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There are a lot of CAD (computer-aided design) file types out there, each with their own names, formats, and parameters. From STEP files, to STL files, to IGES, and more, it can be difficult to differentiate between them all. This post will help you understand the difference between these file types, and which file is best for uploading to a 3D printer or 3D printing service.
Before we review the steps for CAD file preparation for 3D printing, here’s a brief overview of different CAD model types.
One very basic way to distinguish between CAD models types is by breaking it into these two groups:
A parametric model is one which consists of solid blocks or vectors that have both magnitude and direction. A mesh model, on the other hand, is a collection of small triangles that make up a surface.
If you compare these two types of models to a 2D image file, a parametric model is like a vector file (.AI, .SVG, .DXF) while a mesh model is most similar to a pixel image (.PNG, .JPEG).
Just as a pixel image (.PNG) approximates a vector file (.AI), when converting a parametric model to a mesh model, a mesh file (.STL) approximates a parametric file (.STEP).
Pro Tip: If you’re looking for an in depth read about mesh modeling vs solid modeling, check out this article.
Now let’s dive into how you can prepare and export your CAD models for 3D printing and which file types we recommend.
There are 3 main file types used in 3D printing:
This file type was created by the US Air Force and was used for exchanging CAD geometry. It was later adopted by the American National Standards Institute (ANSI).
Main thing to know about this file type is it’s an older, unsupported specification so it will never be updated or changed. Hence, why this is the third best choice for 3D printing files.
There are two types of STL files:
STLs were originally developed by 3D Systems specifically for additive manufacturing and are widely known as the industry standard. However, STL files have several shortcomings. For example, there’s no associated units and holes or gaps (watertightness) can cause issues when producing parts.
There are 2 main types of STEP files:
In our opinion, STEP files are the best file format for transferring CAD data. STEP files carry all of the parametric data required so manufacturers can easily read the size and geometry of the part you need.
Pro Tip: STEP AP214 will save the colors and layers in your CAD program when exporting as an STL. When saving for multimaterial prints, we prefer this standard since it helps to distinguish the different solid bodies.
It’s easy to run into problems when exporting an STL file. Since a lot of people do use STLs we’re going to point out a few important considerations and then walk through specific exportation steps for the most common CAD programs.
The most important consideration to take into account here is the resolution of your model. If you try to export an STL with a low resolution, your model will look faceted and if you export an STL with too high of a resolution, your model will become very large and difficult to share.
There are two main settings to consider with every CAD program:
This is the maximum distance between the surface of the original design and the surface of the STL triangle created.
This is the allowable deviation between adjacent triangles. You should think about approximating a curved surface with lots of flat triangles; the more shallow the angle, the closer the approximation is to the curved surface.
If you’re ready to start uploading your design files for 3D printing you can visit Fictiv for an online quote in minutes.