1. The Big Question—What is 3D Printing?

I don’t know if you’ve heard of the term “3D printer,” but I’d be surprised if the majority of readers didn’t at least have an idea about the subject. But I’m going to start from scratch here. I’m going to assume that you know nothing...zero...nada...zilch. I’m going on the assumption that you are reading this book and scratching your head and saying “Nope...no idea.”

However, if you are familiar with 3D printers, you can refer to the Table of Contents and find the chapter that best fits your level of experience. Chapters 2, “Find Yourself a 3D Printer,” and 3, “Assembly Assistance for the Printrbot Simple,” for example, go over one very specific device (and how to build it) that I’ll be using throughout this book. If you already own a 3D printer and/or have already put one together, those chapters can easily be skipped. (But they have some cool sidebars and extra information that you might not want to miss.)

I’m going to start from the beginning and explain everything to you as if we were having a simple conversation. No complex technobabble. No calculus or physics required. And certainly no power tools. Let’s keep this simple, shall we? Because as you’re about to learn, 3D printers are for the masses, not just for the scientists and gizmo-gadgety gurus.

What Is a 3D Printer?

Let’s start with the last term first—printer. Printers come in two varieties. There’s the kind that stands behind a counter in a building full of machines and takes your money when you ask for 150 copies of your son’s graduation invitations or need a large GRAND OPENING banner printed for your new business. I’m not talking about that kind of printer.

I’m speaking of the other kind of printer—the one that you usually see sitting on a desk or being shared by a few dozen office workers. It’s typically bigger than a shoebox and smaller than a car. Many of these kinds of printers can print in color, but not all. They can print a single sheet or the entire 350 pages of your new novel. Figure 1.1 shows a typical printer that spits out paper with ink on it.

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Figure 1.1 A conventional printer, in all its glory.

Printers print on a flat surface. Another way of looking at this is that they print in only two dimensions. Think back to your early math classes and you may remember discussions of dimensions. A one-dimensional object is nothing more than a point in space that can move along a fixed line (like the period that ends this sentence, but without any volume). A point has no height, width, or length. It’s simply a point. Likewise, a two-dimensional object is flat; it has length and width but no height. Figure 1.2 shows some examples of one-dimensional and two-dimensional objects.

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Figure 1.2 Examples of one- and two-dimensional objects.

Two dimensional objects can be drawn in such a way that they look like they have length, width, and height, but they’re still flat. They still exist only in two dimensions.

A 3D printer is a printer that prints in three dimensions. That’s as simple a definition as you’ll ever find. When your inkjet or laser printer prints out a square on a piece of paper, all you have is a two-dimensional square on a flat piece of paper. It lacks height. In fact, an advertisement for a 3D printer might state, “New and improved! Now comes with HEIGHT!”

But if a 3D printer can add that third dimension, then it’s possible to print that square as a cube, as in Figure 1.3.

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Figure 1.3 A basic example of what a 3D printer can accomplish.

And there you have it. A 3D printer can print something with length, width, and height. But I can already hear some of you saying, But no matter how many times I print that square on the same piece of paper, it’s going to stay flat. This is crazy talk!”

And you’re right.

Ink is not very useful for printing solid objects.

Say Hello to Plastic!

Think about this for a moment: You print out a black square on a sheet of paper and then cut it out with some scissors. You then place that black square on a table. Next, you print out another black square, cut it out, and stack it on top of the previous black cube. Do this 500 times. Are you seeing what’s happening to that stack of black squares? Is it starting to look like a cube?


Note

Depending on the thickness of your paper and the size of the square, you might have to print and stack 200, 500, or even 1,000 squares to make it look like a cube. (And I don’t recommend that you actually do this. Save the paper and some trees and just imagine all those stacked squares, and you get the idea.)


What you’re seeing happen here is due to layering. If you could peel the ink off each piece of paper (and have it hold its shape) and then stack all those black squares like the ones in Figure 1.4, you’d (hopefully) have a solid black cube consisting of dozens, or hundreds, or maybe even thousands of layers.

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Figure 1.4 A stack of black squares begins to resemble a black cube.

That’s how a 3D printer creates three-dimensional objects: one layer at a time.

But again, I hear some of you asking, “How exactly does a 3D printer stack ink in layers?” And the answer is simple—3D printers don’t print with ink. Instead, they print using a material that you are already familiar with—plastic.

Look at a two-liter bottle of soda or a kid’s action figure, and you’re looking at a three-dimensional object most likely made of plastic. It’s a rugged material that (usually) holds its shape, is (usually) waterproof, and (usually) won’t melt in the backseat of your car.

Plastic requires a very high temperature to melt, so it’s a favored material for printing three-dimensional objects. And now you’ve learned something else about what makes a 3D printer work—a high temperature. A 3D printer must have a method for heating up plastic until it changes from solid to liquid form.


