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Engineering Graphics

Engineering Graphics. A few highlights. See “A Brief Introduction to Engineering Graphics” in the Resources section of the ME2011 web site See Q01 on the Assignments page for what you need to know for the graphics quiz. Documenting a part requires. 1. SHAPE 2. SIZE 3. MATERIAL 4. TOLERANCE

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Engineering Graphics

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  1. Engineering Graphics A few highlights

  2. See “A Brief Introduction to Engineering Graphics” in the Resources section of the ME2011 web siteSee Q01 on the Assignments page for what you need to know for the graphics quiz

  3. Documenting a part requires... 1. SHAPE 2. SIZE 3. MATERIAL 4. TOLERANCE 5. FINISH

  4. Top Right Front Multiview drawings TOP RIGHT SIDE FRONT “3rd angle projection”

  5. Six Principle views: obey layout

  6. Basic lines (the “alphabet of lines”) Object line Hidden line Center line Dimension line

  7. FRONT FIND THE MISTAKES!

  8. CORRECT DRAWING

  9. Interpreting Center Lines Enough Info? Enough Info?

  10. COULD BE THIS...

  11. OR THIS Centerlines imply symmetry, NOT revolution per se

  12. HERE, ONLY 2 VIEWS NEEDED (Correct drawing)

  13. Find The Mistakes!

  14. Find The Mistakes!

  15. A A SECTIONS YES NO

  16. DIMENSIONING 1. SHAPE2. SIZE3. MATERIAL4. TOLERANCE AND FINISH

  17. 5 5 3 3 2 3 5 5 Dimensioning rules: …find the mistakes.

  18. 6.0 6.0 Design Detail½” thick aluminum block Which is more expensive: A or B and why? A B 4.0 4.1 What if A was 3.9 in width?

  19. www.mcmaster.com

  20. 6 6 2 4 2 2 6 6 Dimensioning Choices& Design Intent If change width of block to 8, what happens to the hole location? B A

  21. Example

  22. TOLERANCES www.efunda.com/processes/machining/drill.cfm www.efunda.com/processes/machining/drill_press.cfm

  23. ½ inch drill bit: +/- .0040 ½ inch reamer: +.0003, -.0000

  24. Representing tolerances

  25. Tolerance stack-up What is min and max height of stack? 14.7515.25 ? 3.0 ± .05 5 high stack

  26. Tolerance Stacking Ans: +/- 0.3 What’s the tolerance (+/-) on dimension x?

  27. .626 .623 .625 .622 • Will all shafts fit into all holes? • A = yes, B = no • What is maximum clearance? • A = .001, B = .002, C = .003, D = .004 Holes and shafts hole shaft .623 .622 .626 .625

  28. { A 0.030 + B 0.003 4.0 - Design Detail Bent aluminum sheet, 1/16” thick A or B: Which is more expensive and why?

  29. Geometric Dimensioning and Tolerancing (GD&T)

  30. 1.000 ±.005 3.000 ±.005 ? ? Traditional tolerancing is ambiguous

  31. .25 ± .01 .25 ± .01 + + Ambiguity… Square deviation Circular deviation

  32. .25 .125 +/- .002 .01 Geometric Dimensioning and Tolerancing • Ideal position of hole. .25, is marked with boxand no +/- notation. • Feature control box shows how close hole is to exact; within circular tolerance zone with diameter .01

  33. Threaded Fasteners What they are and how to indicate on a drawing

  34. ROUND HEADMACHINE SCREW 1/4" DIA 1" LONG 20 THREADS PER INCH Threaded Fasteners (screws, bolts) • Specify diameter, thread, length, head 1/4-20 x 1, RHMS

  35. Head shapes Cap screw Socket head cap screw (SHCS)Set screw Pan Flat Round

  36. Slotted Phillips Torx Driving a fastener Hex cap Hex head (Allen head)

  37. www.mcmaster.com ¼-20, RHMS, slotted, steel

  38. Name the Fastener:

  39. Name the Fastener: Socket Head Cap Screw Socket Head Cap Screw with counterbore

  40. Phillips Flat Head Screw with countersink

  41. O .166 . 75 Holes 19 DRILL – 0.75 DEEP or DEPTH0.75 REF Pix from www.mcmaster.comunless noted

  42. Convention for threaded holes 6-32 THRU TOP FRONT FRONTSECTION

  43. .4219 1.501/2 – 13 1.325 Blind threaded holes 1/2 – 13 x 1.325 DEEP THREAD DEPTH DRILL DEPTH

  44. .562 – 82O CSK, 1.125 .562 1.125 x 82O Countersunk holes

  45. 19 29 14 Counterbored holes 19 DRILL – 29 CBORE, 14 DEEP C-BORE DEPTH

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