Need help polishing Stainless Steel

180 grit and working it in progressive steps of no more than 60 grit at a time until around 400 grit but you must sand to the bottom of the previous grit or scratches will appear during the buffing procedure and or distort the finsh . As far as buffing there is two steps cutting and coloring you want to use a ventalated cotton buff with an aggresive Tripoli cutting compond then use a cotton flannel wheel with a white coloring compound. You dont say how large thes parts are but im not sure if your bench grinder will be capable to generate enough speed or have enough power i run a 5 Hp polishing machine with a 10-12" dia wheel and two pair of gloves on each hand the parts become very hot and can burn your hands now im not talking about small thin pieces but larger 16 gauge and up in thickness and larger parts you find on cars and bikes. Good luck