not exactly right. the first is an abrasive disc. that's the right guy for steel, but doesn't work great in aluminum because its very sticky and melty. the thir

not exactly right. the first is an abrasive disc. that's the right guy for steel, but doesn't work great in aluminum because its very sticky and melty. the third is a metal skill saw blade. I really wouldn't use this with steel at all, but you definitely want to cut aluminum and not grind it. the tool I would normally use for this is a portable bandsaw, with speed control that you would set high for Al and low for steel, probably pretty close to the skill saw.