Multi-proportion dividers

Abstract

The invention relates to a pair of multi-proportion dividers. According to the pair of multi-proportion dividers, the midpoint of a straight line or a circle center with the straight line as the diameter can be rapidly and accurately found, and drawings of corresponding proportions can be rapidly and accurately completed without the operation of proportion multiplication and division. According to the technical scheme, a plurality of constant-proportion holes are formed between a divider needle of one divider leg and a pencil lead of the other divider leg, the distance ratios of the constant-proportion holes to the two top ends of the divider legs are 2:1, 2.5:1, 4:1 and 5:1 respectively, pin sliding grooves are formed between the constant-proportion holes, the width of the pin sliding grooves is smaller than the diameter of the constant-proportion holes, connecting devices penetrate through the corresponding constant-proportion holes in the two divider legs to form hinge joint so as to connecting the two divider legs, and during working, the plane side of a half ball of the convex connecting device and the plane side of a half ball of the concave connecting device are attached to form a spherical shape. The pair of multi-proportion dividers is suitable for drawing teaching and drawing in schools, and also suitable for workers in enterprises and public institutions for drawing.

Description

technical field [0001] The invention relates to a compass, in particular to a dobby compass. Background technique [0002] In the teaching process of drawing or drawing courses, compasses are an essential tool for drawing circles or arcs, and are often used for drawing with rulers and compasses. However, in the drawing process, the problem of how to determine the midpoint of an existing straight line is often encountered. In the known technology, there are two ways: 1. First measure the length of this line segment, then divide by 2, and then use the existing The end of the line segment is used as the reference to measure to obtain the midpoint; this method needs to measure the size twice, and the accuracy of the measurement depends on the accuracy of the measuring tool used. The accuracy of the method is as accurate as millimeters, and each measurement will produce an error of less than 1 millimeter. In addition, the operation of dividing by 2 is performed in the middle, so...

AI Technical Summary

Problems solved by technology

However, in the drawing process, the problem of how to determine the midpoint of an existing straight line is often encountered. In the known technology, there are two ways: 1. First measure the length of this line segment, then divide by 2, and then use the existing The end of the line segment is used as the reference to measure to obtain the midpoint; this method needs to measure the size twice, and the accuracy of the measurement depends on the accuracy of the measuring tool used. The accuracy is as accurate as millimeters, and each measurement will produce an error of less than 1 millimeter. In addition, the operation of dividing by 2 is performed in the middle, so this method is not accurate, and it is energy-consuming and time-consuming.

2. It is necessary to make an auxiliary line. Use the compass needle end to coincide with one end of the line segment. With the radius greater than half the length of the line segment, draw a section of arc on both sides of the line segment, and then let the needle end coincide with the other end of the line segment. Draw a section of arc on both sides of this line segment with a radius of , these four arcs form two intersection points, the intersection point connecting these two intersection points and the middle line segment is the midpoint of this line segment; this method has more steps, and the more steps The more the more, the more time-consuming, and the more steps there are, the greater the accumulated error will be. When drawing, only the midpoint of this straight line is needed, and these four auxiliary arcs need to be erased after finding the midpoint, which is troublesome and time-consuming , and sometimes it is not erased cleanly, which makes the whole drawing messy. In addition, when drawing the first two arcs, because you don’t know where the intersection with the next two arcs is, if the drawn arc is short, it will When the latter two arcs may not form two intersections, it is necessary to go back and redraw the first two arcs. If the first two arcs are drawn long, to increase the success rate of intersecting with the latter two arcs, That increases the workload for the subsequent erasing work. It can be seen that this method is time-consuming, laborious, and low-precision; when using proportional drawing, it is necessary to multiply the scale or divide the scale on the basis of the dimension. When using a ratio of 1:2.5 for drawing, it is necessary to divide the original dimension by 2.5, which is time-consuming and laborious, and sometimes an approximate operation of rounding is required, which reduces the accuracy of drawing

[0003] In the process of drawing, these problems often appear: 1. An existing straight line is the diameter of the circle to be drawn. How to quickly and accurately find the center of the circle without measuring the length

2. Knowing a straight line, how to quickly and accurately find the midpoint without measuring the length

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