There are 2 basic methods to mig welding large gaps the first is to use filler metal to help cover the gap that is cut to size to fill the gap and help make the weld a smoother process.
How to close gaps welding sheet metal.
Caron first addresses why you should avoid g.
When mig welding a patch panel on your car body panels you should think of leaving small gaps between the patch panel and the original metal.
Using flux core welding to close big gaps duration.
Butt welding sheet metal with a mig welder duration.
Have you ever welded something so thin and worn out that all you do is blow holes in it.
Did you want to learn how to work around that and deliver a solid re.
Got big gaps or holes in your project.
During the welding process the metal will get hot and the gap a welder leaves will compensate for the expansion that occurs.
How to fill holes and big gaps with your mig welder is a video about welding big gaps and holes on decorative metalwork by mitchell dillman http mitchelldi.
The second is to do a root pass to fill the bottom of the gap and using stringer beads to fill the gap.
Close them up with your flux core or stick welder using this method.