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TECH 104 – Technical Graphics Communication

TECH 104 – Technical Graphics Communication. Week 10: Working Drawings. TECH 104 – Technical Graphics Communication. First, here’s what we talked about last time… Applying Tolerances. Week 10: Working Drawings. TECH 104 – Technical Graphics Communication. Representing Tolerance Values.

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TECH 104 – Technical Graphics Communication

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  1. TECH 104 – Technical Graphics Communication Week 10: Working Drawings

  2. TECH 104 – Technical Graphics Communication First, here’s what we talked about last time… Applying Tolerances Week 10: Working Drawings

  3. TECH 104 – Technical Graphics Communication Representing Tolerance Values ∙ Tolerance is the total amount a dimension may vary and is the difference between the maximum and minimum limits. (A) Tolerance = .04 (B) Tolerance = .006 ∙ Tolerances are represented as Direct Limits (A) or as Tolerance Values(B). Week 10: Working Drawings

  4. A System is two or more mating parts. TECH 104 – Technical Graphics Communication Important Terms of Toleranced Parts Nominal Size is used to describe the general size (usually in fractions). Basic Size – theoretical size used as a starting point for the application of tolerances (written in decimals). Week 10: Working Drawings

  5. Actual Size is the measured size of the finished part after machining. Limits – the maximum and minimum sizes shown by the tolerance dimension. The large value on each part is the Upper Limit, the small value = Lower Limit. TECH 104 – Technical Graphics Communication Important Terms of Toleranced Parts Week 10: Working Drawings

  6. Allowance – the tightest fit between two mating parts. TECH 104 – Technical Graphics Communication Important Terms of Toleranced Parts (The minimum clearance or maximum interference). Week 10: Working Drawings

  7. Maximum Material Condition (MMC) The condition of a part when it contains the greatest amount of material. TECH 104 – Technical Graphics Communication Important Terms of Toleranced Parts Least Material Condition (LMC) The condition of a part when it contains he least amount of material possible. Week 10: Working Drawings

  8. Piece tolerance The difference between the upper and lower limits of a single part (.002 on the insert in this example, .004 on the slot.). System tolerance The sum of all the piece tolerances. For this example (.006) TECH 104 – Technical Graphics Communication Important Terms of Toleranced Parts Week 10: Working Drawings

  9. TECH 104 – Technical Graphics Communication Fit Types: A Clearance Fit occurs when two toleranced mating parts will always leave a space or clearance when assembled. An Interference Fit occurs when two toleranced mating parts will always interfere when assembled. Week 10: Working Drawings

  10. Functional Dimensioning begins with tolerancing the most important features. TECH 104 – Technical Graphics Communication Functional Dimensioning Then, the material around the holes is dimensioned (at a much looser tolerance). Functional features are those that come in contact with other parts, especially moving parts. Holes are usually functional features. Week 10: Working Drawings

  11. Dimensioned from the left. Dimensioned from the right. TECH 104 – Technical Graphics Communication Occurs when dimensions are taken from opposite directions of separate parts to the same point of an assembly. Tolerance Stack-up AVOID THIS!!! Week 10: Working Drawings

  12. Better still, relate the two holes directly to each other, not to either side of the part. The result will be the best tolerance possible of ±0.005. TECH 104 – Technical Graphics Communication Avoiding Tolerance Stack-up Tolerance stack-up can be eliminated by careful consideration and placement of dimensions. (Dimension from same side). Week 10: Working Drawings

  13. TECH 104 – Technical Graphics Communication Generally, a complete set of Working Drawings for an assembly includes: 1.) Detail Drawings of each non-standard part. Today’s Lecture - Week 10: Working Drawings 2.) An Assembly or Subassembly drawing showing all the standard parts in a single drawing. 3.) A Bill of Materials (BOM). 4. A Title Block.

  14. A Detail Drawing of a Single Part Called a Lever

  15. An assembly drawing normally consists of the following: 1. All parts drawn in their operating position 2. A parts list or Bill of Materials (BOM) 3.Leader lines with balloons indicating all parts. 4. Machining and assembly instructions Assembly Drawing of a Piston & Rod containing 8 parts.

