Team-based design and CAD modelling using Lego in first
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Transcript Team-based design and CAD modelling using Lego in first
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ES050 – Introductory Engineering
Design and Innovation Studio
Engineering drawings
Prof. Paul Kurowski
January 13, 2010
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Creating drawings
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Creating drawings
pot.SLDPRT
pot.SLDDRW
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Creating drawings
bracket.SLDPRT
bracket.SLDDRW
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Creating drawings
hanger.SLDPRT
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Creating drawings
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Creating drawings
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Drawings are constructed to strict standards to ensure a consistent
interpretation.
Often are part of a contractual document
Emphasis is on clarity and simplicity.
Generally prefer to use symbols over notes since manufacturer may
not speak English.
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PARTS OF A TYPICAL DETAIL DRAWING
sheet
revision
block
views
title
Block
(TOC)
notes
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DRAWING SHEET SIZES
North America
International
A
8.5”x11”
A4
210mm x 297mm
B
11”x17”
A3
297mm x 420mm
C
17”x22”
A2
420mm x 594mm
D
22”x34”
A1
594mm x 841mm
E
34”x44”
A0
841mm x 1189mm
Choose sheet size such that drawing is filled but not crowded (based on number of
views and dimensions needed).
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DRAWING SCALE
Title block indicates scale which is predominantly used for views on
drawing.
If a view uses a different scale it must be indicated under that view.
Scales are given as whole number ratios
interpret as (drawing unit) : (physical unit)
for scaling up: e.g. 2:1, 4:1, 10:1
for scaling down: e.g. 1:2, 1:5, 1:20
must have a 1 in the ratio. e.g. 2:3 not acceptable
Scale is chosen so that the features can be clearly seen.
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NOTES
Gives useful information not covered by dimensions, symbols or in
the title block.
Can also be used with arrows to indicate features of importance.
Current practice is to limit the use of notes since they may be
misinterpreted.
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DRAWING VIEWS
Only use the number of views necessary to convey information
about the part (an isometric view is the exception)
Often need only two or three views
Edges which are visible in that view are shown as solid lines
Edges which are not visible are called hidden lines
Best not to show hidden lines
you cannot dimension to hidden lines anyway
they reduce clarity in drawings of complex parts
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ORTHOGRAPHIC (PROJECTED) VIEWS
Primary views on a drawing
Set of views at 90° to each other
Created by placing part in a virtual box and look through each side.
True size and shape
angles are correct
circles are round
lengths are to scale
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ORTHOGRAPHIC STANDARD PRACTICE
Choose front view as most descriptive
Determine views to best represent object
Use minimum number of views to completely describe object
Views must be aligned
Views should not be labeled
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AUXILIARY VIEWS
It is an extra view of an object
It is used when the 6 principal views don’t describe an object (or
some of its features) clearly or completely - in particular inclined
features
Should not be labeled
It is used to show the true lengths of lines
It is used to show the true size of planes
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AUXILIARY VIEW
ORTHOGRAPHIC (PROJECTED) VIEWS
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SECTION VIEWS
Useful to show interior features without using hidden lines
Must show section line in another view which indicates the cutting
plane and the direction of view
Does not need to be aligned with parent view but often is shown
aligned to enhance clarity
Must have unique letter label
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SECTION VIEWS
section line
unique view label
cutting plane surface
cross-hatched
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ALLIGNED SECTION VIEWS
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DETAIL VIEWS
Used as enlargement of another view to enhance clarity of small
features
Must show detail area in parent view with label
Is not aligned with parent view
Must have unique letter label and scale must be indicated since it is
different from the parent view
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DETAIL VIEWS
detail
area
with label
detail view with label
and scale
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BREAK VIEWS
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ISOMETRIC VIEW
3D view of part used to help visualization
Common if 3D CAD system used to develop drawing
Used only for a visual reference. Do not dimension this view.
Common now for assembly drawings.
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ISOMETRIC VIEW
Orthographic (projected) views
isometric view
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What type of
view is this?
ES1050 PART 01.sldprt
The view indicated by the callout is:
A
Projected
B
Auxiliary
C
Section
D
Aligned section
E
Detail
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What type of
view is this?
