Good looking parts start with great design. This is no secret among the engineering community. Thanks to software like SOLIDWORKS and the many advancements in 3D printing, building complex objects in the digital world and translating them into the real world is more achievable than ever. In this article, I demonstrate how to optimize your design and orient your 3D part file for successful and great looking prints using an FDM-style 3D printer such as the MakerBot Replicator+.
Step 1: Recognize that not every design is great for 3D printing.
As for most things that seem too good to be true, 3D printing has its limitations. The key to optimizing parts for 3D printing is remembering the capabilities of your machine.
For example, you can’t print on thin air. Gravity is a constant force that must be considered when designing and printing in 3D. As with most additive manufacturing processes, FDM (Fused Deposition Modeling) begins building parts layer-by-layer vertically on the Z axis. Complex parts commonly have overhangs in the design that branch out without any elements in the design to brace them. In 3D printing, overhangs without vertical stabilization will undoubtedly sag or worse, make your part fail.
Step 2: Find a design solution to overcome limitations.
To combat restrictions such as gravity, 3D printing software can automatically process your part file to find any of these overhanging areas and automatically generate support structures that are meant to be removed later. Understanding how support is generated and why will help you create nicer quality parts for 3D printing. Here is a list of solutions that can help optimize your design.
Type of Support Material
On 3D printers with two extrusion heads, there is a separate support material that is purposefully weaker or solvable in a chemical bath for easy removal. On the MakerBot Replicator+ and other printers with a single printing head, you are limited to “breakaway support” which is the same extruded thermoplastic as the model material. But instead, breakaway support is attached at finely spaced points to your model. These support structures can leave nasty marks or scars when removed and often need to be post processed, so it is best to limit their use or remove them from your design completely if possible.
There are some design choices and exceptions that can affect the need for support. If an element in your design is very small such as a screw hole or other small feature, FDM printers can bridge horizontal gaps of short distances in midair safely without sagging. Bridging will remain accurate to your parts geometry and vary with printing speed, temperature and the material used. Removing support usage from these small areas can speed up printing and post-processing time.
Another important point to keep in mind when designing your part is self-supporting angles. A self-supporting angle is an angle up to 45 degrees, which will eliminate the need for additional support because each new layer is supported by half of the previous layer.
Below is an example of how a steady slope can allow for complex geometries that are reinforced enough to prevent any sagging or need for support material. This can affect your print not only in design but also when orienting your part to prepare for printing.
|Above: Illustration of individual layers of a feature at a 45-degree angle using self-supporting angles. Each new layer is supported by 50% of the previous layer.|
Altering your orientation can allow for more self-supporting angles and, therefore, less support usage and less scarring from support removal on your final form. In this example, choosing the correct orientation is important for both printing speed and strength as well. 3D printed parts can be weaker along the “grain” of the layers, so it is important to know the weak points in your part and orient your part relative to the build tray keeping this in mind.
|Left: Sample part with an overhanging feature, Center: Computer generated support structures bracing the overhanging features, Right: When the part is rotated 45 degrees, self-supporting angles cause the software (MakerBot Print) to generate less support|
Using Less Support Material
Using less support for bracing not only can make your part look better by preventing surface blemishes, but it also saves money and time. When designing your part, making choices to reduce model material is a great way to streamline your part design and keep costs down.
SOLIDWORKS features such as Fillets and Chamfers can enhance your design visually and shave off excess material from the edges of your part. More advanced features such as Optimization inside of SOLIDWORKS Simulation Suite can analyze and refine your design even further to obtain the optimum strength and mass for your part with many stress factors and variables to adjust within the software. Once you have your part file ready for printing, there are more options available in your slicing program that can also affect strength and material. Some of these include adjusting the parts infill density, layer height and support options.
|Left: Original part, Right: Sample part that has been optimized to reduce materials, weight and printing time|
These are a just few things to consider when designing parts for 3D printing. Good planning in the design stage of development can produce better looking and more ergonomic parts, all while limiting your material costs.
Aside from optimizing your design, also be sure you are using materials best suited for your specific industry and application. Download our 3D Printing Material Guide to learn about different material properties.
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