When you have a 3D model and are ready to print, you need a program that prepares your file for your 3D printer. A slicing program takes an STL or OBJ file and creates G-code, the code that instructs your 3D printer where to move the print head to, how fast to move it, and what path to follow. Cura is Ultimaker’s slicing software.
In Cura you will find all the settings on the side panel. They are divided into different sections for navigability. If you do not see all the setting categories, you can go to the Preferences:Settings menu and enable or disable a setting. You can click on each setting category below to see more information.
- Machine—Settings related to the specific printer. You can define the nozzle diameter in the Settings panel. If you have a nozzle with an inner diameter that’s different from one of the default sizes, you can enter the size of your custom nozzle here. This setting will then override the nozzle size that is chosen in the Print Job screen.
- Quality—Settings that define the (visual) quality of the print. The layer height - one of the most often changed settings - is the thickness of one printed layer (in mm). With a thinner layer height you will usually increase the quality of the print, leading to a smoother surface and more detail visible in the Z-direction (height) of the model. On the other hand, by using thicker layers you can decrease the print time substantially.
- Shell—Settings related to the outside of the print. Wall Thickness adjusts the thickness of outside walls (on the X/Y axis) of the model. This value divided by the wall line width defines the number of walls and is generally a multiple of the line width. For example: when using a wall line width 0.35 mm, it will be logical to set the wall thickness to 1.05 mm (3 * 0.35), which means that 3 walls will be printed.
In general a wall thickness of 2 or 3 times the line width is sufficient. A higher value will create a sturdier model and decreases the chance of leaks, while a lower value can significantly decrease the print time and filament costs.
- Infill—Settings related to the inside of the print. Infill density defines the amount of plastic used on the inside of the print. A higher infill density means that there’s more plastic on the inside of your print, leading to a stronger object. An infill density between 10% and 20% will be enough for most objects though.
Instead of filling in the infill density as a percentage, it’s also possible to set the line distance. This determines the distance between each infill line, which has the same effect as changing the fill density.
- Material—Settings related to Material. Retraction is one property that can be set. At the places in a print where the printer has to do a travel move between two printed parts and you don’t want it to leave plastic in between the use of retraction is important. This means that the filament is pulled back by the feeder, so that it doesn’t leak from the nozzle during the travel moves. By using retraction, “stringing” (thin threads of plastic in between the printed parts) is prevented, resulting in a much cleaner final model. You have to be careful with flexible materials or models that require a lot of retractions though, as that might lead to grinding of the filament.
- Speed—Speeds at which the print head moves while printing. The print speed defines at which speed (in mm/s) the print head moves while printing. Based on this setting, Cura will also calculate how fast the filament must be extruded. A higher print speed will lead to a shorter print time. But keep in mind that increasing the print speed means that you might have to increase the temperature as well, to ensure the plastic is properly melted.
Although you can choose one overall print speed for the complete print, it’s also possible to use different print speeds for specific parts of the print:
- Infill speed: The speed at which the infill material is printed. Since (visual) quality of the infill is not important, you could use a higher speed for the infill. But keep in mind that this might affect the strength of your print.
- Wall speed: The speed at which the walls are printed. You can also set the speed for the outer and inner wall separately. Printing the outer wall a bit slower usually results in a better surface finish.
- Top/bottom speed: The speed at which the top and bottom layers are printed. A lower speed increases the reliability of closure of the top layers, especially on large area prints.
- Support speed: The speed at which support structures are printed. The quality of the support is usually not that important, so a higher value can often be used here.
- Travel—How the print head behaves while traveling.
- Cooling—Settings that define how the plastic is cooled. You can enable or disable the print head fans during printing. The print head fans will make sure that the material is properly cooled before the next layer is placed on top of it. Especially on layers with a short layer time and layers with bridges/overhangs, cooling will increase the print quality.
- Support—Options for support structures. Some models have overhanging parts, which means that parts of the model float mid-air when you would print the model. In this case you must use a support structure under the model to prevent the plastic from falling down. This can be achieved by enabling support.
