Chapter 2
Sketching, Constraining &
Dimensioning
Chapter 2 - Objectives
• After completing this chapter, you will be able to
do the following:
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Change the part and sketch options as needed
Sketch an outline of a part
Create geometric constraints
Use construction geometry to help constrain sketches
Dimension a sketch
Create dimensions using the automatic dimensioning
command
– Change a dimension’s value in a sketch
– Open and insert AutoCAD DWG data
Sketch & Part - Application
Options
• Options
– Customized your preferences
– Settings are global
– Affects all open & new Inventor documents
Part - Application Options
• Sketch on new part creation
• Construction
• Auto-hide in-line work
features
• Auto-consume work
features and surface
features
• 3D grips
• Edit Base Solids Using
Sketch - Application Options
• 2D Sketch
• Display
• Overconstrained dimensions
• Spline fit method
• Heads-Up Display
• Snap to Grid
• Edit dimensions when created
• Autoproject edges during curve creation
• Autoproject edges for sketch creation and edit
• Autoproject part origin on sketch create
• Point alignment
• 3D Sketch
Units
• Units
– Default unit of
measurement
– Part, Assembly &
Drawing files
– Template file
– Changing Overridden
– Edit dimension
Templates
• Templates
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New files created from a template
Add or Modify templates
Template directory
Subdirectory
• New Tab
Creating a Part
• From the Open dialog box click the Standard.ipt
icon in the Open dialog box
• From the New file drop list on the Standard
toolbar
Creating a Part
• Sketches & Default Planes
– Sketch plane
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2D objects are sketched
Active sketch
Three planes
XY,YZ, and XZ
Three Axes
– X, Y, and Z
• Center
– Origin - point at the intersection
• Browser
• New Sketch
– Create 2D Sketch
– Active sketch
Sketch the Outline of the Part
• Step 1 - Sketches Overview
– Sketching strategies, tools, & techniques
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Outline
Draw to finished size/shape
Visual Guide – distance & angle
No overlaps & gaps
Keep shape simple
Closed vs. Open shape
– Sketch Tools
• Sketching tools
• Expert mode on/off
Dynamic Input
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Polar or Cartesian Coordinates
Persistent Dimensions
Heads-Up Display Settings
Dimension Input
Sketch the Outline of the Part
• Using the Sketch Tools
– Visual feedback
– Dynamic Input
• Line Tool
– Powerful tool
– Endpoint - Arc
• Object Tracking - Inferred Points
– Dashed lines
– Endpoints
• horizontal
• vertical
• perpendicular
Sketch the Outline of the Part
• Automatic Constraints
–Constraint symbols
• Scrubbing
–different constraint applied
–move the cursor so it touches
Constraint Persistence & Inference
• Persistence
– Turns sketch constraints on/off
– When on, sketch constraints are applied while sketching
– When off, the constraint icon will appear on the screen,
but it will not be applied to the sketch
• Inference
– Turns the preview of the constraint on/off
– When off, Constraint Persistence is also turned off
– When off, sketch constraints are not applied
Constraint Options
• With Constraint Inference on you can
control which sketch constraints can be
inferred and which geometry they should
be inferred from
Select Objects
• Selecting Objects
–individually objects
–multiple objects
–color change
• Deleting Objects
–right-click Delete
• Measure
Measure Tools
– Distances
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Points
Edges
Faces
Parts
– Angles
– Loops
– Area
– Region Properties
Measure Tools
• Measure
– Additional Options
– Click the arrow in the
Measure dialog box
Reset
Clears the contents of the measurement box
Add to Accumulate
Adds the measurement in the measurement box to the accumulate
Clear Accumulate
Clears all measurements from the accumulate sum
Display Accumulate
Displays the sum of all measurements added to the accumulate
All Decimals
Changes the decimal display between all decimals and the number
of decimal places specified in the document settings
Exercise 2-1
• Creating A Sketch with Lines
