Flap discs aren't really ideal for removing paint because they load up. However, a 40 grit will do better removing the bulk of the paint without loading up as bad, then come behind with an 80 to smooth the metal out a bit if you want. They do make paint removal wheels that are sort of like a real gnarly aggressive schotch-brite type material that work really good and will not remove as much metal either.
Likewise, depending on how clean your welds are, a flap wheel may not be the best tool, but rather a knotted wire wheel. They will be far more efficient at cleaning slag and small spatter bbs from the metal. If you're looking to grind welds flush or smooth ugly beads, a 40 grit will make quicker work of it, and then something finer to blend it in a bit if you so choose.
Wire brush for flux slag( fluxcore welding), a old file with teeth ground off and the tip slightly sharpened to a chisel 1-5* used as a scraper to hit the little beads off...
Oh and that is an old file with a handle attached or the pointed tang broken off... As not to jab you through the hand... When chipping...
Thx for the info, I’ll have to see what I can come up with when the time comes.
While I’m here, my dad was considering having me sandblast(or something to that effect) under his new(used) dump trailer(low profile) and coat it with the rust prevention stuff. If I used an angle grinder what would be the best to use, whether it be flap disk, scotch brite, or wire wheel?
I use the grinder/cutoff disc for the first passes after welding or other material removal. The scotch brite pads are great for old gaskets and basic cleaning. Wire brush is for more stubborn crud. Flap discs are nice but I find them with limited uses.
I would treat the paint with a gel type paint stripper, I have had incredible luck on various types of paint with it. I clean splatter off with a stout wire wheel cup, like this one, it aggressively knocks off the splatter and removes almost no base metal.