Micrometer Body Parts Explained

It’s important to learn the micrometer body parts. It gives you a clear idea of how to use a micrometer, how to take the reading, and how it works. On this page, you’ll learn several micrometer body parts that you’ll find on a mechanical (vernier) micrometer.

A typical mechanical micrometer consists of the following body parts:

  • Frame: The frame is the U-shaped part of a micrometer. It also represents the range of measurement. The larger the frame, the longer the range. Whereas, the smaller the frame, the shorter the range. It also provides support to the anvil and the spindle to secure the object. In addition, it’s commonly coated with plastic material to prevent the user’s body heat moves to the micrometer.

    The Parts of Micrometer
    The Parts of Micrometer
  • Anvil: Anvil is the stationary part of a micrometer where the object to be measured is held. It connects to the frame. There are various types of micrometers classified based on the anvil. There’s a particular micrometer in which the anvil is changeable. It means that you can replace it with another anvil type.
  • Spindle: Spindle functions like the anvil; holding the object to be measured, however, it’s the moveable one. By turning around the thimble, the anvil will rotate as well and axially moves forward or backward to both tighten and untighten the object as the users need. A spindle is actually a long tube metal in which half of its body is threaded. Therefore, it also directly connects to the screw.
  • Lock: You need to use this part to prevent the spindle from moving while taking the reading because any movement can cause inaccuracy. By turning it, you hold the object tightened. On the image above, it’s a nut lock type. You may notice another lock with a different look like a ring which is rotated to use it, but it functions the same.
  • Sleeve: The sleeve is a barrel where the primary scale of the micrometer takes place and the thimble rotates around it. It could be in millimeter or inch scale depends on the type you have. It’s stationary and in some cases, the vernier scale is etched on there. You’ll find an index line is located on there as well.
  • Thimble: The thimble is a barrel that looks like the sleeve as well, however, it acts as the movable one. It is bigger than the sleeve in terms of its diameter and therefore, rotates around the outer side of the sleeve. Also, it’s the area of the secondary scale etched. It functions to magnify the resolution of the main scale, one division on the primary scale divided into more divisions again.
  • Ratchet: Ratchet is a rotatable cylindrical part situated at the very end of the micrometer. It functions in such a way so that the object is held with appropriate pressure. Your micrometer can be broken if the pressure is too tight, whereas the reading is not accurate if the pressure is too weak. It releases a click sound if the object is pressed with appropriate pressure.
  • Measuring Faces. Measuring faces are the surface that touches the objects to be measured. They take place on the edge of the anvil and spindle. If the micrometer is set to be zero, they will meet and touches together. These measuring faces should be made of strong material. In the past, the manufacturers used hardened steel to empower the measuring faces. Today, the vast majority of the company have been using carbide material to tip the measuring faces. And carbide has been recognized as the better material to be.
  • Screw: The screw determines how a micrometer works. It is the critical part of a micrometer. The screw is positioned inside of the thimble barrel so you need to unassemble the micrometer to uncover the screw’s real shape. So this screw is actually a threaded spindle because it connects each other.

    spindle screw
    The Spindle and Threaded Spindle (Screw)
  • Scales: We take the reading on the scales. A micrometer has two main scales: the main scale which is located on the sleeve barrel and the second scale which is located on the thimble barrel. They can be in the metric (mm) or the imperial system (inch). Therefore, because they are not both using electronic display, a mechanical micrometer has only one type of unit measurement, metric or imperial. There are some micrometers with an additional vernier scale on the upper side of the sleeve scale to provide greater resolution.

Those are the parts of a mechanical vernier micrometer. We hope you like it. If you may be in a search of a new micrometer for your project, you may find our micrometer reviews helpful to start the search.