Rafts, Skirts and Brims!
- Cura comes with a convenient Custom Settings panel that enables you to fix most of those problems by making various adjustments. Among those settings, you'll find Quality, Material, Speed, Cooling, and more. When you explore each category, you'll find the customizable settings.
- Wall Thickness This setting controls how thick the exterior shell of the model is (top and bottom not included here). The value of this setting should be equal to the size of your printer's nozzle multiplied by an integer. Therefore, if you have a 0.4mm nozzle and set the thickness to 3, you'll end up with three shells (3.0.4). Under normal circumstances, you don't need to set the value.
Under brim settings there is an offset option that value specifies if it touches or not. Should be zero to touch. Also make sure you are selecting to print a brim and not a skirt. A skirt does not touch and is meant mainly just to get a good flow before printing. Like it or not fnaf.
This tutorial will help you understand the differences between rafts, skirts and brims. All three techniques provide a starting point for your 3D printed models, but they have different uses and advantages.
Rafts
A Raft is a horizontal latticework of filament that is located underneath your part. Your 3D printed part will be printed on top of this raft, instead of directly on the build platform surface. Rafts are primarily used with ABS to help with warping and bed adhesion, but they can also be used to help stabilize models with small footprints, or to create a strong foundation on which to build the upper layers of your part. The raft included in Simplify3D has been optimized over years of testing on hundreds of different machines to ensure easy separation and a high-quality surface finish on the bottom of your part. Once the print is complete, the raft effortlessly peels away from the print and can be discarded.
For our example today, we are going to add a raft to the popular 'Dodecahedron' model. First, download and import the STL file from here. Then click 'Edit Process Settings' in Simplify3D and place a checkmark beside the 'Include Raft' option. The software also includes many settings that allow you to customize the raft for faster print times or improved adhesion. To adjust these setting, click on the 'Show Advanced' option in the bottom left of this window and then go to the Additions tab. This tab contains the settings for the raft, as well as the skirt and brim which we will discuss shortly. An explanation of the important settings are given below:
- Raft Top Layers – The number of interface layers that are printed at the top of the raft. Your model will be printed on top of these layers, so you usually want at least 2-3 layers to ensure a smooth surface.
- Raft Base Layers – The number of extra-thick layers at the very bottom of the raft. These layers are printed slow and thick to ensure a strong bond to the build platform.
- Raft Offset from Part – How wide the raft will extend beyond the edges of your part
- Separation Distance – This is an important setting that defines the height of the air gap between the raft and your part. Typically, having a gap of at least 0.1mm will help keep the part connected to the raft,
while still allowing for easy separation once the print is complete. - Above Raft Speed – Use this setting to customize the speed of the first layer of your part that is printed on top of the raft surface. Using a slow speed for this layer will also help the part stay attached to the raft during the print.
Cura Brim Vs Skirt
Adjust any of these settings and then click OK to save your changes. Click 'Prepare to Print' to use the realistic pre-print simulation in Simplify3D to view an animated preview of the exact settings that you changed and how they will affect the print. Once you are happy with the changes, you can try running a test print on your 3D printer. Seagate thunderbolt enclosure.
When the print is completed, remove the entire raft and model from the build platform. You can then grab the raft and begin to peel it away from the part, leaving a high-quality surface finish on the bottom of your print. Usually, this can be done by hand, but for extra delicate parts, you may want to use a thin spatula or tweezers to help with the removal. If you find you are having a difficult time removing the raft from the part, you can try increasing the raft separation distance or altering the other settings explained above.
Skirts
A skirt is an outline that surrounds your part but does not touch the part. The skirt is extruded on the print bed before starting to print your model. Skirts serve a useful purpose because they help prime your extruder and establish a smooth flow of filament. Observing the skirt also allows you to detect and adjust any leveling or adhesion issues before the actual model begins printing.
You can customize your skirt by adjusting the settings on the Additions tab. This allows you to adjust the skirt position, the amount of plastic that is primed, and even the extruder that is used for the skirt.
- Skirt Extruder – Choose the extruder that will be used to print the skirt. This allows you to prime different extruders at the start of your print. If you want to prime all of your extruders, select the 'All Extruders' option.
- Skirt Layers – How many layers you want to include a skirt. Typically, 1 layer is enough to prime the extruder, but adding a 2nd or 3rd layer may help create a more robust skirt that can be peeled away from the bed easier.
- Skirt Offset from Part – How far away the skirt should be from the edges of your part
- Skirt Outlines – How many loops you want to print around the outline of your model. Increase this value if you need to prime your extruder more by extruding extra filament.
Brims
A Brim is a special type of skirt that is actually attached to the edges of your model. Typically, the brim is printed with a increased number of outlines to create a large ring around your part, similar to the brim of a hat. Brims are often used to hold down the edges of your part, which can prevent warping and help with bed adhesion. The Brim may be a preferred option to the raft (which also helps with adhesion), as the brim can typically be printed much faster and uses far less filament. Once the print is complete, the thin brim can be separated from the solid model and discarded.
Because the Brim is a special type of skirt, it uses many of the same settings explained in the previous section. To setup a Brim in Simplify3D, set the skirt offset to 0mm so that the brim will be touching the edges of your model. Then increase the number of skirt outlines to 5 or more to create a wide ring around your part. You can raise the number of outlines even further if you need to increase the surface area of the brim for extra adhesion. Now when you start your print, the brim will serve as both priming and an adhesion assistant!