Note

Not all 3D printers use plastic. You’ll learn about some other types of 3D printers later in the book that use different methods and materials, but for the purposes of this book, I’ll be covering those kinds of printers that melt plastic to a liquid form and deposit (print) that liquid plastic on a surface so that it can cool and harden.


Solid to Liquid

Plastic is somewhat of a vague term because there are many types of plastics. One type might be much harder to twist or break, whereas another might require a higher temperature before it begins to melt. I talk about the various types of plastic used with 3D printers later in the book, but for now I just want you to understand that before a 3D printer can actually “print” a 3D object, it must melt that plastic.

To do this, most 3D printers use plastic filament. Plastic filament is nothing more than a very thin strand of plastic that typically comes in a wrapped bundle like the one shown in Figure 1.5.

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Figure 1.5 A bundle of plastic filament, ready for melting.

Most 3D printers that print in plastic use electricity to heat up a component called the hot end. The hot end melts the plastic, and works with another component called an extruder that pushes the solid plastic into the hot-end. Inside the hot-end, the solid plastic melts and exits the hot-end’s nozzle onto a flat surface. This is called extrusion. This melted plastic quickly cools and solidifies.

Figure 1.6 shows an example of both an extruder and a bit of melted plastic coming out of the bottom as a thin, fine string.

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Figure 1.6 Melted plastic exits the extruder as a thin string of plastic.

Have you ever seen someone write Happy Birthday with icing on top of a birthday cake? The decorator squeezes the icing and moves his or her hands and, hopefully, out comes “Happy Birthday, Mom!” and not “Hopop Diaddap, Nom!”

Hold that thought. A 3D printer works in a similar manner, but without the shaky hands. The cooling plastic is applied to a flat surface, but the plastic is placed on the surface in such a way that when it cools and hardens, its shape has changed from the original loop of plastic filament (seen back in Figure 1.5).

But how does a 3D printer apply the plastic on the flat surface? Most printers don’t have hands, right? Well, it turns out that 3D printers don’t need hands—they have something much better.

A Different Type of Motor

Say the word “motor,” and a lot of people’s eyes glaze over. Motors are strange, magical things to some and intimidating and scary things to others. But motors are important. They get your car from point A to B. They keep your fridge cold (and everything inside). They make certain the light bulbs have power so you can finish reading this book. Motors are everywhere, and they come in all shapes and sizes. And yes, 3D printers have their own versions of motors.

You don’t have to be an electrical engineer to understand the motors found in a typical 3D printer. I promised I wasn’t going to get super-technical on you, so for now I want you to know these five things about the motors found inside a standard 3D printer:

• They are used for movement.

• They can spin clockwise or counterclockwise.

• They can spin at varying speeds.

• They require electricity.

• They are controlled by a computer.

Most 3D printers have four motors. Remember when I told you that a 3D printer could print objects that have length, width, and height? One motor each is used to move the extruder (or the printing surface; more on that in a moment). I’ll explain how this movement occurs later in the book, but for now all you need to know is that the motors spin clockwise or counterclockwise to create movement. (The fourth motor is used by the extruder to feed or push the plastic filament into the hot end so it can be melted.)

What do these motors look like? Take a look at Figure 1.7 and you’ll see a typical 3D printer motor. They don’t all look like this one, but most consist of a hard shell and a shaft that rotates clockwise and counterclockwise.

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Figure 1.7 A motor like this one is typically used in 3D printers.

This type of motor is called a stepper motor, and it has the unique capability to spin (clockwise or counterclockwise) in very tiny increments. This means the shaft can spin not in 1-degree increments, but in fractions of a degree! This is an important concept, and you’ll get some more explanations later in the book. Right now, what you need to take from this discussion on motors is that they do the heavy work by moving items such as the hot end or the plastic filament feed.

Let’s take a quick look at what we now know about 3D printers:

• 3D printers can print three dimensional objects.

• 3D printers use melted plastic to create objects.

• 3D printers use a hot-end to heat up and squeeze out melted plastic.

• 3D printers need motors to control the movement of the hot-end.

• 3D printers use four motors.

Again, 3D printers melt plastic and require motors to move the extruder around as it squeezes out the melted plastic. But how exactly does a 3D printer create objects with recognizable shapes instead of just squirting out one big blob of cooled plastic?

It’s all done by carefully controlling the movement of the extruder along three paths. These paths go by different names, but you can think of them as left/right, forward/backward, and up/down. They also go by shorter names: the X axis, the Y axis, and the Z axis.

3D Objects Require Three Axes

Think back to your early math and recall that all points in space can be described by three coordinates: X, Y, and Z. If you need a refresher, take a look at Figure 1.8, which shows all three axes on an xyz graph.

