如图1所示的工件,要在工件的直径b上划出直径为a的圆弧是困难的。我们参考了绘图用的小圆规和游标卡尺的结构,制成了一种使用方便的特殊圆规,如图2所示。1是定心针。2是套筒,可在定心针上转动。3是摇臂。7是挡块,用螺钉8固定在摇臂3上,它的作用是防止游标4脱离摇臂3。使用前要求笔尖和定心针尖相接触,游标的刻线和摇臂的零线对准。 As shown in Figure 1, the workpiece, the diameter of the workpiece b to draw a circular arc of a diameter is difficult. We refer to the drawing of the compasses and vernier caliper structure, made of a special easy to use compasses, as shown in Figure 2. 1 is the centering needle. 2 is a sleeve that can rotate on the centering pin. 3 is the rocker. 7 is a stopper, with a screw 8 is fixed to the rocker arm 3, its role is to prevent the cursor 4 from the rocker arm 3. Before use requires nib and centering tip contact, cursor calibration and rocker zero line alignment.