Exercise 2-2
• Creating a Sketch with Tangencies
Constraining the Sketch
• Step 2 - Geometric
Constraints
– Apply behavior
– Create relationships
• Status Bar
• Fully constrain
• Use projected origin point
– Constraint Types
• 12 geometric constraints
Constraining the Sketch
• Geometric Constraints
– Dragging a Sketch
• Constrained or Not
• Geometry stretches
– Showing Constraints
• Show all & Hide all F8 and F9
• To see applied constraints
• Objects change color
– Deleting Constraints
• Right-click or Delete key
Construction Geometry
• Sketch tab > Format panel
• Add dimensions and
constraints
• Not visible when a feature
is created
• Always available in the
sketch
Sketch Degrees of Freedom
• To see the open degrees of freedom in a
sketch
– Right-click and click Show All Degrees of Freedom
Exercise 2-3
• Adding and Displaying Constraints
Adding Dimensions Manually
• Step 3 – Adding Dimensions
– All dimensions created are parametric
– Control & change size of geometry
– General Dimensioning
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Create linear, angle, radial, or diameter
Automatically snap
Extension lines
Preview image
– Dimensioning Lines
• Endpoints - two
• Length
– Dimensioning an Angle
• Two lines
• Arc
Adding Dimensions
–Dimensioning Arcs and Circles
• Default: Arc = radius
• Default: Circle = diameter
–Linear Diameter Dimensions
• Revolved part
• Represent a quarter outline
• Axis of rotation
–Dimensioning to a Tangency
• Arc or circle
• Constraint symbol changes
• Two quadrants
Adding Dimensions
• Entering and Editing a Dimension’s Value
– Automatically appear
– Change the value
– Edit Dimension option
– Default value
– To change double-click
– Enter exact value
– Accurate to six decimal places
– Smallest dimensions first
– Fractions
Adding Dimensions
•Entering and Editing a Dimension’s Value
–Repositioning a Dimension
• New location
• Origin points cannot be moved
–Over-Constrained Sketches
• Inventor will not allow
– over-constrain
– duplicate constraints
– conflict with another constraint
–Driven dimension
• Reference dimension
• Parentheses
• Over-constrained dimensions option
Adding Dimensions
•Auto Dimension
–Automatically apply
• Dimensions
• Constraints
–State number of dimensions or constraints
required to fully constrain the sketch
–First apply critical constraints and dimensions
–Will not override or replace existing constraints or
dimensions
Exercise 2-4
• Dimensioning a Sketch
Move and Scale Tools
• Move sketch objects to another location
– Move or make copy
• Scale a sketch
– Enter scale factor
– Pick two points
– Relax dimensions
– Relax constraints
Opening/Importing AutoCAD Files
• Copy to clipboard within Inventor
or AutoCAD and Paste in
Inventor
• Open/Import AutoCAD &
AutoCAD Mechanical Files
– New Drawing
– New Part
– Title Block
– Border
– Symbol
– 2D and 3D
• Import 2D geometry to an active
sketch (part or drawing)
Importing Other File Types
• DXF
• Alias
• IDF Board File
• IGES
• JT
• Parasolids Binary Files
• Parasolids Text Files
• PRO/Engineer Files
• SAT
• STEP
• SolidWorks Files
• UGS NX Files
Exercise 2-5
• Inserting AutoCAD Data
Applying Your Skills
• Skill Exercise 2-1
Skill Exercise 2-2
Checking Your Skills
1. True__ False__ When you sketch, constraints are not applied to the sketch by
default.
2. True__ False__ When you sketch and a point is inferred, a constraint is applied to
represent that relationship.
3. True__ False__ A sketch does not need to be fully constrained.
4. True__ False__ When working on an mm part, you cannot use English (inch)
units.
5. True__ False__ After a sketch is constrained fully, you cannot change a
dimension’s value.
6. True__ False__ A driven dimension is another name for a parametric dimension.
7. True__ False__ Dimensions placed dynamically are not parametric.
8. True__ False__ You can import only 2D AutoCAD data into Autodesk Inventor.
9. Explain how to draw an arc while in the Line command.
10. Explain how to remove a geometric constraint from a sketch.
11. Explain how to change a vertical dimension to an aligned dimension while you
create it.
12. Explain how to create a dimension between two quadrants of two arcs.