surface plate made according to sandard JB/ T7974- 99 , rib type or case type , recangle/ round surface , working surface made by skiving , groove V/ T/ U shape and hole of longround shape can be made at the surface of the plate . The surface plate is a plane standard equipment used for testing and drawing of work pieces on it , The surface plate shall be adjustable to horizontal positaion and laded evenly on each pivot , Environmental temperatire (20?5) , and vibration shall be avoided when usingType ( mm ) Precision Grade (?m)