@Pᴀᴜʟsᴛᴇʀ2 it seems I wasn't the only one to blame for the bad welds, I examined my grounding clamp and this is what I've found. I'll try to cut it shorter and remake the conection

I hope this makes the next welds easier because shit, right now it's a PITA to get anything half decent. I can make some spot welds on the sheet but butt welds burn through all the time. It might be partially because of the bad grounding, but I'm also thinking about laying some pieces of wire between the butt welds so I have more material there to avoid burning through