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Reading Technical Drawings Foundations of Manufacturing.

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Presentation on theme: "Reading Technical Drawings Foundations of Manufacturing."— Presentation transcript:

1 Reading Technical Drawings Foundations of Manufacturing

2 Dimensioning Systems  Four different systems of dimensioning used in U.S.  Fractional inch  Decimal inch  Dual dimensioning  SI Metric

3 Dimensioning Systems

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8  Fractional type steel rules divided into units of:  1/16  1/32  1/64  Major graduation accentuated by longer lines  Some have small numbers printed adjacent to lines

9 1.3/4 Record the scale length identified by 1 Scale Reading Quiz 1

10 2.1 5/8 2 Scale Reading Quiz 1 Record the scale length identified by

11 3.2 7/16 3 Scale Reading Quiz 1 Record the scale length identified by

12 4.3 3/16 4 Scale Reading Quiz 1

13 5.3 15/16 Scale Reading Quiz 1 Record the scale length identified by 5

14 Decimal Scales Subdivided into units of 1/10, 1/20, 1/50, or 1/100 in. 1/50 is sufficient for most applications

15 Decimal Scales Closer measurements require using micrometer, vernier or dial calipers Major graduations are accented by longer lines- usually every 1/10 in. Popular scales graduation style has.04 and.06 increments slightly longer than.02 and.08 Reads faster, more recognizable

16 Decimal Scales

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20 Scale Reading Quiz Record the scale length identified by... 1

21 Scale Reading Quiz Record the scale length identified by... 2

22 Scale Reading Quiz Record the scale length identified by... 3

23 Scale Reading Quiz Record the scale length identified by... 4

24 Scale Reading Quiz Record the scale length identified by... 5

25 Decimal Dimensioning Drawing may be dimensioned using two- or three-place decimals Amount of tolerance is determined by number of decimal places

26 Decimal Dimensioning.50 may have tolerance of ± may have tolerance of ± may have tolerance of ±.0001

27 Decimal Dimensioning Converting fractions to decimals-results in too many decimal places Need to round off those numbers to desired places

28 Decimal Dimensioning  Rule #1-When the figure following the last digit to be retained is greater than 5--- increase the last number by one .016 becomes.02 .047 becomes.05 .078 becomes.08

29 Decimal Dimensioning  Rule #2-When the figure following the last digit to be retained is less than 5---retain the last number . 031 becomes.03 .062 becomes.06 .093 becomes.09

30 Decimal Dimensioning  Rule #3-When the figure following the last digit to be retained is exactly 5 and the figure to be retained is odd--- increase the last number by one . 375 becomes.38 .875 becomes.88

31 Decimal Dimensioning  Rule #4-When the figure following the last digit to be retained is exactly 5 and the figure to be retained is even--- retain the last number . 125 becomes.12 .625 becomes.62

32 Decimal Dimensioning

33 Decimal Rounding Quiz = = = = = = =

34 Decimal Rounding Quiz = = = = = = =

35 Decimal Rounding Quiz = = = = = =

36 Metric Dimensioning Metric increment of measure is millimeter Will be noted if different Convert a metric dimension to inches by multiplying it by.03937

37 Metric Dimensioning Conversion charts are available to provide converted dimensions Metric scales are available and can be used-eliminating need for conversion

38 Metric Dimensioning  Metric scales  Have graduations every millimeter of half-millimeter  Designated “mm” or “1/2 mm”  Every fifth millimeter is accentuated by a longer line  Every tenth millimeter is identified by a number

39 Metric Dimensioning

40 Scale Reading Quiz mm Record the scale length identified by 1

41 Scale Reading Quiz mm Record the scale length identified by

42 Scale Reading Quiz mm 3 Record the scale length identified by

43 Scale Reading Quiz mm 4 Record the scale length identified by

44 Scale Reading Quiz mm 5 Record the scale length identified by

45 Blueprints  Blueprinting-Term can be interpreted as  Drawing  Picture  Contains information  Required sizes  Tolerances  Essential requirements  Notes and instructions

46 Engineering Drawings Original drawing made by drafter or engineer Prints are referred to as engineering drawings Also referred to as blueprints (more common term)

