GB/T1216-200412A部详图1一测砧:2一测微螺杆:3棘轮:4一尺架:5隔热装置:6一测量面:7一模拟显示:8一测微螺杆锁紧装置:9固定套管:10一基准线:11一微分简:12一数值显示.图1外径千分尺4.2基本参数外径千分尺的量程为25mm,测微螺杆螺距为0.5mm和1mm,测量范围见表1。表1单位为毫米测量范围025,2550,5075,75100,100125,125150150175,175200,200225,225250,250275,275300300325,325350,350375,375400,400425,425450450475,475500,500600,600700,700800,80090090010005要求5.1外观外径千分尺不应有影响使用性能的锈蚀、碰伤、划痕、裂纹等缺陷。2