Hey guys, First post here
Just wanted to mention another welding tidbit in regards to polarity settings. When you run a FCAW (flux core) setup, you will run on what is called DC straight polarity (a.k.a. DC negative). When running a GMAW (MIG/Metal Inert Gas) setup, you will run DC reverse polarity (a.k.a. DC positive).
An easy way to think of the two is this:
DC(-) Straight = more heat in the base metal (the metal melts faster)
DC(+) Reverse = more heat in the wire (the wire melts faster)
That should give a good indication as to what the best sheet metal setup is. You can use FCAW, but you will melt your sheet metal fast, which isn't really what you want. Heat equals distortion, which is why professionals use MIG. Less heat on the sheet metal equals less distortion.
Bottom line with sheet metal is go slow and keep heat to a minimum. Continuous welds longer than 1/2" is a no-no without some serious bracing for distortion control.
All you guys welding metal 1/8" and thicker, like frame rails, sub frames, or engine mounts, by all means use flux core. Just try your best to watch your molten puddle and keep it clean. Trapped slag, and porosity (tiny holes in your weld caused mostly by dirty base metal, trying to weld over paint, etc.) means a weak joint.
Hope everyone found my first post useful!
-Avi