Making Things Move: DIY Mechanisms for Inventors, Hobbyists, and Artists - Dustyn Roberts (2010)

Introduction

What This Book Is

In a conversation I had with Bre Pettis, one of the creators of the CupCake CNC at MakerBot Industries (www.makerbot.com), I asked if any of the creators were mechanical engineers by training. He replied “No, if we were, it would have been impossible.” The CupCake CNC is a miniature 3D printer that uses computer models to create real 3D objects about the size of a cupcake out of melted plastic. The MakerBot team members were able to build it from available materials with the tools they had on hand. A trained engineer would have known how difficult this project would be and might not have attempted it without the proper resources or funding, but the MakerBot team members didn’t have the experience to know what they were getting themselves into. They just kept their goal in mind and figured out a way. This book is written for anyone who wants to build things that move but has little or no formal engineering training. In fact, as Bre said, not having engineering training may help you.

In this book, you will learn how to successfully build moving mechanisms through nontechnical explanations, examples, and do-it-yourself (DIY) projects. Maybe you’re a sculptor who wants a piece of art to come alive, a computer scientist who wants to explore mechanics, or a product designer who wants to add function to complement the form of your product. Maybe you’ve built projects in the past, but they fell apart easily. Or maybe you didn’t grow up making things move but want to learn. The students in the class I teach at New York University’s (NYU’s) Interactive Telecommunications Program (ITP) in the Tisch School of the Arts have been all of these things, and they gave me the inspiration to write this book.

The class is called Mechanisms and Things That Move, and was created to fill a gap in the program between what students were already learning how to do (basic electronics, interaction design, and networked objects) and what they wanted to make (baby strollers that autonomously climb stairs, wooden mechanical toys, and stationary bikes that power televisions). The objective is to start with their seemingly impossible project concepts, inject some basic engineering know-how, and end up surprisingly close to the original concept. You can see these projects and more on the class site at http:// itp.nyu.edu/mechanisms. I realized in the first year of teaching this class that the practical experience I had gained from engineering design work could be applicable to a completely different audience of nonengineers. I was told by one student, “Your class gave me a whole new world” and by another, “It’s unbelievably satisfying to design and build something that works.” This book is designed to bring this level of satisfaction to all the people who want to learn about mechanisms but don’t know where to start.

There is little purpose to building circuits for an electromechanical project if the mechanism to be controlled is too weak to handle the task. You can protect projects from costly overdesign with a basic knowledge of mechanics and materials. To address these ideas, I’ll cover a breadth of topics, ranging from how to attach couplers and shafts to motors to converting between rotary and linear motion. You’ll be guided through each chapter with photographs, drawings, schematics, and images of 3D models of the components and systems involved in each project. All the illustrations were drawn by an actual illustrator (and nonengineer) in order to minimize the intimidation factor of difficult-sounding concepts and graphs. The resulting interpretation of the concepts is in a playful style designed to be eye catching and friendly.

I emphasize using off-the-shelf components whenever possible, and most projects will also use readily available metals, plastics, wood, and cardboard, as well as accessible fabrication techniques. Simple projects are placed throughout the book to engage you in applying the material in the chapter at hand. At the end of the book, you’ll find more complex projects that incorporate material from multiple chapters.

I guarantee that you will gain a general understanding of mechanisms and save time, money, and frustration by avoiding mechanical design mistakes that lead to failure. Anyone can become a mechanism maker—even if you’ve never set foot in a machine shop.

What This Book Isn’t

This book is not an engineering textbook. It assumes no prerequisite knowledge of electronics or robotics, and you do not need to know what a microcontroller is or how to program one to get the most out of this book. I don’t assume you’ve grown up with a metal shop in your garage, know what a lathe is, or can estimate motor torque by looking at a rotating shaft.

Each chapter could be expanded to a book of its own, and there are many other places to look for detailed technical explanations. This book is about getting things made, and it includes the necessary information for you to do just that. The small amount of theory and background presented will help you understand how mechanisms work, so you can concoct and manipulate your own creations. If these sections get too heavy for you, or you already know the background, skip right to the hands-on stuff.

How to Use This Book

As the White Rabbit was told by the King in Alice’s Adventures in Wonderland, “Begin at the beginning, and go on till you come to the end: then stop.” If you really have no background in making things, this is probably the best way to approach the book. You would only get frustrated when you read about estimating torque in Chapter 6 if you had not read Chapter 4’s discussion of torque and don’t know what it is. Do the small projects to start getting your hands dirty and used to making things. The chapters are organized in a way that builds up knowledge of all the parts that go into building things that move, so when you get to the end of the book, you will have all the tools in your tool belt and be ready to conquer the final projects in Chapter 10.

