In the field of printing, 3D printing has developed into a revolutionary production method. However, even the most advanced 3D printers will encounter various technical challenges in actual operation. The adhesion issue between the printout and the printing platform is one of them. To address this technical issue, the raft emerged as a clever solution. In this blog, we will provide a detailed introduction to the definition and function of the raft, the specific method of adding a raft in slicing software, and the factors that must be weighed when using it.
Table of Contents
- What is a Raft in 3D Printing
- Why Use a Raft in 3D Printing
- How to Add a Raft in 3D Printing
- The Trade-offs of Using a Raft in 3D Printing
- Frequently Asked Questions about Rafts in 3D Printing
What is a Raft in 3D Printing
A raft is a temporary support structure specially generated between the model and the printing platform during the 3D printing process. Morphologically, it usually presents as a thin layer base in the form of a network or grid. Its physical properties are similar to those of the foundation in buildings or the floating raft of ships, thus it is named "raft". This structure is not part of the final model but an auxiliary construction that needs to be removed after printing is completed.
Why Use a Raft in 3D Printing
1. Enhance Adhesion and Prevent Warping
One of the most common technical challenges in 3D printing is that the printed parts fall off or warp from the build platform. This phenomenon is particularly evident when printing large flat structures or using highly shrinkable materials such as ABS and nylon. The raft expands the contact area, enabling the model to firmly adhere to the platform until the printing is completed and completely cooled.This makes the raft an important aid in professional-grade 3D printing, especially in industrial applications.
2. Solve the Problem of Uneven Platform
Although the construction platforms of modern 3D printers already have a high degree of flatness, there may still be tiny depressions or uneven areas on the platform surface during long-term use or in low-cost devices.These small defects will lead to uneven printing of the first layer of the model, and then affect the overall printing quality.
As a "sacrificial layer", the raft can compensate for the irregularity of the platform surface and provide the main body of the model with a nearly ideal flat starting surface. This compensation mechanism effectively reduces the direct impact of equipment accuracy on print quality.
3. Protect Model Integrity
For models with fine bottom structures or extremely small contact areas, direct printing on the build platform may cause two problems.
- A: It is difficult to achieve sufficient adhesion
- B: It is easy to damage the bottom details of the model when removing it.
In this case, the raft can act as a buffer layer. It not only ensures the stability during the printing process but also enables the model to be relatively easily separated after printing is completed. This method has particularly significant application value in resin 3D printing and the manufacturing of precision parts.
How to Add a Raft in 3D Printing
You can learn the specific process of adding a raft through the following video. In addition, we'll also give you some general steps.1. First, you need to import the 3D model into the slicing software. Although the interfaces and terms of different software may vary slightly, the basic path is the same.
2. In the Settings, you need to find the option bar related to the Build Plate Adhesion or Enable Support.
3. You can see several options about support structures: None, Skirt, Brim, and Raft.
4. Please click on "Raft". Once clicked, the software will automatically generate a grid-like platform at the bottom of your model.
5. After selecting the raft, you can expand the Advanced Settings to optimize the printing effect. Several core parameters are as follows:
- Raft Top Layers: Controls how many layers the model prints on (2-3 is common for a smooth bottom). Appropriately increasing the thickness can better compensate for the unevenness of the platform, but it will be more difficult to remove, consume more materials and time.
- Raft Base Layers: Sets the number of solid, dense layers at the very bottom of the raft that contact the build plate (typically 2 layers). Its purpose is to create an extremely strong, anti-warping bond with the build surface. Increasing this value enhances adhesion (crucial for warpy materials like ABS) but makes the raft harder to remove from the plate.
- Raft Air Gap (Separation Distance): This is the air gap between the top layer of the raft and the first layer of the model. Appropriately increasing the gap will make it easier to peel off the raft after printing, but it may slightly affect the smoothness of the bottom of the model. It is usually around 0.1mm, for easy separation.
- Raft Extra Margin: It refers to the width by which the raft outline extends beyond the edge of the model. Increasing the extended distance can provide stronger adhesion and stability, especially suitable for large models that are prone to warping. (e.g., 15mm makes a 20mm raft 35mm wide).
- Raft Print Speed: Slower speeds (especially for the first layer of the part on the raft) improve adhesion and release.
6. Please Note: In practical applications, if you are not sure of the specific values, please use the default or recommended parameters when printing for the first time. Then you can adjust 1 to 2 of the most critical parameters based on the print result. By this method, you can find the optimal raft configuration for specific printers, materials and models.
The Trade-offs of Using a Raft in 3D Printing
While fully recognizing the functional value of the raft, we also need to objectively recognize the additional impacts it brings. Choosing to use the raft means that one needs to proactively accept the following trade-offs:
1. Impact on the Bottom Surface of the Model
After adding a raft, the bottom surface of the model will inevitably be marked by the texture of the mesh. This relatively rough surface texture is different from the smooth effect obtained by directly printing on the platform. Therefore, if the bottom surface of the model is part of the appearance display or a high-precision flat fit is required during assembly, you need to carefully consider whether to add a raft.
2. Additional Material and Time Investment
Generating the raft itself consumes additional wire and increases the overall print time. This increment may not be obvious for small-scale printing, but when it comes to large-scale or batch printing, the accumulated material cost and time cost will become significant. From the perspective of printing efficiency, this is an investment made to increase the success rate.
3. An Additional Post-processing Step
After printing is completed, separating the raft is a step that needs to be done manually. It requires the operator to have certain skills and patience. If not handled properly, there is a risk of damaging the bottom of the model.
The use of rafts in 3D printing is essentially a trade-off made among the stability of the printing process, the quality of the bottom surface, the printing cost and the simplicity. It is wise to enable it only in necessary scenarios (such as dealing with warping materials or uneven platforms), thereby maximizing its benefits and managing the related costs well.
Frequently Asked Questions about Rafts in 3D Printing
1. Does the thicker the raft, the better the 3D printing result?
No. In fact, overly thick rafts not only waste materials and time but may also lead to heat accumulation problems, thereby increasing the risk of warping. It usually does not exceed 5% of the model's height.
2. Is a raft necessary in the 3D printing process?
No, the raft is not an indispensable part of the 3D printing process. Materials that are easy to print, such as PLA or PETG, usually do not require rafts on well-leveled platforms. In addition, if the model itself has a wide flat base, it may not require a raft for bonding or support. Excessive use of raft layers will unnecessarily increase costs and time. You can decide whether a raft is needed based on the specific model and the printing platform.
3. Can rafts solve all adhesion problems in 3D printing?
No, the raft is just one of the solutions. It cannot replace good platform maintenance, correct temperature settings and appropriate model design. The best results can be obtained by combining multiple techniques.
Summary
Raft, as a key technology in 3D printing, plays an irreplaceable role in improving the success rate and quality of printing. From a simple mesh base to an intelligent multi-functional structure, it is also constantly evolving and improving itself. Understanding the meaning of the raft and mastering its parameter optimization methods can significantly enhance the efficiency and quality of 3D printing. It has significant practical value for both amateurs and professional manufacturers. But as we mentioned before, the raft is not an essential part of the 3D printing process. Whether to add a raft or not, please choose according to your actual situation.
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