3D Printing

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3D printing is an additive manufacturing process which creates a three-dimensional object from a digital model.There are many different ways to 3D print. At the uOttawa Makerspace, we use FDM (fused deposition modeling) which works by slicing the model into layers and then printing one layer on top of the other. The material most commonly used in the Makerspace is a type of plastic known as PLA (Polylactic acid). This plastic is used for 3D printing because of its relatively low melting point and very low shrinkage rate.

Which 3D printers do we have?

Ultimaker 2+
Ultimaker2+.png
Slicer Cura
Build Volume 223 × 223 × 205 mm
Compatible materials PLA, ABS, Flexible
Minimum Layer Height 0.06 mm
Heated Build Plate Yes
Ultimaker 3
Ultimaker3.png
Slicer Cura
Build Volume 215 × 215 × 200 mm
Compatible materials PLA, PVA, Flexible
Minimum Layer Height 0.02 mm
Heated Build Plate Yes
MakerBot Replicator 2
Replicator2.png
Slicer MakerBot Print
Build Volume 285 × 153 × 155 mm
Compatible materials PLA
Minimum Layer Height 0.1 mm
Heated Build Plate No
Dremel 3D20
Dremel-3D20.png
Slicer DigiLab 3D
Build Volume 230 × 150 × 140 mm
Compatible materials PLA
Minimum Layer Height 0.1 mm
Heated Build Plate No
Raise3D N2 Plus
Raise3D N2 Plus.png
Slicer ideaMaker
Build Volume 305 × 305 × 605 mm
Compatible materials PLA, ABS, PVA, Flexible
Minimum Layer Height 0.01 mm
Heated Build Plate Yes
Markforged Mark Two
Mk2.png
Slicer Eiger
Build Volume 320 × 132 × 154 mm
Compatible materials Nylon, Onyx, Carbon Fiber, Fiberglass, Kevlar
Minimum Layer Height 0.1 mm
Heated Build Plate Yes

Video Tutorial

How do I 3D print at the Makerspace?

At the Makerspace we have several different types (brands) of printers. When printing you will encounter either the Ultimaker, MakerBot, or Dremel. In general, the processes are similar.

  1. Create/find a 3D model
  2. Save or download the model as an .stl
  3. Open model in a slicer
  4. Send the code to the 3D printer
  5. Start the print

Create a 3D model

There are many ways to create or find a 3D model. If you want to browse through a library, Thingiverse or Youmagine. These sites are a great way to inspire yourself. If you are more of a do it yourself type of person there are several programs you can try.

If you are a beginner, try Tinkercad. This is a browser based 3D design application that is very simple to learn. For more information check out this handy guide. If you need something a little more advanced, check out Fusion 360 (free for students. teachers, and educators).

Save or download the model as an .stl

What is an .stl file? It is a stereolithography file format. This type of file uses a web of polygons to describe a 3D object. It is this easiest and the default file type with most of 3D printing software.

In Tinkercad, click on Export a new window will pop up and then select .STL

In Solidworks, click File-> Save as. A new window will appear. Choose the file type .stl.

Open Model in a slicer

Your .stl file contains a set of triangles in 3D space. If you send this to a 3D printer, it will not know what to do. A slicer “slices” the 3D object into layers and then generates machine code. Different printers work better with different slicers. The slicers need to be downloaded onto your computer. However, all our computers have all the software for each of our printers.

Send the code to the printer

The Ultimaker = Cura

  1. Open file in Cura
  2. Select the settings you want for your print. (For more information about printer settings and other things you can do in this porgram click here)
  3. Save to file. Make sure you are saving to the SD card


MakerBot Replicator = MakerBot Desktop

  1. Open MakerBot desktop
  2. Click add a file
  3. Select the right printer. We have both Replicator 2 and Replicator 2x. To do this click on “device” on the top menu. Then “select type of device” which can either be one of the two previously mentioned printers.
  4. Send your file to the device. There are two ways of doing this, either using an SD card or a usb cable.
    1. SD Card: Click “Export Print File” Replicators only work with 2GB SD cards (or smaller), if you try to use anything bigger you will get an “SD card read error”.
    2. USB Cable: Connect your printer to your computer using a usb cause. You should see the printer at the bottom of the MakerBot Desktop screen. Click Print. Once you have clicked print, you unfortunately cannot unplug the computer.


