FDM 3D Printers

First introduction

FDM 3D printer, aka Filament Deposit Material 3D printers, are the main technology in 3D printing. The reasons for their popularity are multiple. The price of a FDM 3D printer is now very low while the improvements keep coming. Both while allowing for quite large pieces to be printed and be tuned precisely to achieve the right ratio wanted between quality of the pieces and speed of printing. They also allow for a wide variety of type of plastic which multiply the uses you can have from a 3D printer.

Practical relevance

– This is what you will need the knowledge and skills for

After this module, you’ll understand how a FDM 3D printer works and how to turn a computer design into a finished piece

Overview of learning objectives and competences

In this module, you’ll learn how to setup the machine by calibrating the printing bed, changing filament, etc. You’ll also learn how to prepare a file on the computer to be send to the machine. You’ll then learn how to take that piece and finish it by removing supports, assembling and smoothing. You’ll also learn how to troubleshoot problems on your prints or the printer and how to fix them. In the end it will be presented to you on how to maintain your 3D printer to keep it running well for a long time.

Required skills for this module

Basic computer skills and 3D conception skills learnt in module 10: 3D Conception

Introduction

In this part you’ll learn how a 3D FDM printer works, the different types of FDM printers and the applications 3D printing is used for.

Pictures by Lévi PONSARD
Pictures by Lévi PONSARD

As the name indicates, Filament Deposit Material 3D printers, or FDM for short, works by depositing a filament of plastic. That filament is moved around, either by the head of the printer or the printing bed to draw a design, layer by layer until the piece is complete. In slightly more details, the filament, usually in the form of a roll, is pushed by a motor into the head of the printer. That head will heat up the filament to a desired temperature depending on the material used. The filament is now melted enough to stick and fusion with previous layers.

That part pushing the filament to the printing head is called the extruder. There’s usually two types of extruders FDM 3D printers use:

  • Bowden extruder where the extruder is away from the printing head and pushes the filament through a tube into the printing head.
  • Direct drive extruder has the extruder as part of the printing head so that the filament is directly pushed into the printing head.

A direct drive extruder usually comes with more benefit since the extrusion is so much closer to the printer’s head. However, Bowden extruders are usually cheaper to implement for manufacturers which is why it’ll often be the preferred way to build cheaper printers.

Some of the advantages of direct drive, which will be expanded on later, are more consistent extrusion, better retraction and being able to print flexible filaments like TPU. Direct drive also does have downsides such as more vibrations as the head has to move around with more weight attached to it. The other main downside is in terms of troubleshooting and maintenance as it’s harder to realise which part between the extruder and the head is faulty and also usually harder to take it apart compared to a Bowden extruder where both parts are clearly separated.

The extruder isn’t the only part of an FDM printer that can be different, while the general operation of all FDM printers is the same, the way the pieces move together can vary widely. Let’s divide these in 2 main categories: Delta printers and Rectilinear. While there’s technically other types of printers, they’re very rare to work with so I won’t explain them in this learning material. In case you are interested in the other types of printers you can look up Polar, Scara and robotic arm 3D printers.

Picture by Matti Blume
Picture by Lévi PONSARD
Delta printer. Picture from Geeetech Rostock

Delta printers work by supporting the extruder with three arms arranged in a triangle. Each arm can move independently which allows the extruder to move in all directions while the printing bed stays stationary. Its advantages are the speed at which it can print but the disadvantages are often poor quality prints and much harder maintenance and troubleshooting. They’re also not as popular as rectilinear printers which means it’s also often harder to find great help online.

Rectilinear, also called Cartesian, printers is probably what you think of when you imagine a 3D printer. As their name indicates, they work by having each of the 3 axes in a rectilinear configuration. The rectilinear printers can themselves divided within 4 categories:

  • Mendel-style,
  • Darwin-style,
  • CoreXY and
  • Belt printers.

The Mendel-style 3D printers are the most common ones of the low cost 3D printers. The printing head will move along the X-axis on a bar while it also moves up and down on the Z-axis. The last direction is done by the printing bed itself, moving back and forth on the Y-axis.

Creality Ender 3Pro a Mendel-style 3D Printer. Picture by Lévi PONSARD

The Darwin-style 3D printers, also sometimes called H-bot, have the printer’s head moving on the X and Y-axis while the Z-axis is done on the printing bed itself.

Creality Ender 5Pro a Darwin-style 3D Printer. Picture by Lévi PONSARD

CoreXY 3D printers are very similar to Darwin styles with the printer head moving on the X and Y-axis. But instead of those being done by two separated axes, the Core-XY printers use two motors and two belts attached to the printing head itself and move both independently to move the head on the XY plane. The Z-axis is also done on the printing bed itself.

CoreXY 3D Printer. Picture by Ion GURGUTA

Finally, the belt printers are a bit on a class of their own. The bed itself is replaced by a moving belt. It first serves as the Y-axis, which is usually the depth of the printing bed but can also allow for continuous printing which in theory gives you an infinitely long Y-axis. This infinitely long Y-axis can either be used to print multiple objects in continuous as the objects get pushed away by the belt so the printer can restart a new one or you can simply print very long objects. 

Creality CR-30 a belt printer. Picture by Creality3D

Because of the belt design, the other two axes need to be tilted 45°, which means the head will be at a 45° angle when printing too and moving on the X and Z-axis. These facts can both create new challenges but also new benefits compared to the other printers. Such as having to rethink the way you prepare your files to be printed but also being able to print some objects without supports that would need support on a more traditional printer.

Here’s a small graphic to visualise this whole FDM 3D printers family tree:

Understanding these categories can be very helpful when searching for a machine and the general understanding of how each machine works can be very useful to understand their limitations and to troubleshoot issues. Now that we know about the different types of FDM printers, let’s look into the different applications.

Picture by Luca Depolo

As with every process, FDM 3D print has its advantages and drawbacks. Such as being able to quickly go from a design to a printed piece with the drawback that each print itself is much longer compared to other types of manufacturing like injection moulding. The applications will reflect these advantages and drawbacks. One of the main applications is prototyping. As huge production needs to be done with injection moulding for plastic parts, these moulds are really expensive and take a while to make. So making a mould for every prototype is inefficient in many ways. This is where 3D printing comes into play. With 3D printing, you’ll be able to create that prototype much faster and infinitely cheaper. This allows you to iterate on designs very fast while being able to test a part that is going to be very functional in comparison to other methods of prototype creation.

Picture by APN Photography

Another application can also come from pieces you don’t need to produce in large amounts. For these, injection moulding also doesn’t make too much sense and 3D printing can be a good alternative. Furthermore, going into this same logic, 3D printing can give an affordable option to smaller businesses or even amateurs. You have an unusable piece of hardware because a small piece of plastic is broken and the guarantee has expired? You can design it or find a file online, print it and give a second life to your hardware. This scenario just described is one of many makers can find themselves in. Another scenario would be during the Covid-19 pandemic, makers around the world helped out by making face shields or mask straps. Here’s an example picture of such face shield made with the help of FDM 3D printers.

Talking about amateurs’ uses, there’s obviously a great artistic freedom given by such tools and decorations made from 3D printed parts are everywhere when looking online.

Picture by Hugo1989 from shutterstock

In the medical sector, 3 D printers are used especially in the making of personally fitted prosthetics. Since the demands in shapes are different for each person in need, 3D printing can fit that need very well.

Picture by Malikov Aleksandr from shutterstock

3D printing even has culinary applications. You can create moulds that can be used in lots of different applications and there’s even exist 3D printers that can print with food such as chocolate.

Picture by Tinxi from shutterstock

This list is non-exhaustive as 3D printing applications can find themselves some uses in many different sectors of activities, this small list should give you an idea of the diverse potential of FDM 3D printing.

Security measures

In this part you’ll learn how to engage with a FDM 3D printer in a safe manner.

Before actually using the 3D printer, some precautions have to be taken. Risk of burning or other injuries are possible if handled by untrained personnel. The main source of danger comes from the nozzle heating up. This part can reach temperatures well above 200 °C. Needless to say that touching the nozzle at those temperatures will burn your skin. Because of those reasons, never touch the nozzle when it’s hot, you’ll be able to check the temperature of the nozzle on the screen of the printer as explained later. If you do need to handle it uses tools such as pliers and wrenches as well as heat resistant. Another source of danger is the vapour emitted by melting the different types of plastic. The printer should be in a well ventilated room so that the vapour doesn’t start to accumulate. While not being from the printer itself, there’s often risks of cut as you’ll often have to use cutting pliers or cutters.

Picture by Lévi PONSARD

In addition to this, the room should be equipped with:

  • A dry powder or a CO2 fire extinguisher in case the device starts burning. Do not use a water or foam-based fire extinguisher as those do not work on electrical devices.
  • A first aid kit and
  • A fire blanket in case of injuries. 

Setting up the Software

In this part you’ll learn how to use a slicing software to turn a 3D design into a readable file by the 3D printer.

As explained in the introduction, a 3D printer works in a very simple way. It’s only controlling a few axes. The 3D printer actually does not have an understanding of the 3D objects. It simply reads lines of commands to control those different axes. This means you can’t just transfer a 3D file like an “.obj” or a “.stl” to the machine and expect it to print. You’ll first have to go through something called slicing software to convert this 3D model into a set of lines the 3D printer can read. The slicing software, as its name indicates, will slice the model into a bunch of layers, then calculate the tool path to create each of those layers. These software’s are very complex and smart. They can also calculate things such as where you’ll need support, change the size of your models, duplicate them, and lots of other functions.

We’ll be using the slicing software called Cura, from Ultimaker™. This is a free and very effective tool that’s used by a lot of makers around the world. It’s consistently in development and will allow us to go really deep into the printing settings. It’s also really easy to set up almost any printer to work with Cura as it comes with a wide range of manufacturers and printers that already have profiles. Even if your particular printer isn’t in that list, the profile of that specific printer will most likely be available online and in the worst situation, you’ll be able to create a profile yourself.

You can find the last version of Ultimaker Cura on https://ultimaker.com/software/ultimaker-cura. We’ll be using version 4.10.0 for these explanations. I’d suggest still using the latest available version and not specifically try to get the 4.10 one as you’ll have better functionality by keeping your software up to date.

When you start Cura for the first time, you’ll have some terms of services to agree with. It’ll also ask you if you want to connect to your ultimaker account, which is not required if you don’t want to. Once that’s done, Cura will also ask you to add a printer.

If your printer is connected to the same local area network (LAN) as your computer, it’ll appear under the “add a networked printer”, otherwise you can find it under “add a non-networked printer”.  The list is ordered in alphabetical order of the manufacturer. Clicking on the manufacturer will show the list of models available. I’ll select the Creality Ender-3 Pro as this is the printer we’ll be using. In the next part, you can see all the settings of the printer you selected.

The printer and the Printhead settings should already be preset correctly for the original printer without any modification. As well as these settings, you can see a “Start G-code” and “End G-code” at the bottom of this window. The G-code is the language the machine understands that will be used to actually 3D print. Do not worry, you do not need to understand how to read or write G-code to use 3D printers. The slicer software will automatically generate G-code from your models. When you generate a file to be printed, this starting and ending G-code will automatically be put at the start and at the end of your file. If you want your printer to do some specific operations before or after your print, you’ll be able to set them here. For example, you could retract the filament a few millimetres at the end of each of your prints to make it easier to change filament.

