In the tutorial, there's a lot of discussion about grinding a V-groove on the edges of plates to be butt-welded to allow a lower current machine to weld thicker stock. For best performance on thicker stock, a root gap of about 1 mm is also recommended. I assume that this works, since it seems to be a universally accepted technique.
My question is this: WHY does it work?
My question is this: WHY does it work?