Skill Badge Guide: 3D Printing
Created by Adam Kemp
https://learn.adafruit.com/skill-badge-guide-3d-printing
Last updated on 2021-11-15 05:51:12 PM EST
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Table of Contents
3D Printing Overview
3
Understanding the technology
3
Filament types
5
Designing for the printer
7
Free 3D CAD
8
Setting up the machine
9
Bed leveling
10
Scale calibration
11
Running the machine
12
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3D Printing Overview
The 3D printer uses a process called fused deposition modeling to construct a solid
object from a virtual model. This process involves the controlled deposition of a
molten feed stock, typically ABS or PLA plastic, onto a build surface where layer-bylayer the model emerges. Each 3D printer features a series of motors to move the
three axis and the extruder, and a controller to move the motors and manage the
build process.
Understanding the technology
Today's 3D printers are typically made up of 6 main components. There are multiple
methods for configuring the machine and this guide features a machine whose build
platform moves on the X and Y, and the Z carries the extruder.
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The Structure (B):
The role of the structure is to provide a rigid platform for the machines components to
be secured to. The material of the structure can be as unique as the machine itself.
Some common materials are plywood, acrylic, and metal.
The XY axis (E):
The XY axis provides stable, linear movement in the X & Y directions. This mechanism
is controlled by either a belt or screw interface to a stepper or servo motor. The
amount of XY movement per step correlates to the machines resolution.
The Z axis (A):
The Z axis elevates the extruder above the build platform and moves perpendicular to
the XY axis. This mechanism is typically controlled by a linear screw interface to a
stepper or servo motor. The amount of +Z movement correlates to the thickness of
each layer. Some machines move the extruder with the XY axis and the Z axis moves
the build platform. Regardless of the configuration, all three axis are required to
construct a 3D object.
The Build Platform (D):
The build platform is the surface that supports the extruded material while the
machine completes each layer. There are two types of build platforms, heated and not
heated. A heated platform is optimal for larger parts as it helps to eliminate the
problem of thermal contraction of the extruded material which leads to part
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deformation and warping. Printers that print ABS often require a heated platform
while those that use PLA do not.
The Extruder (C):
The extruder is the heart of the 3D printer. This mechanism is responsible for
accurately depositing the desired feed stock onto the build platform. There are
numerous designs and types of materials the extruder can handle. If it is extruding
plastic feed stock, the extruder relies on a toothed feed wheel that feeds the plastic
filament into a heated chamber. This chamber is thermally regulated to the desired
melting point of the plastic and once molten, the filament is forced through a small
nozzle. The diameter of the nozzle dictates the detail that can be replicated by the
machine and are generally ~0.4mm - 0.5mm in diameter.
The Electronics & Software (F, G):
The electronics and software make up the brain of the 3D printer. Designs are
produced on a computer as a solid model and are deconstructed by a G-Code
processor (Skeinforge, Slicr, Miracle Grue, etc.). This piece of software takes the solid
model and "slices" it into a series of layers. Each layer is then converted into a series
of coordinate movements that are fed into the machines controller by the control
software (ReplicatorG, MakerWare, Repeiter-Host, Pronterface, etc.).
Filament types
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Although there is a wide range of filament types a 3D printer can handle, ABS and
PLA plastics are by far the most popular. These two plastics are readily available in a
staggering amount of colors, even glow-in-the-dark!
• PLA (https://adafru.it/cop) - Is a thermoplastic derived from natural sources and
has excellent print qualities. It flows at a relatively low temperature, starting at
~220°C, and does not require a heated build platform. Objects made out of PLA
are rigid and more brittle then ABS. PLA is aslo prefered over ABS when used in
areas with poor ventilation due to its relatively non-offensive smell.
• ABS (https://adafru.it/coq) - Is a synthetic thermoplastic commonly used in the
automotive industry and also has excellent print qualities. It flows at a
temperatures starting at ~230°C, but can be extruded at higher temperatures
then PLA due to its chemical stability, but requires a heated build platform.
Objects made out of ABS are rigid and tend to bend before breaking, unlike
PLA. Lastly, proper ventilation is a must due to the offensive fumes generated
when printing ABS.