By default, for this specific printer, the printer will automatically draw a line at the start of the print. This allows you to see if your bed is levelled right and also drain a bit of filament which will clean it from any previous filament you had in there before. These explanations won’t go over G-code too specifically but if you’re interested, you can start by reading the comment on each line of code in these few lines which will explain what each of them do. You can click next to finish adding the printer. You can change all those settings also at a later stage of the progress if needed.

Let’s now take a look at Cura’s interface:

In the top left, in red, you can see the main menu. You’ll be able to open and save projects here, edit the models, change the printer and Cura’s settings, etc.

In the top middle, in yellow, are the different steps of operations.
Prepare will allow you to import models, edit them and set up the printing options.
Preview will allow you to preview the tool path, a very important step to make sure the print will be correct.
Monitor will allow you to monitor the printing as it is happening. To use this function you’ll need your printer to be connected to the same network as the printer needs to be able to communicate to Cura.

Just under that, in green, you’ll find the main tools. This is where you’ll be able to import a model, change the printer, change the material and change the printing settings while in the preparation step. These will change when going to the other steps.

In the rest of the screen, in blue, you can see a 3D view. This view will allow you to preview your models as well as manipulate them.

Let’s now import a 3D model to go over all the useful options. For an important model, you have several options, you can go through the main menu, go to “File” then “Open File(‘s)…” and select your files. You can also simply click on this button, which will give you the same menu:

You can also just drag and drop files from a folder into the 3D View as well.

Important
File type: Do not forget you can’t import any kind of files. You’ll need a supported file format such as an STL, OBJ or 3MF to cite a few. You can see the full list of supported files when going into the “Open file(‘s)” menu. To export your file into a supported format, refer to the learning unit 10 (3D conception) of this learning material.

I’ll use the open source file “Benchy”. This is probably the most famous 3D printed file which will allow us to test our printer and settings. You can find it here. Once you import your file, new tools will become available.

Before touching these new tools, let’s first learn how to move the view around as it’s really important in any 3D Software:

  • Holding down the right click allows you to rotate the view around by moving the mouse.
  • Holding down the scroll-wheel allows you to pan the camera left to right or up and down by moving the mouse.
  • Scrolling on the scroll-wheel allows you to move forward and backward.

I would suggest moving around your model using these 3 ways to get used to it.

Let’s now look at the tools that appeared on the left. First, to even be able to use them, a model will have to be selected, if the tools are greyed out, left click on the model to select it and unlock the tools. The first tool, move, allows you to move the model around on the printing bed. You can easily type values on those coordinates, use the gismo arrows on the model itself or drag and drop the model around in the 3D view. You can also lock the model to make sure it can’t move around in case you miss-click. If the model ever has grey lines going across it like this.

It means a part of your model is outside of the printing volume. You’ll have to move or resize it so that it fits in the printing volume of your specific printer. Talking about resizing, the second tool, scale, allows you to resize your model. You can either change the size through the preferred unit, here in mm. As a percentage of the original model or through the gismo like the move tool. If “Uniform Scaling” is checked, any change of any values will uniformly change the others to keep the model’s original shape.

Practical Tip
Using the right unit: Talking about scales, an exported model in the same unit as the one set in Cura will have the exact same size when being imported and shouldn’t have to be resized. I’d highly suggest keeping everything in millimetres (mm) as that’s the unit that’s used by almost everyone. That way you can make sure almost any file you import will have the right size.

The third tool, rotate, is probably a lot more important than it might first look like. As its name would indicate, it allows you to rotate the model. You can use the Gismo on the model to rotate it freely around the 3 axis or use one of the three options available when you select rotate. You can reset all the rotations you’ve done. Lay the model flat automatically. Or lay the model flat by selecting a specific face. The “Snap Rotation” checkbox will allow you to rotate per 5° which makes it much easier to easily rotate specific values like 45, 90 or 180 degrees.

Now the reason I’ve said this part is a lot more important than it might first look like goes back to how an FDM printer works. Since the printer will print a layer on the X and Y axis then move up the Z axis to print the next one, the orientation of the model is going to have huge impacts. These impacts will have to do with the ease of printing the model, the visual quality of the model, the quantity of material used, the time to print, and even the physical attributes of the printed model.

First, the ease to print, as the layers are built on top of each other’s, there’s a few guidelines that come with that: 

  • A large flat surface in contact with the printing bed is one of the main ones as it’ll ensure your print sticks to the printing bed. 
  • Not having too many overhangs. Overhangs will need to usually be accounted for by supports which will increase the quantity of material used as well as the printing time. Even when supported well, the overhang part’s quality won’t come out as great.

Secondly, the physical attribute of the print, each layer will be fused to the one under. That link, however, is not as strong in-between layers, as it is on a single layer of continually extruded material.

Practical Tip
Filament Follow Function This easy to remember rule, Filament Follow Function, is a great guideline to remember both when designing a 3D printed part but also for its orientation when printed. You need to always think of the forces that will be applied to the model and design and print it in a way that those forces never force against the layers themselves as those are most likely to fail first.

I’ll point out again that these points are as important to think about when orienting your model as they are when creating them. It’s also sometimes easier to cut the models into several different parts that’ll be assembled later to allow you to print each part in a different orientation and with less support.

The fourth tool, mirror, is pretty straight forward, when selected, it allows you to mirror your model on any of the 3 planes.

The fifth tool, “per model setting”, allows you to select different options for each model you have imported. It’s especially useful to create custom supports if you have specific needs that aren’t met by the automatically generated supports of Cura. You can also use it to have different printing settings per model.

The sixth, and last tool, “support blocker”, allows you to stop the creation of supports on specific spots. You can left click where on your model you’d like supports to be blocked. To delete those cubes, left click to select them and press the delete key on your keyboard.

Once the model is at the right position, size and orientation, we can start setting up the slicing options.

To do so, let’s look back at the main tools at the top. The first thing to set is the printer itself but this should already be done so let’s look at the next options.

This next part allows us to set the material that will be used as well as the nozzle’s size. Setting the material here is one of the most critical parts as this will change a lot of printing settings. Printing with a different material than this was set to will most likely result in a failed print.

Here’s a small list of some of the most common plastic filaments used in FDM printing. You can learn more about the different materials in learning unit 2 (Craft and Material) of this learning material.

  • PLA: PLA is the most popular filament used for 3D printing. It’s the easiest to print and doesn’t even need a heated bed. It’s also biodegradable which can be beneficial but also means it’s not the best material to use if the piece will be used in humid conditions.
  • ABS: ABS is a much tougher plastic and as such will often be used for prints that need to be strong. It’s much harder to print material, not only it’ll need a heated bed, it’ll often also need a closed container to avoid fast cooling.
  • PETG: PETG is another strong plastic. It’s especially good at water resistant applications. It’s harder to print than PLA but not as hard as ABS, you’ll need a heated bed but you don’t need a closed container.
  • TPU: TPU are flexible filaments which give them completely different use cases to the other rigid filaments. Printing TPU will require a direct drive extruder to be printed with any chance of success.

To select the material you’re going to use, simply open the drop-down menu and select the right one. If the filament’s brand is part of the list you’ll be able to select profiles that were made especially for the filament you’re using, you can even find more profiles online if your brand doesn’t show up there. If you can’t find your specific brand, you can just use the generic one as it should be good enough for most filaments of that same material. Furthermore, every setting these changes will be able to be tweaked such as the printing speed and temperature. You can then save these to get the perfect profile for each material and brands you’re using.

The other option you can find here, the nozzle size, is the diameter of the hole at the tip of the nozzle where the filament will come out of.

This value should only be changed if the nozzle itself was changed on the printer. By default, most printers come with a 0.4mm nozzle attached. Let’s dive into the nozzle’s size a bit more to understand what it changes. As the material is pushed through the nozzle, the bigger the hole is, the bigger the diameter of the filament coming out will be. This has several implications.

The first one comes with how thick or thin you can make your layer height. This is because the next layer, when printed on top, needs to fuse with the one under. If not enough material comes out to press against the previous layer, the layers won’t be fused well together resulting in a very weak print at best and a failed one in other cases.

On the opposite of that, if the nozzle is too close to the previous layer with a layer height set too small compared to the nozzle’s size. Too much material will come out of the nozzle and it’ll be squashed into the previous layer. Resulting in low quality print at best and a clogged print head at worst.

The usable layer heights to avoid those two outcomes are between 0.25 and 0.75 times the nozzle diameter. With an ideal layer height of 0.5 times the nozzle diameter. Which means for a 0.4mm nozzle, it’ll be between 0.1 and 0.3mm layer height and an ideal one of 0.2mm. Similar to the layer height, a bigger nozzle will also allow you to print less wall pass for the same wall thickness. I’ll also allow for faster infill. But that doesn’t mean that a bigger nozzle is directly better. As you’ll see with a lot of other settings, this is often a trade-off. Here the trade-off is going to be between quality or precision and print speed. Here’s an example of the different quality compared to the printing time in hours and minutes:

Example
A 0.4mm nozzle is a good compromise between speed and quality. However if you’re mainly going to use your FDM 3D Printer for a specific use, it can be a good idea to change the nozzle accordingly. If the added precision and quality that comes with thin layer height is not important for your use case, then 0.8 or even 1mm nozzle will greatly speed up your prints.

Let’s now look into the actual print settings in the last part of the main tools:

When clicking on it for the first time, you’ll be welcomed by the recommended settings. This will allow you to change in-between some recommended profiles and change a few options. These profiles are a very good starting point as directly customising every setting can become overwhelming, especially as a beginner. However, these recommended settings are also going to become very limiting if you just stop there. I’d suggest to start with them for the first few prints then later on, only use them to get a “close enough” profile which you can tune in the custom settings. The first setting here will change the layer height, but as you can see it’s actually changing a profile. This profile will change more than just the layer height as this is more of a “quality” setting.

Another thing you can notice is how the 0.08 and 0.32 profiles are not available as those can’t be reached by the 0.4mm nozzle we have installed on the printer. As previously mentioned, this setting is going to mainly be a compromise between quality and speed. Here’s an example in these different layer height print times in hours and minutes.

The next setting, “infill (%)”, will change how much infill will be printed inside the model.

A higher percentage of infill will give you a tougher and heavier print but will take longer to print as well as use more material in the process.

The “Gradual infill” checkbox will gradually increase the infill percentage as the print goes higher to give a great support to the top layers. Doing so will give you an inconsistent strength on the piece overall. Do not use 0% infill as your top layers do need some kind of support to print correctly unless you know for sure what you’re doing. I would suggest using 20 or 30% infill for anything that doesn’t need to be very tough then gradually increasing it as needed.

The next setting, “Support”, is a simple checkbox that will allow or not the automated generation of supports.

If enabled, Cura will look at every overhanging part of the model, and if there’s enough room to accommodate them, generate a support structure. You can visualise which part of the model is considered to be overhang by rotating the view under the model and observing it. Any part highlighted in red will be considered to be overhang. Cura simply looks at the angle of each surface and compares it to a set value. That value is controllable in the custom settings. In this example, it’s set to 45°.

However, the fact that a surface is red doesn’t mean it can’t be printed, simply that the angle is lower than the set one. In some situations they won’t be an issue. For this particular model I will not actually need to print it with support as the model is conceived to be printed without. Here’s an example of two prints with red surface where one could be printed without support but the other one would need some.

