Fab Academy 2026
Week 7
Computer-Controlled Machining

Computer-Controlled Machining

Designing something big for CNC machining.

Assignment Goal

For this week, the individual assignment was to make something big, around meter-scale, using computer-controlled machining. The goal was to design, mill, and assemble a large object. Extra credit options included not using fasteners or glue, adding curved surfaces, and using three-axis toolpaths.

My original plan was to make a C-shaped TV tray or side table. The idea was to have a top surface, vertical legs, and a C-shaped bottom base. The tray would slide around a couch or chair, almost like a small work table for a laptop, food, tools, or whatever I was working on.

Project Limitation

The biggest problem this week was machine access. I did not have access to a large wood CNC router or a full wood shop that could cut something this big out of plywood or sheet material. Because of that, I was not able to physically mill and assemble the full-size version of this project.

Instead of pretending I cut it, I made a design model in Tinkercad to show what I wanted to build and how the parts would fit together. If I had access to a large CNC router, I would cut the pieces from plywood or another sheet material and assemble it full size.

Design Idea

My design was a C-shaped TV tray. I wanted it to be simple, strong, and able to assemble without screws or glue if possible. The main idea was to use tight-fitting joints so the wood parts would lock together.

The table would have:

Joinery Plan

For the legs, I wanted to use tapered square ends. The idea was that the farther the leg pushed into the slot, the tighter the joint would get. After the leg was fully seated, I planned to cut off or sand down any extra material sticking out past the top surface.

For the bottom C-shaped base, I planned to have the pieces overlap tightly, almost like a C-channel. The ends would be shaped so the legs could slide into the bottom footer and lock the structure together. This would help make the tray stronger without needing a bunch of screws or glue.

This would connect to the extra credit idea of not using fasteners or glue, because the table would rely on the geometry of the parts and friction-fit joints.

Tinkercad Model

Since I could not cut the full-size version, I made a template/model in Tinkercad. This helped me think through the shape, spacing, and basic structure before machining anything.

Tinkercad design link: C-Shaped TV Tray Tinkercad Model

Tinkercad model of C-shaped TV tray

How I Would Mill It

If I had access to a large CNC router, I would export the design files and prepare them for cutting. I would likely use plywood or another sheet material because it is strong, flat, and good for CNC furniture projects.

The machining process would be:

  1. Measure the material thickness.
  2. Update the slot sizes based on the real material thickness.
  3. Create the CNC toolpaths for the top, legs, and bottom base.
  4. Add dogbone corners so square parts can fit into CNC-cut slots.
  5. Cut test joints first to check the fit.
  6. Mill the final parts from the full sheet.
  7. Sand the edges and assemble the tray.

Toolpath Plan

The main cuts would be 2D profile cuts because the pieces are mostly flat sheet parts. I would also use pocket toolpaths for the slots if I wanted the legs to sit part-way into the top or base instead of cutting all the way through.

If I wanted to go further, I could add curved edges or rounded surfaces using three-axis toolpaths. That would make the tray look cleaner and more finished, but the main project could still work with basic 2D CNC cuts.

Problems and Changes

The biggest problem this week was not the design idea. The biggest problem was access to the right machine. Our lab does not have the large wood CNC setup needed to cut a meter-scale furniture piece. Because of that, I had to stop at the design/template stage.

If I do this project later, I would make the design more parametric so I could quickly change the material thickness, slot size, and joint tolerance. That would make it easier to get a clean press-fit assembly.

What I Learned

This week helped me think more about designing for CNC machining. A design that looks simple on screen still needs to account for tool diameter, material thickness, joint tolerance, dogbones, and how the parts will actually assemble.

I also learned that machine access matters a lot. I had an idea that fit the assignment, but without the right CNC router, I could not complete the full cut and assembly. Even though I could not mill the final object, the Tinkercad model helped me plan the structure and think through how I would build it.

Files