Lecture Autodesk inventor Parametric sketching

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 2D features then use a 3D construction operation, such as extrude, revolve, or sweep, to create a 3D model.

Parametric Sketching

Solid primitives not typically supported in parametric modelers  must create a 2D profile, then sweep

Feature Creation Procedure

1. Choose sketch plane, either a:

 Default work plane

 Planar face of existing feature

 Work plane

2. Rough sketch

 Some geometric constraints applied

3. Add/delete geometric constraints

4. Parametric dimensioning

5. Feature creation

6. 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

equal tangent concentric

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 Over-constrained Sketches

Under-constrained Over-constrained

Vertical position of

hole not specified

Angle not necessary

Parametric Sketching