Common file errors:
Holes
Any holes in a mesh makes it non-manifold and must be closed. If there is supposed to be a hole, the shell around it must be solidified – that way there will be a volume that the printer can read.
Non-matching edges:
With an unequal number of vertices on two connecting edges/faces, it can be interpreted as a hole in the mesh. The "hole" will, however, not be visible if the edges are along each other, but most software will be able to identify them as non-manifold edges.
Crossed volume
Volumes cannot intersect, so when two or more volumes cross into each other they must be combined with a 'boolean operation'. This way the two volumes will be combined into one.
Wrong normals
Normals help the computer understand what is in and out, and what the volume of the model is. All normals must be outward facing.
Double corners
The volume of a 3D mesh must be clearly defined, so a vertice, edge or face can only be a part of one shell. A similar issue can occur if one has by accident made a face inside a mesh or between existing geometry. These errors can also be found as being non-manifold edges.
Color prints:
For multi-color prints it is important that the 3D model is UV unwrapped correctly over the texture file and that the files are linked correctly.
UV unwrapping is the practice of "cutting open and folding" a 3D model over a 2D image. Image an orange being peeled and flattened.
For a 3D printer to read the file as a 3D color model, the files must be linked correctly. Usually this connecting them in 3D software and putting them in the same zip folder.
It is also important that the texture file is of adequate resolution.
Design tips:
Escape holes
For any cavities there must be sufficient escape holes for support material to escape. The size of the hole depends on the size and shape of the cavity in the 3D print.
Clearance
To avoid parts fusing when 3D printing, the clearance must be above the minimum clearance*. This is important for parts that must be able to move independently, interlocking parts etc.
Shrinkage
For precision 3D printing it should be taken into account that most materials shrink after printing. So, if a 3D printed part has to fit exactly with something, it is a good idea to leave some space for shrinkage. It is hard to estimate exactly how much a 3D print shrinks after printing.
Strength
To avoid breaking, minimum wall and wire thickness* should be obeyed. For parts under more stress extra thickness may be necessary. If for instance a wire is long and carries more weight than its own, the minimum wire thickness will not be enough to prevent it from warping or breaking. On the contrary, for 3D prints that should be flexible the walls and wires should not be too thick.
Details
To ensure that details such as engravings or embossings show, minimum detail specifications* should be followed. To make sure that, for instance, an engraving shows up nicely, one can either deepen or widen the engravings – or both.
Resolution
To avoid visible triangles, the mesh resolution must be high enough according to the print size. A larger 3D print naturally needs a higher resolution.
On the other hand, there is no reason to make the resolution too high as the file will be overly large and hard to handle, so many files can easily be decimated without lowering the quality.
*check material specifications at your print service or at the manufacturer of your material.
Ways to save:
Hollowing
The most efficient way to save material and money on a 3D print is, if possible, to hollow the model out. This is best on large models, and can easily save over 90 % material.
Intelligent fill
A wire mesh is more than strong enough to do the job of solid fillings with a fraction of the material use. So my replacing solid walls or connections one can save over 75 % material.
Size
Scaling down a 3D model can give surprisingly large material savings. A 20 % smaller cube uses only half as much material.
Material
Materials can be expensive, so if the needs of a project can be fulfilled with a cheaper material that is an easy way to save without the need of changing the 3D model.
3D printing:
Own 3D printer
If you need many 3D prints and want them very fast, it can be a good idea to purchase one.
3D print service
To avoid large investments of money and time and to get the best quality, highest reliability and largest selection of materials, a professional 3D print service is the way to go.
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