• PLA/PHA (http://adafru.it/2063) - A compromise between PLA and ABS at an
affordable price. Like PLA, PLA/PHA is made from renewable resources and is
biodegradable. Polyhydroxyalkanoate (PHA) adds toughness to the PLA, making
it more malleable and giving it a feel similar to ABS. The colors are opaque and
remain vibrant after printing. However unlike ABS, it is not prone to warping and
can be printed easily on an unheated printer bed. It flows at a relatively low
temperature, starting at ~220°C.
• NinjaFlex (http://adafru.it/1690)- Specially formulated thermoplastic elastomer
(TPE) that produces flexible prints with elastic properties. Perfect for wearables,
LED Diffusers, Bumpers, Insulation, Grips, Buttons andBuoyancy. It flows at
temperatures starting at ~240°C, but can be extruded at higher temperatures.
• SemiFlex (http://adafru.it/2321) - boasts half the flexibility, more strength and
reliability for your 3D printing projects. It's slightly more rigid with a higher level
of detail and with added shock-absorption. It can also handle unsupported
vertical printing. Flows at temperatures around ~230°C
• BambooFill (http://adafru.it/2475) - Made with actual recycled bamboo! This
material can be stained and sanded. Smells and feels like wood! Works well on
both heated and non-heated build platforms. Flows at a temperatures starting at
~220°C.
• BronzeFill (http://adafru.it/1830) - Print with actual bronze at home! Straight from
the printer parts look almost laser sintered with a matte finish but with a bit of
sanding and polishing the bronze particles will start to shine and shimmer unlike
any 3D printing filament you have seen before. The weight of the material is
something special, about 3x heavier then regular PLA filament. Prints easily on
an unheated printer bed. It flows at a temperatures starting at ~220°C.
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• CopperFill (http://adafru.it/2128) - Same properties as BronzeFill but with a gold
color after polishing!
• Magnetic Iron (http://adafru.it/2797) - This filament behaves similarly to iron even to the point of rusting - making it a great choice for costumes and props.
it's actually "ferromagnetic" as opposed to magnetic. This means that magnets
will stick to items printed with this filament but 3D Printed items will not behave
as magnets. Prints easily on an unheated bed. It flows at temperatures starting
at ~220°C.
• Conductive PLA (http://adafru.it/27032703) - A great way to make something
with an LED, touch sensor, or some other electronics through your 3D printer.
The filament is great for low-voltage circuitry. A great way to think of it is that
anything you can run through a 1K resistor should work witht his filament. Prints
easily on an unheated bed. It flows at temperatures starting at ~220°C.
• Glow in Dark (http://adafru.it/2338) - Literally make your work glow! During the
day it's a beautiful creamy color which prints to a perfect smooth finish.
Phosphorescent pigment is matched with PLA/PHA compound to make prints
glow in the dark. For a better and longer lasting glow time print your models
with 100% infill and charge up your models with UV LEDs or high power lights, or
just let them enjoy the sunlight for a bit. Prints easily on an unheated bed. It
flows at temperatures starting at ~220°C
Designing for the printer
In order to produce 3D printer compatible objects, it is important to understand its
limits. I like to think of a 3D printer as a spaghetti machine. It carefully stacks noodles
on top of each other, and if there isn't enough noodle to stack on, it droops. The
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following three design elements can be implemented to help prevent drooping and
will allow you to successfully print overhangs.
1. The 45° Rule: In general, 3D printers are restricted to overhangs that are under
45°. This allows for enough material to be present under the new extrusion and
helps to prevent drooping.
2. Peaked circles: If you need to create a circular feature that is perpendicular to
the build platform, taper the top of the circle with two tangential lines so that the
45° rule is not broken.
3. Support structure: Many slicing engines will detect overhangs and can generate
a brittle support structure that provides support for overhangs over 45°. This is a
nice feature to use, especially when overhangs are unavoidable, but usually
uses a ton of filament in the process.
Check out Makerbot Thingiverse (https://adafru.it/cor) for models and design ideas for
your next project. Their friendly community has a ton of 3D printer compatible models
to share.
Free 3D CAD
There are many FREE CAD suites that make designing for the 3D printer a breeze.
Each one has its strengths, so try 'em all and see which works best for you!
