fundamentals of engineering – honors – engr h191 lecture 16 - autocad1 question of the day who...
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Lecture 16 - AutoCAD 1
Fundamentals of Engineering – Honors – ENGR H191
Question of the Day
Who created the first practical light bulb?
ANSWER: Joseph Swan, an Englishman,
created the first practical light bulb in 1878
Thomas Edison perfected and marketed the design a year later
Lecture 16 - AutoCAD 2
Fundamentals of Engineering – Honors – ENGR H191
Dimensioning
GoalsUnderstand the principles of good dimensioning practiceApply the standard dimensioning practices for engineering drawings
ReferenceBTG Chapter 7
– Dimensions and Tolerances
Lecture 16 - AutoCAD 3
Fundamentals of Engineering – Honors – ENGR H191
Geometrics
The science of specifying and tolerancing shapes and locations of features of on objects
Lecture 16 - AutoCAD 4
Fundamentals of Engineering – Honors – ENGR H191
Geometrics
It is important that all persons reading a drawing interpret it exactly the same way.Parts are dimensioned based on two criteria: Basic size and locations of the features Details of construction for
manufacturingStandards from ANSI (American National Standards Institute)
Lecture 16 - AutoCAD 5
Fundamentals of Engineering – Honors – ENGR H191
Scaling vs. Dimensioning
Drawings can be a different scales, but dimensions are ALWAYS at full scale.
Lecture 16 - AutoCAD 6
Fundamentals of Engineering – Honors – ENGR H191
Units of Measure
Length English - Inches, unless
otherwise stated Up to 72 inches – feet
and inches over SI – millimeter, mm
Angle degrees, minutes,
seconds
Angle Dimensions
Lecture 16 - AutoCAD 8
Fundamentals of Engineering – Honors – ENGR H191
(.25 in)
(.375 in)
Dimensioning Standards
Lecture 16 - AutoCAD 9
Fundamentals of Engineering – Honors – ENGR H191Dimensioning Basic Shapes -Assumptions
Perpendicularity Assume lines that
appear perpendicular to be 90° unless otherwise noted
Symmetry If a part appears
symmetrical – it is(unless it is dimensioned otherwise)
Holes in the center of a cylindrical object are automatically located
Lecture 16 - AutoCAD 10
Fundamentals of Engineering – Honors – ENGR H191
Dimensioning Basic Shapes
Rectangular Prism
Lecture 16 - AutoCAD 11
Fundamentals of Engineering – Honors – ENGR H191
Cylinders Positive
Negative
Dimensioning Basic Shapes
Lecture 16 - AutoCAD 12
Fundamentals of Engineering – Honors – ENGR H191
Dimensioning Basic Shapes
Cone Frustum
Lecture 16 - AutoCAD 13
Fundamentals of Engineering – Honors – ENGR H191
Dimensioning Basic Shapes
Circle Pattern Center Lines
Lecture 16 - AutoCAD 14
Fundamentals of Engineering – Honors – ENGR H191
Dimensioning Shows:
Size Location & Orientation
Lecture 16 - AutoCAD 15
Fundamentals of Engineering – Honors – ENGR H191
Example Problem
Think Individually, then share with the person next to you.- Compare with the other pair at your table
What dimensions (size & location) are needed?Where should they be placed?
Lecture 16 - AutoCAD 16
Fundamentals of Engineering – Honors – ENGR H191
Grouping Dimensions
Yes No
Dimensions should always be placed outside the part
Lecture 16 - AutoCAD 17
Fundamentals of Engineering – Honors – ENGR H191
Staggering Dimensions
Put the lesser dimensions closer to the part.Try to reference dimensions from one surface This will depend
on the part and how the tolerances are based.
Lecture 16 - AutoCAD 19
Fundamentals of Engineering – Honors – ENGR H191
Repetitive Features
Use the Symbol ‘x’ to Dimension
Repetitive Features
Lecture 16 - AutoCAD 20
Fundamentals of Engineering – Honors – ENGR H191Symbols for Drilling Operations
Lecture 16 - AutoCAD 21
Fundamentals of Engineering – Honors – ENGR H191
Example Problem
What dimensions (size & location) are needed?Where should they be placed?
Think Individually, then share with the person next to you.- Compare with the other pair at your table
Lecture 16 - AutoCAD 22
Fundamentals of Engineering – Honors – ENGR H191
AssignmentsDwg 31 – DIM-1 Fully dimension the objects shown using correct
dimensioning practices.(part is fully dimensioned if it is possible to machine it from the dimensions provided)
Use Inch Dimensions to the second place (x.xx)
Dwg 32 – DIM-2 Fully dimension the objects shown using correct
dimensioning practices. Use one-place metric dimensions (x.x)
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