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7. Computer Controlled Machining

This week, I explored CNC (Computer Numerical Control) machining, which allows us to cut large sheets of material like plywood, MDF, and acrylic with precision. The goal was to design, prepare, and mill a large structure using a CNC router.

Part 1: Understanding

What is computer controlled machining?

CNC (Computer Numerical Control) is a way of controlling machines using a computer. Instead of cutting or shaping materials by hand, a CNC machine follows a pre-programmed design to cut, drill, or carve materials like wood, plastic, and metal with high accuracy.

Types of CNC Machines

CNC Milling Machine: A computer-controlled machine that cuts and shapes materials using a rotating cutter.

CNC Router: Similar to a milling machine but mainly used for cutting wood, plastic, and soft metals.

CNC Plasma Cutter: Uses a hot plasma torch to cut through metal quickly and precisely.

CNC Lathe: Spins the material while a cutting tool shapes it, mainly for making round objects.

CNC Waterjet Cutter: Uses high-pressure water (sometimes mixed with sand) to cut through almost any material.

Riidl CNC Machine

Our lab has the Numac Hitech CNC machine with a bed size of 8' x 4'(2400 mm x 1200 mm). It is a 3 axis machine, meaning it moves in the X, Y, and Z directions for precise cutting and shaping.

Here’s how it works:

  • You design on a computer using CAD (Computer-Aided Design) software. (I prefer working on Fusion)
  • The design is converted into NC programme, a special language that tells the machine what to do.
  • Once that is done you can load your material on teh machine.
  • A suitable cutting tool (milling cutter) is attached for the required job.
  • Then you can start the job and the machine moves the cutting tool according to the programmed design, removing material bit by bit.
  • The result? Perfectly cut pieces which will be ready for assembly.

Part 2: Group Assignment

Learnings

Part 3: Project 1 - Making something big

The Idea

This week I wanted to design a piece of furniture that is both fun and functional. The idea of a chair that can change between a rocking chair and a regular chair felt exciting because it gives users more flexibility. Instead of having two separate chairs, one design serves two purposes—a relaxing rocking mode and a stable sitting mode.

This also makes the chair more space-saving and practical, which is useful for small homes or creative spaces.

Bauhaus Influence

The Bauhaus movement is all about simple, functional, and beautiful design. It avoids unnecessary decoration and focuses on clean geometric shapes and practical use. My chair follows this philosophy because:

  • It is simple in form, using a semicircle and straight lines.
  • Every part has a function, making it practical and not just decorative.
  • Use of boldd primary colours

Designing the Chair

Sketching

To bring my idea to life, I started by sketching different variations of the chair, focusing on how it would transition between rocking and stable modes. I ensured the structure was balanced and the rotation was smooth.

Prototyping

Creating the CAD Model

I used Fusion 360 to create a 3D model of the chair. This helped me finalize the dimensions, joints, and weight distribution. Since the chair needs to support a person’s weight while rocking, I reinforced the design with strong joints and a wide base.

CAM and Toolpath Preparation

Once the design was finalized, I moved to CAM (Computer-Aided Manufacturing) to generate toolpaths for CNC cutting.

Part 4: Project 2

I, along with the help of my friends Samurudhi Rovalekar and Kanika Kadam, designed and fabricated large 3D letters for TOSS, the annual sports event at Somaiya Vidyavihar University. The objective was to create a bold and striking installation that would serve as a visual centerpiece at Somaiya Cricket Ground, Sion.

We first sketched out the letters, ensuring they were aligned with the official TOSS branding. Using Adobe Illustrator, we traced the TOSS logo. This vector outline ensured our design could be scaled up without pixel disasters.

Once that was done the vector file was exported as a DXF and imported into Fusion 360 for proper dimensioning. Here, we adjusted proportions, alignment, and material thickness because nobody likes wobbly letters.

Before starting with the cutting we had to set up the manufacturing process in Fusion 360. This step ensured that the cutting paths, speeds, and depths were optimized for clean and precise cuts.

Once our design was ready it was time to cut out the pieces. The CNC machine milled the letters and after that we went out to asembled the pieces.

The Challenge: Working with Flex Ply

Unlike regular plywood, flex ply has a mind of its own—it bends, curves, and refuses to behave. While this material was necessary for achieving the desired shape. Clamping, aligning, and reinforcing the pieces required extra effort and patience. Despite the challenge, we successfully assembled the installation. And the last step was painting

The final Output