Week07 | Computer Controlled Machining
Overview
This week focused on computer-controlled machining using a CNC router.
The assignment was divided into group work and individual work.
For the group assignment, we completed safety training and evaluated the CNC machine available at the Fab Lab. The goal was to understand how the machine behaves during machining operations and to learn how to prepare and operate it safely and correctly.
For the individual assignment, I designed and manufactured a table using CNC machining.
The workflow included creating the CAD model, preparing the CAM toolpaths, and machining the parts from the available material using the CNC router. After machining, the parts were cleaned, assembled, and tested.
Individual Assignment
CAD Design and CAM Setup
My original plan for the individual assignment was to make a laptop stand. However, after checking the available material size and reconsidering the design, I changed the concept to a small table.
Create a tabletop as a circle with 1066 mm:
Then define the table thickness based on the material thickness available in the Fab Lab. I defined it as a parameter because I would need the same value for the other parts later:
Select the tabletop sketch profile and extrude it using the defined parameter:
Now the tabletop is ready and positioned on the ground level (Z = 0). I moved it to the proper height, for example 800 mm. Click the body and use the shortcut M:
For the legs of the table, create a projected profile on the underside of the tabletop by pressing P and creating the projected geometry:
Create a profile boundary for the legs:
Offset one of the vertical lines:
Create a line to make a profile for one leg:
Offset it:
Offset it again to move the projected line of the tabletop downward:
The leg profile is now complete. I cleaned up the unwanted crossing lines using the Trim tool, and then used Mirror to create the other legs. First, I needed a line to use as the mirror axis:
Again, I used Trim to clean up the leg profile and finish the sketch.
I extruded the part by the thickness of the material in both directions:
This leg is still flat, but I needed interlocking slots. So I created a new sketch on the front face of the leg profile:
The tab slot was created:
Using copy, I created another leg:
I made it a new component and named it leg2, then rotated it 90 degrees:
Now I had two crossed legs. I wanted to create a pocket inside the tabletop using the Combine tool:
Then I created the slot interlock for the legs:
At this point, the table and legs were ready, but I was not fully confident about the stability. So I decided to make the structure stronger.
First, I created the profile for the support part:
Then I extruded it by the material thickness and extended both sides by 75 mm:
Similar to the slot interlock for the legs, I created the same feature for the support piece and the leg:
Then I used a circular pattern to create the remaining supports:
Now I created the interlock cut:
Next, I used Fillet to smooth the sharp corners:
This is the model before adding the Dogbone feature:
I applied dogbones to all 90-degree corners:
CNC Preparation and Setting
Then it was time to move to the Manufacture workspace and prepare the model for the CNC machine:
I created a new manufacturing model, then right-clicked it and modified it. After that, I created components from the bodies.
Then I arranged the bodies. First, I selected all bodies and chose the plane (XY), then checked the length (X-axis) and width (Y-axis) dimensions according to the machine limits:
The automatic arrangement was not optimal, as shown below:
I am not sure why it happened, but I arranged the parts manually because they had to fit the machine dimensions at Oulu Fab Lab (1200 mm × 2400 mm):
This was the manual layout. There was also an issue with the stock box size during setup: the Z-axis height was 12.48 mm, while the model thickness was 11 mm.
How did I solve it? I first tried to fix it manually by moving the parts, but that did not work. Then I deleted the manufacturing setup and started again from zero, and the error disappeared.
Next, I created the 2D Pocket toolpath:
I ran a 2D pocket simulation to check for errors and warnings. There were no errors:
Then I set up the 2D Contour:
And I ran the 2D contour simulation:
There was another issue in the simulation. The last cutting depth in the Z position should have been zero, but in the simulation it appeared as 2.418E-6 mm.
In the contour settings, under the Heights tab, I changed Bottom Height → Model Bottom and set the Offset to 0 mm:
This solved the issue as well. Finally, I generated the G-code and went to the workshop for the cutting process.
Many of the steps are clearly explained in the group work. First, I switched on the machine and started the NcStudio software:
I moved the machine head for Z-calibration:
Z-axis calibration:
I checked and changed the milling bit:
I generated two G-code files in Fusion 360. For cutting, I started with the pocket operation, and before that I ran the simulation again to double-check everything:
The cutting was in progress, and I was taking photos while Antti was checking the machine:
Antti is very patient, precise, and helpful:
Checking the noise level:
The cutting went well without any issues:
It finished:
I cut the tabs with a sharp saw:
Then I smoothed the edges with a wood rasp and started assembling:
I was pleasantly surprised by how accurate the slots were for my first CNC project:
The stiffeners also fit perfectly:
Then I assembled the legs to the tabletop:
I used a hammer to tighten the legs into the tabletop:
I cleaned the area with the central vacuum cleaner:
Although I faced a few challenges in the design and CAM preparation, I was able to produce a functional table:
Reflection
This was a very productive week for me. I learned new features in Fusion 360, including how to design for CNC machining, how to prepare CAM toolpaths, and how to check simulations and settings carefully. I also learned how to import and use libraries in Fusion and how to apply these tools in a practical workflow.
Even though I had already used some design tools before, this assignment helped me improve my understanding of parametric design and manufacturing-oriented CAD. I also gained a better understanding of how small design decisions affect machining, assembly, and final fit.
During the group assignment, I learned about lab and machine safety, how to operate the CNC machine more confidently, and how important it is to protect both the user and the machine. Working with the machine in a real lab environment was especially valuable because it connected the digital model with the physical process.
Overall, this was a very useful experience. It gave me practical knowledge about designing furniture, preparing CNC toolpaths, and assembling parts with good fit and stability. I am happy with the result, especially because this was my first time working with this workflow from start to finish.