- Platform adhesion—Options for how your model relates to the build plate. Options include Brim, Raft, and Skirt.
- Special modes—Features that influence printing. These modes include print sequence, surface made, and spiralize outer contour.
- Experimental—Experimental new features.
If you forget what a setting does, hover over the setting name with your cursor and the tooltip will be displayed.
Now that you know what everything does, you need ways to get around: rotating, panning and zooming.
|Rotate||Right+click+drag or use your arrow keys||CTRL+click+drag or use your arrow keys|
|Zoom||Scroll wheel or + and - keys||Scroll wheel or + and - keys|
Cura has two modes: Simple and Advanced. While you can use the simple default settings when you first start printing, chances are that even as a novice, you will want to explore the more advanced settings available to you. It is in the Advanced Setup that you have the opportunity to adjust your layer height, line width and infill density.
If you find a configuration of settings that you’re happy with for a particular kind of model, consider naming and saving that profile. To save a profile:
- Click on Profile in the menu bar or in the settings panel and select Add profile.
- In the dialog box select Add. Cura has now automatically added a new profile, which is visible in the list of profiles as a customized version of the profile that was selected.
- Click on the rename button and give your profile a descriptive name.
How to master Cura
To help you get started with Cura's many options, we asked designer Michael Curry (a.k.a.Skimbal) to delve into a few of Cura's settings and to explain what they do, why you might want to use them and when to modify them. Michael looked at Shell, Print Speed, Cooling, Support Material, and Special Modes, to help you navigate the less obvious aspects of these settings, he designed a few models to help you think about the settings.
As with any new skill, it's important that you do some of the experimenting yourself. Read through the sections, but make sure to also do some printing.
The shell setting adjusts the thickness of outside walls (on the X/Y axis) of the model. You might want to modify the shell setting based on the material you are using. All plastics shrink as they cool. Filaments like PLA, shrink a small amount, but others, like Nylon and ABS, shrink more extensively. The Horizontal Expansion setting will allow you to adjust the size of your 3D print in the X/Y dimension to compensate for the change in size that happens when the plastic shrinks as it cools. The ability to control the horizontal expansion is important when you're working with precise sizes.
Enabling Horizontal Expansion
A positive Horizontal Expansion value will add to the dimensions of your model. You should use a positive value when your printed model is smaller than you expected.
A negative Horizontal Expansion value will reduce the dimensions of your model. Use a negative value when your printed model is larger than expected.
Try it yourself
Each side in the X/Y plane should be exactly 20mm after printing. Take a pair of calipers and measure the dimensions. If your print is not exactly 20mm x 20mm, use the Horizontal Expansion setting to add or subtract the difference between the target value and what you have. Slice and reprint. What happens?
Z Seam Alignment
Enabling Z Seam Alignment
To enable Z Seam Alignment, Click the Gear Icon on the Shell Menu and enable the Z Seam Alignment check box. When the options menu closes, the Z Seam Alignment drop down will be added to the Shell Menu.
There are three options available for Z Seam Alignment: Shortest, Back, and Random. Shortest is Cura’s default value, and if selected, Cura will start each layer at the endpoint of the previous layer. While this is Cura’s default of setting, it comes the highest probability of creating a the visible seam. Selecting Back will start each layer on the back of the model, as it is positioned on the build plate. In Back mode you can change the location of the seam by rotating the model on the build plate. Setting Z Seam Alignment to Random will start each layer at a random position. Random mode will eliminate a seam, but will also lengthen the print time as the print head will require additional time to move to a new position between each layer.
Try it yourself
Download and print this:
Is there a visible Z Seam? Use the Z Seam Alignment setting to change the mode to Random and reprint the goblet. What happens?
Fill gaps between walls
Occasionally when you print thin walls, the areas between the inside and the outside of the wall is left unfilled. This might happen when the width of your wall is between a multiple of Cura’s line width. Cura leaves the inside and outside walls unfilled to prevent putting too much plastic into that section of the part, but it also means that gaps can show up in the print. Enabling Fill Gaps Between Walls gives you control over how you want Cura to handle these small spaces.
