Design guide

Surface quality and print orientation

The way in which the model is printed determines several of its characteristics, one of them its surface quality. This is because the model is printed layer by layer, so the orientation of the part at the time of printing 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, printed horizontally, the staircase effect of the printing process is more noticeable. However, the same printed part is shown vertically on the right, so its surface quality will be higher.

You need to think about which surface needs to have the best finish and choose the print orientation accordingly.

Weak points

In every printed model there will be slightly weaker areas due to the orientation of the print. These areas can cause breakage in the thin external elements of the design. Therefore, it is important to avoid parts in the model that are parallel to the base and that require supports to sustain them.

Model Accuracy

Dimensional accuracy is not related to model detail but to deviation from nominal size. General material tolerance is 0.1% with a minimum of ± 200 µ. This aspect 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 money than required in the printing process.

Supports

The supports are structures that are printed next to the model but that are not part of the original design and serve to support the parts that protrude from the model that exceed 45º. As they are not part of the actual model, we remove them once the print is complete.

Overhangs of up to 45 degrees can generally be printed without losing quality. This is because each new layer has enough support to remain intact and make printing possible.

However, anything past 45 degrees gets close to horizontal and becomes difficult to print. These cantilevers are prone to bowing or sagging, so we add these supports to the parts ourselves, then remove them. The use of these supports causes the surface finish to be rougher.

Base

The first layer is the one that will give the necessary stability to the model, so it should be as flat as possible so that it has more grip surface. Considering this, it must be taken into account that the lower surface will be harder than the rest of the model.

Mobile parts

When designing a product with moving parts, the space between the surfaces is crucial. The spacing will determine the flexibility or sag of the design. It is recommended to leave a minimum space of 0.3mm between the surfaces.

Assembly

When designing a product with moving parts, the space between the surfaces is crucial. The spacing will determine the flexibility or sag of the design. It is recommended to leave a minimum space of 0.3mm between the surfaces.

Engraved and embossed texts

It is normally preferable that the details be engraved rather than embossed. For engraved details, letters with a minimum line thickness of 1mm and a depth of 0.3mm are recommended. For relief details a line thickness of at least 2.5mm and a depth of at least 0.5mm is recommended.

Threads

Many times our designs are made up of several pieces that will be put together once printed. Keep in mind that there are differences between what is designed and what is printed, since obtaining a 0 tolerance in the physical world is impossible. There are certain tolerance values that are acceptable and do not affect the performance of the designed part.

For the realization of threads and screws, an adequate tolerance would be 0.25 mm. In addition, the distance of the thread pitch must be at least 3 mm to ensure a good final result.