📐 Lesson 4-6: Parametric Constraints
Add design intelligence by locking geometry with dimensional and geometric rules.
📚 What You’ll Learn
By the end of this lesson, you’ll be able to:
Understand the purpose of parametric constraints
Use geometric constraints to control relationships (e.g., parallel, perpendicular)
Apply dimensional constraints to control size and distances
Create smart geometry that adjusts predictably
Use the Parameters Manager to fine-tune constraints
🧠 Why It Matters
Parametric constraints let you embed design logic directly into your drawings. That means you can change dimensions or relationships and the drawing updates automatically. It’s a key step toward smarter, more adaptable CAD work—especially useful in mechanical design, architecture, or any repetitive layout work.
🛠️ Tools You’ll Use
Tool / Feature Description GEOMCONSTRAINTApply geometric relationships like perpendicular, parallel, tangent DIMCONSTRAINTApply dimensional rules (length, angle, diameter) Parametric Tab Ribbon tab with all constraint tools Parameters Manager View, edit, and control named parameters SHOWCONSTRAINT / DELCONSTRAINTView or remove existing constraints
🧭 Lesson Structure
1️⃣ Introduction to Parametric Design
What are parametric constraints ?
Benefits: Consistency, faster edits, adaptive geometry
Where they are used (mechanical, architectural, etc.)
2️⃣ Geometric Constraints
Overview of tools: Coincident, Horizontal, Vertical, Parallel, Perpendicular, Tangent, Equal
Apply geometric constraints to linework and curvesExamples: Making a rectangle always stay square or circles always tangent to lines
3️⃣ Dimensional Constraints
Use Dimensional Constraints (Linear, Aligned, Angular, Diameter, Radius)
Define variables and assign names (e.g., width = 20)
Use named constraints for reuse and flexibility
4️⃣ Modifying and Managing Constraints
Open the Parameters Manager
Rename parameters and assign formulas (e.g., height = width * 2)
Use the manager to drive changes across the drawing
5️⃣ Best Practices and Cleanup
Use SHOWCONSTRAINT to inspect geometry
Use DELCONSTRAINT or AUTOCONSTRAIN as needed
Keep constraints simple and purposeful to avoid conflicts
✅ Lesson Checklist
Task Completed Applied at least 3 geometric constraints ☐ Used dimensional constraints to lock object sizes ☐ Created a named parameter in the Parameters Manager ☐ Updated a drawing by editing a constraint value ☐ Deleted or modified unnecessary constraints ☐
📌 Quick Tips
Tip Why It Helps Start with clean geometry Prevents conflict when adding constraints Use named dimensions (width, height) Easier to modify and reuse values Combine geometric and dimensional constraints Gives the most stable and flexible control Avoid over-constraining Leads to warnings and unpredictable behavior
🧩 Real-World Applications
Scenario How Constraints Help Machine Parts Holes stay aligned and evenly spaced as size changes Floor Plans Rooms retain proportional dimensions when resized Custom Templates Components remain symmetrical and adaptable Furniture Design Cabinet panels stay connected and scale predictably
📁 Files and Resources
File / Resource Description Parametric Example DWG Sample file with basic constraints and adjustable geometry Parameters Template Predefined variables and formulas for use in drawings Constraints Reference Sheet Quick guide to all geometric and dimensional constraints
📖 Review Table
Constraint Type Function Example Use Geometric Defines how elements relate to each other Keep two lines perpendicular Dimensional Controls length, angle, size Keep circle radius at 10 units Named Parameters Adds formula-driven design logic Set height = width × 2