Enabling Fill Gaps Between Walls
To enable Fill Gaps Between Walls, Click the Gear Icon on the Shell Menu and enable the Fill Gaps Between Walls check box. A Fill Gaps Between Walls drop down will be added to the Shell Menu.
There are three options available in Fill Gaps Between Walls: Nowhere, Skin, and Everywhere. When Nowhere is selected, Cura will not fill any gaps. After enabling Skin, Cura will fill gaps that occur only on top or bottom layers. The Skin option is a balance between filling gaps and risking over extrusion. When you select Everywhere, Cura will fill every gap in your print’s walls, and will make your model’s outer shell as strong as possible.
Try it yourself
Notice the gaps between the walls. Use the Fill Gaps Between Walls property to set the mode to Everywhere, slice and reprint. What changes do you notice?
Alternate Extra Wall
The Alternate Extra Wall setting adds strength to the outer walls of the print without taking the time required to add additional shells on every layer of the print. Alternate Extra Wall will add one extra interior shell to every other layer. For example, if your print is set for two shell widths Alternate Extra Wall will add an extra one on every odd numbered layer.
Enabling Alternate Extra Wall
Try it yourself
Put it under the corner of a chair and crush it.
Number of Slow Layers will slow down the printing of the bottom layers and defines the number of layers it will take the printer to reach the set print speed. The speed, based on the initial layer speed and print speed, will linearly incline over the number of layers specified in the Number of Slow Layers setting. A higher value will decrease the chance of your print warping, but this setting can also increase your print time significantly.
The Print Speed setting is a basic parameter of Cura that affects how quickly your print head moves and it influences the configuration of many of the internal settings.
Print Speed settings
You will find Cura’s print speed settings in the Speed Menu. The four default values displayed in this menu are Print Speed, Infill Speed, Top/Bottom Speed, and Travel Speed. All settings are in millimeters per second (mm/s).
- Print Speed—The overall maximum speed for the print. It determines how quickly the print head will move while adding plastic to the model, and is used in many of the calculations Cura preforms.
- Infill Speed—the speed the model’s infill is printed at. By default it is the same as Print Speed.
- Top/Bottom Speed—The speed at which the models top and bottom layers are printed. By default this is set to one half of the Print Speed.
- Travel Speed—The speed the print head moves when it is not extruding plastic. The default value for this property is 120mm/s.
The faster the print head moves, the sooner your model will be finished printing. But models printed too fast can start to lose quality. They may show ripples on their surface from vibrations in the extruder or become brittle from too little heat applied to the plastic. However, with some experimentation and tweaking you can make adjustments that shorten print times and still produce great results.
How to make changes
The simplest options is to increase the Print Speed value. Raising the Print Speed will automatically increase the Infill and Top/Bottom speeds, and the whole print will run faster.
Unfortunately just increasing the print speed may adversely affect your model’s finished outer surface. Waves and lines may start to appear, and small details might become obscured. To maintain your print quality, keep the print speed set to its default, and instead modify the Infill Speed. Raising the Infill Speed will make the print head run faster when printing infill, but run at normal speed while printing the model’s top, bottom, and sides.
Try it yourself
Print it at Cura’s default print speed. Now increase the Print Speed by 10mm/s and print it again. What changes? Increase the print speed by another 10mm/s and see what happens.
For more information about printing faster see the Ultimaker Education Print Faster resource.
There are certain situations that call for printing slower than the default print speed. Models with fine details and very small profiles will come out better when printed slowly. Some materials, like PET+ or Flex PLA, also require slower print speeds to work properly.
How to make changes
To slow down the print speed, the simplest option is to lower the value of Print Speed setting. Changing this setting automatically adjusts the Infill and Top/Bottom Speeds. Filament manufacturers will often have a “suggested print speed” for their specialty filaments. For highly detailed models, start by lowering the print speed by 10mm/s, then adjust it up or down in increments of 5mm/s as needed.
Try it yourself
Print it at Cura’s default print speed. Now decrease the print speed by 30mm/s and print it again. What changes? What will happen if you lower the print speed more?
