Blueprint Reading for the Machine Trades, Sixth Edition Unit 2: Dimensioning Systems

1. Blueprint Reading for the Machine Trades, Sixth Edition Unit 2: Dimensioning Systems Russ Schultz and Larry Smith PowerPoint presentation created by LaVonne Vichlach

2. Dimensioning Systems • Four different systems of dimensioning used in U.S. and Canada • 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. Fractional Dimensioning • Always reduce a fraction to its lowest terms • If numerator is even number-it can be reduced • Begin your count from a major graduation close to the reading

10. Fractional Dimensioning

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

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

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

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

15. Scale Reading Quiz 1 • 3 15/16 Record the scale length identified by 5

16. Scale Reading Quiz 1 • 13/16 Record the scale length identified by 6

17. Scale Reading Quiz 1 • 1 ¾ Record the scale length identified by 7

18. Scale Reading Quiz 1 • 2 11/16 Record the scale length identified by 8

19. Scale Reading Quiz 1 • 3 17/32 Record the scale length identified by 9

20. Scale Reading Quiz 1 • 3 31/32 Record the scale length identified by 10

21. Decimal Scales • Subdivided into units of 1/10, 1/20, 1/50, or 1/100 in. • 1/50 is sufficient for most applications • With 50 increments to an inch each increment =.02 in. • Reading between increments-capable of determining closest .01 inch measurement

22. 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

23. Decimal Scales

24. Decimal Scales

25. Decimal Scales

26. Decimal Scales

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

28. Scale Reading Quiz 2 • 1.60 Record the scale length identified by… 2

29. Scale Reading Quiz 2 • 2.50 Record the scale length identified by… 3

30. Scale Reading Quiz 2 • 3.32 Record the scale length identified by… 4

31. Scale Reading Quiz 2 • 3.86 Record the scale length identified by… 5

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

33. Decimal Dimensioning • .50 may have tolerance of ± .01 • .500 may have tolerance of ± .001 • .5000 may have tolerance of ±.0001

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

35. 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

36. 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

37. 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

38. 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

39. Decimal Dimensioning • Rule #3 and #4 are different • Established to even numbers as often as possible • Even numbers are preferred • Decimal numbers divided by two-e.g.-diameter/2 = radius-----results will contain same number of decimal places

40. Decimal Dimensioning

41. Decimal Rounding Quiz .11 • .109 = • .125 = • .156 = • .234 = • .438 = • .547 = • .562 = .12 .16 .23 .44 .55 .56

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

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

44. Metric Dimensioning • Metric increment of measure is millimeter • Will be noted if different • Dual dimensioning system-SI Metric-used in U.S. and Canada • Convert a metric dimension to inches by multiplying it by .03937

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

46. 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

47. Metric Dimensioning

48. Scale Reading Quiz 3 Record the scale length identified by • 20 mm 1

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

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