If you’re not too sure if a model needs or doesn’t need support, it’s better to keep the supports activated as not having support for a piece that really needs it will always result in a failed print.

The last option available in the recommended tab is “Adhesion“, an additional step that the printer performs before printing the actual model. It has two main uses depending on the type of adhesion that’s going to be used.

There are two main uses, depending on the type of adhesion to be used:

  • The first one is to check if the start of the first layer is printed correctly. The first layer is very important to get just right, which we’ll be going into more details in the machine setup part.
  • The second use is to, as its name indicates, create a better adhesion between the model and the printing bed. A print that detaches from the printing bed will also result in a failed print.

However the default adhesion option is recommended is set to “Skirt”. The skirt adhesion option will not be directly connected to the model itself. For this reason, it won’t help create a better adhesion between the model and the printing bed. It can still however work as that first layer test. You’ll be able to change that adhesion option in the custom settings.

Practical Tip
As for the custom settings, we'll get into that now. As this part will take a while, I suggest you go to the slicing part first and do some test prints and then come back here when you have a bit more experience. You can obviously also just continue to read from here if you’d like to learn about the settings more in-depth.

To access the custom settings, simply click on “Custom” at the bottom right of the window. The profile that was selected in the recommended settings will be used to set all the settings. But they’re now editable.

Talking about profiles, the first line in these custom settings allow you to switch profiles as well as manage them to create and edit custom profiles. This will be very useful when you have fine-tuned your print settings.

Under the profile selector, you also have access to a search bar. This search bar can be a good time saver as there are a lot of settings to be edited here. These settings are now divided into several categories. We’re not going to go through every single setting themselves as this would only serve to be more confusing. We’ll focus more on explaining the basic ones and then elaborate further as we need to. To show the settings of a category, simply click on the category itself to open it up:

You might notice that the settings I have here are different from yours, most likely you’ll only have the “Layer Height”, while I can also change the “Initial Layer Height”. The reason is that some settings are hidden by default. To access hidden settings, you can either use the search bar or enable their visibility if you’re going to use that setting often and want it visible. To access it, simply click on the cogwheel that appears when you hover the mouse over one of the categories.

This window is a good place to realise how much you can modify the printing settings. As you can see if you scroll through this window, there’s a few hundred settings to turn on and off to modify as needed. Do not be too scared by the sheer amount of settings available. Most of these will have default values that are already well tuned and never need to be changed.

Practical Tip
Default values: As just talked about, each setting has a good default value. Even if you have access to modifying each and every one of them, you should only modify any if you have a good understanding of the effects it will have. This will also keep it a lot simpler as you’re starting to use these printers. You can start to experiment later as you’re getting more and more into the details of each setting.

1. Quality:
As explained in the past, the main quality setting is the “Layer Height”. As said before, that value should be within a range depending on the nozzle’s size. You’ll also be able to change the “Line Width”. This should be the same as the nozzle’s size by default.

Remember
While the layer height is the most important setting that determines the quality of the result, it should not be forgotten that it also has a considerable influence on the printing time.

Something to note too, if you’ve opened the hidden settings, is the “initial layer” that you can see next to several settings. This initial layer is simply the very first layer that’ll be printed on the printing bed. Since this initial layer is very important to get just right, most settings will have a variable setting for the initial layer that you can mess with. For example, you can print the initial layer at a lower speed to ensure a great adhesion with the bed. This specific behaviour is actually already set by default.

2. Walls:
The walls are the exterior surface on the sides of your model. The settings will mostly consist of changing the “Wall Thickness” or “Wall Line Count”. Thicker walls will help with solidity of the model but will also increase the print time in most situations.

Picture by Lévi PONSARD

The other wall settings will mostly change how the process in which these walls are printed, like which orders they’re printed in, where the Z-seam will be placed, etc. The Z-seam is the position, on the wall, where the printer will start and finish printing that particular wall to go up to the next layer. That position will often leave a tiny amount of extra material as the printer goes to the next level. These Z-seam parameters allow you to edit where that seam should be in case you want it to be aligned or random to make it less noticeable.

3. Top/Bottom:
The top and bottom are the exterior surfaces on the top and bottom of the model. You can set both thickness at once with “Top/Bottom Thickness” or individually. In the hidden settings, you’ll also have access to “Enable Ironing”. This ironing is an extra step the printer will do when printing top layers. This step consists of doing one more layer right on top of the top layers without extruding more material or very little of it. However, the nozzle is still hot during this pass which will smooth out the top of the print. This step adds a lot of time to the print, depending on how big and how many top layers there will be on the print.

Pictures by Lévi PONSARD

4. Infill:
Same as in the recommended settings, you can change the “Infill Density” as well as the “Infill Pattern” which as its name indicates, allows you to change the pattern that will be created inside as the infill. That pattern doesn’t have too much impact and a grid or line pattern will usually work in most situations. Here’s a few examples of some of the pattern options, there’s many more available:

5. Material:
These are the settings that will be automatically changed when you change the material type. The “Printing Temperature” is the temperature of the nozzle that will melt the filament. Make sure to respect the particular material’s temperature you’re using. As well as the default generic material profiles, you can also simply look at the filament roll itself. The temperature range will often be indicated right on it. The “Build Plate Temperature” is the temperature of the printing bed. Some materials will need a much higher build plate temperature than others, for example, ABS. Another important setting you can find in the material category is the “Flow”. This Flow will change how much material is pushed by the extruder. It should normally stay at 100% but can be fine-tuned in case of a small under or over extrusion.

6. Speed:
The “Print Speed” is the speed at which the printer head will move around to print the material. A faster print speed will obviously result in shorter print time. However this can’t always be boosted much higher as you can start losing print quality or simply get to speeds your printer can’t reach. This print speed, as well as the acceleration and the jerk can be set to different values for each part of the print.

Example
Parts such as supports or infill can be printed at higher speed as the quality doesn’t need to be as good but walls and the initial layer are parts where the quality is much more important and will have to be printed slower. All of these different speeds can be set here if you look into the hidden settings.

7. Travel:

Picture by Lévi PONSARD

The travel category has a few settings for the printer head’s travel in-between the actual printing. The two main ones are the retraction and the Z-hop. The retraction is a movement the extruder does every time the printer head needs to move without printing. As the material is being melted in the nozzle, simply stopping the extruder motor is not enough to stop the material from coming out of the nozzle. This can create what’s called stringing. The extra bit of material will come out and stick to the walls as the printing head moves from one part to the next and create a string in-between.

The Retraction can help avoid this issue by retracting the material when the printer needs to move without printing. “Enable Retraction” will allow you to enable or disable the retraction and “Retraction Speed” and “Retraction Distance” will allow you to fine tune your retraction for the best results. “Z-Hop When Retracted” will separate the print head from the current layer whenever there’s a retraction to lower the risk of pushing the print and detaching it from the printing bed.

Picture by Lévi PONSARD

8. Cooling:

With “Enable Print Cooling” activated, you’ll activate the fan to blow onto the filament as it’s coming out. That cooling is very important to make sure the filament doesn’t stay melted for too long and start to bend down, especially for parts that are overhang. “Fan Speed” will simply control the speed of that fan in a percentage of its max speed. In the hidden settings, you’ll find “Initial Fan Speed” as well as “Regular Fan Speed at Height”. This allows you to set a lower fan speed at the start of the print then set the height where it’ll slowly ramp up to the regular speed. The melted plastic will have an easier time sticking with the printing bed. That’s why that initial fan speed is set to 0% as the default value.

9. Support:

As talked about in the recommended settings, “Generate Support” will try to generate support under the overhang part of the model if there is enough space for them. What’s going to be considered an overhang surface can be set with the “Support Overhang Angle”. At 0°, any slanted surface will be counted as overhang while at 90°, no surface will. The default value of 45° is a pretty safe place to keep this value. You can choose to give it a slightly higher value to reduce the amount of supports that will be printed for parts that do not really need those supports. I’d suggest keeping this value in-between 40 and 70° at a maximum. As you can see, 90° won’t even consider the top surface to be an overhang. Using this value would be the same as deactivating the supports altogether.

Support Structure” gives you a choice between two kinds of structure the supports will be generated, “Normal” or “Tree”. Normal will simply position the support structure right under the overhang surfaces then go straight up to them. Tree will start the base of the support not directly under the overhang surface then slowly lean until it’s under it.

As you can see, the normal support structure will start on the model, right under the roof but the tree support structure will start from the printing bed on this example. That is the biggest advantage of the tree structure, since supports can leave some traces where they were printed. Having to print supports directly on the model can lower the quality on those surfaces. By having the supports start from the printing bed instead, you can avoid it.

However, the structure isn’t always as solid as the normal one as it needs to slowly lean instead of staying straight. It can also use more material or take longer but this part will heavily depend on the model itself. I would suggest to use the tree structure only for models where you want the best visual quality, like a figure or statue and keep the normal structure for the rest.

Talking about generating supports on top of the model itself, the option “Support Placement” will allow you to set it so only support touching the printing bed will be generated or if they can be generated everywhere. Support Z-Distance” as well as “Support X/Y Distance”, set the gap between the model and the support structure. Since both the model and the supports are printed in the same material, printing them right against each other would result in the supports merging with the model itself. You’ll need this gap so the supports can be removed after the print is done.

Support Roof Density” will change the density at the top of the support. If the value is increased, that top structure will be more dense which can increase the quality under the overhang surface while also increasing the contact between the support and the model, which increases the risk of the two parts sticking to each other.

Practical Tip
This is always going to be a balancing act between well supported overhangs so they can be printed correctly and how easy the supports will be to remove. As with every one of these settings, I’d suggest starting from the default value and then slightly make the gaps smaller if the overhang isn’t being printed well and slightly make the gap bigger if the supports are sticking to the model too much.

10. Build Plate Adhesion:
The “Build Plate Adhesion Type” setting will allow you to select between no adhesions or the 3 types of adhesions with: 

  • None 
  • Skirt
  • Brim
  • Raft

Here’s what they all look like:

The option “None” won’t add any extra material to the print. This will both make the print faster and use less filament than using any other adhesion type. However, this should be used only if you’re sure your printing bed is levelled and that the first layer of your print has surfaces large enough to stick the whole model to the printing bed.

With a “Skirt”, the printer will first print a few lines around your model. As these lines are not connected to the model itself, they won’t help it stick to the printing bed. Their only purpose is to check if the printing is starting correctly and the printing bed is well levelled all around your model. You can set the distance the line is from the model with “Skirt Distance” and the number of lines it’ll print with “Skirt Line Count”.

Brim” will however, be a printer around the first layer of your model, which means this brim will be fused with your model and greatly increase the adhesion with the printing bed as the surface area of the first layer is increased. You will need to cut it off the model after it’s printed and it can leave some traces on the edges. Both “Brim Width” and “Brim Line Count” will set how large that brim needs to be around the model.

Practical Tip
This is the option I would suggest for most cases where the model needs extra adhesion as it doesn’t extend the duration of the print too much and also doesn't use that much extra material. However, since that brim will need to be cut from the model, it can add an extra step of post-processing.

