LEARNING OBJECTIVES - NEMESneme-s.org/CTHSS/Machining Fundamentals/MFIM03.pdf · • The Alphabet...

INSTRUCTIONAL MATERIALSText: pages 29–54

Test Your Knowledge Questions, pages 52–53

Workbook: pages 15–22Instructor’s Resource: pages 57–70

Guide for Lesson PlanningResearch and Development IdeasReproducible Masters:

3-1 Typical Assembly Drawing3-2 Alphabet of Lines3-3 Threads (how depicted on a drawing)3-4 Information on a Typical Drawing3-5 Dual Dimensioning3-6 Metric Drawing3-7 Geometric Dimensioning and

Tolerancing (application of)3-8 Test Your Knowledge Questions

Color Transparencies (Binder/CD only)

GUIDE FOR LESSON PLANNINGThis chapter introduces and explains the

basics of drawings used in industry. Since itwould not be possible to manufacture complexproducts without them, the machinist must

know how to obtain and understand all of theinformation provided on drawings.

With the increasing use of computer-gener-ated machining programs, drawings may notalways be available to the machinist at the workstation. Often times, the machinist only sees a“drawing” on the computer monitor and thecomputer program makes corrections andadjustments or alerts the machinist to possibleproblems. However, the machinist may have torefer to the drawings to determine what adjust-ments and changes are acceptable. For this rea-son, it is of vital importance that a machinist beable to read and understand drawings.

Have students read and study Chapter 3.Review the assignment and discuss the following:

• Importance of drawings to ensure thatparts, no matter where they are made,will be interchangeable and fit properly innew assemblies and in similar assembliesmade at an earlier date.

• Reason for standardized symbols, lines,and figures.

• The importance of the American NationalStandards Institute (ANSI).

• The Alphabet of Lines.

Chapter 3

UnderstandingDrawings

LEARNING OBJECTIVESAfter studying this chapter, students will be able to:� Read drawings that are dimensioned in fractional inches, decimal

inches, and in metric units.� Explain the information found on a typical drawing.� Describe how detail, subassembly, and assembly drawings differ.� Point out why drawings are numbered.� Explain the basics of geometric dimensioning and tolerancing.

57

• Symbols revised by ANSI and the symbolsthey replace.

• Information found on drawings and howit is used.

• Types of drawings used in shops.• Methods used to reproduce drawings.• Drawing sizes.• Geometric Tolerancing and Dimensioning

and why it is used.Emphasize that a machinist:• Always works to the dimensions, toler-

ances, and surface finishes specified on adrawing.

• Never scales a dimension from a drawing.

Technical TermsReview the terms introduced in the chapter.

New terms can be assigned as a quiz, home-work, or extra credit. These terms are also listedat the beginning of the chapter.

actual sizeAmerican National Standards Institute (ANSI)

bill of materialsdual dimensioninggeometric dimensioning and tolerancing revisionsscale drawingsSI Metric US Conventional working drawings

Review QuestionsAssign Test Your Knowledge questions. Copy

and distribute Reproducible Master 3-8 or havestudents use the questions on pages 52–53 in thetext and write their answers on a separate sheetof paper.

Workbook AssignmentAssign Chapter 3 of the Machining Funda-

mentals Workbook.

Research and DevelopmentDiscuss the following topics in class or allow

students to choose topics for individual orgroup projects.1. Make a tracing and reproduce it using the

diazo and electrostatic processes.2. Prepare a display of the microfilming tech-

nique of print reproduction. Include prints,samples of film cards and photographs, ormagazine advertisements illustrating theequipment used to make them.

3. Secure sample prints from industry.4. Secure prints produced by the CAD

(Computer-Aided Design) technique.5. Prepare a display panel that shows a simple

project from print to finished product.6. Prepare transparencies for the overhead pro-

jector that show the title block, parts list, andmaterial list from an actual industrialdrawing. Use them to explain or describe anindustrial drawing to the class. If possible,borrow a sample of the part shown on thedrawing.

7. Contact a local industry and borrow printsof a simple assembly. If possible, also securea sample of the object shown on the print.Develop a display.

TEST YOUR KNOWLEDGEANSWERS, Pages 52–531. d. All of the above.2. language of industry3. one-millionth4. one-millionth5. Use a surface roughness comparison

standard.Profilometer or electronic roughness gage.

6. bilateral7. unilateral8. b. Allowances in either oversize or under-

size that a part can be made and still beacceptable.

9. scale drawings10. a. Showing only a small portion of the com-

plete object.11. They sometimes get lost, damaged, or

destroyed.12. detail13. It shows where and how the parts described

on a detail drawing fit into the completedassembly.

14. Convenience in filing and locating drawings.15. basic16. reference17. A feature control frame is used when a loca-

tion or form tolerance is related to a datum.

Machining Fundamentals Instructor’s Resource58

18.

19. Maximum material condition (MMC) is thecondition in which the size of a featurecontains the maximum amount of materialwithin the stated limits of size. Also referto Figure 3-31.

20. Least material condition (LMC) is the condi-tion in which the size of a feature contains theleast amount of material within the statedtolerance limits. Also refer to Figure 3-32.

