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

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 (0.00127mm/ 0.00005”) and is therefore useful for parts have features like internal notches. Whereas the resolution of a depth caliper is around 0.01mm/ 0.0005”.

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 which are otherwise not possible to be read with depth caliper having lesser resolution. But higher resolution of a depth caliper comes at the cost of lower measuring range and difficult measuring mechanism.

2. Speed / Ease of Measurement

The operation of 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 for it to move as per the requirement.

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

3. Accuracy

It must be known that a depth micrometer offers greater accuracy as compared to a depth caliper. The reason is because the least count of a micrometer is 0.01mm and that of a Vernier caliper is 0.1mm. This is why if greater accuracy is preferred rather than the ease of use or speed of measurement, then a depth micrometer is used.

Depth calipers are used for low tolerance measurements just like a micrometer depth gauge. However, if the tolerance limits are way minimal then a micrometer depth gauge is recommended as compared to a depth caliper. Therefore, the allowable tolerance limits of a calculation must be known.

4. Applications

Depth calipers are used for applications like measurement of 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.

On the other hand, a depth micrometer is typically utilized for measuring the depth of small holes and bores of any object. However, these are limited to a measurement of dimensions up to 25mm. This is why it finds use in various manufacturing industries in the manufacture of precise parts and equipment.

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. On the other hand, micrometer depth gauge which is limited to 25mm range 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 which require a higher level of accuracy and precision and time is not a critical factor, whereas if ease of use is required, demand of accuracy is not as important, and time is critical then depth caliper is the preferred instrument.

5. Cost

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

Moreover, the cost of a depth caliper is not as high as a depth micrometer which makes access to depth caliper even easy and convenient. This is because depth calipers have a simple construction and mechanisms as compared to depth micrometer. Therefore, professionals are required to access their need carefully before making a decision over purchase of an instrument so that their purchase is practical.

6. Standard

Depth Micrometer is as per international standard and is preferred in standard practices whereas depth caliper’s rod is not as supported for its use as per any standard and is only a function available for comparison. This is because depth micrometer is much more accurate and made for this very purpose whereas depth caliper is an additional function of Vernier caliper.

This is why it is a norm in industrial practices to set a method of execution of quality control works prior to execution of a product. This helps to establish the right use of tool for the right dimension and helps to avoid unnecessary errors due to human judgement and personal preferences.

7. Calibration

Due to a comparatively complex mechanism it is seen that the calibration for depth micrometer is a bit trickier and mostly requires professional calibration labs for most accurate and acceptable calibration. Whereas, depth calipers can be calibrated easily and in-house calibration can also be performed more accurately.

Final Verdict

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

  • If accuracy is required choose depth micrometer
  • If time saving is needed choose 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.