Different grades of surface plates
Surface plates . the constructional features of surface pkates . application of different grades of surface plates . specify surface plates and the constructional features and uses of marking tables Surface plates-their necessity When accurate dimensional features are to be marked, it is essential to have a datum with a perfectly flat surface. Marking using datum surfaces which are not perfectly flat will result in dimensional inaccuracies. The most widely used datum surfaces in machine shop work are the surface plates and marking tables. Materials and construction Surface plates are generally made of good quality cast iron which are stress relieved to prevent distortion. The work surface is machined and scraped. The under side is heavily ribbed to provide rigidity. For the purpose of steadiness and convenience in levelling, a thress point suspension. Smaller surface plates are placed on benches while the larger surface plates are placed on stands. Other materials used Gran...