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.
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.
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 in 3D Printing?
A Skirt is a single line of extruded filament around your model. You can choose the number of Skirts in your slicer which would extruder filament over the same area. It doesn’t specifically help with adhesion for your model, but it does help prime the nozzle ready for printing the actual model.
The main purpose of the Skirt is used to make sure that the filament is flowing smoothly before the printing starts.
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
You will find the settings to adjust Skirts, Brims & Rafts under ‘Build Plate Adhesion’ in Cura.
Best Settings for Skirt 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 in 3D Printing?
A Brim is a single flat layer of extruded material around the base of your model. It works for increasing adhesion to the build plate and keeping the edges of your model down on the build plate. It’s basically a collection of Skirts that connect around your model. You can adjust the brim width and line count.
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.
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
Best Settings for Brim in Cura
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 depending on how it performs at 0mm.
What is a Raft in 3D Printing?
A Raft is a thick plate of extruded material beneath the model. It has the effect of reducing the effect of heat from the build plate onto your model, as well as providing a sturdy foundation of material to stick to the build plate. These work very well for build plate adhesion, the most effective of all three types.
For materials that are known to warp and pull away from the build plate, using a raft is a great preventative measure to take, especially for filament like ABS or Nylon.
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.
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 a 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
Best Settings for Raft in Cura
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 its 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. Its 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. Its 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 to 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 a 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.