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Start with a Good .STL or .OBJ

Exporting Your Model as .STL or .OBJ

The PreForm print preparation software can import models saved in the .STL or .OBJ file formats, the most common file types for 3D printing. Most 3D CAD packages can export directly to .STL or have add-on tools to help. PreForm also accepts the .OBJ format exported by most animation software. Larger .STL or .OBJ files require more time for PreForm to import.

Consider reducing the file size when exporting from your 3D CAD package. There is not a definitive upper limit on the size of a file you can open in PreForm, as it is dependent on your hardware. PreForm will handle models with about 3 million vertices on most hardware. Higher-end hardware can open models with more data. Most CAD programs the quantity of vertices in a model when you export a file .

Saving the .form File Type

Saving a file from PreForm creates a new file format, a .form file, which is the format uploaded to Formlabs machines for printing. After importing an .STL or .OBJ, always save changes to the .form file. Saving in the .form file format allows for repeating prints without recreating orientation and supports, as well as fine tuning adjustments when iterating on prints' setup.

A .form file is a container has the model data (.STL information), as well as the print settings specific to the Formlabs print process. The file format enables transfer of this data from one user or machine to another without having to recompile all those settings over again.

Be prepared to share the .form file for your print whenever communicating with Formlabs about your print quality. Accessing the specific data that was sent to the printer is essential to understanding the print configuration.

Form Tip

Meshlab is a free software tool that can convert several 3D CAD file formats to .STL or .OBJ.

Repairing Files

All 3D CAD is great for creating printable models, but some 3D CAD tools export better than others. PreForm will attempt to repair any mesh defects in your models to make them ready for printing. PreForm utilizes NetFabb's automatic model repair functions to repair your 3D model upon import, making it easy for you to print without worrying about model integrity.

Units (and Scaling) in PreForm

PreForm always assumes that the values in an .STL or .OBJ file are in millimeters. 

If you intend your model's units to be inches, select the model and select the “in” option under Model Units in the Edit menu.  This will make the model appear 25.4 times bigger. This is because a “1.0” in the .STL file now means 1.0 inch instead of 1.0 mm. 

On the other hand, if you saved the model in units of meters, a cube with 3 cm (0.03 m) edges will be read by PreForm as having 0.03 mm side lengths. 30 microns is ten times smaller than the printers' minimum feature size, and PreForm will automatically scale such a model by a factor of ten or more, so that it's large enough to print.

If an imported model is bigger than the build volume, PreForm will scale down the model to fit in the build volume when it is opened. If you open the scale tool, you'll see how much the model was scaled. 

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