Metrology in the Automotive Field: Complete Guide to Measurements and Precision Instruments

13. Caliper: what is it and what is it for?

The caliper is one of the most widely used measuring instruments in automotive mechanics. Its main advantage is that it can measure different dimensional features with a single instrument.

With a universal caliper, the mechanic can check outside diameters, certain inside diameters, thicknesses, depths and steps, depending on the model’s construction.

This instrument is widely used during the disassembly, inspection and assembly of automotive components.

13.1. Examples of use

Imagine the mechanic is assessing a shaft removed from a transmission. Before deciding whether the component can be reused, they need to know some of its dimensions.

The caliper can be used for an initial check of that shaft’s outside diameter.

In another situation, the professional can use the caliper’s depth rod to check the depth of a cavity.

It is also possible to check the thickness of certain parts, provided the instrument has characteristics suited to the measurement.

14. Getting to know the parts of the caliper

To use the caliper correctly, the student needs to know its main parts and understand the function of each.

14.1. Main scale

The main scale shows the instrument’s main graduations. On a metric caliper, these graduations are normally in millimeters.

This is the scale where the operator reads the whole-number part of the measurement.

14.2. Sliding jaw

The slider moves along the main scale. Moving it brings the measuring jaws closer together or further apart.

The slider’s movement follows the dimension of the part being checked.

14.3. Nonius or vernier

The vernier is an auxiliary scale on the sliding jaw.

Its function is to allow fractions of the smallest division of the main scale to be read.

The reading is obtained by seeing which vernier division lines up with a division on the main scale.

14.4. Outside measuring jaws

Used to measure outside dimensions, such as shaft diameters, thicknesses and widths.

The contact surfaces must be clean and correctly seated on the part.

14.5. Inside measuring jaws

Used to check certain inside dimensions, such as the opening of a bore.

The jaws must be positioned correctly to avoid readings smaller or larger than the intended dimension.

14.6. Depth rod

The rod moves with the slider and allows depths to be measured.

During measurement, the instrument’s base must remain correctly positioned on the reference surface.

15. Types of measurement with a caliper

The universal caliper can perform different types of measurement. It is important to know each application in order to select the right contact surfaces.

15.1. Outside measurement

For outside measurement, the part is placed between the instrument’s larger jaws.

The operator closes the jaws until there is proper contact with the surfaces.

Excessive force must not be applied, as it can distort the part or cause a positioning error.

15.2. Inside measurement

For inside measurement, the appropriate jaws are inserted into the part’s opening.

The slider is moved until it contacts the inside surfaces.

The instrument must stay correctly aligned with the dimension being checked.

15.3. Depth measurement

The depth rod is inserted into the cavity.

The base of the instrument must remain resting on the reference surface, without tilting.

15.4. Step measurement

Some calipers have specific surfaces for checking the height difference between two planes.

16. How does the vernier work?

To understand how to read an analog caliper, you need to understand how the vernier works.

The main scale has length graduations. The vernier has divisions with spacing slightly different from that of the main scale.

This difference means that, depending on the slider’s position, a certain vernier line lines up with a line on the main scale.

The operator uses this alignment to determine the fractional part of the measurement.

16.1. 0.1 mm caliper

In a traditional metric design, the vernier has ten divisions and allows readings in 0.1 mm increments.

16.2. 0.05 mm caliper

In a traditional twenty-division design, the resolution is 0.05 mm.

16.3. 0.02 mm caliper

In a traditional fifty-division design, the resolution is 0.02 mm.

17. Reading a 0.1 mm caliper

The first step is to look at the main scale.

Identify the last whole millimeter passed by the vernier zero.

Then find the vernier line that lines up with a line on the main scale.

Multiply the position of that line by the resolution.

Finally, add the values.

17.1. Solved example

Consider:

• Main scale: 12 mm.
• Resolution: 0.1 mm.
• Alignment: fourth division.

The fractional part will be:

The complete reading will be:

17.2. Second example

Main scale: 18 mm.

Alignment: sixth division.

Resolution: 0.1 mm.

18. Reading a 0.05 mm caliper

The procedure is similar, but each vernier division equals 0.05 mm.

18.1. Solved example

Main scale: 24 mm.

Alignment: seventh division.

Resolution: 0.05 mm.

First, calculate the fractional part:

Then add:

18.2. Example with 31.55 mm

Main scale: 31 mm.

Alignment: eleventh division.

