Design Tips From 3D Printing Specialists : Utilize Rafts, Brims and Skirts

Rafts, brims (sidewalks) and skirts are an easy way to get better results when you print. One of the easiest ways to prevent poor bed/build plate adhesion, along with print warping, is to utilize rafts, brims and skirts.

What is a Raft?

Rafts are a throwaway horizontal surface that sits under your object and extends a specific distance away from the sides of your object. Due to its larger surface area, the raft greatly improves  adhesion and reduces warping in the object itself, since the edges of the raft are much more likely to warp, leaving the bottom of the object level and square. A raft can also be used to provide greater stability to objects that have small footprints or objects that may tend to be top heavy or larger. The photo below shows what a raft would look like when 3D printed. 

What is a Brim?

Brim (also known as sidewalks) are a close relative of rafts. A brim only extends outward from the perimeter of an object (think of the brim of a hat), it has no contact with the object’s underside. For smaller or more delicate objects, a brim may be preferable to a raft due to the fact that it's only contact with an object is along the outside edge in a very thin layer. Support structures, that tend to be narrower and have a low surface area on the bed, can easily pop off the bed, so it’s wise to print supports with brims. The photo is an example of what a brim looks like in a 3D printer. 

What is a Skirt?

A skirt is nothing more than a brim that doesn’t touch the edges of the object that you’re printing. Skirts serve a useful purpose because they help prime the extruder and establish a smooth flow of filament. Most 3D print slicing software will automatically add a skirt to the beginning of each print. Skirts are usually just a couple of layers thick and can be used in multiple ways (i.e. preview of how a 3D printer is working/how material is flowing, thermal barriers etc.) As you can see in the photo below, there is a thin skirt printed around the print job. 

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