Dremel = Dremel Idea Builder

  1. Load your .stl file by clicking the load button on the menu on the left hand side. You can modify your object (scale, move, or rotate) using the buttons on the left hand side
  2. Click build.
  3. Select your settings and your method of printing. Either using an SD card or a USB cable.
    1. SD card: You are saving the machine to an SD card and moving the SD card to the printer
    2. USB cable: You are using a USB wire to transfer the fire to the printer. What is nice with the Dremels is the file is downloaded to the machine. Therefore you can unplug the wire when the file has transferred.

Start the print

Starting your print is very simple. Simply save your file to an SD card or connect your computer to the printer and click print or build.


Ultimaker

  1. Save your file to an SD card. Any size SD card will work.
  2. Walk over to the printer and insert the card into the SD card slot located on the front of the printer.
  3. Turn on printer. There is an on/off switch located at the left hand side of the Ultimaker. This is also a good time to make sure that there is filament loaded into the printer.
  4. Using the knob, select print. To “select” you simply press on the knob. This will take you to the SD card page, scroll through the files and select yours. Usually the most recent files are found at the bottom of the list. Selecting the file, should start your print.


Dremel

If you are using a USB cord, the print with start automatically when you hit build in on your computer. Follow the following step if you are using the SD card.

  1. Place your SD card in the SD card slot in the 3D printing. This is found on the right hand side near the front of the printer.
  2. If the 3D printer is not already on, turn on the printer using the on/off switch located at the right hand side near the back of the printer.
  3. Using the front screen, press build ->The picture of an SD card ->select your file -> Build.

Choosing your Slicer Settings as a Beginner

Since the Ultimakers are the most frequently used printers at the Makerspace, this article will be focused on the use of the "Cura" slicer, specifically Cura version 4.x.x. While this article may be specific to Cura, the software is based on an open source engine, so the same principles and settings should carry over to any slicer. This article will also focus only on the beginner "Recommended" settings interface,

Choose your 3D Printer

After installing Cura, you will be prompted to select your model of 3D printer. If you are printing at the Makerspace, this means you must select the Ultimaker 2+ or the Ultimaker 3 from the "Add a non-networked printer" window. Once selected, your Cura window should now display a visual representation of the interior available print volume.

Load your 3D Model

Once the correct 3D printer has been selected, load your model (.stl or .obj file) into Cura. This can be done by either dragging the file and dropping it into the Cura window, by clicking File -> Open Files (Ctrl+O), or by clicking the "Folder shaped" icon.

Choose your Layer Height

Under the "Print settings" window, you will notice a slider referred to as "Profiles - Default", with numbers ranging from 0.06 to 0.6. The numbers refer to the layer height (sometimes referred to as "resolution") in millimeters, which is the vertical (Z-axis) height of each layer of plastic the printer lays down. The lower the layer height, the longer it will take to print, but the vertical quality (slopes) will be better. If your model lacks any slopes or curves running vertically, lower layer height numbers will only take longer to print, without adding any major improvements in quality.

Weigh the pros and cons for your specific model, decide on what layer height you want to use, and click on the slider which layer height you want to print in. In most cases, 0.15mm layer heights should be a good balance of speed and quality.

Choose your Infill Percentage

To save on material, rather than completely fill a print a solid part with plastic, 3D printers will print what is called an "infill". Infills are usually by default a grid-like pattern that gives a 3D printed part rigidity and density. The "Infill (%)" slider allows you to select how dense (in percentage) the grid pattern inside the model will be, 0% being completely hollow, and 100% being completely solid. The higher the infill percentage, the stronger your part will be, but the longer it'll take to print.