18.3. Illustration of an actual reading

The following figure shows an enlarged diagram of a 0.05 mm vernier.

The vernier zero is between 24 and 25 mm on the main scale.

The alignment corresponds to the seventh vernier division.

19. Reading a 0.02 mm caliper

A caliper with 0.02 mm resolution allows readings in increments of two hundredths of a millimeter.

In a traditional design, the vernier has fifty divisions.

19.1. Solved example

Main scale: 70 mm.

Alignment: 38th division.

Resolution: 0.02 mm.

19.2. Second example

Main scale: 42 mm.

Alignment: 17th division.

19.3. Comparing resolutions

Note that the same alignment position produces different values when the instrument’s resolution changes.

That is why identifying the resolution is an essential step.

20. Inch caliper

Some calipers have an inch scale in addition to the metric scale.

The reading can be fractional or decimal, depending on the instrument.

20.1. Decimal caliper

In a traditional design, the main scale may have 0.025 inch divisions, while the vernier allows readings of 0.001 inch.

20.2. Fractional caliper

On certain models, the main scale has 1/16 inch divisions and the vernier allows readings of 1/128 inch.

The operator must identify the specific graduation before calculating the measurement.

21. Common mistakes when using a caliper

21.1. Parallax error

Parallax error occurs when the operator looks at the scale from the wrong angle.

On analog instruments, this can make it hard to identify the aligned lines correctly.

21.2. Excessive pressure

Applying too much force can distort delicate parts or shift the slider.

21.3. Tilting

The instrument must be correctly aligned with the dimension being measured.

A tilted measurement can produce an incorrect result.

21.4. Dirt

Chips, particles and residue between the faces can change the reading.

21.5. Damaged jaws

Drops and impacts can damage the contact surfaces.

21.6. Reference error

Before measuring, check that the instrument behaves correctly at the reference condition.

22. Correct outside measurement procedure

Suppose the mechanic wants to measure the diameter of a shaft.

Step 1 — Preparation

Clean the shaft surface and the caliper faces.

Step 2 — Check

Check the condition of the instrument.

Step 3 — Positioning

Open the outside jaws and place the shaft between the contact surfaces.

Step 4 — Contact

Close the jaws gently, without applying excessive force.

Step 5 — Alignment

Check that the instrument is correctly positioned relative to the diameter.

Step 6 — Reading

Look at the main scale, identify the vernier alignment and calculate the result.

Step 7 — Recording

Record the measurement with the correct unit.

Step 8 — Comparison

Compare the result with the manufacturer’s specification.

23. Practical applications in the automotive workshop

23.1. Measuring thickness

The caliper can be used to measure the thickness of certain parts, provided the geometry allows proper contact.

23.2. Measuring shafts

It can be used for an initial dimensional check of shafts.

When the tolerance requires tighter control, a micrometer may be needed.

23.3. Measuring depth

The depth rod allows cavities and recesses to be checked.

23.4. Checking openings

The inside jaws allow certain openings and bores to be measured.

Whether the instrument is suitable depends on the geometry and tolerance.

24. Solved caliper reading exercises

Exercise 1

A 0.1 mm caliper shows a main scale reading of 15 mm and alignment at the third division.

Calculation:

Exercise 2

A 0.05 mm caliper shows a main scale reading of 28 mm and alignment at the ninth division.

Exercise 3

A 0.02 mm caliper shows a main scale reading of 56 mm and alignment at the 23rd division.

Exercise 4

A 0.05 mm caliper shows a main scale reading of 32 mm and alignment at the 14th division.

Exercise 5

A 0.02 mm caliper shows a main scale reading of 75 mm and alignment at the 31st division.

25. Exercise: interpreting an automotive part

Imagine the mechanic is checking the outside diameter of a shaft.

The caliper shows:

• Main scale: 25 mm.
• Resolution: 0.05 mm.
• Alignment: eighth division.

First, calculate the fractional part:

Then add:

The measured diameter is 25.40 mm.

However, this value alone does not tell you whether the shaft passes.

To determine the component’s condition, you must consult the applicable dimensional limits.

26. Caliper care and maintenance

The caliper is a measuring instrument and must not be used as a general-purpose tool.

Never use the caliper to clamp parts, pry or scribe surfaces.

Avoid drops and impacts.

Clean the surfaces before and after measuring.

Do not force the slider when there is abnormal resistance to movement.

