When the bottles are supplied they will have a small plastic cap that is pushed into the threads of the
fitting. This is to stop any foreign particles from getting in there during storage and transport before you
get the bottle. In Australia we have these little pesky mud wasps that will build their mud nests in any little
hole, crack or crevice. And they always make them where you don't want them to.
Gas regulator and welding bottle
To remove the plastic cap crack open the bottle by turning the valve / tap on. The plastic cap under high
pressure will shoot off out of there real quick. So make sure it's not pointing at you, aim it at someone
else:)
Now check your gas regulator to make sure that it is all in good shape. Look at the rubber O-ring on the
shaft /threaded area and check that there are no cracks in it and that it looks like it will make a positive
seal. Then all you have to do is basically screw the threaded part of the regulator into the female part of the
gas bottle. Through in the nut as far as you can with your fingers, and then take a shifter or open ended
spanner and tighten up the fitting.
If you haven't already done so you're also going to need to hook up the gas line that goes from the
regulator into the back of the mig welding machine. These are usually held in place with some of those
ratcheting hose clamp fittings. These can be tightened up using a screwdriver or a socket.
Turn main gas valve on
Now that you have fitted your gas welding regulator to the shielding gas bottle you can slowly open up the
valve. Open up the valve a few turns and you will notice that a gauge on the regulator will move.
Pressure gauge
The one that's going to move will be the one that displays the pressure that is inside the gas bottle.
You should take note of where the needle is on the gauge now that you have a full, brand-new bottle of gas.
This way you can work out at what reading on the gauge will be your half way mark and quarter of the way mark
til it's empty.
Flow gauge
The second gauge shows you how much gas you are flowing.
The whole idea and purpose of the welding regulator is so that you can control the flow of the gas. If you
were to just look up your welding gun straight to the gas bottle without the gas regulator, the pressure coming
out the end of the gun would have been too strong.
That is why the regulator is used to control the pressure coming out of the bottle.
Depending on the thickness of metal you are welding, the type of wire you are using and if you are welding
in windy conditions will determine how fast you need to flow your gas at.
The best way to determine how much you need to flow is to look at the manufacturer's specifications for that
particular brand of welding wire your going to use.
Manufacturers of mig welding wire especially the quality manufacturers spend a lot of time doing research
and development to make sure that their products work properly. This is why you need to read what they specify
in their sheets.
Generally speaking though if your welding mild steel using an ER70S-6 wire, which is a general purpose mig
welding wire. And if you are using a mixed gas of carbon dioxide and argon.
Your flow rate will need to be from about 12 L per minute up to about 20 L per minute. As you start to mig
weld you will know when you're not using enough shielding gas. When welding with higher amps and thicker plate
the gas flow will be higher. And also if you are outside and there's a bit of wind around you will need to turn
the gas up. This is because the wind from outside will tend to blow that shielding gas away from the welding
arc.
This is why sometimes people like to use a gasless self shielding mig wire as it is not affected by wind
because you don't need to use shielding gas.
Adjusting welding gas flow amount
So to adjust the gas flow rate for your mig welding gun you either twist the adjustment knob clockwise or
anticlockwise to either increase or decrease the gas flow rate.
A little tip or pointer here for you is that the only important place the
gas flow needs to be accurate is at the welding nozzle.
I have noticed with my mig welding machine that if I have set the gas flow at say 12 L per minute, when I
pull the trigger and start welding the flow rate drops slightly.
So now what I do is pull the trigger of the gun, and then adjust the regulator as the gas is flowing in real
time. This gives me a true accurate gas flow rate.
My particular machine when I pull the trigger to adjust the gas flow, it also wastes a few feet of
welding wire. Some welding machines will have what is called a gas purge button.
You press this button and it will only flow the gas not the wire as well.
You can also go and purchase a gas flow meter that slips over the end of the welding gun nozzle and has a
little ball float in it. Then when you purge the gas the ball will float and let you know exactly how much gas
you are flowing at the end of the nozzle.
In part 8 of how to mig weld we go over the different welding modes or settings
of a basic mig welding machine.