WORKBOOK ANSWERS,Pages 15–221. d. All of the above.2. fractional3. English, metric4. Student answers will vary but may include

any four of the following: material(s) to beused; surface finish required; tolerances;quantity of units per assembly; scale ofdrawing; next assembly or subassembly;revisions; the name of the object.

5. Tolerances are allowances, either undersizeor oversize, permitted when machining ormaking an object.

6. roughness comparison7. profilometer8. d. Dimensions should never be scaled off a

drawing.9. b. only a small portion

10. drawings might be lost, damaged, or dest-royed; same print may be needed in differ-ent places at same time

11. d. All of the above.12. Evaluate individually.

13. When the amount of variation (tolerances) inform (shape and size) and position (location)needs to be more strictly defined, it providesthe precision needed to allow for the mosteconomical manufacture of parts.

14. Geometric dimensioning and tolerancing is asystem that provides additional precisioncompared to conventional dimensioning. Itensures that parts can be easily interchanged.

15. They are employed to provide clarity and pre-cision in communicating design specifications.

16. d. All of the above.17. b. basic dimension18. a. reference dimension19. measured size of a part after it is

manufactured20. feature control frame21. Maximum material (MMC)22. Least material (LMC)23. A. Material to be used

B. TolerancesC. QuantityD. ScaleE. Next assemblyF. RevisionsG. Name of objectH. Drawing number

24. A. 3.000″B. 2.000″C. 1.625″D. 0.7503″E. +0.0003″F. 0.266″G. 0.265″H. 0.391″I. Remove burrs. Break sharp edges .010″

Max. Finish 125 all over except as noted.25. A. Clamp, Alignment

B. Full sizeC. B123456D. D45678E. Dual dimensioningF. Aluminum 6061-T4G. 12H. Distance from centerline to flat on top of

part was changed from 1.50″ (38.0 mm)to 1.62″ (41.14 mm).

Chapter 3 Understanding Drawings 59

26. L. 4.25″ (107.85 mm)W. 2.62″ ( 66.54 mm)T. 0.75″ (19.0 mm)

27. 1. 125 [ 3.2 ] all over.2. Break all sharp edges 0.01 [0.5] MAX.3. Dimensions in [ ] are millimeters.

28. A. 1.50″ (38.1 mm)B. 0.500″

29. No standard metric tool available this size.

30. A. 3.25″ (82.45 mm)B. 1/4-20UNC-2C. There is no metric thread this size.D. 0.37″ (9.5 mm)E. 0.26″ (6.7 mm)F. 0.13″ (3.5 mm)G. 0.75″ (19.0 mm)H. +0.001″I. 0.75″ (19.0 mm)J. 1.00″ (25.4 mm)K. 1.62″ (41.14 mm)



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Copyright Goodheart-Willcox Co., Inc. 3-3

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Name: ______________________________________________Date: _______________ Score: ________

1. Drawings are used to:a. Show, in multiview, what an object looks like before

it is made.b. Standardize parts.c. Show what to make and the sizes to make it.d. All of the above.e. None of the above.

2. The symbols, lines, and figures that make up a drawingare frequently called the _____.

3. A microinch is _____ of an inch.

4. A micrometer is _____ of a meter.

5. How can surface roughness of a machined part be checked against specifications on the drawing?

____________________________________________________________________________________

How can it be measured electronically? _________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

6. When tolerances are plus and minus, it is called a _____tolerance.

7. When tolerances are only plus or only minus, it is calleda _____ tolerance.

8. Tolerances are:a. The different materials that can be used.b. Allowances in either oversize or undersize that a

part can be made and still be acceptable.c. Dimensions.d. All of the above.e. None of the above.

9. Drawings made other than actual size are called _____.

10. A subassembly drawing differs from an assemblydrawing by:a. Showing only a small portion of the complete object.b. Making it possible to use smaller drawings.c. Showing the object without all needed dimensions.d. All of the above.e. None of the above.



Understanding Drawings

1. ____________________________

2. ____________________________

3. ____________________________

4. ____________________________

6. ____________________________

7. ____________________________

8. ____________________________

9. ____________________________

10. ____________________________

(continued)

11. Why are prints used in place of the original drawings? ___________________________________

____________________________________________________________________________________

____________________________________________________________________________________

12. The craft worker is given all of the information neededto make a part on a _____ drawing.

13. What does an assembly drawing show? ________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

14. Why are standard size drawing sheets used? ____________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

15. All dimensions have a tolerance except _____ dimensions.

16. Dimensions placed between parentheses are _____dimensions.

17. When is a feature control frame employed? _____________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

18. Sketch the form geometric tolerance symbols and indicate what they mean.


Copyright Goodheart-Willcox Co., Inc. 3-8(continued)

Name ______________________________________________

12. ____________________________

15. ____________________________

16. ____________________________

19. Define the term maximum material condition (MMC). Use a sketch if necessary. _______________

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

20 Define the term least material condition (LMC). Use a sketch if necessary. ________________________________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________


Name ______________________________________________


LEARNING OBJECTIVES - NEMESneme-s.org/CTHSS/Machining Fundamentals/MFIM03.pdf · • The Alphabet...

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Transcript of LEARNING OBJECTIVES - NEMESneme-s.org/CTHSS/Machining Fundamentals/MFIM03.pdf · • The Alphabet...