1. Constraint Based Modeling
Dimensional Constraints
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Dimensional Constraints

2. Dimensional Constraints
Two different types of constraints:
Geometric
Constraining geometry based on normal orientations or relative to other parts of the geometry
Dimensional
Numerical values that constrain the size and location of geometry
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Dimensional Constraints

3. Dimensional Constraints
Linear Dimensions
Radial Dimensions
Angular Dimensions
Dimensional constraints can be added to linear dimensions such as distance between points or length of segments
Other options include radial dimensions of arcs or circles, and angular dimensions
These constraints should be used in conjunction with geometric constraints in order to create a robust model
Dimensional constraints are not unique and are left up to the designer in how they are applied to create the correct geometry
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Dimensional Constraints

4. Dimensional Constraints
Design Strategy
Effective robust designs starts with shape and geometry constraints, and then dimensional constraints are added
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Dimensional Constraints

5. Dimensional Constraints
Algebraic Constraints
Simple Algebraic Expressions
i.e. 20/3
Related to Other Dimensions
Driving vs. Driven
Is D5 Driving or Driven?
Dimensions can be entered as numerical values or also they can be entered using simple algebraic expressions
Dimensions also can be related to other dimensions already assigned
The primary dimension is referred to as the “Driving” dimension and the related dimension is “Driven”
A “Driven” dimension will also result if the designer tries to over-constraint a geometry that is already determined by other dimensions or constraints
D5 is driven
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Dimensional Constraints

6. SolidWorks: Dimensions
Dimensional Constraints can be added using the Smart Dimension Button
Click on the entity
Move cursor off object
Click once more to place dimension
When Constraints are applied the following dialog box will appear displaying
Dimension Name
Editable Dimension Value
Options (direction, etc.)
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Dimensional Constraints

7. SolidWorks: Dimension Options
Dimensions can be added between 2 lines by selecting the lines sequentially
Between a point and a line
Or even 2 points as long as the correct direction is chosen ( the Smart Dimension tool shows options when moving the mouse)
Caution: Refrain from using point to point unless absolutely necessary. This can cause a variety of problems and is not as robust of a way to apply dimensions.
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Dimensional Constraints

8. SolidWorks: Circles and Arcs
Circles or Arcs can be dimensioned by the diameter (Ø) or radius (R)
A circle can be located by its center point by constraining both the x and y directions
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Dimensional Constraints

9. SolidWorks: Angular Dimensions
Angular Constraints can be added by clicking one line and then the other line. SolidWorks will automatically assume angular constraint.
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Dimensional Constraints

10. SolidWorks: Algebraic Constraints
Constraints can be added in the form of equations by:
Entering “=“
Entering a value or by left clicking on a dimension
Using operations +, -, *, /
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Dimensional Constraints

11. Dimensional Constraints Wrap Up
Linear
Radial
Angular
Coupled with Geometric Constraints
Algebraic
Relations between dimensions
Homework Assignment Problem 6.4 (r)
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Dimensional Constraints

12. Dimensional Constraints
In-Class Assignment
Open the seed file in the course drive. Adjust the shape using geometric constraints and then add dimensional constraints to finalize the model. Print off with name in Sketch mode so the constraints can be viewed
Start with the simple shape and then move on to the harder if time remains. Try to use both geometric constraints and dimensional constraints in order to quickly create the following objects.
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Dimensional Constraints