A “Raft” will actually elevate our model and print a structure under all of it. This can have several benefits with an adhesion as good as with a brim but without having extra material to cut from the model. However it’s also the option that will add the most time to the print as well as use the most material. The first layer can also be less smooth as it won’t be printed against the flat printing bed.
Raft Extra Margin” is how much bigger the raft will be compared to the first layer of the model, it’s similar to the brim width.
Raft Air Gap” is the distance in-between the model and the raft. Same as for supports, if the model is printed right on top of the raft, the filament will fuse with that layer and both the raft and the model will be a single piece. You’ll need an air gap here so the model can be separated from the raft. A small air gap will make it harder to detach the pieces but gives you a first layer with better quality. A big air gap will make it easier to detach the pieces but also give you a first layer of worse quality and also risk the model to detach by itself during the print.
Raft Top Layers” is the number of layers at the top of the raft. These layers are fully filled in to create a smooth surface for the model. The more layers you’ll add, the smoother that surface will be and the smoother the model’s first layer will be. While 2 layers here will be much smoother than 1, adding more than that will have a very diminishing return while also adding a lot of extra print time and material used.

11. Dual Extrusion:
The dual extrusion settings are specific settings that can be changed if you’re working with a printer that has two printing heads instead of one. This part won’t be covered in detail here as these are more advanced uses that only matter for a few printers.

12. Mesh Fixes:
The mesh fixes options are fixes you can add to your model if it has some issues such as holes, intersections, empty layers or disconnected faces. These won’t be needed if your model has been created correctly. 

13. Special Modes:
The special modes have some modes that can be used such as the “Print Sequence” that will allow you to switch between printing every model at once to each model separately. In a normal print sequence, the printer will print layer by layer while printing every model at once. This option can allow you to fully print each specific model one at a time instead. Doing so can have some advantages but it also has a lot of constraints to respect. Do not use this mode if you’re not sure of what you’re doing. Such as having some models finished if the print fails halfway through and saving on some print time as the head doesn’t constantly need to move in-between all the models for each layer.  The main constraint is, since your printer head will need to lower back to print other models, you have to make sure no part of the printer will bump into the already printed objects.

There’s also the “Mould” mode which will, instead of printing the model itself, will print it as a mould that can be casted after to obtain the original model. There’s plenty of other special modes I invite you to look at all the hidden options to know they’re there in case you ever need to use any of them.

14. Experimental:

The experimental category has, as his name indicates, experimental features. These are usually more advanced ones that sometimes are not fully well supported so these also won’t be explained here. As usual, you should take a look in the hidden options to scroll through all of these to see if there’s anything that could be interesting for your use-case. The next step is now to slice our model. Now that we’ve gone through every important printing option, we can slice our model. This step is fully automated, Cura will take all our settings, slice the model and create the tool path accordingly. However it’s a good idea to review the layers after the slicing to spot any mistakes and then change settings to fix it.

Practical Tip
It can take a few tries of going back to the settings, slicing and checking again but it’s a lot better than starting a several hour’s print that has an obvious flaw 6 hours into the print.

To slice the model, simply click on the bottom right button “Slice”. This process can take a while depending on the size and complexity of your model and your processor’s power. After it’s done, you’ll get an estimate on the print duration as well as the quantity of material used for the whole print in grams and metres of filament. As well as the possibility to save the print file to the disk or a removable disk. You can also look at the “Preview” of the print. After clicking on the preview, you can see that the operation step at the top switched from “PREPARE” to “PREVIEW”. You can also see that some of the main tools have changed and the appearance of your 3D model is completely different.

Important
Always look at the preview of your print. It doesn’t take too long to check your preview while there are many possible problems you might not be able to spot if you’re not doing that simple and quick step.

The first option in the main tools, “view type”, allows you to switch between a layer view of your model and an X-Ray view. The X-Ray can be a nice way to see details, holes and overlaps on your model but the one that interests us right now is the layer view. With the layer view, you’ll be able to observe your print, layer by layer and spot if there would be any possible problem even before printing it. The next option, “colour scheme”, can give you a lot of different types of information directly through the preview of the model.

I’m going to keep the colour scheme on “Line Type”, as it allows me to easily see how each part of the model is considered which makes it easier to know which settings I need to change. As you can see on the list under, each part of the print has a specific colour attached. So when you look at your model, you know what the individual parts are. On the right side of the 3D view, a new slide has appeared with a number at the top. This slider allows you to go through every single layer of your print. It is very useful to start the preview at the bottom and slowly move the slider up. This way it often becomes very clear when something has a problem being printed. Especially with overhangs.

Practical Tip
As well as sliding the slider up and down, you can write down the exact layer in the box. There’s also a 3rd way to navigate in-between layers. When you’ve clicked in the small box with the layer’s number, you can press the up and down arrow on your keyboard to go up or down a single layer. This is a very useful way to precisely navigate between each layer.

Talking about overhangs, as it was stated earlier, it’s not because a surface is deemed overhang by Cura that it won’t be able to be printed. If the surface slowly leans away, the previous layers will give some kind of support and allow the next layers to be printed. This is why you can sometimes go pretty high on the angles that are considered overhang. Going past 60 or 70° will start to be a lot more problematic.

Another way to also print an overhang surface is if this surface creates what’s called a “bridge”. A bridge, in this context, means that the surface will have a start and an end point that are supported with a flat overhang surface in the middle.

With a bridge, the printer will be able to print from one point to the other. Since the filament is being cooled by a fan as it’s coming out, it can stay pretty straight as long as the bridge is not too long. How big of a bridge you can print before the filament starts to bend down is going to depend on the printer itself as well as your printing settings but also the specific filament you’re using.

Practical Tip

You can find calibration pieces online that will allow you to fine tune your printer and settings so you can get the best results possible out of it but also learn its limits. Here’s a popular file to test several parts. I’d suggest starting by printing some of these calibration files and referring to the troubleshooting part of this unit to see where the mistakes can come from and how to fix them.

Not only can you proceed layer by layer, but you can also play back the exact path of the printhead and preview the printing process. To see it, you can press the play button at the bottom or move around the timeline of that particular layer with the slider. It can be useful to see the exact path of the printer head for very specific tasks like looking at the order in which some lines are being printed.

The last menu in the main tools let you go back to the printing settings. If you’ve spotted anything that needs to be corrected, you can change it. Any change will force you to slice your model again if you desire to see the preview or export the file.

Talking about exporting the file, once you’ve made sure the printing process is correct. The last thing to change is the name of the file, or at least take note of it. The name of your file is located at the bottom left of Cura.

By default, Cura will start the name of the file with the name of the printer. “CE3PRO” for “Creality3D Ender 3 Pro”. Then the name of the file that we imported, separated by an underscore. You can simply click on the name if you desire to change it and write the new name. It can be useful to add a version number for each iteration of the same file to easily differentiate them. 

Once everything is in order. You’ll finally be able to save your printing file or send it directly to the printer if it’s connected to the network. If any external storage is connected, Cura will give you the option to directly save onto that external storage without having to open the directory. You can even choose to directly eject the external storage after the file has been saved. These shortcuts are very useful and make this operation very fast so I’d suggest using them if your printer isn’t connected to the network.

Remember
Let’s go back over each steps to remember them:

1. Selecting/adding the right printer
2. Selecting the right nozzle size
3. Selecting the right filament
4. Importing the 3D design
5. Positioning, resizing and rotating it correctly.
6. Editing the desired print settings 
7. Slicing the model
8. Checking the preview for any issues and changing settings if needed
9. Naming the file correctly
10. Saving the file or sending it to the printer

Setting up the Machine

Picture by Lévi PONSARD

In this part you’ll learn how to prepare the FDM printer and start your print.

Now that we’ve created a file, we can send it to the 3D printer. However, before starting the print, there’s a few things to make sure are set up correctly. As said earlier, we’ll be using a Creality3D Ender 3 PRO for these explanations. Here’s most of its main components named:

Pictures by Lévi PONSARD
Picture by Lévi PONSARD

This particular Ender 3 Pro has been modified with a glass bed instead of the original printing bed. This can allow for a smoother first layer but might need slightly higher printing bed temperature as the thick glass sheet won’t conduct heat as well as the original bed. Now that we’ve gotten more familiar with the printer, let’s start it by switching the power button. After turning on the power, the screen should turn on and after a few seconds greet you with the info screen.

Picture by Lévi PONSARD

This screen will give you some of the main information like the temperature of the nozzle and the printing bed, as well as the position of the printhead on each axis. Most printers will give you some kind of info screen when they’re started up. If not, they’ll probably be a few clicks away. To control the menu, you can use the knob next to the screen. Some printers will have buttons instead or even a touchscreen. Clockwise rotations to go down in the menus, and anti-clockwise to up in the menus. To select an option, you’ll need to press down on the knob itself. Clicking on the knob while on the info screen will get you to the main menu.

From here, you can navigate between all sorts of useful menus, here’s a small explanation for each of those. The option at the very top will always be the way to go back up one menu, this is why it’s called “Info Screen” here and you can see an arrow going up next to the option. Selecting this will just bring you back to the info screen. The actual first option in the main menu is “Prepare”. In that prepare menu, you’ll be able to move each of the axes, reset the position to home, disable the steppers motors or even preheat the printhead and printing bed. Next we have the “Control” menu, this one will allow you to control different parameters such as the temperature and speed directly on the printer itself. You can use these to override what was selected on the slicing software in case of needs. Print from TF”, as its name indicates, will allow you to start a print from the micro SD card plugged in the printer. We’ll first need to make sure the printer is ready before actually starting a print. Change TF card” will allow you to change between different micro SD cards.

Definition
TF card: As you’ve probably noticed, these menus are using “TF card” instead of “micro SD card”. This is, in short, the original name that was given to micro SD cards. It stands for TransFlash.

The last option, that’ll you need to scroll down to see, is “About Printer”. That’ll give you information about your printer and the version of the firmware installed. The first and main thing to prepare on our printer is the printing bed, this one needs to be clean, levelled and at the right height. To clean the printing bed, simply remove anything that’s sitting on it. If some parts are stuck on the bed itself and it needs more specific cleaning, refer to the Maintenance chapter.

The reason why the print bed needs to be levelled is quite simple: if it is not levelled, the filament is sometimes placed too high from the print bed, resulting in poor adhesion. While at other times, the printer head will be too close to the printing bed and the first layer will suffer from it. Here’s an example of a badly levelled bed, as you can see the filament is sometimes too far away from the bed and sometimes too close:

It’s even possible, in extreme cases, where the nozzle can be in contact with the printing bed itself. This can damage the printer itself. Making sure this is not the case with a correctly levelled printing bed is very important.

On top of the bed being levelled, it also needs to be at the right height. If it’s too low compared to the nozzle, the first layer won’t have great adhesion and the print will be very likely to get detached and give you a failed print.
On the other hand, if the printing bed is too high so it’s too close to the nozzle means the first layer will be squished down, this will reduce the quality of the print and can be one of the reason you get what’s called “elephant foots” which will be talked more in details in the 6th chapter, Troubleshooting.

Here’s how it would look on an actual print:

Picture by Lévi PONSARD

Now that we know why the bed’s level and position is important, let’s actually carry it out.

Practical Tip

Auto-levelling: Some 3D printers will have some form of auto levelling options, usually helped by some kind of sensor to measure precisely the position of the printing bed. Then this information is then given to you to adjust it manually or the printer will actually take those differences into account when printing. Some 3D printers also simply have an option in their menu that’ll give you a step by step guide on each step you need to do to level your bed. However, this learning material shows how to manually perform the individual steps for the simplest printers that do not have these fancy levelling options. If your particular printer does have auto-levelling options, I’d invite you to use them. But reading each of these steps is still very important to understand the inner workings behind bed levelling.

