1. CH 6.4
Measuring Tools

2. Introduction (1 of 2)
Tools and equipment are very important to an efficient and effective shop operation.
Provide means for work to be undertaken on vehicles
Purchase, use, and maintenance is very important to overall performance of any shop.

3. Introduction (2 of 2)
Always use tools and equipment the way they are designed to be used.
Identify the most effective tools to do the task.
Inspect the tool before using it.
Use it correctly.
Clean and inspect it after you use it.
Store it in the correct location.

4. Measuring Tapes (1 of 3)
A flexible type of ruler and common measuring tool
Most common is a thin metal strip about 0.5″ to 1″ (13 to 25 mm) wide.
Rolled up inside a metal housing

5. Measuring Tapes (2 of 3) Have a spring return mechanism
Can be of various lengths
16′ or 25 ′ (5 or 8 m) is very common.

6. Measuring Tapes (3 of 3)
Measuring tape is pulled from housing to measure items.
Spring return winds it back into the housing.
Housing usually has built-in locking mechanism.

7. Steel Rulers Made from steel Commonly 12″, 24″, and 36″ lengths
Used like a ruler
Can rest it on its edge so markings are closer to material being measured
Protect from damage by storing carefully.
Never take measurements from the very end of a damaged steel rule.

8. Outside, Inside, and Depth Micrometers (1 of 13)
Precise measuring tools designed to measure small distances
Can measure down to a resolution of 1/1000 of an inch for a standard micrometer or 1/100 of a millimeter for a metric micrometer
Vernier micrometers equipped with the addition of a vernier scale can measure down to 1/10,000 of an inch or 1/1000 of a millimeter.

9. Outside, Inside, and Depth Micrometers (2 of 13)
Common types of micrometers
Outside micrometer
Inside micrometer
Depth micrometer

10. Outside, Inside, and Depth Micrometers (3 of 13)
Outside micrometer has a horseshoe-shaped frame
Built to make sure micrometer holds its shape
Some frames have plastic finger pads so that body heat is not transferred to the metal frame.
The anvil is on one end of the frame.
The other contact point is the spindle.

11. Outside, Inside, and Depth Micrometers (4 of 13)
Micrometer measures distance between anvil and spindle.
Measurement read on sleeve/barrel and thimble
The sleeve/barrel is stationary and has the linear markings on it.
The thimble fits over the sleeve and has the graduated markings on it.

12. Outside, Inside, and Depth Micrometers (5 of 13)
Since the spindle and sleeve/barrel have matching threads, the thimble rotates spindle inside of sleeve/barrel and thread moves spindle inward and outward.
The thimble usually incorporates either a ratchet or a clutch mechanism.
A lock nut, lock ring, or lock screw is used on most micrometers.

13. Outside, Inside, and Depth Micrometers (6 of 13)
Standard micrometers use a specific thread of 40 tpi on the spindle and sleeve.
The thimble will rotate exactly 40 turns in one inch.
The linear markings on the sleeve show each of the .100″ marks between 0″ and 1″ as well as the .025″ marks.
Since the thimble has graduated marks from 0 to 24 (each mark representing 0.001″), every complete turn of the thimble will uncover another one of the 0.025″ marks on the sleeve.

14. Outside, Inside, and Depth Micrometers (7 of 13)
If the thimble stops short of any complete turn, it will indicate exact number of 0.001″ marks past the zero line on the sleeve.
To read a standard micrometer:
Verify micrometer is properly calibrated.
Verify size of micrometer you are using.
Read how many 0.100″ marks thimble has uncovered.

15. Outside, Inside, and Depth Micrometers (8 of 13)
Read how many 0.025″ marks thimble has uncovered past the 0.100″.
Read number on thimble that lines up with zero line on the sleeve.
Total all of the individual readings.

16. Outside, Inside, and Depth Micrometers (9 of 13)
A metric micrometer uses same components as a standard micrometer.
Uses a different thread pitch on the spindle and sleeve
The sleeve/barrel is labeled with individual millimeter marks and half-millimeter marks from the starting millimeter to the ending millimeter, 25 mm away.
The thimble has graduated marks from 0–49.

