A dial indicator is constructed as following parts:
1. Bezel - it holds the entire dial set up and it is commonly used to establish the zero-reference on the inner face of the dial. The bezel is moveable, once you’ve established the zero-reference, tighten the bezel using the top screw., the bezel can be made of metal or plastic.
2. Bezel Clamp/Locking Screw - It is also called a scale locking screw and locknut. The main function of the bezel clamp is to lock the dial indicator scale after it is calibrated. This acts as the main part to achieve precise measurement.
3. Dust Cap - Dust cap can be found in most of the dial indicators. The main function of a dust cap is to prevent dial indicators from moisture and dust particles.
4. Needle or pointer - Two needles are attached for measurements in a dial indicator, the longer and a shorter needle. To get the reading on an outer scale, a longer pointer is used, they are made of plastic or metal and are light weight to achieve higher sensitivity. The short pointer represents the readings on the inner scale. It spins around the inner scale’s center and serves to point the number markings on the inner scale and offer a reading of how many rotations the long pointer has completed.
5. Scale / Dial - There are two scales inside: the outer scale and the inner scale. The outer scale is the longer pointer points to. Its position spreads over at the edge of the scale circle. The inner scale has a smaller size and commonly positioned somewhere between the center and edge. At the center of the inner scale rotates the short pointer. There are usually 100 division printed on the dial face, each division is equivalent to 0.01mm of measuring rod movement. The dial face can be rotated to any position, this is used to orient the face towards the user as well as set the zero point.
6. Spindle/plunger - Together with the contact point, the plunger moves in and out. When no pressure is gained by the contact point, the plunger will move out completely from the stem. Vice versa, when pressure is applied (measuring mode), the plunger will move in. The movement of the plunger makes the rack to transfer the movement to the pinion, pinion transfers to the gear. Finally, with the help of the pointer attached with the gear, the operators are able to enjoy the measurement reading.
7. Contact point - The contact point is located at the lower part of the dial indicator. This is the dial indicator part where the surface of the object being measured and the dial indicator meets.
8. Tolerance Marker - In order to determine if the measured value meets the specified tolerance range, the spindle is used on the dial to distinguish different areas of the tolerance range.
9. Stem - It plays the role of fixing and supporting the measuring rod due to the slight movement of the measuring head, ensuring the stability and accuracy of the measurement process.
