The next consideration will be what size gas bottle to get. The 2 ft tall (
60 cubic foot?) bottles are less expensive to purchase but more expensive to
refill and have the hassle of running out of gas in the middle of a project.
Running the numbers for the break-even point will tell the tale.
I am using a 4 ft tall ( 125 Cubic Foot?, ~ 40.00 to fill ) bottle with good
results. How long will it last? I'm putting a rollcage in a fullsized GM
car and it looks like one bottle will do the trick.
During a trip to a local scrap metal yard I found a 2 ft tall bottle and have
it in reserve if the main bottle runs out during a project.
If you purchase a cylinder you generally have the option of having yours
refilled or trading it in for a used full one. Consider the cylinder
purchase price a deposit and not a purchase. Cylinders with the welding gas
company name are maintained by the company. ( Valve replacement, hydrostatic
testing). The bottles last a very long time, I've had some oxygen bottles
from the 1920's and the oldest one I've had was 1918!
Argon CO2 mix is generally used for steel welding as it provides a smooth
weld. The steel must be rust free and clean of oil, paint and such.
You can also use straight CO2 but the weld will look rough and the spatter is
increased. I use a standard 2 ft tall soda pop machine bottle for this task.
When I'm welding steel over 3/8 thick or welding thick rusty metal CO2 seems
to burn deeper and blow the rust away.
I will not attempt to weld rusty metal with CO2 if the joint is extremely
stressed or the visual quality of the weld is a factor. For fence posts or a
trailer to pull around the garden, CO2 provides low cost ( 7.50 last fill)
Straight argon is used to MIG weld aluminum. I've only done this a few times
and aluminum welding is much different than steel. It is difficult to judge
when the puddle is too cold or hot. Tig welding is probably the way to go
but require a different machine.
Harold
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