Wall thickness

The thickness of the wall is the distance between a surface of the model and the adjacent opposite surface. To obtain a good result and a resistant product, it is recommended that this thickness is not less than 1 mm.

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 that the orientation of the piece at the time of printing will determine its surface quality. The same printed piece with a different orientation will have a different finish.

An example of this can be seen in the previous image. On the left, printed horizontally, the staircase effect of the printing process is more noticeable. However, on the right the same printed piece is shown vertically, so that its surface quality will be higher.

It is necessary to think about which surface needs to have the best finish and choose the printing orientation accordingly .

Fragile points

In any printed model there will be somewhat weaker areas due to the orientation of the print. These areas can cause breaks 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 support them.

Model Accuracy

The dimensional accuracy is not related to the detail of the model but to the deviation from the nominal size. The general tolerance of the material is 0.1% with a minimum of ± 200 µ. This aspect may be influenced by the material we use or the printing speed. In this case it is important to know what tolerance we need to not invest more or less time and money than is 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 protruding parts of the model that exceed 45º. As they are not part of the real model, we remove them once printing is complete.

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

However, anything that goes beyond 45 degrees approaches the horizontal and becomes difficult to print. These overhangs are prone to bend or fall, so we ourselves add these supports in the pieces, and then remove them. The use of these supports causes the surface finish to be more rough.

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 should be taken into account that the lower surface will be harder than the rest of the model.

Space between moving parts

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

Assembly

When designing models that need to be assembled it is important to leave enough distance between the parts that will be joined. A perfect fit with the CAD software does not imply a perfect fit in the print because the software actually ignores the friction. Therefore, it will always be advisable to leave at least 0.3 mm between the different parts.

Engraved and embossed details

Normally it is preferable that the details are recorded to be embossed. For engraved details, letters with a minimum line thickness of 1 mm and a depth of 0.3 mm are recommended. For relief details, a line thickness of at least 2.5 mm and a depth of at least 0.5 mm is recommended.

Threads

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

For the realization of threads and screws, a suitable 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.