HOW TO USE A METRIC MICROMETER The （如何使用度量测微计）.pdfVIP

HOW TO USE A METRIC MICROMETER The metric micrometer looks very similar to a standard inch micrometer until you look at the graduations on the sleeve and the barrel (Figure 1). Figure 1 0-25 millimeter micrometer There are two separate rows of lines on the sleeve of the metric micrometer (Figure 2). Figure 2 When reading a metric micrometer you have to remember to add the half- millimeter graduations of the upper row to the reading. The lower row represents whole millimeter graduations. The upper row represents one-half millimeter. Each complete turn of the thimble moves the spindle ½ millimeter (0.5 mm). The circumference of the thimble is separated into 50 equal divisions (Figure 2) or .01 mm. Reading the Metric Micrometer To read the metric micrometer, first read the number of whole millimeters on the bottom row of the sleeve of the micrometer (Figure 3). These are the whole millimeters. If there is an additional line uncovered on the top row, this is equal to one-half a millimeter (Figure 3). So 0.5 mm would need to be added to the measurement. Then add the thimble reading to whole and half millimeter sleeve readings. Refer to figures 3, 4, and 5 and try to read the measurements before looking at the answer in the figure explanation. Figure 3 Metric micrometer reading equals 23.15 millimeters. 23 whole divisions are uncovered = 23 millimeters. No 0.5 mm millimeters divisions are uncovered = 0.0 millimeters 15 0.01 millimeter divisions line up on the thimble = 0.15 millimeters. Figure 4a Metric micrometer reading equals 18.60 millimeters. 18 whole divisions are uncovered = 18 millimeters. 1 .5 millimeters division is uncovered = 0.5 millimeters 10 0.01 millimter divisions line up on the thimble = 0.10 millimeters Figure 4b Metric micrometer reading equals 15.63 millimeters. 15 whole divisions are uncovered = 15 millimeters. 1 0.50 millimeters division is