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Types of Rulers


Caliper

Instrument used to measure the distance between two symmetrically opposite sides. The caliper works by sliding a rod over a toothed part and allows thickness readings through a vernier scale or a digital reader. The vernier is the measuring scale located on the movable side of the caliper. This scale provides decimal precision by aligning it with a measurement on the ruler. Calipers are made of plastic with a metal rod or entirely of stainless steel. Their graduations are calibrated at 20 °C.

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Micrometer

The micrometer works through a micrometric screw and is more precise than the caliper.

Scale Ruler

The scale ruler is an instrument shaped like a triangular prism that has six rulers with different scales. It is used to measure and make drawings in enlarged or reduced scales.

Protractor

A protractor is a tool with a circular scale, or sections of a circle, divided and marked in regularly spaced angles, similar to a ruler. Its use is diverse, applied in education, mathematics, engineering, surveying, construction, and various other activities that require accurate angle measurement. The protractor is the instrument we use to measure the amplitude of an angle. The most commonly used unit of angle measurement is the degree. One degree is the smallest division found on a protractor.

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Slide Rule

A slide rule is an analog mechanical device that allows calculations to be performed using sliding graduated guides. Despite its similarity to a ruler, the slide rule has nothing to do with measuring small distances or drawing straight lines. The slide rule is the precursor of modern electronic calculators.

T-Square

The T-square is a tool specifically for technical drawing. Just like the parallel ruler, it is used to support a set square or to draw parallel lines when placed against a drawing table. It is usually around 80 cm long and is typically made of wood with acrylic details.

Astrolabe

The astrolabe is an ancient naval instrument used to measure the altitude of stars above the horizon. Handling the astrolabe required two people: one would hold the astrolabe at eye level, aligning the ruler with the sun, while the other would read the degrees marked on the circle. The astrolabe consisted of a large circle, inside which ran a ruler.