3D printing design guide.
Printing recommendations.
For a printout successful is necessary to some rules for parts that want to be 3D printed.
1.
Wall thickness.
Wall thickness is the distance between one surface of the pattern and the opposite surface next to it. For a good result and a durable product, it is recommended that this thickness should not be less than 1 mm.
2.
Surface quality and part orientation.
The way the pattern is printed determines several characteristics of the pattern, one of which is its surface quality. This is because the pattern is printed layer by layer, so the orientation of the part when it is printed will determine its surface quality. The same part printed with a different orientation will have a different finish.
An example of this can be seen in the image above. On the left, the piece is printedă horizontally, the scale effect of the printing process is more visible. However, on the right, the same printed piece is exposed vertically, so its surface quality will be higher.
You need to think about which surface should have the best finish and choose the orientation of the print accordingly. .
3.
Weak points.
In any printed pattern there will be areas of weakness due to the orientation of the print. These areas can cause breaks in the thin outer elements of the pattern. Therefore, it is important to take into design consideration the parts of the pattern that are parallel to the base and require supports to support them.
4.
Model accuracy.
The dimensional accuracy is not related to the details of the pattern but to the deviation from the nominal size. The overall material tolerance is 0,1% with a minimum of ± 200 µ. This can be influenced by the material we use or the printing speed. In this case, it is important to know what tolerance we need in order not to invest more or less time and cost than necessary in the printing process.
5.
Supports.
Supports are structures that are printed alongside the model, but are not part of the original design and are used to support protruding parts of the model that extend beyond 45º. Since they are not part of the actual model, we remove them once the printing is completed.
In general, projections of up to 45 degrees can be printed without loss of quality. This is because each new layer has enough support to remain intact and make printing possible.
However, anything over 45 degrees approaches the horizontal and becomes difficult to print. These overhangs are prone to bending or falling off, so we add these supports to the pieces ourselves and then remove them. Using these supports makes the surface finish rougher.
6.
Base.
The first layer is the one that will provide the necessary stability for the model, so it should be as flat as possible in order to have a larger grip surface. With this in mind, bear in mind that the bottom surface will be harder than the rest of the model.
7.
The space between moving parts.
When designing a product with moving parts, the space between surfaces is crucial. The space will determine the flexibility or ability to match the design. It is recommended to leave a minimum space of 0.3 mm between surfaces.
8.
Assemble.
When designing models to be assembled, it is important to leave sufficient distance between the parts to be joined. A perfect fit with CAD software does not imply a perfect fit in print, as the software actually ignores friction. It will therefore always be advisable to leave at least 0.3 mm between the different parts.
9.
Engraved and embossed details.
It is normally preferable that the details are embossed. For engraved details, letters with a minimum line thickness of 1 mm and a depth of 0,3 mm are recommended. For embossed details, a minimum line thickness of 2,5 mm and a minimum depth of 0,5 mm is recommended.
10.
Fillet.
Often, our designs are made up of several pieces that will be joined together after being printed. Keep in mind that there are differences between what is designed and what is printed, because getting 0 tolerance in the physical world is impossible. There are certain tolerance values that are acceptable and do not affect the function of the designed part.
For making threads and screws, a suitable tolerance would be 0.25 mm. In addition, the thread pitch spacing should be at least 3 mm to ensure a good end result.
