Parametric Mechanical CAD with FreeCAD

Parametric Mechanical CAD with FreeCAD teaches parametric mechanical CAD by designing complete, functional mechanical mechanisms that appear repeatedly in real engineering machines.

Rather than learning FreeCAD tools in isolation, each lesson is built around one fundamental mechanical mechanism, taken from real-world engineering practice. The CAD skills, theory, and workflow required to design that mechanism are introduced within the same lesson, with no assumed prior experience.

Lesson Structure & Approach

Each lesson follows a mechanism-first pedagogical approach:

1. 🔧 Engineering Context Begin with the real-world mechanism and understand why it matters in engineering practice.

2. 📚 Mechanical Theory Learn the fundamental principles of how the mechanism works—kinematics, motion relationships, and key parameters.

3. 🎯 CAD Implementation Apply FreeCAD tools step-by-step to model the mechanism parametrically from scratch.

4. 🛠️ Assembly & Documentation Create proper assemblies with motion constraints and generate technical drawings suitable for manufacturing.

Learning Path

1. Master FreeCAD Fundamentals Learn sketching, constraints, and Part Design workflow through practical mechanism design.

2. Build Parametric Thinking Develop the habit of thinking in terms of design intent, constraints, and parametric control.

3. Create Reusable Designs Build a library of mechanisms that change correctly when parameters are modified.

4. Apply Engineering Practice Use assemblies, technical drawings, and documentation as done in professional engineering.

Course Structure

Every Lesson Includes

Lessons

1. Slider Crank Mechanism The most common motion-conversion mechanism, used in engines, compressors, and pumps. Learn FreeCAD interface, sketching, constraints, part design, parameter tables, basic assemblies, and technical drawings.

2. Four-Bar Linkage Mechanism Fundamental to hinges, folding systems, and mechanical linkages. Master construction geometry, master-sketch driven design, spreadsheet parameter control, and pin-jointed assemblies.

3. Scissor Lift Mechanism Used in lifts, adjustable platforms, and deployable structures. Build repeating parametric geometry, manage symmetry, control stage count via parameters, and understand motion amplification.

4. Toggle Clamp Mechanism Widely used in manufacturing fixtures for locking and force amplification. Design with angle-based constraints, clearance-aware geometry, motion limits, and over-center locking behavior.

5. Pantograph Mechanism Scales motion in copying and tracing mechanisms. Implement ratio-driven parameter relationships, similar triangle geometry, and expression-linked dimensions across assemblies.

6. Cam and Follower Mechanism Fundamental to timed motion in engines and automated machinery. Master curve-based sketching, datum axes, parametric cam profile control, and motion-defining geometry documentation.

7. Geneva Mechanism Provides precise intermittent motion and indexing. Design with polar geometry, pattern-based features, angular constraints, and locking geometry for intermittent motion control.

8. Scotch Yoke Mechanism Offers compact rotation-to-linear conversion with pure sinusoidal characteristics. Create slot-driven motion geometry, clearance considerations, and stroke-based parameterization.

9. Python Scripting for Advanced CAD Unlock FreeCAD’s computational power with Python scripting. Generate mathematically-perfect gears, create lattice structures, automate design optimization, and perform batch operations impossible with GUI alone. Learn algorithmic design for research and advanced engineering.

Pedagogical Philosophy

🎯 Core Principles

• Mechanism-first, tool-second: Learn CAD by doing real design
• Complete designs, not partial exercises: Every lesson produces a functional mechanism
• Parametric thinking from the start: Build models that change correctly
• Engineering intent over visual appearance: Focus on function and correctness
• Reusable designs over one-off models: Create a library of mechanisms you can use

Each lesson can be taken independently, yet together they form a coherent progression from simpler geometry and motion to more complex kinematic behavior.

By the end of the course, learners will not just know how to use FreeCAD. They will have designed a library of reusable mechanical elements and developed the habit of thinking in terms of design intent, constraints, and parametric control.

This mirrors real engineering practice, where CAD is not about drawing shapes, but about building systems that change correctly.

Why FreeCAD Over Alternatives?

This course uses FreeCAD instead of commercial CAD (Fusion 360, SolidWorks, Inventor) or free 3D software (Blender) for evidence-based reasons:

✅ Parametric Engineering CAD, Not Mesh Modeling

FreeCAD: True parametric constraint-based CAD for mechanical engineering

• Designs defined by dimensions, constraints, and relationships
• Change one parameter → entire design updates correctly
• Engineering intent preserved (e.g., “holes always concentric,” “wall thickness constant”)

Blender: Free but mesh-based modeling for animation/visual effects

• Not parametric—moving vertices manually
• No constraint solver or dimensional control
• Excellent for art/rendering, wrong tool for mechanical engineering

Commercial CAD (SolidWorks, Fusion 360): Parametric, but costly and restrictive (see below)

✅ Freedom & Accessibility

✅ Engineering Capabilities

• Parametric Part Design: Sketch-based features with constraint solver
• Assembly Modeling: Multi-part assemblies with motion constraints
• Technical Drawings: Engineering drawings with dimensions, tolerances, annotations
• FEM Analysis: Built-in finite element analysis (CalculiX integration)
• CAM Manufacturing: Toolpath generation for CNC machining
• STEP/IGES/STL Export: Industry-standard formats for collaboration

Educational advantages:

• ✅ Students use it after graduation (no license expiration)
• ✅ Works in startups and low-income regions without budget barriers
• ✅ No vendor lock-in (Autodesk discontinued 123D Design, Inventor LT, AutoCAD)
• ✅ Open-source transparency; inspect algorithms, contribute features, community-driven development
• ✅ Privacy; no telemetry, forced account creation, or data collection
• ✅ Offline capability; works without internet connection

⚠️ Honest Limitations

FreeCAD is actively developed but less mature than decades-old commercial CAD (SolidWorks since 1995, Inventor since 1999). Some manufacturers’ workflows and machines integrate better with commercial CAD file formats and ecosystems. However: FreeCAD’s STEP/IGES/STL export and standard engineering drawings are sufficient for manufacturing most designs you’ll ever build, provided you understand manufacturers’ engineering requirements and communicate tolerances, materials, and processes clearly. The limitation is rarely the software, but understanding manufacturing constraints.

This course teaches engineering CAD methodology and manufacturing-aware design, not necessarily vendor-specific buttons.

Software Requirements

FreeCAD 0.21 or later

Download: www.freecad.org

• Free and open-source
• Cross-platform (Windows, Mac, Linux)
• Professional-grade parametric 3D CAD

Note: The FreeCAD ecosystem includes commercially-backed development efforts such as Ondsel, which contributed improvements (topology naming fixes, UI enhancements) back to the FreeCAD core. This demonstrates both community and commercial interest in advancing the platform.

Prerequisites

No prior CAD experience required

Recommended background:

• Basic understanding of engineering drawings
• Familiarity with 3D concepts
• Interest in mechanical design

What you’ll gain:

• Professional CAD modeling skills
• Parametric design methodology
• Engineering mechanism knowledge
• Technical documentation abilities

Getting Started

1. Install FreeCAD from the official website
2. Start with Lesson 1 (Slider Crank Mechanism)
3. Work through lessons sequentially for best results
4. Practice modifying parameters to understand parametric control
5. Build your mechanism library as you progress