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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 toolpath preparation
  • the role of UGS CNC (open-source software) in machine control
  • the importance of machine axes, cutting tools, feeds and speeds
  • and most importantly CNC safety rules

Understanding safety was especially important for me because my final project is also related to safety systems and warning mechanisms.

CNC overview

What is a CNC Milling Machine?

A CNC milling machine (Computer Numerical Control) is a computer-controlled machine used for cutting and shaping materials with high precision.

Instead of manual control, the machine follows instructions from a digital file called G-code.

The machine removes material using a rotating cutting tool called an end mill.

CNC milling machines are commonly used for machining:

  • Wood
  • Plywood
  • MDF
  • Plastics
  • Foam
  • Aluminum
  • Soft metals

Because the machine is digitally controlled, it can create accurate, repeatable, and complex shapes.

CNC machine

How CNC Machining Works

CNC machining follows a digital workflow where a design is transformed into machine instructions.

The general process is:

  1. Create a digital design
  2. Prepare a toolpath
  3. Convert the toolpath into G-code
  4. Send the G-code to the machine
  5. The machine performs the cutting process

This workflow allows precise and repeatable fabrication.

CNC process

CNC Machine Axes

CNC milling machines operate along three main axes.

X Axis

Movement from left to right

Y Axis

Movement from front to back

Z Axis

Movement up and down

These axes allow the machine to control the position of the cutting tool and create different shapes.

CNC axes

CNC Workflow

1. Design (CAD)

The first step is creating a design in CAD software.

This digital model defines the shape, dimensions, and geometry of the object.

CAD design

2. Toolpath Creation (CAM)

The design is imported into CAM software where machining parameters are defined.

Important parameters include:

  • cutting depth
  • feed rate
  • spindle speed
  • tool selection

The software then generates a toolpath, which is the route the tool will follow during cutting.

Toolpath

3. G-code Generation

After defining the toolpath, the CAM software generates G-code.

G-code is the programming language used by CNC machines.
It contains commands that control:

  • tool movement
  • speed
  • position
  • cutting operations

G-code

4. Sending the File to the Machine

The G-code is sent to the CNC machine using control software.

In our lab we learned about UGS CNC (Universal G-code Sender).

UGS CNC

CNC Software

During this week we were introduced to two important software tools used in CNC machining.

This part was very important because it helped us understand the complete connection between design and machine operation.

Aspire 9.5

One of the programs we learned about was Aspire 9.5.

Aspire is used for:

  • preparing CNC designs
  • creating machining strategies
  • generating toolpaths
  • defining cutting parameters

In this software we can configure:

  • material thickness
  • tool type
  • cut depth
  • feed rate
  • spindle speed

Aspire connects the design stage with the machining stage.

Aspire interface

UGS CNC (Open-Source Software)

The second software we studied was UGS CNC (Universal G-code Sender).

UGS CNC is open-source software, which makes it accessible and widely used in CNC environments.

It allows communication between the computer and the CNC machine.

Using UGS we can:

  • send G-code files
  • control machine movement
  • monitor machine status
  • start, pause, or stop the job

Learning Aspire and UGS helped us understand the complete CNC fabrication workflow.

UGS interface

CNC Cutting Tools

CNC machines use different cutting tools called end mills.

Each tool type has a specific purpose.

Flat End Mill

Used for general cutting and flat surfaces.

Ball Nose End Mill

Used for curved surfaces and 3D machining.

V-Bit

Used for engraving and decorative carving.

Compression Bit

Often used for plywood cutting, producing cleaner edges.

Selecting the correct tool is essential for good machining quality.

End mills

Feeds and Speeds

Another important concept in CNC machining is feeds and speeds.

Feed Rate

The speed at which the tool moves through the material.

Spindle Speed

The speed at which the cutting tool rotates.

Incorrect parameters can cause:

  • tool breakage
  • burning material
  • rough surface quality
  • machine vibration

Therefore correct feed and speed settings are essential.

Feeds and speeds

Safety Rules

One of the most important parts of this week was learning CNC safety rules.

⚠️ These safety procedures were explained very clearly and in great detail by our 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.

CNC safety

Personal Protective Equipment

  • Always wear safety glasses
  • Tie long hair back
  • Avoid loose clothing
  • Remove jewelry

Safety glasses

Securing the Material

The material must be fixed securely using:

  • screws
  • clamps
  • hold-down systems

Loose material can move during cutting and become dangerous.

Material clamping

Tool Check

Before starting the machine:

  • check the end mill
  • ensure the tool is not damaged
  • confirm it is tightened properly

Tool check

Emergency Stop

The Emergency Stop button must always be accessible.

If something goes wrong, the machine must be stopped immediately.

Emergency stop

Machine Supervision

The CNC machine must never be left unattended while running.

The operator must monitor the process at all times.

Connection to My Final Project

Safety is a very important concept in my work because my final project is also related to safety systems.

My project focuses on monitoring air quality and activating warning signals when dangerous gas levels are detected.

Because of this, learning about:

  • machine safety
  • risk prevention
  • emergency systems
  • monitoring processes

helped me understand how real safety systems should work in practical environments.

Final project concept

Learning Outcome

During this week I gained knowledge about:

  • CNC milling machines
  • digital fabrication workflow
  • Aspire 9.5 software
  • UGS CNC open-source control software
  • machine axes
  • cutting tools
  • feeds and speeds
  • CNC safety procedures

This experience helped me understand CNC machining not only as a cutting process but as a complete digital manufacturing system that combines design, software, machine control, and safety.