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Working Drawings
Chapter 12
2Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Objectives
• Define top down, bottom up, and middle out design
• Discuss methods of constraining assemblies made using solid modeling and parametric modeling
• Identify the elements of a detail drawing
• List the parts of an assembly drawing
3Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Objectives (cont.)
• List six types of assembly drawings• List the role of the record strip and
title block in the approval process• Describe the process for revising
drawings• Describe the special requirements
of a patent drawing
4Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Top Down Vs. Bottom Up Design• Top down refers to starting the
process of design by:• Considering the function of the entire
system• Breaking it down into subassemblies or
components based on major functions• Each part is manufactured and
assembled
5Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Top Down Vs. Bottom Up Design• Bottom up design is helpful when
the components are standardized parts:• The design process starts at the part
level• Individual components are sized and
designed• Final assembly is built around the
design of the parts
6Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Top Down Vs. Bottom Up Design• Middle out refers to a combination
of top down and bottom up design:• Some parts are standardized• Other parts are designed within the
context of fitting into the design of the assembly
7Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Constraining 3D Assemblies• With constraint based modeling
software, assembly constraints create relationships between modeled parts
• The first part added to the assembly becomes the parent part• Other parts are mated to the parent
part to build up the assembly
8Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Constraining 3D Assemblies
9Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Constraining 3D Assemblies• Subassemblies are groups of
components of a larger machine• Breaking products into
subassemblies can make it easier to coordinate when different designers are working on portions of the same device
10Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
3D Layouts and Skeleton Assemblies• An assembly layout or skeleton
assembly can be used to define locations of individual parts in an assembly• Parts are designed so they link to a
skeleton framework in the assembly• The skeleton is a 3D drawing that
defines major relationships in the assembly
11Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Working Drawings or Construction Drawings• Working drawings are a set of
assembly and detail drawing• These drawings are given to
contractors to perform work or manufacture individual parts
• These drawings are legal documents
12Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Assembly Drawings
• Different type of assembly drawings include:• Design assemblies, or layouts• General assemblies• Detail assemblies• Working drawing assemblies• Outline or installation assemblies• Inseparable assemblies (weldments,
etc.)
13Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Assembly Drawings
• Views should show how the parts fit together and suggest function of the unit
• Hidden lines are typically not needed
• Assembly drawings are usually not dimensioned
14Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Detail Drawings
• Detail drawings contain all of the necessary information to manufacture a part
• Detail drawings are also called:• Piece part drawings• Part drawings
15Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Identification
16Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Multidetail Drawings
• When multiple detail drawings are shown on one sheet, identify each part• Place the circles containing the part
numbers adjacent to the parts
17Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Parts Lists
• A parts list or bill of materials (BOM) typically contains:• Part identification number (PIN)• Description of each part• Quantity required in the assembly
• Abbreviations can be used to indicate quantities that are not known such as AR (as required) and EST (estimated quantity)
18Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Parts List
19Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Assembly Sections
• In assembly sections it is necessary to show cut surfaces and distinguish between adjacent parts• To accomplish this, section lines are
drawn in opposing directions• In relatively thin parts, section lines
should be left out or shown solid black• Bolts, nuts, keys, etc. are left
unsectioned
20Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Assembly Sections
21Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Working Drawing Formats
• Number of details per sheet:• Showing one detailed part per sheet
is typically preferred• Machines or structures composed of
few parts sometimes show all the details on one large sheet
22Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Working Drawing Formats
• Electronic file formats such as Portable Document Format (PDF) allow the originator to send a document that can be commented on without allowing the original document to be changed
• Using electronic files also saves trees and makes distribution quicker
23Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Working Drawing Formats
• Title and record strips show all necessary information not given directly on the drawing with its dimensions and notes
• The type of title used depends on the filing system, manufacturing processes, and requirements of the product
24Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Working Drawing Formats
• The title form typically includes:• Name of the object shown• Name and address of manufacturer• Name and address of purchasing
company• Signature of person who made the
drawing and date of completion• Signature of the checker and date of
completion
25Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Working Drawing Formats
• Title form information (cont.)• Signature of the chief drafter, chief
engineer, or other official, and the date of approval
• Scale of the drawing• Number of the drawing
26Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Checking Drawings
• The final checker should review the drawing with particular attention to:• Soundness of design• Choice of views• Dimensions• Standard parts• Notes• Clearances• Title form information
27Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Drawing Revisions
• An accurate record of changes made to released drawings is tracked via a revision block
• The record of revisions should show:• What change was made• By whom the change was made• When the change was made• Why the change was made
28Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Simplifying Drawings
• To simplify drawings:• Use word descriptions when practical• Do not show unnecessary views• Use standard symbols and
abbreviations• Avoid elaborate, pictorial, or
repetitive details• List rather than draw standard parts
29Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Simplifying Drawings
• Cont.• Omit unnecessary hidden lines• Use outline section lining in large areas• Omit unnecessary duplication of notes
and lettering• Use symbolic representation for piping
and thread• Use CAD libraries and standard parts
when feasible
30Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart
© 2009 Pearson Education, Upper Saddle River, NJ 07458.
All Rights Reserved.
Patent Drawings
• Patent applications must include line drawings
• All patent drawings must be mechanically correct and constitute complete illustrations of every feature of the invention claimed
• The U.S. Patent office has strict requirements for patent drawings