47 Engineering Drawings  Standardized drawings  “A” size is 8 ½ x 11 inches  “B” size is 11 x 17 inches  “C” size is 17 x 22 inches  “D” size is 22 x 34 inches  “E” size is 34 x 44 inches

48 Engineering Drawings

49 Title Blocks  Each drawing contains a Title Block  Drawing number is most prominent lettering in title block  Lettered larger to stand out  Scale determines the size of the object drafted

50 Title Blocks  Mechanical drawings may be reduced to  Half size  Quarter size  One eighth size

51 Title Blocks  Mechanical drawings may be enlarged  Double  Four times  Ten times

52 Title Blocks Half scale---1/2, 1:2, or ½”=1” Twice scale-2/1, 2:1, 2-1, 2”=1” or 2X Arrangement of numerals indicates relationship

53 Title Blocks  Refer to scale as the “Do Scale”  “D” stands for the drawing  “O” stands for the object  Sale of 1:2 means  The drawing is 1 inch  Object is 2 inches  A “Do Scale” of 2:1 means  The drawing is 2 inches  The object is one inch or one half the drawing size

54 Title Blocks

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58 Drawing Notes  Local notes-apply to specific item or area  Use leaders  Direct notes to point of application  General notes apply to whole drawing or product  Machining  Heat treat  Material  Tolerances

59 Drawing Notes Abbreviations are used in notes Keep them brief

60 Drawing Notes-General (Example) UNLESS OTHERWISE SPECIFIED 1. METRIC UNITS ARE MILLIMETERS 2. FILS & RNDS ARE.12R 3. PART SYM ABOUT CL

61 Single-View Drawings  Sometimes adequate to describe object  Material thickness is listed

62 Detail Drawings  “Production drawings” and “working drawings” are general terms  Includes all types of engineering drawings

63 Detail Drawings  Detail drawings include  Sufficient number of views  Dimensions  Notes  Other pertinent information

64 Centerlines

65 Centerlines  Intersecting centerlines drawn through each hole  Used for location- centerlines are extended outside view and dimensions are added  Radii are the same-often share a common axis- common design practice

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67 Diameters and Radii

68  Internationally recognized symbol for diameter   Use in place of the abbreviation DIA  Number of holes indicated

69 Diameters and Radii  Overall dimensions can be calculated  Remaining material around hole can be calculated

70 Diameters and Radii  Remaining material around hole can be calculated

71 Break Lines  Permits removal of a portion of view  Paper size is smaller  Drawing scale can get smaller  Portion removed must be uniform in shape

72 Break Lines Drawing is full size and does not require a “B” size drawing

73 Break Lines

74 Cylindrical Break

75 Short Break

76 Long Break

77 Typical Dimensions  Entered after a dimension  Means all other similar dimensions are same as one marked “TYP”  Eliminates repetition of dimensions  Saves on drawing space

78 Symmetry  Indicated by note  Indicated by view’s centerline carrying abbreviation

79 1. What is the part number? 11A001 Thermostat Gasket

80 2. What is the name of the part? Thermostat gasket Thermostat Gasket

81 3. What is the drawing size? (A, B, or C) A Thermostat Gasket

82 4. What scale is the drawing? 1:1 Thermostat Gasket

83 5. Use words to explain the answer to question 4. Actual size Thermostat Gasket

84 6. How thick is the part?.06 Thermostat Gasket

85 7. Is the part symmetrical? Yes Thermostat Gasket

86 8. Which system of dimensioning was used? (Refer to page 21.) Decimal Thermostat Gasket

87 9. What is the fractional equivalent of the center hole size? 2 3/16 Thermostat Gasket

88 10.What is the fractional equivalent of the mounting hole spacing? (Refer to the equivalency chart, page 25.) 3 5/8 Thermostat Gasket

89 11. Calculate the longest overall dimension of the part Thermostat Gasket

90 12. Calculate the overall dimension of the part (height.) 2.88 Thermostat Gasket

91 13. Calculate the material remaining between the large hole and the nearest outside edge..345 Thermostat Gasket

92 14. Calculate the material remaining between the small hole and the nearest outside edge..155 Thermostat Gasket

93 15. Calculate the material remaining between the large hole and the nearest small hole..56 Thermostat Gasket


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