It is a common misconception that 100% is always the best solution to creating a strong part. While 100% infill will create the strongest possible part, the ratio between printing time and part strength worsens as you increase the infill density, especially after approximately 60%. Selecting 100% is therefore often a waste of time and material in comparison to lower infills.[1]

In other words, if your part will not be facing any mechanical strain, we recommend you select an infill percentage between 5-20%. If strain is expected and strength is required, use 60% at the very most.

Supports

Support towers are columns of printed material (usually the same material as your printed model), designed to add support to any "un-printable areas" during the printing process. The support towers are designed to be "easy to remove" once the print has finished (you may find that this isn't always the case however), and for many models it may be necessary to enable supports in order to ensure successful printing. Once your print is completed, you will have to remove the support material with your hands, or with tweezers if necessary.

Ideally, you would have designed your model to have as little overhangs or suspended parts as possible, though sometimes that will be unavoidable. By clicking the "Support" check box on Cura will have the software automatically generate support towers to any areas of your print that the software determines as a "challenging area" (overhangs, parts suspended mid-air etc...). If you are unsure whether your model needs supports, keep the box checked to be safe.

Adhesion

You'll notice that this box is checked by default. In the context of the "Recommended Settings" window on Cura, "Adhesion" refers to an outer thin "brim" of plastic printed around the model (there are different types of adhesion, which will be explained in-depth in the advanced article). This brim is to ensure that the part stays in place during the printing process. The brim of plastic should peel off very easily, so it is extremely beneficial and there are almost no downsides to having this setting enabled. As a beginner, we recommend that you keep this box checked.

When to Use Supports?

Without supports, printing the letter "T" will result in failure or reduced quality.
Unlike the letter "T", printing the letter "Y" without supports will be successful.

Supports are one of the most significant contributors of the quality of your print, for better or worse. Since 3D printers cannot defy gravity, most models with any geometry suspended in mid-air will require some form of support structure to ensure a successful print. However, since support structures will make contact with your model, surface scars will form at these points of contact, and enabling supports for a print that does not require them will lead to worse quality for no benefit. Using supports when they aren't necessary also leads to wasted plastic, and more time wasted removing them afterwards. Thus, being able to recognize when supports AREN'T required, and knowing what settings to use if they ARE required are essential skills for a 3D printing enthusiast!

Overhangs

Imagine 3D printing the capital letter "T" in an upright orientation. This would be referred to as an "overhang," as a portion of the "T" overhangs from either the left or right sides of the letter. Since the 3D printer isn't capable of laying down flat and even layers of plastic in midair, this print would most likely fail or result in "stringy" quality on the overhanging surfaces. A "T-Overhang" would be an example of an overhang that would require the use of supports.

However, not all overhangs require supports, imagine 3D printing the capital letter "Y" in an upright orientation. This would also be referred to as an overhang, since the top of the "Y" will overhang from either the left or right sides. One may think because of the overhangs, supports would be required, however, printing the "Y" without any supports would result in a successful print. Since the overhanging portions of the "Y" gradually slope upwards, and the 3D printers operate on a layer-by-layer basis, each layer of the "overhanging portion" will be supported by the previous layer. These overhanging portions are often described with the term "overhang angle", and an overhang angle of less than 45° is usually safe to print without supports. Since the "T" has an overhang angle of 90° with the vertical, it would be considered unsafe to print without supports.

Therefore, when designing models for 3D printing, avoid "T" style overhangs, and use overhanging angles of 45° (or less) as much as possible. If you're printing a model with overhangs, try to re-orient it to minimize the amount of "T" style overhangs. For example, orienting the letter "T" so that it lays flat on the bed ensures that supports will not be required.

Bridges

This section is under construction.

Choosing your Slicer Settings as an Advanced User

This section is under construction. If you want more information on the print settings available in Cura, check out the Cura documentation on Ultimaker's website.

Post-Processing 3D Prints

This section is under construction.

References

  1. Alvarez C, Kenny L, Lagos C, Rodrigo F, & Aizpun, Miguel. (2016). Investigating the influence of infill percentage on the mechanical properties of fused deposition modelled ABS parts. Ingeniería e Investigación, 36(3), 110-116. Available online: http://www.scielo.org.co/scielo.php?script=sci_arttext&pid=S0120-56092016000300015