The first step is going to get the printing head on its home position. This way the nozzle will be at its starting position for a print, which will allow us to level the printing bed from there. To get the printing head to its home position, navigate from the “main” menu to the “prepare” menu then select “Auto Home”. When selected, the printer should reset its position automatically on each axis.

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For the next step, you’ll have to be able to move on the X and Y axis freely. While you could use the menu to move them around as needed, this would take a lot longer than the alternative. Instead, you can disable the stepper motors. While enabled, the stepper motors won’t allow you to freely move the printing head around. To disable them, navigate in the “prepare” menu then select “Disable steppers

When that’s selected, you’ll be able to move the X and Y axis, which on this printer, means moving the printing head left and right and the printing bed back and forth.

Pictures by Lévi PONSARD

Picture by Lévi PONSARD

Now that we can move the printing head around the whole printing bed, let’s grab a piece of paper and start the levelling process. A normal printing piece of paper should work, such as 80gr/m2, as long as it’s not especially thin or thick as it serves to check how far the nozzle is from the printing bed. The printer should have 3 or 4 knobs under the printing bed to precisely level the bed. Position the head on top of one of the knobs and slide the piece of paper in-between the nozzle and the printing bed.

Picture by Lévi PONSARD

You can now test the height of that specific spot by sliding the piece of paper back and forth. If the piece is sliding without any resistance, the nozzle is too far away from the printing bed, you can turn the knob under that spot to push the printing bed higher up. On the other hand, if the piece of paper is stuck under the nozzle and can’t slide anymore, the nozzle is too close to the printing bed and you’ll need to turn the knob the other way around to lower the printing bed. The right amount of resistance on the piece of paper is pretty low. It’s not easy to get it from just a text explanation but the most important part of this is mostly to have each corner at exact same resistance so the printing bed is at least levelled. If the bed is well levelled but slightly at the wrong height, you can add an offset when printing to correct for it.

Practical Tip
Printing files for bed levelling You’ll be able to find bed levelling files online such as this one. You can also create a similar file yourself with any 3D modelling software, they’re usually very simple. When you print something like this, you have to check how the line is printed and at the same time adjust the knobs under the printing bed. Repeat this until the 1st layer has the perfect height.

Important
Since you won’t have to level your bed too often, making sure it’s as levelled as it can be is definitely worth going all the way to using bed levelling files. A well levelled bed will make your life so much easier.

To print anything we’ll need some filament. If another filament is already placed in the printer, we’ll first need to remove it to place the new one.  If not, you can skip this part but you’ll always end up having to do it at some point so read it carefully.

Important
Don’t forget the filament you’re going to place in the printer matches the one you selected in your slicing software.

Once again, a lot of printers will have a step by step function to do the filament change. You should use that function if it’s available. Below you will find the steps to manually change it, if your printer cannot do it automatically. The first step, to either remove or to add filament, will be to heat up the printer’s head. As the filament has cooled down inside the printer’s head, it’ll be stuck in there. You’ll need to heat up the printer’s head enough to melt the plastic to be able to remove it. To heat up the printer’s head, you can either go from the “main” menu to “prepare” then “preheat PLA or ABS” then select the “END” option as you only need to heat up the printer’s head and not the printing bed.

You can also manually set the exact temperature you want the nozzle to be from the menu “Control” to “Temperature” to “Nozzle” and spin the knob to change the value.

Once you go back to the info screen, you’ll see the set temperature for the nozzle has changed. The printer will now heat up to reach that set temperature.

Important
Burn danger: As the nozzle starts to heat up, it’ll reach dangerous temperatures very fast. Make sure you do not touch the nozzle or let the machine unattended.

Picture by Lévi PONSARD

When the nozzle has reached the asked temperature, the plastic inside the printer’s head will have started to melt. It’ll now be possible to remove it. However some of the plastic will still be stuck inside. This is not a problem but something we’ll have to keep in mind later. To remove the filament, you could go in the move axis menu and turn the extruder in negative values until it has removed the whole filament, but doing so will take a pretty long time on a Bowden extruder. On a direct drive extruder, you’ll probably be forced to do it that way but it won’t take too long as the filament doesn’t have a long travel between the printer’s head and the extruder. The quicker way, if you are using a Bowden extruder, is to loosen the extruder and simply pull it out.

Make sure you turn the roll so the filament doesn’t hang around as it could make it likely to create some knot within the roll and create issues with the next prints.

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Once the filament has been fully removed it’s also important to block the end of the filament for the same reason that was just mentioned. Most rolls will have holes for this purpose. You can also use a small filament clip.

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To ensure a good longevity of your filaments, they should be stored in place as dry as possible as humidity will decrease the quality of your prints by a lot. It’s also possible to dry them out if they ever get humid. A food drier can do the job very well. After the previous filament has been removed and stored correctly, we can now install the desired filament roll. Once again, this operation can have a guided setup built in the machine you’re using. I’ll invite you to use this one if available. If not, I’ll describe again, each of the steps needed to accomplish this task.

The first step, as said earlier, is to heat up the nozzle. You can refer back on how to do so for the ender 3 pro at the start of the removing filament explanation.

While the nozzle is heating up, you can already prepare the next roll to gain time. The first thing to check is the end of the filament, it’ll need to be cut straight.

Pictures by Lévi PONSARD

Practical Tip
It can sometimes be easier to cut the end bit of filament at an angle to make the next operation of inserting the filament in the extruder easier. I’d also suggest trying to straighten a few centimetres of filament as it’ll probably be slightly bent which will make the next operation a lot harder.

The roll can usually be placed in two different ways. It’s a good idea to look at the travel the filament will have to make from each way and choose the one that’ll give the smoother travel and the less stress on the filament.

    Pictures by Lévi PONSARD

Next, we’ll need to move the filament into the extruder. This operation is different between Bowden extruders and direct drive ones.

For a Bowden extruder, you’ll need to unclamp the extruder again to insert the filament through the extruder and then in the Bowden tube. This operation can be really precise as the filament needs to line up with the entrance of the Bowden tube. Once you’ve reached the printer’s head with the filament, don’t push it more. It’s better to let the machine do the last bit than pushing it yourself as you risk pushing it with too much force and jamming the filament.

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For a direct drive extruder, you’ll need to insert the material until it is right against the extruder then make the extruder move while making sure the filament is being grabbed. To move the extruder, you can go back to the prepare menu, navigate to move axis and move the extruder until you can see the material coming out.

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As said earlier, there’s still a little bit of plastic from the previous filament left in the printer’s head. To clean it off, you’ll need to extrude material until you can see the new colour appear. Once the filament is of the right colour, you can cut it out near the nozzle and the printer should be ready to print.

While the printer should be ready to print now, we’ll talk about an extra step that can help with the first layer adhesion. If the bed is perfectly levelled and at the right height, the adhesion shouldn’t be too much of a problem. However, on a surface like glass, it can still be hard to get the print to stick to the printing bed. To help with that task, there are a few types of coating you can use on your bed such as hairspray, glue stick or specialised sprays. I’ll use hairspray in this example as it’s a pretty cheap solution that will be easy to find anywhere compared to the specialised ones. Glass beds are often the ones that need to have added coating as they’re really smooth on the surface, most other bed surfaces will be rougher and won’t need that extra coating. The hairspray should be applied every 2 to 6 prints. Spray an even coat over the printing bed and let it sit for a minute. You can wipe off the excess with a paper towel but do not remove the actual coating.

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Let’s now finally start our print. To do so, we’ll need to navigate from the main menu to “Print from TF” and select the right file.

Once the file is selected, the printing bed and printer’s head will heat up to the desired temperature and the print will start.

I would highly suggest observing the first layer very closely as it is being printed. It’s better to stop the print early on if there is an issue than letting it run all the way and fail the print and risk damaging the printer. Here’s what a good first layer should look like.

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If the first layer is good and is stuck to the printing bed, you don’t have to keep an eye on the printer at all times. It’s advised to still come every now and then to check on the print in case anything goes wrong.

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If the print doesn’t simply pop out when you try to grab it, there’s several techniques to use to remove it. Waiting for the printing bed to cool down should make it much easier to remove. One of the most common ones is to use some kind of scraping tool to get under the print and detach it from under it.

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If you’re using a bendable printing bed like the original Ender 3 pro printing bed, you can simply remove the printing bed and bend it down, the print should pop out by itself. Don’t forget to clean the printing bed for the next print.

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Post-Processing

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In this part you’ll learn how to go from the printed parts to a finished part by removing supports, assembling pieces and coating the pieces.

One of the first steps you’ll often have to do on a print is to remove the support structure. Depending on the specific print, this operation can be very delicate. You can use a set of pliers, cutter and cutting pliers to help you with this process.

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After removing the supports there might still be some extra material on your print such as seams or stringing. To avoid these problems in the first place you can check the troubleshooting chapter.

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You can smooth out those extra bits with sandpaper or even use a heat gun for the stringing. Be careful to not keep the print too close or for too long under the heat gun as it’ll start to melt the actual print.

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Some pieces might also need to be assembled. If you need to use glue, make sure to use glue that works with the specific kind of filament you’re using. Such as cyanoacrylate or superglue.

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If two pieces need to fit together, you might realise that printed parts aren’t always 100% accurate in size. This means you might have some difficulties fitting pieces together if the margins were very small. This part should be thought of in the designing part. However if the pieces don’t fit after being printed, there’s still ways to make them fit and not have to print a new model. You can sand the parts that need to fit together until they do.

Pictures by Lévi PONSARD
Picture by Lévi PONSARD

Or you can also heat up one of the pieces to make it softer and force them together. To do so you can put the end bit in boiling water for around 5 seconds then press the parts together before it cooldown. Another way to eat up the piece would be through the use of a heat gun, however do not use actual fire to heat up your part as you’ll burn the plastic as well as being very dangerous. The last post-processing step is more of an appearance one. Prints that come out of an FDM 3D printer will have visible layers. It’s possible to smooth out the print through different means. If you’re printing with ABS or ASA, you’ll have the option to use acetone to smooth out your prints. While there are solvents for other materials that can be used for chemical smoothing, these can be quite dangerous, which is why we will only focus on acetone smoothing in this course.

Important
Wear adequate protective equipment: Acetone is a dangerous chemical and as such you should be wearing adequate hand and eye protection as well as being very careful when you handle that chemical. Use latex or neoprene gloves.

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Now that we’re mindful of the risk and security measures to work with acetone, let’s actually use it to smooth our print. Make sure you don’t pour the acetone directly on the print as it would dissolve it. Instead, you can pour a little bit on a paper towel then place that wet towel inside a bowl that’s bigger than your print and also resistant to acetone like FEP, TFE, PFA or polypropylene plastic.

Once that’s done, you can place it over your print. The fumes themselves coming out of the paper towel will be enough to smooth the print evenly. You can leave the print from 10 to 30 minutes in there depending on how much you desire to smooth it out. Keeping the print there for too long can start making small details disappear.

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Since not every type of plastic reacts to acetone, there’s another way to smooth out your print. You can obviously use sand paper for this effect, the smaller the grain, the smoother it’ll be. You can also add some smooth resin coating like XTC-3D, this can have great results on any kind of surface but be careful that it’ll be adding an extra thin layer and that very small details can kind of disappear the same as with acetone smoothing.

