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Summary: A micrometer is a precision measuring instrument, and reading one involves looking at both the barrel and the dial. Learn about the subdivisions and incremental measurements of micrometers with help from an auto mechanic in this free video on car repairs and mechanics.
J.B. Hebert is a machinist, metal fabricator, and auto mechanic who has been fixing and modifying all things mechanical for over 20 years. Hebert's small shop in western Massachusetts...read more
"How to read inside a micrometer. A micrometer is a precision measuring instrument. It's designed primarily for measuring outside dimensions on various materials. It's especially good at measuring round material. It can be used for measuring axle shafts, bearings, anything of that nature. It's quite easy to read. On the barrel of the micrometer, there are markings. Each mark represents one hundredth of an inch and they are further subdivided into fifty thousandths and twenty five thousandths markings, so with the micrometer closed on the object that you are looking to measure, you first read the barrel of the micrometer, and in this case you can see that there's four hundred thousandths plus fifty. And then on the dial part of the micrometer, there are markings broken out into twenty five thousandths. And so you simply add the number here to the highest number that you can see. So in this case it would be four fifty, we can actually see seventy five, and then eleven. So this particular item would be four seventy five plus eleven which would be four eighty six."
eHow Article: How to Read Inside a Micrometer