Abstract: A method of calibrating a bore gauge comprises inserting two or more radially extendable elements of a bore gauge into a selected calibrated setting bore or groove in a setting plate comprising a plurality of calibrated setting bores or grooves, each calibrated setting bore or groove of the plurality having a different calibrated nominal diameter. A micrometer of the bore gauge is adjusted so as to cause a measured diameter of the selected calibrated setting bore or groove to match a specified nominal diameter of the selected calibrated setting bore or groove. A setting plate for calibrating a bore gauge includes a plurality of calibrated setting bores or grooves, each calibrated setting bore or groove of the plurality having a different calibrated nominal diameter.

Abstract: An automatic machine including a two-dimensional positioning table, a device for measuring the dispositions attained by the table in each of said dimensions and a tool holder having an operative center in respect to said two dimensions. Furthermore means are provided for imaging a graticule means to an operative plane of the table so that the center of said image is substantially aligned with the operative center of the tool holder. A visual input device is positioned to view a part of said operative plane including said graticule image and comprises pattern recognition apparatus for:(a) identifying a predetermined mark on a flat surface of an object carried by said table, said flat surface lying in said operative plane,(b) identifying said graticule image, and(c) measuring the separation of said mark from said graticule image center.