What I said upstairs is too strict. L aluminum plate and stainless steel plate are polished with 46# white steel grinding wheel with good finish. Aluminum plate and stainless steel can be oiled. As long as the aluminum plate is fixed, grind it as you want. I suggest you make a long stainless steel jig mill (at least after grinding flatness, it is absolutely possible, and deformation is not afraid to take it down and knock it over with a tungsten steel bar). I have been grinding it for some time.