Raft actually is the horizontal grid of filament that is located under the bottom of the 3D models as shown in the above pictures. The purpose of adding a raft is to ensure that the printed model can attach to the print bed more firmly to prevent the warping issues. Also, raft is useful if the bottom part of the 3D model is small because raft can increase the contact surface between the model and the print bed, which means can let the model stick on the print bed better.  ​

 In the 3D slicing software, Top Solid Layer setting can affect the quality and outlook of the 3D printout. Top solid layer setting is about how many solid layer will be printed onto the top of the model. As we mentioned in the previous articles before, when printing the inner structure of the 3D model, infill with chosen pattern and density will be used, and the top solid layer will be printed on the top of those infill. If the number of the top solid layer is not enough, the infill will be exposed and can be seen from outside and result in what we called pillowing phenomenon as shown below:

Although the lack of enough fill density will also lead to pillowing, how many top solid layers are enough to cover those infill to avoid the pillowing? ​General speaking, it is safer to set the number of top solid layers to be 6. However, the more top solid layers you set, the longer time the 3D printing will take.
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The following is how to set the number of top solid layer in the 3D slicing software Flashprint:

In the 3D slicing software, you will find there is a setting called ”layer height”. Layer height is used to determine the vertical resolution of a printout. The reason why the layer height is called vertical resolution is because the FDM 3d printer print the whole 3d model from the bottom to the top layer by layer. For example, if the layer height is set to be 0.2mm, it means that each layers will be printed in 2mm thickness. Therefore, the smaller the layer height, the higher quality the 3d model will be printed.

The following photo shows different effects when using different layer heights. You can see that the horizontal line pattern on the rightmost printout's surface is less obvious when using smaller layer height. On the other hand, using smaller layer height means that the time consumed to print the 3d model will be much longer.

In general, layer height with 0.1mm to 0.15mm is considered to be high quality, while 0.2mm is regarded as medium quality. It is very easy to set the layer height in the 3d slicing software. Following example shows how to set the layer height in the Flashforge's 3d slicing software Flashprint:

​3d print speed is one of the most fundamental and important settings in a 3d slicing software. The 3d print speed will influence a lot of aspects such as printing quality. This time we are going to talk about how to set the 3d print speed and what is its influence.

​3d print speed setting controls the speed of the print head movement. In general, the normal 3d print speed is around 50 to 60mm/s. The print speed less than 50mm/s can be regarded as slow speed, while more than 60mm/s can be regarded as high speed. ​In most of the 3d slicing softwares, mm/s will be adopted as the print speed unit. For example, mm/s is used in the Flashprint 3d slicing software developed by Flashforge as shown below.

​The print speed we mentioned above of course is only as a reference. This is because the most suitable 3d print speed should be determined by the size, shape and complexity of a 3d model. A faster 3d printing speed may be applicable to a simple cube-like 3d model. However, if there is a detailed decoration on the cube-like 3d model, slower 3d print speed should be used in order to 3d print it with a stable and good quality. Therefore, users may need to test print with different speeds before they are ultimately able to get the quality 3d printed model. Normally, 50mm/s to 60mm/s is a good print speed to start with.

​The 3D print speed which is too fast or too slow does not only affect the 3d printing quality, but may also lead to the following 3d printing problems:
1. 3d printed model warping
2. Under or over extrusion
3. The printing material cannot firmly attach to the build plate when printing the first layer of the 3d model

​Therefore it is very important to get an optimized 3d print speed in order to get a good quality 3d printout.