I'm no welder, but I do weld... I'll tell you this- if you are trying to fill holes that were created by rust, the surrounding metal that you are trying to plug is so thin that it won't matter what size wire you are using. Better to cut the metal out until you get to thick metal, and weld a small piece in to replace the rotted area.
When I need to fill metal in between my spot welds on patch panels, where I am dealing with some thin original metal, I'll turn up the wire speed and turn down the power. The best thing you can do to try to weld holes, provided you can get in behind the panel, IMHO, is to get a piece of sheet copper and wrap it around a body working dolly and hold it right up against the back of your holes, and then weld the hole. Just like Mark said. The weld won't stick to the copper, and it will also work like a heat sink to help the original metal from melting so easily.
Welding with 110v is harder than welding with 220v, in my opinion. I have used .023, .025, and .030 wire in the limited sheet metal welding that I have done, and have actually found that .030 worked best to produce the best spot welds, but I am welding with shielding gas and an infinitely adjustable welder.
I'm still learning.
Last edited by Norcal Dave; 06/06/2017 6:40 AM.
