How to design and create solid 3D printed objects

FDM 3D printers are perfect for creating affordable prototypes and undertaking DIY projects at home. Despite this, many people face the same problem when trying to make functional parts with a 3D printer: the strength of the finished product. But how do you make your 3D prints stronger? Let’s take a look at some of the key steps you can follow at each stage of the printing process.

Choosing the Right Materials for Strong 3D Prints

Materials play an important role in the strength of the 3D prints you create, and there are plenty of filament options to choose from. It is important to evaluate the filaments you choose based on the needs of the objects you are printing. For example, PLA is fine for ornamental models that will sit on a shelf, but you may need a material like nylon to print functional tools. You can find a range of filament options below along with their best use cases.

  • PLA: PLA, or polylactic acid, is the most common material used for FDM 3D printing. This material is stiff and hard, but it is also relatively brittle compared to other 3D printable materials. PLA is a good choice for those new to 3D printing because it’s easy to print and will almost always deliver good results.
  • ABS: ABS, or acrylonitrile butadiene styrene, is much stronger than PLA, but it’s also harder to print. The strength of ABS makes it ideal for functional parts, but it is stiff and this needs to be considered when choosing your filament.
  • PETG: PETG, or polyethylene terephthalate, is a happy medium between ABS and PLA. It is stronger than PLA and more flexible than ABS, while offering excellent chemical resistance. This makes PETG ideal for outdoor use and other harsh environments.
  • Nylon: Nylon is one of the strongest, most flexible and most durable FDM materials on the market. Nylon 3D printer filament can be used to make functional parts and tools, as well as decorative items.
  • Carbon-impregnated filaments: The inclusion of carbon fibers in the filaments has become very popular. This rarely improves the strength of finished prints, but it can improve layer adhesion.

Choosing the right 3D printer filament material for a given project is difficult. You should explore all of the available options when selecting your filament, especially when working on objects that need to last.

Design solid 3D models for 3D printing

Just like the materials you choose for your 3D prints, the design of each print also has a huge impact on the durability of your 3D prints. Designing stronger 3D printable models takes some learning. While you may not be able to start creating the strongest impressions right away, below are some of the key considerations you need to take into account. Your 3D model designs will improve over time and you will learn more about creating solid forms.

Error-free 3D printable STL files

Whether you use Blender, Fusion 360, or any other 3D design tool to create 3D printable models, errors are bound to occur from time to time. Non-manifold models are a good example of this, where there are gaps on the outside of the model that can prevent it from slicing properly.

Solving this kind of problem is easier than ever. Almost every slicer on the market, including Cura, can scan your models for errors as you load them up to slice, often offering repairs along the way. Of course, however, it’s always best to learn and improve the quality of your 3D modeling to avoid mistakes in the first place.

Stress distribution and 3D printing

Predicting exactly where mechanical stress will affect a 3D printed object the most is a challenge. Engineers perform complex mathematical calculations to figure this out when working on large projects, but you can use your intuition to solve this problem when working on your own designs. You just have to think about whether the shapes you create are going to be solid or not.

The image above is a good example. Without any form of bracing, the piece leaning to the left would be very weak and prone to breaking if a force was applied to either end. The angled piece on the right has a brace that will work to fix this. You can consult the work of professional engineers to get an idea of ​​the strongest shapes and apply them to your designs.

Slice solid 3D models for 3D printing

Another factor that will impact the strength of your 3D prints is the settings you choose in your slicer software. Slicer software can be daunting when you first get started, but we’ve broken down the most important settings to keep in mind when working to improve the resilience of your 3D prints.

3D Printing Density and Fill Patterns

It would be time consuming and expensive for 3D printers to create solid objects, and most slicer software defaults to infilling inside objects to save time and filament. An infill density between 20% and 30% is generally as strong as a solid object, but diving below this threshold may result in weaker prints.

Density, however, is not the only factor to consider. Most slicers also offer the option to choose different fill patterns for your 3D prints. Hex fills are very common, but 3D or random fill options are often stronger. You should experiment with your slicer’s fill options to get the best results.

Suitable inner and outer wall thickness

Although the inside of your 3D print is not solid, the exterior and interior walls it has are. Adding extra walls to make them thicker will improve the strength of your 3D prints to a limit, so it’s worth experimenting with this option for best results. Most slicers will warn you if your wall thickness is too high.

Choosing the Right 3D Printing Orientation

As you probably know, FDM 3D printers print in layers. The layers adhere to each other, but the bonds between each layer are usually the weakest part of a normal 3D printed object. You can think of this as being similar to woodworking: a skilled carpenter will always work in the direction of the grain to make sure the pieces are strong.

You can change the orientation of your 3D prints in your slicer to improve their strength in the same way. By ensuring that the constraint will follow the direction of the layers, rather than going against them, you will reduce the risk of splitting and other issues with your prints.

Finishing 3D prints to add strength

Finally, as a final area to consider, it’s time to think about finishing methods for 3D printing that can make your objects stronger. There are many ways to finish 3D printed objects, but only one will add strength to your models: epoxy resin coatings.

You can apply epoxy resin to your 3D printed objects once they are finished. This will add a hard layer to the outside of your prints, while hiding any layer lines that formed while printing. Of course, however, this should be used alongside the other tips in this article, not as a replacement.

Make 3D prints stronger

Strength is an important aspect when crafting just about anything. FDM 3D printers have the ability to make incredibly strong objects, but they rely on the user to reach their full potential. In short, the techniques we’ve covered here are a great start for anyone looking to improve the strength of their 3D prints, but you also need to apply your own creativity to this problem to get the best results.

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