Micrometers

Description

This Activity Plan is designedasoneamong manythroughwhich studentswillrotatewithin theAutomotiveServiceTechnician componentof SkillsExploration10–12.

A micrometeris a detailedmeasuring instrument capable ofmakingvery exact measurementsevento 1/1000of an inch. Automotive technicians use micrometers in order to ensure thattheworktheydoisextremely accurate.

Note: Micrometers are expensive,sensitive measuring instruments. Notallschools canaffordtopurchasethem.This activity should be consideredasecondary supplementary activity to beintroducedonly iftools andfacilitiesexist.

LessonOutcomes

The studentwillbe able to measure a variety ofobjects and obtain precisemeasurementstowithin very exactspecifications.

Assumptions

Prior todoing theactivity themselves,students will havebeen given some theory,andtheinstructor will havedemonstrated theproperprocedureofusingamicrometer.

Terminology

Anvil:the shinypartof themicrometerthat thespindle movestoward and that thesampleissetagainst.

Frame:themainsupporting structureof the micrometer.

Indexline: the horizontalline onthe sleeve that isusedas an indicator line for whichmark toreadonthe thimble.

Micrometer:a detailed measuringinstrumentused tomeasure very fine,exactmeasurements.

Spindle: the shiny cylindricalpartof themicrometer that thethimble movestoward the anvil.

Ratchet screw:found on the endofthethimble,used for “final tightening” on an object toget aconsistent measurementfromperson toperson.

Thimble:thepart of themicrometer that is usually turnedwiththe thumb. Thethimble hasgraduatedmarkings.

EstimatedTime

45–60 minutes

RecommendedNumberofStudents

20, basedonthe BCTechnology Educators’Best PracticeGuide, 1–3 students permicrometer.If notenoughmicrometersare available,students couldwork in small groups with each groupmember measuringadifferent object.

Facilities

Automotiveshop

Tools

Micrometers (asmanyaspossible)

Materials

A variety ofsolidobjectsof variousthicknesses. Ideallytheobjectsshould besomesort ofmetalmaterial.

Note: Beforeproceedingthroughthe activity, the instructor shouldbethoroughly familiar withtheincludedResources sectionof theActivityPlan, inparticular theMicrometer Simulatorwebsite.

Resources

MicrometerCaliper—Merriam-WebsterVisualDictionaryOnline

HowtoUse aMicrometer

MicrometerSimulator

Worksheets

•Micrometer Measurement Exercise

•Reading a Micrometer

•MeasurementQuiz

•Micrometer Test

EvaluationGuidelines

Includedis a worksheet thatstudentscanbe given torecord their micrometermeasurements.

2SkillsExploration 10–12

Activity:UsingaMicrometer

1.Find 10–12 metalobjectsaroundthe automotive shop and set themupin an organized,distributedmanner.

2.Haveeach studentmeasure the thickness ofeachobjectand recordit onthe worksheetprovided.

3.Beginbyholdingthe framewith onehand and slowly turning inthe thimblewith the otheruntil the anvil andspindle almost touch theobject.

4.Slowly turnthe ratchet screw until ittightens aroundthe object andbeginsto ratchet(makesa clicking sound).

5.Lock the thimble in placeand readthe micrometer setting.Note: Referto“How to Read aMicrometer” on page5.

6.Recordyourfindings on theMicrometerMeasurementExerciseworksheet on thenextpage.

Thimble

Sleeve

Ratchetscrew

LocknutSpindleAnvil

Frame

Figure1—Micrometerparts

Figure2—Measuringapiston / Figure3—Measuringabrake rotor

MicrometerMeasurementExercise

Name

Date

ThicknessofObject1()ThicknessofObject2( )ThicknessofObject3( )ThicknessofObject4( )ThicknessofObject5( )ThicknessofObject6( )ThicknessofObject7( )ThicknessofObject8( )ThicknessofObject9( )ThicknessofObject10( )

HowtoReadaMicrometer

Reading amicrometertakes practice.

