CAD and Drafting Standards
Working Drawings
Gregory Mocko
2Introduction
The purpose of drawing or generating a CAD document is to communicate
Essentially, since communication is the goal, some standards must be used, otherwise misunderstandings occur.
There are several standards, namely ASME Y14.5 and other US standards and ISO norms. They provide guidelines on how to communicate unambiguously.
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3Overview
Working drawings are what the design is implemented fromA detail drawing is of a single part of detailSpecification are written instructions that go with the drawingsSpecifications may be written on the drawings or on a separate sheetTolerances, mating, contact surfaces, proper motion must be insured – this is completed by designer not drafterThey are legal documents
– Describe what will be made
They must be revised and modified under control ($)
4Basic Elements of Working Drawings
Dimension and units– Remain consistent across all components– Dual dimensions may appear – note not continuous
Layout of drawing– Identify required views– Use scale– Title block
NotesChecking a drawing
– A designer and drafter– Result in a better product
Assembly Drawings– All parts that are made must be fit together
5Title Blocks
Name & Address of companyTitle of DrawingDrawing NumberNames and dates of drafter, checker, issue date,…Approval BlockPredominant Drawing ScaleSheet Number
6Bill of Material
Name of partPart Material# of times the part is usedPart Number (company assigned)Located lower right corner (ANSI)
7Multi-view Working drawing
8Assembly drawing
All parts drawing in their operating positionPart list or Bill of MaterialLeader lines with balloonsMachining and assembly operation specification
9Assembly drawing
10Revision Block
Because design changes/correction occursContains date, names, description, change number and approval
11Scale
Placed in the title blockMore than one scale – then its mentioned near the detailed drawing
12Tolerance Specification
Placed in title blockGeneral tolerance note for dimensions that don’t have specified tolerance
13Working Assembly Drawing
Combined detail drawing and assembly drawingUsually Sectioned viewHave mainly standard/purchased parts
14Working Assembly Drawing
15Alphabet of Lines
Object Lines
Hidden object lines
Center lines, axes
Extension lines, arrows
Cutting planes for sectioned views
16Drawing Rules
Unless absolutely compelled to do otherwise, honor the conventional rules of orthographic projection with top front and side views arranged as shown in the second figure of this presentationUse appropriate line weights (see previous slide)Normally, try dimension cylinders in views where they appear as rectangles. Dimension and locate holes where they appear as circlesAlways indicate centerlines for cylinders and holesAlways locate circles (and cylindrical features) from their centers.Dimension Holes by specifying the DIAMETERDimension rounds by specifying the RADIUS
17Drawing Rules
Make sure tolerances are specified where needed and appropriatelyDo not over define the tolerances, cost will be prohibitiveMake sure someone else can understand your drawing and can produce a 3D rendition from your CAD dataDo not forget to specify materialsWrite who has done the design and is responsible for itPut date of design, file name and location to find it later onNumber pages if multiple pages are needed, put titles and refer to appropriate drawings for clarifications, additional information.
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WORKING DRAWINGS EXAMPLE
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Isometric ViewsFront View
20Exploded Assembly
21Part 1: Forward Arm
22Part 2: Yoke Brace
23Part 3: Support Link
24Part 4: Hex Bolt
25Part 5: Hex Bolt (160mm)
26Part 6: Hex Bolt (260mm)
27Part 7: Hex Bolt (360 mm)
28Layout Drawing
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