jr is right ARc welders use a rod in the clamp, grinding will help keep the joints uniform, but light rust/scale is not an issue, I would not weld through rust if its more than spotty.. often you can wire wheel light rust, this is easier and uses less "blades" as the wire wheels last darn near forever.
you may want to get a welding book on arc as there are ARC cutting rods commonly available, and they make for seriously dangerous welds. I believe the 60xx as are 70xx (60=60000 psi and 70=70,000 psi fillers I'm 98 percent sure of those 2, as I use them regularly for joining) are welding rods but you really need to read up find a chart somewhere to ID your best size and number for your project.
the extra rod methods are tig, brazing, and solder.