3D Scanning and Printing

Group Assignment: Clearance Test

My documentation for this assignment can be found in my group's site. I worked with Max Negrin, McKinnon Collins, and Oliver Abbott.

To perform the clearance test, I first searched the internet to understand what I needed to do, and ended up finding this design from Printables.

This design tests clearances from 0.10 mm up to 0.35 mm, and adds additional functionality by showing the clearance with joints. Doing so prevents each part from falling out and makes the design more interactive.

I then downloaded the design and printed it through the Bambu software on a Bambu A1 Mini. Here is what the final result looked like.

As expected, the joint with .35 mm of clearance moved much more freely than the joint with .10 mm clearance, who could barely move within the socket. As the clearance increased, the mobility of each joint increased in correlation. Since each joint is a separate, individual part, removing this design from the Bambu hot plate was particularly time-consuming. Here is what the design looks like when each joint is moved.

Individual Assignment: Torus Structure

One task of this week's individual assignment was to create and print a 3D design that cannot be made subtractively (i.e. through milling). For this, I decided to create a 3D torus-shaped lattice structure. This design cannot be replicated subtractively because it contains a hollow inside with spaces that cannot be reached by traditional drilling heads/milling bits.

Designing the Structure in Fusion360

To create my design, I utilized Fusion360 and started in a new design from there. I am most familiar with the Fusion360 workspace, so using it made the most sense to me. First, I created a new sketch on the XY axis and placed a circle with a diameter of 40.00mm at the center.

Then, I created a new sketch on the XZ axis and, starting from the circumference of the circle, created a 15.00mm construction line stemming upwards. At its endpoint, I then placed a center square with side length 2mm.

To create a segment of the torus shape, I used the "Sweep" feature and selected the 2mm x 2mm square as the profile and the circle as a path. With both selected, it gave me the option to set distance, taper angle, twist angle, orientation, and operation. I set the distance to 5/13, the twist angle to 360 degrees, and the orientation to perpendicular. All other settings were kept default.

Then, to create the torus shape, I used the "Circular Pattern" feature and selected the Z-axis as the axis the shape will repeat around. This created 13 copies of the original sweep to complete the torus shape.

Finally, to complete the design, I used the "Mirror" feature on the entire object. This mirrored the shape and created the lattice pattern.

Here is what the final design looks like.

The file can be downloaded from here.

Below is an interactive 3D plot of the final torus lattice structure design.

Exporting and Preparing for Print

With my design finalized in Fusion 360, the next step was to prepare it for 3D printing. To do this, I exported the design as a .stl file, which is the standard file format for 3D printers. I right-clicked on the design in the model tree and selected Export. From there, I chose .stl as the file format and saved the file to my computer.

Once I had the .stl file, I opened the Bambu software and imported the design. The Bambu software is the slicing software designed specifically for Bambu printers. It allows you to configure print settings, preview how the printer will slice the design, and prepare everything before sending the job to the printer.

In the Bambu software, I reviewed the design and configured the print settings for the Bambu A1 Mini. Since the torus lattice structure contained internal voids and overhanging elements that would not be able to support themselves during printing, the software automatically generated support structures. I reviewed the support placement to make sure they would not damage critical areas of the design, and then confirmed the settings. Once everything looked correct, I sent the print job to the Bambu A1 Mini printer.

Print Results

The print completed successfully. Here is what the design looked like immediately after printing, complete with the support structures still attached.

Removing the Supports

Once the print was finished, I began the process of removing the supports. This task proved to be particularly challenging due to the complex structure of the lattice torus. The supports were tightly woven throughout the internal voids and lattice sections, making them very difficult to access and remove without causing damage.

The interconnected nature of the lattice meant that each support strand was interwoven with multiple parts of the design. Removing them required careful and deliberate work to avoid snapping critical structural elements of the lattice. I had to work methodically, using pliers and other removal tools to carefully break away each support piece. In several areas, the supports had adhered so firmly to the lattice that extra caution was needed to avoid damaging the delicate sections.

The time spent on support removal was significant, but the careful approach ensured that I did not cause any major damage to the final print.

Here is what the final design looked like after all supports were successfully removed.

Individual Assignment: 3D Scanning with Polycam

Another task of this week's individual assignment was to perform 3D scanning. 3D scanning is the process of capturing the physical shape and appearance of real-world objects and converting them into digital 3D models. This is useful for creating digital replicas of objects for documentation, reverse engineering, or further modification in CAD software. 3D scanning allows you to capture complex geometries that would be difficult to model manually.

To perform my 3D scan, I utilized the Polycam app. Polycam is a mobile application available on iOS and Android that uses photogrammetry to generate 3D models from a series of photographs. The app processes multiple images taken from different angles and uses algorithms to reconstruct the geometry and texture of the scanned object.

Scanning a Tissue Box

For this assignment, I initially attempted to scan a bag of Doritos. However, after taking several photos and attempting to process them, I discovered that the bag was too reflective for the Polycam app to capture properly. The shiny, metallic surface of the Doritos bag caused reflections that interfered with the photogrammetry process. This error was pointed out to me by Fab Academy graduate Andrew Puky, who explained that reflective surfaces do not work well with photogrammetry-based scanning because the reflections confuse the algorithms trying to identify consistent features across multiple photos.

After learning about this limitation, I chose to scan a tissue box instead. The tissue box had distinct features and a rectangular shape with a matte finish, making it much easier to capture. Here is what the tissue box looked like before scanning.

To begin the scanning process, I opened the Polycam app on my phone and selected the Photo Mode option. This mode allows you to take multiple photos of an object, which the app will then process into a 3D model. I positioned the tissue box on a flat surface with good lighting so that the app could capture clear images from all angles.

I then walked around the tissue box, taking photos from different perspectives while keeping the object centered in the frame. The app provided real-time feedback and guidance to help ensure I captured enough detail. I made sure to take photos from above, below, and all sides of the tissue box to give the app sufficient data to reconstruct the full geometry.

Once I finished taking photos, I uploaded them to the Polycam app for processing. The app analyzed the images and generated a 3D model of the tissue box. The processing took a few minutes, after which the app displayed the completed scan.

Scan Results

The scan completed successfully and captured the general shape and features of the tissue box. Here is what the final scan looked like.

The scan accurately represented the proportions and structure of the tissue box, though some fine details and textures were not as sharp as the original object. This is a common limitation of photogrammetry-based scanning, especially when using a mobile device.