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一、用途。使用皮尺(竹尺)、垂球线(或花杆)、方向架设置平曲线肘,应用此计算盘,即可直接读出切线支距、弦线支距、弦线偏距所需数值。二、制作说明。计算盘采用两种比例尺: 1.1:500外圆半径为0.107米,内圆为0.100米。其优点是便于携带,使用率较大(弧长可达50米左右)。但精度较差可应用于平原丘陵区。 2.1:200外圆半径为0.137米,内圆为0.130米。
First, the purpose. Use the tape measure (bamboo ruler), pendent ball (or flower pole), the direction of the frame set flat curve elbow, the use of this calculation disk, you can directly read the tangent offset, chord offset, chord offset required value. Second, making instructions. Two types of scales are used for the calculation disk: the radius of the circle is 0.107 meters and the inner circle is 0.100 meters. Its advantage is easy to carry, the use of a larger (arc length up to 50 meters). However, poor accuracy can be applied to the hilly plain. 2.1: 200 The outer radius of 0.137 meters, the inner circle of 0.130 meters.