Design freedom is one of the main benefits that 3D printing offers. The technology allows users to create parts with complex structures and internal infill geometries. But there are some limitations to what 3D printing can do. For instance, fused deposition modeling (FDM) 3D printers struggle to print geometries with bridges or overhangs that exceed angles of 45 degrees. But that doesn’t mean people have to avoid printing parts with such features. 3D printed support structures enable complex shapes with overhangs and fine details to be printed without trouble.
Supports are typically generated in slicing software and are applied automatically to areas of your 3D model that require the extra help. In addition to holding certain types of geometries up, supports can also help improve bed adhesion, reducing the risk of warping.
Printed parts with support structures do require some extra post processing. Specifically, it is important to remove the support structures carefully—either manually or using a solvent—to ensure that your 3D print is structurally sound and visually flawless. In this article, we’ll discuss the different types of support structures available for FDM 3D printing and explain the various methods for removing them without damaging your 3D print.
Types of support structures
When it comes to FDM, there are two main types of 3D printing support structures: linear supports and tree supports.
Linear supports, also known as accordion supports or lattice supports, are the most popular style of support structure. Linear supports are characterized by straight vertical columns that grow upwards from the build platform to support overhangs and bridges. This style is popular because it is highly effective at supporting these features.
In Cura slicer software, linear supports are called “normal” and users have the option to choose from various support patterns, including grid, triangle, concentric, and line. You can also choose the support density and whether to print supports with a wall—though this is typically only recommended when printing with a soluble support material.
While linear supports are the gold standard for supporting overhang features in 3D printed models, they do have a slight downside. Because they support so much of the overhang, they can be tricky to remove, increasing the risk of damaging or marking the final part.
Tree supports, or tree-like supports, are characterized by more organic structures that grow up from the build plate. Named for their similarity to tree branches, tree supports are most effective when printing angled overhangs. Because they have fewer contact points with the supported print, they are not very effective for holding up bridges or flat overhangs. That being said, tree supports are easier to remove than linear supports, since there are fewer touch points.
Tree supports are usually hollow, which reduces the amount of material required to print them. Like linear supports, slicer software will automatically generate the structures, so you don’t have to. Users can, however, choose to adjust a number of settings for tree supports, including branch distance (i.e. how far apart the touchpoints are on the 3D printed model), branch diameter, and diameter angle.
Recommended reading: Tree supports: Better looking prints with less wasted material
Removing support structures
Once you have your supports and model 3D printed, the next step is to remove the supportive structures. The support removal method depends entirely on the type of material you have used for the supports.
Breakaway support structures
If you have a single-extruder 3D printer, you will likely be 3D printing your supports using the same filament that your part is made of. For example, if you are printing a PLA model, the supports will also be made from PLA filament. This means that they must be removed manually.
Because most support structures have a low density, it is possible in some cases to simply break them off from your 3D print. This technique does increase the risk of breaking or damaging your 3D printed part. For more precise support removal, you can use a knife, needle-nose pliers or flush cutters to carefully cut and break off the extraneous 3D printed supports. Carefully heating a knife blade can help to seamlessly remove the support from the print surface. The most important thing to keep in mind is to work gently, especially for harder to reach supports.
Once you’ve removed or broken off most of the support structures you can then go over the rough spots with some damp sand paper. This will smooth out the surface where structures were attached and polish the printed part. Alternatively, you can use a solvent, such as acetone or nail polish remover, to smooth out any blemishes caused by support removal.
Recommended reading: Smoothing PLA 3D prints with sandpaper, solvents, and more
Soluble support structures
If you have the chance to work with a dual extrusion 3D printer, support removal can be far easier, requiring little to no manual intervention. This is because you can print with two different types of filament: a classic build material (like PLA or ABS) for your model, and a soluble print material (like PVA or HIPS) for the support structures.
With soluble supports, you simply have to take the 3D printed object from the print bed and submerge it in a liquid bath. PVA filaments will dissolve easily in warm water, while HIPS must be placed in a solution of Limonene. In both cases, it is important not to submerge the parts in water that is too hot, as it can warp the actual model. Keeping the water moving while your part is submerged will also help to dissolve the supports faster. If you are in a particular rush, you can let the supports soften for about 10 minutes and then cut the bulk of them off using pliers. Place the part back in the bath to remove the remaining traces of support.
A final note about PVA is that if your soluble material of choice: be sure to store the filament in a dry place. If it absorbs too much moisture from the air, the filament can clog up your 3D printer nozzle.
Recommended reading: How to Dry Filament
In the end, supports are essential to 3D printing: they let you create complex geometries with overhangs and bridges that would otherwise be impossible to print. This means that, whether you’re a beginner maker or an experienced one, support removal is an important step in the 3D printing process.
 Sculpteo, 2022. “What is important to know about 3D printing supports?” [Internet] https://www.sculpteo.com/en/3d-learning-hub/design-guidelines/understanding-3d-printing-supports/ [Accessed May 19, 2022]
 Ultimaker, March 9, 2022. “Support Settings” [Internet] https://support.ultimaker.com/hc/en-us/articles/360012612779-Support-settings [Accessed May 19, 2022]
 Ultimaker, June 29, 2021. “How to dissolve Ultimaker PVA” [Internet] https://support.ultimaker.com/hc/en-us/articles/360011959100-How-to-dissolve-Ultimaker-PVA [Accessed May 20, 2022]