Mechanical Engineering for Makers: A Hands-on Guide to Designing and Making Physical Things

Book Preface

When we sat down to write this book, we wanted to be sure that we didn’t create a manual on the use of certain tools or materials, or provide a reference manual for engineering. Rather, we wanted to convey our passion for making that uses techniques many might see as “garage science,” but are actually based on real engineering principles. Do you have to be a mechanical engineer to read this book or understand the topics? Is it full of math and formulae? Is it going to be a textbook cure for insomnia? Not at all! Do you like to tinker, to fiddle, to build, to make? Or, maybe you wish to learn how to tinker, fiddle, build, or make? Then this book is for you. This book is intended for everyone who has a passion to make mechanical things (or make them better), whether you are an engineer or not. Engineering school teaches math and theory about engineering, but rarely provides a hands-on, practical application. That is what this book will provide. It is for all of us backyard- and garage-tinkerers who need just a bit more information to go from a great back-of-a-napkin idea to a glorious finished project.

Within this book, we break down various mechanical engineering concepts to their simplest levels. These concepts are illustrated through hands-on projects, which we strongly encourage you to try on your own. Additionally, we offer Tracking Further sections with more in-depth math and theory. These provide opportunities to dig deeper into mechanical engineering theories and principles, while demonstrating interesting and real-world applications of them. Lastly, watch for small sidebars called Staying on Track. These are little, practical nuggets of wisdom we’ve picked up through the years of making, and include specific tips and tricks we have learned through experience, and in some cases trial-and-error.

Both of us, your authors, are degreed mechanical engineers and life-long makers. We have authored articles on makezine.com and have contributed to other publications, such as Make: magazine and various websites. We have built airplanes, hovercrafts, pneumatic cannons, RC vehicles, simulators, a variety of tanks, and a plethora of other items. We have torn-apart and repurposed more mechanical devices than we can count! We have had great successes as well as failures in our projects, and will continue to make as long as we are able.

We feel that the innate personality of a practical engineer, tinkerer, or maker is driven by curiosity, and a desire to learn about new and different things. This is exactly what we’ve kept in mind while writing this book. We hope you enjoy reading and using this book as much as we enjoyed writing it. — Brian Bunnell and Samer Najia

Why do we build things?
In “The Cathedral and the Bazaar,” Eric Raymond wrote that open-source developers write code and share it openly because they are “scratching their own itch.” They have something in mind that needs to be done. So they just do it, and then share it with others. Some people are skeptical of this idea of “scratching your own itch.” It makes some business people scratch their heads, asking: “Why do it if you’re not being paid?” They don’t understand that there are people of all ages who just build things because that’s what they love to do. Scratching your own itch was also behind the maker movement, which started when lots of people independently began sharing the projects they built based on their own interests and abilities. Makers have many reasons why they build something, but the more interesting question is how they do it. We like to learn from each other how to build things. Ever since I first used the word “maker” intentionally in Make: magazine, I have been fascinated by the variety of projects that makers have worked on in backyards, in garages, and at kitchen tables. These real-world projects use cheap hardware and sensors, often embedding them in physical things to create robots, self-driving cars, wearables, and interactive art. Each year I can discover new and surprising projects at Maker Faires around the world.

In the magazine, makers have shared the how-to procedures for their projects, so that others might learn from them and build that project, or others like it. Makers have talked about the tools they use and the different parts that they source. As computer-assisted design (CAD) have become easier to use, and new machines such as 3D printers have made it possible for individuals to do manufacturing in small lots. Makers were the first to realize that a prototyping revolution was taking place, where going from idea to prototype was faster and cheaper and more accessible than ever. If there is an essential quality for a maker, it is curiosity. Makers are interested in figuring out how things work. They are good learners, largely because they are motivated to do something with what they learn. The best makers expand their practical skills but also deepen their conceptual knowledge. However, as projects become more complex and ambitious, the learning curve can be more challenging. Some people fall off. Others do it as a profession.

This book, Mechanical Engineering for Makers, is intended to help makers continue continue their journey to do more by exploring the basics of mechanical engineering. Makers can benefit from understanding how mechanical engineers think about machines and systems. Nonetheless, the goal is to apply this thinking in a typical maker project. The authors, Brian and Samer, are makers who understand why people work on projects in a garage for fun. They are also mechanical engineers who have knowledge and experience gained from the university and the workplace. By intention, this book is not a textbook. Nor is it a replacement for a course of study in mechanical engineering. It’s really a crossover, a new bridge between making and mechanical engineering, between amateur and professional. You can go back and forth as many times as you want, and bring things of value with you. It won’t make you an expert. But it will generate insights and reward your curiosity. You will learn new ways to approach problems. Ideally, this book may introduce young makers to the prospects of an engineering discipline and a fulfilling career. After all, these authors were once kids who made things.

With detailed procedures, images, and diagrams, as well as a little math, the book is accessible to non-technical readers interested in learning more about how to build things. Samer and Brian explain the theory in clear language and show the practice through a wide range of projects. I hope it helps you have more fun and be more satisfied with scratching your own itch, whether at work or play. May you tackle more interesting projects!

— Dale Dougherty
Founder of Make: magazine and Maker Faire