A Brief History of Vernier Calipers
From China to France
The first caliper was found in a wreck off the Italian coast called the Greek Giglio wreck. The ship found in the wreck was thought to have been from the 6th century. So it seems that the Greeks and the Romans used calipers for measurement.
Calipers were known to have been used in china during the Han Dynasty (202BC-220AD). These Chinese calipers were made of bronze and had the manufacturing date engraved on each caliper.
Early calipers were not only used for precise measurements of objects but also were used by Europeans to calculate direction as a compass.
Pierre Vernier, born in 1580 in the Ornana, Franche-Comte in the Spanish Hapsburgs (now France) invented the "graduated caliper."
He created the Vernier scale that was published in 1631 in his publication "La construction, visage, et les proprietes fue quadrant nouvea de mathmatiques"
Jerome Lalande changed the scale to the Vernier scale during the beginning of the 19th century which took hold and remained for many years.
The modern caliper was manufactured and mass produced by an American, Joseph R Brown, in 1851 that made calipers available to machinist of all income brackets.
What is the Vernier Scale?
The Vernier Scale consists of quadrants with the primary scale in half degrees. Pierre attached a movable jaw to a fixed jaw, where the movable jaw was connected to the graduated scale.
This scale was thirty one and one half degrees in length and divided into three equal parts. Each part was one half a degree plus one minute.
Different Types of Calipers
Inside Caliper- Measures the inside of an object.
Outside Caliper- measures the outside of an object.
Vernier Caliper- Has a calibrated fixed jaw and a non-fixed jaw that slides on a Vernier scale.
Dial Caliper-Same as the Vernier except reads final fraction of millimeter or inch amounts on a simple dial. The dial caliper can be locked with a lever for a go/no go option.
Digital Caliper-Has an electronic display that displays the measurement in millimeters or inches.
Micrometer Caliper-A smaller caliper made for very small measurements.
Notes on Use of Calipers
The force exerted on the object being measured is elastic so the person using the caliper must exert a constant firm force while taking the measurement.
You need to ensure that when the calipers jaws are closed that the caliper scale reading is at zero, if the reading is not at zero calibration is required.
You can also use zero error to maintian an actual reading of the scale is the caliper is not zeroed properly.
One would use the following equation to determine the actual reading:
actual reading=main scale measurement+Vernier scale measurement-(zero error)
There are two different zero errors that can be used in this equation.
Positive (+) zero error = any measurement above zero at closed jaw.
Negative (-) zero error = any measurement below zero at closed jaw.
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