Everything You Need To Know About Support Structures In 3D Printing

One of the features of additive manufacturing is that it offers great design freedom to create complex and truly impressive parts. However, creating perfect models can require intermediate steps, such as the use of supports. In 3D printing, supports, as the name suggests, are structures that support the unsupported areas of a part. Although at first glance it seems like a simple concept, it can be difficult, especially when it comes to configuring 3D printing supports for your part. Users may have questions such as when they are really necessary, how they can be removed, and what disadvantages their use can have. To answer these questions, we took a deep dive into the effective use of supports in additive manufacturing.

The Choice of Support Structures Depends On the Technology

If you are considering using these supports, the first thing to keep in mind is that depending on the 3D printing technology you use and the complexity of your design, the type of support and function will vary. In FDM 3D printing, for example, there are two general rules you need to know for support structures: the 45-degree rule and the 5-millimeter rule. The first refers to the 3D printer’s horizontal offset between successive layers. So if an overhang of the part tilts at an angle less than 45 degrees from vertical, you can print that overhang without supports. However, if the angle is greater, the machine will not stack the layers properly and the overhang will require support structures. On the other hand, the 5 mm rule states that supports are not required if a bridge (distance between two parallel points on the part) is less than 5 mm, but if it is larger than that then printing problems occur. To connect the two parallel dots without supports, the printer uses a technique called bridging. In this method, the hot material is stretched over short distances to make the connection with minimal sag.

The 45 degree rule applies to 3D extrusion printing.

In contrast, resin 3D printing using processes such as SLA or DLP to produce the final part by photopolymerizing the liquid material using a light source. This technology is one of the most precise, capable of producing the smallest and most complex objects with exact details. It is characterized by the fact that it works in the opposite direction than extrusion, thus the pressure shell is on top rather than the bottom. For this reason, and to ensure that the prints adhere to the platform, these machines almost always require supports. These structures look like thin columns with only a few small points of contact with the model to save on both material and manufacturing time. In this case, the appropriate software can calculate the number of supports, their position, where they touch the part; these factors depend on the complexity of the part in question. With proper post-processing, 3D printing resin with support structures should not affect the quality of the finished part.