A Tinkerer's Guide to CNC Basics: Master the fundamentals of CNC machining, G-Code, 2D Laser machining and fabrication techniques

BIRMINGHAM—MUMBAI

A Tinkerer’s Guide to CNC Basics

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First published: February 2024

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ISBN 978-1-80324-749-6

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To my wife, Sanja, for lovingly and patiently putting up with my projects and incessant desire to build things. To my children, Hanna and Jordan, for inspiring my creativity.

– Samer Najia

Contributors

About the author

Samer Najia has always enjoyed building things and often has multiple projects in the air. While by day he is in the IT field, at all other times he is often putting bits of things together in the garage or on his desk. When the sky beckons, Samer likes to fly and work on airplanes.

About the reviewer

Atif Tajul, born in Kuala Lumpur, Malaysia, is a mechanical engineer who graduated from the University of Southampton, United Kingdom. He indulges himself in anything hands-on and enjoys tinkering. He is a very practical person when solving problems and providing solutions. He has experience of working on cars as an apprentice mechanic, and the skills and knowledge he gains from that are used for the benefit of his family. Atif 3D prints personal designs with his own machine in the pursuit of becoming a master at prototyping and fabrication. He keeps himself in shape by playing football as he is a massive fan of the sport.

Table of Contents

Preface

1

The What and Why of CNC

Branches of CNC machining

Differing approaches to motion in CNC machines

How CNC works and when to use it

What is G-code?

Safety considerations for CNC and lasers

Summary

2

Setting Up and Configuring the 3018 CNC Machine

Technical requirements

Anatomy of a CNC machine

Making the build-versus-buy decision

Buying a pre-built unit

Building your own unit

Configuring, calibrating, and testing your CNC machine

Step calibration

Firmware flashing software

G-code sender software

Running your first test cut

Summary

3

Understanding Material Properties before Making the First Cut

Cutting hardwoods, plywood, and balsa

Cutting foam and composites

Cutting plastics and PVC

Cutting aluminum and other soft metals

Selecting the right end mill

Summary

4

Making the First Cut

Securing the workpiece

Selecting test patterns

Configuration settings

End-mill diameter

RPM or spindle control and feed rate

Cut depth and multiple passes

Different settings for different operations

Summary

5

Full CNC Workflow with Different Materials

Technical requirements

Getting to G-Code from a drawing

Cutting softwoods such as balsa and light plywood

Cutting hardwood

Cutting and engraving soft metals

Working with foam

Engraving your workpiece and setting depths

Summary

6

Upgrading Your CNC Machine

Installing end-stops

Emergency stop switch

Installing a Z-probe

Adding a rotary axis

Plotters and drag knives

Summary

7

Enclosures

Panels, cleaning, and access

Removable and non-integral enclosures

Integrated and permanent enclosures

Build versus buy, materials, and designs

Summary

8

Project: Building a CNC Laser Cutter and a Plotter

Laser cutter/engraver

Endstops and electronics

Plotter

Summary

9

Project: Building Your Own 4th Axis

Design is the starting point

Fabrication

The final assembly

Installation and settings

Summary

10

Project: Adding a Laser to the 3018

Selecting a suitable laser toolhead

Mounting adjacent to the spindle

Mounting in place of the spindle

Laser-cutting software

Laser head installation examples

Summary

11

Building a More Capable CNC Machine

Building a bigger 3018

Standardizing and simplifying your structure

Eliminating the moving table

Use multiple motors

An all-metal Z axis

A more robust controller board

Scaling up

Summary

12

Future Projects and Going Bigger and Better

The ShapeOKO

The OX

Hot wire foam cutters

CNC lathe

A fifth axis

Summary

Index

Other Books You May Enjoy

Preface

A Tinkerer’s Guide to CNC Basics will suit anyone who enjoys shop work and tinkering through the process of automating the fabrication of parts of various materials, including cutting and engraving with milling machines and lasers. If you have a desire to make things out of wood, metal, plastic, foam, fiberglass, or other materials, and maybe have to make several parts repeatedly, this book is for you. If you need to prototype your designs and want to be able to do so fast so you don’t have to hand fabricate everything and learn how to leverage Computer-Aided Design (CAD), you will benefit from this book.

The book starts with an overview of what CNC is and progresses toward acquiring, building, and customizing a commonly used CNC machine before delving into various projects. These projects include upgrades to this machine, building larger and more complex machines, and fabricating parts for specific applications. You will learn how to operate and service a desktop CNC machine, use CAD to design or modify parts that your machine can then fabricate, and finally learn how to scale up your efforts with bigger and more complex systems.

By the time you are finished with this book, you will know how to fabricate using a basic CNC machine, cut with a laser, use a fourth axis to cut parts as they rotate on your work table, and operate multiple software applications to achieve your desired outcomes. You will also become familiar with a number of techniques to transfer drawings from paper to electronic formats suitable for fabrication by your CNC mill.