Store the instrument in its case and follow the manufacturer’s care recommendations.

27. Review of Part 2

In this stage, you learned how the universal caliper works, its main parts and its applications in automotive mechanics.

You also learned to calculate readings on calipers with resolutions of 0.1 mm, 0.05 mm and 0.02 mm.

You also studied the main measurement errors, care and maintenance, and practical examples of use in the workshop.

In Part 3: we will study the micrometer in depth, including how the micrometer spindle works, the sleeve and thimble scales, 0.01 mm and 0.001 mm readings, solved examples and embedded illustrations.

28. Micrometer: high-precision measurement

The micrometer is a dimensional measuring instrument widely used to inspect automotive components that require tighter dimensional control.

It works by moving a threaded spindle of known pitch. When the thimble is turned, the spindle advances or retracts a distance proportional to the rotation.

In automotive mechanics, the outside micrometer is often used to check the diameters of shafts, main journals, crankpins, pistons and other outside surfaces, provided the instrument suits the part’s geometry.

28.1. Main micrometer components

The traditional outside micrometer has a frame, fixed anvil, moving spindle, sleeve, thimble, controlled-force device and, on many models, a spindle lock.

28.2. Function of each component

Frame: supports the assembly and keeps the measuring elements structurally aligned.

Anvil: provides the fixed contact surface.

Spindle: has the moving surface that approaches or moves away from the anvil.

Sleeve: carries the longitudinal reference scale.

Thimble: is turned by the operator and carries the graduations used for reading.

Ratchet or force device: helps apply a more consistent measuring force.

29. How the micrometer works

In many traditional metric micrometers, the spindle has a 0.5 mm pitch. This means one full turn of the thimble moves the spindle 0.5 mm.

When the thimble has 50 divisions, each division represents:

Therefore, on this model, the reading resolution is 0.01 mm.

Other models and designs exist. Always check the manufacturer’s information before interpreting the scale.

30. Reading a 0.01 mm micrometer

The traditional reading is done in two main steps.

First, read the last whole millimeter visible on the sleeve. Also check whether the additional 0.5 mm mark has been passed.

Then identify the thimble division that lines up with the sleeve’s reference line.

30.1. Solved example

Consider a micrometer with:

• Whole sleeve reading: 12 mm.
• Half-millimeter mark visible: 0.5 mm.
• Thimble aligned at division 23.
• Thimble resolution: 0.01 mm.

The thimble reading will be:

The total reading will be:

30.2. Second example

Sleeve: 18 mm.

0.5 mm mark: not passed.

Thimble: division 36.

30.3. Third example

Sleeve: 7 mm.

Additional mark: 0.5 mm.

Thimble: division 8.

31. 0.001 mm micrometer

Some micrometers have a resolution of 0.001 mm, equivalent to one micrometer as a unit of length.

On traditional analog models, an auxiliary scale allows additional fractions of the thimble division to be identified.

The exact reading procedure depends on the instrument’s construction.

31.1. Example of building up the reading

Consider an instrument whose reading is made up of:

• Sleeve: 8.5 mm.
• Thimble: 0.27 mm.
• Auxiliary scale: 0.004 mm.

This example shows how values from different scales can be added. The position and interpretation of the auxiliary scale must follow the model used.

32. How to measure correctly with a micrometer

32.1. Preparation

Clean the part and the contact surfaces. Check for chips, excess oil, burrs or dirt.

32.2. Checking the instrument

Confirm that the micrometer is in good condition and that its measuring range matches the part’s dimension.

32.3. Positioning

Place the part between the anvil and the spindle, keeping proper alignment.

32.4. Applying force

Use the controlled-force device as directed by the manufacturer. Avoid clamping the part too tightly.

32.5. Reading and recording

Read the scales carefully and record the result with the corresponding unit.

32.6. Repetition

When necessary, repeat the measurement at different positions to investigate dimensional variations.

33. Micrometer applications on the engine

The outside micrometer is important for checking engine components with tight tolerances.

33.1. Measuring pistons

Piston diameter must be measured at the area and in the direction specified by the manufacturer.

This is necessary because pistons may not be perfectly cylindrical and may have dimensional variations designed for their operation.

33.2. Measuring crankshafts

Main journals and crankpins can be measured at different positions to investigate wear, out-of-roundness and taper.

33.3. Measuring shafts

The micrometer allows outside diameters to be checked with more control than a preliminary caliper measurement.

