How to Read Dial Indicator

In the previous article, we have explained how to use a dial indicator. Now, we are going to be more detailed on how to read the dial indicator. Reading a dial indicator is not like reading a simple ruler, this one is more complicated but not rocket science as well.

What we have to recognize is the resolution. Most dial indicators come with 0.001″ resolution. However, it’s not rare to find them come with 0.0005″ resolution which should be the best dial indicator; the smaller the number means the higher the resolution and accuracy. In this article, we are going to cover how to read these two resolution dial indicators.

Keep in mind that the dial indicator and test indicator use the same reading display though they are different. Therefore, if you are learning how to read a dial indicator, equally you are learning to read a test indicator as well.

While there are several dial indicator types available, however, the way to read the scale basically the same. But we would explain them separately. Without further ado, let’s get to the point.

How to Read A 0.001 Dial Indicator

Let’s come to an example of reading a dial indicator. We assume that you have observed a dial indicator position. Then the state of the two dials (inner and outer dial) is described as this “the dial indicator completed 4 revolutions and the outer dial is on the 5 and a half on the markers”. What is the reading value then? Let’s discuss one by one.

  1. Observation on the inner dial: On the inner dial it is said that the pointer moved 5 and a half. Let’s say our graduation of the dial indicator is 0.001″. It means our measured value on the inner dial is 5.5 x 0.001″ =  0.055″.
  2. Observation on the outer dial: From the paragraph on how to use DI, we learned that the outer dial counts the number of rotations. From the task it is said that our dial indicator completed 4 revolutions. And our outer dial has markers of 0.1 – 1.0″. It means each complete rotations travel 0.1″. So, 4 revolutions travel 4 x 0.1 = 0.4″.

Therefore, in a total  =  0.4″ (outer dial) + 0.055″ (inner dial)=  0.455″.   So, that means wee have tolerance of ±0.455″. In this way, we can determine any measurement in the range of 0-1″.

How to Read A 0.0005 Dial Indicator

The 0.0005 dial indicator means it has a graduation of 0.0005″. In easy words, we can say the smallest division on the inner dial of this dial indicator is 0.0005″.

Let’s say we are using a dial indicator which is continuous. It has 10 continuous divisions on the inner dial. We have 10 smaller divisions between the main division. And then we have 2 smallest division in between the smaller division. So, if our main division is 0.01″, our smaller division is 0.001″. Therefore the smallest division would be 0.0005″.

Consecutive 2 smallest division one smaller division. On the scale, 0.0005″ x 2 = 0.001″. Consecutive 10 smaller division we get one main division. On the scale, 0.001″x10= 0.01″. We use this 0.0005 dial indicator for more accurate results.

Let’s say our pointer completed no rotation. The pointer crosses the 7th markers and passed 8 smaller divisions. It just came near to the next smallest division. How to find the exact result? Let’s do it one by one.

  1. Reading on the outer dial: It is said no complete rotation that means the outer dial reading= 0 x 0.1″= 0.00″.
  2. Reading on the inner dial: It is said the pointer crossed the 7th So, the main division result= 7 x 0.01″= 0.07″. After that our pointer passed consecutive 8 smaller divisions. Therefore, our smaller division= 8 x 0.001″= 0.008″. Later it is said the pointer is near the next smallest division. Therefore, 1 x 0.0005″ = 0.0005″.
  3. Calculation: Now, let’s add them to get our final result. The total traveled distance = outer dial reading + main division value + smaller division value + smallest division value = 0.00″ + 0.07″ + 0.008″ + 0.0005″ = 0.0785″.

In this way, we take consecutive five readings and find an average value. Making a table will beautify our readings and calculations.

Summary

So many points to remember right? Let’s have a glance at the summery. To use a dial indicator; we must follow these steps. Rigid mounting >> Identification of the measurement marks >> Measurement on inner and outer dial >> Calculation >> Preservation.

To read a dial indicator we must observe both the outer and inner dial according to their graduations. Besides, to read a 0.0005″ dial indicator we must focus on the various measuring divisions.

After all, it is important to make the measurement more formal. Let’s say you have started the calculation using the dial indicator. You must follow some formal manner. So that later you can quickly get an idea about your last measured value.

To make a formal calculation, we must follow these points:

  1. Rename your note as your company name.
  2. Note down your object name.
  3. Note down the dial indicator and its measuring range and graduations.
  4. We must include the experiment date.
  5. We must note the specific extension and contact point we will use for the operation.
  6. The tabulation must contain consecutive 5 values and their average.
  7. The calculation and the table must be well organized, neat, and clean.
  8. After the observation, we must preserve it for the next.

As we know, to become a great engineer, we must be formal and experienced. We must follow the definition of the engineering procedure. So that we can get an absolute result whatever we go to measure.