verniercaliper

The vernier caliper, sometimes written as vernier caliper, is a precision measuring instrument used to determine linear dimensions with higher resolution than a standard ruler. It consists of a rigid beam with a fixed main scale and a sliding, graduated vernier scale that carries the movable jaws. The tool typically provides jaws for external measurements, jaws for internal measurements, and a depth-measuring rod. Calipers are commonly made of stainless steel or alloy and are produced in metric (millimeters) and imperial (inches) versions.

Measurement principle and readout: The vernier scale slides along the main scale, and the measurement is read by noting where the zero of the vernier aligns on the main scale and which vernier line lines up best with a main-scale line. The sum of the main-scale reading and the vernier-scale reading gives the dimension. The least count, or the smallest resolvable increment, is the difference between one main-scale division and one vernier-scale division; typical values are about 0.02 mm in metric versions or 0.001 inch in imperial versions.

Uses and variations: External measurements are taken with the external jaws, internal measurements with the internal jaws, and depths with the depth rod extending from the end of the tool. Proper technique includes zeroing the instrument, avoiding excessive force, and ensuring proper alignment to minimize parallax and indentation errors. Vernier calipers may be purely analog or have digital readouts; digital variants provide direct numerical displays while retaining the same measurement principles.

Accuracy and care: Precision depends on scale quality, calibration, and operator technique. Regular calibration, clean jaws, and correct storage help maintain accuracy for routine dimensional work.