Getting Started with CATIA: From a 2D Sketch to a 3D Part

If you're a mechanical engineering student, CATIA can look complicated when you first open it.

There are workbenches, toolbars, specifications trees and plenty of modelling tools.

You might wonder:

“Which tool should I start with?”

The easiest way to understand CATIA is not by trying to learn every command.

Instead, start with one simple part and understand how a design develops from a 2D sketch into a 3D model.

In this tutorial, we'll create a simple L-shaped mounting bracket.

Step 1: Open CATIA and Start Part Design

Open CATIA and select:

Start → Mechanical Design → Part Design

Create a new part.

Give it a simple name such as:

Mounting_Bracket

You will see the Specification Tree on the left.

The tree is important because it shows how your model has been created step by step.

For example:

Part → Body → Sketch → Pad → Pocket

Think of it as the history of your design.

Step 2: Create Your First Sketch

Select the XY Plane.

Click:

Sketcher

You are now working in a 2D environment.

This is where we'll create the basic profile of our bracket.

Select the Profile/Rectangle tool and draw a rectangle.

For this tutorial, let's use approximately:

100 mm × 60 mm

Don't worry about getting the size perfect while drawing.

We'll define the dimensions using constraints.

Step 3: Add Constraints

This is where CATIA's parametric design approach becomes useful.

Use the Constraint tool to define the dimensions.

Set:

• Length = 100 mm
• Width = 60 mm

You can also add geometric constraints such as:

• Horizontal
• Vertical
• Coincident
• Parallel
• Perpendicular

The objective is to make the sketch properly defined.

Instead of relying on your mouse position, you're telling CATIA exactly how the geometry should behave.

Step 4: Exit the Sketch

Once your sketch is complete, exit the Sketcher.

You'll return to the Part Design environment.

Now comes the exciting part.

We're going to turn the 2D sketch into a 3D model.

Step 5: Create a Pad

Select your sketch and choose:

Pad

Enter a length of:

10 mm

Click OK.

Your 2D rectangle has now become a 3D solid.

This operation is one of the basic concepts you'll use repeatedly in CATIA.

Sketch → Pad → 3D Part

Step 6: Create a Hole Using Pocket

Now let's add a hole to the component.

Select the top face of your model.

Create a new sketch.

Choose the Circle tool and draw a circle.

Set the diameter to:

Ø12 mm

Position the circle using constraints so that it is located accurately on the part.

Exit the sketch.

Now select:

Pocket

Choose Through All.

Click OK.

You now have a hole in your component.

Step 7: Create Another Feature

Let's make the component more interesting.

Select another face and create a new sketch.

Draw a rectangle that represents a small cut-out.

Apply the required dimensions.

Then use:

Pocket

to remove the material.

This demonstrates an important CATIA workflow:

Create Sketch → Apply Constraints → Create Feature

You can repeat this process to gradually develop a more complex component.

Step 8: Add a Fillet

Sharp edges aren't always suitable for manufactured components.

To round an edge, select the edge and choose:

Edge Fillet

Enter a radius such as:

5 mm

Click OK.

The sharp edge will now have a rounded transition.

Fillets can be useful for both design requirements and manufacturing considerations.

Step 9: Understand the Specification Tree

Now take a look at the left side of your CATIA window.

You may see something similar to:

Part

↳ Body

↳ Sketch

↳ Pad

↳ Sketch.2

↳ Pocket

↳ Sketch.3

↳ Pocket.2

↳ Fillet

This tree tells the story of how your model was created.

If you change an earlier sketch or feature, later features can update based on the design relationships.

That's why understanding the tree is an important part of becoming comfortable with CATIA.

Step 10: Rotate and Inspect Your Model

Don't immediately save the model and move on.

Rotate it using the view controls and inspect it from different angles.

Ask yourself:

• Are all dimensions correct?
• Are the holes positioned correctly?
• Are the features properly aligned?
• Are there unnecessary edges or features?
• Does the final component match the intended design?

This habit helps develop design thinking, not just software skills.

What You Learned in This Tutorial

With this simple project, you've already explored several fundamental CATIA concepts.

CATIA SkillPurpose

Sketcher

Creating 2D geometry

Constraints

Controlling geometry and dimensions

Pad

Creating solid material

Pocket

Removing material

Fillet

Rounding edges

Specification Tree

Managing design history

These tools form a foundation for more advanced CATIA modelling.

Try This Practice Exercise

Now create your own version of the bracket.

Try these dimensions:

• Base length: 120 mm
• Base width: 70 mm
• Thickness: 12 mm
• Hole diameter: 10 mm
• Fillet radius: 6 mm

Then change the hole position.

Try adding another hole.

Try modifying the thickness.

Notice how the model changes when you modify the dimensions.

Don't just follow the tutorial—experiment with it.

That's where real learning begins.

What Should You Learn After This?

Once you're comfortable with basic Part Design, you can explore more CATIA areas such as:

Advanced Part Design

Learn:

• Shaft
• Groove
• Rib
• Slot
• Multi-section Solid
• Draft
• Shell

Generative Shape Design

Useful for creating more complex surfaces and shapes.

Assembly Design

Learn how multiple parts come together to create a complete product.

Drafting

Create detailed 2D engineering drawings from your 3D models.

Surface Design

Explore advanced modelling techniques used in automotive and product design.

Why CATIA Is Worth Learning for Mechanical Students

CATIA is more than a 3D modelling tool.

It introduces students to a structured way of thinking about product design:

Concept → Sketch → Constraints → Feature → Part → Assembly → Product

The more projects you create, the easier it becomes to understand how individual features contribute to a complete product.

For students interested in areas such as automotive engineering, aerospace, product development and mechanical design, developing strong 3D CAD skills can be a useful part of their technical learning journey.

Your First CATIA Model Is Only the Beginning

Your first CATIA model may have a few mistakes.

Your dimensions may not be perfect.

Your sketch may take longer than expected.

That's normal.

The important thing is to keep building.

Start with a simple bracket.

Then try a shaft.

Then a pulley.

Then a complete assembly.

With every project, you're not just learning another command—you are developing the ability to turn an engineering idea into a digital model.

Sketch it. Constrain it. Model it. Improve it.

That's how you start thinking like a CATIA designer.