Reading a Metric Micrometer
Reading a metric micrometer is fairly straightforward, similar to a standard micrometer. There are markings on the sleeve and thimble. You will notice the sleeve of a metric micrometer has markings on the top and the bottom. The whole number increments are on one side of the sleeve and the half millimeter increments are on the other.
Depending on the manufacturer, these .50 mm or half millimeter increments may be on the top or the bottom. The thimble of the micrometer is separated into increments of .01 millimeters. Note that there are 50 divisions of .01mm on the thimble of a metric micrometer. Let's have a look at this example.
The micrometer on top is set to 6.50mm. There are 6 whole millimeters on the top and a half a millimeter on the bottom. The thimble is set to 0. When the three are added together the reading is 6.50mm. It’s important to remember that there are increments on both sides, and a complete turn of the thimble will result in .50mm or a half of a millimeter.
The micrometer on the bottom is set to 6.55mm. First add the whole number of 6 millimeters. Then add in the .50 millimeter on the other side of the sleeve. Finally add in the .05 millimeters on the thimble for a total of 6.55 millimeters.
Metric vs. Standard Micrometers
There are differences between metric and standard imperial micrometers. There are markings on the sleeve and also on the thimble of both. The sleeve of a metric micrometer has markings on the top and the bottom. The whole number increments are on one side of the sleeve, and the half-millimeter increments are on the other. There are 50 divisions of .01mm on the thimble of a metric micrometer. The thimble of a standard micrometer has 25 divisions of 0.001 inch. The tool to use all depends on the vehicle and specifications.