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Figure 1.8 A point in space has an X coordinate, a Y coordinate, and a Z coordinate.


Note

When talking about X, Y, and Z, use the plural term “axes.” The singular term is “axis.” So, the extruder moves back and forth on the X axis but also can move in any direction using three axes.


You may be wondering just how the xyz graph relates to a 3D printer. It’s now time to show you one example of a 3D printer. Don’t worry if it looks strange or if you can’t figure out how it works; that will soon become apparent. What I want you to focus on are the three directions that the extruder can move. Everything is labeled in Figure 1.9.

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Figure 1.9 A 3D printer’s extruder can move in three directions.

If you’re trying to force the xyz graph from Figure 1.8 to fit the 3D printer shown in Figure 1.9, you might be confused. That’s because Figure 1.9 is showing the 3D printer from the front. Let’s take a look at the 3D printer again, but this time looking down on it from above, as shown in Figure 1.10.

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Figure 1.10 Top view of a 3D printer lets you see the X and Y axes.

Looking at a 3D printer from above, you can now see that when the hot-end moves left or right (when viewed from the front of the 3D printer), it’s actually moving along the X axis. Likewise, when the hot-end moves forward or backward (again, when viewed from the front), the hot-end is moving along the Y axis.

Now go back to Figure 1.9, which shows the 3D printer from the front. Can you see the Z axis now? When the hot-end moves up or down, it’s moving along the Z axis.

Here’s another idea to mull over. If you look at the 3D printer from above, imagine that the X axis can be used to define a two-dimensional object’s length (like a square). The Y axis can be used to define that two-dimensional object’s width. So what do you think the Z axis will be used to define for an object? If you answered “height,” you’d be correct.

A 3D printer’s motors will be used to move the hot-end left, right, back, forward, up, and down. While these movements are occurring, the extruder is constantly pushing in the filament to melt in the hot-end and then coming out the hot-end’s nozzle a thin thread of melted plastic. This melted plastic continues to extrude at a constant rate, almost like ink from a pen as you write your name on a piece of paper. The only difference is that as the plastic cools, it begins to harden. Any melted ink placed on top of an existing (hardened) bit of plastic will simply add to the height of the plastic at that point. And that’s how we get the layering effect that a 3D printer uses to print 3D objects!

Let’s return to that solid black square drawn on a piece of paper. If we use our 3D printer to create that square, what will be required? The extruder needs to move along a path that lets the melted plastic form a square that has the same thickness. Two possible paths it could follow are shown in Figure 1.11.

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Figure 1.11 A single layer of melted plastic in the shape of a square might use one of these paths.

The thickness of the melted plastic is actually thinner than that of a pen (and its ink), but you should get the idea. The hot-end acts like a pen, drawing a path on the flat work surface and creating a square-shaped object. What do you think will happen if the hot-end places another layer of plastic over this first layer? What happens if the hot-end places 10 or 20 or even 50 layers, one on top of each other?

You start to see the beginning of a plastic cube.

A plastic cube might not be much to look at, but if you understand how layers of plastic are combined to create a three-dimensional object, you are well on your way to understanding how a 3D printer can be used to create more advanced objects like those shown in Figure 1.12.

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Figure 1.12 You can use a 3D printer to create objects like these.

A Few Other Items

Most 3D printers have a small circuit board (or controller) that “talks” to the motors and gives them instructions on how to move (how far, how fast, and so on). The motors and the circuit board/controller need electricity to work, so you’ll also find that most 3D printers need a power supply. This often comes directly from a wall outlet, but sometimes it requires an actual power supply box that is attached to the 3D printer in some manner. You’ll see the circuit board later in Chapter 3.

A 3D printer can print 3D objects, but until you tell it what to print and how to print, it’s just a paperweight. For that reason, you’ll be connecting your 3D printer to a computer. More specifically, you’ll be connecting the 3D printer to a computer running specialized software. This software (sometimes a single application, sometimes more than one) is used to create an object and send data to the 3D printer that instructs it on how to print your object using melted plastic.

Don’t let this overwhelm you. I introduce you to all this later in the book and show you how easy it is to do. (And how much fun it can be, too!)

So, let’s summarize what we know:

• 3D printers use motors to move a hot-end around.

• An extruder pushes plastic filament into the hot-end.

• Melted plastic exits the hot-end’s nozzle onto a flat surface.

• Special software provides instructions to the motors that define a path for the hot-end to follow.

• The hot-end follows the path multiple times to create layers.

If you’ve read and understood everything so far, you’re off to a good start! There’s much more to learn; in the next chapter I introduce you to a very simple 3D printer and some variations of other 3D printers. You’ll also read explanations on the benefits and drawbacks of different models, so you can make an informed decision should you choose to purchase a 3D printer kit.