Obviously it’s safety first when you’re learning to weld. That is common
sense, but I say that so you’re sure to remember: welding is dangerous. Welders
throw sparks; they set things on fire. Make sure anything in the area around you
that could possibly ignite is removed. If you are outside, near grass or bushes,
wet them with a hose.
Your skin—and your hair—can burn. Wear a long sleeve shirt, long,
non-flammable pants without cuffs and leather welding gloves. - A good eye
shield or welding hood must be used.
Keep a fire extinguisher near you when you are welding.
Don’t Mig or arc weld where water is in contact with you or your
welding surface. You risk electrocution if you do.
Use proper ventilation when you weld. Harmful fumes are generated,
and you need ventilation.
welding, then practice more
When you are ready to start, practice welding on scrap metal that is
close to the thickness of the metal you are going to repair. This is usually 20
or 22 gauge “stock material” which is available at metal scrap yards.
In welding, practice is essential and it will show up in your final effort.
You definitely want your technique in place before you weld a live project on
valuable metals, a car, or other items.
A MIG welder has two cables. One is the ground. It looks like an alligator
toothed clamp – like car “jumper cables”. This lead must be attached either to
the metal you intend to weld, or near the piece you are welding for proper
The other lead from the MIG welder has the electrode and its handle with the
“welder on” and wire feed button. The tip will have a gas outlet if your MIG
When you press the button, wire (and gas, with a MIG with tanks) will be fed
from a spool in the machine through the feed line and to the handle you hold in
your hand and, as importantly - electricity will flow from that electrode.
A MIG with a tank attachment will force CO2/Argon into the arc as the weld
is created. This gas helps keep the air surrounding the weld uniform, creating a
better weld in the process. A gasless mig welder uses a shielded wire electrode.
The outer coating of this shielded wire creates its own gas as it burns in much
the same way a tank provides a gas source.
Electricity travels most efficiently through clean metal, so preparing the
surface to weld is as important as the weld itself. Cut out all the rust and use
a wire brush to clean all the surfaces. Use a welding primer if necessary.
First, the procedure is pretty simple - when you press the switch on the
handle, you will strike an arc—an electrical contact—between the metal and the
electrode. Start the arc by holding the electrode 1/8" from the welding surface.
Once the arc is lit, the metal gets molten hot. New metal is fed from the
electrode, and a puddle forms on the work pieces. This puddle is molten steel.
When you weld, you are joining metals within this puddle. It all boils down to
how well you can control that puddle.
When you strike the arc, the hooded shield that protects your eyes must be
in place or you won’t see a thing.
The bright light will not only hurt your eyes, it could cause more permanent
eye damage. Practice pulling the welding hood into place until you’re
comfortable. Eye protection is imperative. You can also hold the electrode in
place, pull on the hood, and then start the arc. Whatever you want to do is
fine, so long as your eyes are covered when you start welding. You will see
everything as you weld even though you can’t see through the shield under
It’s easier to weld in short
runs—generally in about 1/8" spots.
by doing one in the middle of the entire length.
Then, tack each end. Eyeball
a spot between the middle spot weld and the end. Do the other direction
likewise. This is called stitching. It helps you make a straight weld.
Do this until you have a
line of spots from one end to the other. Don't concentrate too much heat in
one spot. Let the entire work piece cool after stitching.
Spot or Tack Welding: To create a tack, hold the electrode
in an area for no more than a couple of seconds. Hold tip in one spot about 1/8"
above the metal. Too long will burn a hole in metal. Proceed to next position
for the next tack or spot, on and on. Spot and tack welding can be done on a
seam or though holes made in the overlaid stock to be attached.
Creating A Seam or Butt Weld: When you are doing long
seams, your hand motion will be in small oval movements. These movements are
small circular motions away from you one side on the work piece and toward you
on the other. Remember that you are actually moving a molten puddle of metal
along a predetermined path. Think of it a “fanning or pulling a drop of water” –
it’s pretty much the same principle. Keep repeating this motion into the joining
metals about 1/8" to 3/16" from the top of previous circular always working
toward your standing position. Never do this type weld without tacking the
entire length with spots no more than 6" apart maximum.
Mig Welding Feed Rate & Voltage
Once the work material and wire type etc has been fixed you have three
Wire feed rate
Tip movement rate
The three interact and there will be combinations that work -- and those
The voltage setting is the main control for penetration but the other
two parameters have some effect. The feed rate sets the arc length. Your
movement controls the smooth transfer on metal to the work piece.
The first two parameters are a compromise because the ideal “settings” will
usually vary from part of the weld to another. You can vary your motion to
compensate to some extent. Low voltage will mean low penetration and the weld
will sit on the job instead of soaking in. Too much voltage will mean
penetrating right through and making a hole.
Most MIG welders have little choice of voltage, so try as many as you can.
Having fixed the voltage we now adjust the feed rate. The easiest is to drag the
gun along some scrap of similar thickness to the work piece and adjust till you
get a smooth arc. If you can hear it - you don't even need to watch it.
Start fast and slow it down. When the rate is fast you get a series of pops.
The wire hits the job and short-circuits without maintaining an arc. The wire
then melts and the process repeats when the new piece hits the metal. It doesn't
seem to do any harm.
There will be a range of speeds were you have a steady arc. You will have to
experiment a bit.