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Chapter Tests and Problems

ChaPTer 19 PreCision sheeT MeTal DrafTing TesT

INSTRUCTIONS

Answer the questions with short, complete statements or draw-ings as needed.

QUESTIONS

1. Briefly discuss how the term precision sheet metal drafting is used in this chapter is different from the term associated with sheet metal parts used in construction applications.

2. What specific material does the term sheet metal represent?3. Describe how plate material is different from sheet metal.4. Describe sheet metal parts.5. Define flat pattern.6. How can phantom line be used to represent a flat pattern on

a drawing?7. Describe a drawing showing only the flat pattern using rect-

angular coordinate dimensioning without dimension lines and tabular feature.

8. Describe the following precision sheet metal applications: tables, the use of a hole table, bend table, and a drawing showing a flat pattern with manufacturing information ex-tracted to a table.

9. Give an example of bend instructions that mean bend up 908 with a .120 bend radius.

10. Define the bend tangent line and describe how it is drawn.11. Define the centerline of bend and describe how it is drawn.12. Describe how the inside mold line is drawn.13. Describe how the outside mold line is drawn.14. Define bend allowance.15. What is the purpose of a bend allowance calculation?16. Define neutral axis.17. Typically, where is the neutral axis?18. Define the K-factor.19. Describe bend transition.

20. What are bend facets and when are they used?21. Give the purpose of bend relief.22. How is corner relief used?23. Define flange.24. Describe the characteristics of a typical miter joint.25. Define seam.26. Define hem.27. When are hems necessary?28. What is a roll form?29. When is a roll form used?30. Define lancing.31. Define blanking.32. What is a stamping press?33. Describe nesting blanks.34. Name the three dimensioning practices that are commonly

used for precision sheet metal drafting applications.35. Describe undimensioned drawings.36. Give the basic function of grid lines.37. Describe dimensional accuracy points.38. How are registration marks used in the place of grid lines?39. How many registration marks are used and what is their

orientation?40. Show the media note that should be placed on all undimen-

sioned drawings.

ChaPTer 19 PreCision sheeT MeTal DrafTing ProbleMs

INSTRUCTIONS

1. From the given sketch, draw the required views.

2. Include all dimensions needed using the specified dimen-sioning system and correct ASME dimensioning standards.

3. Use an appropriate sheet size, border, and ASME standard sheet blocks.

4. Include the following general notes at the lower-left corner of the sheet .5 in. each way from the corner border lines:

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NOTES:1. DIMENSIoNING AND TolErANcING pEr ASME y14.5-2009.2. rEMovE All BUrrS AND SHArp EDGES.

Additional general notes can be required, depending on the specifications of each individual assignment. Use the following for tolerances for unspecified inch values. A tolerance block is recommended as described in chapter 2.

Unspecified Tolerances

Decimals in.

X 6.1

XX 6.01

XXX 6.005

ANGULAR 6309

FINISH 125 µin.

For metric drawings, provide a general note that states TolEr-ANcES For UNSpEcIFIED DIMENSIoNS coMply WITH ISo 2768-m. provide a general note that states SUrFAcE FINISH 3.2 µm UNlESS oTHErWISE SpEcIFIED.

(00.000)

(00.

000)

(.81

2)

(5.8

12)

(6.6

25)

(1.875)

(3.500)

(5.125)(UP 908 @ .250 R)

(UP 908 @ .250 R)

(7.000)

2X Ø(.406)

FLAT PATTERN(SCALE .50X)

SIDE OFTANK REF

2X Ø .416.396

2X.281.218 Ø .030 A

AB

C

B C R

6.6566.593

5.000

3.5313.468

.843

.812

1.750

2.0311.968

PRECISION SHEET METAL DETAIL DRAWINGS

Part 1: Problems 19.1 Through 19.12

PROBLEM 19.1 Drawing displayed in form view and flat pattern (in.)

part Name: Mounting Bracket

Material: .23 THK 5086-H32

Courtesy TEMCO

Drafting templates

To access CADD template files with predefined drafting settings, go to the Student Companion Website, select Student Downloads and Drafting Templates, and then select the appropriate template file.

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(00.000)

(00.

000)

(.43

7)

(1.0

62)

(1.5

00)

(1.000)

(1.125)

(1.750)

(2.750)

1.062

.437

.625

1.250

.031[

1.7811.718

1.031.968

2X .312.250 [ 2X (.281)[

1.5311.468

UP 908 @ SHARP R

B

A

A B

PROBLEM 19.2 Drawing displayed in form view and flat pattern (in.)

part Name: Bracket

Material: 14 GA GAlv crS

Courtesy TEMCO

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PROBLEM 19.3 Chassis layout (in.)

part Name: chassis

Material: Aluminum

Given: The engineer’s rough sketch of a computer component chassis.

Do the following using correct ASME standards:

1. Make a flat pattern drawing of the given chassis on properly sized sheet. Full scale is recommended.

2. Use arrowless tabular dimensioning from the given datums.

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000 000.250 .250

1.750 2.00

5.031

8.00

10.125

AAC

DC

000.500.625

5.875

.125 THK

10.2

50

000 .5

00 3.12

5 7.12

5

8.75

0

10.6

2512

.625

14.0

00

2.50

4.8756.5007.125

3.25

4.375

2X R

.250.500

.125.250

DETAIL D

BEND RADIUS = .062

A

A

A

AA

AB

B

908

PROBLEM 19.4 Chassis layoutGiven: The engineer’s rough sketch of a computer component chassis.

