A Brief History and Usage of Vernier Calipers
From China to France
The first caliper found was located within The "Greek Giglio Wreck," a wreck off the Italian coast. The ship found excavating the wreck was dated around the 6th century.
Romans weren't the first to use calipers. The earliest calipers were seen in China during the Han Dynasty (202BC-220AD). These Chinese calipers were made of bronze and had the manufacturing date engraved on each one.
Early calipers were not only used for precise measurements of objects but also were used by Europeans to calculate direction. They were common on almost all sea-going vessels and were used to dictate direction and to read maps.
Pierre Vernier, born in 1580 in the Ornans, Franche-Comte in the Spanish Hapsburgs (now France) invented the "graduated caliper." He created the Vernier scale, published in 1631 in his publication "La construction, visage, et les proprietes fue quadrant nouvea de mathmatiques." The Vernier scale enabled a user to obtain precise measurements of objects at a greater level of accuracy than known prior.
Jerome Lalande changed the scale to the Vernier scale during the beginning of the 19th century which took hold and remains in place today.
The modern caliper was manufactured and mass produced by an American, Joseph R Brown, in 1851. Joseph R. Browns commercial calipers made them available to machinists of all income brackets. Today you can find some sort of caliper in most people's garage.
What is the Vernier Scale?
A modern caliper has a movable jaw attached to a fixed jaw, where the movable jaw is connected to a graduated scale.
The modern vernier scale consists of quadrants, thirty-one and one-half degrees in length and divided equally, with the primary scale in half degrees. Each measurement was accurate to one-half a degree plus one minute.
Engineers, Machinists, and Auto Mechanics use Calipers in their daily tasks:
- Auto Mechanics use calipers to determine Brake Rotor thickness.
- Machinists can determine accurate outside and inside diameter measurements including proper depth of various ducts within an engine.
Different Types of Calipers
- Inside Caliper - An inside calipers measures the inside of an object. Each jaw points outwards for proper placement within an object where the measurement will be taken. Perfect for determining inside diameter and depth.
- Outside Caliper - An outside caliper measures the outside of an object. It is similar in appearance to the inside caliper yet does not have a movable jaw. Both jaws are fixed and the measurement is taken from a scale on the top of the caliper. Perfect for determining outside diameter.
- Vernier Caliper - The vernier caliper has a calibrated fixed jaw and a non-fixed jaw that slides on a Vernier scale.
- Dial Caliper - The dial caliper is the same as the vernier except it reads to a final fraction of a millimeter or inch amounts on a simple dial. It can be locked with a lever for a go or a no-go option.
- Digital Caliper- The digital caliper has an electronic display that displays measurements in millimeters or inches.
- Micrometer Caliper-The micrometer caliper is a smaller caliper made for smaller measurements. The micrometer has the appearance of a small vice that closes around an object and provides an accurate millimeter measurement.
1.) 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.
2.) You need to ensure that when the caliper's jaws are closed that the scale reading is at zero. If the reading is not at zero, calibration is required.
You can also use zero error to maintain an actual reading of the scale if the caliper is not zeroed properly. You 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.
In The Lab
To ensure proper usage of your lab calipers have your students measure a variety of different objects.
When introducing students to calipers make sure to show how to properly calibrate them before each measurement.
Make sure your students are familiar with the equation above before logging data down in their log books.
Be sure that your students are using the proper caliper for the measurements they are taking.
Have a great lab and happy measuring.
© 2013 Jamie Lee Hamann