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Fillet vs. Chamfer in 3D Printing: Differences and Functions

If you are into design and 3D printing, you will have most likely heard of fillets and chamfers. When asked what the differences between the two are, you may think it’s very straightforward — the fillet has a rounded edge while the chamfer is sloped or angled. However, it is far more complex than that. 

Fillets and chamfers are different since they oppose each other geometrically and have different functions in 3D design. Fillets are rounded and distribute stress evenly over a larger area, whereas chamfers are angled and best suited to low-stress concentrations. 

In this article, I will explain the differences and functions of fillets and chamfers. I’ll also help you understand when you should choose one over the other and the benefits of doing so. Let’s get started! 

Differences Between Fillets and Chamfers

Fillets and chamfers are two different ways to form edges or joints on your 3D prints.

To give you an idea of the difference between fillets and chamfers, look at your workstation. The 45-degree beveled edge of your laptop is an example of a chamfer, while your rounded mouse is an example of fillets. 

3d design cube with a fillet and a chamfer
3D Designed Cube with Fillet and Chamfer

Chamfers create nice-looking corners, prevent borders from being damaged, and allow parts to fit into one another more uniformly. These edges are sharp and clean-looking, but they may make your print less comfortable to hold in your hands. 

At the same time, fillets produce rounded, more durable, and arguably more aesthetically pleasing edges. These edges are safer and more comfortable to handle, though they may be more challenging to print since you must work with curved edges. 

Choosing between the two depends on your design’s aesthetic and purpose. 

Comparing Fillets and Chamfers in 3D Printing

So, let’s get down to the details and look a the most noticeable differences between these two edges: 

FeatureFillets Chamfers 
Stress ConcentrationAble to withstand high levels of stress.
Reduces stress on a broad surface
Poor stress resistance

Unable to widely distribute stress
SafetyRounded edges are safer to handleSharp edges can be hazardous
Printing timeMore printing time
Curved edges are more complex to produce 
Less printing time
Angled edges are simple to make
AttractivenessAesthetically pleasingSimple design
Pro’s and Cons Chamfers vs Fillets

Let’s discuss these differences in more detail.

Stress Concentration

Fillets are known for handling high-stress concentrations and therefore are the best choice for 3D printed parts that may need to endure pressure. As the fillet can share stress over a larger area, it can considerably reduce the chance of bowing, warping, and cracking due to stress. 

Although chamfers can also handle stress, the amount they can take on is much less. They are unable to distribute pressure evenly, which could cause material deformation. Chamfers are best suited to product edges.

Safety

Fillets are rounded and very aesthetically pleasing. They are smooth to the touch, and due to their roundness, they have no sharp or pointed edges that could cause harm. 

Chamfers are angled, usually at 45 degrees (sometimes 60 degrees), and are notably sharper. For that reason, chamfers don’t have the same hand-feel as fillets, and they can be sharp enough to hurt your skin. So, they’re not ideal for prints like tools. 

Printing Time

The rounded edges of fillets are time-consuming to make, mainly because 3D printing is an additive process. Fillets require precision, as the radius needs to blend seamlessly into the sides and faces of your walls. So, one loose layer or string can have a noticeable effect on your print’s quality.  

You must program your printer to produce small layers to achieve a high-quality fillet. On the other hand, chamfers don’t need such accommodations, making them significantly quicker to produce. 

Attractiveness

Industrial Designers typically prefer using fillets for their products because the rounded shape is pleasing to the eye.  

Chamfers are basic-looking and are not often thought of when creating beautiful design features. They are used more for practicality.

Functions of Fillets and Chamfers

Although both chamfers and fillets are used in 3D printing to cover or protect raw edges, their functions are surprisingly different. Making the correct choice between the two will significantly affect your design’s performance and the overall usage of materials. 

If the exterior of your product isn’t crucial to your design, then you can choose a simple chamfer to cover the sharp corners. If the product’s exterior is essential to your design, you should opt for a more attractive fillet.

Choosing Between Fillets and Chamfers in 3D Printing

When 3D printing your product, you must keep various things in mind, such as cost, time, and aesthetics. Let’s discuss when you should choose chamfers or fillets and why.

  • Inside Edges. To avoid any accidents when handling the product, you will probably want to choose a fillet for the edges. Chamfers are sharper and may result in injury if handled too much or incorrectly. 
  • Outside Edges. The choice here really depends on the design style. What do you want it to look like? If you simply want to soften the edges slightly, you can opt for economical chamfers, but if your design requires very rounded edges, you will need to choose the more expensive fillets. For a superior design, you will need to increase the radius of the fillet, so keep costs in mind here. 
  • Holes. If your product design has a hole in which bolts or screws need to be driven, using a chamfer will make the most sense. The sharp edge of the chamfer will allow for smoother pin movement down the hole, resulting in effortless fastening. Fillets generally prevent smooth movement into a hole.  

Conclusion

Now that you understand the key differences and functions between fillets and chamfers, it should make a choice between them much more manageable. Depending on your need, you can use either one to cover the edges of your design. 

Opt for a fillet if you require a more aesthetically pleasing look for your 3D printing design. If costs and time constraints are more important, then chamfers are the way to go.