Method and apparatus for dimensional gaging with fluid pressure

An air pressure gaging apparatus for indicating a digital representation of a dimension of a workpiece surface, said apparatus comprising:

• an air pressure regulator having an input and an output, said regulator adapted to receive pressurized air at the input and to provide air at a fixed, regulated pressure at the output;
• gage tooling including at least one air jet formed in said gage tooling and directed at the workpiece surface;
• a conduit connecting the output of the regulator with the gage tooling, said gage tooling providing an air back pressure in the conduit which varies with the distance between the air jet and the workpiece surface;
• means for generating a digital representation indicating the air pressure in the conduit intermediate the regulator and the gage tooling as an indication of the dimension of the workpiece surface, said indicating means including a transducer coupled to the conduit at a first location and a digital display device coupled to the transducer for generating a digital representation of the dimension of the workpiece surface;
• a first variable conduit restriction for adjusting the air pressure displayed on the indicating means, said first restriction coupled to the conduit in a series connection between the regulator and the first location;
• and
• a second variable conduit restriction for adjusting the air pressure displayed on the indicating means, said second restriction located along the conduit in a series connection between the first location and the tooling, whereby the first and second variable conduit restrictions may be adjusted to adjust the indication on the indicating means.