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The general length measurement tool is a ruler, which can solve the measurement of most regular objects. However, for curved corners and other shapes, the steel tape measure is not easy to fold and is flexible and easy to stretch, and cannot fit the surface of the object well. The circular ruler changes from straight to curved and extends infinitely, breaking through the limitations of traditional rulers and allowing for special-shaped measurements. The ring ruler uses the principle of constant radius of a circle to convert curved surface measurement into the length of a circle rolling along the surface of an object, which is full of creativity.
The ring ruler has a three-in-one hamburger structure. The upper and lower layers are hand-held bases, which are equivalent to the rotating axis, that is, the "stator"; sandwiched in the middle is a rotating measuring ring, which is the "rotor". The structure is ingenious. .
When using it, pinch the upper and lower layers with your thumb and index finger, press it slightly against the surface of the object being measured, push the ring ruler forward, and the rotor will roll, always keeping the circumference tangent to the object being measured, that is, point contact. The length rolled is the arc length of the object being measured.
There is a data reading window on one side of the stator, and the internal scale is integrated with the rotor. The stator is relatively stationary, and the distance the rotor has rolled is displayed through the scale, which is scientific and reasonable.
The dynamic picture below shows the measurement process of the ring ruler. During the rotation, the scale moves along with the circle. The cross-sectional circumference of the stick is 8.7 cm, which is really convenient and fast.
But the circumference of the ring ruler is only 10 centimeters. How to measure longer items? Beidou came up with a good idea: at the 0 mark, an elastic groove is designed inside. Every time the 0 mark is passed, there will be a "click" and a slight vibration. The number of times 0 is passed is recorded in the mind, which is a multiple of 10 centimeters. , clever solution.
Let’s briefly introduce the measurement method: first reset the reading to zero, and place the zero mark perpendicular to the starting point of the measurement surface. Roll along the measurement path, and you will feel a vibration and crisp "click" sound every time you turn. When reaching the measurement end point, align the arc ruler vertically with the measurement surface and read the value. So the total length is the number of rolling turns times 10cm plus the end point reading. For example: the end point reading is 8.2, after rolling three times, the total distance is 8.2+ 310= 38.2cm. There are many pain point problems encountered in daily life, which are difficult for one person to complete. With a ring ruler, you can easily solve them.
In addition, what should I do if the ring ruler cannot roll in the concave 90° corner like the picture below? Everyone has studied mathematics, and they should all remember the relationship between the circumference and radius of a circle. Just leave a space for the radius.
As for tool accuracy, the diameter design error of the ring ruler does not exceed 0.005mm, and the processing accuracy of Beidou is less than 0.001mm. One measurement rotation is 10 centimeters, and the error does not exceed the diameter of a hair. Whether the measurement is accurate depends on personal techniques. Errors caused by human factors cannot be relied on Beidou. If you have high requirements for measurement results, it is recommended to use professional measuring tools.