• 123D Design (https://adafru.it/aVV): Autodesk's 123D Design provides a very
capable solid modeling environment that operates on Mac and PC. The 123D
tool set is similar to commercial suites making it a good free alternative to
software such as Solidworks and Fusion 360.
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• Blender (https://adafru.it/aVR): This feature rich software can create everything
from solid models for printing to full fledged, cinema quality, video. Although the
learning curve is a bit steep, there is a huge amount of support available in their
community forum and elsewhere online.
• Tinkercad (https://adafru.it/aVU): Revived by Autodesk, Tinkercad provides an
easy to learn solid modeling environment that links directly to your Thingiverse
account. Unlike 123D Design, Thinkercad is capable of importing and
manipulating existing solid models and runs entirely "in the cloud."
Setting up the machine
Before you operate your machine, check the following to ensure its proper operation:
1. Make sure the filament spool is installed properly and turns freely.
2. Gently move each axis and ensure they move smoothly.
3. Check that the build platform is level.
These three checks will help to eliminate many of the problems that inhibit a good
print job. If the spool sticks while it unravels it will pull up on the extruder and may
prevent it from extruding. If the axis don't move freely, they may need to be greased
or realigned. This will help prevent the stepper from skipping a step, resulting in a
shifted print job. Finally, if the build platform is not level the first layer will most likely
not stick evenly and will cause distortion or warping of the printed model.
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Bed leveling
The build surface needs to be level to ensure the filament properly sticks to the
surface and to provide a secure foundation for the print job. The bed can be leveled
by either mechanically leveling the bed or using a raft to accommodate for
unevenness.
• Mechanical Leveling - The easiest way to check this is to command the printer
to "zero" the axis and move the extruder to its lowest position. You should be
able to insert a sheet of paper between the build platform and the tip of the
nozzle. If there is a gap, gently raise that side of the build platform using the
adjustment screw or a shim and continue checking the remaining corners of the
build area.
• Extrusion Raft - If the build platform is warped, or cannot be leveled, try printing
your next object with the "raft" feature enabled. This will deposit a thick grid of
material onto the bed at the beginning of each print and will eliminate most
adhesion problems.
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Scale calibration
Scale calibration illustrates the process in which you compare the desired dimensions
with the actual dimensions your printer produces. The easiest method for
accomplishing this is to start by printing a calibration object, like a Calibration Cube (h
ttps://adafru.it/cos) or the Calibration Vector (https://adafru.it/cot). Once complete, use
a set of calipers to check the dimensions and record your results.
If the dimensions are not to your liking, there are a few quick tweaks you can
implement to improve your results:
1. Novice: Simply scale your object before printing. If your calibration object
measures 10.5mm, and it should be 10.0mm, scale the object down to 95.24%.
(10.0mm x 100%)/10.5mm = 95.24%.
2. Intermediate: Edit the firmware to reflect a more accurate steps/mm calculating
the required steps/mm vs the actual steps/mm.
3. Expert: Change both the feedrate and flowrate as they dictate how much plastic
is distributed per mm. These settings can be used to fine tune your printer once
you are close in calibration.
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Running the machine
After you have completed your quick mechanical check, turn on the printer and open
your control software (ReplicatorG, Makerware, etc.). Import your model into the
virtual build area and preheat the extruder (and platform if a heated platform is used)
since this usually takes a good bit of time. Depending on the software you used to
create your model, it might be oriented improperly with respect to the build platform.
Simply drag the model so that it is positioned within the printer's build area and have
the software place it onto the platform. This will ensure that the first layer adheres
correctly and that the object is level. Follow your printers directions regarding
sending the job to the printer, select your desired resolution and fill density, press
print and watch the magic happen.
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Like any machine, 3D printers should not be left unattended while they are printing.
This is especially important with large print jobs as the heat generated by the printing
process can cause mechanical failure that, if left unchecked, can cause a fire. Make
sure you are familiar with your machine's emergency stop procedure. Most machines
feature an emergency stop button (sometimes in the software) to immediately halt the
machine. If all else fails, pull the plug!
When the print job is complete, let your model cool or you might unintentionally mush
it while prying it off the platform. If you model is stuck, use a plastic putty knife to
carefully work around the perimeter of the object until it pops off. Clean up any
excess material and you are good to go!
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