【Mechanical Design】🛠️ 02. What Is FreeCAD? — A CAD Tool for Describing Design as Code

topics: [“cad”, “freecad”, “mechanical design”, “python”, “design philosophy”]

🧩 What Is FreeCAD?

— A CAD Tool for Describing Design as Code

Going one step beyond GUI-based CAD,
there is an approach in which design is written and reused as code.

If you want to actually try this way of thinking,
the next question becomes:

Which CAD tool should you use?

In this article, we introduce FreeCAD
as one concrete answer to that question.

🎯 Why FreeCAD?

FreeCAD is not chosen simply because it is “free.”

The essential reasons are the following:

• Python is integrated as a first-class language
• GUI operations can be recorded and reproduced as Python code
• Parametric design is assumed from the beginning
• The internal structure is relatively open and traceable

In other words, FreeCAD is:

Not a CAD for drawing shapes,
but a CAD for describing the rules that generate shapes

🔁 The Relationship Between GUI Operations and Code

In FreeCAD, many GUI operations can be replayed as
Python macros.

This is a critical feature for code-based design.

• GUI operations: shapes are created, but reasoning is hard to preserve
• Python code: design conditions and intent remain explicit

You can naturally follow the workflow:

1. Create geometry via GUI
2. Convert it into code
3. Reuse and generalize it as design logic

🧪 Example: Geometry Generated Purely from Python Code

Below is an example of a model generated in FreeCAD
entirely from Python code.

This model has the following characteristics:

• It is not the result of manual GUI drawing
• It is the execution result of parameters and design rules
• Changing numerical values produces different shapes under the same rules

What matters is not what shape it is,
but that the reason for the shape is preserved in code.

🏭 Relationship with Commercial CAD

FreeCAD does not reject commercial CAD tools.

In practice, the following division of roles works well:

• Design exploration, shape generation, trial and error: FreeCAD + Python
• Production drawings, tolerances, final deliverables: commercial CAD

FreeCAD is not a replacement,
but a tool that changes the upstream part of the design process.

🔧 What Actually Changes

By using FreeCAD:

• Design conditions can be managed as code
• Dimension changes become “re-execution,” not manual operations
• Designs become easier to reuse and derive

This is not just a tool change,
but a shift in how design itself is held and understood.

📝 Summary

• FreeCAD is highly compatible with code-based design
• Python can naturally be used as a design language
• GUI operations and code are directly connected
• Design can be treated as a reusable asset

FreeCAD is not universal, but
it is an excellent CAD for experimenting with the idea of design as code.

📎 Notes

This article introduces FreeCAD as prerequisite knowledge
for understanding code-based mechanical design.

For licensing and concrete usage conditions,
please refer to the official documentation and website.

This article does not recommend or restrict
any specific product or license.