How to optimize UltiMaker Cura support settings

UltiMakar Cura offers a powerful range of settings to enhance your 3D prints. Learn about Cura's basic maintenance settings and how to best maintain your prints.

All fused deposition modeling (FDM) 3D printers create objects by extruding layer after layer of thermoplastic material. Therefore, each layer must be restrained by the layer below it. When there is no layer below it (as is the case with overhangs and bridges), the model may simply need support structures. They are printed with the base model and separated during post-processing.

"That doesn't sound too terrible," you might think. However, the word "maintenance" terrifies many manufacturers. After all, support structures not only require more material, but are also known to have a negative impact on the print surface and to be difficult to remove.

Unfortunately, with 3D printing, it is a fact that some models just need supports. But that doesn't mean we can't optimize them by adjusting the appropriate settings.

In this article, we'll first talk about when you do and don't need maintenance. Next, we'll dive into some important Cura support settings to tweak for best results. Although we're focusing on Cura, the basic principles behind the settings can be applied to a variety of other slicers. So let's get busy!

Do you need props?

There are a few things to consider in determining whether or not you need support structures:

• 45° rule (overhangs): If the overhangs are greater than 45° (with respect to the vertical), they will need support. To test your printer's overhang capabilities, try printing an overhang test. 
• 5mm rule (bridges): If the bridges are wider than 5 mm, they may need support. Of course, not all 3D printers are the same. Some can print longer distances, while others can barely print any range. Try printing a bridge test to determine when your printer needs maintenance. You'll know the threshold once you find the distance your printer's bridges drop.

Next, let's dive into the settings to refine the supports in case you've decided you need them.

Settings

UltiMaker Cura has several settings to help you optimize the supports of your models. Here's how to get started:

1. When you first open Cura, click Settings. Here you can adjust settings that are otherwise hidden under "Recommended" settings.
2. Left-click on the menu (three lines to the right of the search bar) and select “Configure Setting Visibility…”
3. Select "All" from the drop-down menu.

Now you can see all the settings that UltiMaker provides in Cura. Scroll down to Support Settings, click "Generate Support" and let's get started!

Extruder for overhang

With the rise of dual-extruder 3D printers comes the ability to print core parts from one material and use the other extruder to print soluble (often PVA) supports. After printing, simply soak your part in the appropriate solution and forget about the extremely tedious removal of support material previously required.

In Cura, you can choose which extruder you want to print which section of your support structures, so you can print with a combination of PVA (or other soluble material) and filament of your choice.

You can define the extruder for the following support sections:

• Support infill
• First layer support
• Support interface
• Support roof
• Support floor

To begin with, let's look at the basic settings regarding the structural aspects of the supports.

Tree

Tree type support is an alternative to the typical straight and vertical version. To enable tree supports, select "Tree" from the "Support Structure" drop-down menu.

As the name suggests, a tree support is hollow that supports models with "branches" that curve with different angles, sizes, and paths that can be defined by certain parameters in Cura.

The default settings are pretty reliable, but here are all the settings that can be adjusted:

• Tree Support Branch Angle: Maximum branch separation angle.
• Tree Support Branch Distance: Distance between the support points of the branches. This is the density of the tree support.
• Tree Support Branch Diameter: Diameter of the thinnest branches in the support.
• Tree Support Trunk Diameter: Diameter of the thickest branches in the support.
• Tree Support Branch Diameter Angle: Increasing the angle increases the diameter of the bottom of the branches.
• Tree Support Collision Resolution: Resolution used to calculate whether your model and a tree support will collide.

These settings are pretty straightforward, just keep in mind the trade-off between wood strength and removeability.

Model

Cura offers a variety of support structure models. Each exhibits a balance between strength and ease of removal, and some are better suited to certain shapes. Here is a list of the most used models:

FAST AND EASY

• Zig Zag  is the fastest to print and the easiest to remove.
• Lines are the next step. It still makes great, easy-to-remove supports, but it's a bit sturdier than zigzag.
• Concentric is best suited for models with shapes similar to spheres or cylinders. It tends to be a bit stronger than zigzags and lines.

Note that due to the one-way nature of the above three patterns, they tend to be more vulnerable. Vibration and weak support structures, for example, can cause a layer to not line up perfectly with previous layers, which can cause problems in the long run.

Also, if these models are caught even slightly by a moving nozzle, they can detach from the surface below and collapse.

STRONG

Both Grids and Triangles are great patterns for achieving strong supports. They are more resistant to vibrations; however, they increase print time and generally show more contact with the support areas. This can lead to more difficult post-processing.

Density

Backing density is similar to filling density in that you are making a trade-off between strength, speed and ease of removal.

High-density load-bearing structures are generally stiffer and can withstand vibration. In addition, the increased contact with the overhangs makes high-density supports ideal for complex or detailed support areas. With high-density supports, expect more reliable support, but also higher filament usage, longer print times, and more difficult post-processing.

Low density supports are ideal for normal support areas that do not require many contact points. They are more prone to vibration during printing, but reduce filament costs, print time and the difficulty of backing removal.

20% support density is a great place to start, but adjust this value according to your model's needs.