Who this book is for

Anyone who enjoys working in their home shop or garage or likes to tinker and build things from scratch out of many materials will enjoy this book. Tinkerers will grow their skills and add automation to their repertoire of tools to fabricate just about anything.

What this book covers

Chapter 1, The What and Why of CNC: This chapter introduces CNC, discusses the mechanics of how it works, and provides some initial considerations for safety.

Chapter 2, Setting Up and Configuring the 3018 CNC Machine: This chapter’s focus is on the build-or-buy decision and getting your first CNC machine up and running.

Chapter 3, Understanding Material Properties before Making the First Cut: Here, we take a look at what is needed for various materials as far as the CNC machine is concerned, such as how to select an endmill for a particular application.

Chapter 4, Making the First Cut: With this chapter, we’ll put the 3018 to work and start cutting materials.

Chapter 5, Full CNC Workflow with Different Materials: Building on the previous chapter, we begin looking at how to go from design to finished product, including the transfer of paper drawings to an electronic format suitable for subsequent processing with our 3018 machines.

Chapter 6, Upgrading Your CNC Machine: We’ll add components to the machine we have to be more precise, start with a discussion on a fourth axis, and add the ability for our machine to become a plotter and a drag knife.

Chapter 7, Enclosures: CNC machines produce debris, and if using a laser, there could be fumes that might need ventilation. This chapter discusses some simple enclosures that can be built to keep your work area neat.

Chapter 8, Project: Building a CNC Laser Cutter and Plotter: Taking everything we have learned so far, we’ll build limited-purpose CNC machines: one to generate and scale drawings and another to cut using a laser.

Chapter 9, Project: Building Your Own 4th Axis: In this chapter, we build on Chapter 6 and build a fourth axis add-on using our 3018 and some off-the-shelf parts.

Chapter 10, Adding a Laser to the 3018: We’ll add a laser toolhead to our original desktop CNC mill to make it a 2-in-1 machine.

Chapter 11, Building a More Capable CNC Machine: Once we outgrow the 3018 machine, we will want something bigger and stronger with a larger workspace. This chapter steps through the process of scaling up.

Chapter 12, Future Projects and Going Bigger and Better: We’ll look at even bigger machines for our shop including stepping out of the hobbyist arena and seeing what industrial CNC machines can do. We also have a quick look at five-axis CNC machines.

To get the most out of this book

You will need some basic tools to assemble your machines, including drills, drill bits, screwdrivers, hex keys, rulers, and tape measures, some scrap material to use when test cutting with your CNC machine, and a suitable work area. Safety gear is also highly recommended, including eye protection, and when using the laser, special eye protection is mandatory.

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1

The What and Why of CNC

Computer numerical control (CNC) is a software-based method of moving tools and machinery. This method has traditionally been under the purview of factories and manufacturing facilities and well beyond the reach of a garage tinkerer. CNC machines have arms and carriages that can hold mills, grinders, lasers, and other cutting tools that move in multiple axes to shape an object via preprogrammed movement commands.

Our objective in this chapter is to provide a basic understanding of CNC from a hobbyist’s/tinkerer’s perspective as we prepare to take a deep dive into obtaining, operating, and customizing our own machine.

In this chapter, we will cover the following topics:

Branches of CNC machining

Differing approaches to motion in CNC machines

How CNC works and when to use it

A brief overview of G-code, the commands used to operate a CNC machine

Safety considerations for CNC and lasers

Branches of CNC machining

CNC manufacturing can be traced back to the 1940s, when the first numerical control (NC) machines started to appear (https://en.wikipedia.org/wiki/History_of_numerical_control), and methods to automate handcrafted fabrication can be traced to three centuries ago. I’m sure you’ve seen videos of these machines perhaps fabricating the engine block for a car or cutting and shaping sheet metal. For all intents and purposes, a CNC machine is a type of robot. It takes stock material (a sheet of wood, a block of aluminum) and turns it into a product ready to be assembled or finished very quickly, very accurately, and, most importantly, repeatedly. CNC machining made fabrication at scale possible.

With the advent of desktop computing, more commonly accessible materials, and smaller, more powerful components, it also became possible to bring CNC machining to the home workshop. Now, anyone with a good guide can put together a robust desk or bench-top CNC machine and get to cutting, engraving, and milling themselves. Such machining is not limited to metal, wood, foam, and other materials; there are multiple branches of CNC machining:

PCB milling: Where holes are drilled in the right places and the circuit board is cut and shaped for whatever they are going into.

Rotary engraving: Where the movement is around an axis instead of along it. Imagine engraving a bottle, glass, or vase.

Multi-axis machining: Where the machine does not just operate in X, Y, and Z, but also rotates the object being worked on to shape all of its sides (this is a typical use case for machining a car’s engine block). For an example of this, look at this video: https://www.youtube.com/watch?v=tO6AGOjBoGo.

Figure 1.1 – Example of the three