Ball In A Box (Precision Machined on Makera Z1)

Have you ever wondered how a loose aluminum sphere gets trapped inside a solid metal cube without any seams or welds? This classic machinist puzzle is machined from a single solid block of aluminum!

In this beginner-friendly step-by-step guide, you will learn how to turn a standard Makera aluminum block into a free-floating sphere trapped inside an open cube frame.

🛠️ Required Materials & Tools

Materials:

Aluminum Stock: 6061 Aluminum (~35x35mm stock, cut to approx. 36mm length)
3D Printed Helper Clamp: (Included in the files: Ball-In-Box Clamp 3MF)
3D Printed Display Stand (Optional): (Included in the files)

CNC Machine & Accessories:

Machine: Makera Z1 (or Carvera / Desktop CNC)
Workholding: Makera Low-Profile Vise
Probing: Makera 3D Touch Probe or 3D Touch Rod for conductive materials

End Mills:

Tool 1: 4mm Single Flute Flat End Mill (Roughing & Pocketing)
Tool 2: 4mm Ball Nose End Mill (3D Contouring of the sphere)
Tool 3: 3.175mm x 90° Chamfer Bit (Deburring & Edges)

🪜 Step-by-Step Guide

Step 1: Stock Preparation (Squaring the Cube)

Cut a piece from your 35x35x100mm Makera stock to a length of roughly 36mm using a bandsaw or handsaw.
Clamp the raw block into the Low-Profile Vise.
Mill and face all sides down until you have a perfectly square 34 x 34 x 34 mm cube.

Step 2: Probing & Setup (Side 1)

Clamp your prepared 34mm cube securely in the vise.
Insert the Makera 3D Touch Probe.
Probe the Top-Center (or Top-Left Corner) and set your work coordinate origin (X0, Y0, Z0).
Remove the probe and load your milling tools into the ATC/spindle.

Step 3: Milling Sides 1 to 5

For each of the first 5 sides, the machine will perform three operations:

Adaptive / Pocket Clearing: The 4mm Flat Endmill mills the outer window openings and roughs the sphere profile inside.
3D Finishing: The 4mm Ball Nose mill creates the smooth, curved surface of the inner ball.
Chamfering: The 90° chamfer bit adds a clean bevel to the window frame.

Note: After each side is finished, unclamp the cube, rotate it to the next unmachined side, re-probe, and run the job. Repeat this for sides 1 through 5.

Step 4: The Trick for Side 6 (Locking the Ball)

⚠️ Important: When you mill the final (6th) side, the ball will completely separate from the outer frame. If it spins freely, it can damage the tool or ruin the finish!

3D-print the provided “Ball-In-Box Clamp” (PLA/PETG, high infill).
Place the 3D-printed clamp inserts into the cage to wedge the ball firmly in place.
Clamp the assembly into the vise with the final unmachined face pointing up.
The 3D clamp has a dedicated cutout so the 3D Probe can still touch the raw aluminum corner to find XYZ zero!
Run the final operation for Side 6.

Step 5: Post-Processing & Display

Remove the finished cube from the vise and take out the clamp inserts. Your ball should now roll freely inside the box!
Remove any minor burrs with a deburring tool or scotch-brite pad.
(Optional) Blast the piece with glass beads for a stunning matte-satin finish.
Place your finished showpiece on the 3D-printed display stand!

Precision Required CNC Projects