WEEK 12 – Mechanical Design + Machine Design

Assignment

Group Assignment

Design a machine that includes mechanism+actuation+automation+function+user interface
Build the mechanical parts and operate it manually
Document the group project and your individual contribution

Group Work

Our group work is accessible HERE (add the link)

Project Work Description & Process

Introduction

This year, our FAB Academy 2026 Team decided to focus on improving and developing further the concept of the Automatic Writing/Drawing Machine proposed by the FAB Academy 2025 Team at UNNC Fab Lab previously. We decided to name our machine "AutoWD-2026", refering to "Automatic Writing & Drawing" machine "model 2026".

Mechanical Specifications

Description	AutoWD-2025	AutoWD-2026
# of Axis	3 Axis	4 Axis
Pen Holder	1-pen	6-pen (rotating)
Pen(s)	WhiteBoard Marker	BAOKE D290-12 Colour Markers
Bed Size (mm)	155x90	250x125
External Size (mm)	365x360x280	435x415x340
Frame Size (mm)	255x280x285	330x330x295
Aluminum Frame Profile	30x30 + 20x20	30x30
3D printed Components	PLA (Red & Black)	PLA (Green)
X Axis	42 Step Motor	42 Step Motor
Y Axis	42 Step Motor	42 Step Motor
Z Axis	Step Motor J75A64BT	28 Step Motor
B Axis	n/a	Servo Motor MG996R (360°)
Y & Z Movement	Smooth Rods + Lead Screws	Smooth Rods + Lead Screws
X Movement	10mm Belt + Timing Pulleys	10mm Belt + Timing Pulleys
Y Movement	T8 Lead Screws + Smooth Rods	T8 Lead Screws + Smooth Rods
Z Movement	T8 Lead Screws + Smooth Rods	T5 Lead Screws + Smooth Rods
Linear Actuator Carriage Plate	for 20x20mm Profile	for 30x30mm Profile

Electrical Specifications

Description	AutoWD-2025	AutoWD-2026
Motion Control	RAMPS 1.4 Shield + x3 A4988 Motor Driver	RAMPS 1.4 Shield + x4 A4988 Motor Driver
MCU	Arduino Mega 2560	Arduino Mega 2560
Power Supply	One External	Two External
Others	n/a	Dupont Jumper Wires

The pens/markers we selected (our new "short" ones below the "big" one from 2025 at the top of the picture)

STEP 1: Kick-Off Meeting

On the first day of our project, we organised a kick-off meeting to discuss what will be our "Mechanical Design & Machine Design" challenge this year. We all agreed on improving and developing further the concept of the Automatic Writing/Drawing Machine proposed by the UNNC FAB Academy 2025 Team.

Key improvements and devolpments proposed:"
1. Improve Z Axis (based on the past year experience)
2. Increase Bed Size (and therefore the machine size as well)
3. Add a Rotating Multi-Pen Holder (up to 4/6/8 pens)
4. Improve Ease of Assembling the Machine (mechanism alignments)
5. (Not implemented) Add an Automatic Paper-Roll Feeder (for continuous writting/drawing - e.g. Banner, etc)
Team Members's Key Responsabilities:
- Software & Electrical Control Engineer: Le LI
- Structural & Mechanical Engineer: Loïc FAULON
- Project Supervisors: Bob WU & Yaorun ZHANG
- Design & Debugging Experts: All of us 😃 😃 😃

STEP 2: CAD with SolidWorks (Loïc)

The CAD modelling process followed a well-planned, methodic, and progressive approach with a number of iterations depending on the components. The image below illustrates the numerous CAD files and folders created to support a clean organisation of the data and smooth process.

1. Modelling of the Frame

I have applied the "Weldments" with "Structural "Members" technique available in SolidWorks to model the whole structure of the frame from two very simple 2D sketches. Instead of modelling myself the T-Slot profile, I decided to look online for a database. Luckily, I found two manufacturers/suppliers, SLOTPRO and 80/20, with excellent catalogues to refer to and complete CAD Libraries... and the possibility to download them easily and install them in my SolidWorks' library. 😃 😃 😃

SLOTPRO and 80/20 website landing pages and Catalogues

Frame design in SolidWorks

2. Design of the Plastic Components in SolidWorks

The design of the plastic components in SolidWorks (all 3D printed along the development process) has been the most time-consuming activity. Sometimes, several iterations were needed due to functional, dimensional, and/or ease of assembly/disassembly refinements.

The Design & Development strategy applied has been to work from "Bottom-to-Top" of the machine, or from "Base-to-End" (Penholder), insuring all parts fitted well on the frame and between themselves, with good function, before starting the design of the next part/component.

Here is the design-flow of the parts/components:

    1. Frame Base Cover Caps
    2. Y Axis Locator Plate Front
    3. Y Axis Locator Plate Back (with step-motor)
    4. X Axis Support Right
    5. X Axis Support Left (with step-motor)
    6. Bed Plate
    7. Z Axis Support + Z Axis Support Belt Locker
    8. Z Axis Slider
    9. Rotational 6-Penholder

STEP 3: Manufacturing & Assembly (Loïc)

1. Production of the 3D Printed Components

For the manufacturing, we mainly used 3D Printing to produce our custom design components. All the them are made of a bright green PLA... hours and hours of days and nights production!

Generated Waste: (to be aware of...)
Because of supports needed for some parts and because of some iterations for design refinement and "fine-tuning", we did unfortunatly produce some waste as well. 😦 😦 😦