Thickness of the filling layer

To reduce support printing time, you can print support fill layers at a lower resolution. The support doesn't have to look pretty, it just has to support your main model. If you decide to print with large support layer heights, be sure to make the thickness of the support layer to fill an exact multiple of the resolution of your model. Otherwise, Cura will round it up to the next multiple, which may be more than intended.

Incremental maintenance steps

This setting determines how many times Cura will reduce the fill density of the support the further away it is from the support overlay. This setting can help you save support materials and print time by only using a high support density when in contact with or near the model you want to support.

You can also specify the step height for the gradual fill to set how close the density steps are.

Towers

Finally, for very small overhangs, Cura allows you to print supports like towers that taper at the top to support areas smaller than your specified minimum diameter. (Other support areas will use normal support structures.)

To keep these support towers from being too weak, they have a larger diameter than the area they support. You can always change this diameter in Cura. You can also adjust the angle at which your turrets rise to a point, making the turrets flatter or angled.

Placement

Once you've decided on the type of support structure you want, the next setting is Support Placement. Here you can choose “Everywhere” or “Touching Buildplate”. As you can probably guess, this determines whether the supports are printed everywhere (where needed) or only originate from the build plate.

In most cases, a Touching Buildplate is best because building a support all over the place can cause some nasty imperfections on the surface of your print.

Sometimes, though, you just need supports everywhere. This is the case with particularly complex models that would be impossible to print without supporting structures.

Overhang Angle

With this setting you can specify the angle of the overhang beyond which you want to generate supports. As mentioned earlier, the default angle is usually 45°. However, this may be different for your particular machine. Play around with an overhang test to determine how well your machine handles different angles.

The angle of the support overhang may also differ for each seal. If you want to support bridges only in a specific model, you can choose 90°. If you want support for each overhang, select 0°.

Minimum support area

This setting simply determines the minimum area to maintain by filtering out the places where you don't want maintenance. This setting can save you unnecessary material consumption and printing time.

The following are additional features or materials that have been added or created for the supporting structures.

Support Brim

Just like model brims, Support brims are concentric lines of material printed on the inside of your support structures to improve the adhesion of the build plate to your initial layer. Enabling them in Cura will improve the reliability of the support structures by making sure that the supports don't pop off the build plate or tip over.

Support brims are ideal if you have traction issues or use support structures with a small base. Therefore, increase the support edge settings for a firmer grip on the plate.

Join Distance

Support Join Distance adjusts the maximum horizontal distance between support structures. When two supporting structures are closer to each other than this value, they will be printed as one structure. The higher the value for this distance, the faster the supports will merge. If the support structures are particularly thin, a larger joint distance can help provide a stronger support for the model.

However, if you set this value too high, the support structures may become dense and difficult to remove.

Support Interface

If you need a smoother connection between your model and supporting structures, you can enable the support interface. This is a solid skin on the roof and floor of your prop that provides a solid contact surface with the model. When enabled, the support interface makes unsupport more difficult, so be aware of the trade-off.

With this setting, within Cura, you can adjust the supported interface thickness, resolution, density, pattern, area, horizontal extension, and line directions.

Last, but certainly not least, the following settings are related to the overall size of the supporting structures (and can mean increasing or decreasing them, for example).

Z distance

This important setting determines the distance from the model to the top and bottom of the support. This setting has two sections: Top Spacing and Bottom Spacing.

A high value for these distances creates a larger gap between the model and the support, which means easier post-processing. Creates a smoother model surface due to the reduced number of contact points. A low value is useful when trying to maintain complex overhangs that require high detail. But the low value makes the supports harder to remove.

As always, play around with some distances to find the ideal value for your printer. Just make sure your Z distance is a multiple of your layer's height so your printer can accurately achieve that distance.

X/Y distance

The X/Y distance is similar to the Z distance. Adjusts the horizontal distance between the model and its support. Again, the greater the distance, the easier the process of removing the support. The smaller the distance, the stronger the support structure.

Generally, a larger X/Y distance will mean better surface coverage of the vertical sections. If the vertical parts in your prints are roughened by adjacent supports, try increasing the X/Y distance.

A lower X/Y distance will result in better support for overhangs, namely those next to vertical surfaces. However, they can cause surface imperfections on vertical surfaces and can make post-processing difficult.

Distance Priority

Depending on the type of overhang you are trying to print, the Z distance may conflict with the X/Y distance. In Cura, however, you can prioritize these distances so that in the event of a conflict, the most important distance is maintained.

It's usually best to have Z replace X/Y because the Z distance is what really holds the model. However, you can change this override setting if a particular model requires it.

You can also set a minimum X/Y distance. Then, even when the Z distance takes priority, the minimum X/Y distance is still maintained.

Stair Step Height

If you have chosen "Anywhere" to place a support, the height of the staircase is an important parameter to consider. This setting determines how closely the support material follows the contours of your model. The lower the stair height, the closer and smoother the connection, making the support interface surfaces smoother. The higher the height of the staircase, the rougher the connection, which makes removing the support easy.

Horizontal Expansion

When the areas requiring support are very thin, it is difficult for your printer to create strong structures to support such a small area. This setting allows you to set a horizontal extension so that even small support areas are adequately supported.

Entering a large value for this setting will always result in stronger supports, but this setting requires more thread.