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PRECISION MEASUREMENT

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Precision Instruments Explained

• MICROMETERS

• CALIPERS

• DIAL INDICATORS

• GAGE BLOCKS

• FEELER GAGE

How Precise Do I Need To Be ?

.001Tenths Thousands

We need to be able to accurately measure parts to 1/1000 of an inch or as a decimal - .001

Hundreds

Decimal to Fraction Conversions

.125 – 1/ 8”

.250 – 1/ 4”

.375 – 3/ 8”

.500 – 1/ 2”

.625 – 5/ 8”

.750 – 3/ 4”

.875 – 7/ 8”1.00 – 1”

.0625 – 1/ 16”

.1875 – 3/ 16”

.3125 – 5/ 16”

.4375 – 7/ 16”

.5625 – 9/ 16”

.6875 – 11/ 16”

.8125 – 13/ 16”

.9375 – 15/ 16”

Micrometers

Micrometer Set 1” To 6”

Micrometer Parts

Ratchet ScrewThimbleThimble ScaleBarrelBarrel ScaleFrameSpindleAnvil

Micrometer Standards

Zeroing A Micrometer

To zero micrometer scale use spanner wrench, place it in small hole as shown and turn

Divisions

0.025” Division

0.100” Division

0 1 2 3

0

0.001” DivisionBarrel

ScaleThimbleScale

Reading a Micrometer

• Observe the greatest 0.100-inch division on the barrel scale.

• Observe the number of 0.025-inch divisions on the barrel scale.

• Add the thimble scale reading (0.001-inch division) that coincides with the horizontal line on the barrel scale.

• Observe the greatest 0.100-inch division on the barrel scale. (three 0.100” = 0.300”)

0 1 2 3 10

5

Reading a Micrometer

• Observe the number of 0.025-inch divisions between the 0.300-inch mark and the thimble. (two x 0.025” = 0.050”)

0 1 2 3 10

5

Reading a Micrometer

• Add the thimble scale reading that coincides with the horizontal line on the barrel scale. (eight 0.001” = 0.008”)

0 1 2 3 10

5

Micrometer reading0.300”

0.050”

0.008”0.358”

+

Reading a Micrometer

Types Of Calipers

Venier

Dial

Digital

Parts Of A Caliper

Dial .001

Depth Gage

Bar Scale

Inside Measuring Jaws

Outside Measuring Jaws

0 1

10

20

30

405

0

60

70

8 0

90

0

0.100”1.000” 0.010” 0.001”

DivisionsReading Calipers

Reading Calipers

• Observe the greatest 1.000” division

0 1

10

20

30

405

0

60

70

8 0

90

0

1.000”

0 1

10

20

30

405

0

60

70

8 0

90

0

•Observe the greatest 0.100” (0.100” = 0.600”)

0.600”

1.000”0.600”

Reading Calipers

•Observe the greatest 0.010” (0.010” = 0.000”)

0.000”

0 1

10

20

30

405

0

60

708 0

90

0

1.000”0.600”0.000”

Reading Calipers

•Observe the greatest 0.001” (0.001” = 0.005”)

0 1

10 20

30

405

0

60

708 0

90

0

0.005”1.000”0.600”0.000”0.005”+1.605”

Reading Calipers

Dial Indicators

1/2”, 1”, AND 2” TRAVEL

Dial Indicator Parts

BezelPointerDialGraduationsShankStemContact

Dial Indicator Scale

EACH DIVISION = 1\1000 =.001 INCH

Dial IndicatorMounted On Magnetic Base

Dial Indicator

• Mounted on a support• Size range from 1 inch

to 4 1/2 inches in diameter

• Balanced scale (read plus or minus)

• Continuous scale (dimensions)

• Scales range from .002” to 1.000” This setup is used to check for

end play on a crankshaft.

Gage BlocksGage blocks are very accurate measuring standards to 1\1,000,000 in.

Gage Blocks

Five Individual Gage Blocks From Set

Ringing Blocks Together

Ringing Two Blocks Together So They Attach

Gage Blocks

Gage Blocks Rung Together To Give An Accurate Size

Feeler Gage

• Thin strips of steel or brass

• Available in various thickness

• Measured in thousandths of an inch

• Millimeter

Here a feeler gauge is checking the valve adjustment

Feeler Gage

Measuring Tools Summary

• MICROMETERS• CALIPERS• DIAL INDICATORS• GAGE BLOCKS• FEELER GAGES

Measuring Questions• NAME 5 TYPES OF MEASURING TOOLS.• NAME THE TWO SYSTEMS USED TO MEASURE.• WHAT 3 MEASURING JOBS CAN A CALIPER DO?• HOW IS A FRACTION CHANGED TO A DECIMAL?• WHAT ARE GAGE BLOCKS AND HOW ARE THEY USED?• WHAT IS A DIAL INDICATOR AND ITS USES?• NAME THE PARTS OF A MICROMETER.• LIST 5 PRECAUTIONS TO PRACTICE WHEN USING

PRECISION MEASURING TOOLS.