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As well as smoothing, you might also want to paint your prints. It’s even possible to use this step as a way to smooth them out by sanding the print in-between coats of paints. You should start by using one or two layers of primer paint. You can use different levels of thickness for your needs. A thicker primer will allow you to fill in the layer gaps better but will also add a thicker layer on your print. Don’t forget to choose a primer that is compatible with plastic.

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For better results, you’ll want to sand the print in-between layers of paint. After the layers of primer are applied and dry, you can paint the model. Using paint from the same brand will ensure a better adhesion of the paint on the primer.

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Troubleshooting

In this part you’ll learn how to spot the different issues that can occur on your print or your printer and learn how to fix them.

Since FDM 3D printing uses a lot of moving parts, figuratively as well as literally, there are a lot of things that can go wrong when 3D printing. This part will give you a non-exhaustive list for the most common issues that can occur on your print or the printer itself as well as how you can fix the problem. You do not need to read through all of this right now. This should be more used to troubleshoot your printing issues when you start to see them appear. I’ll divide this part into two sub-parts, the first will be about issues that can be spotted on your print itself and the second one for issues on the printer.

Printing issues:

  • First layer doesn’t stick to the printing bed
  • Corners at the bottom warp
  • Not enough filament come out, Under-Extrusion
  • Too much filament come out, Over-Extrusion
  • Stringing appears on your prints
  • Elephant’s foot appear at the bottom of your print
  • Some layers are shifting in the middle of your print
  • Some layers are separating in the middle of your print
  • The bridges are of poor quality
  • Poor surface under the supports
  • The supports are failing
  • Blobs and zits appear on the print

Printer issues:

  • Filament doesn’t come out of the nozzle
  • The filament is grinded
  • A blob of plastic formed around the nozzle
  • Extruder or the other motors are making weird noise
  • The nozzle is smoking

Let’s start with the printing issues.

First layer doesn’t stick to the printing bed

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As talked about previously in detail, the first layer is of the utmost importance. Here’s the step you can look into in case your first layer isn’t sticking to the printing bed:

  • Level your printing bed
    This is the main one to check, if your printing bed isn’t levelled correctly, nothing else you’ll try to do will work. You can refer back to LO5 for the bed levelling instructions. You can also very slightly lower the printing head so it’s closer to the printing bed. Be careful to only very slightly adjust it as you do not want to be too close to the printing bed.
  • Use a heated printing bed
    If your 3D printer is equipped with a heated printing bed, the first layer adhesion is going to be an easier task. A heated bed will slow down the cooling of the filament as it’s being extruded. A filament that would cooldown too fast will shrink faster and detach itself from the bed easier. Which will be the case on a non-heated bed. Some types of filament, like ABS, will imperatively need a heated printing bed to be able to be printed at all for these reasons.
  • Add a brim or raft to your print
    As we’ve seen before, adding a brim or a raft to the settings of your print can help first layer adhesion as a bigger area will be in contact with the printing bed.
  • Use coating on the printing bed
    We’ve also seen the use of hair spray or glue stick for better adhesion in LO5.
  • Use an enclosure to preserve heat
    Same as for the heated bed, an enclosure will allow the extruded filament to cooldown much slower as it’s isolated and can keep a much higher temperature. It can also protect from wind.
  • Lower or disable fan cooling on first layer
    Same reasons as for the other part talking about heat, you can lower or even completely disable the fan cooling on the initial layer to help it stick.
  • Increase the flowrate on the initial layer
    By increasing the flowrate on the initial layer, more plastic will be pushed out of the nozzle and will more likely get squished and attached to the printing bed. However, doing this might increase other issues such as over-extrusion and elephant’s foot so this should only be used as a last resort solution or if those issues are not a problem for your final piece. This setting can be found as “Initial Layer Flow” on Cura. Only increase it by 3-6% to limit these other problems
  • If all else fails, use tape on the printed brim or raft
    When everything else has been tried and tuned well but you’re not able to get your print to stick, there’s still one thing that you can do that can help you keep almost any print to stick to the printing bed. If you’re using a brim or a raft, you can pause your print after those have been printed and use a strong adhesive tape to stick that brim or that raft to the printing bed.

Corners at the bottom warp

Picture from Simplify3d

Warping happens when the previous layers that were printed on the printed bed have already cooled down and the new layers printed on top start to cool down and shrink themselves. Because the new layers are fussed with the previous ones, when they try to shrink themselves from cooling down, they’re not able to move freely because of the previously already cooled down layers. So to be able to shrink, they’ll curl up the previous layers. As the layers get bigger, the previous layers have time to cool down more and the shrinking dimensions also get longer. Here’s how you can alleviate this issue:

  • Use a heated printing bed
    If your 3D printer is equipped with a heated printing bed, the first layer adhesion is going to be an easier task. A heated bed will slow down the cooling of the filament as it’s being extruded. A filament that would cooldown too fast will shrink faster and worsen warping issues.
  • Lower or disable fan cooling on first layer
    Same reasons as for the other part talking about heat, you can lower or even completely disable the fan cooling on the start of the print.
  • Use an enclosure to preserve heat
    Same as for the heated bed, an enclosure will allow the extruded filament to cooldown much slower as it’s isolated and can keep a much higher temperature. It can also protect from wind.
  • Add a brim or raft to your print
    Brims and rafts can also help with warping as they’ll act as a buffer on the extremities of your print.
  • Design pieces with warping in mind
    Since larger areas are prone to warping more, the pieces can be designed to have less of these, one way to do this is to cut small lines on a large surface for the first few layers to have several smaller areas instead of one large one.

Not enough filament come out, Under-Extrusion

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Under extrusion can result in weak prints, bad first layer adhesion or even fully failed print. There’s multiple reasons it can happen, here’s what you should look at to avoid under-extrusion, and these are actually the same as for over-extrusion:

  • Verify the filament diameter
    Make sure you’re using the same filament diameter that your printer is set to be used with as well as what is set on the slicer software. If all those settings and the filaments don’t match, you’ll have extrusion issues.
  • Verify the nozzle diameter
    Same as with the filament diameter, make sure the nozzle’s diameter is the same on the slicer setting as the one that is installed physically on the printer. Having a different nozzle diameter in the slicer settings will result in extrusion issues.
  • Increase the flowrate on the slicer
    If the nozzle and filament diameters are all set correctly, the next step you can take is to increase the flow rate multiplier on percentage. On Cura you can change the “flow” that is normally set to 100%, I’d suggest slowly going up by increment of a few percentages and do different testing.
  • Calibrate the extruder’s Esteps
    If you always have to increase the flow rate on all filament you try, this isn’t a good permanent solution and it means the extruder’s Esteps aren’t calibrated correctly on your printer. You should calibrate them so you do not need to change the flow on every print. This operation will be specific for each printer so I’ll let you search how to do it on the specific printer you’re using.

Too much filament come out, Over-Extrusion

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Over extrusion can result in bad quality prints or even clogged nozzles if the filament doesn’t have anywhere to go. There’s multiple reasons it can happen, here’s what you should look at to avoid over-extrusion, and these are actually the same as for under-extrusion:

  • Verify the filament diameter
    Make sure you’re using the same filament diameter that your printer is set to be used with as well as what is set on the slicer software. If all those settings and the filaments don’t match, you’ll have extrusion issues.
  • Verify the nozzle diameter
    Same as with the filament diameter, make sure the nozzle’s diameter is the same on the slicer setting as the one that is installed physically on the printer. Having a different nozzle diameter in the slicer settings will result in extrusion issues.
  • Decrease the flowrate on the slicer
    If the nozzle and filament diameters are all set correctly, the next step you can take is to decrease the flow rate multiplier on percentage. On Cura you can change the “flow” that is normally set to 100%, I’d suggest slowly going down by increment of a few percentages and do different testing.
  • Calibrate the extruder’s Esteps
    If you always have to decrease the flow rate on all filament you try, this isn’t a good permanent solution and it means the extruder’s Esteps aren’t calibrated correctly on your printer. You should calibrate them so you do not need to change the flow on every print. This operation will be specific for each printer so I’ll let you search how to do it for the printer you’re using.

Stringing appears on your prints

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Stringing are the smallest lines of filament that appear in between different parts of our model. They occur when the nozzle has to move from one printed area to another on the same layer. When the printer has finished printing an area, the extruder will stop pushing materials out, however some material will still melt and come out of the nozzle as it’s moving, creating the stringing.

  • Change the retraction settings
    The retraction, if activated, will actually turn the extruder backward to retract some of the material every time the printer has finished an area. That way the material doesn’t have as much time to melt and create stringing. You can use the “Retraction Distance” and “Retraction Speed” settings to modify how much and how quickly the retraction happens, both settings usually need to be boosted if you’re having bad stringing issues.
  • Lower the printing temperature
    Since the stringing is due to the filament melting. Using a lower printing temperature can help diminish the amount of stringing. Do not go lower than the specification of the filament you’re using as printing too low will also create other issues.
  • Use a direct drive extruder
    Because the extruder is much closer on a direct drive extruder, the retraction will be a lot more efficient and also don’t need to move as much. Using a printer with a direct drive extruder will usually result in much lower stringing.
  • Use less flexible filament
    On top of the distance between the extruder and the nozzle, the flexibility of the material will have a huge impact on stringing as it’ll stretch a lot more as it’s being retracted instead of moving away from the nozzle.
  • Clean the nozzle before the print
    Another reason for stringing can be a small layer of filament that got stuck on the nozzle from previous prints. When the nozzle heats up again, that layer will melt and can attach to the next print. You should always clean the nozzle of your printer while it’s hot, before printing. You can use a brass brush for this.
  • Use a heat gun to remove the stringing
    As talked about in the LO 5:Post-processing, you can also remove the stringing after the print with a heat gun.

Elephant’s foot appear at the bottom of your print

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An elephant’s foot on a print is when the first layer is slightly bigger than the rest of the print, making the print’s dimension incorrect. The next few layers then slowly move back to the original size. It happens when the first layer is getting squished onto the printing bed. The filament then has to stretch itself to the sides, creating the elephant’s foot.

  • Increase the distance in-between the printing bed and nozzle
    By lowering the bed away from the nozzle, you’ll reduce how much the filament needs to stretch at the risk of reducing bed adhesion.
  • Lower the printing bed temperature
    Lowering the printing bed temperature can also help the filament not stretch as much at the risk of reducing bed adhesion.
  • Use anti-Elephant’s foot slicer settings
    Some slicers will have specific settings to mitigate the elephant’s foot effect. In Cura, you can use a small negative value on “Initial Layer Horizontal Expansion” so the first layer is actually printed slightly smaller than it should be to compensate for the elephant’s foot.
  • Add a raft to your print
    A raft can completely remove the elephant’s foot effect as the first layer printed won’t be part of the actual part. This will however add extra time and material to the print.

Some layers are shifting in the middle of your print

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Layer shifting can be pretty obvious as you can see your model shifting on an axis somewhere in the print, either once or multiple times. It usually happens when either the Y-axis or the X-axis moves in an abnormal way.

  • Make sure each axis can move properly
    Verify if anything is blocking either the belt, the printing bed or the printer’s head, especially on the axis in which the layer shifting occurred.
  • Check your X-axis and Y-axis motors
    Make sure the motors are screwed tight to the printer and the pulleys are attached to the motor securely.
  • Check the belt’s tension
    If the belt’s tension isn’t correct, the pulley might skip a step on the belt and create a layer – shift. Check on your specific printer’s manual for this maintenance operation
  • Lubricate the bearing on the smooth rods
    The bearing on the smooth rods should be lubricated with soft grease or super-lube for a smooth movement if your printer is using smooth rods.

