I wouldn't get anywhere close to a sheet metal weld with any full size grinder. Angle die grinder with a 3M Roloc Cubitron disc, first with 36 grit, finished up with 80 grit Cubitron. Tight spots get a mini belt sander. DA with 40-60 grit for a nice finish.
Attachments
modela198.jpg (30.55 KB, 175 downloads)
modela199.jpg (38.73 KB, 174 downloads)

Mark

1951 Chevy Suburban
In the Stovebolt Gallery
Lots and LOTS of pictures
Project Journal --- 10 pages worth!