Week 07 — Computer Controlled Machining (CNC)¶
Overview¶
This week was focused on Computer Controlled Machining (CNC) and understanding how digital fabrication machines can precisely cut materials using computer-generated instructions.
During this week I learned:
- what a CNC milling machine is
- how CNC machining works
- the complete CNC workflow
- the role of Aspire 9.5 in generating toolpaths
- the role of UGS CNC (open-source software) for machine communication
- the importance of machine axes, cutting tools, feeds and speeds
- and most importantly the safety rules of CNC machines
Understanding safety was especially important for me because my final project is also related to safety systems.
Figure 1 — CNC milling machine in Fab Lab Dilijan.
What is a CNC Milling Machine¶
A CNC milling machine (Computer Numerical Control) is a computer-controlled fabrication machine used for cutting and shaping materials with high precision.
Instead of manual control, the machine follows instructions written in G-code, which is the language used to control CNC machines.
The machine removes material using a rotating cutting tool called an end mill.
CNC milling machines can process materials such as:
- Wood
- Plywood
- MDF
- Plastics
- Foam
- Aluminum
Because CNC machines are digitally controlled, they allow accurate and repeatable manufacturing.
Figure 2 — CNC milling machine.
CNC Machine Axes¶
CNC milling machines usually operate along three main axes.
X Axis — movement left to right
Y Axis — movement front to back
Z Axis — vertical movement up and down
These axes allow the machine to control the position of the cutting tool and create complex shapes.
Figure 3 — CNC machine axis diagram.
CNC Workflow¶
The CNC machining process follows several stages:
FreeCAD → Aspire 9.5 → G-code → UGS CNC → CNC Milling
1. CAD Design¶
The first step is creating the digital design using CAD software.
Figure 4 — Chair design created in FreeCAD.
2. CAM Toolpath¶
The design is imported into CAM software where toolpaths are generated.
Important parameters include:
- cutting depth
- feed rate
- spindle speed
- tool selection
Figure 5 — Toolpath creation in Aspire.
3. G-code Generation¶
After the toolpath is defined, the CAM software generates G-code instructions.
Figure 6 — Example of generated G-code.
4. Sending File to CNC¶
The G-code file is sent to the CNC machine using UGS CNC.
Figure 7 — UGS CNC interface.
CNC Software¶
During this week we learned about two important programs.
Aspire 9.5¶
Aspire 9.5 is used to prepare machining operations and generate toolpaths.
Using Aspire we can:
- define material thickness
- select the cutting tool
- define feed rate and spindle speed
- generate toolpaths
- export G-code
Figure 8 — Aspire 9.5 interface.
UGS CNC (Open-Source Software)¶
UGS CNC (Universal G-code Sender) is an open-source program used to communicate with CNC machines.
Using UGS we can:
- send G-code to the machine
- control axis movement
- monitor the job
- start or stop machining
Figure 9 — UGS CNC control panel.
CNC Cutting Tools¶
CNC machines use different cutting tools called end mills.
Flat End Mill¶
Used for flat surfaces and general cutting.
Ball Nose End Mill¶
Used for curved surfaces and 3D machining.
V-Bit¶
Used for engraving.
Compression Bit¶
Used for cutting plywood with clean edges.
Figure 10 — Examples of CNC cutting tools.
Feeds and Speeds¶
Two important machining parameters are:
Feed Rate — speed at which the tool moves through the material.
Spindle Speed — speed of tool rotation.
Incorrect values may cause:
- tool breakage
- burned material
- poor surface quality
Figure 11 — Feed and speed diagram.
Safety Rules¶
⚠️ These safety rules were clearly explained by the instructors at Fab Lab Dilijan during the Fab Academy program.
Because CNC machines operate with high-speed rotating tools and powerful motors, following safety rules is essential.
Figure 12 — CNC safety rules.
Personal Protective Equipment¶
- wear safety glasses
- tie long hair
- avoid loose clothing
- remove jewelry
Figure 13 — Personal protective equipment.
Material Fixing¶
Material must be firmly fixed using clamps or screws.
Figure 14 — Fixing material on the CNC bed.
Tool Check¶
Before machining the tool must be checked.
Figure 15 — End mill installation.
Emergency Stop¶
Always know the location of the Emergency Stop button.
Figure 16 — Emergency stop button.
Individual Assignment¶
After learning about CNC machining and safety procedures, I started my individual assignment.
The design was created in FreeCAD.
My goal was to design a chair assembled using press-fit joints.
This design allows assembly without screws or glue, using joints that match the thickness of the material.
Figure 17 — Chair design in FreeCAD.
G-code Generation¶
After finishing the model in FreeCAD, I imported the design into Aspire 9.5.
In Aspire I:
- defined material thickness
- selected the cutting tool
- created toolpaths
- generated the G-code
Figure 18 — Toolpath generation.
CNC Machine Setup¶
Before starting the machining process the machine had to be prepared.
Steps included:
- installing the cutting tool
- preparing the machine bed
- setting X, Y, Z origin
Figure 19 — CNC machine setup.
Milling Process¶
Once the setup was completed, the G-code was loaded into UGS CNC and the machining process began.
Figure 20 — CNC milling process.
Final Result¶
After machining, the chair parts were ready.
The parts were designed using press-fit joints, allowing them to be assembled without screws or glue.
Figure 21 — Final CNC cut parts.
Learning Outcome¶
During this week I learned:
- CNC machine fundamentals
- digital fabrication workflow
- Aspire 9.5 toolpath generation
- UGS CNC machine control
- cutting tools and machining parameters
- CNC safety procedures
This week helped me understand CNC machining as a complete digital fabrication process connecting design, software, machine control, and physical manufacturing.