5 Mistakes to Avoid When Designing a 3D Model for 3D Printing.
1. Ignoring Material Guidelines.
Each and every printing material is different. Materials can be brittle or strong, flexible or solid, smooth or rough, heavy or light, and so on. This also means that an object should ideally be designed for a specific material. For example, if you know that you want to print your 3D model in Steel, there will be specific material-related design recommendations that you need to take into account such as supporting overhanging parts, strengthening elements that are sticking out, rounding off corners, etc.
The choice of your printing material simply pre-determines some of the basic design guidelines that you need to stick to.
The best example of this is interlocking parts; in materials like ABS, Polyamide, Alumide, or Rubber-like you can print interlocking parts, while in others like Gold, Silver, Bronze, or Resin this is not possible. The reason behind this is not the material itself, but the technology that is used for printing each of these materials.
For ABS you need to use Fused Deposition Modeling (filament-based) with an extra nozzle and material for support, for Polyamide, Alumide, and Polypropylene you need to use Laser Sintering (powder-based), for precious metals we use lost wax casting (based on a 3D print in wax and a mold), and for the Resins, we use Stereolithography (liquid polymer-based).
This might sound confusing but the important thing to keep in mind is the following: we cannot assume that Stainless Steel and Silver will have similar requirements simply because they are both metals. They are printed using different technologies and thus some design features will differ. However, materials that use the same technology such as Gold, Silver, Bronze, and Brass (lost wax casting) are more likely to share similar design requirements.
3. Ignoring Wall Thickness
Problems linked to wall thickness are by far the most common reasons why some 3D models are not printable. In some cases, wall thickness is too thin. Walls that are too thin make small parts on the model unable to be printed or very fragile and could break off easily. In other cases, walls that are too thick generate too much internal stress and could cause the item to crack or even break.
4. Ignoring File Resolution
For 3D printing, the most common file format is STL (which stands for standard triangle language), which means that your design will be translated into triangles in a 3D space. Most 3D modeling software has the option to export your designs to an STL file and set the desired resolution.
Low-resolution STL file: It’s important to be aware that a poor-quality export will never provide you with a good print. Low-resolution means that the triangles in your STL file are big and the surface of your print will not be smooth. It will lead to a somewhat “pixelated” print.
Very high-resolution STL file: A file with a resolution that is too high will make your file too big and sometimes impossible to handle. It might also contain an extreme level of detail that the 3D printers simply cannot print.
5. Ignoring Software Guidelines
There are many different 3D modeling software packages. Some were designed for creating 3D prints, others are mostly used by 3D artists and their designs will require additional editing before they can offer a printable 3D model. For example, applying a wall thickness is automatic in some programs, while you must manually set it in others.
Even if you use beginner-friendly software that was developed for the sole purpose of 3D Printing (e.g. Tinkercad), you might still have a difficult time creating a hollow model. In this case, free software Meshmixer can help.
If you use software like Blender (used for 3D graphics and animations), SketchUp (popular with architects and scale modelers), or ZBrush (sculpting software for 3D artists), some further file preparation will need to be done. Depending on which software you are using, shells may need to
be joined together, models may need to be made watertight, wall thicknesses may need to be applied, and printing sizes may need to be set. Once again, each and every software is different.