An Introduction to 3D Printing

Travis Ripley

3D printing is also known as Additive Manufacturing. It is the process of

producing three-dimensional objects, in which successive layers of varied

material are extruded under computer-controlled equipment that is fed

information from 3D models. These models are derived from a data source that

processes the information into machine language.

What is 3D Printing?

The technology allows you to produce rapid prototypes - excellent for personal

and professional use alike. Ideas can go from conception to reality in a fraction

of the time that they would do using traditional methods of manufacture.

If youre dealing with clients, they will undoubtedly feel more reassured if they

have tangible and solid objects throughout the design process, and therefore

they are more likely to trust you as a result, allowing you to complete jobs more

smoothly and with shorter turnaround times. As 3D printing allows you to

provide physical updates on your project progress, it means you can address

design amendments quickly and easily, in order to minimise flaws and failures

further down the line.

The potential application of 3D printing techniques across a huge variety

of sectors is endless. From toys to healthcare, 3D printing can provide quick

solutions and make previous practice better and simpler.

The technology has also made it easy to produce obsolete as well as new

items, great for repairing damaged objects by printing parts that are no longer

manufactured.

What are the Benefits of 3D Printing?

Unfortunately you cant simply just start using a 3D printer - you need to

have some basic understanding of the manufacturing process, such as an

understanding that layers of material need to be successfully laid down in order

to move on to the next stage in the process. This can be the most difficult part

for beginners, who are eager to engage in this new world.

What are the Obstacles to 3D Printing?

The plastic extrusion technology that is now becoming slowly more popular

in 3D printing is known as Fused Deposition Modeling (FDM). This process

was developed in the early 1990s for the application of job production,

mass production, rapid prototyping, product development, and distributed

manufacturing. The principle of FDM is that material is laid down in layers. There

are many other processes such as Selective Heat Sintering (SHS), Selective Laser

Sintering (SLS), Stereolithography (SLA), and Plaster-Based 3D Printing (PP) to

name a few. I will keep it simple here and just go over the FDM process, as most

of the printers at the hobbyist level use this process.

The FDM process has significantly affected roles within the production and

manufacturing industries. As it is able to wear multiple hats as an engineer,

designer and operator, it has made the technology more affordable to an array

of industrial fields.

In contrast, CNC Machining, which is a Subtractive Manufacturing process,

has been incorporated naturally to work together in this development. The

influence of this technology in the industrial and manufacturing industries,

Types of 3D Printing Technology

such as automation, has created exposure to new methods of production at

exponential rates.

The FDM Process

The FDM process can be done with a multitude of materials; the two most popular

options at this time are PLA (Polylactic acid) and ABS (Acrylonitrile butadiene

styrene). Both PLA and ABS have pros and cons, depending upon your model

structure. The future use of the print and client requests and understanding the

fundamental differences between the two can help you determine your choice

of one over the other, or in the case of owning a printer with two extruders, how

they can be combined. In some cases, PVA (Polyvinyl Acetate) is also used as

support material (in the case of two extruders) unlike PLA or ABS, which if used

as a support material will require cleanup when finishing a print. PVA is water

soluble, so you can soak your print in warm water and the support structures

will dissolve away.

PLA (Polylactic Acid) is a strong biodegradable plastic that is derived from

renewable resources: cornstarch and sugarcane. It is more resistant to UV rays

than ABS (so you will not see fading with your prints). Also, it sticks better than

any other material to the surface of your hotplate (minimal warping), which is a

huge advantage. It prints at -180o C, and it can create an ooze, and if your nozzle

is loaded it will drip, which also means that leaving a print in your car on a hot

day may cause damage.

ABS (Acrylonitrile butadiene styrene) is stronger than PLA, but is non-

biodegradable; it is a synthetic monomer produced from propylene and

ammonia. This means it has more rigidity than PLA, but is also more flexible.

It is a colorfast material (which means it will hold its color for years). It prints at

-220oC, and is amorphous and therefore has no true melting point, so a heated

bed is needed as warping can and will occur (usually because the bed is not hot

enoughat least 80oC or the Z axis is not calibrated correctly).

