Skirts, Rafts & Brims, terms you’ve probably in your time 3D printing. It can get confusing at first when you haven’t gone into detail about just what they are, or what they are used for. They have their purpose and are pretty simply to understand.
Skirts, rafts and brims are used to either prime the nozzle before building up the main print, or to help your prints stay stuck down on the bed, otherwise known as increasing bed adhesion. Most people always use a skirt to prime the nozzle, while brims and rafts are less common and provide a good foundation layer for prints.
In this guide, we are going to talk about the base layer techniques to increase the quality of the 3D print. You will have a good amount of information about skirts, rafts and brims through this article.
Quick Brief on Skirts, Brims & Rafts
When printing a 3D model, the first layer or the base layer is very important, it gives us a better chance to get a print safely to the end, so we aren’t wasting precious time or filament.
Skirts, Rafts, and Brims are the different base layer techniques used to print your 3D model with better success.
These techniques are popular and useful to us because they give a stronger base and make the filament flow smoothly after laying the base layer, which then hopefully adheres correctly.
In other words, the skirt is used as a primer to make sure your nozzle is laying down material accurately and precisely before printing your main model.
Brims and Rafts specifically, are similar in the way that they act as a sort of foundation for your 3D parts.
Having a bad initial layer or foundation can end up in a print not sticking down to the bed properly, especially with models that don’t have a flat side. This base layer is perfect for these types of prints, so they definitely have their use.
In most cases, with a simple 3D print, a Brim or Raft isn’t needed, but they can add that extra bed adhesion if you are having problems in that area.
Detailed Information on Skirt, Raft, and Brim in 3D Printing
Keep on reading to get the answers to all the questions you are looking for regarding Skirt, Raft, and Brim the base layer techniques.
What is a Skirt?
Here is a picture of a Skirt in Cura:
A skirt is a baseline that is extruded around a 3D print in the base layer but does not apply to the actual print. The Skirt is one of the three adhesion techniques of 3D printing.
The main purpose of the Skirt is used to make sure that the filament is flowing smoothly before the printing starts. Your slicer software will help you select the boundary lines and the distance of the skirt from the 3D print edges.
A skirt with a uniform and constant height, that is fixed well to the printing platform will help you get a good 3D print.
Usage of Skirt in 3D Printing
Let’s take a look when you can use the Skirt.
- The Skirt is used to make the flow of the filament smooth for the main printing
- It can be used anytime since it uses a small amount of filament and makes the flow smooth
- You can use to level the printing bed for the 3D model
Settings Adjustment for a Skirt
You will find the settings to adjust Skirts, Brims & Rafts under ‘Build Plate Adhesion’ in Cura.
The skirt is the simplest technique comparing to the others, so there are not many settings to adjust.
Follow these setting adjustments for Skirts:
- Build Plate Adhesion Type: Skirt
- Skirt Line Count: 3
- (Expert) Skirt Distance: 10.00mm
- (Expert) Skirt/Brim Minimum Length: 250.00mm
This is pretty self-explanatory, the ‘Skirt Distance’ is how far away the skirt will print around the model. The ‘Skirt Minimum Length’ is how much length your printer will extrude as a minimum before printing your model.
What is a Brim?
Here is a picture of a Brim in Cura:
The Brim is a special type of skirt that connects the edges of the 3D print. Typically, a Brim with a larger number of outlines is printed to form a large ring around the 3D model.
The Brim is mostly used to hold the edges of the model, which help prevent warping and make it easier to stick to the bed.
Brim can be the preferred Raft option because the Brim can be printed very fast and uses less filament. After printing, the thin frame can be removed from the solid pattern easily.
Usage of Brims in 3D Printing
You can use Brim for the following purpose:
- To avoid the warping in the printed model when using the ABS filament
- To get good platform adhesion
- Brim can be used to add the safety precaution for the 3D print that requires strong platform adhesion
- Also used to add support to the 3D models with the small base design
Settings Adjustment for Brim
Brim can only be separated from the Skirts by the settings.
