Ever try hammer welding?

I have that and like it. Works well for grinding out spot welds and can get you back into tight areas.

i have an air version of one of those belt sanders. works very well for lots of applications.

On those little 13 inch belts, do you guys prefer 36 or 60 grit for knocking down welds?

80 grit discs seem too slow, I was thinking the belt + going more coarse would help me be more productive.

it depends a lot on the job at hand.
i use both 36 & 60 grit to rough grind, followed by the 80.

I'm not sure which grit is on there. I bought several spares but am still using the one it came with. I would think that rougher is better to remove the material fast with less heat.

what a lot of guys forget is a new belt or disc of any grit cuts faster and cooler than a used one.
don't try to use up your belt or disc just because there is some grit still there.
i save my used ones and use them up forming and polishing thick [1/8" and up] material.

That does work nice. But it always seems you have to be really fast or have 3 hands.

I have always used an air driven cut-off wheel for grinding sheet metal welds. They are available in different levels of abrasion, a gritty disc grinds pretty quickly without building up much heat.

I went and bought the air version of that mini belt sander. Works great with 36 grit.