5. 3D Scanning and printing¶

Group assignment:¶

• Test the design rules for your 3D printer(s)

To see our group assignment click here

Individual assignment:¶

• Design and 3D print an object (small, few cm3, limited by printer time) that could not be made subtractively

• 3D scan an object (and optionally print it)

Prelude¶

For the 3D design of our part, we used Autodesk Fusion 360 software and chose to model a Möbius strip.

The unique feature of this part lies in its geometry: it is a strip that rotates 180° around itself before closing, thus creating a continuous surface with a single side. This complex geometry cannot be achieved by simple extrusion or conventional material removal.

The modeling was therefore carried out using a sweep function along a circular trajectory, applying a gradual rotation to the section to generate the characteristic twist.

Given the continuity of the surface and the internal torsion of the part, certain traditional manufacturing methods (subtractive machining or simple molding) would be difficult or costly to implement.

Additive manufacturing (3D printing) is therefore the most suitable solution for producing this part, as it allows complex geometric shapes to be easily created without the need for specific tooling.

3D design¶

We used Autodesk Fusion 360 software to design our part in 3D. This parametric modeling software will enable us to design our Möbius strip, a geometric structure characterized by a single surface obtained by rotating a strip 180° around itself before closing it.

Steps to create a Möbius strip in Fusion 360¶

Create a new file

• Open Fusion 360.
  
• Create a new design File > New Design.

Sketch the base curve

• Create a sketch on a face plane (e.g., Front Plane).

• Draw a curved strip using the tool (Create > Arc > Arc with Center Point) with a radius of R=10 mm, which will represent the trajectory of your strip.

Create a new profile, preferably the one pointed to by the arrow.

Open a new sketch on the perpendicular plane. We will now draw the frame that will serve as a guide for our shape: Guide segments: Draw two segments with a length of L = 8 mm positioned at the ends of your previous sketch. The cutout profile: At the end of the right segment, draw a circular arc with a radius of R = 3 mm. This arc will be the signature of the shape that we will extrude later.

The idea is to achieve the following:

Go to the Surface > Sweep tab, select the profile and path, and enter a twist angle value of 90°. Refer to the image below for assistance.

Go back to the Solid tab, select Create > Thicken.

Look at the red box; it will allow you to make your sketches visible. The one we are interested in is the one still framed in red in the workspace.

Use the revolution tool to cut material

Now that we have successfully made our first bite into the material, we are not going to bother doing it again by hand all the way around the ring. We are going to use a powerful tool: Pattern on Path. Create > Pattern >.

Use the Bevel tool to soften the edges of your ring to improve its appearance.

In this latest video, you will see how to open your 3D model directly in your slicer. Go to File > 3D Printing. As the application we use: PrusaSlicer. Install it and select it from the drop-down list.

Generating the 3D print file¶

Once you confirm with OK, your Slicer will open automatically with the object already positioned on the tray. you will see the following image with your object on the simulation tray.

Here we are! Your model is now on the virtual plate of your Slicer. This is where you will define the manufacturing recipe that the printer will follow.

Configuring the settings

• For this object with complex geometries (Möbius), precision is key. Refer to the values circled in red in the image below to configure your print profile:

• Layer height: Ideally 0.12 mm or 0.16 mm to ensure the curves of the ring are smooth.

• Infill: A rate of 15% to 20% with a “Gyroid” pattern is recommended for its multidirectional strength.

• Supports: Essential! Activate the supports as they fit better into the cavities of your object without leaving too many marks.

Generating the G-Code

Once all the fields have been filled in as shown in the image:

• Check the position of the object on the plate one last time.
• Click on the Slice Now button.

The software will then calculate each movement of the nozzle, layer by layer. You will see an estimate of the printing time and the amount of plastic required.

3D printing¶

Turn on the 3D printer, insert the SD card and turn the white knob to select the file to be printed as shown below and click once on the knob to start printing.

The end result is a Möbius strip. Due to its complex geometry, it can only be produced using additive manufacturing processes.

🔔​🔔​🔔​🔔​ Download the 3D file in STL format

3D Scanning¶

3D scanning is a technology that captures the shape, dimensions, and sometimes the appearance (color and texture) of a real object to create an exact digital copy on a computer.

It's a bit like taking a photo, but instead of getting a flat 2D image, you get a volume that you can rotate, measure, and modify. There are several ways to scan reality, but we will use the application as KIRI Engine.

KIRI Engine¶

KIRI Engine is an online slicer (web browser-based) that allows you to prepare files for digital manufacturing without installing heavy software. You import your STL file, set the parameters, and it generates G-code ready for 3D printing or other machines.

3D scanning process¶

• download and open the appaction on your phone
• Click on the button in the middle

• Click on Picture capture > Take pictures.

• As illustrated in the image below, the application offers two photo-taking modes for 3D scanning:

(1) keep the object stationary and take photos all around it, or 

(2) turn the object over and take photos.

As a model, I opted for a stack.