Welding 101

Simply stated, welding is the joining of two metals with intense heat.  As someone who has never really welded before, I've always been fascinated by this trade.  There is just something studly about working with metal.

Real men work with steel

My first introduction to welding came after I graduated from medical school.  With a month off before I was to start my internship, I decided to sign up for a welding class at the local community college.  I figured this would add an excellent skill to my DIY arsenal as well as offer a much needed distraction while I awaited the impending sleep deprivation and ego-pummeling that would invariably define my life as an intern.  I bought a welder's helmet, apron, gloves and a few other basics that were required for the class.

This is how cheesy I must have looked on my first day of class

On the first day of class, we got to run some beads with a standard MIG welder and also got to try the plasma cutter.  I was pretty excited about how hands-on the course seemed and was confident that by the end I would be semi-proficient with basic welding techniques.  Unfortunately, the following week I had to have surgery on my foot and was made non-weight bearing for a month...so that first class was the extent of my formal welding education.

This was me after I "dropped out" of my welding class...just look how young I looked!  Man, internship and residency really ages you!

Fast forward 8 years...I haven't touched a welder since that first class and now find myself confronted with a giant welding project.  Fortunately, my awesome wife was serendipitously one step ahead of me--she bought me a MIG welder for my birthday earlier this year!

World's coolest birthday gift...thanks, honey!  You rock!

So let's see....I have the steel, a welder, the safety gear, and an abundance of naivete.  Never one to shy away from a challenge, I did what I always do when I have no clue about the next step...I read some books.

 

 

After a healthy dose of self-directed learning, the once mysterious world of welding started making quite a bit of sense.  As most people know, there are several different types of welding--shielded metal arc welding, flux-cored arc metal welding, tungsten inert gas welding (aka "TIG welding), metal inert gas welding (aka MIG welding), and several other less common types typically used in specialized industrial applications.  Most hobbyists like myself gravitate to MIG welding due to its relatively short learning curve and broad range of applications.

In a nutshell, MIG welding is quite simple.  The goal is to join two pieces of metal by melting them together.  In the case of my stair project, I am using mild steel which melts around 2,500 degrees Fahrenheit--that's pretty hot.

To achieve such a high temperature in a small, controlled area, the welder uses electricity.  Current enters the welder and is sent through the conductive metal wire which is wrapped around a spool.
 

Inside a MIG welder

The wire is actually stranded mild steel coated in copper...the copper coating increases the wire's conductivity and allows the electricity to flow efficiently to the area being welded.  There is also a ground clamp connected to the welder...this gets clamped to the work piece and allows for completion of the electrical circuit.  The stranded wire is fed from the spool through the long hose connected to the welding gun where the wire exits near the weld site.  The electrical current arcs to the work surface and generates intense heat. At the same time, inert gas is expelled from the gun nozzle  to create a contaminant-free micro-environment around the weld.  Here's a crude, but easy to understand schematic:

Here is a close up of what happens at the tip of the welding gun:
 

Within this shielded "micro-environment," the arcing electricity generates enough heat to melt the work surface and the extruded wire...a molten state occurs and the metals fuse.  Air then cools the metal and viola...you have your weld!

Unfortunately, the concepts behind MIG welding are much easier to grasp than the actual techniques required to execute a good weld.  Like most trades, welding takes practice....lots of practice.

Practice & Repetition...there are no shortcuts

Before one can produce structurally sound and aesthetically acceptable welds, he/she must learn to manage all the variables that can effect the MIG process.  Things like wire feed rate, voltage, and gun travel speed all require adjustments depending upon the thickness of one's work surface, the type of joint being welded, and the gauge of wire being used.  Needless to say, I had some work ahead of me...oh well, I guess there's nothing to do but to get busy practicing.

Yes, this really is me...I do all my own stunts