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How to achieve the best quality 3D prints from your STL files

Updated: Jan 12, 2022

When 3D printing an application, new design or ingenious part, the excitement often comes in getting the CAD complete and ready to use as quickly as possible on your 3D printer.

However, there is no use in having a great idea or application if your STL files are not at the quality to match! It can be disappointing when a brilliant idea doesn't translate into the fine 3D printed part you expected. The key is to spend time creating the best quality design and STL file possible.

Here are some easy steps you can take to ensure you get the best quality 3D prints by exporting the best quality STL files for Additive Manufacturing.

Let’s get back to basics: what is an STL file?

An STL file is a file that stores information about a 3D model, describing the surface geometry of a three-dimensional object. The geometry of a 3D design is encoded using ‘tessellation’. Tessellation is a process of using geometric shapes, almost like triangular tiles, to create a shape of the 3D object with no overlaps or gaps.

Most widely used computer aided design (CAD) programmes are able to export design files in a .stl format. These STL files can then be put through a 3D slicer software and be 3D printed. 3D printing slicer softwares convert digital 3D models into printing instructions for your 3D printer to create an object.

A sample part design in Fusion 360 CAD software

So, what steps can you take to make sure that your STL files are able to produce the best quality 3D prints?

When using CAD, creating a design that you are happy with technically and functionally, is only one element of the process. It may look great in the CAD programme, but how it converts in slicing software, and ultimately when printed, all depends on your STL export settings.

Below, we have created some examples of how different export settings can affect the quality of your part. For our designs, the CAD programme used is Fusion 360.

Best Practice STL Export

Here is how your STL export settings SHOULD look, in order to achieve the best quality print.

A 3D design with good STL export settings in CAD

Settings to export a good quality .stl file from CAD

You can see from our example that the ‘Number of Triangles’ is at ‘22092’, and the ‘Refinement’ is set at ‘High’. Using this high amount of triangles is visible in the part preview, resulting in a part output with a high amount of smoothness and accuracy.

The ‘Surface Deviation’ and ‘Normal Deviation’ are both set at low values in the STL export settings. These restrictive parameters mean that the part will require a higher-resolution mesh, resulting in an STL with higher detail.

These settings shown in our example are good guidance to exporting a high-quality STL.

Mediocre and Poor STL Exports

When adjusting the ‘Refinement’ to ‘Medium’ or ‘Low’, the number of triangles decreases, and the difference in quality can clearly be seen in the part preview. This results in a higher ‘Surface Deviation’ and ‘Normal Deviation’, as less triangles are being used to cover the same part area.

A 3D design with medium STL export settings in CAD

A 3D design with low STL export settings in CAD

And if you were to set the STL refinement as ‘Very Low’, you can see when issues of part quality can really start to arise!

A close-up of a 3D design with very low STL export settings in CAD

Proof is in the Printing

When a part is 3D printed, you can see the difference in detail and quality, correlating to the settings through which the design file was exported to an STL.

On the low STL refinement printed part, you can see faceting on the outer surface. When a file is exported from CAD software at a low resolution the polygons that the outer surfaces are converted too are large. This leads to flat planes and a faceted model; this is particularly noticeable on curved faces. Increasing the export resolution will make the polygons smaller, increasing the smoothness of the part, but bear in mind that this will also increase the file size.

A part 3D printed from a good quality STL file vs a part 3D printed form a low quality STL file. Faceting can clearly be seen in the low quality part.

So there you have it, all the steps (and proof!) you need to make sure your STL files are exported to the best quality for printing.

Double checking your export settings doesn't take long, but can make a huge difference in the quality of the final 3D printed part.

If you'd like to discuss your applications with our CREAT3D Additive Experts, give us a call on 0800 689 1011 or email

How to achieve the best quality 3D prints from your STL files_CREAT3D
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