designed for pros. It’s much more than we can get into here, but clockwise around the panel we have:
The rule of thumb with gas...
The rule of thumb with gas flow is to use as little as necessary. You don’t want to waste expensive gas, and excessive gas can actually work against the weld. You do need decent ventilation, but try to avoid windy conditions and drafts since they’ll just blow away your shielding gas and increase the odds of contamination and porosity.
This is what a TIG weld attempted...
This is what a TIG weld attempted without shielding gas looks like; note the heavy pitting and porosity. Welding with too little shielding gas present will produce a less drastic version of this.
It’s a common misconception...
It’s a common misconception that the lens shade number corresponds to the amount of protection that is provided to the eyes, and hence the higher the number, the better the protection. In reality all quality welding lenses filter out 100 percent of the harmful ultraviolet (UV) and infrared (IR) wavelengths to protect eyes. The number just denotes the level of shade of the lens.
The tungsten rod is the electrode...
The tungsten rod is the electrode that transfers all of the current to create the weld since its melting point (6,192 degrees) is far above anything else you’ll be welding. There are several types available, but to keep things simple you can start with lanthanated. Consider it an all-purpose tungsten that will work on carbon steels, stainless steel, nickel alloys, aluminum, magnesium, titanium, cobalt, copper alloys, pot metal, and just about everything else. Size should be proportionate to the amount of current you need to use. Common 1/16, 3/32, and 1/8 sizes are good for 70-140A, 70-140A, 200- 310A, respectively.
Here’s another area where...
Here’s another area where a gas lens helps dramatically: tight corners. To get this weld, Ryan Kertz extended the tungsten out a bit further than the standard 1⁄8 to � inch and turned up the gas flow a small amount. The lens will keep the column of argon directed where he needs it. Kertz used this method extensively during Max Effort’s rollcage construction.
There are two schools of thought...
There are two schools of thought on how to bench weld. One essentially says take a seat and make yourself as comfortable as possible. Kertz spends most of his time welding in cramped conditions on cars, so he prefers to not develop crutches. You’ll typically find him standing at his welding table. That’s not to say that you should use your surroundings to your advantage. For example, in any situation look for ways to stabilize your torch hand if possible. In a simple example, here Kertz used a piece of angle iron to rest his wrist on as he slides it across the table.
Tungsten doesn’t come pre-ground,...
Tungsten doesn’t come pre-ground, so you’ll need to create your tip. The general rule of thumb is to make the point roughly two and a half times the diameter and always grind with the grain using a clean abrasive. If you want to get technical, for currents under 20 amps grind the tip to about 20 degrees. For over 20 amps, grind tips to about 20 degrees and add a small flat spot to the tip.
Here’s probably one of the...
Here’s probably one of the most common mistakes for newbies: getting the working angles wrong. Ideally, you want the torch about 10 degrees from vertical away from the direction of travel The filler rod should be around 15-20 degrees from the surface. Of course tight real-life situations will create fudge factors, but for learning try to stick close to the optimum angles.
So how close does the tungsten...
So how close does the tungsten need to be to the surface? Tight. Ideally, the arc length should be roughly equivalent to the diameter of your tungsten and should stay fairly consistent without touching the tungsten to the molten metal. Definitely no more than 1⁄8 to 1⁄4 inch away from the weld puddle. Also, use the push technique since that ensures good shielding gas coverage and better visibility of the weld puddle.
Get yourself a gas lens. Our...
Get yourself a gas lens. Our Lincoln Precision TIG 275 came equipped with one, but most TIG machines will not. The one on the right is a traditional collet body; on the left is a gas lens. The gas lens uses a tiny screen to create a more laminar flow of shielding to the working area to create a cleaner (and stronger) weld. The main benefit for the newbie is that they help keep the welding surface more flushed clean and inert, letting you focusing on your technique.
The second most common error...