There are literally dozens of 3D printer designs available on the market. The

designs range from high-end printers that can print plastic with embedded

carbon fiber, to popular designs from MakerBot and DIY kits on eBay.

For the home-use and hobbyist market, the 3D printers produced by the open

source/open hardware initiative can be stemmed directly or indirectly from the

Reprap.org project, which is a free to low-cost desktop 3D printer that is self-

replicating, so the parts for the machine can be fabricated by the machine itself.

Most people who build RepRap printers start with a kit and then assemble the

printer themselves. Once you assemble your printer you can make changes and

upgrades to the machine by printing yourself new parts. RepRap is now more

of a philosophy and community than any specific printer. By getting involved

in this community you are benefiting everyone by spreading the spark that

will continue to create new developments in manufacturing and consumer

technology.

For the hobbyist maker, there are a few 3D printer options to consider. Depending

upon your skill level, your needs, budget and commitments, there is a printer

out there for you.

Choosing Your Printer

The least expensive, smallest, and most straightforward printer available on

the market is Printrbot Simple Makers 3D Printer. Retailing at $349.99, this

printer comes in a kit that includes the bare necessities you need to get started.

It is capable of printing a 4 cube. You can also purchase it already assembled for

a little extra. The kit and PLA filament are available at Maker Shed.

The 3D printer I personally recommend is the Afina H480 3D printer. Retailing

at $1299.99, this printer provides the easiest setup right out of the box. Its fully

assembled, comes with a heated platform for the aid of adhesion and for less

chance of warping, and can print up to a 5 cube. It also comes loaded with

its own native 3D software, where you can manipulate your .STL files. It has an

automated utility to calibrate the printers build platform with the printhead,

and also automatically generates any support setup material and the raft, which

is the base support for your prints. There is so much more to it, but as I said I

recommend this for beginners, and it is also available through Maker Shed.

For those who want to print, and are at the hobbyist and semi-professional

level, consider the next generation in 3D printing, the MAKERBOT Replicator.

It is quick and efficient. Retailing at $2899, this machine has an extremely high

layer resolution, LCD display, and if you run out of filament (ABS/PLA), there is

no need to start over; this machine will alert you via computer or smartphone

that a replacement is needed.

There are many types of 3D printer available, with options including open source,

open hardware, filament types, delta style mechanics, single/double extruders,

and the list goes on. My main suggestion is to try before you buy, either at a

local hackerspace or a local maker faire. Its a worthwhile investment that pays

for itself.

If youre wondering whether to go for an open source printer, or a pre-packaged

version, here are some things to consider:

Off the Shelf

Advantages

Should print right out of the box

Less tinkering needed to get good prints

Each printer of a particular model is the same, making it easier to get support

Disadvantages

Making changes may void your warranty

Typically more expensive

May be locked into specific software or filament

Off the Shelf vs. Open Source 3D Printers

Open Source (i.e RepRap)

Advantages

Typically cheaper than pre-built

Allows you to learn more about how the printer works

Easier to make changes to the machine, and complete plans are available

Easier to experiment with, for example using different printing materials

Disadvantages

Can take a lot of work to get good prints

Potentially lots of decisions to make

You may spend as much time working on the machine as actually printing

A pre-packaged printer makes a lot of sense if youre just interested in making

things. The learning process for building your own printer can either be

interesting or a frustrating obstacle, depending on your point of view. However,

when you look at the RepRap printer, its incredible to consider that it is the

product of contributions and the sharing of knowledge from a large community.

If youre not just interested in making things, but making things that make things,

then a RepRap printer might be for you.

Before you begin, its also important to choose your design tools. There are a

multitude of cost effective and free tools out there to get you started.The first

important thing to learn is that the 3D printing process has a required tool-

chain that must be followed, this chain can roughly be broken down into three

parts:

1. CAD (Computer Aided Design): Tools used to design 3D parts for printing.

There are very few interchangeable CAD file formats that are sometimes referred

to as parametric files. The most widely used interchangeable mesh file format

is .STL (Stereolithography). This format is the most important as it used by CAM

tools.

