Categories: Basics

3D Printing adhesion Skirt, Brim, Raft – The Ultimate Guide

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3D Print Adhesion

What is a 3D Print Skirt?

A skirt is an outline that is extruded on the first layer around a 3D print (but does not touch the actual print). It is one of the 3 types of 3D printing adhesion. The primary purpose of using a skirt is to prime the extruder to ensure the filament is flowing smoothly before actually printing the model. Typically your slicer software will allow the user to select the number of perimeter lines and the distance the Skirt is from the edges of the print. It is important to note that skirt does NOT provide any support for your 3D printed model (compared to Brim and Raft, which are covered next). In addition to priming the extruder, a Skirt is also useful in determining how level the bed and first layer adhesion. A skirt with an even and consistent height that is adhering well to the print bed will help you gain confidence that the print bed is level and that the print will not fail later on.

Typical Skirt Slicer Settings:

​​Skirt Line Count – The number of layers included in the Skirt. For large footprint models, typically 1 Skirt line is sufficient for priming the extruder. For small models, 2-3 Skirt lines will help ensure the extruder is primed well and that the filament is flowing smoothly by the time the print begins.

Skirt Distance – The distance from the innermost Skirt line to the outer-most edge of your 3D print model. This setting is not very critical and it typically ok anywhere from 2-5 mm.

Skirt Advantages

  • Helps to ensure the extruder is primed
  • Helpful to check if the bed is leveled properly
  • Can be used to gain confidence in first layer adhesion (critical for a successful print)
  • Defines footprint of the model on the print bed
  • Uses a relatively small amount of filament

Skirt Disadvantages

  • Does not support your 3D print
  • Although the material usage is small for Skirt, it still consumes material (although it is WELL worth it for all of the Pros listed above!)

3D Print Adhesion

What is a 3D Print Brim?

A Brim is similar to a Skirt, but touches the outer edge of the print and acts as an anchor to the print bed. A Brim consist of multiple perimeter layers that wrap around the first layer of the model and touch the model to provide additional support for the model. Brim is helpful for ensuring good bed adhesion and help to prevent warping (common with filaments such as ABS and prints with high infill density). Similar to Skirt, Brim can be used to gauge first layer adhesion and how level the bed is.

Typical Brim Slicer Settings:

Brim Line Count – The number of layers included in the Brim. Typically 2-5 Brim Lines is sufficient. More lines will provide additional support for the model, but can make it more difficult to remove the part from the print bed when the print is complete.

Brim Width – The width (in millimeters) of the Brim measured from the outermost edge of the first layer of the model.

Brim Advantages

  • Helps to ensure the extruder is primed
  • Helpful to check if the bed is leveled properly
  • Can be used to gain confidence in first layer adhesion (critical for a successful print)
  • Defines footprint of the model on the print bed
  • Uses less filament than a Raft
  • Helps to prevent warping
  • Generally easier to remove print compared to a Raft
  • Maintains a smooth appearance of the bottom of the print

Brim Disadvantages

  • Must be removed from the print after the print is complete, which can create marks on the first layer outer perimeter of the model
  • Uses additional material when compared to a Skirt

3D Print Adhesion

What is a 3D Print Raft?

A Raft is multiple layers of filament extruded in a mesh-like pattern to serve as a supporting base for your 3D print. The first layers of the print are sacrificial and are to be removed when the print is complete. After the Raft is generated, the official first layer of the model will print on top of the raft. The purpose of a Raft is to provide a platform for your model to build upon, and acts as a transition from the print bed to the print. Like Brim, Rafts can be very useful when printing with materials that are prone to warping, and will help with first layer adhesion. Rafts can be useful for prints in which the model is prone to tip over and fail later in the print due to small legs or supports holding the body of the print upright.

Typical Raft Slicer Settings:

Raft Air Gap – This value defines the height of the air gap between the raft and the first layer of the model. Typically a value of 0.1-0.3 mm is sufficient to ensure that the model will stick to the Raft, but will be easily removed upon completion of the print.

Raft Top/Base Layers – The number of layers printed on the Top and Base of the Raft before the model begins. Typically in total you want at least 2 layers to ensure the model will print on a strong base.

Raft Print Speed – The width (in millimeters) of the Brim measured from the outermost edge of the first layer of the model.

Raft Advantages

  • Helps to ensure the extruder is primed
  • Helpful to check if the bed is leveled properly
  • Can be used to gain confidence in first layer adhesion (critical for a successful print)
  • Defines footprint of the model on the print bed
  • Helps to prevent warping

Raft Disadvantages

  • Must be removed from the print after the print is complete, typically creating a rough bottom surface of the model
  • Uses additional material when compared to a Skirt and Raft
  • Typically more difficult to remove when compared to Brim
  • Potential to damage print when removing the Raft

YouTube Link

Click here to learn about other Slicer settings.

This post was published on June 19, 2019

The 3D Print Zone
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