Manuel Ignacio Ayala Chauvin

1. Evaluation of Design Rules for 3D Printing

1.1. Materials and Methods

• Printer used: Bambu Lab X1 Carbon
• Material: PETG
• Modeling software: SolidWorks
• Slicing software: Cura / PrusaSlicer / Bambu Studio
• Key parameters:
  • Layer resolution: 0.2 mm
  • Infill: 20%
  • Extruder temperature: 220°C
  • Bed temperature: 55°C
  • Print speed: 50 mm/s

1.2. Test Designs

Specific models were created to systematically assess the critical design rules in additive manufacturing:

• Supports: Overhang tests at 15°, 20°, 30°, and 45° to determine the critical angle for unsupported structures.
• Bridges: Horizontal spans of 5 mm, 10 mm, and 15 mm to assess the bridging capacity of the material.
• Dimensions and Tolerances: Sets of components printed with small tolerance differences to evaluate achievable precision.
• Anisotropy: Structural differences evaluated along print directions due to layer adhesion weaknesses, especially in the Z-axis.

2. Design and Fabrication of a Non-Subtractive Object

The objective was to design and manufacture a 3D object that would be impossible to create using subtractive methods such as CNC milling, turning, or laser cutting. To achieve this, a complex structure was designed in SolidWorks incorporating internal cavities, intricate interlocking geometries, and enclosed voids that only additive manufacturing can realize.

2.1. Parametric Design Approach

A parametric modeling strategy was adopted, where key dimensions such as wall thickness, bridge length, internal clearance, and overhang angles were defined as variables. This allowed for dynamic adjustments and fine-tuning of the model to optimize it for 3D printing constraints. Parametric design not only accelerates prototyping but also enables customization and iterative refinement without redrawing the model from scratch.

This figure shows the digital 3D model designed using parametric tools in SolidWorks. The structure includes suspended bridges, internal channels, and closed volumes that highlight the unique capabilities of additive manufacturing. Adjustable features such as bridge length and cavity dimensions can be easily modified thanks to the parametric nature of the design.

This figure presents the final physical object after 3D printing. Critical details like unsupported bridges, enclosed cavities, and overhanging features were successfully fabricated without post-processing or internal support removal, demonstrating a successful application of Design for Additive Manufacturing (DfAM) principles.

2.2. Challenges Encountered

During the design and fabrication process, several challenges were identified:

• Internal Supports: Enclosed cavities required careful design to avoid the need for internal supports that could not be removed post-printing.
• Overhang and Bridging Management: Some sections with bridges exceeding 10 mm showed slight sagging, requiring design adjustments or printing orientation changes.
• Dimensional Accuracy: Fine clearances in interlocking parts had to account for the typical 0.2–0.4 mm tolerance variation inherent to FDM processes.
• Print Orientation: Strategic orientation was necessary to balance surface finish quality, minimize support material usage, and ensure mechanical strength in critical areas.

2.3. Lessons Learned

This assignment provided a deeper understanding of how to apply Design for Additive Manufacturing (DfAM) principles, leverage parametric modeling to optimize designs, and anticipate real-world fabrication constraints during the digital design phase. It also reinforced the importance of prototyping iterations when dealing with tight tolerances or complex geometries.

3. 3D Scanning of an Object

3.1. Scanning Methods

Two methods were applied to capture the three-dimensional geometry of a physical object:

Mobile Phone Scanning

• App used: KIRI Engine
• Procedure:
  • Multiple photos were taken from various angles around the object.
  • Images were processed via photogrammetry to reconstruct a 3D model.
  • An STL file was generated for visualization and printing purposes.

Dedicated 3D Scanner (Optional)

Using a dedicated 3D scanner (if available) significantly improves resolution and detail, especially for complex textures or intricate surfaces.

Practical Recommendations: Ensure diffuse lighting, avoid reflective or translucent materials, and maintain consistent coverage of the object.

Figure 1 - Mobile 3D Scanning Process:

The image illustrates the scanning setup using a mobile phone. A series of photographs were systematically captured from multiple angles around the object to ensure complete surface coverage, an essential step for successful photogrammetry reconstruction.

Figure 2 - Reconstructed 3D Model:

This figure shows the resulting 3D model generated after processing the captured images. The mesh was exported in STL format, highlighting the object's main features and geometry suitable for further use in digital applications or 3D printing.

Week 5: Conclusion

During Week 5, we consolidated essential skills in additive manufacturing and 3D digitalization. Through practical exercises, we gained a better understanding of how to adjust print parameters, evaluate physical limitations, and design with an additive manufacturing mindset (DfAM).

Regarding 3D scanning, the experience highlighted the technical challenges associated with mobile photogrammetry and the critical importance of capturing high-quality input images. These skills open the door to applications such as digital reproduction of objects, reverse engineering, and heritage preservation.

Key Lessons Learned:

• Not all geometries are feasible without supports; understanding limitations during the design phase is critical.
• Mobile phone-based 3D scanning is powerful but still limited compared to professional equipment.
• Additive manufacturing complements but does not replace subtractive methods; each has its optimal application fields.

Recommendations for Future Projects:

• Perform printer calibration routines regularly.
• Account for material anisotropy when designing functional parts.
• Plan 3D scans with priority on lighting, coverage, and consistency.

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