Some layers are separating in the middle of your print

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Layer separation is when some layers cleanly detach from previous ones. The reasons are the same as for warping. The layers cool down at different speeds and the shrinking force exceeds the layer adhesion. 

  • Lower the layer height
    If the layer height is too high for the nozzle diameter, the layer adhesion will be very weak. Don’t forget the maximum layer height is 75% of the nozzle diameter.
  • Increase the printing temperature
    Increasing the temperature can slow down the cooling of the filament and correct the layer separation issue
  • Lower fan cooling Same reasons as for the other part talking about heat, you can lower the fan cooling to reduce the cooling speed.
  • Use an enclosure to preserve heat
    Same as for fan cooling, an enclosure will allow the extruded filament to cool down much slower as it’s isolated and can keep a much higher temperature. It can also protect from wind.
  • Use a different filament
    Some filaments have a lower layer adhesion. If the problem persists after trying all the other solutions, a bad quality filament could be the culprit.

The bridges are of poor quality

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If you can see saggy lines under bridges, it probably means some of your bridge settings are not correctly set up or you’re trying to print a bridge too big.

  • Enable bridge settings
    For your slicer to use specific settings for bridges, you’ll usually need to activate them. On Cura, you can activate “Enable Bridge Settings” in the experimental category. Do some test prints with the default settings before starting to change them.
  • Increase the printing speed of bridges
    By increasing the speed at which the bridge is being printed the filament has less time to sag down. In Cura this is the “Bridge Skin Speed”.
  • Lower the flow rate for the first layer of bridges
    By slightly lowering the flowrate of filament, the filament will be more likely to have to stretch in a straight line and don’t have any extra filament to sag down with. In Cura, this is the “Bridge Skin Flow”
  • Increase cooling fan speed for bridges
    As cooling is increased, the filament has less time when it’s melted enough to start sagging under the bridge. This setting can be found as “Bridge Fan Speed” on Cura.
  • Use supports for long bridges
    For very long bridges, there’s usually no secret settings that will allow your printer to print them correctly. Using one or several supports to divide the longer bridge into a few smaller ones will help greatly.

Poor surface under the supports

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When looking at the surfaces directly on top of supports, you might get very poor results. This can happen because supports are normally set up to break apart easily from the print. Those settings can be adjusted to give better support.

  • Lower the gap between the supports and the model
    By default, supports are set to be really easy to remove from the print, this means the gap in-between the model and the supports is very large. This avoids the model to fuse with the supports but can be sometimes too large and means the model itself isn’t supported well enough so the first few layers printed on top will sag. You can lower the “Support Z Distance” setting in Cura but be wary that the closer it’ll be, the more likely the support will fuse with the model. This is, as always, a balancing act.
  • Increase support roof density
    The top of supports aren’t fully filled layers. This is once again to avoid support from sticking too much to the model. However, with a low density, the layers that will be printed on top won’t have as flat of an area to get printed on. You can increase the “Support Roof Density” setting in Cura but be wary that the denser it’ll be, the more likely the support will stick with the model. Same as the gap, this is a balancing act. You can also increase the “Support Interface Thickness” which will increase the amount of layers of this denser layer that is touching the model. This can make the roof of the supports slightly smoother in the cost of a slightly longer printing time and material use.
  • Use dual extrusion for different material supports
    If your printer is equipped with dual extrusion capacity. You can use a different material for the support structure. Some will make sure the supports do not stick as much as if it was printed all in the same material and some other material can also dissolve in water. This can be combined with making the gap between the model and the support very small as well as having a great support roof density so the surface on top of supports is printed perfectly while avoiding the fusing issue by printing in only one material.
  • Increase cooling fan speed
    As cooling is increased, the filament won’t have as much time to bend after being printed and won’t move as much from the initial printing path.
  • Rotate the model to avoid large overhang surfaces
    By rotating the model, you might be able to avoid large overhang areas. The bigger an overhang layer is, the more likely it’ll start having quality issues.

The supports are failing

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A failed support will be very visible on the final print as the support fell or broke, the overhang part won’t be printed correctly. Supports can have a tendency to break or detach from the printing bed as they’re a lot more fragile and often have a smaller area of contact on the printing bed.

  • Avoid isolated support towers
    An isolated support structure will be weaker and is then more likely to fail. By grouping supports close to each other, they’ll create a much stronger structure that’ll also stick to the printing bed better.
  • Add a brim to the support structure
    As well as being a weak structure, isolated support towers will have a very small area of contact with the printing bed. This will greatly lower the adhesion level of these supports onto the printing bed. By adding a brim to the support structure itself, you’ll greatly increase the adhesion of the smaller support structures and can avoid many failed supports.
  • Increase the support density
    Default settings for supports usually have a very low density to speed up their printing process as well as use less material. In some cases, it might be a good idea to slightly increase that density for stronger supports. You can use the setting “Support Density” in Cura to modify this. Make sure you also have one wall around the support in the “Support Wall Line Count” setting. This support wall will greatly increase the strength of the support structure.
  • Reduce printing speed for supports
    Same as for the support density, the printing speed for supports can be set higher than for the model itself. This speed can sometimes be problematic, especially when printing a thin support tower as it’ll get pushed around. You can lower the “Support Speed” setting in Cura if you need to print thin and weak support towers if the other solutions aren’t enough.

Blobs and zits appear on the print

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Blobs and zits are extra material coming out of your nozzle when there shouldn’t be any coming. They’ll create small blobs visible on the outside of the print, decreasing the overall quality and look. These can’t always be completely avoided but there’s a few settings you can look at in case they’re a big issue.

  • Enable retraction settings
    Since blobs and zits can be created from the extra material coming out of the nozzle at the end of a printed layer, enabling the retraction settings can be a great way to lower their impact. You can check the “Stringing” part for a more detailed explanation on those settings
  • Turn off Z-Hop
    “Z-hop” allows the printer to separate itself from the print to move to a different part while not printing. This can be very useful as it avoids the printer’s head bonking on the print itself and detaching it from the printing bed. However, this small gap between the nozzle and the print allows for some material to ooze out of the nozzle, creating blobs and zits. You can deactivate the option “Z-Hop When Retracted” on Cura to remove that step. 
  • Check for over-extrusion
    Another reason for the appearance of blobs and zits can simply be an over-extrusion. The filament could be pushed too much out of the nozzle and have nowhere to go but to the outside edge. If you’re experiencing a lot of blobs and zits on the walls of your print, it’s very likely due to over-extrusion. Check the “Over-extrusion” part to correct this.
  • Enable coasting
    The “Enable coasting” option, found in the experimental category, is another way to help with blobs and zits. This option will stop the extruder earlier at the end of a layer and let the oozing come out of the nozzle to finish the layer. This way, no extra material comes out after the layer is finished as it’s used itself to finish the layer. You can use the setting “Coasting Volume” to specify how early the printer should stop extruding by setting the amount of filament oozing out.
  • Dry up your filament
    If your filament absorbs a lot of moisture, a lot of issues can happen from this. One of these can be blobs and zits. As the moisture on the filament creates steam in the printer’s head, it’ll pop at random times and create blobs then dents on your print. To dry up your filament, you can use food driers of appropriate size and make sure they’re stored in a dry container to keep a great longevity of your filaments.

Now let’s look at issues that can occur on the printer itself

Filament doesn’t come out of the nozzle

Picture by Lévi PONSARD

A clogged nozzle or printer head can manifest itself through irregular extrusion or even no extrusions at all in the worst cases. It can also cause other issues like grinded filament. Let’s see what can cause a clogged nozzle and how to avoid it:

  • Clean your nozzle regularly
    Small debris of plastics have a tendency of getting stuck on the outside of the nozzle. These can build up and cause multiple problems. To clean your nozzle, you should first heat it up and use a wire brush.
  • Dry up your filament
    Moisture on your filament will give you irregular extrusion and could be the cause of clogging your nozzle. To dry up your filament, you can use food driers of appropriate size and make sure they’re stored in a dry container to keep a great longevity of your filaments.
  • Use better quality filament
    Lower quality filament can cause all sorts of problems, if everything else should be in order, you should try using a different brand of filament and see if the problem persists.
  • Don’t use a layer height too small
    Printing too close to the previous layer or to the bed can block the filament from coming out freely out of the nozzle. If it’s blocked, it can also create a clog in the nozzle or hot end.
  • Clear the gap between the Bowden/PTFE tube and the nozzle
    If clogged nozzles seem to happen frequently, this could be the culprit. The Bowden tube, also sometimes called the PTFE tube, has to be right against the nozzle inside of the hot end. If there’s any gap, the filament can sneak in it while it’s melted and create a clog. If this was the case, you’ll first have to clean the whole hot end then make sure you’re pushing the PTFE tube all the way against the nozzle during reassembly;
  • Upgrade or get a new hot end/nozzle
    If everything else has been tried but clogged nozzles are still a frequent issue of yours, your hot end or nozzle might have worn down too much or could simply be of bad quality. You should consider upgrading or buying a new hot end and nozzle.

If you still end up with a clogged nozzle, here’s what you can try to fix the issue:

  • Manually push the filament through the printer’s head
    Sometimes the clog might be very little but enough that the extruder wasn’t able to push the filament through it and it ended up grinding the filament on that specific part. By manually pushing the filament yourself, you can exert more force than the extruder and get rid of small clogging issues.
  • Unload and reload the filament
    If manually pushing the filament doesn’t fix it, you can try to do the whole unloading and reloading filament steps. Unloading the filament might be able to unload the clog at the same time. You can try heating up to a lower temperature when unloading so the filament isn’t fully melted and the clog is more likely to stick to the rest of the filament. Down to half of the normal printing temperature of the specific filament.
  • Clean the inside of the nozzle and hot end
    If the two previous methods weren’t enough to get rid of the clog. You’ll have to go through the much longer step of fully cleaning the inside of the hot end and nozzle. This is going to be very specific for each printer on how to do it so you should refer to your printer’s manual.

The filament is grinded

Picture by Lévi PONSARD

Grinded filament happens when the extruder can’t push the filament forward or backward. So instead of moving, the filament gets grinded up by the extruder’s gear. Let’s see why it can happen and how to avoid it:

  • Clogged nozzle
    As said in the previous issue, a clogged nozzle can easily create a grinded filament. As the filament can’t come out of the nozzle, the extruder won’t be able to push the filament forward and the gear will start to grind into the filament instead. This is the main reason grinded filament can happen and you should always make sure you don’t have a clogged nozzle as well.
  • Clean the extruder
    The extruder’s gear can get dirty with small bits of plastic. This can reduce how much the extruder grabs onto the filament and makes it more likely to grind on it instead of pushing it. You should check the extruder’s gear to make sure it’s not too dirty.
  • Reduce the flow of material
    If you’re trying to flow too much material in a nozzle too small for it, the filament won’t move as fast as the extruder is pushing it. You can reduce the flow and printing speed to allow the filament to get out of the nozzle.
  • Don’t use a layer height too small
    Printing too close to the previous layer or to the bed can block the filament from coming out freely out of the nozzle. If it’s blocked for too long, the filament will start to get grinded up.
  • Knot on the filament
    On the other side of the filament, you can also have a problem of it being stuck. If the filament had a knot, it’ll most likely completely block it from being pushed through the extruder. Knot on the spool can be caused by not carefully winding it back when unloading material, not properly blocking the end of filament or simply caused by the filament manufacturer.