ES1050 PART 01.sldprt
The view indicated by the callout is:
A
Projected
B
Auxiliary
C
Section
D
Aligned section
E
Detail
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What type of
view is this?
flange.sldprt
The view indicated by the callout is
A
Section
B
Aligned section
C
Detail
D
Broken out section
E
Break
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What type of
view is this?
flange.sldprt
The view indicated by the callout is:
A
Projected
B
Auxiliary
C
Section
D
Aligned section
E
Detail
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What type of
view is this?
flange long.sldprt
The view indicated by the callout is
A
Projected
B
Section
C
Detail
D
Broken out section
E
Break
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CENTRE LINES
Used to indicate centres of full circles and axis of cylindrical features
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ASSEMBLY DRAWINGS
Assembly drawings show all the parts and how they go together.
Dimensions are not usually required.
A parts list or Bill of Material (BOM) specifies the item, quantity,
description, part number, etc. for each part.
The item numbers from the parts list for each part are indicated
using numbered balloons in the view.
Common styles used for assembly drawings:
as assembled view
section view
exploded view - Preferred!
Notes are used for assembly and machining instructions
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ASSEMBLY DRAWING AS ASSEMBLED
BOM
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ASSEMBLY DRAWING SECTION VIEW
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ASSEMBLY DRAWING EXPLODED VIEW
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DIMENSIONING OUTLINE
General Rules
Linear Dimensions
Angular Dimensions
Radial Dimensions
Diameter Dimensions
Holes
Tolerances
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INTRODUCTION
Dimensions give size, location and details of all features of the part.
Manufacturing method is not specified but driven by dimensions,
material and tolerances.
Dimensions are used per a standard to ensure consistent
interpretation and clarity
Dimension standard often indicated on drawing in title block.
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GENERAL RULES
Text height for dimensions and notes typically either .12” or 3 mm.
Text is always uppercase.
Units are usually either inches or millimetres.
If using inches:
no zero precedes decimal (.250)
dimensions expressed to same number of decimals as its tolerance
(.250±.002)
If using millimetres:
zero precedes the decimal (0.5)
no trailing zeros are required (2±0.5, 3.25±0.1)
Dimension text is always horizontal.
Do not dimension to hidden lines.
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LINEAR DIMENSIONS
dimension
line
visible gap
extension
line
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DIMENSION PLACEMENT
Dimensions are placed outside the part.
Do not crowd dimensions and avoid crossing dimension lines with
extension lines.
space
space
aligned
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ANGULAR DIMENSIONS
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RADIAL DIMENSIONS
Small radii are called fillets.
Preference is to use unlocated centres (easier to measure)
Unlocated Centre
Located Centre
radius
symbol
leader line
centre
mark
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RADIAL DIMENSIONS
Never dimension to radii tangent points.
Tangent point
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DIAMETER DIMENSIONS
large diameter
diameter
symbol
centreline
small diameters
(arrows don’t fit inside)
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HOLE DIMENSIONS
Multiple holes are common on parts so standardized symbols have
been adopted.
Thru Hole
Blind Drilled Hole
depth
symbol
depth of full
diameter
note drill
point
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COUNTERBORED HOLES
Thru Hole
Blind Hole
counterbore
diameter & depth
counterbore
symbol
Note: depths always
measured from top surface
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DIMENSIONING TECHNIQUES
Must give position and size of each feature but only once on the
drawing.
do not dimension the same feature again in a different view
unless dimension for reference only
Dimension based on the function of the feature.
Dimension to reduce tolerance stack-up for critical features.
Always dimension position of holes to their centre not their edge.
Tolerance scheme in the solid model may not be suitable for the
drawing.
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OVER DIMENSIONED
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REPEATED FEATURES
Repeat symbol
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WHAT IS WRONG?
lever.sldprt
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WHAT IS WRONG?
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WHAT IS WRONG?
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WHAT IS WRONG?
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WHAT IS WRONG?
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WHAT IS WRONG?
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WHAT IS WRONG?
flange.sldprt
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WHAT IS WRONG?
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WHAT IS WRONG?
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