Learning Targets
- Apply common geometric constraints.
- Diagnose under-constrained geometry by dragging.
- Use constraints to preserve design intent without relying on Fix/UnFix.
IED Unit 2 • Lesson 2.3
Sketch Constraints
Focus question: How can constraints make a CAD sketch behave the way an engineer intends?
Your lesson guide
Objective
Apply common geometric constraints. Diagnose under-constrained geometry by dragging. Use constraints to preserve design intent without relying on Fix/UnFix.
Materials
For the online work: a browser and your engineering notebook. Follow the activity’s materials list for any physical build, and get teacher approval before using equipment.
Plan your time
Suggested work block: 45–60 minutes. Physical builds and projects may span several classes; follow your teacher’s schedule.
Lesson Overview
What You Are Learning
How to Approach the Work
Use the instructor demonstration to understand the tool or design decision, then complete the assigned work independently and verify the result before submission.
LearnModelVerifyReviseSubmit
Reference Image
Sketch Constraints Practice Sheet
Use this reference while repairing and discussing common sketch-constraint relationships.
This image is a visual guide. If your instructor provides a Fusion practice file, complete the repairs in that editable file.
Assignment
Sketch Constraints
Constraints control how sketch geometry is allowed to move. Your job is to repair sketches using geometric relationships rather than locking geometry in place with Fix/UnFix.
Step-by-Step Instructions
- Test each broken sketch first: Before adding any constraint, click and drag geometry to see how the sketch currently moves. Use the motion to identify what relationship is missing.
- Apply geometric constraints: Use Horizontal/Vertical, Coincident, Parallel, Perpendicular, Tangent, Equal, Concentric, Midpoint, and Symmetry as appropriate. Use the smallest number of constraints needed to communicate the design intent.
- Re-test the sketch: Drag the geometry again after each repair. A correct constraint should stop the unwanted motion while still allowing any intended freedom.
- Avoid unnecessary Fix/UnFix: Do not use Fix/UnFix as a shortcut to make geometry turn black. A sketch is only well constrained when its relationships and dimensions control it for a reason.
- Revise the Lesson 2.2 mounting plate: Open your mounting-plate sketch and add the appropriate geometric relationships. Leave dimensions for Lesson 2.4, so some controlled dimensional freedom should remain.
- Identify remaining degrees of freedom: Determine what can still move or change in the mounting plate and be ready to explain what dimension would eventually control it.
Before You Submit
- Constraints match the intended geometry.
- The sketch does not rely on Fix/UnFix as the primary control method.
- The mounting plate still has intentional dimensional freedom.
Submission
What You Will Submit
File requirements: Export the editable design using File → Export → Fusion 360 Archive Files (*.f3d). Submit the exported .f3d file rather than a link to your Fusion project.
Reference
Video Help
Fusion 360: Sketch Constraints
Use this video if you need to review the skill after the instructor demonstration. Follow the class requirements when the example differs from the assigned work.
Resources
Lesson Resources
IED Unit 2
Return to the Unit 2 lesson list and course sequence.
Introduction to Engineering Design
Return to the IED course hub for units, resources, certifications, and current course information.
Build your lesson report
Checkpoint: is your evidence ready?
- Check calculations, units, labels, and measurements against the activity requirements.
- Record what actually happened, including unexpected results.
- Explain what you changed and why; attach required drawings, photos, CAD, or code in your classroom assignment.
Fusion archive: one design containing the five repaired sketches and revised mounting plate. Export as LastName_FirstName_2_3_Constraints.f3d. Written response: identify one remaining degree of freedom in the mounting plate and explain what information would be needed to remove it. File requirements: Export the editable design using File → Export → Fusion 360 Archive Files (*.f3d). Submit the exported .f3d file rather than a link to your Fusion project.
A PDF download is not a submission. Review it, then upload it and any required attachments through your classroom assignment system.