17. Outside, Inside, and Depth Micrometers (10 of 13)
To read a metric micrometer:
Read the number of full millimeters the thimble has passed.
Check to see if it passed the 0.5-mm mark.
Check to see which mark on the thimble lines up with or is just past.
Total of all the numbers.

18. Outside, Inside, and Depth Micrometers (11 of 13)
If micrometer is equipped with a vernier gauge, you need to complete one more step.
Vernier gauge means it can read down to 1/10,000 of an inch or 1/1,000 of a millimeter.
Identify which of the vernier lines is closest to one of the lines on the thimble.
At the frame side of the sleeve will be a number that corresponds to the vernier line.
It will be numbered 1-0.
Take the vernier number and add it to the end of your reading.

19. Outside, Inside, and Depth Micrometers (12 of 13)
For inside measurements:
Works on same principles as outside micrometer
The only difference is that the scale on the sleeve of the depth micrometer is backward.

20. Outside, Inside, and Depth Micrometers (13 of 13)
Using micrometers
Make sure micrometer and items to be measured are clean and free of dirt or debris.
Make sure micrometer is zeroed.
Never overtighten it.
Never store it with measuring surfaces touching.
When measuring make sure item can pass through micrometer surfaces snugly and squarely.
Always take multiple measurements.

21. Telescoping Gauges (1 of 2)
For measuring distances in awkward spots

22. Telescoping Gauges (2 of 2)
Have spring-loaded plungers
Can be unlocked with a screw on handle so they slide out and touch walls of a cylinder
Screw locks them into position.
Gauge can be withdrawn.
Distance across plungers can be measured with an outside micrometer or calipers to convey the diameter of the cylinder at that point.

23. Split Ball Gauges (1 of 2)
Measure small holes where telescoping gauges cannot fit
Use similar principles as telescoping gauges
Measuring head uses a split ball mechanism.

24. Split Ball Gauges (2 of 2)
Measuring valve guides on a cylinder head for wear
Can be fitted in the bore and expanded until there is a slight drag
Retracted and measured with an outside micrometer
May have a dial or digital measurement scale fitted for direct reading purposes

25. Dial Bore Gauges (1 of 4)
Measure inside diameter of bores with a high degree of accuracy and speed
Can measure a bore directly by using telescoping pistons on a T-handle with a dial mounted on the handle
Combine a telescoping gauge and dial indicator in one instrument

26. Dial Bore Gauges (2 of 4)
Determine if diameter is worn, tapered, or out-of-round according to specifications
Resolution of dial bore is typically accurate 5/10,000 of an inch or 1/100 a millimeter.

27. Dial Bore Gauges (3 of 4) Using dial bore gauges
Select appropriate-sized adapter to fit internal diameter of bore.
Install it to the measuring head.
Fixture is set to size desired and dial bore gauge is placed in it.
Dial gauge bore is then adjusted to proper reading.

28. Dial Bore Gauges (4 of 4) Using dial bore gauges
Hold the gauge in line with the bore and slightly rock it to ensure it is centered.
Read the dial when it is fully centered and square to the bore.
Store a bore gauge carefully in its storage box.
Make sure the gauge is at a 90-degree angle to the bore and read the dial.
Take multiple measurements.

29. Vernier Calipers (1 of 3)
A precision instrument used for measuring outside, inside, and depth dimensions
Has graduated bar with markings like a ruler
A sliding sleeve with jaws is mounted on bar for taking inside or outside measurements.
Measurements on older versions taken by reading graduated bar scales while fractional measurements are read by comparing scales

30. Vernier Calipers (2 of 3)
They are often used to measure length and diameter of bolts and pins or the depth of blind holes.
Newer versions have dial and digital scales.
The dial vernier has main scale on graduated bar, while fractional measurements are taken from a dial with a rotating needle.
Same as any vernier caliper but have a digital scale that reads measurements directly

31. Vernier Calipers (3 of 3) Using vernier calipers
Always store in a storage box.
Make sure the caliper is at right angles to the surface to be measured.
Repeat the measurement multiple times.