  16. Detail Drawing of the retainer ring used to fasten the rod to the piston.

  17. Multiview Sectioned Assembly Drawing of a Spring Pack containing… Drawing Number Part Numbers

  18. Sectioned Assembly TECH 104 – Technical Graphics Communication Pictorial Assemblies

  19. TECH 104 – Technical Graphics Communication Technical Illustration (Exploded) Assembly Pictorial Assemblies

  20. TECH 104 – Technical Graphics Communication …contain... • Name & Address of Company • Title of the Drawing • Drawing Number • Names and dates of drafters, • checker, issue date , • contract number, etc. • E. Design Approval • F. Additional Approval Block • G. Drawing Scale • H. Federal Supply Code for • Manufacturers • J. Drawing Sheet Size • K. Actual or estimated weight • L. Sheet Number Title Blocks

  21. TECH 104 – Technical Graphics Communication The information normally included in a parts list is as follows: 1. Name of the part. 2. A detail number for the part in the assembly. 3. The part material, such as cast iron or bronze. 4. The number of times that part is used in the assembly. 5. The company assigned part number. 6. Other information, such as weight, stock size, etc. Parts Lists

  22. TECH 104 – Technical Graphics Communication Record any changes - Found in upper-right corner Revision Blocks

  23. TECH 104 – Technical Graphics Communication General tolerance note for inch and millimeter dimensions

  24. ANSI drawing sheets with “zones” located on the border.

  25. TECH 104 – Technical Graphics Communication Tabular Drawings

  26. Also in Today’s Lecture - Week 10: Fastening Devices • Fastening is a method of connecting or joining two or more parts together, using devices or processes. • Mechanical Fastening –Process that uses manufactured devices (Nuts and Bolts) • Bonding – Using material (Glue, Welding) • Forming – Using component shape itself (HVAC, Tupperware, Velcro)

  27. Threaded Fasteners • First Application of a screw thread was developed by Archimedes to lift water. • 1800’s Joseph Whitworth – English Standard Screw Threads • 1864 – US Screw Thread Standard • 1946 – ISO Develops Metric Standard • 1948 – US Develops Unified Standard

  28. Internal Threads Form Chart External Threads Standard Thread Notations:

  29. TECH 104 – Technical Graphics Communication Specifying Tap Drill Size: A Tap is a tool used to make threads in holes. A Die is used to make external threads.

  30. TECH 104 – Technical Graphics Communication Thread Representation:

  31. TECH 104 – Technical Graphics Communication General Types of Fasteners:

  32. TECH 104 – Technical Graphics Communication The difference between a finished and Unfinished hex head bolt is a washer Under the head of the finished bolt. Finished vs. Unfinished Bolts:

  33. TECH 104 – Technical Graphics Communication Nuts:

  34. TECH 104 – Technical Graphics Communication Cap Screws: Notice the chamfer (Also found on bolts).

  35. TECH 104 – Technical Graphics Communication Machine Screws: Machine Screws are finished with flat bottoms instead of chamfered corners. A ½” Hex Head Machine Screw is used on this week’s assembly drawing.

  36. TECH 104 – Technical Graphics Communication Set Screws:

  37. TECH 104 – Technical Graphics Communication Shoulder Screw: Check Appendix 33 for the dimensions of the shoulder screw required for this week’s assembly drawing

  38. TECH 104 – Technical Graphics Communication Retaining Rings:

  39. TECH 104 – Technical Graphics Communication Lock Washers:

  40. TECH 104 – Technical Graphics Communication Pin Types:

  41. TECH 104 – Technical Graphics Communication Standard Key Types:

  42. TECH 104 – Technical Graphics Communication Rivets:

  43. TECH 104 – Technical Graphics Communication Rivets:

  44. TECH 104 – Technical Graphics Communication Springs:

  45. TECH 104 – TechnicalGraphics Communication This Week’s Drawing Create a complete set of Working Drawings

  46. TECH 104 – Technical Graphics Communication Week 11: Pictorial Drawings

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