Depth Micrometer Vs. Depth Caliper

There are several reasons why the depth micrometer is superior to the depth caliper. But, vice versa, there are also several points that depth caliper is better than depth micrometer.

On another page, we discuss the difference between a micrometer and a caliper. But, it seems not a complete comparison, not specifically comparing the depth models. On this page, we will talk about an in-depth comparison between depth caliper and depth micrometer.

So, if you are going to buy either of these tools, you’ll know which one is the right tool to buy for you. We analyze the differences through the seven factors: resolution, speed, accuracy, applications, cost, standard, and calibration.

1. Resolution

Depth Micrometer:

Resolution is also called as graduation which is the smallest reading a caliper or micrometer can measure. The depth micrometer measures up to a depth resolution of about 50 millionth ( .00005″ = 0.00127 mm) and is therefore useful for parts that have features like internal notches.

Depth Caliper:

Whereas the resolution of a depth caliper is only about .0005″ (0.01 mm).

Therefore, the resolution of a depth micrometer is ten times better than a depth caliper which allows for the depth micrometer to be utilized in the measurement of important profile features that are otherwise not possible to be read with a depth caliper having lesser resolution. But the higher resolution of a depth caliper comes at the cost of a lower measuring range and difficult measuring mechanism.

2. Speed / Ease of Measurement

Depth Micrometer:

The operation of a depth micrometer involves a thimble that needs to be revolved to be adjusted to the depth being measured which is time taking as the thimble needs to be turned clockwise or counterclockwise for it to move as needed.

Depth Caliper:

Whereas, for a depth caliper, the operation is straightforward as no thimble needs to be adjusted and the user can easily adjust to the required depth using the stopper provided. In other words, you just need to slide. This makes the ease of use of the depth caliper far more than a depth micrometer.

But ease of use should only be opted for when the dimensions being measured are not as critical and can do with a lower level of instrument accuracy like that of a depth caliper. If the dimensions being measured are important and need a high level of accuracy, then a depth micrometer should be preferred for use.

3. Accuracy

Depth Micrometer:

It must be known that a depth micrometer offers greater accuracy as compared to a depth caliper. The depth micrometer, although the resolution is only .001″, it can reach an accuracy of ±.00015″ (Mitutoyo 129-127). Remember that accuracy and resolution are two different things. If greater accuracy is preferred rather than the ease of use or speed of measurement, then a depth micrometer is used.

Depth Caliper:

Depth calipers are used for low-accuracy measurements. An example of a depth micrometer such as Mitutoyo 571-263-10 provides only .0015″ accuracy.

4. Applications

Depth Micrometer:

Depth calipers are used for applications like the measurement of the depth of any surface relative to a reference surface. Their use is extensive due to the ease of taking measurements with good accuracy. They can either be utilized for measurement of a depth of a hole, recesses, and distances from a plane surface or a level difference between two surfaces.

It is also interesting to acknowledge that the depth caliper can be really useful for application in situations where dimensions require a large measuring range.

Depth Caliper:

On the other hand, a depth micrometer is typically utilized for measuring the depth of small holes and bores of any object that requires a high degree of accuracy. But, its measurement range is usually limited. This limitation makes micrometer depth gauge requires an extension rod for larger readings.

But summarizing the application of both, it can be stated that since depth micrometer is more accurate it finds use in measurement of dimensions that require a higher level of accuracy and precision and time is not a critical factor, whereas if ease of use is required, the demand of accuracy is not as important, and time is critical then depth caliper is the preferred instrument.

5. Cost

Depth Micrometer:

It is suggested to use digital depth micrometer for fast and accurate readings if time is an issue instead of analog depth micrometer. However, you may have to know that digital depth micrometers are costlier than analog ones.

Depth Caliper:

Moreover, the cost of a depth caliper is not as high as a depth micrometer which makes access to depth caliper even easy and more convenient. This is because depth calipers have a simple construction and mechanisms as compared to depth micrometers. Therefore, professionals are required to consider their needs carefully before making a decision.

6. Standard for Calibration

Both depth micrometer and depth caliper can use a gauge block for calibration. You actually need a ring standard, but gauge block may save you money because gauge block can calibrate other tools such as outside micrometer and outside caliper.

Length Error Test for Depth Micrometer

Final Verdict

The final decision upon use/ purchase of any of these two equipments depends on the following as per our above discussion:

  • If accuracy is required choose a depth micrometer
  • If time-saving is needed choose a depth caliper
  • If ease of operations is desired, both while using and calibrating, use depth caliper
  • Use depth micrometer that is digital if you can afford for better and quick results
  • Establish a practice prior to a project so that it is easy to decide on the use of a particular equipment.

Engineering practices are always shaped on the basis of on ground experience and results. If deviations in results are observed with the use of a specific instrument it is suggested to either check the calibration of such an equipment or replace the equipment with an equipment that is even more accurate in results it gives.