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Ordering 3D Printed parts: Which Filetype to use?


Since the introduction of 3D CAD (Computer-Aided Design), numerous software companies have developed their own file formats, each with varying features and compatibility. This potential incompatibility poses challenges when sending 3D files to Service Bureaus. To address this issue, 'Neutral' formats were introduced. These formats are not tied to any individual software, ensuring a higher level of compatibility across different programs.

This article explains the difference between the most commonly used Neutral 3D CAD formats for ordering 3D Printed Parts: STL, STEP, and 3MF.

A generic 3D CAD image of an MJF Build.

STL Format:

Ordering 3D Printed parts with STL Format is extremely common. It is the oldest format on this list, dating back to 1987, and its fundamentals are straightforward. Conceptually, this format divides your part into a series of triangles. While simple, this method can result in very large file sizes, especially for complex parts.

Controlling STL quality / tolerance...

When exporting your part to STL format, most CAD systems offer options to control the quality of the mesh. If the quality is too low, curved edges may appear as a series of triangles, and fine details may deform or not show at all. Conversely, overly fine settings can lead to excessively large file sizes, making uploading to our portal or attaching to an email challenging. As a general rule, for a single part, anything over 70MB is usually unnecessary.

A comparison showing poor quality STL files vs good ones.  On the poor one the shape of the curved surfaces on the part become jaggard as the triangle count is too low.

Remember that STL Files don't contain units:

Sending an STL file to us means we won't know if you modelled it in millimetres, inches, or any other unit. As standard, we work in millimetres (mm), but our online portal can also be adjusted to meters (m) or inches. When ordering via email, unless specified otherwise, we will assume the units are in millimetres.

STEP Format:

With STEP files, you can order 3D Printed parts without grappling with mesh quality settings since they are not based on triangles. Additionally, there's greater flexibility for advanced design modifications compared to the STL format. In most cases, STEP files are the preferable option.

If your design is already in a triangle-based format, translating it back into STEP can be very challenging, so it's advisable to continue using triangle-based formats like STL.

Comparison of STEP & STL file formats on the same part, a pencil sharpener.  It shows how the STL is made up of lots of triangles while the STEP file is curved surfaces.

3MF Format:

3MF is the newest addition to the group, specifically developed for 3D Printing. It can include information about materials and finishes, which is absent from the .STL format.

Moreover, it offers a more file-size efficient way of transferring CAD Data.

Although our online portal doesn't directly support 3MF at the moment, we still accept these files via email or our contact form.

Other Formats:

We also accept a range of other file formats, both neutral and native, including: .OBJ, .IGES/.IGS, .SLDPRT (SOLIDWORKS), .3DM (Rhino), .F3D (Fusion), and .SKP (Sketchup). Given our work with various industries, each with its unique requirements, we maintain copies of a wide array of CAD packages. This ensures we have numerous options for converting, editing, or simply 3D printing from different file formats.

CAD Programs we have:

  • Materialise Magics


  • Rhinoceros 3D (Versions 5 & 7)

  • nTopology

  • Autodesk Fusion

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