When filament is extruded it remains malleable until it cools. Most 3D printers use cooling fans to speed up this process and harden the material extruded almost as quickly as it is laid down.
An Ultimaker 2+ has two cooling fans, one on each side of its extruder. These fans blow air through metal ducts down onto the most recently printed section of the model. The cool air removes heat from the deposited plastic, and hardens it into the correct shape. A proper cooling system also prevents previous finished layers from being distorted by the heat of the next layer being applied on top of them.
Why do you cool
Cooling improves the surface quality of all prints and helps your printer accurately produce small details and special structures like bridges or overhangs. A 3D printer without a cooling fan relies on the cooling effect of the ambient air, and must run more slowly in order to achieve the same quality results.
When to use cooling
By default Cura enables the cooling fans for all prints, and for most projects, you should should leave the fans enabled. You might notice that when you print with PLA the fans are not enabled during the first layer. This is normal. Cooling the bottom layer would reduce the print's ability to adhere to the platform. If you are printing in other materials and you notice that your part is breaking or splitting on layers, you probably have too much cooling. Many materials need only a small amount of cooling, around 30%. When you start to use different nozzles or alternative filaments like Nylon, disabling the fans will become a necessity.
Here are three situations where you may need to adjust your cooling setting:
- Your filament requires cooling to be disabled. PET+ and Nylon are two examples of filaments that cannot be printed with cooling fans enabled.
- Your fans are cooling the nozzle too much and the 3D printer cannot keep the extruder at the proper temperature.
- Your cooling fans cannot sufficiently cool the part, and it is still being distorted by the heat.
Your filament requires the cooling fans to be disabled
Some materials like PET+, Polycarbonate and Nylon need to be printed in still air. These materials shrink as they cool and the temperature difference caused by the fans will warp and distort the object during printing.
Disabling cooling in Cura is easy. Click the Cooling Menu and it will drop down to reveal an Enable Cooling Fans checkbox. Uncheck the box and Cura will disable the cooling fans in the G-code.
Too much cooling
Cooling is a balancing act between the extruder needing to stay at its set temperature, and the printer’s need to rapidly cool the part. If you are using a nozzle larger than 0.4mm, or a nozzle with a hole 0.8mm or larger, you may find your printer cannot keep the extruder at its desired temperature. This happens when the combination of plastic moving through the nozzle, and air blowing against it remove heat faster than it can be replaced. In most cases, if this combination of factors goes on for more than a few minutes, the printer will enter a safety mode and display “Error - Stopped, Heater Error.”
The cooling fans can be slowed to reduce the amount of cold air they blow against the nozzle. Click the Gear Icon on the Cooling Menu and enable the Fan Speed checkbox. The Fan Speed setting will be added to the Cooling Menu. The value is set as the percentage of the fan's’ maximum speed. If you need to adjust the setting, start by modifying the value to 80%. Be aware that for values below 20%, the fans may not receive enough power to spin at all.
The cooling fans are running, but parts are still being warped and melted by the heat of the nozzle
For very small prints sometimes a layer can print so quickly the cooling fans don’t get a chance to fully cool the material in place before the beginning the next layer. This situation leads to an ugly mess.
You can give the fans more time to cool the layer by slowing down the print speed on these small layers. Click the Gear Icon on the Cooling Menu and enable the Minimum Layer Time check box. A Minimum Layer Time setting will be added to the Cooling Menu. This value sets the minimum time a layer will take in seconds. The default value is 5 seconds. A good rule of thumb is, if you need to adjust the Minimum Layer Time start by increasing it to 10 seconds, then continue to make adjustments in 5 second increments as needed. Cura will adjust the G-code to slow the printer down when necessary so that no layer will take less than the Minimum Layer Time value.
Expert tip: When printing a series of small parts, print them all together. The travel time between the parts is often enough time for the layers to cool without changing your settings.
Try it yourself
To make it print properly, you’ll need to tune the Cooling settings in Cura.
What changes to the cooling setting would you have to make to 3D print the Amphora in Nylon?