Tolearntoreadthe mike you needtounderstand the thimbleandthe sleeve.

Herewearegoingtolearntoreadthemicrometerbyfiguringoutthemarkings on thethimbleandthesleeve.

10

Index LineSleeve

5

0Thimble

20

15

10

Thesleevedoes notmove. Itlooks likearuler with10 numbers. The spacebetween eachnumber is divided into quarters. As the thimblerotates aroundthissleeve it covers uporreveals the numbersmarkedon the sleeve.

Thethimblehas numbersandmarkings onit from0 to24. Onecomplete revolution ofthethimble (from 0all the way around to 0again)movesthemicrometerexactly0.025 inches.Thuseachrevolutionofthethimblemovesittothenext “quarter” line on thesleeve.

It iseasy to read amicrometerifyou thinkof tmarkings on the sleeve asdollarsandquarterandthethimbleas“pennies”.

Sleeve

12345

Nowitgets alittle easiertoread themike.

Toread themicrometer,simplyaddup the“dollars”,“quarters”and“pennies”inthecorrectorder. See examplebelow.

Thereadingis composedof:

4Large graduations or 4× 0.100=0.400

2Small graduations or 2× 0.025=0.0508Graduations onthe thimble or8×0.001=0.008

=0.458"

6SkillsExploration 10–12

Name:

Reading the Micrometer

1.Writedown the last visible numberbefore the thimble edge on #1.

5

0

2.Count the number of small linesbetweenthenumberidentifiedin#1and the thimble edge. Multiply thenumber of lines by .025.Write theanswerdown on #2.

Index line

Sleeve

Thimble

3.Find the closest number to theindex line on the thimble.

Note:The number must be belowthe Index Line. Each line is worth

1.1.Write the number down in #3.

#1

+

#2

+

#3 Total

Reading the MicrometerAnswerKey

1.Writedown the last visible numberbefore the thimble edge on #1.

5

0

2.Count the number of small linesbetween thenumber identified in#1and the thimble edge. Multiply thenumber of lines by .025.Write theanswerdown on #2.

Index line

Sleeve

Thimble

3.Find the closest number to theindex line on the thimble.

Note:The number must be belowthe Index Line. Each line is worth

0.001.Write the number down in #3.

#1 0.100

+

#2 0.075

+

#3 0.003

Total

0.178

Measurement Quiz

1.2.3.

4.5.6.

1.4.

2.5.

3.6.

Measurement Quiz Answer Key

1.2.3.

4.

1.0.125

2.0.339

3.0.481

5.6.

4.0.063

5.0.033

6.0.198

Micrometer Test

123

155

01 2

15

10ANS

23 4 6

10ANS

5

00

ANS

10

456

78 9

10ANS

5

23 4

10

5ANS

0

456

5ANS

0

789

0

12 3

5

0ANS

20

34 5

20ANS

15

234

0

20ANS

15

101112

01 20

20

15

ANS

67815

10

ANS

34

5ANS

0

131415

455

0ANS

20

010

5

ANS

890

20

ANS

161718

5

1220

15

ANS

6778 9

0ANS

20

10

ANS

5

Micrometer Test Answer Key

123

155

01 2

15.262

10

ANS

23 4 6

10

5

.609

ANS

0.098ANS

10

456

78 9

10.934ANS

5

23 4

10

5.455ANS

0

4565

0

.603

ANS

789

0

12 3

5

0.375

20

ANS

34 5

20.544

15

ANS

234

0

20.420

15

ANS

101112

01 2

0

.248

678

1534

20ANS

15

.837

10

ANS

5.454

0

ANS

131415

455

010

890

.601.032.946

0ANS

20

ANS

5

20ANS

161718

5

1220

6778 910

.292

15

ANS

0.750

20

ANS

.958ANS

5