Approval of the component depends on the applicable dimensional limits.

34. Dial indicator

The dial indicator is an instrument used to detect small variations in displacement relative to a reference.

Unlike an instrument intended for directly measuring a diameter, it is often used to compare positions, displacements and geometric deviations.

In automotive mechanics, it can be used to assess warping, runout, end play and other displacements.

34.1. Main components

The dial indicator normally has a dial face, pointer, graduated scale, moving plunger, contact point and mounting device.

35. How the dial indicator works

When the contact point moves, the internal mechanism transmits that movement to the pointer.

The displacement shown depends on the instrument’s graduation. On common models, each division may represent 0.01 mm.

Other models have different resolutions. That is why the scale must be identified before use.

35.1. Reading example

Consider a dial indicator with 0.01 mm resolution.

If the pointer moves 18 divisions, the indicated displacement will be:

This reading represents the displacement relative to the chosen reference.

35.2. Zeroing

In many applications, the operator positions the contact point, applies the recommended preload and sets the dial to establish a reading reference.

Zero is a comparative reference and does not necessarily mean no dimension or no clearance.

36. Dial indicator applications

36.1. Runout

Runout can be assessed while the part rotates about an axis or reference system.

The difference between the maximum and minimum readings can represent the total indicated runout, depending on the procedure used.

36.2. End play

In certain assemblies, the dial indicator allows the axial movement of a component to be assessed.

The procedure must follow the conditions set by the manufacturer.

36.3. Checking for warping

The instrument can be used in suitable setups to check variations in the position of surfaces.

The result must be interpreted considering the mounting, alignment and job specifications.

37. Dial bore gauge: measuring inside diameters

The dial bore gauge, also known as an inside diameter comparator, is widely used to inspect engine cylinders and other bores.

It normally works as a comparative instrument, set from a known reference dimension.

The operator inserts the instrument into the cylinder and watches the variation indicated relative to the reference.

37.1. Why use a bore gauge?

A cylinder may wear differently along its height and in different directions.

The bore gauge allows inside diameters to be compared at several positions and dimensional variations to be identified.

38. How to use the bore gauge

38.1. Selecting the range

Choose an instrument and accessories suited to the diameter to be measured.

38.2. Setting the reference

Use the appropriate master or reference set to establish the nominal dimension or another known dimension.

38.3. Inserting into the cylinder

Position the bore gauge inside the cylinder, respecting the desired measuring direction.

38.4. Rocking motion

Perform the recommended controlled rocking motion to find the pointer’s reversal point, which corresponds to the instrument’s correct measuring position.

38.5. Interpretation

Compare the indication with the reference. Whether the variation is positive or negative depends on the instrument’s configuration and the setting made.

39. Cylinder out-of-roundness and taper

While the engine runs, the cylinders are subject to friction, temperature and mechanical loads.

Over time, they may wear unevenly.

39.1. Out-of-roundness

Out-of-roundness is a difference between diameters measured in different directions in the same section.

39.2. Taper

Taper, in a simplified wear assessment, can be investigated from the difference between diameters measured at different heights of the cylinder, in the same direction.

40. How to record cylinder measurements

To assess a cylinder properly, the professional can take measurements at different heights and directions, according to the service procedure.

An organized record makes it easier to compare results.

The values in this table are teaching examples only. They do not represent the specifications of a real engine.

The diagnosis must consider the wear limits, the component geometry and the procedure set by the manufacturer.

41. Feeler gauge

The feeler gauge, also known as a blade set or clearance gauge, consists of blades of known thickness.

It is used to check certain clearances between mechanical surfaces.

A traditional application is checking valve clearance on engines whose adjustment procedure uses this tool.

41.1. Basic procedure

Select the blade corresponding to the specified value.

Insert it between the surfaces under the measuring condition indicated by the manufacturer.

Assess the contact and the blade’s resistance to movement according to the service procedure.

Do not force the blade and do not use damaged or bent blades.

42. Radius gauge

The radius gauge is used to compare the profile of a curve with known radius templates.

It can help check certain fillets and component profiles.

The operator selects the matching blade and observes how well it fits the surface.

This procedure is comparative and depends on lighting, positioning and part geometry.

43. Resolution, repeatability and accuracy

In metrology, some terms seem similar but have different meanings.

43.1. Resolution

The smallest variation in the measured quantity that causes a perceptible change in the instrument’s indication, depending on its construction and use.