Support material is additional structure generated by Cura to provide support to the model which wouldn’t have any stability otherwise. Support parameters can be adjusted in Cura, and tuned for your model so that you can get the best 3D printed part with the easiest to remove support structure possible.
When to use support material
If you see red on the bottom of the part, where the model touches the build plate, you don’t have to worry about this area being unsupported. The build plate will take care of this problem. Small Red areas at the tops of holes or between two structures are called bridges, and Cura will handle them automatically.
The model in the image above has large free floating overhangs, and you would need to enable support by checking the Enable Supports box inside the Supports menu.
Basic support material settings
When Support is enabled there are two basic settings that appear: Placement and Enable Support Roof.
Everywhere is the default support mode and is the most commonly used. It creates support structures below all overhanging parts of the model. Supports will be created between the build plate and the model, and from one part of the model to another.
Selecting Touching Build Plate will create support structures underneath overhanging sections of the model only between the build plate and the model. This is useful for keeping complex models from being completely encased in support material, but it may not provide support to all overhangs.
Enable Support Roof
Adjusting support material
Cura’s default support settings are great for most applications, but sometimes it’s necessary to tune them for better results. You’ll need to make adjustments when you move between different materials. For example, Support settings that work perfectly for PLA will be different for 3D printing with Nylon.
The X/Y Distance is the distance between the support structure and the wall of the model in the X-Y plane. The larger the the value for the X/Y Distance setting, the larger the space left between the support structure and any unsupported wall it is parallel to. A larger distance will lower the chance that the support structure will leave marks on the model’s vertical walls.
To change the X/Y Distance, Click the Gear Icon on the Support Menu and enable the X/Y Distance check box. A X/Y Distance value will be added to the Support Menu. X/Y Distance value is in millimeters, and by default is set to 0.7mm. If your model has small features that are not being supported properly, you can reduce the X/Y Distance slightly. If you are having problems with your support material sticking to the sides of your model, increase this value in increments of 0.2mm until the sides of your model are smooth.
Z Distance is the space left between the top or bottom of the support structure and the surface of the model. The connection between the support material needs to be made weaker then the connection between the layers of the model. This way, when you pull on the support material it will break away without pulling the model’s layers apart. Cura creates this weaker connection by leaving a space between the top and bottom of the support structure and the model.
To change the Z Distance, Click the Gear Icon on the Support Menu and enable the Z Distance check box. A Z Distance value will be added to the Support Menu. This value is in millimeters, and by default is set to the layer height. So if your layer height is 0.15mm the default Z Distance will be 0.15mm. If your support material is difficult to break away from your model, increase this value in increments of your layer height until it comes away cleanly. Cura can either add support on any given layer or not add support. Unfortunately there are no "half layers of support." So if a 0.3mm Z Distance setting for a print with a layer height of 0.15mm is too much, and the Z Distance of 0.15mm is not enough, you're out of Z Distance options.
Cura generates support material in one of five patterns. In most cases the default pattern, Zig Zag, will generate the best balance between strength and ease of removal. The other pattern options are Triangles, Lines, Grid, and Concentric. They are all available for you to experiment with.
To change the Support Pattern, Click the Gear Icon on the Support Menu and enable the Support Pattern check box. A Support Pattern drop down box will be added to the Support Menu.
Try it yourself
Print them using Cura’s default support settings. Now adjust the the Z Distance so it is 0.17mm and print the model again. What changes? Reset the Z Distance and adjust the X/Y Distanceto 0.9mm and print again. What changes?
Also experiment with the X/Y and Z Distances with these models:
Spiralize Outer Contour
During a spiralize print the Z-Axis moves down at a continuous rate, as opposed to the more typical step down at the end of each layer. There is no start or stop point on each layer and the whole model is printed as one continuous spiral of fused plastic. In an ideal Spiralized print the extruder never stop extruding plastic. When Spiralize is enabled, you will hear continuous clicking from the Z-motor when printing as the bed is moving continuously rather than once per layer.
