I got something fancy for Christmas this year.
This is my new TIG welding machine, which I’ve already christened in the typical Practical
Engineering fashion.
I’m a welding newbie and currently absorbing anything I can on the subject, so while I
learn, I thought I would take the time to boil down some of that new knowledge and share
it with you.
Now, this is welding for the guys and girls at the front of the class who never set foot
in the machine shop You know who I’m talking about: the marching band members, the geeks,
the nerds.
We’re not going to obfuscate things with bumblefudgery and Canadian syllogisms.
In other words, if you already nail the keyhole on your root pass, this video might just be
a bit elementary.
I’m Grady and this is Practical Engineering.
On this episode we’re talking Welding 101 for hobbyists.
For our purposes, we’ll define welding as a way to join metals using fusion.
That fusion is what makes welding different than brazing or soldering.
When you’re joining metals, you have two parts, the base metal, and the sometimes optional
filler metal you use to reinforce the joint.
With brazing and soldering, the heat is only enough to melt the filler metal and not the
base metal.
This is the metal equivalent to how most glues work.
With welding, on the other hand, the base metals are melted so that fusion can occur.
The two metals actually become one.
"Set your spirit free, it’s the only way to be…"
Little spice girls reference for you.
In general, and compared to other common building materials, metals have excellent mechanical
properties.
They are hard, tough, strong, and durable.
As someone who, and I hesitate to say it on a welding video, occasionally works the wood,
even I can admit that metals are a superior material in many regards.
So you can see why it would be advantageous to have a way to connect them together, especially
if you can do it in such a way that joint isn’t the weakest part of your assembly.
That’s the goal of welding, and luckily, this is not something reserved for industrial
factories and machine shops.
From my own experiences so far, welding is something you might be able to do yourself
as a hobby.
And stay tuned till the end for some tips for getting started.
Welding requires two essential ingredients: heat and protection from the atmosphere.
The heat, of course, is necessary to melt the pieces of metal being welded so that can
fuse together.
The shielding is necessary because molten metals easily oxidize and absorb atmospheric
contaminants.
These impurities will weaken a weld or prevent good fusion all together, so some kind of
shielding is usually required.
Now, there are a lot of ways to make heat.
That’s actually a fundamental law of the universe, but it’s also true in the more
specific sense here.
So, as you can imagine, with only those two basic requirements, a litany of welding methods
have been developed using different permutations of heat and shielding.
Luckily for me as the writer of this video, only a few of those methods are widely accessible
to hobbyists.
Today we’ll talk briefly about five.
The first is oxy-fuel welding, also known as gas or torch welding.
In this method, the heat comes from the combustion of a mixture of pure oxygen and some other
gas, usually acetylene.
This combination creates an extremely hot flame which can exceed the melting point of
most metals.
The shielding comes from the flame envelope and gases generated by the combustion (mainly
carbon dioxide).
With oxy-fuel welding, you use the torch to generate a puddle of molten metal.
With your other hand you add filler metal to the weld.
It’s a very simple process and one of the oldest methods of welding.
Advantages are that it feels really awesome to hold an oxy-acetylene torch, it doesn’t
require any electricity, and the torch can also be used for other purposes like cutting,
so you can get a lot of uses out of a single tool.
Disadvantages are that you have to have two high pressure tanks of flammable gases nearby,
and the torch is kind of unwieldy which leads to slower and less-consistent welding.
For the next four types of welding, the heat comes from generating an electrical arc between
an electrode and the metal.
You’ve got the short I-sound nicknames: Stick, MIG, and TIG, and I’ll sneak flux-core
in next to MIG, since you can usually use the same machine for both processes.
Probably the most common type of welding is shielded metal arc welding, also known as
stick welding.
This process uses a power supply to maintain an arc between the electrode and base metal.
In stick welding, the electrode is also the filler metal, and it’s surrounded by flux
which melts during the welding process.
When an arc is struck, the heat generated melts both the base metal and the electrode,
causing them to fuse together.
The flux coating also disintegrates, generating both a shielding gas and slag which absorbs
impurities and creates a protective covering over the weld as it cools.
Stick welding is so popular because of its simplicity and versatility.
Constant current power supplies are fairly inexpensive compared to other welding machines,
and stick welding can be performed in almost any environment, including underwater.
Disadvantages are that it only works for certain metals (mostly iron and steel) and that it
can be a fairly messy process with lots of molten spatter and fumes.
Next up are the two wire-feed welding methods.
Gas Metal Arc Welding, also known as MIG, and flux core arc welding.
Both MIG and flux core welding use a constant voltage power supply to generate the arc,
and a wire feed mechanism for the electrode which is also filler metal.
Just like in stick welding, the arc melts both the electrode and the base metal, allowing
them to fuse together into a weld.
For MIG, the shielding comes from an inert gas (that’s the IG in MIG) that surrounds
the arc during the weld.
Usually the gas shield is a mixture of argon and carbon dioxide.
As its name implies, flux-core welding uses a tubular electrode with flux in the center.
The flux shields the weld by generating gas and slag just like with stick welding.
You can use both an inert gas and flux-cored wire, a process known as dual shield welding.
Gas Metal Arc and Flux-core arc are two of the fastest welding methods in terms of deposition
rate, since you don’t have to stop to get a new rod.
MIG and flux core welding are also considered the easiest methods to learn because there
are fewer variables to control during the process.
MIG is generally an inside process, since wind can blow away the shielding gas, but
flux-core can be used in most environments just like stick welding.
Finally, we have gas tungsten arc welding or TIG welding.
This process is much like torch welding.
In fact the business end of a TIG welder is also called a torch.
When TIG welding, the arc passes between the electrode and the metal, but unlike in the
other processes we’ve discussed, the electrode doesn’t melt since it’s made of a tungsten
alloy.
Instead, filler metal is added to the weld puddle with your other hand.
The puddle and arc are shielded from the atmosphere by the IG in TIG, usually pure argon gas,
which is focused around the weld by a ceramic cup.
TIG is the most precise of the techniques we’ve discussed, because you have much greater
control over the length and current of the arc, the rate at which filler metal is added,
and other important variables which can affect weld quality.
That control also makes TIG the most appropriate method for welding thin materials and non-ferrous
metals like aluminum, magnesium, and even titanium.
For the same reason though, it’s probably the most challenging process to master, and
usually the slowest.
To get started welding requires some equipment, most importantly a welding machine or oxy-fuel
setup.
Many machines on the market today can perform more than one welding process, so you don’t
always have to choose a single one.
However, like many hobbies, there is some rabid brand loyalty when it comes to arc welders,
so make sure you choose the right color.
You don’t want to come home with a Lincoln only to find out that your wife only goes
for Miller guys.
And don’t forget safety.
Like any hobby that involves searingly bright lights, molten metals, and high voltages,
welding can be hazardous.
Consider the dangers before welcoming one of these machines into your home, and if you’re
budgeting to get started in the hobby, don’t forget all of the safety gear you’ll need
as well.
Like I mentioned at the start, I’m new to welding as well, so I’m far from your best
resource on the subject.
Luckily for all of us, there are a few people on YouTube putting out incredible educational
content for free, two of whom were kind enough to share footage with me for use in this video.
Jody from Welding Tips and Tricks makes awesome videos about welding including beautiful arc
shots so you can see exactly what’s happening when he welds.
This Old Tony makes extremely well-produced machine shop videos that are big on fundamentals.
Do yourself a favor and go subscribe to both of these channels.
I promise you will not regret it.
Huge thanks to both of these guys for letting me use some of their footage.
Finally thanks to the sponsor of this video: Great Courses Plus.
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Thank you for watching and let me know what you think.