What is a 3D Printing Brim?

A 3D printing brim is a layer of material that extends along the print bed from the edges of a 3D print. Brims help to improve bed adhesion and to prevent warping.

Unlike a raft, a brim doesn’t reach below the print. In this way, it can also be thought of as a skirt that doesn’t touch the edge of the print.

Many users depend only on a raft to improve their chances of a successful print, but a brim can be just as useful. In fact, in many cases it is better than a raft. That’s because it’s easy to remove, wastes less material and doesn’t affect the bottom layer finish of the print.

When to Use a Brim

Warping: As a 3D printing brim functions similar to a raft, it is also recommended to be used while printing with ABS. ABS filaments are prone to warping issues, which a brim can reduce by holding onto the outer layer of the print and keeping it firmly in place.

Poor Bed Adhesion: A brim is attached to the outer edges of the print and its width is adjustable. The brim line count around the print increases the surface contact with the build platform thereby improving the bed adhesion. Increased bed adhesion results in higher percentage of successful prints.

Risky Prints: As a safety measure, a brim can be added to every print to ensure better bed adhesion. It is not required while printing with filaments like PLA but, since it’s easy to remove, adding one doesn’t hurt.

Weak Supports: In cases where prints are big and require support only for a small part at the top of the print, the support structures created are really tiny and these structures can easily break while printing. Therefore it always helps to provide support for the support structures.

Narrow Base: Brims should also be used for prints with a narrow base like a tower or a char. This helps increase the strength for the entire structure.

Pros & Cons of 3D Printing a Brim

Like every technique, a 3D printing brim also has a few pros and cons.

Pros:

Prevents warping issues with materials like ABS

Improves bed adhesion leading to higher chances of a successful print

Comparatively easy to remove when compared to a raft

Doesn’t interfere with the bottom layer of the print

Uses less material compared to a raft

Cons:

Produces a small amount of waste material

Touchpoints must be sanded to get a smooth surface finish

Possibility of breaking the part while removing the brim

Slicer Settings for 3D Printing a Brim

Generally, we can control two important settings for brims: brim width and line count.

Brim width is defined in millimeters while line count is the number of contour lines in the brim. The more the lines, the better the strength will be, up to a certain distance. However, it also becomes harder to remove the brim from the print.

A commonly used brim line count is three to five lines around the print. This gives a good result but should be modified depending on the design, bed temperature and printer.

Note: The settings shown in the above image are not practically used, they are just for representation.

Summary

Requiring less effort than rafts and providing much more support than skirts, brims are a strong go-to option. For a small amount of extra waste material, a 3D printing brim can do a lot to mitigate problems with bed adhesion and warping.

And because it doesn’t reach under the 3D print, post-processing is much easier than with a raft. While not always necessary, 3D printing a brim is definitely a good idea if you have even a small amount of doubt.

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By Abhimanyu Chavan

3D Printing Brim – When Should You Use It