Chapter 2Sketching, Constraining &

Dimensioning

• After completing this chapter, you will be able to do the following:– 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

Chapter 2 - Objectives

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

– 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 • 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• 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• 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

•Automatic Constraints–Constraint symbols

•Scrubbing–different constraint applied–move the cursor so it touches

Sketch the Outline of the Part

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

•Selecting Objects–individually objects–multiple objects–color change

•Deleting Objects–right-click Delete

Select Objects

Measure Tools • Measure

– Distances• 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

• Creating a Sketch with Tangencies

Exercise 2-2

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

• 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

•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

Adding 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 Skills1. 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.