aurt225667a use and maintain measuring equipment – part 1 1 © commonwealth of australia...

AURT225667A USE AND MAINTAIN MEASURING EQUIPMENT – PART 1 1

© Commonwealth of Australia 2011 AURT225667A Use and maintain measuring equipment - Part 1

AURT225667A

Use and maintain measuring equipment

– Part 1

AUR30405 CERTIFICATE III IN AUTOMOTIVE MECHANICAL TECHNOLOGY



Introduction to measuring

1

Measuring must be done accurately.

Measure and adjust – •spark plug gaps•valve clearances•fuel pressures•what else?

Measure size, fit, clearance, pressure, temperature or other specification.



Measuring accurately

2

Measuring tools can easily be damaged. Damaged tools are inaccurate.•Don’t drop or mis-handle them.

•Check them regularly for accuracy.

To measure accurately:• Handle measuring tools correctly• Select measuring tools that are accurate for the work• Check measuring tool is reading accurately.



3

Measuring equipment

steel rule straight edge

feeler gauge

micrometer

dial indicatorvernier calliper

outside calliper



Manual lifting safety

Measuring sometimes involves working with heavy or awkward machinery or parts eg cylinder heads, cylinder blocks and crankshafts. •Use stands, chocks, or “V” blocks to stop parts moving.

•When lifting or moving heavy parts - ask for help, or use a crane or lifting equipment.



Flat Feeler Gauge • Hardened steel blades of different

thicknesses• Each blade marked with its size in

millimeters and/or inches.

Useful for:

• measuring small slots or grooves•measuring clearances of machinery, eg valve or tappet clearance.



Wire feeler gauge

• Has several wires, each with a different thickness

• Designed to check and adjust spark plug gaps

• Has a gap adjuster, to bend the earth electrode on the spark plug.



Straight edge

• Made from a thick wide strip of alloy steel

• Hardened and ground to form two parallel flat edges

• Usually between 150mm to l000mm in length.

• Can be used for checking the flatness of a surface.

• Used to measure the gap between the straight edge and a surface eg on a cylinder head.



Steel rules

• Used for general measurements• Graduated in millimeters and

centimeters.

Care• Handle carefully.• The zero end of the rule must be• Kept in perfect condition to

maintain accuracy.



Measuring with a steel rule

To measure length:• Place the end of the ruler flush with start of material.• Look at exact place on rule where material ends.• Read length on ruler scale.

• Generally measure to an accuracy of 1 mm.

• Some measure to an accuracy of 0.5mm.



Caring for callipers

Callipers are precision instruments. Protect from damage:• Keep in own protective cases

• Never keep loose in a toolbox with other tools

• Never drop or knock sharply

• Never use excessive force when measuring

• Clean metal parts with a slightly oily rag

• Clean plastic parts with a dry rag

• Inspect jaws for damage

• Replace batteries regularly in digital callipers.



Sliding jaw callipers

• Have own measuring scales built in• Very accurate - some can measure to 0.01mm (1/100 of a millimetre)

Dial-type callipers Digital callipers

Vernier callipers



Using sliding jaw callipers

Internal jaws measure gaps/ internal diameters.

Depth gauge measure steps/ heights/ depth of holes.

External jaws measure outside diameters/ thickness/ length.



Using dial-type callipers

1. Clean jaws and close completely.

2. Check dial = 0. Adjust if necessary by rotating & locking dial.

3. Gently close jaws on part being measured. When “feel” is correct, lock slide.

4. Read number of whole millimetres on left of reference face.

5. Note dial reading, and add it to whole mm reading.



Using digital callipers• Can make measurements as small as 0.001mm (1/1000 millimetre)• Measurements shown directly on digital display• Display can switch between metric and imperial measurements.

1.Clean & close jaws

2.Press ON button

3.Press ZERO button

4.Check display reads zero, then make measurement.



The vernier calliper• Has a special vernier scale marked on the sliding jaw• Measures down to 0.02mm (2/100 millimetre)

Outside jaws

Inside jaws

Sliding jaws

Locking screw

vernier scale

Main scale

Depth gauge



Using the vernier calliper

1. Before measuring, close jaws and check that main scale zero mark lines up exactly with vernier scale zero mark.

2. Adjust jaws.

3. You may need to gently “rock” the jaws to get the right feel – not too tight, not too loose.

4. Lock the slide.



Using the vernier calliper cont’d

5. Read number of whole millimetres on main scale, before the vernier zero

6. Look for a vernier scale graduation which lines up exactly with any graduation on the main scale

7. Read fraction number on vernier scale where the marks line up

8. Add fraction to whole millimetres to get final measurement.

Example: 16.00 whole mm + 0.38 mm on vernier = 16.38 mm

16 whole mm

0.38 mm

18



Micrometers

1. The outside micrometer • Measures width and length • Used for precise measurements eg

reconditioning an engine, measuring pistons, valves, crankshafts etc.