Known as FLOSS (free/libre/open source software), FLOSS CAD tools, for example

OpenSCAD, FreeCAD, and HeeksCAD, for the most part create these parametric

files that usually represent parts or assemblies in terms of CSG (Constructive

Solid Geometry), which basically represent a tree of Boolean operations

performed on primitive shapes such as cubes, spheres, cylinders, and pyramids.

These are modified numerically and with great precision and the geometry is a

mathematical representation of such, no matter how much you zoom in or out.

Building an Open Source Printer

Another category of CAD tool, that represents the parts as 3D polygon mesh, is

for the most part used for special effects in movies or video games (CG). They

are also a little more user friendly, and examples would be Autodesk Maya and

Autodesk 3ds Max (these choices are subscription/retail-based), but there are

also open source and free versions of this tool such as Autodesk 123D, Google

Sketchup, and Blender; I suggest the latter options, since they are free, user

friendly, and they are much easier to learn, since their options are narrowed

down strictly to producing 3D meshes. If you need more precision you should

look at OpenSCAD, as it was created directly for making physical objects rather

than game design or animation. OpenSCAD is easy to learn, with a simple

interface. It is powerful and cross-platform, and there are many examples you

can use along with strong community support.

2. CAM (Computer Aided Manufacturing): Tools handling the intermediate step

of translating CAD files into a machine-friendly format.

Next, youll need to convert your 3D masterpiece (.stl) into a machine friendly

format known as G-Code. This process is also known as slicing. Youre going

to need some CAM software to produce the tool paths, which is the next stop

in the tool chain. Most of the slicing software available is open source. Some

examples are Slic3r (the most popular, with an ease of use recommended for

beginners), Skeinforge (dated, but still one of the best), Cura, and MatterSlice.

There is also great closed source slicing software out there. One in particular is

KISSlicer, which is a pro version that supports multi-extruder printing.

The next stop after slicing is using software known as:

A G-Code interpreter, which breaks down each line of the code into electronic

signals.

A G-Code sender, which sends the signals to the motors on the printer to tell

them how to move.

This software is usually directly linked to an EMC (Electronic Machine Controller),

which controls the printer directly. It can also be linked to an integrated hardware

interface that has a G-Code interpreter built in, which loads the G-Code directly

from a memory card (SD card/USB).

3. Firmware for electronics: This is what runs the onboard electronics of the

printer, and is the closest to actual programming - a process known as cross

compiling.

The last stop is the firmware, which controls the electronics onboard the

printer. For the most part, the CPUs that control these machines are simple

microcontrollers that are usually Arduino-based, and they are compiled using

the Arduino IDE.

This process may sound time consuming, but once you go through the tool

chain process a few times, it becomes second nature, just like driving a manual

transmission in a car.

When I finished my first hackerspace workshop, I had been assimilated into a

culture that I was not only benefiting from personally, but a culture that I could

share my knowledge with and contribute to. I have received far more in my

journey as a maker than any previous endeavor.

To anyone who is curious, and mechanically inclined, who believes they have an

answer to a solution, I challenge you. I challenge you to make the leap into this

culturejoin a hackerspace, attend a maker faire, and enrich your life and the

lives of others.

More Than Just Printing

We hope youve found this white paper useful. If youd like to learn more

about 3D printing, you may be interested in one of these titles:

Please visit www.packtpub.com to view our full range of e-books, or

sign up to PacktLib to get instant access to over 2,000 titles.

Blender 3D Printing Essentials

Gordon Fisher

3D Printing with SketchUp

Marcus Ritland

3D Printing with RepRap Cookbook

Richard Salinas

3D Printing for Architects with MakerBot

Matthew B. Stokes

3D Printing Blueprints

Joe Larson

About the Author

Travis Ripley is a designer and developer. He enjoys developing products with composites, woods, steel, and aluminum, and has been immersed in the Maker community for over two years. He also teaches game development at the University of California, Los Angeles. He can be found on Twitter @travezripley.

Published November 2014 by Packt Publishing Ltd.