Sketching is an important tool for quickly and efficiently communicating design ideas. It is a particularly useful tool early in the design process when several ideas are being explored. A fundamental technique within most parametric modeling programs is to sketch 2-D features then use a 3-D construction operation, such as extrude, revolve, or sweep, to create a 3-D model.
Parametric Sketching Motivation Solid primitives not typically supported in parametric modelers must create a 2D profile, then sweep Feature Creation Procedure Choose sketch plane, either a: Default work plane Planar face of existing feature Work plane Rough sketch Some geometric constraints applied Add/delete geometric constraints Parametric dimensioning Feature creation Repeat 1 5 Construction Geometry Geometry created as part of the parametric modeling process that does not represent actual part geometry. Includes: Work planes Work axes Work points Construction geometry appears in feature tree Default Construction Geometry: Inventor Work planes – mutually perpendicular YZ XZ XY Work Axes X (red) Y (green) Z (blue) Work Point Origin of WCS Rough Sketch Parametric sketching imitates actual sketching process rough, approximate Sketch Plane Views View normal to sketch plane Isometric View Geometric Constraints Typical constraints include: vertical, horizontal, collinear, concentric, tangent, etc Inventor constraints Display Geometric Constraints Software includes option to show constraints Add/Delete Constraints User can manually (explicitly) add constraints tangent concentric equal Parametric Dimensions Add parametric dimensions to fully constrain profile Each parametric dimension has two components: Numerical value Name Fully Constrained Sketch Parametric Dimensions 2 Default parameter names (e.g., d0) can be changed Equations can be used to generate parameter value Under and Overconstrained Sketches Vertical position of hole not specified Underconstrained Angle not necessary Overconstrained Parametric Sketching ... equal Parametric Dimensions Add parametric dimensions to fully constrain profile Each parametric dimension has two components: Numerical value Name Fully Constrained Sketch Parametric Dimensions 2... X (red) Y (green) Z (blue) Work Point Origin of WCS Rough Sketch Parametric sketching imitates actual sketching process rough, approximate Sketch Plane Views View normal to ... Some geometric constraints applied Add/delete geometric constraints Parametric dimensioning Feature creation Repeat 1 5 Construction Geometry Geometry created as part of the parametric modeling process that does not