FreeCAD – Part 4: Middle Shelf

In this lesson, we design and integrate the middle shelf for the Millie Mini AI robot. This component serves as a core internal structure that supports alignment, mounting, and future expansion.

The lesson focuses on clean, parametric part design and shows how a newly created body is prepared for assembly by adding mounting features, converting it into a Part, and placing it into the existing assembly.

Designing the Middle Shelf

We begin by creating the middle shelf as a new body and defining its overall shape and dimensions.

Steps covered in this lesson:

• Creating a new body for the middle shelf

• Defining the shelf profile with a sketch

• Applying parametric dimensions

• Ensuring correct orientation relative to existing components

This establishes the middle shelf as a structural element that fits cleanly within the robot’s layout.

Adding the Main Neck Hole

Next, we add the main neck hole that allows the middle shelf to align with and support the robot’s upper structure.

In this lesson, we:

• Create a sketch on the shelf surface

• Define the neck hole location precisely

• Apply constraints to keep the hole centered and editable

• Use a Pocket to cut the hole through the shelf

This hole becomes a key alignment feature for the overall robot structure.

Creating the Mounting Hole Grid

With the main structure in place, we add a grid of mounting holes to support future components and expansion.

In this lesson, we:

• Lay out a hole pattern using sketches

• Apply consistent spacing and constraints

• Design the grid for flexibility and reuse

• Cut mounting holes through the shelf

This grid allows additional components to be mounted later without redesigning the shelf.

Preparing the Shelf for Assembly

Once the geometry is complete, we prepare the middle shelf for integration into the robot assembly.

In this lesson, we:

• Convert the body into a Part

• Organize the part clearly for assembly use

• Load the new part into the existing assembly

• Position it relative to previously created components

This step transitions the shelf from a standalone model into a reusable assembly component.

Result So Far

By the end of this lesson, you will have:

• Created the middle shelf as a parametric body

• Added a main neck hole for structural alignment

• Designed a mounting hole grid for future expansion

• Converted the shelf into a Part

• Inserted the new part into the robot assembly

At this stage, the middle shelf is fully integrated into the Millie Mini AI robot structure.

What’s Next

In the next lesson, we’ll continue building out the internal structure and refining how components mount and align within the assembly.

We’ll:

• Add additional structural parts

• Refine placement inside the assembly

• Continue preparing the robot for hardware mounting

This is where the internal layout starts to support real-world building and expansion.