A welder once told me that a bad looking weld is just that, bad.
A truer statment has never been said!
now for the confusion
A bad looking weld is bad, but, may work.
a good looking weld isn't neccessarily a good weld! (I have seen some doosy's!)
This is not a Spec anywhere that I know but the weld should be as thick as the wall that is being welded (this is the eyeballers rule of thumb! ) so .120 tubing should have a 1/8 (minimum) weld going around it.
just for and example I knew this guy that could weld the prettiest nicest looking evenly spaced weld you ever saw, but he wouldn't weld bigger than 1/8" so all his welds were very strong in 1/8" and under material. Not so much on the 1/2" plate (if you know what I mean)
Tube are hard to weld follow Rcazwillis's advice start with flat plate and work up. Practice makes perfect! or more precisely perfect practice makes perfect!
thanks
Michael T.
"If you don't stand for something, chances are, you'll fall for anything!"