Design and Prototyping¶

Design¶

During the CAD week, I explored and utilized Google SketchUp and Fusion 360 for modeling my 3D scanner project. These software tools enabled me to visualize concepts, create surface and solid models, and iterate on designs efficiently.

Google SketchUp¶

Selection Rationale: I opted to use Google SketchUp for its familiarity and efficiency in visualizing concepts and generating surface models. Having used SketchUp extensively since my school days, I find it to be the quickest method for conceptualizing designs and creating basic geometries.

Iterative Design Process:

Starting with Basic Shapes: I began the design process by conceptualizing the project using rough blocks or basic shapes, focusing on establishing the overall structure and layout.
Gradually Adding Complexity: As the design progressed, I incrementally incorporated additional details to refine and enhance the aesthetics and functionality of the project.
Iterative Refinement: Throughout the design process, I iteratively refined the project based on feedback and evaluation, aiming to achieve the desired objectives effectively.

Personal Opinion: Google SketchUp has been a staple in my design workflow, offering a user-friendly interface and intuitive tools for rapid prototyping and concept visualization. While SketchUp may lack some advanced features found in other CAD software, its simplicity and quick learning curve make it invaluable for iterative design and concept development.

Design 1 Final Project by naimalhajali on Sketchfab

Download Design 1 SketchUp File Download Design 1 STL File

Fusion 360¶

Exploration: In addition to Google SketchUp, I explored Fusion 360 to develop an alternate design of the final project. Fusion 360 is a cloud-based CAD/CAM tool that integrates design, engineering, and manufacturing processes into a single platform.

Usage: I utilized Fusion 360 to create 2D profiles, model solid bodies, simulate designs, and generate toolpaths for CNC machining operations. Fusion 360’s cloud-based nature facilitated seamless collaboration among team members and provided access to design data from anywhere with an internet connection.

Personal Opinion: Exploring Fusion 360 provided me with insights into its comprehensive suite of tools for 3D modeling, simulation, and manufacturing. While Fusion 360 may have a steeper learning curve compared to SketchUp, its depth of functionality and integration make it a powerful tool for realizing complex design projects.

D2 Final Project by naimalhajali on Sketchfab

Download Design 2 Fusion360 File Download Design 2 STL File

Prototyping¶

I utilized the CNC machining week to focus on prototyping the frame for the final project, where I designed and cut the frame pieces using the CNC machine from plywood.

I further refined the design of the frame for the 3D scanner project. Utilizing a combination of Google SketchUp and Fusion 360, I iteratively developed a robust and versatile frame tailored to the specific requirements of the 3D scanner.

Design Process Overview¶

Conceptualization in Google SketchUp: The design process commenced with rough sketches and basic shapes in Google SketchUp. By visualizing different layout configurations and component placements, I explored various design possibilities and established the foundation for the frame design.
Refinement in Fusion 360: Transitioning to Fusion 360, I translated the initial concept into a detailed and parametric 3D model. Leveraging Fusion 360’s advanced features, I focused on creating a design that prioritized structural integrity, ease of assembly, and compatibility with CNC machining processes.

Key Design Features¶

Parametric Design: The final frame design in Fusion 360 incorporates parametric modeling techniques, allowing for easy modification and adjustment of key parameters such as material thickness and component dimensions. This parametric approach enhances flexibility and facilitates iterative design refinement.
Integration of Functional Components: The frame design integrates various functional components necessary for the operation of the 3D scanner, including mounting points for sensors, actuators, and support structures. By strategically positioning these components within the frame, I optimized the scanner’s functionality and performance.
Optimized for CNC Machining: Throughout the design process, careful consideration was given to manufacturability and machining feasibility. By adhering to CNC machining best practices and design guidelines, I ensured that the frame components could be efficiently machined with minimal waste and downtime.

CNC Machining Process¶

Material Preparation and Fixturing¶

Material Selection: The process begins with selecting suitable materials for the frame construction, focusing on factors such as strength, durability, and machinability. For this project, 18mm plywood was chosen due to its stability and ease of machining.
Fixturing Setup: To ensure stability and accuracy during machining operations, the plywood sheet is securely fixed onto the CNC machine bed using screws. Proper fixturing is essential for minimizing material movement and achieving precise machining results.

Machine Setup and Toolpath Generation¶

Tool Selection: Careful consideration is given to selecting the appropriate tools for machining plywood, taking into account factors such as bit diameter and cutting depth. For this project, a 6mm 3-flute endmill was chosen to achieve clean and accurate cuts.
Toolpath Generation: Using software like VCarve, toolpaths are meticulously created to guide the CNC machine in cutting the plywood sheet into the desired shapes and dimensions. Parameters such as feed rates, spindle speeds, and plunge rates are adjusted to optimize machining efficiency and accuracy.

Machining Process¶

Initial Test Path: Before machining the entire set of components, a test toolpath is generated for a small section to evaluate joint fitting and tolerances. This step helps identify any potential issues or discrepancies in the machining process early on, allowing for necessary adjustments to be made.
Precise Cutting: With the toolpaths generated, the CNC machine precisely cuts the plywood sheet into individual components according to the design specifications. The use of CNC machining ensures consistency, accuracy, and repeatability in the manufacturing process.

Assembly of Frame Components¶

Assembly

During the assembly process, components are carefully assembled using techniques such as interlocking joints and adhesives to ensure tight tolerances and structural integrity. A rubber mallet may be used to seat joints and ensure a secure fit between components.

Testing and Prototyping¶

Protyping the Mechanincal Components:¶

To construct the arc mechanism of the 3D hand scanner, I connected a 12mm rod as the shaft. The rod was clamped between two pieces of plywood attached to the arc. The shaft was supported on the base using two bearings. A GT2 pulley was then attached to the shaft, allowing the stepper motor to drive it.

Protyping the Actuation:¶

I first clamped the nema 17 stepper motor to the base, and controlled it using an arduino and a cnc sheild with a A4988 driver.

This setup helped verify the motor’s operation and integration with the mechanical system.

I noticed that the motor is able to move the arc, but the most important factor affecting the movement is the balance of the arc. where the two sides of the arc, the top part where the phone mounts, and the bottom part with the backdrop should be equal in weight. As during testing I noticed that any imbalance would heabily affect the ability of the motor to drive and rotate and arc. I noted this, and kept it in mind for further developing the design.

After that I designed and printed the first version of the motor mount.

Testing the Scanning:¶

For initial testing, I attached a phone to the arc and conducted test scans (videos). These were processed into 3D scans using PolyCam to verify the accuracy and adjustability of the arc and overall design.

The scans where a success, as I verified the ability of the design and idea to create accurate scans of the hand. After this step I was able to continue with adding to the design and refining it.

Hand Scanning Test by naimalhajali on Sketchfab

Protyping Electronics¶

I prototyped the electronics and sensors on a breadboard to ensure functionality before designing a custom PCB tailored to the project’s exact needs. For the interface, I chose a 128x64 OLED screen, two buttons, and a potentiometer. The microcontroller used is a Xiao RP2040, and the motor driver is an A4988. An ultrasonic sensor was included for hand detection, and an RGB LED strip was added to illuminate the scans in a controlled manner and provide feedback to the users with different colors indicating different machine statuses.