The MaxA3 is an upgraded version of the Poly Plot, optimized by debugging its mechanism, kinematics, and design to enhance performance, compactness, and user-friendliness.

Designed as an open-source product, making CNC plotting technology accessible to new makerspaces in government high schools.

Built under the Centre for Early Innovation initiative, this project, a collaboration between FabLab Kerala and the MIT Center for Bits and Atoms , aims to simplify the understanding of CNC motion systems, digital fabrication, and automation for students.

Max A3 demonstrates how computer-controlled machines bring digital drawings to life with precision and creativity.

After the success of Poly Plot, the team envisioned a smaller, classroom-friendly version that could be easily deployed across school makerspaces.

The goal was to create a cost-effective, modular CNC system that retained the principles of the larger machine, automation, tool changing, and precision motion, while being simpler, lighter, and ideal for learning environments. Thus, MaxA3 was born as a portable educational variant of Poly Plot.

Beyond engineering and education, MaxA3 also celebrates creativity. Its precise motion system allows it to draw intricate patterns, geometric designs, and even abstract art, bridging the worlds of technology and artistic expression.

• Machine Type: Educational 3-axis CNC plotter (A3 format).

• Motion System: H-Bot configuration for smooth and synchronized XY motion.

• Tool Changer: Flexure-based iris mechanism with magnetic latch system , compatible with 9–13 mm pens using PG13 connectors.

• Work Area: A3-sized bed (approx. 297 × 420 mm).

• Structure: Lightweight modular frame designed for easy assembly and maintenance.

• Design Software: Modeled in Fusion 360 .

• Machines Used: 3D Printer, Laser Cutter, Waterjet Cutter, Flatbed Cutter.

• Controller: ESP32 with G-code interpreter firmware for motion control.

• Power & Electronics: Custom control board with DRV8825 stepper drivers and integrated end stops.

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MaxA3 works on the principles of precision motion, automation, and modularity. It uses an H-Bot mechanism for smooth XY motion, keeping the front open for easy paper access.

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The H-Bot configuration was chosen over Core XY because it allows the ATC docking station to be positioned along one side of the machine, keeping the front area open for easier paper placement and better visibility during operation.

The flexure-based magnetic tool changer allows quick swapping of pens using PG13 connectors. A pen-height calibration tool and magnetic paper holder ensure accuracy and stability.

It’s modular design simplifies assembly and learning, making it ideal for educational makerspaces.

The journey of Max A3, from early design sketches and CAD modeling to prototyping, fabrication, assembly, and final testing. Each phase reflects the iterative design process, hands-on experimentation, and continuous refinement that shaped the machine into its final form.

Detailed engineering drawings were created for each component to ensure accuracy during fabrication. The MDF bed was designed and manufactured using the Zünd digital cutter, allowing for clean, precise cuts and fast prototyping.

The MS (Mild Steel) base plate was subtractive manufactured using the OMAX waterjet cutter, chosen for its high precision and ability to cut complex geometries without thermal distortion.

After assembly, the mechanical and motion systems of Max A3 were rigorously tested to ensure smooth and precise operation. The process included calibrating the H-Bot motion , verifying ATC tool changes , and fine-tuning the Z-axis lift mechanism for consistent pen contact.

A cardboard form mockup of Max A3 was created during the early development phase to study the machine’s proportions, component placement, and motion range . This quick, low-cost prototype helped the team validate design choices before moving into fabrication.

The ATC in MaxA3 solves the challenge of accommodating pens with different diameters while keeping them perfectly centered during operation .

It features a novel flexure-based iris mechanism with an adaptive concentric design that automatically aligns each pen to the center.

Using a magnetic latch system and PG13 connectors, the tool changer enables smooth, motor-free pen swaps for multi-color plotting, ensuring precision, repeatability, and ease of use in an educational setup.

To prevent the ink from drying out when the pen remains exposed for long durations, a silicone cap was custom-casted to cover the pen tip when not in use. The flexible silicone material creates an airtight seal, maintaining the pen’s moisture and ensuring consistent ink flow during future operations.