在测量和型形检验角尺的垂直度偏差时,是把它们的工作角与标准检验角尺复现的直角进行比较。这种测量方法有一定缺点:第一,测量准确度要受标准角尺准确度的限制;第二,如果说形角尺的外工作角与标准角尺比较通常是够客观的(例如,采用刚性支架和测量头时),那么内工作角的比较在很大程度上是主观的,因为 The deviation of the squareness of the test and profile test corners is compared with the angle at which their standard work angles are reproduced. First, the measurement accuracy is limited by the accuracy of the standard square; second, if the external angle of the square is more objective than the standard square (for example, using rigid supports and Measuring head), then the comparison of the working angle is largely subjective, because