with 0.035 solid wire, 75/25 argon/co2 it claims to be able to weld 3/8" in a single pass, but multi-passes and special technique may be required for certain joint designs.
when i was looking for welders one thing i would do is look at the manual and find the chart that tells which settings to use, looking at that chart can give you a good idea of what to expect. from looking at that the 210 can do 1/4" no problem, but the 187 may have a bit of trouble with 1/4" (even though the 210 is advertised to weld 3/8", and the 187 is advertised to weld 5/16")
tell you the truth, i would have considered the 140 much more, but it can only weld 1/4" with flux core wire and multi passes, so it would be a pain to weld 1/4", and sometimes you can't really use multi-passes.
i just did some more welding, tried some more 1/4", 14ga, and 1/8" it did amazing on the 1/8" and 14ga, looking like i welded on both sides with a huge signature, a decent bead, and you could tell the bead had melted into the base metal. it also did the 1/4" great, just like the pics i posted. as usual the flux core wire makes a good bead a bit more difficult, can't wait to get a gas bottle!
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torque ranger, i am familiar with that technique and i agree it works nicely for
thin sheet, but how exactly is mentioning that relevant? are you talking about the 14ga tube? i wouldn't consider 14ga thin enough to want to use the technique you mentioned, are you suggesting i may help with the burn though? all i need to stop that is pick up my travel speed. i'm running 230v
EDIT: i called the guy who asked about my welder, he is coming tomorrow at 10:00 AM, hope fully i can get the price i'm asking (which is already pretty low!)
maybe i will go get some pics of what i did yesterday (too hot today almost 90 degrease F, and almost 90 percent humidity! 
)
, my new welder! 
