I fought undercut on my 2G root passes for three weeks straight until my buddy in Gary told me to bump my travel speed up a hair and now my caps come out clean.
Man, it's always the guy two states over who fixes your welds with one sentence, right? Travel speed is one of those things nobody explains good in school, they just yell at you to slow down. Turns out sometimes faster is the whole answer and your hands just gotta catch up to your brain. Three weeks of fighting undercut for a one line fix from Gary is rough but hey, clean caps are clean caps.