Follow these setting adjustments for Brims:
- Build Plate Adhesion Type: Brim
- (Advanced) Brim Width: 8.00mm
- (Advanced) Brim Line Count: 5
- (Advanced) Brim Only on Outside: Unchecked
- (Expert) Skirt/Brim Minimum Length: 250.00mm
- (Expert) Brim Distance: 0
A ‘Brim Line Count’ of at least 5 is good, add more depending on the model.
Checking the ‘Brim Only on Outside’ setting reduced the amount of brim material used while not reducing bed adhesion by much.
Adding a few (mm) to the ‘Brim Distance’ can make it easier to remove, usually 0.1mm is good enough.
What is a Raft?
Here is a picture of a Raft in Cura:
The Raft is a network of horizontal filaments that lie under the 3D model. Your 3D model is printed on this Raft, instead of on the surface of the building platform.
Rafts are mainly used with ABS to facilitate warping and sticking to the bed.
However, they can also be used to stabilize models with small base prints or to create a solid foundation for creating the top layers on your model. After printing, the Raft is easy to remove from the 3D model.
Usage of Raft in 3D Print
There are several uses of Raft in 3D print:
- The Raft is used to hold the large 3D models
- It is used to prevent the warping in the 3D print
- It can be used if the print keeps falling off
- Best to provide adhesion on glass platform because the glass platform is less adhesive
- Used in the tall prints that need support
- It can also be used to the 3D models with a weak base or small lower part
Settings Adjustment for Raft
Follow these setting adjustments for Raft in 3D print:
- Build Plate Adhesion Type: Raft
- (Expert) Raft Air Gap: 0.3mm
- (Expert) Raft Top Layers: 2
- (Expert) Raft Print Speed: 40mm/s
There are a little too many expert settings for the raft, which don’t really require adjusting. If you find your raft is too hard to remove from the print, you can increase the ‘Raft Air Gap’ which is the gap between the final raft layer and first layer of the model.
The ‘Raft Top Layers’ give you a smoother top surface which is usually 2 rather than one because it makes the surface fuller.
The ideal ‘Raft Print Speed’ is fairly slow so it’s done with accuracy and precision. This leaves little room for error for the foundation of your print.
Differences in Material & Time For Skirts, Brims & Rafts
As you can guess, when you use a Skirt, Brim or Raft, the bigger the object, the more material you will use.
A skirt only outlines the object generally three times, so it uses the smallest amount of material.
A Brim outlines and surrounds your print object a number of specified times, default being around 8 times so this uses a decent amount of material.
A Raft outlines, surrounds and props up your print object, using around 4 layers before printing the rest of the object. This uses the most material, especially when it’s base is large.
I’ll use a visual example of how this makes a difference in material used and printing time.
The following is a Skirt, Brim & Raft for a simple, low-poly vase. It’s dimensions are 60 x 60 x 120mm.
Raft – 60g
Brim – 57g – 3 Hours 33 Minutes – Brim Width: 8mm, Count: 20 (Default)
Skirt – 57g – 3 Hours 32 Minutes – Count: 3 (Default)
The following is a Skirt, Brim & Raft for a leaf. It’s dimensions are 186 x 164 x 56mm
Raft – 83g – 8 Hours 6 Minutes
Brim – 68g – 7 Hours 26 Minutes – Brim Width: 8mm, Count: 20 (Default)
Skirt – 66g – 7 Hours 9 Minutes – Count: 3 (Default)
There is a much wider difference in material used and printing time between these as you can see visually.
Depending on the orientation you use for your model, you could manage to use a smaller skirt, brim or raft but there are always a number of factors you have to balance before choosing the best orientation.
I personally recommend everyone to be making use of at least a Skirt, for every print because it has the benefit of priming the nozzle and giving you the opportunity the correctly level the bed.
For Brims & Rafts, these are used at your discretion mostly for bigger models that might have trouble with bed adhesion. Definitely use it a few times so you can get a feel for how they are useful in your 3D printing journey.
I don’t really make use of Brims & Rafts and rafts much unless I’m doing a large print which is going to be at it for several hours.
Not only does it give a strong foundation, but gives you piece of mind that the print won’t get knocked off the bed accidentally.
There isn’t usually too much of a trade-off, maybe an extra 30 minutes and 15 grams of material, but if this saves us having to repeat a failed print, it works out in our favor.