The need for long range height measurements has been around since the principles of layout work became a fundamental requirement in machine shops. The first step in the manufacturing process is to lay out a piece by transferring a design or pattern to a workpiece. The common tools for layout work include a surface plate, a surface gage with scriber or dial indicator, and a long range height gage.
As with most inspection, the surface plate provides a reference plane for the part and the height gage. Height gages are used to set and mark a certain height on the workpiece, or to measure the piece after it has been machined.