Week 7: Computer-Controlled Cutting – CNC Shenanigans & Functional Chaos

Group Assignment

You can refer to my Fab-mate Samruddhi's page

Meet the Beast: The CNC Machine 🦾

This week, I got to work with the Numac Hightec CNC machine, powered by a Richmond controller. If you’re wondering what CNC stands for— Computer Numerical Control—it’s basically a machine that listens to a computer’s precise instructions and cuts, carves, and crafts materials with robotic accuracy. Think of it as a giant robotic sculptor, except it doesn’t get tired, complain, or ask for coffee breaks.

Here’s how it works in a nutshell:
🔹 You feed it a digital design (a CAD file).
🔹 The machine reads it and translates it into G-code, the CNC’s secret language.
🔹 A spinning bit (aka end mill) cuts the material precisely based on the instructions.
🔹 The result? Perfectly cut pieces, ready for assembly (or accidental disasters if you ignore safety!).

Safety First (Because Limbs Are Important) 🦿🦾

At FabLab, safety training always goes one step beyond what we expect. Akhilesh Sir gave us a thorough walkthrough of:
✅ How to operate the CNC machine.
✅ Where the sensors are and what the machine can’t do (yes, it has limits).
✅ Where and how to clamp materials securely.
✅ Changing bits (without causing mini heart attacks).
✅ The risks of improper use—this part got real when we heard about an accident that happened before. A sobering moment.

Some CNC Rules to carve in your mind 🧠:

🔹 Closed-toe shoes only – Because dropping a heavy wood panel on your foot is not a vibe.
🔹 No loose clothing or accessories – Unless you want to become part of the CNC machine.
🔹 Proper material loading/unloading – Because gravity exists, and so do expensive materials.

Project 1: The Stand-Up Desk – Built for the Best (Me 😎)

A while back, I built a stand-up desk using this very machine. The project brief was simple:
📌 Create a surface that facilitates or delights a specific audience.
So, naturally, I designed it for the most amazing person I know—ME!

Here’s my reasoning:
🔹 I can’t work in a mess – If things are in sight, they’re in my mind. So, I designed it to hide away clutter.
🔹 I prefer standing while working – Sitting all day is overrated.
🔹 I wanted it compact & functional – Minimal footprint, maximum utility.

So, I kept the design bare bones, making sure it’s strong, simple, and space-efficient.
📂 CAD file? Check!

⚙️ CNC machining? Done!

🛠️ Finishing & assembly? Nailed it!

📸 Final Hero Shot? Chef’s kiss.

Project 2: The F1-Inspired Napping Chair – Because Work-Life Balance Exists 🏎️💤

This one’s still in the pipeline, but let’s talk about the idea.

The thought process:
💡 F1 drivers spend hours in a reclined position while driving at insane speeds.
💡 Naps are crucial.
💡 What if I made a chair that mimics that reclined position?

And just like that, the F1 Napping Chair was born (in my head).

Design Process:

✏️ Sketching Forms – I kept sketching until I found a shape that looked right.
🖥️ 3D Modeling in Blender – This step was crucial to ensure fabrication would be smooth.

🎨 Renders? Check!

🔪 Execution? Um…

Well, here’s the thing—my first design was TOO complex. It would take way too much material, time, and effort to cut and assemble. So, I’m back to simplifying it before sending it for CNC cutting. Stay tuned for the final version!

Wrapping Up 🛠️

An amazing week with tons of hands-on learning. CNC cutting is a game-changer, but also a patience-tester. Excited for what’s next! Onward to the next adventure! 🚀

Revisiting CNC

I realised that my initial idea would have taken weeks to cut and months to assemble (if at all). I wasn't ready to let go off the F1 idea yet. I thought I could do something around the way the drivers sit in the car.

Napping chair V2

It was time to take another crack at the napping chair idea. With the seating postion in mind I started making the CAD file for this idea in Fusion 360.

CAD

I used Fusion 360 to model my idea for a lay-down napping chair. I learnt a few tricks along the way, and this section is where I ll talk about them. If you click on modify>Combine. you get to select a target body( to be worked upon) and a tool body(the one doing the work). Here for instance I had to create slots for my cross braces that I used on my chair. So I just had to select them as my tool body and click on the Cut option. Its also important to select the Keep tool body option or else they would be deleted after creating the slots. If you are to translate your individual pieces from your model, to one plane for setting up the CNC process, you can use the Align option in the Modify section. This saves time and you dont have to eyeball the rotation for any part risking the dimensions and/or misfits post cutting.

CNC

Once all the parts are aligned to one plane preferably the Top plane, I had to setup my file for CNC cutting. To this first we have to change from Design mode to Manufacture mode Once inside the Manufacture workspace, we have to create a new setup. Here you have to specify the process that you want to do, select your project bodies that you want to cut and most importnatly, specify the origin, in my case it was the lower left point on the top plane of my stock. After the stock is set, we have to select what kind of function we need the machine to perform. I chose 2D contour. After selecting the 2D contour,first we have to select the tool we are using. These are the parameters that I have prefitted. These settings were derrived from the group assignment. This is the tool selecting menu, I used the 6mm flat end mill, you can search the profile of the bit that you are going to use. After we set all the parameters, its time to select the profiles that you want to cut. This is in the geometry section of the 2D contour. CLick on chain selection and click the bottom of the model. Then I moved to the last part of setting up the CNC function, specifying passes required. I set mine to dive 3mm in every pass. I was cutting through 12 mm of ply. This meant it would do 4 passes per piece.
Repeated the same for setting up the second part of cutting, just this time I used the drill function, instead of 2D contour.

Milling on CNC

Once all the files are ready we export it as an NC program. Then I loaded my 12 mm ply sheet on the CNC machine and clamped it down to the machine. These are the clamps I used.

Setup

Our CNC machine is operated by the Richmond Auto controller. This is what it looks like. The X+/X-,Y+/Y- & Z+/Z- are used to control the spindle position, the XY0 and Z0 are used to set the specified point as the origin. Once the origin is set I clicked on the run pause button to access my file from the USB drive that i had connected. The exported NC program is then selected. Et viola! Cutting begins! To keep the motor cool we have water running through it constantly. We use a bucket of water and a pump to do this.

The cutting time for all parts was about 50 mins. With all these parts cutout, I was standing in splinter city. In simpler words, the edges needed some sanding. So i brought out our good old, handheld sander. This is how the finished pieces came out.

With my sanded parts ready it was time to assemble! Some pieces needed some tapping with a mallet. I also needed few helping hands, both on & off camera!

And after all this heavy lifting, sanding and hammering, my creation had come to life!

Hero Shots

Design files

Fusion model Layout 1 Layout 2 NC program 1 NC program 2 NC program 3