Terminology and History of Calipers
– Caliper is the American spelling, while calliper is the British spelling.
– A single tool might be referred to as a caliper or as calipers — a plural only form.
– Colloquially, the phrase pair of verniers or just vernier might refer to a vernier caliper.
– In loose colloquial usage, these phrases may also refer to other kinds of calipers.
– In machine-shop usage, the term caliper is often used in contradistinction to micrometer.
– The earliest caliper has been found in the Greek Giglio wreck near the Italian coast.
– Calipers remained in use by the Greeks and Romans.
– A bronze caliper, dating from 9 AD, was used for minute measurements during the Chinese Xin dynasty.
– The modern vernier caliper was invented by Pierre Vernier.
– The vernier caliper was an improvement of the nonius of Pedro Nunes.
Types of Calipers
– Inside calipers are used to measure the internal size of an object.
– Outside calipers are used to measure the external size of an object.
– Divider calipers, popularly called a compass, are used to mark out locations.
– Oddleg calipers, also known as Hermaphrodite calipers or Oddleg Jennys, are used to scribe a line at a set distance from the edge of a workpiece.
– Vernier calipers have various jaws and scales for measuring different dimensions.
Inside Calipers
– Inside calipers require manual adjustment prior to fitting.
– Fine setting of this caliper type is performed by tapping the caliper legs lightly on a handy surface.
– A light push against the resistance of the central pivot screw then spreads the legs to the correct dimension.
– The upper caliper in the image requires manual adjustment, while the lower caliper has an adjusting screw.
– Inside calipers are used to measure the internal size of an object.
Vernier Calipers
– Vernier calipers have outside large jaws for measuring external diameter or width of an object.
– They also have inside small jaws for measuring the internal diameter of an object.
– A depth probe/rod is used to measure depths of an object or a hole.
– Vernier calipers have a main scale marked in millimeters and inches.
– They also have a vernier scale that gives interpolated measurements to 0.1mm or fractions of an inch.
– Vernier, dial, and digital calipers directly read distance measurements with high accuracy and precision.
– Vernier calipers have a calibrated scale with a fixed jaw and a sliding jaw with a pointer.
– The distance between the jaws is read by interpolating the position of the pointer on the scale.
– Vernier calipers can measure internal and external dimensions, as well as depth using a probe.
– Vernier calipers commonly provide a precision of 0.01mm (10 micrometers) or one thousandth of an inch.
– Vernier calipers can be used to measure external distances.
– They can also measure internal distances using the uppermost jaws.
– The depth of a step or hole can be measured with the depth probe.
– The width of a step can be measured using the top of the calipers.
– Vernier calipers can be used for marking set or measured distances from an edge.
Dial and Digital Calipers
– Dial calipers read the final fraction of a millimeter or inch on a simple dial.
– They use a small rack and pinion to drive a pointer on a circular dial.
– Dial calipers allow for direct reading without the need for a vernier scale.
– The slide of a dial caliper can be locked at a setting for simple go/no-go checks.
– Dial calipers can be used for differential measurements and setting the dial using a master object.
– Digital calipers use a linear encoder instead of a rack and pinion.
– They have a liquid-crystal display that shows the measurement in different units.
– Digital calipers can switch between millimeters and fractional or decimal inches.
– They provide the option to zero the display at any point along the slide.
– Some digital calipers have a reading hold feature for measurements in awkward locations.
– Ordinary 150mm (6in) digital calipers have a rated accuracy of 0.02mm (0.001in) and a resolution of 0.01mm (0.0005in).
– Longer calipers have slightly lower accuracy, with 0.03mm (0.001in) for 100-200mm (4-8in) measurements and 0.04mm (0.0015in) for 200-300mm (8-12in) measurements.
– Digital calipers can contain capacitive, inductive, or magnetic linear encoders for measurement.
– Some digital calipers offer serial data output for direct data entry into digital recorders or software.
Note: The remaining content does not fit into any of the comprehensive groups provided. Source: https://en.wikipedia.org/wiki/Calipers
Caliper(s) or calliper(s) are an instrument used to measure the dimensions of an object; namely, the diameter or depth of a hole. The word “Caliper” comes from latin roots meaning precise pincer. The least count of vernier caliper is 0.1 mm.
Many types of calipers permit reading out a measurement on a ruled scale, a dial, or an electronic digital display. A common association is to calipers using a sliding vernier scale.
Some calipers can be as simple as a compass with inward or outward-facing points, but with no scale (measurement indication). The tips of the caliper are adjusted to fit across the points to be measured, and then kept at that span while moved to separate measuring device, such as a ruler.
Calipers are used in many fields such as mechanical engineering, metalworking, forestry, woodworking, science and medicine.
