The grinding wheel R angle of surface grinder is not more than 1/4R and less than 0.2r. According to relevant public information, the center of the R-angle dresser is relatively high, and the internal arc trimmed on a grinding wheel is generally not more than 1/4R and less than 0.2r.. Arc repair is usually divided into rough repair and fine repair. Like the pad gauge, the pad gauge is generally 0.0 1 larger than the actual pad.