Stick Welding with a Mig welder?
There are lots of multi process mig welders on the market today that are also capable of Stick and lift arc TIG. Some companies are even introducing these machines with high frequency start but that is a pretty new thing at the time of me writing this. (8-25-15).
This Lincoln electric powermig 210mp will burn a 1/8" (3.2mm) 7018 at 140 amps all day.
In the construction trades, 7018 rods are a staple.
When I worked as a pipe fitter/welder, I also welded lots of structural stuff made of heavy plate, wide flange beams, and even pipe to plate.
Most of what I welded was done using 1/8" (3.2mm) 7018 rods.
Occasionally, I would use bigger rods, but more often than not, it was 1/8" 7018...even on 2 inch thick steel.
Thats why I say, that if a machine will burn a 1/8" 7018 rod at 140 amps, you are not really limited on the thickness it can weld.
I know I am repeating myself here because I have already mentioned the term "CLAMS" many times as a way to remember the important things to help you get better at stick/arc welding.
But here goes anyway.
C stands for Current..thats amperage. As a general rule, you will want to set the machine amperage hot enough that the rod will not stick when you hold a tight arc length
L stands for Length of Arc. Hold a tight arc
A stands for Angle. Fortunately Stick welding is fairly forgiving on rod angle.
M stands for Manipulation of the electrode... there are lots of different rods and applications where some electrode manipulation is required. But welding flat or horizontal using a 7018 generally does not require any manipulation other than dragging it at the right speed...
S is for Speed...travel speed. rule of thumb is to travel slow enough to avoid undercut..but fast enough to avoid excessive build up.
Welding machines and technology have changed quite a lot in the last 35 years.
But the fundamentals of welding have not.
These tips are just as good now as they were when I was in welding school.