Measuring Sensitivity and Accuracy of Verier Type Caliper Gages

The measuring sensitivity of vernier type caliper gages may be evaluated on the basis of their capacity to associate the gaging position of the jaws with the scale graduation that is in correspondence with the actual size of the dimension to be measured. Slide position reference marks , by being scribed on a beveled surface of the slide window , will end at essentially equal level with the beam graduations., thereby reducing the incidence of parallax errors.
With few exceptions , all caliper gages used in industry have vernier graduations for reference marks on their slides. While the basic graduation of the beam is 1/20th or 1/40th of an inch(0.05 and 0.025 inch , respectively), the 50 or 25 graduation lines of the vernier , in effect , subdivide the individual beam graduations , resulting in an indirect readout resolution of 1/1000th of an inch(0.001inch).