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Outside Micrometer

 An outside micrometer, also known as an external micrometer, is a precision measuring tool used to measure the diameter or thickness of an object with great accuracy. It is widely used in various industries, including manufacturing, engineering, and machining, where precise measurements are crucial.


The outside micrometer consists of a C-shaped frame with a stationary anvil (the flat end) and a movable spindle (the cylindrical end). The spindle is attached to a thimble and a barrel with a calibrated scale. When the thimble is rotated, the spindle moves inward or outward, allowing the user to measure the dimension of an object placed between the anvil and the spindle.


Here's a breakdown of the key components of an outside micrometer:


Frame: The frame provides stability and support to the anvil and spindle. It is usually made of steel or other rigid materials to ensure accurate measurements.


Anvil: The anvil is the stationary end of the micrometer that comes into contact with the object being measured. It is typically flat and has a hardened surface to prevent wear and maintain accuracy.


Spindle: The spindle is the movable end of the micrometer. It moves towards or away from the anvil when the thimble is rotated. The spindle also has a hardened measuring face that makes contact with the object being measured.


Thimble: The thimble is connected to the spindle and has markings or graduations around its circumference. It is used to rotate the spindle and control its movement. The thimble is typically divided into 25 or 50 equal parts, allowing for precise measurements.


Barrel: The barrel is the cylindrical body that houses the thimble. It contains a linear scale that corresponds to the markings on the thimble. The barrel is fixed to the frame and remains stationary during measurement.


To measure an object using an outside micrometer, you follow these steps:


Clean the measuring faces of the anvil and spindle to ensure accurate readings.


Place the object between the anvil and the spindle. Align it carefully to ensure proper contact.


Rotate the thimble in a clockwise direction to move the spindle towards the object until it makes a light contact.


Apply gentle pressure on the thimble to ensure firm contact between the measuring faces and the object.


Read the value on the linear scale of the barrel that aligns with the zero mark on the thimble. This value represents the measured dimension of the object.


To obtain the final measurement, add the value on the thimble scale to the value on the barrel scale.


Outside micrometers are available in a range of sizes and precision levels to accommodate different measurement requirements. They can measure dimensions ranging from a few millimeters to several inches or more. Some micrometers also come with additional features like ratchet stops to apply a consistent measuring force and digital displays for easier and more precise readings.


In summary, an outside micrometer is a versatile and precise measuring instrument used to determine the diameter or thickness of objects. Its robust construction and accurate measurement capabilities make it an essential tool in industries where precision is crucial.

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