在机械加工或机修中常会遇到较大直径的轴或圆盘类零件的外径测量问题。如缺乏合适的万能量具进行直接测量时，可采用小规格的游标卡尺进行简接测量，其方法如图所示。　　R2=(b/2)2＋ (R－ h)2　　把算法展开化简，并用 2R=D代入式中即可得：　　b=2 h(D－ h) (1)　　D=(b2/4h In machining or mechanics often encounter large diameter shaft or disk type parts outside diameter measurement problems. Such as the lack of a suitable universal measuring instrument for direct measurement, you can use a small gauge vernier caliper for simple measurements, the method shown. R2 = (b / 2) 2+ (R-h) 2 Expand the algorithm and simplify it by substituting 2R = D into the formula: b = 2 h D - h D = b2 / 4h