There are limitations to using Spiralize. Models cannot have overhangs exceeding 45 degrees, or the walls will start to distort and collapse, and flat areas parallel to the build platform cannot be printed. Because your spiralized model is built with one wall thickness, your printed part is fragile and will break if handled roughly.
To enable the Spiralize Outer Contour, Click the Gear Icon on the Special Modes Menu and enable the Spiralize Outer Contour check box. A Spiralize Outer Contour check box will be added to the Special Modes Menu. When Spiralize mode is selected, Cura will still respect the layer height, print speed, and other basic settings in Cura. This means that you will need to select the Layer Height and Line Width. Set Wall Thickness to the same value as your Line Width, change Wall Line Count to 1, set Top Layers to 0 and set the infill density to 0%.
Spiralize prints are only one nozzle width thick. To increase the stability of the print, consider enabling Brim from the Platform Adhesion menu. The Brim setting will add a base around the model to help the model adhere to the platform as it is printed. Another strategy is to over-extrude. If you want a watertight cup or vase, set your nozzle to be larger than it actually is. Or set the flow rate on the printer to 140%. If you do adjust the flow rate, you need to print twice as slow as you normally would.
Switch to Layer Mode to preview the G-code before sending it to you printer.
Try it yourself
Select one of these models, download and print using the Spiralize:
Surface Mode is an unusual tool that prepares files to print by following the outer surface of the 3D model instead of its enclosed volume. In this mode non-manifold models and orphaned geometry with no thickness can be printed as walls a single nozzle width thick.
The Surface Mode setting has three modes that control how it works, Normal, Surface, and Both. Normal functions much like the usual cura slicer, attempting to make solid shapes from any orphaned geometry. Surface prints all faces in the model as single nozzle width walls with no infill. Both runs both tools together. The walls will be printed, and Cura will try to fill the space between them with plastic.
Enabling Surface Mode
To enable the Surface Mode, Click the Gear Icon on the Special Modes Menu and enable the Surface Mode check box. A Surface Mode drop down menu will be added to the Special Modes Menu.
Try it yourself
It has orphaned walls that aren’t connected to a solid volume. Experiment with the Surface Mode settings to see how each mode affects what is printed.
Post processing plugins
In addition to the settings in the right panel, Cura also comes with a few post processing plugins. These options can be found in the file menu at the top. Select Extensions: Post processing:Modify g-code. Add a plugin as follows:
- Select one of the available scripts on the left most window by clicking the ‘+’ button.
- The selected script will be loaded into the The active scripts middle column window.
- You can change the order of the plugins with the arrow buttons or remove the plugin with the ‘x’ button. The last column displays the details and values.
The Pause at Height plugin will pause the print at the height specified by the value entered in the third column. When the print is paused, you can change the filament or add fabric (see Digital fabric).
Try it yourself
More experimentation: using different settings in one print
Cura has a feature called Per Object Setting that allows you to apply different settings to different parts on the build platform. If you want to have different slicing settings within the same part, you can take a few additional steps and then take advantage of the Per Object Setting.
- Find a model to work with. Make sure that there is enough model to work with if you divide it into sections.Cat (standing up)by Scintilla
- Netfabb Basic is a free program that can often help you fix problematic models, such as reversed normals, bad edges, and holes in the mesh. It also allows you to divide a model into separate parts.
If you do not already have the program, download and install Netfabb Basic.
- Open your model in Netfabb:
- Use the cutting tools to divide your model into sections:
- Change the view to make another cut:
- CTRL+click on each section and export them, keeping track of what parts. You can use part1, part2, part3 or right_front_top, right_front_bottom. Use whatever convention that helps you keep track of your parts:
- Import your parts into Cura:
- CTRL+ click on a part and then select Per Object Setting:
- For each part, set your values. Using Per Object Setting lets you assign different values to each part:
- When you have assigned values to each part, select all the parts (on a Mac, use Command-click):
- In the top menu, select Edit:Merge Objects. Cura will put your object back together while preserving the Cura settings for each part:
- Export the G-code and print:
For more information about Cura see Cura 2.12 has been released.