If a grinded filament does happen to you and all the mentioned issues have then been fixed, you just need to push it past the grinded part or unload it and then cut the filament behind the grinded part.

A blob of plastic formed around the nozzle

Picture by Steven BEECROFT from makersteve.com

An extruder blob is probably one of the scariest sights coming back to your printer after a long print. Let’s see what can cause an extruder blob then how to get rid of it:

  • Print did not stick to the bed
    If your print moves from the bed, the printer will start to print without a previous layer to get stuck on. This will allow the filament to move freely. This usually creates what’s called a “spaghetti”. However, in some cases, the plastic can come back to the nozzle and get stuck on it. When the plastic starts to get stuck on the nozzle, it can start to build up a big mass and create the extruder blob.
  • Dirty nozzle
    If your nozzle is dirty before starting a print and already have some filament stuck to it. It’ll make it a lot more likely for the printed filament to get hooked onto it and start creating a blob. Always make sure the nozzle is clean at the start of a print.
  • Keep an eye on the printer
    If possible, you shouldn’t let the machine print unattended for a long period of time. Come by the machine every now and then to check for any issues. Since an extruder blob is a problem that builds over time, the earlier you can spot it, the easier it’ll be to clean afterwards.

Now let’s talk about how to remove an extruder blob in case it does happen to your printer. The first thing you’ll need to do is heating up your nozzle. You should go around 30°c higher than the normal printing setting of the material you’re using. When the printer reaches that temperature, you should still wait another 5 minutes for the plastic around the hot end to melt. At this point, smaller blobs will probably fall by themselves. You can grab onto the blob with pliers or heat resistant gloves and pull it out. Be very careful if the blob is close to any cable as you might damage the printer and even cause an electrical short. If the blob is very close to the cables, you can also turn off the printer after the hot end has heated up to avoid any short. When the blob has been removed, don’t forget to clean the hot end and nozzle really well.

Extruder or the other motors are making weird noise

Picture by Lévi PONSARD

A stepper motor starting to make clicking noises is a sign something is going wrongly. It’s a very noticeable sound compared to the normal turning of the stepper motor. That click indicates that the motor has skipped a step. This is due to the force required to make that step higher than the motor’s strength.

  • Extruder making clicking noise
    An extruder making clicking noise is due to not being able to push filament. As we’ve seen before this can have multiple causes such as clogged nozzle, printing too close to the bed, moist filament, etc
  • Other axis motors making clicking noise
    Check if there’s anything blocking the axis, the smooth rods and bearings. Clean and lubricate the smooth rods and lead-screws (Z-axis). Overheating can also be a cause of this, allowing your motor to fully cool down before doing more testing.

The nozzle is smoking

Picture by Lévi PONSARD

Your nozzle can either steam or smoke. This small difference will indicate where the issue is coming from and how to fix it.

  • If steam is coming out of your nozzle
    This indicates that the filament’s moisture is very high. While this is mostly harmless, your print’s quality will most likely suffer greatly. To dry up your filament, you can use food driers of appropriate size and make sure they’re stored in a dry container to keep a great longevity of your filaments.
  • If smoke is coming out of your nozzle
    This usually happens when the manufacturer has left some chemical on the nozzle. When heating it up, you’ll burn these and create smoke. If you see this happening, you should instantly turn off the power button of the printer and clean the nozzle. It can also be due to small bits of filaments left on the nozzle burning. As said plenty of times before, you should always make sure your nozzle is clean before starting any print.

Other printer issues

There can be many other issues that happen on your printer. These will, however, be very specific to each printer and the way to fix them too. You should use your printer’s manual or search online for any other issue you’re facing.

Maintenance

In this part you’ll learn how to go through the basic maintenance steps to keep your printer working smoothly for a long time.

On an FDM 3D printer, there’s a lot of moving parts as well as heated parts and melted plastic. This combination makes for a tool that’ll need to go through some basic maintenance steps. Avoiding these will result in lower quality prints or even failed prints. In the worst cases you could also end up breaking the print.

One of the parts that’ll be worn-down the most is the printing bed. As it’s directly in contact with the melted plastic as well as an adherence layer if needed. It’ll need to be cleaned regularly. This is one of the best ways to help with 1st layer adhesion. The printing bed can be made of many different materials, and as such, will need to be cleaned differently. We’ll go over the main ones.

Picture by Lévi PONSARD

Let’s start with glass beds. A very popular printing bed solution for the smooth finish on the first layer. However, since the glass bed usually doesn’t give too much adhesion, hair spray or glue stick is often used to get that adhesion. For that reason, glass beds will have to be cleaned regularly. The first tool you can use to clean your glass bed is a scrapper. You can also heat up the bed so residues are softer and easier to scrape off. You’ll need to apply a decent amount of force while scraping off, so make sure you’re wearing scratch resistant gloves or be very careful. When this is not enough, you can turn to soap and warm water. Those will allow you to scrub off the hair spray and glue very effectively. You can also use specialised cleaning solutions like window cleaner or IPA.

 

Picture by Lévi PONSARD

PEI sheets are another very popular printing bed. Their advantage is offering good adhesion without the use of an extra adhesive while still giving you a very smooth finish on the first layer. However, to keep that great adhesion, the PEI sheet will need to be cleaned very regularly and is also much easier to damage than a glass bed. The use of a scrapper here is discouraged as it can easily damage the PEI sheet. You should wait for the print to cooldown so it can detach easily. IPA, at a concentration of 70% or higher, should be used on the cold bed with a dry cloth. You can apply just a little bit of IPA and wipe it off between every print and you should be able to keep great adhesion and a long longevity of your PEI sheet.

Picture by Lévi PONSARD

Yet another very popular printing bed surface are flexible sheets, they come with the great advantage of being able to bend themselves to detach prints easily and without any tool. However, these can also come with different surface finishes, and as such, there’s no one single way to go about cleaning all flexible sheets. Make sure you know what kind of surface you’re working with and how to clean that specific one.

The other part getting dirty a lot will be the nozzle of the printer. Filament will often curl back and stick to the nozzle. As this can have several impacts on your prints, special attention should be given to keeping the nozzle clean. A good practice is whenever you’re starting a print job and the nozzle is heating up to the final temperature, you can observe if it’s dirty and clean it if needed. When the nozzle has reached a high enough temperature, like 150+ c°, you can use a wired brush to remove any filament stuck to the nozzle.

Picture by Lévi PONSARD
Picture by Lévi PONSARD

As well as getting dirty, the nozzle can also simply worn-out over time. Most are usually made of brass which is a pretty soft metal and won’t last forever. A worn-out nozzle can also create a lot of issues when printing. When buying new nozzles, make sure they’re compatible with your printer and more especially the hot end that’s installed if you’ve upgraded it. As said before, nozzles are usually made of brass but not only, you can find nozzles in different materials which will give you different qualities.

Picture by Lévi PONSARD

Changing your nozzle will require a few tools. You’ll need a channel lock or a crescent wrench to grip the heater block, another wrench to unscrew and screw the nozzle and a pair of heat resistant gloves to protect your hands as we’ll need to heat up the nozzle. The nozzle typically needs a 7 or 8mm wrench to grip onto them but not all nozzles are the same.

 
Picture by Lévi PONSARD

Before starting to unscrew the nozzle, we’ll first need to unload any material left on the printer and remove any shielding element that could block the access to the nozzle. You can now heat up the nozzle to 240c°. As the nozzle heats up and expands, the threading loosens up and it makes it much easier to unscrew the nozzle. Trying to unscrew the nozzle while cold can result in breaking the threading. 

Picture by Lévi PONSARD

Now that the nozzle is hot, you’ll be able to remove it. Hold onto the heated block with the channel lock or crescent wrench. Then use the other wrench to unscrew the worn-out nozzle.

Picture by Lévi PONSARD

You can now replace the nozzle with the new one. When screwing it back, be careful to not screw it in too strongly. The nozzle should be put in tightly but not with excessive force. Install back anything you had to remove to access the nozzle and that’s it, you should now be ready to print on your new nozzle. Make sure you take note of the diameter size of the nozzle for your slicer settings.

Another point of failure and wear is the constant moving of all the axes of the printer. You should make sure nothing is ever blocking or in the way of any of the axes. You can also clean and lubricate the rods and the z-screw. When choosing the right lubricant, you should look at how it interacts for “metal on metal” or “metal on plastic” contact. You should also be wary of how it affects smooth motion of those parts.

Here’s some lubricants you can use and which part of the printer to use it on:

  • PTFE lubricant
    PTFE has one of the lowest drag coefficients and can be used to lubricate threaded rods on all 3 axes.
  • Silicone lubricant
    Another popular choice, oil-based silicone lubricant can be used for the X and Y axis but is not suited for Z-screw.
  • White Lithium Grease Lubricant
    A well suited grease for the Z-axis as it’s great for metal on metal contact. Moisture and heat are also not a problem for this lubricant.

To apply the lubricant, make sure to first clean every part that needs lubrication. You can use rubbing alcohol for better cleaning results. Then apply the lubricant and spread it evenly on the surface. When it’s been applied, move the axis a few times on its full length, either manually or through the control panel. If you can still see some lubricant built up on the rods, that’s a sign you’ve put in an excessive amount. Clean the excess with a towel or cloth and try to move the axis again to see if you still have too much.

If each of the axes moves smoothly, you’re all done with the lubrication process. How often you’ll need to lubricate your printer will depend on the environment, as well as the usage of the 3D printer. A dusty environment with a very used 3D printer will require a lot more maintenance.  Squeaky sounds as the axis moves around are a really good indicator that the printer is in dire need of a new lubrication application. Otherwise, once every few months should be enough for a typical use

Summary

In this content unit you’ve learned what a 3D FDM printer is, what to use it for, how to operate it in a safe manner, how to post-process the pieces that come out of the machine, how to troubleshoot issues on the print, and how to maintain the printer.

In the first part, you’ve learned the basics of how a FDM printer works by extruding filament on a hot end and moving the printer’s head and the printing bed moving on 3 axes. You’ve also learned about the different types of FDM printers like delta and rectilinear printers. As well as the applications of FDM printing like prototyping, small productions, DIY projects or repair, etc.

In the second part, you’ve learned about the safety measures to follow when working with FDM printers. You know about the burn and cut danger as well as the unhealthy vapour. You also know to use a dry powder fire extinguisher in case of fire and have a first aid kit available nearby.

In the third part, you’ve learned what a slicer is. You’ve also learned how to take a 3D object and import it into the slicer software to prepare it to be printed. Resizing, positioning, selecting the right filament, nozzle size, changing layer height and many more other settings. You then learned how to slice your model and verify the printing process before renaming and exporting the printing file.

In the fourth part, you’ve learned how to prepare the printer by cleaning and levelling the bed, changing the filament, starting the print and supervising it as well as removing the print when it’s done.

In the fifth part, you’ve learned how to go from the printed piece to a finished piece. You’ve learned how to remove supports, assemble pieces, and smooth the surface.

In the sixth, you’ve learned how to spot printing errors and how to avoid or fix them as well as issues on the printer itself. In the sixth and last part, you’ve learned how to maintain a FDM printer by cleaning different types of bed. Cleaning and changing the nozzle. As well as lubricating the different moving parts of the printer.

Quizz