Do the following:

1. Make a flat pattern drawing of the given chassis on a properly sized sheet. Full scale is recommended. Establish the flat pattern layout dimension by bend allowance calculations. Show all math formulas and calculations on another paper.

2. Use arrowless tabular dimensioning from the given datums.

Dimensioning Table

hole symbol hole Diameter Depth Quantity

A .123 Through 9

B .230 Through 2

C .469 .030 2

D See detail D Through 1

3. Standard dimensioning is needed for the total length of flat pattern and a dimension from one datum to the bend line in the flat pattern.

PROBLEM 19.5 Display of part in form view with flat pat-tern shown as phantom line (in.)

part Name: Formed plate

Material: Hc-112 6 mm THK

Problem based on original art courtesy Hyster Company.

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PROBLEM 19.6 Display of part in form view and in flat pattern (in.)Given the following engineer’s layout, draw the flat pattern and the formed view. Use geometric dimensioning and tolerancing as shown.

part Name: Mounting Bracket

Material: 11 GA A569

Courtesy TEMCO

FLAT PATTERN

FORM VIEW

(3.546)

1.125

.562

1.6632X

(1.882)

2X (2.015)

2.250

(5.211)

2X R .281.218

R

2X .125

.075

2X .448.436

.572

.562 ¥

2X R.218.156

10X R .156.093

2X (1.812)

9.0318.968

1.2811.218

UP

908

@ .1

87R

UP

908

@.1

87R

2X R8.8768.814

1.656

2.0311.968

3.5933.531

7.1257.062

X

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1.891

3.783

2.641

5.283

R.5004X Ø1.0152X Ø.280

.750

1.500

DOWN 180° R.525CLB

SEE FOLDED VIEW

(R.525)BEND

(1.050)

PROBLEM 19.7 Display of 3-D part model, part in form view and with flat pattern (in.)

part Name: U-Strap

Material: 14 GA ASTM A366

Draw the 3-D model, formed views, and flat pattern using unidirectional dimensioning.

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PROBLEM 19.8 Flat pattern (in.)

part Name: Bracket

Material: 11-gauge (.1196 in.) SAE 1040 steel

The bend radius is equal to the thickness of the material.

Draw the flat pattern using unidirectional dimensioning.

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PROBLEM 19.9 3-D model, flat pattern, and punch ID (in.)

part Name: Mounting Stand

Material: 11-gauge (.1196 in.) ASTM 525

Draw the 3-D model and the flat pattern using rectangular coordinate dimensioning without dimension lines. Use the punch identification and draw the punch details.

DETAIL PUNCH ASCALE 2 / 1

A

DO

WN

90°

R.1

20

DOWN 90° R.120

DO

WN

90°

R.1

20

4X PID A

DOWN 90° R.120

.000

1.89

6

.100

2.89

6

8.89

6

11.6

92

11.7

92

13.6

88

.000

1.896

.100

1.896

5.896

7.692

7.792

9.688

1.000

3X R

1.000

1.000

2.000

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PROBLEM 19.10 3-D model, flat pattern, and punch ID (in.)

part Name: Support Bracket

Material: 11-gauge (.1196 in.) ASTM 304

Draw the 3-D model and the flat pattern using rectangular coordinate dimensioning without dimension lines. Use the punch identification and draw the punch details.

.000

.380

.500

.750

1.500

2.250

2.500

2.620

3.000

.000

.625

1.32

1

1.51

6

2.92

7

3.00

0

3.69

3

4.32

3

2X PID 67495B

PID 67654A

CLBBDN 90° X R.120

CLB BUP 90° X R.120

.0650

.0325

Ø.4680R.00704X

.2000

PUNCH 67495BSCALE 2:1

2X R

.5000

1.0000

PUNCH 67654ASCALE 2:1

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PROBLEM 19.11 3-D model and flat pattern (in.)

part Name: left outer Tri-bracket

Material: 18-gauge ASTM 366

4X Ø.250 WELDHOLE

DOWN 90° R.075

DOWN 90° R.075

3X R.508 MIN

1.070

.732

3.543

2.155

4.290

4.574

.986

.582

4.598

.520

45°

60°

1.694

1.252

4.608

3.800

.989

4.919

5.227

5.270

1.070.986

.582 .520

45°

30°

Ø1.015 MIN

Draw the 3-D model and the flat pattern using unidirectional dimensioning.

Courtesy 2-Kool Inc.

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PROBLEM 19.12 part in form view and with flat pattern (in.)

part Name: Fender Foot rest

Material: 18-gauge ASTM 366

Draw the form views and the flat pattern using unidirectional dimensioning.

Courtesy 2-Kool Inc.

R.048 MIN(BEND 2X )

3.500( )

3.834

1.6252X

2.2222X

BEND DOWN 90° X R.048

BEND DOWN 90° X R.048

R.508 MIN4X

3.417

1.7094.445

.2152X

8.000

3.250

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MATH PRObLEMS

Part 2: Problems 19.13 Through 19.18

Find the bend angle for each of the following figures:

PROBLEM 19.13 (in.)

PROBLEM 19.14 (in.)

PROBLEM 19.15 (in.)

PROBLEM 19.16 (in.)

PROBLEM 19.17 (in.)

PROBLEM 19.18 (in.)

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