The second most common error is holding the filler rod improperly. Remember, the rod is consumable, so don’t hold it like a pencil. There are a few variations on this, but Kertz recommends threading it between the pointer and middle finger with the thumb used to steady. This way the rod can easily be fed by extending your fingers and pulling it forward.
With everything working in...
With everything working in concert, this is how it should look. Note that the torch is controlling the puddle, and the filler rod is just being dabbed in a dime at a time. To keep the heat consistent, you’ll actually be backing off the foot pedal that controls the amperage the tungsten delivers. Keep the speed consistent to maintain size and shape of the dimes.
One newbie mistake here is...
One newbie mistake here is not backing off on the amperage as you end to prevent cratering, and not allowing the proper amount of post flow. Post flow is the amount of shielding gas that continues to flow after you’ve finished welding. This flow prevents contamination and oxidation of the weld puddle as it solidifies. The amount of time depends upon the thickness of the metal as well as type, but around 5-7 seconds is a good starting point. This results in a structurally stronger weld that doesn’t have a potential weak spot between two weld beads. For a corner joint like this, both edges of the adjoining pieces should be melted and the weld pool should be kept on the joint centerline. You’ll also need a bit more filler rod to create a nice convex bead to suitably join the two.
This results in a structurally...
This results in a structurally stronger weld that doesn’t have a potential weak spot between two weld beads. For a corner joint like this, both edges of the adjoining pieces should be melted and the weld pool should be kept on the joint centerline. You’ll also need a bit more filler rod to create a nice convex bead to suitably join the two.
A typical angle grinder will...
A typical angle grinder will probably work for plate and sheet, but for tubing get a barrel grinder like this. Tubing cuts are rarely perfect on the first try and one of these will let you sneak up on the fitment and create much tighter and more professional joints with minimal effort.
So what happens when you accidentally...
So what happens when you accidentally touch the tungsten to the metal? You get a nice glob of metal on the end of your tungsten that needs to be ground away. Note the blackish/ brown cloud around the weld and porosity; that’s what it looks like if you try to weld with tainted tungsten. Also, though most welders skip it, it’s good practice to clip off the end of a used filler rod (ours is 1/16-inch ER70S-2 for mild steel) to prevent contamination—just like in MIG welding.
When a weld comes to an edge...
When a weld comes to an edge like shown, don’t stop the bead there as it leaves a potential place for cracks to form.
Remember what we said about...
Remember what we said about controlling the amperage with the foot pedal? When working on a joint like this, start with the area that will require the least amps, i.e. the open side, and work your way around to the tight closed side.
Here are three TIG welds to...
Here are three TIG welds to compare. The first is properly laid with the right amount of shielding gas and amperage. The second illustrates too much amperage (note the flat, molten look). The last shows too much amperage and too little shielding gas. Only the first weld would be considered strong. Also, when welding a T-joint like this the edge will melt faster, so angle the torch slightly away to direct more heat to the flat surface and dab the filler rod where the edge is melting.
Instead, always try to wrap...
Instead, always try to wrap the weld around to the back of the material to create a stronger edge. This is an especially important practice on suspension and chassis components and something we employed throughout Max Effort.
If you modulate the amperage...
If you modulate the amperage correctly, the heat signature of the weld should have a nice consistent look all the way around. Again, don’t stop where you started, lap over the beginning of the weld about � inch. One last tip: When welding a vertical piece, it is opposite of MIG welding where you weld going down. With TIG welding you start from the bottom and go up (when possible).
Cleanliness is next to godliness...
Cleanliness is next to godliness when it comes to TIG quality, since TIG is particularly sensitive to contaminants like scale, rust, paint, grease, even fingerprints, all of which can severely compromise the weld’s integrity. Right after that is tight fitment. While MIG can easily cheat and bridge large gaps with extra material, with TIG it pays to take time to make tight joints. This will not only make the weld easier and better looking, but also stronger.
Ideally you want to completely...
Ideally you want to completely weld a joint in a single pass, but in instances where you need to stop and restart, don’t pick up where you left off. Instead, step back a � inch or so (three to four dimes) and start there.