Basic Rules of Support Structures

In most cases, supports are designed to hold the material in position for most of the printing. The most important aspect is that they must be easy to remove and should not pose any major drawback in terms of machining time or surface finish defects once removed.

Depending on the kind of design and cost-effectiveness, we need to decide at what points and to what degree support structure must be provided; this should be taken care of during the design of the component.

Typically, if your model includes an overhang or a bridge without underlying support, supports may be necessary for successful 3D printing. The letters Y, H, and T illustrate examples of overhangs and bridges.

Refer the "YHT" Illustration below. **The support material is shown in light gray.**

Not all overhangs require support. The general guideline is that if an overhang is tilted at an angle less than 45 degrees from the vertical, it can typically be printed without supports.

However, overhangs exceeding a 45-degree angle from the vertical need support structures. This is because 3D printers employ a minimal horizontal offset between consecutive layers, which is barely noticeable. As a result, a layer only loads perfectly over the previous one if a vertical wall is present. This allows the printer to handle overhangs that do not deviate significantly from the vertical. The preceding layers can support overhangs at angles less than 45 degrees, whereas those exceeding this angle cannot. Hence, 45 degrees is often considered the threshold for failure.

An FDM printer can easily print the arms of the letter "Y" **without** needing support structures, as these outstretched features do not extend beyond 45 degrees, As shown in the "YHT" illustration above.

Conversely, the overhangs in the letter "T" form a 90-degree angle with the vertical. Therefore, supports are necessary to print the letter T; As shown in the "YHT" illustration above.

The 10 mm Rule on Bridges

Similar to overhangs, not all bridges need support. The general guideline is that if a bridge is less than 10 mm long, it can often be printed without supports. Printers achieve this using bridging, where the hot material is stretched over short distances, allowing the printer to print the bridge with minimal sagging.

However, this technique becomes ineffective if a bridge exceeds 10 mm in length. In such cases, supports are necessary to prevent sagging.

This distance is a general guideline. Adjustments to parameters, particularly active cooling and print speed, can significantly enhance the printer's ability to produce bridges that extend well beyond the 10 mm threshold.

Lets understand this with the letter H. If the central bridge in "H" is less than 10 mm, it can be printed without support or sagging. For bridges longer than 10 mm, support structures become necessary. In the "YHT" illustration provided above, the central bridge exceeds 10 mm, so it is printed with supports.

Here are the appearances of these models when printed. The second image demonstrates the result of printing the letter "T" without support, showing significant sagging on the surface, necessitating extensive post-processing.

Here are the appearances of these models when printed. The first image shows the result of printing the letters Y H T without supports, where the overhang angle of Y is 50 degrees, the bridge distance of H is 11 mm, and the overhang angle of T is 90 degrees, with the length of its arms being 11 mm each. So, with these parameters, the printer was bound to fail, and we can see the mess created. These results are subject to the printer's performance, but the above-mentioned basic rules should be followed with most FDM printers.

The subsequent series of images showcases the same letters Y H T, this time printed with supports. The absence of any printing issues and the expected results underscore the crucial role of supports in determining the success or failure of even the most basic prints.

In the third set of images, we again tried printing Y H T without supports, but this time, we kept the overhang angle on Y at 30 degrees, which is well below the 45-degree mark. We also changed the bridge distance of H to 6 mm, again below the 10 mm threshold mark; and to experiment with the printers ability, we printed the letter T again without supports obviously, but with the length of its arms as 6 mm each, the overhang angle still being the same which is 90 degrees. Ideally, it shouldn't have been printed correctly without support, but the results were surprising as it did a pretty decent job, although it was not perfect. This again shows that support plays a vital role in the print quality.

Shown below is an example of complete failure in printing

Evaluating Your Printer's Performance

The suggested angles for overhangs and bridges are flexible. Your printer's abilities, maintenance, and the type of material being used all play a significant role. Printers that are not well-maintained may encounter difficulties with overhangs at 35—or 40-degree angles from the vertical, while accurately calibrated printers can manage much steeper overhangs and bridges. Therefore, it is a good idea to evaluate your printer's performance before attempting to print intricate models.

By Geometry

There are two common types of support structures: lattice and tree-like supports:

By Ease of Removal

There are two types of supports classified by ease of removal: Break-away and dissolvable supports:

Support Structure Patterns

When you, as the designer, are creating supports, it's crucial to consider the shape's strength, ease of removal, and compatibility. The slicing software provides various patterns and densities with which you can experiment. To adjust the pattern, access the hidden 'Support Pattern' setting in the Settings section to quickly apply this knowledge in your 3D printing projects.

• The Zig-Zag pattern is the quickest to print and the easiest to remove.
• Lines pattern is the next step up. They are relatively easy to remove but slightly more potent than zig-zag patterns.
• Concentric pattern is best for models with shapes near spheres or cylinders. It is more potent than zig-zag and lines.
• Triangle pattern offers great structural strength and is, hence, tough to remove, but since its overall strength is excellent, it is used for many critical sections.
• The Grid pattern is more rigid than lines and zig-zags, offering strong, stable support but more challenging to remove.

Support Structure Density

Like infill density, support density influences speed, ease of removal, and strength in 3D printing.

Disadvantages of Support

Now that we have understood the know-how of supports in 3D printed models let's examine how they affect the final product. Despite their necessity, supports can introduce certain drawbacks that impact the finished model's overall quality, efficiency, and aesthetics. Let's explore these disadvantages in detail.

Note : To avoid such issues, it's best to minimize the use of supports and only add them where necessary. In the following sections, we'll explore how to apply this approach from the CAD design phase through to the printing phase.

Minimize Support Structures Through Design

Minimize Support Structures Through Re-Orientation

Reducing the need for support structures can often be achieved simply by reorienting the model on the print bed. For instance, consider printing an open box with its open face positioned at the top, as shown below.

By strategically adjusting the orientation of your model, you can optimize how layers are built during printing. This can minimize or eliminate the need for support in certain areas.

Moreover, re-orientation affects support requirements and influences other aspects of the print, such as overall strength and surface finish. It's a technique that combines practicality with an understanding of how the printing process interacts with design elements.

Factors such as the intended use, structural integrity, and aesthetic considerations should be considered when re-orienting a model. Experimenting with different orientations during the design phase can significantly improve print quality and efficiency.

How to Remove Breakaway Supports for FDM

Are Support Structure Required for All 3D Printing Tecgnologies?

Most 3D printing technologies require support structures to some extent. The table below shows which technologies require support.

So far, the discussed points primarily pertain to FDM printing technologies. Now, let's explore the roles of support structures in other additive manufacturing technologies.

Role Of Support Structures In Stereo Lithography (SLA) & Digital Light Processing (DLP)

Stereolithography (SLA) and Digital Light Processing (DLP) are advanced 3D printing technologies that create objects from liquid photopolymer resin using a light source to solidify the material.

SLA and DLP printers operate by pulling a model out of a vat containing liquid resin and solidifying it through a light source from below (bottom-up) or submerging the model into the resin. At the same time, the top layer is cured by light from above (top-down).

Support structures, a key component of SLA and DLP printers, are not just essential, but they are also highly efficient.

• They ensure that prints adhere to the build platform and maintain their intended shape during printing.
• These supports are designed as thin ribs, with minimal contact points on the model to conserve material and reduce printing time, providing a streamlined and efficient printing process
• Based on their count, these Supports can be Low, Medium, and High-density.

Despite the need for supports, SLA and DLP technologies are renowned for their high accuracy and can produce intricate and finely detailed objects. Proper post-processing techniques can effectively remove supports without compromising the quality of the final printed part.