Sounds like CK is going to get you squared away, that's excellent. I've only been TIG welding for a few years, so take my advice for what it's worth, which is about zero! My machine is maxed out at around 200A, and I mainly use it on .125" or thinner material, but occasionally up to .250". I'd say 75% of the time, the torch has a #8 Furick cup w/gas lens and 3/32" electrode. It's fine on steel or aluminum. If doing stainless or chrome moly, I go to a larger cup, especially on stainless, or joints that require a lot of electrode stick out. I often use a clear cup as I like them, but they are extremely fragile.