Each project in the book has two sections: shopping list and recipe. I’ve heard that baking is more of a science, and cooking is more of an art. Making things move is a bit like baking in the beginning. You want to make sure you measure every ingredient just right, follow every step, and do everything by the book. But once you get used to making things move, it becomes more like cooking. After you get the basic recipes down, you can start adding your own ingredients and experimenting.

You can also use this book as a reference manual, especially if you have theoretical knowledge of how things work but want a practical guide to making things move. This latter scenario is where I was after my undergraduate education in engineering. I could figure out the torque or force I needed to make things move, but couldn’t tell you how to choose a motor or attach something to its shaft. They don’t teach that kind of stuff in school (at least not where I went), so you need to learn it through experience. I hope this book will help you start higher on the practical learning curve than I did.

Your Ideas Are Your Biggest Assets

Although very little prior knowledge of mechanisms is assumed in this book, anything you do know will help you, and I do mean anything.

The most important thing you bring to the table is an idea. Some of the most amazing projects I’ve seen have come from people with no prior experience in hands-on projects, and certainly no engineering degree. If you’re a passionate musician who has an idea for a guitar that plays itself, you are more likely to end up with a great project than if you’re an engineer who thinks you know how a guitar works but have never picked one up. This book will give you the tools to make your passions into projects and your concepts into realities. The tools are here, along with examples of how to use them, but the ideas on how to apply them come from you.

I don’t claim to be an artist. My right brain is not nearly as developed as most of the students and designers I’ve had the pleasure of working with. However, I do claim to know how to talk nonengineers through the process of creating things that move. You could use this book as a light read to kill time on a Saturday night, but what I’m banking on is that this book will give you the tools and techniques you need to take that concept for a human-powered smoothie blender out of your head and into reality.

The book includes plenty of projects that you can build, but the applications of the concepts and skills are limited only by your imagination. Mechanisms can seem a little scary at first, but once you break down a complicated project into its elements, you’ll learn that it’s not so daunting after all. This book will enable you. And the more you learn, the more inspiration you will have for future projects.

What You Need to Know

Although prior engineering and fabrication expertise is not required, you do need to know a few things to get the most out of this book. One of the most important is knowledge of how to use the Internet. There are at least three reasons for this.

• When it comes to mechanisms and all things related, we are standing on the shoulders of giants. From the Instructables website (www.instructables.com) to Leonardo Da Vinci’s first mechanical sketches, a lot of inspiration can be found online to help form ideas for projects and learn from similar ones. The goal of this book is to get projects done, not to learn everything there is to know about a topic before getting started. Are you trying to convert rotary motion to linear motion? Guess what—you’re not the first person to do that. Take advantage of the basics explained in this book, and the dozens of websites devoted to examples of converting rotary to linear motion, to inspire the mechanism you need to realize your idea. Borrow the idea, and then customize it to make it your own, and always give credit where credit is due. As Aiden Lawrence Onn and Gary Alexander say in their book Cabaret Mechanical Movement: Understanding Movement and Making Automata (London: G&B Litho Limited, 1998), “If you want to make things move, be sure to spend some time studying how other things move.”

• Making things requires parts and tools. You will most likely need to order some of these things online. Although you can do a lot with cardboard boxes and straws, you may not have a local big box store that sells DC gearhead motors for your Not Lazy Susan (Project 10-1 in Chapter 10). Luckily, you can order parts and tools online, no matter where you are. You can also get better deals on most things—from hand drills to alligator clips—than you can at your local hardware store. Resources are listed for each project, but a few I will refer to often are McMaster-Carr (www.mcmaster.com), SparkFun (www.sparkfun.com), and All Electronics (www.allelectronics.com).

• This book has a companion website: www.makingthingsmove.com. Color photographs and videos that cannot be included in the book will be posted here. You will also find a blog and other resources. By purchasing this book, you have become part of a maker subculture that is bigger than you may know. The makingthingsmove.com website will help you connect with those who share similar interests. Links to digital files to download, make, and buy will be posted there, or you can search for “dustynrobots” on Thingiverse (www.thingiverse.com), Ponoko (www.ponko.com), or Shapeways (www.shapeways.com) for a full listing of everything I have posted.

