1. Design Intent: Effectively using Constraints in SolidWorks
Lecture 9, Part 2
IAT 106 Spatial Thinking and Communicating

2. Examples
16:9

3. Objectives Introduce concept of design intent
Use constraints in SolidWorks to match design intent

4. Design Intent What you intend a design to do.
Some intentions can be modeled.
Others not.

5. Modelable Design Intent
I intend that the Centre of Effort align with the Centre of Lateral Resistance.

6. Un-modelable Design Intent
I intend that a new boat design transforms the sport of sailing.

7. A Square? And meet at right angles What is a square?
Square in SolidWorks
Draw rectangle
[Select one edge and define length using Smart Dimension]
Select perpendicular edge, set relationship with previous edge as ‘equal’
Result: square!
A rectangle where sides and diagonals meet at right angles; or
All sides have equal size
|AB| = |BC| = |CD| = |DA|
And meet at right angles

8. Constraint Example model for demonstrating constraints
Constraint refers to the degree of logical or mathematical dependence between or among variables.
In modeling we define geometry of objects, particularly:
Size
Location
Orientation
Example model for demonstrating constraints

9. Constraints in Parts
Often think of constraints when creating assemblies
But, constraints are just as useful when creating parts

10. Types of Constraints Size Location Orientation
Explicit defined by user
AD = AB R = AB / 4
Center point on midpoint of diagonal
Angle DAB and ABC = 90°
Implicit selected by user
Equal
Concentric
Parallel

11. Implicit Constraints Endpoint / Line Overlap Tangency Closure
Segment Overlap
Concentric
Same Size
Perpendicular
Parallelism
Coincident

12. Creating Constrained Model
A: Create rough sketch
B: Define parameters and constraints on dimensions
C: Edit parameters to adjust geometry
D: Generate part using extrusion!

13. Demo
Let’s make a ‘cube’ with a hole through it!

14. Setup to Sketch a Rectangle
Select ‘Sketch’
Select ‘Top Plane’ to draw rectangle

15. Draw Rectangle Draw rectangle ‘roughly’ that looks like a ‘square’
But notice that it is not a square yet
What we need to do to make it square?

16. Set ‘Equal’ Constraint on Edges
Select lower-horizontal edge and select right-vertical edge (holding ‘Shift’ key’)
Select ‘Equal’ from ‘Add Relations’ tools
Notice selected items listed
Notice “ = “ placed next to the lines selected

17. Set ‘Dimension’ Constraint
Select ‘Smart Dimension’
Select lower horizontal edge
A dimension will appear with a dialog box with an input field
Drop down to see options
Select ‘Link Value…’
In the ‘Shared Values’ dialog box, type ‘SIZE’ in the name field; and press OK
We created our first parameter!

18. Parameter Value Changed
Try changing the value on smart dimension; Let’s make it ‘0.05’
What do you expect?
Exit ‘Sketch’

19. Use Parameter Defined
Let’s use ‘SIZE’ parameter to define the height of the CUBE!
Select ‘Sketch’ again
Select ‘Front Plane’ from the ‘Part3’ after collapsing the tree

20. Create Element to Constraint to Parameter
Select ‘Trimetric’ view
Select ‘Center Line’ from ‘Sketch’ toolbar
Draw a construction line from one of the points on the square
“CONSTRAINT” line VERTICAL
Now, let’s define its size… or set it to ‘SIZE’ parameter

21. Set Dimension Parameter
Select ‘Smart Dimension’ one more time
Select the ‘Center Line’ created
Place the dimension element
Select ‘Link Value’ while editing
On the ‘Share Values’ dialog box, select Name pull-down menu to select “SIZE” parameter
Voila! If you change the size of any line reading its value from “SIZE” all others will follow this change!
Advantages?

22. Create the “CUBE”
Select “Extruded Boss/Base” command from “Features” toolbar
Select one of the edges on the square to define the plane
In ‘Extrude’ properties dialog:
Set ‘From’ as ‘Sketch Plane’
Set ‘Direction 1’ to ‘Up To Vertex’
On the drawing, select the top point on the center line (purple)
Confirm all actions by selecting green ‘Check’ buttons!
There you go, this is our parametric cube

23. Challenge
How can we create holes as shown in the figures?

24. Equations and Link Values
Pros
Cons
Equations
Easy to use
Limited set of functions
Without good dimension names, can be difficult to set up
Can't change the driving (left-side) dimension
Link (Shared) Values
Ties a single value together
Any linked valued can be changed, and the other updates
Can provide a direct link only to another value
Hard to understand what's been linked
Limited scope

25. Assignments Reading Text: Chapter 4 “Modeling Fundamentals” Wikipedia:
Solid modeling:
Constructive Solid Geometry (CSG):
Pre-Lab (see next slide , and Pre-Lab document)
Reflective Blog/journal on parts modeling:
Complete after finishing week 9 project deliverables
2 questions on webct

26. This Week’s Lab Step 2 of project Don’t jump into SolidWorks too soon!
Create parts in SolidWorks
Sketch needed parts
Dimension them
Assign parts to group members
Don’t jump into SolidWorks too soon!
Spending more time preparing and planning will save you time in the long run!

27. Pre-lab Assignment Sketch 2 parts from your AMT (nothing too simple)
Dimension
Label constraints
Label relationships
Provide rough plan (sequence of sketches or brief description) outlining approximate steps to create parts in SolidWorks.
See e.g. Feature-Planning Strategies (slide 31 in part 1 slides)