32. Dial Indicators (1 of 6)
Have a dial and needle where measurements are read
Have a measuring plunger with a pointed contact end that is spring loaded and connected via housing to dial needle
Dial accurately measures movement of its plunger in and out as it rests against an object.

33. Dial Indicators (2 of 6) Can also measure how round something is
A crankshaft can be rotated in a set of V blocks.
If crankshaft is bent, it will show as movement on dial indicator as crankshaft is rotated.
Senses slight movement at its tip and magnifies it into a measurable swing on the dial

34. Dial Indicators (3 of 6)
Dial indicators normally have either one or two indicator needles.
The large needle indicates the fine reading of thousandths of an inch.
The second needle will be smaller and indicates the coarse reading of tenths of an inch.
Dial indicators can measure with an accuracy of 0.001″ or 0.01 mm.

35. Dial Indicators (4 of 6)
The type of indicator will be determined by amount of movement you expect from component you are measuring.
Must be set up so there is no gap between dial indicator and component to be measured
Most sets contain various attachments and support arms.
Allow for specific configuration

36. Dial Indicators (5 of 6) Using dial indicators
Useful in determining runout on rotating shafts and surfaces
Keep support arms as short as possible when attaching a dial indicator.
All attachments are tightened to prevent unnecessary movement between indicator and component.

37. Dial Indicators (6 of 6) Using dial indicators
The dial indicator plunger is positioned at 90 degrees to the face of the component to be measured.
Always read the dial face straight on.
The outer face of dial indicator is designed so it can be rotated so that zero mark can be positioned directly over pointer.

38. Straight Edges Usually made from hardened steel
Machined so that edge is perfectly straight
Used to check the flatness of a surface
Gap between straight edge and surface can be measured by using feeler gauges.
Sometimes gap can be seen easily with light
Used to measure the amount of warpage the surface of a cylinder head has

39. Feeler Gauges (1 of 4) Used to measure the width of gaps
The clearance between valves and rocker arms
Flat metal strips of varying thickness
Sized from fractions of an inch or fractions of a millimeter
Usually come in sets with different sizes and are available in standard and metric measurements

40. Feeler Gauges (2 of 4) Some gauges come in a bent arrangement.
More easily inserted in cramped spaces
Some gauges come in a stepped version.
The end might be 0.010″ thick while the rest of the gauges is 0.012″ thick.
Works well for adjusting valve clearance

41. Feeler Gauges (3 of 4)
Two or more feeler gauges can be stacked together to make up a desired thickness.
If you want to measure an unknown gap:
Can interchange feeler gauges until you find one or more that fit snugly into gap and total their thickness
When used in conjunction with a straight edge, they can measure surface irregularities in cylinder head.

42. Feeler Gauges (4 of 4) Using feeler gauges
If the feeler gauge feels too loose when measuring a gap, select next size up.
Repeat until the feeler gauge has a slight drag between both parts.
If the feeler gauge is too tight, select a smaller size.
When measuring a spark plug gap, feeler gauges should not be used.

43. Summary (19 of 30) Micrometers can be outside, inside, or depth.
Learn to read micrometer measurements on the sleeve/barrel and thimble; always verify the micrometer is properly calibrated before use.
Gauges are used to measure distances and diameters; types include telescoping, split ball, and dial bore.

44. Summary (20 of 30)
Vernier calipers measure outside, inside, and depth dimensions; newer versions have dial and digital scales.
Dial indicators are used to measure movement.
A straight edge is designed to assess the flatness of a surface.
Feeler blades are flat metal strips that are used to measure the width of gaps.

45. Credits
Unless otherwise indicated, all photographs and illustrations are under copyright of Jones & Bartlett Learning.