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Converting STEP to STL: Preparing CAD Files for 3D Printing

Converting STEP to STL: Preparing CAD Files for 3D Printing

CAD programs are powerhouses for designing 3D models. However, not all programs allow for the direct export of print-ready files. This article covers the essentials of preparing your STEP files for printing.

Computer-aided design (CAD) is a widely used technology for translating complex designs to manufacture-ready instructions for a machine. CAD programs generate STEP (standard for the exchange of product data) files, which are an ISO standard exchange program that ensures that CAD designs can be opened and edited on a variety of programs by international users. These models contain color and form information.

In contrast, STL files describe the geometric characteristics of three-dimensional objects only, lacking descriptive information like color or material. Generated using triangular mesh, these files are primed for translation into G-code for printing.  

Unlike converting DOC to PDF files, the ease with which STEP files can be converted often depends on the maker’s skills and the complexity of the model. Below, we cover the best ways to convert your files and prepare them for 3D printing.

Use your CAD program

If you designed your own model in a CAD program, it should be relatively easy to generate a print-ready file using the “Save As” or “Export” commands. Note that some free or trial programs may have limitations on the number or types of exports you perform.

In Fusion 360, which we’ve covered before, individual bodies and components can be saved as STL files by right-clicking them and selecting “Save as STL.” Here, it is important to ensure that all the parts of your model connect where they should to avoid broken or incorrectly split prints.

Because these programs are designed with various 3D printing manufacturing styles in mind, using a CAD program is the best way to convert your STEP file to an STL file. However, if you do not have access to a program—perhaps you only downloaded a model from a repository or your computer cannot run any free programs—there are some other options available.

Contact a maker or designer

Websites like Fiverr can quickly connect you to someone with the skills and tools to convert your file, often for a very low fee. While it may feel unnecessary to pay someone to convert a file for you, this is a good option for those who do not have access to a CAD program that can ensure security and file integrity or those who are working with STEP files that may require modification before conversion.

Use a converter program

 There are dedicated online tools designed for converting STEP files into STL files, such as makexyz. These are typically simple, near-instant conversion that require only a few clicks. However, as with any automated conversion not run on a dedicated program, some online tools may pose security risks or incorrectly modify the file. While these can be great accessible tools, we still recommend using a free CAD program that can be run off of your computer for improved security.

The cover photo illustrates the triangular mesh form used in STL files and was obtained from Formlabs.

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