Along with knowing how to use the Internet, I also expect you to have a working vocabulary of geometry, trigonometry, and basic algebra skills. If you can solve for the ? in the equation 2 × ? = 6, and know what sine, cosine, and tangent mean, relax—that’s about as complicated as we’ll get in this book. You need to know what words like diameter, circumference, tangent, and perpendicular mean. If any of your knowledge in this area is a little rusty, do a quick search online to review.

What You Need to Have

Each project in the book has a shopping list of parts and tools, so you can pick and choose what you need. However, if you want to get a head start, here are some common tools that will serve you well (see Figure 1):

FIGURE 1 Basic tools and supplies to get you started

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1. Hand drill You will use this for drilling holes in wood and thin metal for screws and dowels during project construction. I prefer the cordless, rechargeable kind like the Dewalt model pictured, but any drill will do. Make sure it can hold small drill bits (down to 1/16 in diameter). A Dremel rotary tool will also do the trick for most small jobs, and can be used for cutting and sanding small parts as well.

2. Multimeter You will use this any time you’re working with electricity to check if your battery is dead and if your circuit is hooked up correctly. Make sure the multimeter you get measures voltage, resistance, amperage, and continuity. Do yourself a favor and get a model that is autoranging. This means that you don’t need to estimate the thing you’re measuring before you measure it to choose the correct setting. Autoranging will be a little more expensive, but it will save you time and frustration if you’re not well versed in electronics. Auto-off is a nice battery-saving feature. The one pictured in Figure 1 is SparkFun’s TOL-08657. It’s autoranging and can measure higher current than cheaper models, so it will come in handy when working with motors. A basic soldering iron (RadioShack 64-280 pictured) and wire stripper (SparkFun TOL-08696) will help when you start working with circuits.

3. Measuring tools A tape measure for large things, a metal ruler for small things and to use as a cutting edge, and a caliper for even smaller things. I recommend a digital caliper for ease of use (SparkFun TOL-00067).

4. Screwdrivers Phillips and flat head styles. Having a few different sizes on hand is a good idea. Jameco Electronics (www.jameco.com) sells a handy two-sided miniature tool for about $2 (part number 127271). A larger, multipurpose option is the Craftsman 4-in-1 (model 41161). Cheaper ones will be made of soft metal, and the tips will get bent out of shape easily, so go for a step above the bargain-basement models.

5. Multitool More commonly referred to as a Swiss Army Knife or Leatherman, multitool is the general name. It is handy to have around and may save you from buying a lot of separate tools to do little jobs. Multitools come in all different shapes, sizes, and prices, but I recommend getting one that has at least screwdriver tips, scissors, a file, a knife, and a saw blade. I’ve had a Leatherman Blast for years, and at a cost of around $45, it has earned its spot in my toolbox many times over. Check here for Leatherman brand models: www.leatherman.com/multi-tools. The Maker Shed (www.makershed.com) sells a few laser-etched models, aptly named “warranty voider” and “bomb defuser.” For Swiss Army brand tools, check www.swissarmy.com/multitools under the Do-It-Yourself category. For particularly frustrating projects, look for a multitool with a corkscrew and/or bottle opener.

6. Duct tape and WD-40 “If it moves and it shouldn’t, use duct tape; if doesn’t move and it should, use WD-40.” I’m not sure where I first heard this, but it may have been on a page-a-day calendar my boss had on his desk at my first engineering internship called “365 Days of Duct Tape.” Most readers will be familiar with the standard wide silver duct tape you can use for just about anything. WD-40 is also handy to use on everything from squeaky hinges to lubricating gears and other moving parts.

The most important thing to have is not a tool. It is a commitment to safety. Don’t drill a hole to mount your motor without wearing safety glasses, and don’t drill into a piece of wood right on top of your kitchen table. You are likely to end up with sawdust in your eye and a hole to cover up with a strategically placed placemat. Use gloves when handling sharp things or rough edges that might cut you or cause splinters. I will point out safety concerns in each specific project, but get in the habit of thinking through an action before you do it to identify safety hazards and eliminate them. Although cuts and scrapes heal, it’s very hard to grow back your sense of hearing after too many hours listening to a loud drill, or to regain your sense of sight after the Dremel cutting wheel flies off in an inconvenient direction. At the very least, have a pair of safety glasses and earplugs around and use them. Safety precautions should always be the first step of any project you do.