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Reading Technical Drawings

Reading Technical Drawings. Foundations of Manufacturing. Dimensioning Systems. Four different systems of dimensioning used in U.S. Fractional inch Decimal inch Dual dimensioning SI Metric. Dimensioning Systems. Dimensioning Systems. Dimensioning Systems. Dimensioning Systems.

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Reading Technical Drawings

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  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

  4. Dimensioning Systems

  5. Dimensioning Systems

  6. Dimensioning Systems

  7. Dimensioning Systems

  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. Scale Reading Quiz 1 • 3/4 Record the scale length identified by 1

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

  11. Scale Reading Quiz 1 • 2 7/16 Record the scale length identified by 3

  12. Scale Reading Quiz 1 • 3 3/16 Record the scale length identified by 4

  13. Scale Reading Quiz 1 • 3 15/16 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

  17. Decimal Scales

  18. Decimal Scales

  19. Decimal Scales

  20. Scale Reading Quiz 2 • .80 Record the scale length identifiedby... 1

  21. Scale Reading Quiz 2 • 1.60 Record the scale length identifiedby... 2

  22. Scale Reading Quiz 2 • 2.50 Record the scale length identifiedby... 3

  23. Scale Reading Quiz 2 • 3.32 Record the scale length identifiedby... 4

  24. Scale Reading Quiz 2 • 3.86 Record the scale length identifiedby... 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 ± .01 • .500 may have tolerance of ± .001 • .5000 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 • .109 = • .125 = • .156 = • .234 = • .438 = • .547 = • .562 = .11 .12 .16 .23 .44 .55 .56

  34. Decimal Rounding Quiz • .641 = • .797 = • .875 = • 1.056 = • 1.672 = • 2.205 = • 2.454 = .64 .80 .88 1.06 1.67 2.20 2.45

  35. Decimal Rounding Quiz • 3.335 = • 3.767 = • 5.555 = • 6.665 = • 7.045 = • 8.885 = 3.34 3.77 5.56 6.66 7.04 8.88

  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 3 • 20 mm Record the scale length identified by 1

  41. Scale Reading Quiz 3 Record the scale length identified by 2 • 35 mm

  42. Scale Reading Quiz 3 Record the scale length identified by 3 • 51 mm

  43. Scale Reading Quiz 3 Record the scale length identified by 4 • 77.5 mm

  44. Scale Reading Quiz 3 Record the scale length identified by 5 • 93.5 mm

  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

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