Chapter 2 Sketching, Constraining & Dimensioning

After completing this chapter, you will be able to do the following: –Change the sketch and part options –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 tool –Change a dimension’s value in a sketch –Import AutoCAD DWG data Chapter 2 - Objectives

Sketch & Part - Application Options Options –Customized your preferences –Settings are global –Affects all open & new Inventor documents

Sketch - Application Options Constraint Placement Priority Display Overconstrained Dimensions 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 3D Sketch

Part - Application Options Sketch on New Part Creation Construction Auto-hide in-line work features Auto-consume Work Features and Surface features

Part - Application Options 3D Grip Dimensional Constraint Relocation 3D Grip Geometric Constraint Relocation

Units –Default unit of measurement –Part, Assembly & Drawing files –Template file –Changing - Overridden –Edit dimension

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 –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

Sketch the Outline of the Part Using the Sketch Tools –Visual feedback 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 Selecting Objects –individually objects –multiple objects –color change Deleting Objects –right-click Delete Sketch the Outline of the Part Automatic Constraints –Constraint symbols Scrubbing –different constraint applied –move the cursor so it touches Selecting Objects –individually objects –multiple objects –color change Deleting Objects –right-click Delete

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

Measure Tools Measure –Distances Points Edges Faces Parts –Angles –Loops –Area –Region Properties

Analysis Tools Measure –Additional Options –Click the arrow in the Measure dialog box ResetClears the contents of the measurement box Add to AccumulateAdds the measurement in the measurement box to the accumulate Clear AccumulateClears all measurements from the accumulate sum Display AccumulateDisplays the sum of all measurements added to the accumulate All DecimalsChanges 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 Fix constrain –Constraint Types 12 geometric constraints

Constraining the Sketch Geometric Constraints –Adding Constraints Applying Over-constrain –Constraint Visibility

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 Standard toolbar 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 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

Adding Dimensions –Dimensioning Arcs and Circles Circumference Arc = radius Circle = diameter –Diametric Dimensions Revolved part Represent a quarter outline Linear diameter 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

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

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

Exercise 2-4 Dimensioning A Sketch

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 SAT STEP PRO/E Parasolids SolidWorks Unigraphics DXF IDF Board File IGES

Exercise 2-5 Inserting an AutoCAD File

Applying Your Skills Skill Exercise 2-1Skill Exercise 2-2

Project Exercise - Chapter 2 Sketching, Constraining, and Dimensioning In Appendix A

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 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_ If you use the Auto Dimension tool on the first sketch in the part, the sketch will be constrained fully. 8.True_ False_ You can import only 2D AutoCAD data into Autodesk Inventor. 9.Explain how to draw an arc while still 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.