A caliper with 0.02 mm resolution shows increments of that order.

This does not mean that any measurement made with it will have a maximum error of 0.02 mm.

43.2. Repeatability

Relates to how close the results of repeated measurements are under repeatability conditions.

If the operator measures the same part several times and gets very different values, the measuring conditions must be investigated.

43.3. Accuracy

Accuracy relates to how close a measurement result is to the true value of the quantity, which is normally not known perfectly.

Metrological assessment requires considering errors, uncertainty and measuring conditions.

44. Calibration and adjustment

Calibration establishes a relationship between an instrument’s indications and reference values, considering the associated uncertainties.

It reveals the instrument’s metrological behavior.

Adjustment is an intervention intended to make the instrument give indications suitable for its intended use.

Calibrating and adjusting are not the same operation.

After certain adjustments, a new calibration may be needed to assess the instrument’s behavior.

45. Errors that compromise measurements

45.1. Unsuitable temperature

Parts and instruments can expand or contract with temperature changes.

In critical measurements, the reference temperature and the applicable procedure must be considered.

45.2. Dirty instrument

Particles between contact surfaces can change the indication.

45.3. Incorrect positioning

A tilted or misaligned instrument can produce a different result than expected.

45.4. Unsuitable measuring force

Excessive force can distort components or change the contact condition.

45.5. Damaged instrument

Impacts, wear and corrosion can compromise reliability.

45.6. Incorrect interpretation

A misread scale can lead to an incorrect diagnosis, even when the instrument is in good condition.

46. Dimensional tolerances

In manufacturing, it is not possible to produce all parts with absolutely identical dimensions.

That is why designs set nominal dimensions and permissible variation limits.

Dimensional tolerance is the difference between the maximum and minimum dimensional limits.

46.1. Teaching example

Consider a part with:

• Maximum dimension: 30.02 mm.
• Minimum dimension: 29.98 mm.

The total dimensional tolerance is 0.04 mm.

46.2. Assessing the part

If the part measures 30.01 mm, it is within the dimensional limits of this example.

If it measures 30.05 mm, it is above the maximum limit.

These values are fictitious and serve only to demonstrate the concept.

47. Clearance and interference

When two parts are assembled, their dimensions can produce clearance or interference.

47.1. Clearance fit

In a simplified example, when the inside diameter of a bore is larger than the outside diameter of the shaft, there is a positive diametral difference.

47.2. Interference fit

When the shaft has a larger diameter than the bore, there may be an interference condition.

48. Metrology applied to diagnosis

A measurement only becomes useful information when it is interpreted correctly.

The professional must identify the component, select the appropriate instrument, take the measurement and compare the result with the applicable technical limits.

48.1. Example: engine cylinder

The mechanic checks the cylinder at different heights and directions.

The measurements allow differences in diameter associated with wear to be investigated.

The decision to hone, rebore or replace depends on the part’s condition and the manufacturer’s limits.

48.2. Example: crankshaft

Measuring the diameters of the main journals and crankpins allows dimensional variations to be assessed.

This data helps identify wear and define the repair or replacement procedure.

48.3. Example: brake disc

Disc thickness must be compared with the specified minimum limit.

Runout can also be assessed when the inspection procedure calls for it.

The choice of instrument and measuring points must follow the manufacturer’s guidance.

49. Good metrology practice in the workshop

A reliable measuring routine should include organization, cleanliness and proper recording.

• Correctly identify the part and the quantity to be measured.
• Consult the corresponding technical specification.
• Select an instrument with suitable range and performance.
• Check the instrument’s condition.
• Clean the part and the contact surfaces.
• Control environmental conditions when necessary.
• Take the measurement without excessive force.
• Repeat measurements when appropriate.
• Record the results with their units.
• Compare the results with the applicable limits.

50. Case study: dimensional assessment of a shaft

Consider a shaft whose permissible dimensional range, in this fictitious example, is 39.97 mm to 40.00 mm.

The mechanic takes three measurements:

The first two measurements are within the given dimensional range.

The third is below the minimum limit.

Therefore, the set of results reveals a condition that requires investigation and assessment according to the applicable technical procedure.

It would not be correct to approve the part based only on the first measurement.

51. Final assessment: 10 automotive metrology questions

Answer the following questions to review the concepts studied in this course.

Each question has four options: A, B, C and D. Only one option is correct.