• Use to take very accurate measurements• 3 types - may look different but all use the same

principle.1. Outside micrometer2. Inside micrometer3. Depth micrometer



Micrometers

2. Inside micrometer • measures the inside of holes or

bores.

3. Depth micrometer• measures the depth of holes/

grooves/ recesses and the height of shoulders.



Caring for micrometers

Precision instruments must be treated carefully.

Always:

•Clean face of spindle and anvil.

•Check zero reading before use.

•Avoid dirty or rough components.

•Do not adjust micrometers unless trained to do so.

•After use - clean, lightly oil, and store in a protective box.



The outside micrometer

This micrometer can measure:

•between 0 - 25 millimeters (25mm)

•to an accuracy 1/100 of a millimeter (0.01mm ).

Measuring range = The minimum and maximum distance it can measure. It is marked on the frame.



Outside micrometer cont.

Can accurately measure the distance between two machined surfaces eg. - thickness of a shim washer - diameter of a crankshaft journal.

This micrometers has a range of 50 – 75mm.

Micrometers should have no zero error. They are tested with a special, very accurate test piece.



More micrometers

Vernier micrometer • has an extra vernier scale on the

sleeve• can measure down to 0.001mm

(1/1000 of a millimetre).

Digital micrometer •has a display which shows the measurement•may have a conventional scale as well.



Using the outside micrometer

Hold micrometer by frame with your left hand.

Open micrometer and clean anvils with a clean cloth.

Gently close micrometer with ratchet until anvils are touching

or use a test piece.

Look at the scales - they should both read zero.

Check accuracy



Reading the micrometer scale

The sleeve is marked with numbered graduations = whole millimetres.

Sleeve also has half millimetre graduations marked.

Around the thimble - 50 graduations, beginning and ending at 0.



Reading the micrometer scale

One full turn of the thimble opens the micrometer by exactly 0.50mm. A “half mm” graduation is just visible on the datum line.

Two full turns opens the anvils by exactly 1.00 mm.The 1 mm graduation is just showing on the datum line.



Reading the micrometer scaleRemember – 1 thimble division = 0.01 mm.

To get the final measurement:

1. Note the number of whole millimetres visible on the datum line.

2. Add any half millimetres showing on the datum line.

3. Add the number of thimble graduations lined up with the datum line.

0.01mm



Reading the Micrometer Scale

Example 1

4 whole mm showing = 4.00 mm1 half mm showing = 0.50 mm5 indicated on the thimble= 0.05 mm

TOTAL = 4.55 mm

5 whole mm showing = 5.00 mm1 half mm showing = 0.50 mm12 indicated on the thimble = 0.12 mm

TOTAL = 5.62 mm

Example 2



• Has a face or dial marked in divisions of 0.01 mm (1/100 mm)

• Does not take a direct measurement - shows variations from the original zero setting

• These variations are transferred from the spindle to the pointer.

Dial indicator gaugeAlso called a dial gauge or dial indicator.



Dial indicator

• Used to measure:

- the bend or run-out in a shaft

- the clearance between two parts eg between an engine valve and its guide.

• Must be firmly mounted. A magnetic stand or a stand with a screw clamp is often used.



Setting up the dial indicator

1. Mount dial gauge firmly on its stand

2. Mount stand securely, to prevent damage from dropping or excessive vibration

3. Keep spindle at right angles (perpendicular) to the surface being checked.



Reading the dial indicator1. Read the whole millimetres

from the inner scale (only for absolute measurements)

3. Read the hundredths of millimetres (small divisions on outer scale).

2. Read the tenths of millimetres (numbers on outer scale)



Reading the dial indicator

Step 1

Read the whole millimetres. The short needle is between the 4 and the 5, so the reading is 4.00 mm.Step 2

Read the tenths. The long needle is between the 0.20 and the 0.30 mm, so the reading is 0.20 mm.

Step 3

The long needle is 6 small divisions past the 2, so the reading is 0.06 mm.

ExampleStep 1

Step 2

Step 3



Reading the dial indicator

Step 4

To get the final measurement - add up the measurements from Steps 1, 2, & 3.

Step 1 4.00 mm

Step 2 + 0.20 mm

Step 3 + 0.06 mm

Total = 4.26 mm

4.00 mm 0.20 mm

0.06 mm



© Commonwealth of Australia 2011ISBN: 978-1-876838-44-7

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aurt225667a use and maintain measuring equipment – part 1 1 © commonwealth of australia...

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