3D Scanning and Printing

Experimenting with 3D printers during the group project taught me some universal rules of FDM manufacturing. Most importantly, I learned that gravity is the biggest enemy of 3D printing; any steep overhang or long bridge requires proper consideration or support structures, otherwise the molten plastic will simply collapse. Furthermore, I discovered that precise tolerances are extremely important for manufacturing moving parts. Without leaving the exact clearance between parts, hinged joints will either completely fuse together during printing or be too loose to function.

Group Assignment Week 5

This week, I focused on applying 3D design principles to create an object that could only be manufactured using additive manufacturing technologies. I also digitized a physical object in detail using 3D scanning.

3D Design in CAD Software

As an Adventure Time fan, I decided to design an articulated BMO figure using SolidWorks. The joints presented a significant challenge. I needed to limit their range of motion for example, preventing the elbow from bending backward, and calculate the correct clearance to prevent the parts from fusing together during printing. Furthermore, their joints are a good practice in additive manufacturing, since using other technologies it is very difficult, I would say almost impossible, to generate these chain shapes due to the complex tool entry angles.

I designed the figure as a two-part assembly: the main body, which houses the articulated limbs, and a separate faceplate for the screen and buttons. This modular design allows me to 3D print different expressions and swap them out easily.

Design

BMO Body

The main body features chain-link joints with mechanical stops to prevent excessive bending. The iconic BMO lettering on the sides was created using extrusion cutting. To achieve a functional print model, I used reference drawings to separate the limbs from the body, maintaining the necessary tolerances for proper joint function.

Design

BMO Screen

The removable front faceplate features the screen and molded buttons. It connects to the main body using mounting posts that fit into matching indents. To ensure these connecting features worked perfectly, I incorporated a 0.2 mm tolerance, allowing the parts to fit together securely without being too tight.

BMO Parts

To get a realistic preview of the final result, I brought the individual components into a SolidWorks Assembly. I used the Mate tools to join the pieces digitally, ensuring that the modular design and the intended clearances worked perfectly together before sending anything to the 3D printer.

3D Scaning

My chosen object for 3D scanning was the Studio Series 44 Optimus Prime. It was a challenging model because of its high level of detail and many moving parts. To get a complete 360-degree scan, I had to reposition the figure to capture hidden angles. The hardest part was keeping its pose completely locked, any shift in the articulated limbs would make it impossible for the software to stitch the scans together.

For the 3D scanning portion of the task, I used the Shining 3D scanner EinScan-SE along with its software, EXScan S. Before scanning my object, I performed the necessary hardware calibration.

Board Placement and Alignment

To begin the calibration, I placed the calibration plate on the turntable support parallel to the scanner. It is essential to orient the plate exactly as shown in the 3D animation of the EXScan S software. I used the specific pattern of the largest white dots as a visual reference to ensure that both the left and right cameras could correctly recognize the grid.

Capture of Different Positions

The software requires a three-step sequence to properly align the dual cameras. For each step, I followed the blue animated guide on the screen, which told me how to adjust the rotation and position of the calibration board.

During the calibration process, the automatic turntable rotates precisely to allow the dual cameras to capture the reference board from a full 360-degree perspective.

White Balance

To ensure accurate color reproduction, the next step was to perform a white balance calibration. This allows the scanner's sensors to establish a baseline for true white under current lighting conditions.

Process

How to Scan

After calibrating:

Setup: Place the object on the turntable and adjust the camera's brightness/exposure.
First Scan: Run the automatic turntable scan to capture the initial geometry.
Repositioning: Flip or rotate the object and run additional scans to capture hidden angles.
Alignment: Ensure the software correctly merges the different scan passes.
Cleaning: Manually delete noise, artifacts, and the turntable base from the point cloud.
Meshing & Export: Generate the final watertight mesh and export the STL file.

The scan successfully reproduced most of the figure's fine details. However, the black parts, such as the wheels, were not scanned at all. This happens because dark colors absorb the scanner's structured light, preventing the cameras from capturing data in those specific areas.

Optimus by oski._.hgez on Sketchfab

The digitization process of the Optimus Prime figure perfectly demonstrates the true power of 3D scanning technology. Replicating such complex, organic, and highly detailed surface geometries from scratch would require hours of work using traditional 3D modeling software. In contrast, 3D scanning allows us to capture these physical details and convert them into a high-precision digital mesh in a fraction of the time, making it an incredibly efficient tool for reverse engineering and rapid replication.

Printing Process

Characterization

Creality Ender-3 V3 SE

To understand the design rules and manufacturing limits of my available equipment, I characterized my personal 3D printer.

Extruder: "Sprite" Direct Drive capable of handling PLA, PETG, and flexible filaments

Build Volume: 220 x 220 x 250 mm

Bed Leveling: Automatic (CR Touch sensor)

The printer handles angles up to 60 degrees successfully without needing support structures.

UltiMaker Cura

To prepare the model for manufacturing, I utilized UltiMaker Cura as my slicing software, translating the CAD geometry into the necessary G-code instructions.

Download UltiMaker Cura

Importing and Positioning

First, I imported the exported STL files into UltiMaker Cura. Using the software's basic transformation tools, located in the left panel, I positioned the main body and front plate within the Creality Ender-3 V3 SE's virtual build volume to optimize the print space.

Orientation Strategy

The orientation of the parts is crucial for a successful print. I made sure to place the flattest surfaces directly against the build plate to ensure strong adhesion. Additionally, I oriented the model so that the circular joints and pegs were parallel to the XY plane, thus preventing warping.

Print Settings Optimization

For the print settings, I selected a 5% Cubic infill. Since this BMO figure is primarily decorative, high structural strength isn't necessary, and this saves both time and material. To help with adhesion and complex geometries, I enabled a Brim and configured the supports to 'Touching Buildplate' only, which prevents the software from generating hard-to-remove supports inside the mechanical joints.

Slicing Preview and Verification

Finally, I used Cura's Preview (Layer View) to inspect the sliced model. This step is vital to visually verify how the brim, infill, and supports are generated layer by layer.

The initial 1 mm clearance gap was not enough to prevent friction between the moving parts. To fix this, I went back to CAD and slightly shrank BMO's main body while keeping the arms at their original size, which effectively increased the socket tolerance. Finally, to ensure the FDM printer could perfectly resolve these gaps without the walls fusing together, I imported the model into Cura and scaled everything uniformly to 170%.

Final results