Also one of the biggest mistakes in installing those patch panels is not removing enough of the "bad" metal. You can't weld thin rust to new metal.Doesn't work. You need a nice clean sharp edge with a nice fit up to the new panel.If you don't grind or cut the metal correctly you will end up with a edge that is cut like this / (beveled)...it should be square with thin gauge sheet steel.No gaps in the joint. Learn to tack weld first.Connect your tacks together.Start by spacing them 1" apart.Then go back and weld (tack) between them. Once your machine is set and your an expert at the tack weld....move on to a stitch weld. A row of tacks is surprisingly strong. Once connected,they are a solid weld. A whole bunch stronger than boogers and a lot eaiser to clean up......
Steve