Originally Posted by 16v4nrbrgr
Weld penetration is very important to safety and MIG has a tendency to blob crap on top of bad surface welds that protrude. Do a lot of sample welds on pieces of the same material and thickness to be welded to get the settings and technique right for full weld bead penetration, checked by inspecting the back side of the welds.
Grinding out welds also weakens them, especially if they are limited depth due to bad penetration already, a weakness of MIG because of its constant feed no matter what's going on at the puddle. Structural joints should never be ground down.
I have used the bevel edge to a v shape and butt against with another bevel edge v shape to have weld through and though. Then a grind to get flat I find acceptable.
Others mentioned about how to use a drilled through hole on one piece of metal to fill in an attach flat to another in addition to edge weld together.
Somethings can be done with tricks like this, but I may like to see what those TIGs that others got a HF do. I used a couple thousand dollar TIG machine, but just own the Hobart Auto Arc 130 run on 120 single phase. Does 1/4 inch although they say it shouldn't. Use 75 / 25 gas and like it a lot for steel.