1. Technical Drafting –p401
Before a technical object can be manufactured, its shape and dimensions must be determined. A technical drawing must be created.
Technical drawings can be made by hand or on a computer.
To understand these drawings, we must be able to recognize and analyze different projections.
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2. 12.4 Projections
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A projection is the representation of a 3D object on a 2D surface.
Two of the most commonly used projections are:
Isometric
Multiview (a.k.a orthogonal)
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3. A 3D drawing is an isometric projection
A 3D drawing is an isometric projection. The lines representing the length, width, and height make angles of 60° or 120°.
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4. Usually the top, front and right side of the object are illustrated.
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In a multiview projection, each face of the object is drawn separately looking at it from straight on. (not distorted)
Usually the top, front and right side of the object are illustrated.
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5. Write into notes please
12.5 Engineering Drawings
A general arrangement is a technical drawing representing the overall appearance on an object.
It usually includes:
Multiview projection (top, front, & right side)
Isometric projection drawn to scale.
and a title block
Name
Date
Title
Scale
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7. An exploded view separates the parts. uses an isometric projection.
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An exploded view
separates the parts.
uses an isometric projection.
Must give a list of parts.
See p404
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11. 12.6 Detail Drawings:
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specify all of the relevant information for manufacturing a part.
Are usually drawn to scale.
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12. Scale in Drawings 1:1 object is drawn life size
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Scale in Drawings
1:1 object is drawn life size
1:2 reduced scale (drawing of object is ½ of its actual size)
1 cm on drawing is 2 cm on the item.
other ratios include 1:5, 1:10 etc.
2:1 enlarged scale (a small object is drawn larger)
2 cm on drawing represents 1 cm on the item.

13. Short review on lines
On blackboard 

14. Center Lines

18. Start with this one!
FRONT
SIDE
TOP
FRONT
TOP
SIDE

20. 12.7 Accuracy
Since machines, tools, instruments, and the people operating the machines are not perfect, the manufactured parts may be slightly different from the dimensions indicated on the drawing.
A dimensional tolerance is an indicator of the maximum acceptable difference between a specified measurement and the actual measurement on the finished object.
Ex cm
Ex.2
Ex.3
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 From 2.5 to 3.5
 From 12.0 to 12.1
 From 21.8 to 22.1
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21. If the dimensional tolerance applies to all of the parts on a diagram, it may be indicated in the title block.
It can also be applied to a single part and indicated as shown in the diagram.
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22. Write into notes please
The functional dimensioning of a drawing specifies the information required for the object to work.
Eg. How much play is required for a blade to slide freely in a utility knife is shown as the space between the blade and the guide.
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24. 12.8 Developments
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A development is the representation of the surface area required to make a part by bending.
Eg Sheet metal
A dashed line shows where the sheet will be bent.
p407 You need to know the development of a:
Box
Cone
Cylinder
Pyramid
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26. 12.9 Diagrammatic Representations
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12.9 Diagrammatic Representations
Diagram is a simplified representation of an object, a part of an object, or a system.
They are used to help explain an object’s operating principals as well as any other characteristics that must be considered during the manufacturing process.
Depending on the type of information that a drafter wishes to display, one of the following common diagrams will be chosen:
Design Plan
Technical Diagram
Circuit Diagram see page 409
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27. The Most Common Types of Diagrams p408
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28. Design Plan (shows operation)
Name of parts
Movement of parts
Shows forces (constraint symbols are used)
Other…
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29. Symbols for motion Unidirectional translation
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Unidirectional translation
Bidirectional translation
Unidirectional rotation
Bidirectional rotation
Unidirectional helical motion
Bidirectional helical motion

30. Match

31. Technical Diagram (for manufacturing)
Name of parts
Material to be used
Links
Guiding
Other …
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32. Symbols for links & guiding
Complete link
Rotational guiding control
Translational guiding control
Translational & Rotational guiding control
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MORE ON LINKS & GUIDING IN CH13

33. Already covered in Ch 14  Circuit Diagram Shows circuit components
Other….
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Already covered in Ch 14 
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34. Standardized Symbols In Diagrams p 410
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35. Example 1 Choose the link, motion & correct force/constraint. LINK
Example 1 Choose the link, motion & correct force/constraint LINK MOTION FORCE

36. Example 2 Choose the link, motion & correct force/constraint. LINK
Example 2 Choose the link, motion & correct force/constraint LINK MOTION FORCE

37. Example 3 Choose the link, motion & correct force/constraint. LINK
Example 3 Choose the link, motion & correct force/constraint LINK MOTION FORCE

38. Example 4 Choose the link, motion & correct force/constraint. LINK
Example 4 Choose the link, motion & correct force/constraint LINK MOTION FORCE

40. 12.10 Manufacturing: Tools & Techniques
Fill-in handout as we go!
12.10 Manufacturing: Tools & Techniques
Once the materials have been chosen and the plans have been drawn, the object must be manufactured.
Manufacturing is the process of creating a technical object.
The various steps in the manufacturing of an object requires the use of various instruments.
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41. A tool is an instrument to manufacture an object.
A hand tool is powered by human force.
A machine tool is powered by forces other than human.
The manufacturing process is usually divided into three parts:
Measuring & laying out
Machining the parts
Assembling & finishing the parts
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42. Step 1 Measuring & Laying Out
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Step 1 Measuring & Laying Out
Find the needed information from:
the detailed drawing(s), or the
“manufacturing process sheet” has:
the steps needed to make a part, &
a list of the materials & tools required.
1. Measuring out is determining the size/position of a marking.
2. Laying out is tracing markings or reference points onto a material.
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43. Write into notes please
Step 2 Machining
Machining is shaping a material into a desired configuration.
#1 - cut it out roughly.
#2 – precision work.
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44. Cutting = giving a material a desired shape.
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Cutting = giving a material a desired shape.
Drilling = making a hole in a material.
Tapping = a machining technique in which screw threads are formed inside pre-drilled holes.
Threading = a machining technique in which screw threads are formed around a rod.
Bending = a material is curved into a certain shape.
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45. Write into notes please
Step 3 Inspection
The parts are measured and inspected to ensure that they match the required specifications (tolerances).
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46. Step 4 Assembling and Finishing
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Step 4 Assembling and Finishing
Assembling = various parts are united to form a complete technical object.
Techniques used for assembling include:
nailing,
screwing,
bonding,
Riveting,
bolting,
welding.
Finishing The finish protects the materials from the elements and enhances the appearance of the object.
Finishing techniques include:
painting, varnishing, staining, polishing.
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