After the print is complete, the thin brim should easily peel away from the solid part. If you find that the brim is attached too firmly, you could increase the skirt offset slightly to 0.1 or 0.2mm to add a small gap between the brim and the part.
Now you know 3 new techniques to help improve the foundation of your 3D printed parts! Next time you are struggling with adhesion, priming, or small delicate parts, you will know the exact technique to use.
More Tips to Improve Your Prints
If you want even more tips on how to improve your 3D printed parts, be sure to check out our extensive Print Quality Guide. This guide covers dozens of common issues and provides tips and suggestions for each one, giving you the knowledge you need to succeed.
3D printer bed adhesion is the foundation of a successful print, but there are circumstances that make adhesion a challenge, even if your PEI surface has been properly maintained.
- 3D models don't always load in Cura LulzBot Edition with the optimal orientation for printing
- Some 3D models lack a flat surface or obvious base
- Some models have minimal surface area for bed contact in any orientation
- Certain filament materials are more prone to warping or curling
The following LulzBot 3D printer tips and tricks will help you improve those challenging 3D prints by maximizing print bed adhesion during the printing process.
Models do not always load in Cura LE with the optimal orientation. Before you begin printing, it's always a good idea to consider how rotating your model could potentially improve bed adhesion and overall print quality. Your goal is to maximize print bed contact and layer bonding while minimizing the number of overhangs and bridges.
Note: The maximum overhang angle your LulzBot printer can successfully produce is a factor of the material being used, the layer thickness, the cooling fan speed, and the tolerance for surface imperfections for a given use case. If you're not sure how shallow of an angle the filament can handle, try printing an overhang angle test object.
- In Cura, select your model, then select the Rotate icon on the left-hand side of your screen.
- The Rotate tool gives you the ability to orient your model along three axes. The red circle will allow you to rotate around the X-axis. The blue circle will rotate around the Z-axis. The green circle will rotate around the Y-axis.
- When you've found the optimal side to print as the base, use the Lay Flat icon to ensure that the flat portion of your print is securely attached to the print surface. It is highly recommended to use this option after rotating your model on the Z-axis as it will help prevent adhesion issues during the print.
Note: Adding brim to your print can help improve adhesion as well. Brim adds concentric perimeters around the base of the print, better adhering the print to the heated plate. This is only one layer thick, and easily removed post-print. To add Brim to your print, select Custom Print Setup, and then select Brim under Build Plate Adhesion Type.
Tricks for Improving AdhesionBy altering the model itself, you can be much more selective in how the model is printed. Here are four methods to get you started manually altering your models.
1. Drop the Base
Depending on how you intend to use your printed object, you can lower the model's Z-axis in order to create a greater surface area in contact with the bed. The model will lose some of its height but will widen the base in the process, stabilizing the print with improved bed adhesion.
This technique works well for organic shapes likes models of bones, artifacts, and sculptures. Spheres are a good example because Cura shows the section of the model that is too steep to print in red. Simply select the blue Z-axis arrow and move your model downwards slowly until the red area is underneath the print surface, creating a 30 degree print angle or less.
2. Divide and Conquer
You can use a similar technique to effectively cut your model in half, and then bond the halves together with glue. Using this technique, your model won't have an artificial flat surface, but will have a glue seam.
Take note of the the total height of the Z-axis by selecting the model and then Scale. Divide the number in half and write it down. Then select Move, and enter the number into Z as a negative value. You should now see half of the model pushed down below the print surface.
If your model is symmetrical all around, like a sphere, simply right click the model and make a duplicate, and repeat dividing it in half.
If your model is asymmetrical, right click the model and make a duplicate, then rotate the duplicate 180 degrees along the Y-axis, until it's completely upside down. Type in a negative Z value for half the Z-axis of your object, and hit enter.
Cura Brim Settings
3. Mouse Ears
Cura Brim Settings Image
*requires modeling software
Mouse ears are an excellent method for increasing adhesion of warp-prone materials like ABS or Nylon, particularly if your model has limited print surface contact. Note that the mouse ears will need to be manually cut off of your model after printing.
Download a mouse ears stl file, then in your modeling software, place the single-layered discs (mouse ears) through areas with poor print adhesion. Make sure the mouse ears are a single-layer tall, and then center the mouse ears around any section of the your model that might warp during printing. This added layer will create a greater bond to keep the print steady and help prevent warping.
Using this L-shaped pipe model as an example, take a moment to imagine how the tool head would move during printing. From the bottom up, layer by layer, you can tell the print would have difficulty adhering to the bed because there isn't a flat base to build on. What a perfect opportunity to use one of the techniques discussed earlier!
Drop The Base wouldn't be appropriate here because the model is mechanical, and altering the shape would affect the functionality. Instead, try the Divide and Conquer technique - sinking half the model through the surface, duplicating, rotating 180 degrees if needed, moving the halves apart, printing, and the adhering the halves together. Once this has been set up in Cura, adding Brim to the Build Plate Adhesion settings will help ensure that each half maintains a strong bond during printing.
Cura Add Brim
Step 1: Rotate model to find optimal side
Step 2: Calculate half the Z-axis height
37.7734/2 = 18.8867
Step 3: Select Move, and in the Z field, enter half the Z-axis height as a negative value
Step 4: Right click the model, Select Multiple Selected Model, and select 1 for Number of Copies
Step 5: Enter in negative value for half the Z-axis height
Docker high image disk utilization. Step 6: Select Brim for Build Plate Adhesion
Step 7: Remove print, trim brim off the prints, and adhere sides together
Related Products