Cura Ironing Explained
Ultimaker Cura is a free, open-source 3D slicer that converts 3D models into 3D printable G-code. It contains a plethora of adjustable settings and features that allow you to control how your part is printed and tune certain aspects of your print. As the slicer has grown in popularity over the years, more features – like fuzzy skin and print one at a time – have been included based on the interests of users.
Ironing is another one of these innovative slicer features. It can achieve super smooth top layers on 3D prints, which is especially useful for printing visually appealing models – like cosplay parts, signs with text, and art pieces – where top surface quality matters. Ironing can also make the painting of parts easier because the paint will better stick to the surface.
Although ironing is still considered new and experimental, it actually dates back to 2016. A user named Neotko on Ultimaker’s community forum proposed the idea and created a prototype ironing feature, known as Neosanding, in Simplify3D. After gaining some popularity in the 3D printing community, Cura’s developers added ironing to its portfolio of features in version 2.7 of Cura and, since then, they’ve continued to add new ironing features that give users even more control over the process.
In this article, we’ll go over how you can use ironing in Cura. Before diving into Cura’s ironing settings and how you can use them, we’ll first review how ironing works.
How Does It Work?
Like ironing clothes, ironing for 3D printing involves using heat to smooth out a surface. This is achieved on a 3D printer by moving the nozzle back and forth over the top layer. This melts any material sticking up and forces it back into the top of the print by pushing the nozzle over it.
On top of brushing the heated nozzle over the layer, ironing also involves extruding a small amount of material. This extra extrusion helps fill any gaps on the top layer, making the surface even smoother. To prevent blobs or other blemishes resulting from over-extrusion, only a small fraction of the regular extrusion quantity is used during ironing.
While ironing is great for printing signs and parts where appearance matters, it’s not without its downsides. First, as the nozzle has to make another pass over the top layer, ironing increases the print time, especially when there’s a large surface area on the top layer.
Second, ironing can only be performed on parts with flat top surfaces, as the nozzle can move back and forth easily on these types of models. You shouldn’t use ironing on objects with curved features at the top (e.g. spheres) because ironing won’t be effective.
Third, if the settings aren’t properly tuned in your slicer, ironing can lead to poor visual quality on models, sometimes even worse than if ironing had never been activated. That’s because the ironing process requires a high level of precision in its settings to achieve a smooth top layer.
Lastly, in addition to its own settings, ironing is sensitive to other related printing issues like extrusion, speed, and temperature. For this reason, it’s crucial that you tune and calibrate your printer before ever activating ironing, or else you may run into more problems.
Now that you know how ironing works, let’s get into how to enable ironing in Cura and tune its settings.
As we’ve discussed, ironing is a helpful feature for printing parts that require a smooth surface, but it isn’t necessary or ideal for all prints. For example, using the feature on models with curved or pointy top surfaces will create “stair-stepping” on the surface. For these reasons, we suggest using ironing on a model-to-model basis, especially when you believe the benefits outweigh the downsides.
You can follow the steps below to activate the ironing feature in Cura and unlock the corresponding settings:
- Open Cura.
- Click the three-bar menu icon from the Settings menu. Check that “All” is selected for your visible settings options.
- In the Settings box, scroll down to the “Top/Bottom” section.
- Find the “Enable Ironing” setting, and click the check-box to activate the feature.
Once activated, Cura will reveal a few ironing-specific settings immediately below the “Enable Ironing” option. Each one of these settings controls a different element of how ironing is performed. Below, we’ve made a list of the different settings and an explanation of what they do and how you can use them:
- Iron Only Highest Layer tells your printer to only activate ironing on the uppermost top layer and not any other top surfaces. For example, if you were printing a set of stairs, only the top stair would be ironed.
- Ironing Pattern controls the pattern that the nozzle follows when ironing the top layer. While theoretically, you shouldn’t see the pattern, you most likely will, at least to some degree. For this setting, there are only two options: “Zig Zag” and “Concentric”.
- Ironing Line Spacing controls the distance between each nozzle pass during ironing. The nozzle usually has a slight separation between its path lines because one ironing pass (line) can cover up and smooth more than one normal printing pass. Increasing this distance will also decrease print time but might also make the surface less smooth.
- Ironing Flow defines how much filament is extruded during ironing as a percentage of the printer’s normal extrusion. If set too high, you’ll notice over-extrusion on the top surface, while too low may not fill in all gaps. Also, if you notice scarring on the top layer of your prints (also a common issue with ironing), slightly reducing your ironing flow can help.
- Ironing Inset controls the distance between the edge of the top surface and where the nozzle begins to iron. If you set this value to 0, the entire top layer will be ironed. This can cause jagged edges, however, so it’s recommended to keep a little space.
- Ironing Speed controls how fast the nozzle moves while ironing a top layer. Typically, the slower the speed, the better the outcome. This will obviously increase print time.