Question 1

What is the main purpose of metrology in automotive maintenance?

A) To replace all diagnostic procedures.

B) To determine quantities through reliable measurements.

C) To eliminate the need to consult technical manuals.

D) To allow any instrument to be used for any job.

Question 2

One inch equals exactly:

A) 2.54 mm.

B) 24.5 mm.

C) 25.4 mm.

D) 254 mm.

Question 3

A caliper with 0.05 mm resolution shows 20 mm on the main scale and alignment at the sixth vernier division. What is the reading?

A) 20.06 mm.

B) 20.30 mm.

C) 20.50 mm.

D) 26.00 mm.

Question 4

A micrometer shows 12 mm on the sleeve, plus 0.5 mm visible, and 0.23 mm on the thimble. What is the reading?

A) 12.23 mm.

B) 12.50 mm.

C) 12.73 mm.

D) 13.23 mm.

Question 5

Which instrument is especially used to compare small variations in displacement, as in runout checks?

A) Graduated rule.

B) Radius gauge.

C) Dial indicator.

D) Ordinary tape measure.

Question 6

In automotive mechanics, the bore gauge is often used to:

A) Directly measure oil temperature.

B) Compare inside diameters of cylinders.

C) Check battery voltage.

D) Apply torque to bolts.

Question 7

At the same cylinder height, 80.02 mm was found in one direction and 80.06 mm in another. What is the difference between the diameters?

A) 0.02 mm.

B) 0.04 mm.

C) 0.06 mm.

D) 0.08 mm.

Question 8

A feeler gauge is normally used to:

A) Check certain clearances between surfaces.

B) Measure fuel pressure.

C) Measure electric current.

D) Determine engine speed.

Question 9

A part has a maximum limit of 30.02 mm and a minimum of 29.98 mm. What is its total dimensional tolerance?

A) 0.02 mm.

B) 0.03 mm.

C) 0.04 mm.

D) 0.08 mm.

Question 10

Which statement about resolution and accuracy is correct?

A) They are terms with exactly the same meaning.

B) Higher resolution guarantees no measurement error.

C) Resolution alone tells you whether a part passes.

D) Resolution must not be confused with accuracy.

52. Answer key with comments

Question 1 — Answer B

Metrology allows quantities to be determined through measurement. In automotive maintenance, this information helps with the dimensional assessment of components.

Measurement does not replace a complete diagnosis or consulting the technical procedures.

Question 2 — Answer C

One inch equals exactly 25.4 mm.

This relationship is essential for converting dimensions between the metric and imperial systems.

Question 3 — Answer B

The main scale shows 20 mm.

The sixth vernier division, on a 0.05 mm instrument, corresponds to:

Adding:

Question 4 — Answer C

The reading is obtained by adding the indications:

It is important to check the half-millimeter mark, because ignoring it causes a reading error.

Question 5 — Answer C

The dial indicator allows small variations in displacement relative to a reference to be assessed.

That is why it is used in certain runout, end play and position variation checks.

Question 6 — Answer B

The bore gauge is used to compare inside diameters.

In engine cylinders, it helps investigate dimensional variations at different heights and directions.

Question 7 — Answer B

The difference is calculated by subtracting the smaller diameter from the larger:

The 0.04 mm difference can be used to assess the out-of-roundness of the measured section.

Question 8 — Answer A

The feeler gauge has blades of known thickness, used to check certain clearances between surfaces.

Correct use depends on the maintenance procedure.

Question 9 — Answer C

The total dimensional tolerance is the difference between the maximum and minimum limits.

Question 10 — Answer D

Resolution relates to the smallest perceptible variation in the instrument’s indication.

Accuracy relates to how close the result is to the true value of the quantity.

A high-resolution instrument can still have measurement errors.

53. Assessment summary table

54. Conclusion: the importance of automotive metrology

Metrology is a fundamental skill for professionals who work in the maintenance, inspection and reconditioning of automotive components.

Throughout this course, you studied systems of units, metric and imperial conversions and how the main dimensional measuring instruments work.

You learned to interpret caliper and micrometer readings, understand the applications of the dial indicator and bore gauge, check certain clearances and analyze dimensional variations.

You also learned fundamental concepts such as resolution, repeatability, accuracy, calibration, tolerance, clearance and interference.

The main lesson is that a measurement should not be analyzed in isolation.

The result must be obtained with a suitable instrument and correct procedure, and compared with the component’s technical limits.